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This is to certify that the

thesis entitled

Chemical Additions for Phosphorus Reduction In
Liquid Dairy Manure

presented by

Dana Matthew Kirk

has been accepted towards fulfillment
of the requirements for

M.S. flageein Biosystems Engineering

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CHEMICAL ADDITIONS FOR PHOSPHORUS REDUCTION IN LIQUID
DAIRY MANURE

By

Dana Matthew Kirk

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Agricultural Engineering

2002

ABSTRACT

CHEMICAL ADDITIONS FOR PHOSPHORUS REDUCTION IN LIQUID
DAIRY MANURE

By

Dana Matthew Kirk

Current trends in the dairy industry are for larger production facilities on smaller
parcels of land. The trend of increasing herd size and decreasing land base has driven
dairy producers to look for alternative treatment and utilization options for manure
nutrients. Separation of manure nutrients into a liquid stream high in nitrogen and a
solids stream rich with phosphorus allows for more flexibility in storage, transport, and
utilization or export of manure nutrients. Treating liquid dairy manure (with an average
of 2.85% total solids) with chemical additions in the laboratory and field experiments
proved to significantly reduce soluble (SP) and total (TP) phosphorus in the liquid
fraction. Chemical coagulants investigated with liquid dairy manure included lime, alum,
and ferric chloride. Laboratory experiments using lime, alum, and ferric chloride reduced
TP in the liquid fraction by up to 75%, 100%, and 82%, respectively, after 24 hours of
settling. Settling for 24 hours with mixing as the only form of treatment decreased TP in
the liquid dairy manure by 60%. Field experiments showed that 48 hours of natural
settling reduced TP in the liquid by 55%, mixing increased the TP reduction to 73%.
Chemical additions of lime, alum, and ferric chloride in the field tests reduced TP by

70%, 81%, and 71%, respectively.

Dedicated to Mom, Dad, Kevin, and Lindsay

iii

ACKNOWLEDGEMENTS

For the years of guidance and mentoring, I would like to thank my Major
Professor, Dr. William G. Bickert. It has been both an honor and pleasure to work with
you and learn from you for the past seven years. Words alone cannot express my
gratitude.

In addition, I would like to thank the members of my guidance committee: Dr.
Simon Davies, Agricultural Engineering Department; Dr. Syed Hashsham, Department of
Environmental Engineering; and Mr. Andrew Wedel, McLanahan Corporation.

I also need to thank Joseph Nguyen for allowing me to use the Environmental
Teaching laboratory to conduct my research. Without his assistance and cooperation, this
research project would not have been a success. I am extremely appreciative of Velmar
and Craig Green of Green Meadows Farm, for allowing my research to be conducted at
their dairy in Elsie, MI. To my research assistants, Josh Miller and Joel Brook, thank you
both for your diligent work on this research project. The following people provided
assistance and support that was invaluable to this project: Dr. Joseph Domecq, MSU
Department of Animal Science; Natalie Rector, MSU Extension; Richard Wolthuis and
Nancy Aitcheson, MSU Agricultural Engineering Department.

Finally, I need to thank those who helped to maintain my sanity throughout my
Master’s research, my friends and family had probably the toughest job of all. Thank

you.

iv

TABLE OF CONTENTS

LIST OF TABLES ................................................................................ viii
LIST OF FIGURES ................................................................................. x
LIST OF ABBREVIATIONS ................................................................... xii
1. INTRODUCTION ............................................................................... 1
1.1 Industry Scope ............................................................................... 1
1.2 Statement of Problem ....................................................................... 1
1.3 Proposed Solution — Chemical Phosphorus Separation ................................. 3
1 .4 Objectives ..................................................................................... 4
1.5 Thesis Organization ......................................................................... 4
2. LITERATURE REVIEW ...................................................................... 6
2.1 General Comments ........................................................................... 6
2.2 Agricultural Phosphorus .................................................................... 7
2.2.1 Phosphorus Transport from Agricultural Fields ......................... 8
2.2.2 Agricultural Phosphorus and Water Quality .............................. 9
2.3 Physical Separation ......................................................................... 10
2.3.1 Settling ....................................................................... 10
2.3.2 Mechanical Separation ..................................................... 12
2.4 Phosphorus Removal and Recovery ..................................................... 14
2.4.1 Biological Phosphorus Removal .......................................... 15
2.4.2 Mechanisms of Biological Phosphorus Removal ...................... 15
2.4.2.1 Anaerobic Phase ................................................. 16
2.4.2.2 Aerobic Phase ................................................... 17
2.5 Mechanisms of Chemical Phosphorus Removal ....................................... 18
2.5.1 Coagulation and Precipitation ............................................. 19
2.5.2 Flocculation .................................................................. 21
2.5.3 pH Adjustment .............................................................. 22

2.5.4 Solids and Phosphate Removal using
Chemical Additions and Organic Polymers ..................... 23
2.5.4.1 Calcium ........................................................... 24
2.5.4.2 Aluminum ........................................................ 25
2.5.4.3 Iron ................................................................ 26
2.5.4.4 Polymers ......................................................... 27
3. EXPERIMENTAL METHODS ............................................................ 30
3.1 General Comments ............................................................................. 30
3.2 Standard Techniques and Procedures ........................................................ 30
3.2.1 Soluble Phosphorous ............................................................... 30
3.2.1.1 Materials .................................................................. 30
3.2.1.2 Methodology .............................................................. 31

3.2.2 Total Phosphorous .................................................................. 32

3.2.2.1 Materials .................................................................. 32

3.2.2.2 Methodology .............................................................. 33

3.2.3 Calibration Curve Preparation ..................................................... 34

3.2.3.1 Materials .................................................................. 34

3.2.3.2 Methodology .............................................................. 34

3.2.4 Chemical Oxygen Demand ......................................................... 35
3.2.4.1 Materials .................................................................. 35

3.2.4.2 Methodology .............................................................. 35

3.2.5 Hot Weight ......................................................................... 36
3.2.5.1 Materials .................................................................. 36

3.2.5.2 Methodology .............................................................. 37

3.2.6 Total Solids ........................................................................... 37
3.2.6.1 Materials .................................................................. 37

3.2.6.2 Methodology .............................................................. 38

3.2.7 Fixed and Volatile Solids ........................................................... 38
3.2.7.1 Materials .................................................................. 39

3.2.7.2 Methodology .............................................................. 39

3.2.8 Turbidity .............................................................................. 40

3.2.8.1 Materials .................................................................. 41

3.2.8.2 Methodology ........ ” ...................................................... 41

3.2.9 Temperature and pH Analysis ..................................................... 42

3.2.9.1 Materials .................................................................. 42

3.2.9.2 Methodology .............................................................. 42

3.2.10 Manure Sampling ................................................................... 42
3.2.10.1 Materials ................................................................. 44

3.2.10.2 Methodology ............................................................. 44

3.2.11 Jar Test Procedure .................................................................. 44
3.2.11.1 Materials ................................................................. 45

3.2.11.2 Methodology ............................................................ 45

3.2.12 Glassware Preparation ............................................................ 47
3.2.12.1 Materials ................................................................. 47

3.2.12.2 Methodology ............................................................ 48

3.3 Pilot Unit ......................................................................................... 48
3.3.1 Pilot Unit Tests ...................................................................... 48

3.3.1.1 Materials .................................................................. 49

3.3.1.2 Methodology .............................................................. 50

4. RESULTS AND DISCUSSION .............................................................. 51
4.1 General Comments ............................................................................. 51
4.2 Manure Stream Characterization ............................................................. 51
4.3 Laboratory Testing of Coagulants and Liquid Dairy Manure ............................ 55
4.3.1 Settling with No Chemical Coagulants .......................................... 56

4.3.2 Lime Additions ...................................................................... 57

4.3.3 Alum Additions ..................................................................... 60

4.3.4 Ferric Chloride Additions .......................................................... 64

vi

4.3.5 Chemical Treatment Cost Analysis ............................................... 67

4.4 Pilot Unit Results ............................................................................... 69
4.4.1 Velocity Gradient Calculations .................................................... 70

4.4.2 Pilot Unit Tests ...................................................................... 70

4.4.2.1 Pilot Unit Sampling ...................................................... 72

4.4.2.2 Phosphorus Reductions without Chemical Additions ............... 73

4.4.2.3 Phosphorus Reductions with Lime Additions ........................ 79

4.4.2.4 Phosphorus Reductions with Metal Salts (Alum and Fer). . . . ...81

5. SUMMARY AND CONCLUSIONS ........................................................ 87
5.1 Summary ........................................................................................ 87
5.2 Conclusions ..................................................................................... 87
5.2.1 Laboratory Experiments ............................................................ 87

5.2.2 Pilot Unit Experiments .............................................................. 89

LIST OF REFERENCES ........................................................................ 90
APPENDIX .......................................................................................... 94

vii

2.1:

2.2:

2.3:

2.4:

4.1:

4.2:

4.3:

4.4:

4.5:

4.6:

4.7:

4.8:

4.9:

4.10:

4.11:

4.12:

A1:

A4:

A5:

LIST OF TABLES

Types of Settling Phenomena Involved in Wastewater Treatment .................. 11
Municipal Wastewater Vs Dairy Manure ............................................... 19
Typical Velocity Gradient (G) and Detention Time Values for

Wastewater Treatment Processes ......................................................... 22
Chemicals Used in Wastewater Treatment ............................................. 23
GMF Manure Stream and Dilution Water Volumes for 3,600 Cows ................ 52
Liquid Manure Stream Characterization Summary .................................... 53
Split Sample Analysis and Average Coefficient of Variance ........................ 53
Control Jar — Phosphorus Reduction ..................................................... 56
Phosphorus Concentration Reduction Using Lime .................................... 58
Phosphorus Concentration Reduction Using Alum .................................... 61
Phosphorus Concentration Reduction Using FeC13 .................................... 64
Chemical Doses for Desired Reduction in Phosphorus Concentration ............. 67
Common Phosphate Fertilizers and Prices ............................................. 68
Comparison of Chemical Costs Vs Value of TP Recovered ......................... 68
Horizontal Plane Differences in the Pilot Unit“ ........................................ 72
Averaged Phosphorus Reduction at Sampling Port 2 in the Pilot Unit ............. 79
Manure Stream Characterization, Green Meadow Farms ............................ 94
Lab Results Using Lime as the Chemical Coagulant .................................. 95
Lab Results Using Alum as the Chemical Coagulant ................................. 96
Lab Results Using FeC13 as the Chemical Coagulant ................................. 97
Horizontal Layer Sampling, Pilot Unit .................................................. 97

viii

A6:

A7:

A8:

A9:

Pilot Unit Phosphorus Reductions with No Chemical Additions .................... 98

Pilot Results Using Lime As The Coagulant .......................................... 100
Pilot Results Using Alum As The Coagulant .......................................... 103
Pilot Results Using Lime As The Coagulant .......................................... 103

ix

2.1:

2.2:

2.3:

3.1:

3.2:

3.3:

3.4:

4.1:

4.2:

4.3:

4.4:

4.5:

4.6:

4.7:

4.8:

4.9:

4.10:

4.11:

4.12:

4.13:

LIST OF FIGURES

Phosphorus Release from Soil and Plant Material to

Surface and Sub-surface Water ............................................................ 9
Bio-P Bacteria During the Anaerobic Phase ............................................ 17
Reactions between Colloidal Particles and Polymers ................................. 29
Manure System Flow Diagram for Green Meadow Farms ........................... 43
Typical Settling Patterns for Jar Tests ................................................... 46
Jar Test Sampling Pattern, Top View .................................................... 47
Pilot Unit .................................................................................... 49
Average Phosphorus Concentration Reduction Using Lime

as the Coagulant, Lab Tests ............................................................... 59
Lime Treatment Cost Vs Phosphorus Reduction Lab Tests .......................... 59

Average Phosphorus Concentration Reduction Using Alum

as the Coagulant, Lab Tests ............................................................... 63
Alum Treatment Cost Vs Phosphorus Reduction Lab Tests ...................... '. ..63
Average Phosphorus Concentration Reduction Using FeC13

as the Coagulant, Lab Tests ............................................................... 66
FeCl; Treatment Cost Vs Phosphorus Reduction Lab Tests ......................... 66
G Curves for Phipps and Bird Jar Test Apparatus ..................................... 71
SP Reductions with No Mixing or Chemical Treatment .............................. 74
TP Reductions with No Mixing or Chemical Treatment .............................. 74
Pilot Unit SP Reduction (or Concentration) with No Treatment ..................... 75
Pilot Unit TP Reduction (or Concentration) with No Treatment ..................... 75
SP Reductions with Mixing, but no Chemical Treatment ............................ 77
TP Reductions with Mixing, but no Chemical Treatment ............................. 77

4.14:

4.15:

4.16:

4.17:

4.18:

4.19:

4.20:

4.21:

4.22:

4.23:

Pilot Unit SP Reduction (or Concentration) with only Mixing ....................... 78

Pilot Unit SP Reduction (or Concentration) with only Mixing ....................... 78
SP Reductions with 5.28 g/L of Lime as the Chemical Coagulant .................. 80
TP Reductions with 5.28 g/L of Lime as the Chemical Coagulant .................. 80
SP Reductions with 3.17 g/L of Alum as the Chemical Coagulant .................. 82
TP Reductions with 3.17 g/L of Alum as the Chemical Coagulant .................. 82
SP Mass Balance, Treatment 3.17 g/L of Alum, Pilot Unit ........................... 83
TP Mass Balance, Treatment 3.17 g/L of Alum, Pilot Unit .......................... 83
SP Reductions with 1.06 g/L of FeC13 as the Chemical Coagulant .................. 85
TP Reductions with 1.06 g/L of FeCl3 as the Chemical Coagulant .................. 85

xi

A1 (111)
ATP
AWWA
BOD
Ca (11)
COD
DAP

Fe (III)
FeCl3

FS

MDEQ
MWPS
NTU
P.A.
PAM’s
PHB
PPm
RTF

SP

LIST OF ABBREVIATIONS

Aluminum in the +III Oxidation State
Adenosine Triphosphate
American Water Works Association
Biochemical Oxygen Demand
Calcium in the +11 Oxidation State
Chemical Oxygen Demand
Diammonium Phosphate
Iron in the +III Oxidation State
Ferric Chloride
Fixed Solids
Velocity Gradient
Generally Accepted Agricultural Management Practices
Green Meadow Farms, Inc.
Michigan Department of Environmental Quality
MidWest Plan Services
Nephelometric Turbidity Units
Public Act
Synthetic polymers derivatives from polyarylamide
Poly-B-hydroxybutyrate
Part per million
Right to Farm Act

Soluble Phosphorus

xii

TP

TS

TSP

VS

Total Phosphorus
Total Solids

Triple Superphosphate
Volatile Fatty Acid

Volatile Solids

xiii

CHAPTER 1

INTRODUCTION

1.1 Industry Scope

The dairy industry is Michigan’s leading agricultural commodity with cash receipts
from the sale of milk totaling $729 million in 2000 (Michigan Agricultural Statistics,
2001). Michigan currently ranks 8th nationally in milk production. In 2000, there were
300,000 milk cows on 3,500 farms in Michigan. The average dairy cow in Michigan
produced 8,626 kg (19,017 lb) of milk in 2000, with a total state production for the year
of 2,588 million kg (5,705 million lb). While milk production continues to increase and
cattle numbers remain unchanged the total number of dairy farms in Michigan continues
to decrease.

A critical component of dairying is manure production. A full grown lactating cow
will produce approximately 67 L (17.7 gal) of manure per day (MWPS, 2000) or 24,455
L (6,460 gal) annually. The annual total nutrients contained in the manure of one
lactating cow are: 136 kg (300 lbs) of Nitrogen, 69 kg (153 lb) of P205, and 79 kg (175

lb) ofK20.

1.2 Statement of Problem

Simply stated, the problem is that dairy farms, regardless of operation size or
location, produce an immense amount of nutrients (nitrogen, phosphorus, and potassium)
in the manure. Manure as excreted is 88% moisture (MWPS, 2000). Any additional
dilution water from rain, cattle waterer’s, or cleaning water further dilutes the manure

slurry. The end fate of manure on most dairy farms is land application to fallow ground.

Two concerns arise from land application regarding phosphorus in the manure. The first
concern deals with applying liquid dairy manure to land with tile drainage. Field tile
serves as a direct conduit to fresh water. Saturated soils or well aerated soils with
fissures and wormholes, may allow liquid manure to move very quickly to the tile drains
and then to surface water. The second concern is with eroded sediment reaching surface
water. Phosphorus in its stable form is anionic (negatively charged) and tends to adsorb
to the cationic clay particles and iron minerals in the soil solution. Due to biological,
chemical, and climatic changes in the soil and surrounding environment, phosphorus is
continuously cycled in the soil solution. Often, soil erosion carries soil particles and
attached nutrients until deposited in surface waters.

The real concerns arise when the phosphorus reaches the surface water through either
drainage or surface water. Phosphorus is the limiting nutrient in the growth of algae.
Phosphorus in excess of 0.02 ppm can cause elevated algae populations and accelerate
the natural eutrophication of surface waters (Sharpley et al., 1999). In Michigan, surface
water is of the highest priority since the Great Lakes system contains 20% of the world’s
fresh water (Copeland, 1996). In 1981, the Michigan Legislature enacted the Right to
Farm Act (RTF), PA. 93. The act was designed to protect producers from nuisance
lawsuits by setting voluntary practices to ensure proper management of natural resources.
The practices were written so that, if followed by agricultural producers, environmental
quality would not be degraded. The practices, also known as GAAMP’s (Generally
Accepted Agricultural and Management Practices), provide guidance for manure
management and utilization. For example, current voluntary guidelines call for no

application of manure to ground that has a Bray P1 test of 150ppm (300 lb/acre) or

greater. The traditional practice of disposing of manure in the least cost fashion has
elevated soil phosphorus levels above 150 ppm on fields surrounding livestock
operations. The 150 ppm phosphorus level is deemed sufficient to meet crop needs, but

not so high as to have large quantities of soluble phosphorus free in the soil solution.

1.3 Proposed Solution — Chemical Phosphorus Separation

The present limits for manure application to the cropland, based on phosphorus
concentration, reduce the application methods and management options available to
producers. Utilizing a phosphorus reduction practice, like chemical phosphorus
separation, before storage creates a liquid stream relatively low in phosphorus and a solid
(sludge) stream with a high phosphorus concentration. In addition, chemical phosphorus
separation has potential to add a profit center to the dairy business by creating a nutrient
rich organic material that can be sold or used to replace commercial fertilizers in the
cropping program.

Municipal and industrial wastewater treatment systems have long had to address the
concern for nutrients in treated wastewater streams. Many approaches to the problem of
nutrient removal from effluent have been developed and implemented over the years.
Investigating the application of wastewater technologies to liquid dairy manure may offer
know-how and information to aid in the development of a system or systems to better

manage and reclaim the phosphorus.

1.4 Objectives

Nutrient management is quickly becoming a top priority in animal agriculture. In
Michigan phosphorus is the primary nutrient of concern. Phosphorus management prior
to manure storage is a relatively untested area that presents an opportunity for improved
environmental quality and profitability. Based on this, the objectives of this project are

as follows:

1) To evaluate and characterize the effluent stream following the sand and

solid/liquid separation systems.

2) To compare the effectiveness of various chemical coagulants, under
laboratory conditions, on the coagulation and reduction of phosphorus in the

liquid fraction.

3) To apply laboratory findings to a pilot unit under field conditions to see if

laboratory results translate to a larger scale reactor.

4) To evaluate the economic viability of a chemical treatment system.

1.5 Thesis Organization

Chapter 2 discusses the current methods for phosphorus removal and management in
municipal and industrial wastewater treatment. In addition, recent efforts to reduce
phosphorus concentrations in liquid dairy manure are also presented. Chapter 3 focuses
on the laboratory methods used to characterize the manure stream and to analyze the

phosphorus reduction efforts. The test procedures used in the laboratory and pilot tests

are also considered. The results from laboratory and field tests using the pilot unit are
presented in Chapter 4. Chapter 5 offers a summary of the study in addition to

conclusions drawn from the project.

CHAPTER 2

LITERATURE REVIEW

2.1 General Comments

If phosphorus use continues to increase, worldwide phosphate reserves are expected
to be completely depleted near the end of the next century (Driver, 1998). Globally,
agriculture uses 85% of the total phosphorus extracted annually for commercial fertilizers
and feed additives (Greaves, 1998). With agriculture leading the way in phosphorus use,
it is the likely industry to target for phosphorus reduction or recovery programs.
Phosphorus in agricultural fertilizers is one area targeted. Educational programs,
financial constraints, and activist groups are helping to reduce over-fertilization of
croplands. These same pressures are pushing livestock producers to examine how
phosphorus is fed and manure is managed. Animal nutritionists have made advances in
reducing the use of phosphorus concentrates in diets, but a large portion of the
phosphorus fed to livestock remains indigestible and is excreted in the feces. Treatment
and management of animal manure is where improvements in the removal, reuse, and
management of phosphorus must be made.

With the passing of the Clean Water Act in 1972, municipal and industrial
wastewater treatment systems were forced to meet strict standards for discharge to the
waters of the United States. Wastewater treatment plants employed many diverse
processes for removing phosphorus and other nutrients from the waste stream. Many of
these technologies have application potential for dairy manure. In the Great Lakes

region, wastewater treatment plants must follow stringent guidelines. Michigan’s

wastewater treatment facilities must achieve a maximum monthly average of 1 mg/L of
total phosphorus in the efiluent stream (MDEQ, 1999).

Phosphorus removal systems fall into two broad categories, biological and
chemical. Biological phosphorus removal involves two stages, anaerobic digestion
followed by an aerobic treatment. On the other hand, chemical phosphorus removal
involves the addition of positively charged ions such as lime, ferric chloride, alum, or
organic polymers, all of which bind to the phosphate anions forming large dense particles
that settle out of suspension. Mechanical solids separation has been investigated as a

means for phosphorus removal in agricultural livestock systems (Converse, 2000).

2.2 Agricultural Phosphorus

Since the introduction of commercial fertilizer, manure has long been thought of as a
waste material with little value - a byproduct of milk production that should be handled,
stored, and disposed of incurring the least expense to the dairy operation. In the mid-
1990’s, due to environmental pressure and the increased emphasis on profitability and
efficiency, livestock producers began to view manure as a valuable fertilizer and soil
amendment. Manure is a rich source of organic matter, nitrogen, phosphorus, and
potassium. Agriculture is the world leader in phosphorus consumption and the United
States is the largest consumer at 13% of the annual global phosphate. Western Europe is
second using a combined 12% (British Sulphur Publishing, 1998). The majority of the
phosphate used in agriculture is in commercial fertilizers, but a significant amount is used

in the formulation of rations for livestock and poultry. Recovery and reuse of phosphorus

excreted in the feces of livestock and poultry is essential for the sustainability of the
world’s phosphorus supply, surface water quality, and a safe and economic food supply.
A study conducted in 1995 on the nutrient balance of Michigan’s cropland reported
that Michigan is a phosphorus deficient state without the use of commercial fertilizer
(von Bernuth and Salthouse, 1999). Using manure as the only source of fertilizer,
Michigan would be in a deficit in phosphorus by 24 kg/Ha (21 lbs/ac). The overuse of
commercial fertilizers causes an excess of 15 kg/Ha (13 lbs/ac) of phosphorus. Through
better management, manure nutrients can be harvested and exported for use in deficient

areas.

2.2.1 Phosphorus Transport from Agricultural Fields

Phosphorus is lost from agricultural fields by two processes, surface runoff and
subsurface flow. Runoff events carry two forms of phosphorus, that which is bound to
sediment and that which is dissolved in water. Sharpley et a1. (1992) reported that 60 to
90 percent of the phosphorus lost to runoff is carried by sediment. Dissolved (soluble)
phosphorus released from soil particles and decomposing plants comprises the remaining
portion of the phosphorus lost to runoff. Soluble phosphorus is immediately available for
aquatic plant and animal use, whereas phosphorus bound to sediment is a long-term
source of phosphorus not accessible for utilization until released as soluble phosphorus
(Ekholm, 1994). Subsurface flow contributes to soluble phosphorus loss in soils with
low phosphate holding capacities (Cation Exchange Capacity) or where rapid flow
follows macropores and worrnholes. Figure 2.1 depicts the routes of phosphorus loss

from soil and plants.

2.2.2 Agricultural Phosphorus and Water Quality

It is important to remember that runoff from agricultural fields is only one of several
factors that influences phosphorus levels in surface water. The three main factors that
influence the supply of soluble phosphorus in surface water are biological turnover,
sediment exchange, and phosphorus input from runoff and discharge. Biological
turnover and sediment exchange can be classified as recycling of phosphorus within the
biological system. The third factor is the only input of phosphorus into the aquatic
system. Furthermore, discharge and runoff are not strictly limited to agriculture. Other
sources include industry, wastewater treatment plants, and golf courses, just to name a

few.

FIGURE 2.1: Phosphorus Release from Soil and Plant Material to Surface and
Sub-surface Water (Sharpley, et al., 1999)

See Michigan State University, Department of Agricultural Engineering Library

Research on phosphorus in livestock wastes has approached the subject from the
standpoint of water quality. Water quality is a top concern for both society and the
agricultural industry. Excess phosphorus in surface water wreaks havoc on the natural
cycles and habitats. Phosphorus levels exceeding 0.02 ppm (Sharpley et al., 1999) in
surface waters have been shown to significantly increase the rate of eutrophication or the
natural aging of lakes and streams. Phosphorus contained in the runoff from cropland has
been linked to algae blooms that can lead to fish kills and/or neurological damage in
humans exposed to the toxins secreted by the algae (Burkholder et al., 1992). In addition
to the water quality concerns, the depletion of the world’s phosphorus reserves is forcing
the entire agriculture industry to look for more conservation of phosphorus in agricultural

cycles.

2.3 Physical Separation

Physical separation of manure solids and nutrients, primarily phosphorus and
potassium, from manure effluent is based on size and density (Day, 1998). Physical
separation is not only the most cost effective and simplest method of separation, it is also
an essential characteristic of biological and chemical floc removal. Solid-liquid
separation methods include settling (sedimentation), evaporation, and mechanical

separation.

2.3.1 Settling

Suspended nutrients have a natural propensity to settle, as there density is

generally greater than the density of water. Four types of settling have been identified in

10

TABLE 2.1: Types of Settling Phenomena Involved in Wastewater Treatment
(Metcalfand Eddy, 1991)

Type of settling
phenomenon

Description

Application/occurrence

 

Discrete particle
(type 1)

F locculant
(type 2)

Hindered, also
called zone

(type 3)

Compression
(type 4)

Refers to the sedimentation of
particles in a suspension of

low solids concentration. Particles
settle as individual entities, and
there is no significant interaction
with neighboring particles

Refers to a rather dilute
suspension of particles that
coalesce, or flocculate, during
the sedimentation operation. By
coalescing, the particles increase
in mass and settle at a faster rate

Refers to suspensions of
intermediate concentrations, in
which interparticle forces are
sufficient to hinder settling

of neighboring particles. The
particles tend to remain in fixed
positions with respect to each
other, and the mass of particles
settles as a unit. A solids-liquid
interface develops at the top of
the settling mass

Refers to settling in which

the particles are of such
concentration that a structure
is formed, and further settling
can occur only by compression
of the structure. Compression
takes place from the weight

of the particles, which are
constantly being added to the
structure by sedimentation from
the supernatant liquid

11

Removes grit and sand particles
from wastewater

Removes a portion of the
suspended solids in untreated
wastewater in primary settling
facilities, and in upper portions of
secondary settling facilities. Also
removes chemical floc in settling
tanks

Occurs in secondary settling
facilities used in conjunction
with biological treatment facilities

Usually occurs in the lower layers
of a deep sludge mass, such as
in the bottom of deep secondary
settling facilities and in sludge-
thickening facilities

wastewater: i) discrete, ii) flocculant, iii) hindered (also called zone), and iv) compression
(Metcalf and Eddy, 1991). Sedimentation will generally involve multiple settling types at
different stages and times. In some instances, all settling types may occur
simultaneously. Table 2.1 contains descriptions of the four settling types.

Naturally occurring sedimentation has an impact on total solids and nutrient
content of liquid dairy manure in storage. Jones and Brown (2000) reported reductions in
effluent total solids of 18% to 35% and total phosphorus of 47% for a two-hour settling
period. In other research, twenty minutes of unaided settling was found to remove 65%
of the total solids and 60% of the total phosphorus in simulated dairy flushwater (Barrow
et al., 1997). The literature, however, does not discuss the stability of the naturally
settled sludge or management of the nutrients contained in the sludge. Lorimore et al.
(1995) conducted a sediment basin study on feedlot runoff. It that study, it was
determined that settling basins with retention times of 10 to 100 minutes reduced total
solids by 39 to 53%. This study was conducted using beef manure from an open feedlot,
thus gravel picked up in the runoff may have an influence on the sediment efficiency.
Chastain et al. (1999) reported that liquid dairy manure in a simulated settling basin with
a retention time of 60 minutes reduced P205 in the effluent by 38%. In addition, he
reported that passing effluent from a screen separator through a settling basin removed an

additional 14.6% of the P205.

2.3.2 Mechanical Separation
Mechanical separation is an important treatment method for dewatering animal

manure. Dewatering produces liquid and solid fractions that can be better managed to

12

meet the needs of the producer. The liquids may be injected or irrigated, while the
solids can be composted or surface applied. Mechanical liquid-solid separators use
sedimentation, screening, centrifugation, and/or filtration to remove free water from
manure solids. Sloping screens, vibrating screens, screw presses, and centrifuges are
commonly used methods for liquid solid separation of dairy manure. Mechanical
separators function by exploiting differences in particle size and density to achieve the
desired products of separate solid and liquid streams. Mechanical separation, as with
most treatment options, is challenged by non-uniform characteristics and production of
manure due to differences in species, genetics, age, rations, collection method, dilution,
and weather.

Theoretical solids removal using mechanical separation for dairy manure slurries
is in the range of 64 to 84% according to Zhang and Westerman (1997). The addition of
chemicals to coagulate dissolved solids can result in removal efficiencies over 85%.
Hegg et al. (1981) used three screens, vibrating, stationary, and rotating, to remove solids
from dairy manure. The rotating, stationary, and vibrating screens removed 8.25%, 7%,
and 12% of the dry matter, respectively. In this study, nutrient removal was not
evaluated. Huijsmans and Lindley (1984), evaluated the usefirlness of the stationary
screen for removing solids from liquid dairy manure. They found that the static screen
with or without a rinse bar was only able to remove approximately 25% of the total
solids. In a more recent study, Zhang (1997), separation efficiencies for liquid dairy
manure on stationary and vibrating screens were reported to be 49% and 8 to 16%,

respectively. Nutrient removal efficiency for dairy manure was not presented in this

13

study, however, Chastain et al. (1999) stated that 53.1% of the P205 was removed from
liquid dairy manure by a static screen.

In 2000, Converse presented the results of research done on the solids and nutrient
removal using screw presses. Converse found that the two screw presses (FAN and
Vincent) removed 23.8% and 33.4% of the total solids. The phosphorus (P205) removal
efficiency of the screw press was reported to be 5.7% and 9.7%.

Zhang (1997) states that the economics of solid-liquid separation are based on

ease of manure handling, odor control, nutrient management, and manure solids value.

2.4 Phosphorus Removal and Recovery

Past research has focused on binding up phosphorus at various points in the
manure or wastewater system. Phosphorus has been bound and settled in storage, thus
creating a phosphorus sink in the sludge that settles out during storage. Others have
attempted to chemically bind phosphorus in the field. Another approach to phosphate
management in the manure stream is that of removal and reuse before storage. In the
following sections past research on biological and chemical phosphorus removal will be
discussed. Both biological and chemical phosphorus removal allow for several methods
for managing and reusing of removed phosphorus. Removal, recovery, and reuse of
phosphate in livestock manure is a sustainable and environmentally sound approach to

manure management.

14

2.4.1 Biological Phosphorus Removal

Literature on biological phosphorus removal dates back to India in the late 1950’s.
Srinath et al. (1959) observed the phenomenon that would become known as “luxury
uptake”, the uptake of excessive amounts of phosphorus by microorganisms in
wastewater when exposed to aerobic conditions following an anaerobic period.
Biological phosphorus removal is dependent on a two-stage system where anaerobic
conditions are followed by aerobic treatment. Under these conditions, microorganisms
can hold approximately 12% phosphorus on a dry weight basis. Van Loosdrecht (1998)
states that the advantage of biological phosphorus removal over chemical phosphorus
removal is that biological removal systems are highly selective and can achieve low
phosphorus concentrations in the system effluent. The drawbacks to biological phosphate
removal are system management and collection and utilization of the biomass containing
the phosphorus. Management issues associated with the biological system include i)
equipment maintenance, ii) monitoring pH, temperature, and acetate levels, iii) correcting
for fluctuations in pH, temperature, and acetate, and iv) assuring homogeneity of input

stream and proper detention times.

2.4.2 Mechanisms of Biological Phosphorus Removal

Many references including Metcalf and Eddy (1991) and Van Loosdrecht (1998)
describe biological phosphorus removal as a two-step process, an anaerobic phase and an
aerobic phase. In the anaerobic phase fatty acids accumulate and are stored in the cells,
polyphosphate serves as the energy source. Byproducts of this step include methane and

limited denitrification of existing nitrate. During the aerobic phase, cell growth occurs

15

with fatty acids serving as the energy source. It is during this period of cell growth that
the “luxury uptake” of phosphorus occurs. At the same time, ammonia is converted to
nitrate (nitrification). In the following sub-sections, the anaerobic and aerobic phases of

biological phosphorus removal will be examined more closely.

2.4.2.1 Anaerobic Phase

Acinetobacter is the primary organism in the phosphorus removing bacteria group
know as “bio-P bacteria”. During the anaerobic phase, microorganisms use stored
polyphosphate for the production of adenosine triphosphate (ATP) (Van Loosdrecht,
1998). In the absence of oxygen or nitrate, the “bio-P bacteria” amass volatile fatty acids
(VF A’ s) using polyphosphate as the substrate. The VFA’s storage under anaerobic
conditions will serve as a substrate (energy source) for the “bio-P bacteria” during the
aerobic phase, thus giving them an advantage over hetertorphs during aeration. The
hydrolysis of polyphosphate supplies energy for polymerization of poly-B-
hydroxybutyrate (PI-IB). In addition, the hydrolysis of polyphosphate releases
phosphorus during the anaerobic stage, the released phosphorus accumulates until it is
shuttled out of the cell by the pH gradient sensitive “carrier”. Anaerobic conditions are
favorable for the formation of PHB, which serves as a reserve for carbon and energy.
Cell membrane activity is strongly influenced by pH, therefore, the transport and ratio of
VFA uptake and phosphorus release is dependent on pH (Smolders et al., 1994). Figure

2.2 presents the cycle of the bio-P bacteria during the anaerobic phase.

16

FIGURE 2.2: Bio P Bacteria During the Anaerobic Phase (Hashsham, 2000)
See Michigan State University, Department of Agricultural Engineering

2.4.2.2 Aerobic Phase

The energy from the hydrolysis of PHB during the aerobic phase is used in the
growth of new biomass and formation of polyphosphate. Normal metabolic phosphorus
uptake meets the microorganisms’ needs for maintenance, synthesis, and energy
transport. Excessive polyphosphate development serves as a phosphorus reserve for
future phosphate needs. The wasting or removal of the excess biomass (sludge) produced
during the aerobic stage is the route by which phosphorus is removed from the waste

stream.

17

For years, biological phosphorus removal has been an effective method for
industrial and municipal waste treatment. 0n the other hand, very little is known about
biological phosphorus removal for animal wastes. Due to the differences in animal and
municipal wastes a direct transfer of application could very well fail. Animal manures
have nutrient levels that are several orders of magnitude higher than municipal wastes. In
addition, municipal wastes are much lower in total solids content than animal wastes.
Table 2.2 shows a comparison of municipal and dairy wastewater.

The effects, benefits, and disadvantages of anaerobic and aerobic treatment have been
well documented for several types of animal wastes. However, very little information
exists on biological phosphorus treatment of animal waste and even less information
exists on dairy manure treatment. Recent papers by Sukias, J.P.S. et a1. (2000), Moser,
MA. et al. (2000), and Zhang RH. et al. (2000) looked at the application of anaerobic
and aerobic conditions for treating dairy manure.

Biological phosphorus removal is a complex process involving several steps and
intensive management. Another disadvantage is the high capital cost associated with new

biological treatment facilities.

2.5 Mechanisms of Chemical Phosphorus Removal

Chemical addition as a means of nutrient removal and purification have been used
since the late nineteenth century in both water and wastewater treatment. Chemical
nutrient removal is dependent on three steps: i) coagulation, ii) flocculation, and iii)

settling of the aggregated floc (Francois, 1984). Settling and sedimentation of the floc

18

has been discussed in the Physical Separation section of this chapter. The following sub-
sections contain a discussion of coagulation and flocculation as it relates to nutrient

removal from liquid dairy manure.

TABLE 2.2: M
Parameters

Wastewater Vs D
1

Manure

         

 

Wastewater Wastewater

to Black Brown to Black
15

37 61
otal N 6

otal P 3
otal Solids 95

Solids 81
Southwest Biotechnology and Infomatics Center

fMid-West Plan Service-18, 2000
Laboratory experiments conducted during this Thesis project
2.5.1 Coagulation and Precipitation

The terms coagulation and flocculation are used interchangeably in the water
treatment literature. Coagulation and flocculation, in theory, refer to the aggregation of
particulates. Precipitation is the formation of particulates.

The goal of chemical coagulation is to increase the particle size of suspended
material. Coagulation is dependent on two factors, charge neutralization and interaction.
Essentially, coagulation is the destabilization of colloidal particles by the addition of
coagulants that reduce the repulsion between particles. O’Melia (1970) refers to the
Schulze-Hardy rule which states that coagulation is brought about by the ion of opposite

charge of the colloid and that the efficacy of this ion increases markedly as its charge or

19

valence increases. According to Schulze-Hardy, each charge on the chemical ion brings
about a ten-fold increase in its coagulation ability. As the charge on the coagulant goes
from 1 to 2 to 3 its coagulating ability goes from 10 to 100 to 1000 (O’Melia, 1970).

Coagulation is the process by which dense aggregates are formed by the assembly of
suspended particles with multivalent ions or organic polymers. In wastewater treatment
systems the multivalent ions used for coagulation are generally cationic. After
coagulation, the increased densities of the newly formed aggregates cause them to settle.
If coagulation alone does not achieve the desired results, the coagulated suspension may
pass into a flocculation system where the destabilized particles form larger, denser flocs
with the addition of a polymer.

Coagulation takes place in a rapid mix chamber, the chamber is used to create a
homogenous mixture and ensure contact between colloids and ions or polymers. Hudson
(1967) states that industrial plants use powerful mixing devices with rapid mix chamber
detention times of not greater than thirty seconds. The design of rapid mixing for
coagulation is based on the velocity gradient (G). The velocity gradient is dependent on
the mixing power input, the fluid viscosity, and the fluid volume. The velocity gradient
equation developed by Camp and Stein (1943) has become the standard for municipal
and industrial treatment plant mixing design. Table 2.3 contains average detention times
and velocity gradients for wastewater treatment. The equation for the velocity gradient is

(Sievers, 1989):

20

(2.1)
where G = mean velocity Gradient (l/s)
P = power (fi°lb/s)
u = dynamic viscosity (res/a2)

V = volume (ft3)

Sievers (1989) studied velocity gradients in one percent (TS) animal manure
slurries. Samples were agitated in a jar test apparatus for 20 minutes, then allowed to
settle for 100 minutes. Sievers reported that the optimum velocity gradient (G) for
chemical addition to dairy manure was 22.3 s". Detention times in this trial ranged from
240 seconds for iron additions to 480 seconds for chitosan. Sievers also reported that

chemical coagulation in wastewaters with high organic solids concentrations required less

mixing.

2.5.2 Flocculation

As defined by Hemenway (1968), flocculation is the physical mixing of particles
destabilized by coagulation in order to form larger floc structures through contact.
In contrast to the rapid-mix chamber utilized for coagulation, which uses high power with

a short retention time, a flocculation basin uses low power input with a longer detention

21

time. Insufficient mixing may result in poor cluster (floc) formation, thus reducing solids

and nutrient removal (Sievers, 1989). Excess mixing may cause the flocculation process

TABLE 2.3: Typical Velocity Gradient (G) and Detention Time Values for
Wastewater Treatment Processes (Metcalfand Eddy, 1991)
Range of values

 

Process Detention time G value, s-1
Mixing

Typical rapid mixing operations

in wastewater treatment 5 - 20 s 250 - 1,500

Rapid mixing in contact
filtration processes < 1 - 5 5 1,500 - 7,500

Flocculation
Typical flocculation processes

used in wastewater treatment 10 - 30 min 20 - 80

Flocculation in direct
filtration processes 2 - 10 min 20 - 100

Flocculation in contact

filtration processes a 2 - 5 min 30 - 150
aFlocculation occurs within granular-medium filter bed

to become ineffective. This occurs when the shear forces cause the floc to disintegrate
because the cohesion strength of the particles has been exceeded. Traditionally the
velocity gradient ranges from 30 to 60 s'1 for good floc formation in municipal and

industrial water treatment as seen in Table 2.3 .

2.5.3 pH Adjustment
It is well understood that pH adjustment of the waste stream can have a significant
influence on the effectiveness of chemical coagulants (O’Melia, 1969). In certain cases,

coagulation or flocculation can be induced by simply adjusting the pH through the

22

addition of acids or bases. Sievers et al. (1994) investigated the effects of pH adjustment
on settling and turbidity removal. Increasing the pH of dairy wastewater and poultry
litter was found to have little effect on water clarity. 0n the other hand, increasing the
pH of swine manure drastically reduced turbidity. Metcalf and Eddy (1991) state that
there is generally no relationship between turbidity and suspended solids or phosphorus.
pH adjustment alone does not appear to be the answer to phosphorus removal from dairy
manure, however it may play a role in influencing and improving the efiiciency of other

coagulants.

2.5.4 Solids and Phosphate Removal using Chemical Additions and
Organic Polymers

The most commonly used chemical precipitants in phosphorus removal are calcium
[Ca(II)], aluminum [Al(III)], and iron [Fe(III)] and organic polymers. The addition of

multivalent metal ion salts to wastewater forms precipitates with soluble phosphates. The

TABLE 2.4: Chemicals Used in Wastewater Treatment (Metcalfand Eddy, 1991)

 

 

Molecular Density, Iblt’t3
Chemical Formula weight Dry Liquid

Alum AI2(SO..)3 * 18H2Oal 666.7 60 - 75 78 - 80 (49%)

Al2(804)5 * 14H20'I 594.3 61 - 75 83 - 85 (49%)
Ferric chloride EeCl3 162.1 84 - 93
Ferric sulfate Fe2(804)3 400

Fe2(SO4)3 * 3H2O 454 70 - 72
Ferrous sulfate FeSOi * 7H2O 278 62 - 66
Lime Ca(OH)2 56 as CaO 35 - 50

 

I'Number of bound water molecules will vary from 13 to 18
Note: Ib/fi3 x 16.0185 = kg/m3

23

increased molecular weight of the precipitates enhances settling. Table 2.4 from Metcalf
and Eddy (1991) presents some common forms of the metal salts used in wastewater
treatment. Likewise, polymers are anionic, cationic, or nonionic and work by bridging
particles into larger aggregates.

In wastewater treatment, there are three strategies for phosphate removal from the
waste stream, including pre-precipitation, co-precipitation, and post-precipitation. Pre-
precipitation involves the addition of coagulants or flocculants to the raw waste stream,
the phosphate is then settled out in the primary clarifier. Co-precipitation occurs when
chemically coagulated phosphate is removed with biological sludge following a
biological treatment such as anaerobic digestion. Sievers et al. (1994) discuss using
chemical coagulants to treat swine manure for volatile solids removal following
anaerobic digestion. Post-precipitation is the addition of chemical coagulants following

secondary settling.

2.5.4.1 Calcium

Calcium in the form of lime is frequently used to treat wastewater for solids and
phosphate removal. Lime added to wastewater first reacts with the natural bicarbonate
alkalinity to form CaC03. Calcium ions react with phosphate ions above pH 10 to form
hydroxylapatite (Calo(P04)5(0H)2), a precipitate (Metcalf and Eddy, 1991). The

phosphate-calcium reaction is shown by equation 2.2:

roca+2 + 6P0;’ + 20H‘ <:> Ca,,(P0,),(0H), (2.2)

24

The alkalinity of the wastewater is the main factor that influences the dosage
needed. Metcalf and Eddy (1991) state that a good rule of thumb for calcium phosphate
precipitates is that lime must be added at a rate of 1.4 to 1.5 times the total alkalinity.
Lime as a coagulant can be used in a pre-precipitation or post-precipitation system.
Barrow et al. (1997) reported that the addition of hydrated lime to a simulated dairy flush
stream reduced total solids by 72.3%. In this same study, little difference was seen in the

amount of total solids and nutrients removed by various levels of calcium addition.

2.5.4.2 Aluminum

Aluminum in the form of liquid alum (Al2(SO4)3-14-18H20) is a common
coagulant used in wastewater treatment. Unlike lime, alum will precipitate phosphate in
a molar ratio of one to one. In addition, aluminum ions are most effective in the neutral
to slightly acidic range. The phosphate precipitation reaction that occurs when

wastewater is treated with alum can be written as follows:

Al+3 +H,,P0;"3 <:> AIPO4 +nH+ (2.3)

Due to the many variables including pH, alkalinity, trace elements, and organic
matter that influence chemical coagulation, equation 2.3 cannot be used to predict the
alum dosage without bench scale confirmation. Laboratory confirmation of chemical
doses is done using jar tests with the actual wastewater to be treated. A more in-depth

description of jar testing is found in the Chapter 3, Experimental Methods.

25

A study conducted by Jones and Brown (2000) used alum to treat dairy wastewater.
During lab tests, it was observed that a 3 g/L dose of alum reduced ortho-phosphorus in
the effluent by 93 -99%. The study reported 81% total phosphorus removal using a dose
of 3 g/L of alum. Jones and Brown (2000) indicated that at treatment levels higher than
3 g/L the total phosphorus removal actually decreased. In 1998, Zhang and Lei reported
that additions of aluminum sulfate improved settling of manure solids by promoting

coagulation.

2.5.4.3 Iron

Iron reacts with phosphate in wastewater in much the same manner as aluminum.
Several forms of iron are used to treat wastewater for phosphorus removal, the most
common are Ferric Chloride (F eC13), Ferric Sulfate (Fe2(SO4)3), and Ferrous Sulfate

(F eSO4-7H20). Phosphate precipitation using iron is represented by equation 2.4:

Fe” + HJ’Of3 <:> FePO4 +nH+ (2.4)

As with alum, one mole of iron will precipitate one mole of phosphate.
Furthermore, the iron-phosphate reactions are also hampered by side reactions, thus
laboratory testing should be done to confirm equation 2.4. Unlike aluminum, iron works
best in acidic conditions (pH < 6).

Traditionally, iron has been the most popular of the three cations for wastewater
treatment. Barrow et al. (1997), Sievers et al. (1994), and Zhang and Lei (1998) all

looked into the usefulness of iron for reducing total solids and nutrients in the dairy

26

wastewater stream. Barrow et al. (1997) simulated dairy flushwaters with 0.5, 1.0, and
1.5% total solids to test the usefulness of iron for solids and nutrient removal. Barrow
reported that ferric chloride was more effective than ferric sulfate and that 278 mg/L of
ferric chloride reduced phosphorus in the effluent by 89%. An interesting finding by
Zhang and Lei (1998) is that large solids in animal wastes did not hinder the actions of
chemical coagulants. In the same study, Zhang and Lei (1998) found that the optimum
dose of chemical coagulant is related to the solids content. The optimum dose for a waste
stream with 1.6% total solids was found to be 1000 mg/L.

As with phosphate, iron has been found to be an effective means for removing
solids from animal waste streams. Barrow et al. (1997) found that 27 8 mg/L of Fer
reduced total solids by 88.8%. Fer with 358 mg/L of calcium oxide (CaO) increased
solids removal to 93%. Sievers et al. (1994) used FeC13 to remove volatile solids from
1% total solids simulated waste streams of dairy, swine, and poultry manure. It was
found that FeC13 removed 75% of volatile solids from dairy and swine wastewater, but

was far less effective for poultry manure.

2.5.4.4 Polymers

Unlike the ionic coagulants discussed previously, organic polymers are commonly
used as flocculating agents in wastewater treatment. The polymers can be natural or
synthetic, can carry a charge or not, and the molecular weight can be manipulated to meet
the desired treatment need. Natural polyelectrolytes are biological derivatives of starch
products, cellulose, or alginates. Synthetic polymers are monomers that have been

polymerized into high molecular weight chains. Zhang and Lei ( 1998) state that the

27

majority of synthetic polymers are derivatives of polyarylamide (PAM’s).
Polyelectrolytes can posses a charge, positive or negative, or can be charge less
(nonionic). Molecular weights of organic polymers are generally in the range of 104 to
10". Polymers have two advantages over metal salts, they are at least partially
biodegradable and they do not interfere with further biological processing. However,
polyelectrolytes are substantially more expensive at $7.48/kg than metal salts, which cost
$0.40/kg (Sievers et al., 1994).

Polymers act by several modes of action as seen in Figure 2.3 from O’Melia
(1969). The most common is the floc formation, Reaction 2A., where both coagulation
and bridging take place. Adding a polyelectrolyte with opposite charge of the wastewater
particles coagulates the wastewater. Wastewater particles are generally anionic, thus
cationic polymers are used to counteract the charge. Coagulation is carried out in the
rapid mix chamber which has short retention time, but uses large amounts of power to
assure complete mixing. Bridging occurs in the flocculation chamber and is the
attachment of two or more particles to the same polymer chain. As more particles
become attached and intertwined in the polymer chain a new particle known as a “floc”
forms. Flocculation basins use much less power for mixing, but the wastewater has a
longer detention time. Hemenway and Keshavan (1968) suggest velocity gradients of 30
to 60 s'1 for floc formation. They also state that gradients of greater than 75 ft 3'1 cause

excessive shear and may cause the polymers to break apart.

28

FIGURE 2.3:Reactions between Colloidal Particles and Polymers (O’Melia, 1969)
See Michigan State University, Department of Agricultural Engineering Library

Jones and Brown (2000), Zhang and Lei (1998), and Sievers et al. (1994) all used
commercially available polymers to treat animal wastes for solids and nutrient removal.
Jones and Brown were able to reduce total solids by 85% with polymers, but found little
reduction in orthophosphorus using only cationic PAM’s. Combining the polymer with
alum treatment reduced the amount of polymer used and significantly improved solids
and orthophosphorus removal. Zhang and Lei (1998) reported similar results using
combinations of ferric chloride and synthetic polyelectrolytes. Sievers et al. (1994)
reported 7 5% volatile solids removal using chitosan, a natural polymer, from cattle

slurries.

29

CHAPTER 3

EXPERIIVIENTAL METHODS

3.1 General Comments

This chapter describes and discusses the techniques and methods utilized to
characterize liquid dairy manure and to test the ability of various additives to coagulate
and settle phosphorous. The American Water Works Association (AWWA) standard
procedures for determining soluble phosphorous (SP), total phosphorous (TP), chemical
oxygen demand (COD), total solids (TS), volatile solids (VS), fixed solids (F S), and
turbidity, were used throughout the phosphorous separation study to characterize the
manure stream and determine removal efficiencies. Workers in both industrial and

municipal wastewater treatment industries accept the AWWA methods.

3.2 Standard Techniques and Procedures
3.2.1 Soluble Phosphorus (SP)

The technique to determine the soluble phosphorus (SP) is AWWA (1993) section
4500-P, direct phosphorus analysis. This analysis looks strictly at the reactive (soluble)

phosphorus in the sample of wastewater.

3.2.1.1 Materials

The following equipment was used to determine the soluble phosphorus content
of the liquid dairy manure:

250 ml Erlenmeyer Flasks

1.6 Micron Glass Fiber Filter

30

Fischer Scientific Vacuum Pump, 1/3 Hp
Extech pH/mV/Temperature Meter

Hach test tubes

10 ml Pipette and Pipette Filler

Eye Dropper and Bottle

Milton Roy Spectronic Model and Spectrophotometer

3.2.1.2 Methodology

Soluble phosphorus is the measure of reactive phosphorus, primarily
orthophosphate, which responds to colorimetric tests without preliminary hydrolysis or
oxidative digestion. Reactive phosphorus can be dissolved or suspended. The
preparation procedure for soluble phosphorus analysis includes the following steps:

0 Manure samples are diluted 200 to 1 with deionized water. This level of dilution
is necessary due to the high phosphorus content of dairy manure and the relatively
small range of the stannous chloride colorimetric procedure.

0 The diluted sample is then vacuum filtered through the 1.6 micron filter. This
step removes the large suspended particulates in the sample.

0 100 ml of the filtered sample is measured into an Erlenmeyer flask and the
solution is allowed to reach room temperature.

Colorimetric analysis of the 100 ml filtered sample is carried out using the
Stannous Chloride Method, AWWA (1993), 4500-P D. Stannous chloride analysis

proceeds as follows:

31

o 4.0 ml of the Ammonium Molybdate Reagent I and 0.5 ml of Stannous Chloride
Reagent I are added to the 100mL filtered sample, care is taken to assure thorough
mixing between reagent additions.

- Color development is measured 10 minutes after reagents are added, but before 12
minutes.

Overcash et al. (1974) points out that ascorbic acid, stannous chloride, and
vanadomolybdate methods “yield essentially similar results for orthophosphate analysis
and have nearly the same variability.” The absorbance of the solution is measured
photometrically at 690 nm in the visible spectrum using a spectrophotometer.
Absorbance measurements are then compared to the calibration curve to get the actual

soluble phosphorus of the sample. Calibration curve preparation is discussed later.

3.2.2 Total Phosphorus

The analysis procedure used to measure total phosphorus (TP) is the Persulfate
Digestion procedure defined in the AWWA Standard Methods (1993), section 4500-P.
Persulfate digestion oxidizes organic matter present in the manure sample and releases

the bound phosphorus as orthophosphate.

3.2.2.1 Materials
The following equipment is used to determine the total phosphorus content of
liquid dairy manure:
250 ml Erlenmeyer Flasks

Corning Hotplate

32

Fume Hood

Extech pH/mV/Temperature Meter
Hach test tubes

10 ml Pipette and Pipette Filler
Eye Dropper and Bottle

Milton Roy Spectronic Spectrophotometer

3.2.2.2 Methodology

Total phosphorus is the colorimetric measure of the ortho-phosphate in the sample
following oxidation. The procedure for analyzing a sample for total phosphorus is as
follows:

0 Samples are diluted 200 to 1 with deionized water.

0 Sample digestion, 1 ml of sulfuric acid solution and 0.40 g of ammonium
persulfate are added to 50 ml of the diluted sample which is then gentle boiled
using the hot plate.

0 Boiling persists until a final volume of 10 ml is reached.

0 Digested sample are then diluted to 100 ml and cooled to room temperature.

0 Colorimetric analysis is then carried out using the Stannous Chloride procedure
discussed under the soluble phosphorus section.

Analysis results are then compared to the calibration curve to get actual

phosphorus concentrations.

33

3.2.3 Phosphorus and COD Calibration Curve Preparation

The calibration curve is essential to quantifying the results of colorimetric
analysis. The calibration curve is a reference point to make comparisons between
unknown phosphorus concentrations and known concentrations. In this project, five and

four point calibration curves were used for phosphorus and chemical oxygen demand

(COD), respectfirlly.

3.2.3.1 Materials
The materials needed to create a phosphorus calibration curves are the same as for

SP and TP analysis.

3.2.3.2 Methodology

The calibration curve is created by carrying a series of orthophosphate and COD
standards through the same methods used for SP and TP and COD analysis. Due to
treatment differences, separate curves are produced for SP and TP. The points for the
phosphate calibration curves are 0, 0.5, 1.0, 1.5, and 2.0 ppm. Similarly, the four point
COD curve is created with points at 0, 200, 500, and 1000 ppm. Sample analysis points
are then compared to the calibration line, the linear equation for the line is used to
calculate the actual phosphorus content of the sample. A new calibration curve is created
for every new set of standard reagents. Calibration curves with regression coefficients

smaller than 0.980 are considered erroneous, and a new curve is created.

34

3.2.4 Chemical Oxygen Demand

Chemical oxygen demand (COD), similar to biochemical oxygen demand, is the
measure of organic matter in wastewater. COD is the oxygen equivalent of the organic
matter content of a sample following oxidation using a strong chemical oxidizing agent in
an acidic medium at a high temperature (150°C 3: 2°C). Potassium dichromate is the

principal oxidizer. The COD oxidation reaction is represented as:

C,H,0, + 0,0;2 + H: Jfl—scwi + C02 + 11,0 (3.1)
Overcash, et al. (1974) states that COD is a reliable, quick, and reproducible measure of
oxygen demand in animal wastes. Sampling and pipetting errors, which are difficult to

control due to the nature of animal waste, in addition to errors associated with the test,

account for fluctuations in the results.

3.2.4.1 Materials
The materials utilized in COD analysis are:
HACH 25 tube COD Reactor
Mercury Thermometer
HACH High Range COD Vials (50 - 1500 mg/l COD)
Milton Roy Spectronic Spectrophotometer

Fume Hood

3.2.4.2 Methodology
The standard technique prescribed by the HACH Company for measuring COD
follows the AWWA Standard Methods (1993) for Closed Reflux Colorimetric Method,

508 C. COD analysis consists of:

35

o Preheating COD reactor to 150°C i 2 0C.

o 2 ml of the manure sample diluted 100 to 1 with deionized water is added to a
HACH COD vial.

o The sample and vial contents are mixed by inverting several times.

0 Vials are heated in COD Reactor for two hours.

0 The vial is removed from the heater and the colorimetric absorbance is measured
using a spectrophotometer with a wavelength of 620 nm in the visible spectrum.

The colorimetric analysis results are compared to a series of standards to get the

actual COD.

3.2.5 Hot Weighing

Solids content is analyzed using methods accepted by the AWWA (1993) and
described in sections 2540 B and E. The only change to the standard procedure is that
measurements are taken on a “hot basis” instead of “cold basis”. ‘Hot basis” weights are
taken immediately after removing the sample from the oven, “cold basis” weights are
taken after the sample is allowed to cool in a desiccant. “Hot basis” measurements are
preferable because of the elimination of the potential for a faulty desiccant allowing

moisture to accumulate on the beaker.

3.2.5.1 Materials
The following equipment is used to hot weigh samples:
Fisher Scientific Isotemp Oven Model 655°F (:tl °C)

Mettler AB 240 Balance $0.000] g

36

50 ml beaker

3.2.5.2 Methodology
The procedure for hot weighing sample is as follows:
0 Clean 50 ml beakers, stored in the drying oven for a minimum of twenty-four
hours, are weighed on the Mettler AB 240 Balance.
0 The balance is tared to account for the weight of the beaker and the moisture
accumulated while measuring.
0 Approximately 25 g of sample is measured into the 50 ml beaker, the sample

mass is recorded as msampre.

3.2.6 Total Solids Measurement

Total solids (TS) is a measure of the solid material remaining after the moisture is
evaporated in a oven with constant temperature between 103 and 105°C. The sum of the
TS and percent moisture content is equal to 100% of the sample weight. The procedure
for measuring TS is approved by the AWWA Standard Methods (1993), section 2540 B.
The only change to the standard method is that sample weights are measured on a “hot

basis” instead of a “cold basis” as discussed above.

3.2.6.1 Materials

The equipment used to measure TS is identical to the materials identified for hot

weighing.

37

3.2.6.2 Methodology

The standard procedure for determining TS is as follows:

0 Samples weighing between 25 and 50 g are weighed into 50 ml beakers using the
hot weight technique.

0 Samples are dried at temperatures between 103 and 105°C for a minimum of
twenty-four hours.

0 After the twenty-four hour drying period, the dried sample mass is measured and
recorded.

TS is the ratio of the mass of the dried sample to the mass of the original (wet) sample

(equation 3.2).

 

m
TS: d” *100 (3.2)

sample

where: TS = Total Solids, %
1ndry = Sample mass after drying, g
msamplc = Initial (wet) sample mass, g

3.2.7 Fixed and Volatile Solids Measurement

Adding the fixed solids (F S) and volatile solids (VS) gives the TS of the sample.
FS is the inorganic portion of the sample that remains after the sample has been ignited.
Conversely, the VS are composed of the organic material that is burned off during
ignition in the muffle firrnace. The procedure for measuring FS and TS is outlined in the

AWWA Standard Methods (1993) section 2540-E.

38

3.2.7.1 Materials
The equipment for measuring FS and VS is identical to that for hot weighing,
with the addition of a laboratory furnace with a peak temperature of 550°C. In this study

the following furnace was used:

Thermolyne Type 30400 Furnace (i1 oC)

3.2.7.2 Methodology
The technique used to determine FS and VS is:
0 Hot weigh samples as previously described.
0 Ignite samples in Thermolyne muffle furnace at 550°C (also known as ashing) for
a minimum of one hour.
0 Return samples to the oven to cool to between 103 and 105°C before weighing the

remaining ash.

The ash remaining after ignition constitutes the FS, or inorganic material, and can

be expressed as equation 3.3:

m

FS=£*100 (3.3)
m do,
where: FS = Fixed Solids, %
mash = Sample mass after ashing, g
mdry = Sample mass after drying, g

39

The portion of the sample vaporized during the ashing process is the VS (equation

3.4), and is calculated as:

 

m dry — mash
m day
where: VS = Volatile Solids, %
1ndry = Sample mass after drying, g
mash = Sample mass after igniting, g

TS is equal to the sum of the fixed solids (F S) and volatile solids (VS).

TS=VS+FS (3.5)

The PS (inorganic material) is the residue remaining after igniting the sample at
550°C for no less than one hour. Likewise, VS (organic matter) is the measure of the

sample weight lost during ignition.

3.2.8 Turbidity

Turbidity is the clarity of a sample of wastewater. Turbidity in wastewater
samples is caused by suspended matter such as clay, silt, organic matter, and inorganic
particles. Turbidity is a comparison of the light absorbed (scattered) by suspended
particles in a sample to the light scattered by a reference sample under the same

conditions. The light used in the measurement is a Tungsten-filament lamp with a light

40

travel distance of less than 10 cm, light penetrates the sample at a 90° angle. In generally

turbidity cannot be correlated to the weight concentration of suspended matter.

3.2.8.1 Materials
The materials used in turbidity measurements are:
Hach 2100A Turbiditmeter
Hach 50 ml tubes

Hach Stock Turbidity Suspension

3.2.8.2 Methodology
AWWA Standard Method 214 A, the Nephelometric Method for measuring
turbidity is the procedure used to analyze the clarity of the liquid dairy manure samples.
Calibrating the turbidity meter is the key to reproducible and accurate turbidity
measurements. Calibration is done by:
0 Preheating turbidity meters for 24 hours.
0 ' Creating a 400 NTU (Nephelometric Turbidity Units) standard solution by
combining as directed in Method 214A
0 Diluting 10 ml of the 400 NTU solution with 100 ml of deionized to produce a 40
NTU solution.
Note: all calibration and sample solutions are shaken well before turbidity testing
to assure that no settling has occurred.

0 Calibrating the turbidity meter in the 100 NTU range with the 40 NTU solution.

41

o Filling the 50 mL tubes with samples and placed in the turbidity meter for
analysis.
0 Calibration is continuous during analysis.

0 Reporting turbidity readings from 10 to 40 NTU’s to the nearest 1 NTU.

3.2.9 Temperature and pH Analysis
In addition to testing other characteristics, manure samples were also analyzed for

pH and temperature.

3.2.9.1 Materials
The meter used to measure temperature and pH is:

EXTECH pH/mV/I’emperature Meter

3.2.9.2 Methodology

The temperature and pH of the manure samples were measured prior to and
following the addition of a chemical coagulant in the laboratory tests. Pilot unit samples
were subject to pH measurements in the laboratory during the analysis for the other
characteristics listed in this chapter. Temperature was not measured on pilot unit

samples.

3.2.10 Manure Sampling

Manure samples for both laboratory and pilot unit tests were collected at Green

Meadow Farms in Elsie, Michigan. Figure 3.1, a manure system flow diagram for Green

42

Meadow Farms, gives an overall view of the system. The red star indicates the location

in the system where manure samples were drawn.

FIGURE 3.1 : Manure System Flow Diagram for Green Meadow Farms

 

 

 

Milking Center and Vet Barn Flush

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Liquid
- Storage
Cow Sand Manure
Alleys ‘ Manure ' Solids
Separation Separation
Solids
Storage

 

 

Manure scraped from the cow alleys is collected in reception pits located at the end of the
freestall barns. Manure from the reception pits is then metered into sand manure
separators. Screened flush water from the milking center and treatment barn serves as the
dilution water for the sand manure separators. Each freestall barn is equipped with a
reception pit and sand separator. Effluent from the sand separators is the pumped to a
rotating drum separator (Manure Solids Separation). The drum separator removes larger
solids from the manure stream. Effluent from the drum separator is stored in earthen
basins (liquid storage), while the solids are deposited onto a stacking/drying pad (solids

storage).

43

3.2.10.1 Materials
10 L Polypropylene container

50 ml Whirlpak

3.2.10.2 Methodology

Samples for analysis and treatment are collected from the effluent of the solid/liquid
separator before it reaches the earthen basins. A valve installed in the effluent pipe
allowed for sample collection. Laboratory samples were collected in a 10 L
polypropylene container and cooled for transport to the lab. All samples were
refrigerated (4 to 6°C) until use, manure samples were tested within 48 hours of
collection. The pilot system was stored in a building adjacent to the solids separator.
Manure for pilot tests was piped directly from the drum separator to the pilot unit. In
order to establish a daily phosphorus concentration, a separate individual sample was

collected in a Whirlpak. This individual sample served as the control and was analyzed

for TP, SP, rs, vs, COD, and pH.

3.2.11 Jar Test Procedure

Jar testing is a quick method for comparing the effectiveness of various
coagulants and flocculants for wastewater treatment. Laboratory jar tests should imitate
the actual mixing conditions in wastewater treatment plants. Variable speed jar tests can
simulate rapid mix chambers or flocculation basins. Gang stirrers allow different
chemicals or dosages to be compared in side by side tests which simulate the actual

mixing conditions anticipated in the field. Prior to testing, the wastewater was

44

characterized for pH and the target property for removal, in this case phosphorus. By
characterizing the wastewater, the type of coagulants or flocculants and their dosage

range can be narrowed to those which are known to work best on similar waste streams.

3.2.11.1 Materials
The equipment used in the jar tests was:
Phipps and Bird Jar Test Apparatus, 6 jar, variable speed
2000ml beakers
50ml Beakers

10 ml Pipette and Pipette Filler

3.2.11.2 Methodology
No standard for jar testing was found in published standards for wastewater.
However, the suppliers of coagulants and equipment have published basic guidelines for
jar tests that are accepted by the industry. The procedure used for jar testing followed
this routine:
0 1000 ml of well mixed dairy wastewater was measured into 6 - 2 liter beakers.
o 25 ml of sample was measured and set aside for later testing, this sample received
no treatment or mixing and served as the control sample.
0 The jar test apparatus was then turned on and the speed set to 100 rpm.
0 Samples were mixed for ten minutes prior to coagulant addition, during this time
pH was measured.

0 Chemical were added.

45

Following additions, mixing continued for a 5 minute period during which time
pH was again measured.

After mixing was completed the paddles were removed and the contents were
allowed to settle for a period of sixty minutes.

Three 10 ml samples were drawn from each jar using the pipette, the samples
were pulled from the liquid layer and deposited into the 50 ml beaker. Figure 3.2
presents the general settling pattern for the coagulated dairy manure during jar
tests. The sampling pattern occurred in a triangular pattern in the horizontal plane

similar to that shown in Figure 3.3.

FIGURE 3.2: Typical Settling Patterns for Jar

 

  

 

 

 

 

 

 

I :3323331:3f:§fi:ff:§f:§5232:3323} vI
3:33;; 53:23:33 v.
v. {:2}: 233:3: vs
£32353 .. Vs
:izi-I:.-..-:-fizz-1213;212:321: vs V
1 “-1 I
0 hr 1 hr 24 hr Floating

Mat

Liquid Dairy Manure D Liquid Fraction E3 Solid Fraction

After thorough mixing, a 2 ml sub-sample was drawn from the 30 ml sample; this
sub-sample was used in the 200 to 1 dilution for analysis.
Shortly after the sample was taken, the sludge and liquid height are measured

using a meter stick. The liquid-sludge line was determined by visual observation.

46

FIGURE 3.3: Jar Test Sampling Pattern, Top View

 

o The jar test beakers were then allowed to set for twenty-four hours at which time
they were sampled following steps 8 and 9. The sludge and liquid height was

again measured and recorded afier twenty-four hours.

3.2.12 Glassware Preparation

To assure accurate results glassware was cleaned prior to use. Generally, this
wais done by simply washing glassware with a non-phosphorus based detergent.
However, periodically washing glassware in a acid solution to remove film and residue
left by normal cleaning was necessary. Acid washing of glassware was essential to

remove residue and contaminants left from other laboratory projects.

3.2.12.1 Materials

To clean glassware the following was needed:

Polypropylene tub

47

3.2.12.2 Methodology

Continuous use of glassware can cause cross contamination and inaccurate results if
glassware is not regularly cleaned using an acid solution. Acid washing breaks down the
residue and film left on glassware by simple washing with soap and water. Acid washing
was carried out by soaking glassware in a 1N solution of Hydrochloric Acid followed by
a deinonized water rinse. This is the standard procedure accepted by the AWWA. After

rinsing, glassware was allowed to dry prior to use.

3.3 Pilot Unit
3.3.1 Pilot Tests

Pilot tests were conducted in a 100-gallon tank built from Plexiglas. Pilot testing
allowed the laboratory findings to be applied in actual field conditions on a much larger
scale. The pilot unit was not an actual scale up of the jar tests, though velocity gradients
and mixer clearances were maintained. Pilot tests were conducted at Green Meadow
Farms in Elsie, Michigan. The 100 gallon capacity of the pilot unit was approximately
1/1000th of the total daily manure stream of Green Meadow Farms.

The tank of the pilot unit was a two foot by two foot square box, four feet tall,
with 1/2” thick Plexiglas sidewalls. A square tank was selected over a round tank due to
cost. Five V2” National Pipe Thread (NPT) sampling ports were located down the side (a
second set was added in the field). The sampling ports were 1/2” ball valves with 1 1/2”
long nipples protruding into the tank. The nipples were installed to assure that samples
were drawn from the inner portion of the tank. A measuring tape attached to the tank

allowed for sludge height measurements.

48

A schematic of the mixing tank is shown in Figure 3.4. The tank and paddle were
built in the prototype laboratory shop in Farrall Hall. The mixing paddle is made of
stainless steel. The motor is mounted on a steel frame that sets on top of the tank, the
frame has legs which hook into the corners preventing the frame and motor from
twisting. The tank is top filled with liquid dairy manure, and emptied through a 2” ball
valve located near the bottom of the tank. Once assembled, the tank was filled with water

and the mixer speed was calibrated with a hand held tachometer.

FIGURE 3.4: Pilot Unit"

 

T Sampling Port
...... s ,

 

 

 

 

 

 

*not drawn to

3.3.1.1 Materials
The following is a list of materials used in pilot testing:
2’ * 2’ * 4’ Plexiglas tank and stand
1/2 Horsepower variable speed drive (Range 64 to 364 rpm)
Paddle, flat face, 5” * 14”, elevated 10” from the bottom
Polypropylene tub

Hose and scrub brush.

49

3.3.1.2 Methodology

The pilot unit tests were conducted in a similar fashion to the jar test described in an

earlier section. The process was as follows:

The mixing tank was filled with 100 gallons of effluent from the drum separator.
Control samples were drawn at the onset of filling and at the cessation of filling.
(The two samples were then mixed and sub-sampled. The sub-sample served as
the control.)

Premixing was initiated, premixing lasted for ten minutes at 100 rpm.

Chemical coagulants were added at the ten-minute mark.

Mixing at 100 rpm continued for 5 minutes after the chemical addition.
Following the cessation of mixing, settling began. (The timer was started as soon
as the mixer was shut off.)

Sludge settling was monitored by visually observing the height of the sludge line
at the measuring tape attached to the tank. (Sludge height measurements were
taken after 30 minutes, 1 hour, 24 hours, and 48 hours of settling.)

Manure samples were drawn from the five sampling ports at 1 hour, 24 hours, and
48 hours. ( Samples were collected in whirlpaks after allowing the sampling ports
to clear, approximately two seconds after opening the valve.)

Samples were transported to the Environmental Teaching Laboratory for analysis.
Pilot unit analysis was carried following the same procedures discussed for the jar

test.

50

CHAPTER 4

RESULTS AND DISCUSSION

4.1 General Comments

The results of characterizing the waste stream at Green Meadow Farms (GMF) are
imparted in Chapter 4. In addition, the findings from laboratory tests using various
chemical coagulants for phosphorus reduction in the liquid dairy manure are presented.
Testing of coagulants in the 100-gallon rapid mix chamber (the pilot test unit) is

discussed in the later portion of the chapter.

4.2 Manure Stream Characterization

The physical characteristics of dairy manure are influenced by numerous
variables, both environmental and physiological. Examples of factors include: 1) growth
or lactation stage of the animals, 2) manure age, 3) climatic conditions, 4) ration fed, 5)
bedding material, and 6) the manure handling system. A 640 kg (1400 lb) lactating dairy
cow will produce 67 kg (148 lb) of manure per day with a moisture content of 88% and a
density of 993 kg/m3 (62 lb/ft3) (MWPS, 2000). A further look at the composition of the
manure reveals that the total solids (TS) content of manure as excreted is 9.5% with a
volatile solids (VS) of 8.0%. The daily production of phosphorus in the manure as
excreted is 0.2 kg (0.42 lb) of P205. In addition, MWPS (2000) estimates manure lagoon
concentrations of P205 to be 19 lbs/1000 gal. It is important to remember that the
published book values can vary by as much as i30% from field measurements.

Liquid manure samples were collected over a 14 month period from various

points in the manure handling system at Green Meadow Farms. Following the

51

installation of a rotary drum separator in July of 2001, 33 manure samples were drawn at
approximately the same time of the day from the effluent of the separator for analysis.
The manure stream at Green Meadows is diluted by several different sources including:
1) the purging of the cattle waterer’s (dumping the contents of tip-tanks), 2) dilution
water added in the sand manure separation system, and 3) the cleaning of the floors of the
milking parlor, holding area, and special needs barn by flushing with fresh water. The
daily volumes of dilution water and manure produced by the 3,600 lactating cows housed
at GMF are presented in Table 4.1. The volumetric ratio of dilution water to manure is

approximately 1.7 to 1.

TABLE 4.1: GMF Manure Stream and Dilution Water Volumes for 3,600 Cows

 

Needs Barn 6
Flush2 18
Tank Waters2

35

otal Dilution Water 61
to Manure Ratio 1.7 to 1

MWPS-l8 (2000), Section 1, Table 6
2 Information provided by GMF

The 33 manure samples were analyzed for TS and VS on a wet basis as described in
Chapter 3, Method and Materials. Results and analyses of the liquid manure stream
characterization at GMF are listed in Table 4.2. For the 33 samples tested, TS averaged
2.79% with a standard deviation of 0.86%. Similarly, the liquid manure stream had an

average VS of 1.97% with a standard deviation of 0.44%. The TS and VS coefficients of

52

variance for the 33 samples were found to be 30.8% and 22.2%, respectively. This range

of variation is common for biological material like manure. Table A1, found in the

appendix, contains the raw data for the liquid manure stream characterization at GMF.

TABLE 4.2: Liquid Manure Stream Characterization Summary (n=33 from GMF)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Standard Coefficient I

Characteristic Mean Deviation Range Units of Variance I

Total Solids (TS) 2.85% 0.85% 1.33 - 5.02 % 29.97%]
Volatile Solids (VS) 2.00% 0.45% 1.05 - 3.00 % 22.46°/

COD 37,1541 10,013 14,700 - 53,600 m/L 26.95%]

[Soluble Phosphorus (SP) 196 36 108 - 278 mg / L 18.21°/d

ITotal Phosphorus (T P) 2,831 548' 1,780 - 3,745 mg / L 19.34%]

bH 8.47 0.27 7.84 - 8.89 3.19%]

 

Throughout the study, samples were split and a side-by-side analysis was run to

assure that laboratory testing procedures were accurate. Split samples analysis for TS

revealed a coefficient of variance (the ratio of the standard deviation to the mean) of

9.01%. The coefficient of variance for the VS analysis of the liquid dairy manure was

4.47%. Table 4.3 contains the results of the split sample analysis. TS and VS, like the

other parameters characterized, had relatively low coefficients of variance, generally less

than 10%. A coefficient of variance of 10% or less for a spilt analysis of manure is

considered an acceptable error attributed to sampling (Overcash et al., 1974).

TABLE 4.3: Split Sample Analysis and Average Coefficient of Variance

 

 

 

 

 

 

 

Standard Coefficient Average
Characteristic Mean Deviation of Variance C. V.‘
SP (ppm) 163 9 5.55% 6.59%
TP (ppm) 2620 122 4.66% 6.15%
COD (ppm) 39,500 11,078 28.04% 18.38%
TS (%) 2.44 0.22 9.01% 9.01%
VS (%) 1.95 0.09 4.47% 4.47%

 

 

 

 

 

 

 

The average coefficient of variance for multiple split samples.

53

The 33 liquid manure stream samples were also tested for SP, TP, COD, and pH as
discussed in Chapter 3. The samples were found to have an average SP of 196 mg/L with
a standard deviation of 36 mg/L. The overall variance of the 33 samples was 18%. The
mean TP of the liquid dairy manure was 2,831 mg/L with a standard deviation of 548
mg/L. TP varied by 19% for the 33 samples.

Again, the split samples were tested simultaneously to check for errors in laboratory
procedures and testing accuracy. The coefficients of variance for SP and TP were 6.59%
and 6.15%, respectfirlly. Overcash et al. (1974) reported that a coefficient of variance of
10% is typical for total phosphorus measurements in the same phosphorus range as this
study.

COD analysis of the manure samples found a mean of 37,154 mg/L with a standard
deviation of 10,013 mg/L. Split sample testing found a coefficient of variance of 18.3 8%
for COD, the highest coefficient of variance for all the parameters evaluated. pH
averaged 8.47 with a range of 7.84 to 8.89.

Preliminary data revealed that turbidity measurements provided little insight into
predicting phosphorus or solids removal. One issue that made turbidity measurements
difficult is the sensitivity of the turbidity machine. Calibration is an ongoing process
while measurements are taking place. In addition, moisture and dust accumulation on the
bulb caused difficulties with maintaining a consistent source of light. Furthermore, the
dilution rate used for phosphorus analysis did not produce significant differences in
turbidity measurements. The range used for turbidity measurements was 0 to 100
Nephelometric Turbidity Units (NTU). The range of turbidity measurements for

untreated samples was 17 to 28 NTU, while the range of turbidity for various treated

54

samples was 15 to 30 NTU. This being understood, turbidity analysis was not continued

beyond the preliminary tests.

4.3 Laboratory Testing of Coagulants and Liquid Dairy Manure

Laboratory tests were conducted using several chemical coagulants to evaluate
their usefulness in reducing phosphorus concentrations in the liquid fraction of the dairy
manure stream from GMF. The chemicals used to treat the dairy manure included
hydrated lime, 40% Alum solution, and 40% Ferric Chloride. Laboratory analyses were
conducted using a six slot jar test apparatus and followed the jar test procedure outlined
in Chapter 3. Samples were collected after 1 and 24 hours of settling from the liquid
layer. Figures 3.2 and 3.3 show the sampling points for the jar tests. The liquid layer
was determined by visual observation and generally occupied the upper portion of the
beaker. The liquid dairy manure was collected from GMF as discussed in Chapter 3 and
transported to the lab for same day testing.

The goal of the lab tests was to reduce SP and TP in the effluent (liquid layer) by
80% using chemical additions. The level of phosphorus concentration reduction desired
will be farm specific, depending on several factors including land base, soil phosphorus
test levels, field distance from livestock, compost market, fertilizer prices, and livestock
management goals. With this in mind, treatments were set up to demonstrate that effluent
phosphorus concentration can be managed to meet the needs of the dairy operation.

The phosphorus reductions discussed in this chapter are strictly reductions of the
phosphorus concentration in the liquid fraction (the upper portion of the jars) and

concentrations of phosphorus in the sludge. Phosphorus was not removed from the

55

system, only transformed and concentrated. Through further processing with readily
available technology, the phosphorus-rich sludge could have been removed. Processing

options to recover the sludge include filter bags, filter presses, clarifiers, and centrifuges.

4.3.1 Settling with No Chemical Addition

Each set of jar test experiments included a control jar. The control jar received no
treatment other than mixing. The control jar was subjected to the same mixing conditions
as the treatment jars. SP and TP were measured in the liquid layer 60 minutes and 24
hours after the cessation of mixing. The liquid layer was determined by visual
observation. Each experiment with a chemical coagulant also had a control jar, Table 4.4
presents the average phosphorus reduction in the control jar for each coagulant tested
(lime, alum, and ferric chloride). Additionally, Table 4.4 contains the average reduction
of SP and TP and their standard deviations for all control jars. Overall, the SP and TP in
liquid fraction of the control jar was reduced by 22.82% and 24.03%, respectively, after 1
hour of settling. At 24 hours of settling, SP and TP reductions in the liquid portion
increased to 71.5% and 60.0%, respectively. All the results had a standard deviation of

less than 5.10%.

TABLE 4.4: Control Jar — Phosphorus Reduction

 

 

 

 

 

 

 

 

 

 

Phosphorus Reduction (%)
Experiments 1 Hour 24 Hour
SP TP SP TP
Lime 23.92 29.74 73.53 57.92
Alum 17.28 20.53 70.79 65.50
Ferric 27.26 21 .82 70.23 56.51
Average: 22.82% 24.03% 71.52% 59.97%
tandard Deviation: 5.08% 4.98% 1.77% 4.83%

 

 

 

 

56

 

The natural settling that occurs appears to be Type 3 or zone settling because the
mass of manure solids and nutrients (phosphorus) settle as a unit. The settling types are
defined in Chapter 2. The agitation of the contents of the control jar may enhance the
normal settling process by utilizing natural polymers in the dairy manure as flocculating
agents. Similar to flocculation using synthetic polymers, the natural polymers may
bridge phosphorus ions, trapping and precipitating the phosphorus when agitation ceases.
The unaided settling of phosphorus after 1 hour in this trial is less than reported in other
studies discussed in the literature review. However, the phosphorus reductions for 24

hours agree with results reported in Chapter 2.

4.3.2 Lime Additions

Lime, in the form of a 5% lime solution, was added to the liquid dairy manure for
the purpose of phosphorus coagulation. Table 4.5 contains the mean results found in jar
test experiments where lime was added as the coagulant. Five treatments levels - 1.32,
2.64, 3.97, 5.29, and 6.61 g of lime/L wastewater - were selected for testing based on
earlier experiments. Estimated chemical costs for the five treatments are $0.50, $1.00,
$1.50, $2.00, and $2.50 / 1000 gal of liquid dairy manure from GMF, respectively. The
chemical costs are based on the December 2000 issue of the Chemical Market Reporter in
which hydrated lime is listed at $70/ton.

Coagulating of phosphorus in the liquid manure stream with lime proved to be a
USCfiJI method for reducing the phosphorus concentration in the liquid portion. SP
concentration reductions in the liquid fraction ranged from 30 to 79% after 1 hour of

settling. Similarly, 1 hour of settling reduced the concentration of TP in the liquid

57

TABLE 4.5 Phosphorus Concentration Reduction Using Lime

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Treatment Phosphorus Reduction (%)
‘ Dosage Cost 1 Hour 24 Hour
_(g/L) ($l1000 gal) SP TP SP TP
0.00 0.00 23.92 29.74 73.53 57.92
1.32 0.50 39.18 42.43 77.91 69.92
2.64 1 .00 40.49 39.43 82.04 66.76
3.97 1.50 62.04 53.17 82.49 67.50
5.29 2.00 77.80 62.67 83.75 74.17
6.61 2.50 78.70 67.90 81.70 66.90

 

 

fraction by 42 to 68%. One hour of settling in the control jar decreased the SP and TP
concentrations by 24% and 30%, respectively. Lime as a coagulant increased the
minimum SP reduction by 6% and the minimum TP reduction by 12% over that achieved
in the control jar, for all treatment levels. Figure 4.1 presents the average phosphorus
reduction versus the lime treatment dose. Table A2 in the appendix, contains the raw
data for the laboratory jar tests using lime as the coagulant. Allowing settling to continue
for 24 hours improved both SP and TP reductions markedly in the lower doses (1.32,
2.64, and 3.97 g/L). The highest lime doses (5.29 and 6.61 g/L) saw much smaller
increases in the phosphorus reduction. A slight reduction in the efficiency from 1 hour to
24 hours for the TP was seen at the 6.61 g/L dose.

The lime dose that most closely meets the goal set for the laboratory tests was
determined to be 5.29 g/L. This level of treatment achieved an average decrease in SP of
78% and TP of 63% after 60 minutes of settling. At 24 hours of settling, SP and TP were
reduced in the liquid fraction by 84% and 74%, respectively. The range of the standard
deviation for the results from the 5.29 g/L treatment was 2.2 to 5.5% with an average
deviation of 3.8%. The next higher lime dose (6.61 g/L) produced only marginal

increases in phosphorus reductions with no change in the standard deviation. Lower

58

FIGURE 4.1: Average Phosphorus Concentration Reduction
Using Lime as the Coagulant, Lab Tests

100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00

0.00
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

Treatment Level (gIL)

Phosphorus Reduction (16)

 

 

{—o— Soluble_1 hr --l——Total_1 hr - - e - -Soluble_24 hr - - I - -Total_24 hr]

 

FIGURE 4.2: Lime Treatment Costs Vs Phosphorus Reduction
Lab Tests

100.00
90.00
80.00
70.00 ”0".......-~ '

-.-.--..-- --.""-.. --------

Phosphorus Reduction (%)
8
8

 

0.00 0.50 1.00 1.50 2.00 2.50 3.00
Treatrrrent Costs ($11000 gal)

 

[+Soubre_1 hr --—I---Total_1 hr - - o - -So|uble_24 hr - - I - -Total_24 hr]

 

treatment levels were much less predictable and had a much larger deviation from the

mean. Treating the liquid dairy manure from GMF for the desired phosphorus reduction

59

using lime would cost approximately $2.00 per 1000 gallons of liquid dairy manure.
Figure 4.2 is a graph of the chemical (lime) cost versus the percent reduction in
phosphorus in the liquid fraction.

The benefits of using lime as a coagulant over settling alone to separate
phosphorus include increased removal rates after 1 hour and 24 hours. Additionally, the
sludge formed from the calcium phosphorus and manure solids appears to be more stable
than the nutrient-rich sludge produced by natural settling. The addition of lime as a
coagulant did not increase the volume of sludge produced. Naturally settled sludge and
sludge coagulated with lime occupied approximately one third of the volume of the 1000
mL sample, the other two thirds of the volume was occupied by the liquid fraction. If the
stability is actually increased, further processing options that cannot be used on a less

stable sludge become available.

4.3.3 Alum Additions

Alum, as a 40% solution in water, was also used as a coagulant for phosphorus
removal. The alum was purchased as a solution from Chemco Products Inc. in Howell,
Michigan. The dosages of alum used were 0.8, 2.0, 4.0, 6.0, and 8.0 g/L of liquid dairy
manrue. A summary of the experimental results is contained in Table 4.6. The chemical
cost of alum for the respective treatments is $2.12, $5.29, $10.58, $15.88, and $21.17 per
1000 gallons of liquid manure from GMF. The treatments costs are based on an
aluminum sulfate price of $281 per ton (Chemical Market Reporter, 2000). Table A3 in
the appendix, contains the raw data from the laboratory experiments where alum was

used as the coagulant.

60

 

TABLE 4.6: Phosphorus Concentration Reduction Using_Alum

 

 

 

 

 

 

 

 

 

 

 

 

Treatment Phoghorus Reduction (%)
Dosage Cost 1 Hour 24 Hour
49A.) ($/1000 gal) SP TP SP TP
0.00 0.00 31.96 40.64 66.28 66.80
0.80 1.41 41.45 16.47 79.74 75.50
2.00 3.53 72.58 38.27 88.91 85.40
4.00 7.06 92.75 48.16 103.80 89.70
6.00 10.58 95.57 69.98 104.31 88.02
8.00 14.11 101.80 82.29 107.74 100.79

 

 

 

 

Alum proved to be extremely useful in coagulating and settling phosphorus under
laboratory conditions. The range of SP decrease in the effluent was 41 to 100% after 1
hour of settling. During that same period, the TP concentration was reduced in the liquid
by 16 to 82% for the various treatment levels. After 24 hours of settling, the minimal SP
concentration reduction increased to 80% and the range of TP reductions was 76 to
100%. The control jar produced a decrease in the concentration of SP by 32% and TP by
40% after 60 minutes of settling. A more detailed summary of the results for phosphorus
reduction using alum as the coagulant can be seen in Table 4.6.

The reductions in TP for the two treatment levels of 0.8 and 2.0 g/L after 1 hour of
settling were actually lower than for the control jar. This can be attributed to incomplete
flocculation due to an insufficient dose of alum. Flocculation was observed in the jars for
both treatments, but the size of the coagulated particles was observed to be smaller than
for the three higher doses (4.0, 6.0, and 8.0 g/L). Smaller particles translate into lower
molecular weight of the individual particles, hence the slower settling with some alum

treatments.

61

Unlike with lime, the determination of the desired dose is much more difficult with
alum. The 8 g/L dose achieved the set goal of 80% reductions in the concentrations of
both SP and TP in the liquid fractions, after only one hour of settling. The standard
deviation for this treatment level is 21%, much higher then the standard deviation for the
lime treatments. However, the average deviation for all alum treatments is 22%. The
problem with this level of alum treatment (8 g/L) is the cost, 8 g/L of alum is estimated to
cost $14.11 per 1000 gallons of liquid manure. If settling were to continue for 24 hours,
the 4 g/L treatment level achieved a 100% reduction in SP and a 90% decrease in TP,
well above the goal of 80% phosphorus reduction. The standard deviation for the 4 g/L
treatment level was 22%, this standard deviation is nearly identical to that of the 8 g/L
dose of alum. The chemical cost for 4 g/L of alum is $7.06 per 1000 gal of liquid dairy
manure, half the cost of the 8 g/L dose. The percent reduction in the phosphorus
concentration versus the treatment dose and cost is displayed in Figures 4.3 and 4.4.

The floc produced using alum was a visibly larger aggregate than produced by the
lime addition. The sludge production in the alum treated jars occupied approximately
50% of the total manure volume. The other 50% was occupied by the liquid fraction
(Figure 3.2). The increased volume of the sludge is attributed to the dissolved
particulates that react with the alum to form the floc. The flocs are large “fluffy”
molecules that contain both dissolved and suspended particulate. Compression settling
did not occur in the 24 hour settling period. In some instances, the solid fraction formed

a floating mat of sludge rather than a settled sludge.

62

FIGURE 4.3: Average Phosphorus Concentration Reduction
Using Alum as the Coagulant, Lab Test

100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00

0.00

0.00 1 .00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00
Treatment Level (gIL)

L—O— Soluble_1 hr +Total_1 hr - - O - -Soluble_24 hr - - 'I - -Total_24 hr

Phosphorus Reduction (%)

 

 

 

FIGURE 4.4: Alum Treatment Cost Vs Average Phosphorus Reduction
Lab Tests

100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00

0.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00

Treatment Cost ($11000 gal)

Phosphorus Reduction (%)

 

 

+Soluble_1 hr --I---Total_1 hr - - O - -SolubIe_24 hr - - I - -Total_24 hr

 

63

4.3.4 Ferric Chloride Additions

The last of the chemical coagulants tested in the laboratory was ferric chloride
(FeClg). A 40% solution of ferric chloride purchased from Chemco Products Inc., was
used in both laboratory and pilot unit tests. The FeC13 treatment levels selected for
testing were 0.8, 2.0, 4.0, 6.0, and 8.0 g/L. Estimated treatment costs ($/1000 gal of
liquid dairy manure) for the respective treatments are $2.42, $6.05, $12.10, $18.14, and
$24.19. The chemical costs are based on purchasing FeCl3 in bulk at $315/ton. A
summary of the average concentration reductions of SP and TP for the various treatment
levels of FeC13 is found in Table 4.7. Table A3 in the appendix contains the raw

experimental data from laboratory tests using FeCl3 as the coagulant.

TABLE 4.7 Phosphorus Concentration Reduction Using_FeCl3

 

 

 

 

 

 

 

 

 

Treatment Phosphorus Reduction (%)
Dosage Cost 1 Hour 24 Hour
FJg/L) (5/1000 gal) SP TP SP TP
0.00 0.00 27.26 21.82 70.23 56.51
0.80 2.42 42.54 32.60 78.72 56.45
2.00 6.05 52.68 25.23 79.13 56.79
4.00 12.10 65.55 31.89 81.32 62.31
6.00 18.14 101.82 65.93 99.03 76.25
8.00 24.19 104.51 73.92 103.77 82.52

 

 

 

 

 

 

 

 

Using FeC13 as a phosphorus coagulant produced mixed results in the laboratory.
The goals of 80% reduction in SP and TP were achieved by two treatments, 6 and 8 g/L,
after 1 hour of settling. The 4 g/L dose after 24 hours of settling produced a decrease in
SP of 81%, slightly above the goal. All treatment levels showed an increase in the
reduction of SP when compared to the control jar results. The SP concentration in the

liquid fraction of the control was reduced by 27% after 60 minutes of settling, while the

64

range for SP reduction using various treatment levels of Fer was 43% to 100%.
Likewise, TP reductions benefited from the addition of FeCl3, the TP of the control was
decreased by 22% after 1 hour of settling. The 1 hour settling range for TP reductions
with FeCl3 was 25% to 74%. Figure 4.5 presents a graphic view of the treatment level
versus the percent reduction in the phosphorus concentration of the liquid fraction.

Allowing the settling to continue for 24 hours produced very different results
from those recorded after only 1 hour of settling. The range for SP reductions after 24
hours was 79 to 100% with the control reduction at 70%. The TP reduction range for 24
hours was 56 to 83%, the control jar produced a reduction in TP of 57%. The three low
doses of FeC13 (0.8, 2, and 4 g/L), in addition to the control, showed almost identical
results in TP reduction. The 8 g/L treatment level achieved the goals of 80% reductions
in both SP and TP after 24 hours. However, the 6 g/L dose of FeCl;; appears to be the
optimum treatment level for ferric chloride. After 24 hours of settling, the liquid fraction
SP level was decreased by 99% with the TP level dropping by 76%. The 8 g/L treatment
produced identical SP results with an increased reduction of 6% for TP. Increasing from
6 g/L to 8 g/L increases chemical costs by $6.05 per 1000 gal of liquid dairy manure.
The increase in chemical dosage translates into a daily increase of $605 if a dairy were
treating 100,000 gallons of liquid dairy manure. Figure 4.6 presents the chemical cost
versus the phosphorus reduction for ferric chloride.

Liquid dairy manure treated with ferric chloride did not produce the distinct
liquid-solid interface experienced as with other chemical coagulants. The low pH of the

Fer and the buffering capacity of the dairy manure caused a reaction resulting in a large

65

FIGURE 4.5: Average Phosphorus Concentration Reduction
Using FeCI; as the Coagulant, Lab Tests

1 00.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00

0.00
0.00 1 .00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00

Treatment Level (gIL)

Phosphorus Reduction (16)

 

 

—O—Soluble_1 hr +Total_1 hr - Q - Soluble_24 hr - - I - -Total_1 hr

 

FIGURE 4.6: FeCI5 Treatment Costs Vs Phosphorus Reduction
Lab Tests

100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00

0.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00

Treatment Costs ($11000 gal)

Phosphorus Reduction ()6)

 

 

—O-—-Soluble_1 hr ~I--Total_1 hr - - O - -So|uble_24 hr . . I - vTotal_24 hr

 

66

release of CO2. This reaction occurred in the treatment levels 4, 6, and 8 g/L. The

release of C02 caused a floating mat to form. The floating mat contained the sludge that

would normally be expected to settle. Distinct settling seldom occurred when FeC13 was

used as the coagulant. The two low level treatments (0.8 and 2 g/L) resulted in good

flocculation with very little settling, but no foam formation. In the cases of foam

formation, sampling was difficult because settling did not occur. On the highest

treatment levels (6 and 8 g/L) small pockets of free water were mixed into the foam or

located at the bottom of the jar.

4.3.5 Chemical Treatment Cost Analysis

Table 4.8 summarizes the treatment levels for the various coagulants which best

met the goals of 80% reduction in SP and TP. Not all coagulants achieved the goal of

80% reductions of SP and TP in the liquid fi'action. The last column of Table 4.8 shows

the daily treatment costs for the selected treatment level of the three coagulants.

Equipment costs are not accounted for in the values.

TABLE 4.8: Chemical Doses for Desired Reduction in Phosphorus Concentration

 

 

 

 

 

 

 

 

 

 

| Chemical Phosphorus Reduction (%) GMF
| Dosage Costs 1 Hour 24 Hour Daily
I Jg/L) ($/1000 gal SP TP SP TP Costs“
|5% Lime Solution 5.29 $2.00 78 63 84 74 $239.73
|40% Alum Solution 4.00 $7.06 93 48 100 90 $846.72
I407. FeCI3 Solution 6.00 $18.14 100 66 99 76 $2,177.28

 

 

 

 

‘Assuming 120,000 gal/d of liquid dairy manure

Table 4.9 presents market values for the two most common phosphate fertilizers

used in agriculture. Triple superphosphate (TSP) and Diammonium phosphate (DAP)

contain 45% and 46% actual P205 and have an average cost of $138 and $148 per ton

67

 

respectively (Fertilizer Market Bulletin, 2000). The actual cost per pound of phosphorus

in TSP and DAP is $0.35 and $0.37, respectively.

TABLE 4.9: Common Phosphate Fertilizers and Prices

 

 

 

 

 

 

 

 

 

Fertilizer Type P205 Actual P205 Actual P Price‘ Price

(%) (I Man) (I b/ton) ($lto n) ($l lb of P)
Triple Superphosphate 45 900 444 $137.50 $0.35
Diammonium Phosphate 46 920 453 $148.00 $0.37

 

 

 

‘Fertilizer Market Bulletin, 2000

Table 4.10 presents the value of the phosphorus concentrated in the sludge from
the liquid dairy manure stream. The value of the TP recovered is based on the
assumption that elemental phosphorus has a value of $0.35 per pound and the average
daily concentration of TP in the liquid manure stream is 2,734 mg/L. Infrastructure and

labor costs are not taken into account in this cost analysis.

TABLE 4.10: Comparison of Chemical Costs Vs Value of TP Recovered

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Settle Treatment TP Value of
Time Treatment Dosagg Costs Concentrated’ Recovered TP2
(hr) (g/L) ($ld) (lb/d) (SM)
1 5% Lime Solution 5.29 $239.73 1,716 $600.60
1 40% Alum Solution 4.00 $846.72 1,319 $461.50
1 40% Fer Solution 6.00 $2,177.28 1,805 $631.81
24 5% Lime Solution 5.29 $239.73 2,031 $710.78
24 40% Alum Solution 4.00 $846.72 2,456 $859.56
24 40% FeCl3 Solution 6.00 $2,177.28 2,088 $730.71

 

 

 

 

‘Assumes 120,000 gal/d of liquid manure
lCalculated using phosphorus reductions found in laboratory tests multiplied by average TP in the manure stream
2Assumes that phosphorus reductions in effluent can be recovered in the sludge

The data presented in Table 4.10 makes it clear that, if the assumptions are

correct, phosphorus removal via chemical additions is a viable option for liquid dairy

68

manure. Treating 120,000 gal/d of liquid dairy manure with lime could concentrate 1,716
lb/d of phosphorus in the sludge after 1 hour with a fertilizer value of $600. The daily
chemical cost for the 5.29 g/L of lime is $240. This yields a potential profit of $360.
From Table 4.10, it is apparent that alum and ferric chloride are not economically viable
after 1 hour settling period. However, after 24 hours of settling, the fertilizer value of the
phosphorus reduction is $860 with a treatment cost of $847. This implies that, after 24
hours of settling with a treatment of 4 g/L of alum, enough phosphorus would be
contained in the sludge to yield a $13 profit. Additionally, alum eliminated 100% of the
SP in the liquid fraction after 24 hours of settling, lime reduced the SP concentration by
84% in the effluent. After 24 hours settling, the chemical cost of ferric chloride versus
the value of the recovered phosphorus proved uneconomical for treating this type of
liquid dairy manure. In line with the goals of the project, alum and lime are the
recommended chemical treatment options for reducing the phosphorus concentration in

the liquid manure stream.

4.4 Pilot Unit Results

In the fall of 2001, a pilot unit was constructed. A schematic diagram is found in
Chapter 3, Figure 3.4. The pilot unit has a capacity of 100 gallons. The pilot unit was
designed to mimic the jar test apparatus. The velocity gradient and mixing regime were
maintained. However, the pilot unit is a rectangular chamber, while the jar tests were
completed in circular beakers. The rectangular design was selected due to construction

costs and practicality of future scale-ups. The pilot unit, in addition, was equipped with

69

five sampling ports spaced vertically to allow for profile sampling. A second set of

sampling ports was installed later to allow for horizontal profile sampling.

4.4.1 Velocity Gradient Calculations

The velocity gradient (G) or mixing intensity is a critical element in wastewater
coagulation. The G—value is a function of the mixer power (W), chamber volume (m3),
and the absolute viscosity (N °s-m‘2). The velocity gradient is calculated using Equation
2.1. As discussed in Chapter 2, Sievers (1989) found the optimum velocity gradient for
liquid dairy manure coagulation with iron to be 22.3 s'l. The G-values achieved in the jar
test were found to be approximately 50 8", based on Figure 4.7, which contains G-
Curves supplied by the Phipps and Bird Company. The curves in Figure 4.7 were created
using water. The mixing apparatus for the pilot unit was designed based on the optimum
value for the velocity gradient from the literature (22.3 s") and the actual velocity
gradient achieved in lab tests (determined to be 50 s'1 from Figure 4.7). The calculated
G-value for the pilot unit using Equation 2.1 is 33.77 S”, assuming that manure has a

dynamic viscosity sirrrilar to water.

4.4.2 Pilot Unit Tests

The pilot unit tests focused primarily on coagulation with lime as a coagulant
with alum and ferric chloride used to a lesser extent. Each pilot test was conducted over
a 48 hour period. The procedure was to fill and chemically treat the tank of liquid dairy
on the morning of day one. Operating procedures for the pilot unit are found in Chapter

3. The first samples were drawn after 1 hour settling. Samples were then collected on

70

the next 2 consecutive mornings at approximately the same time. Sample analysis was
completed in the afternoon of collection. Pilot unit tests were completed during the fall
of 2001 and the winter of 2002. The goal of the pilot unit tests was to compare

laboratory findings with a larger scale treatment operation under actual field conditions.

FIGURE 4.7: G Curves for Phipps and Bird Jar Test Apparatus
See Michigan State University, Department of Agricultural Engineering Library

71

4.4.2.1 Pilot Unit Sampling

As discussed in Chapter 3, the pilot unit was equipped with 5 primary sampling
ports oriented in the vertical plane. A secondary set of sampling ports was installed on
the adjacent face (at a 90° angle to the primary set) to test the uniformity of the horizontal
plane. The full data set used for analyzing the uniformity of the horizontal plane is
located in Table A5 in the appendix. Table 4.11 presents a condensed summary of the

results.

Table 4.11: Horizontal Plane Differences in the Pilot Unit*

 

 

 

 

 

 

 

 

 

 

 

 

Mean Standard Deviation Coefficient of Variance

Depth SP TP SP TP SP TP

(cm) (m9/_L2_ (mg/3 (mm ML) (%) (%)
96.5 208 2,525 5 91 2.54% 3.59%
76 208 2,657 7 233 3.39% 8.78%
58.5 205 2,342 2 212 1.20% 9.04%
30.5 213 2,589 8 251 3.64% 9.68%
7.5 217 2,275 3 393 1.46% 17.28%
Averagesl 210 2,478 5 236 2.45% 9.68%

 

 

 

 

 

 

 

*Standard deviation and coefficient of variance for mean values of SP and TP

at various depths in the pilot unit.

The concentration of SP varied little from one horizontal plane to another. TP
concentrations showed a slight increase in variation with tank depth. The deepest ports,
located 3 inches off the floor of the tank, had the largest standard deviation for TP at 393
mg/L. Sampling and lab error can sighted for differences in the standard deviation. The
results of sampling the horizontal plane show clearly that liquid manure in the plane is

uniform and that one set of sampling ports was sufficient for firrther experiments.

72

4.4.2.2 Phosphorus Reduction without Chemical Addition

Several experiments were carried out to characterize the reduction of the
phosphorus concentration in the liquid fraction with no chemical treatment. The
experiments with no chemical additions are broken into two categories, mixing and no-
mixing. The mixing experiments utilized the same mixing schedule as if a chemical
coagulant were being added, the procedure is described in Chapter 3. The no-mixing
experiments involved simply filling the chamber with effluent from the solid separator
(liquid dairy manure) followed by undisturbed settling.

Phosphorus settling with no mixing produced similar results to those observed in
the laboratory tests. Figures 4.8 and 4.9 present the average reductions in the
concentrations of SP and TP in the pilot unit with no mixing. The raw data for the no-
mixing and mixing experiments are found in Table A6 in the appendix. Figures 4.8 and
4.9 demonstrate that both SP and TP are reduced in the upper two sampling ports after 24
hours. Allowing settling to continue to 48 hours further reduced the TP concentration in
ports 1 and 2, the concentration of SP did not change. Additionally, the sludge layer
(solids fraction) occupied 55% of the chamber volume after 48 hours. As discussed
earlier, the settling that is observed is believed to be of the type 3 nature or hindered
settling.

The data set used to create Figures 4.8 and 4.9 is presented again in Figures 4.10
and 4.11. The axis orientation in Figures 4.10 and 4.11 is such that the sampling height is
presented on the x axis and the percent phosphorus reduction is presented on the y axis.
The bold lines running perpendicular to the x axis represent the liquid/solid interface

depth at the sampling time (the line color and dash spacing corresponds with the legend).

73

The bold lines running perpendicular to the x axis represent the liquid/solid interface

depth at the sampling time (the line color and dash spacing corresponds with the legend).

FIGURE 4.8: SP Reductions with No Mixing or
Chemical Treatment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

450

400
$350 ._ ___________ -- -X Sampling

300 44”]? Port#
g /‘-’ '"w’mvun‘fi ___._ 1
:3 250 _.—" wwflefifi‘M'mflwn
u .":wlw~,waww* —.—2
EMKMHF-‘W‘QWL _.*..3
0150 --...___fl_ ““fiw‘d
a \ —"—5

so :’

O ‘I' I I U I
0 10 20 30 40 50 60
Time(hr)

FIGURE 4.9: TP Reductions with No Mixing or Chemical Treatment

 

 

 

 

 

 

  
   
       

 

 

 

 

 

 

 

 

 

7000

6000
.. Sampling
E5000 Portft
.. —e—1

4000 ___...

__.._.._.._.......& ........... —X _._2

aooo .«:.~;.~.:r.:-_.......... ............. ".1212": s --*--3
5 “cu-...- “““““““““““ - .... $2....4
E2000 —-iii-5

1000

0 l T I l V
0 10 20 30 40 50 60

74

FIGURE 4.10: Pilot Unlt SP Reduction (or Concentratlon) with No Treatment

Liquid/Solid
Interface

_1hr

-— 824T"
.. .. 48hr

 

Sample Height (cm)
(measured from bottom)

 

[—e—1hr --¢-24hr--¢o--48hr]

 

FIGURE 4.11: Pilot Unlt TP Reduction (or Concentration) with No Treatment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

800096 I
I I Liquid/Solid
600096 Interface
10. I —1h|'
340.00% J — - 24 hr
g ‘e'. I “ ~ 48 hr
8200091. \‘u. 5
n: ‘s\ k“ I
0 N 7!.
0.00% li‘ 1
T.“ “'"‘ .... \
"he '“w...
20.00% - ‘-~. Ate
f r “~ .I'
40.00% I L
l "
80.00% it 1* 1. ttf 5.
4O 35 3O 25 20 15 10 5 0
Sample Height (cm)

(measured from bottom)
—e—1hr—-I- 24hr--*--48hr]

 

 

75

For the sample taken at 48 hours, Figures 4.10 and 4.11 show that the liquid/solid
interface corresponds with the change from phosphorus reduction to phosphorus
concentration.

Figures 4.12 and 4.13 show the average SP and TP concentration reductions for
the second experiment with no chemical coagulant. In this experiment, the pilot unit
contents were mixed in the same manner as if a coagulant were to be added, however no
chemical coagulant was added. In comparison with the no mixing results, it appears that
mixing enhances separation by increasing the phosphorus concentration reduction depth
and decreasing the volume of the sludge. Table A6 in the appendix contains the raw data
used to generate Figures 4.12 and 4.13. Similar to the control jar, mixing may enhance
phosphorus adsorption to the naturally occurring polymers excreted in the feces. The
larger particles created by the adsorption are denser, thus settling is improved.

Figures 4.12 and 4.13 are created from the same data set as Figures 4.14 and 4.15.
A described previously, the figures have different axis configurations. The bold lines
rising fiom the x axis represent the depth of the liquid/solid interface. Samples collected
after 24 and 48 hours with the mixing only treatment show a distinct pattern at the
liquid/solid interface. Both SP and TP reductions switch to concentrations near the
interface. The liquid/solid interface generally moved the most (settling) in the first 24

hours after undisturbed settling began.

76

FIGURE 4.12: SP Reductions with Mixing, but No Chemical Coagulant

 

-.-—v‘—"""""x

 

u¥“‘“_

 

 

 

 

 

 

 

 

 

SPConcentratioMmg/L)
8888888888

 

 

 

FIGURE 4.13: TP Reductions with Mixing, but No Chemical Addition

5

m m m m
mmmn

 

 

 

Sampling
Port #

 

—+—4
~l~2
”ens
mew4
~a-s

 

 

 

Sampling
Port #

 

 

 

 

 

TP Concentration (mg/I.)

 

~l~2
wens
mem4
~w-5

 

 

 

 

.§§§§§§

 

 

 

 

O

10

20 30 40 50
Time (hr)

77

FIGURE 4.14: Pllot Unit SP Reduction (or Concentration) wIth only Mixing

 

100.00%
80.00% Liquid/Solid
Interface
"’ 40.00% m ° 24 hr
3 — — 48 hr
§ 20.00%
E 0.00%
M
g. -20.00%
6 40.00%
E
-60.00%
-80.00%
400.00%
40 35 30 2Sample Height (cm) 10 5
(measured from bottom)

 

[+1 hr +24 hr +48 hr]

 

FIGURE 4.15: Pilot Unit TP Reductions (or Concentrations) with only Mixing

 

80.00%
Liquid/Solid
6000* Interface
_1 hr
g 40°09" __ .24 hr
our ee- 48 I"
g 20.00%
a: 0.00%
320.00%
‘L 40.00%
-60.00%
I
80.00%

(measured from bottom)

 

F—e—ihr-a- 24hr--*--48hr|

 

78

4.4.2.3 Chemical Coagulation with Lime Additions

Coagulation using lime was the primary focus of the pilot unit tests. Similar to
laboratory analysis, five treatment levels were used in the field tests. The five lime
treatment levels tested in the pilot unit were 0.66, 1.32, 2.64, 3.96, and 5.28 g/L. Table
4.12 contains the averaged phosphorus reductions at sampling port 2 in the pilot unit for
each of the lime treatment levels. The highest treatment level for the pilot test coincides
with the laboratory treatment level that produced results closest to the project objective.
Figures 4.16 and 4.17 present the SP and TP concentration reductions using 5.28 g/L of
lime at each sampling port with respect to time. The phosphorus concentrations (SP and
TP) were significantly reduced in sampling port 1 after 24 hours. After 48 hours, the SP
and TP concentrations in the effluent drawn from ports 1 and 2 were reduced by 66% of
the initial sample. The effluent sampled from port (5) saw a sharp increase in SP and TP
concentrations fi'om 1 to 24 hours of settling. Phosphorus concentrations in the slurry
sampled from port 5 did not change significantly from 24 to 48 hours.

Table 4.12: A Reduction at Port 2 in the Pilot Unit

Treatment 1 Hour 24 Hour 48 Hour
Location Soluble Total Soluble Total Soluble Total

       

79

SP Concentration (mgIL)

FIGURE 4.18: SP Reductions with 5.28 9". of LIme as the Chemical Coagulant

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

450
400 Sampling
350 .___.___ Porrrr
...--*""'“ '“"-------il<
3w r"w’ +1
50 "t’. “.“2
I
'0" “*“3
200
NM» 2......“qu “*7“
| N‘Gfi::fi~~m~ nnnnn W‘wvmum '''''' m:
1 1.... \" .......................... ,r— mar—s
1m \ -~~~—w""~.
o alliglnnlgnlljgnlll'LLlllgllllglmlnglllngIILglllI
0 5 10 15 20 25 30 35 4O 45 50
Tine(hr)
FIGURE 4.17: TP Reductions wIth 5.28 gIL of lee as the Chemlcal Coagulant
7000
,...x------"-"----~-----ilr
6000 _’.4"
’0
.’" Sampling
5000 ’7' Porttf
“m "’ -—e—-1
any... “'“2
... “2:.“Zjfilenm an .5. . ...... . ,_ ...... __ ' @— ~~*~~3
3°°° ~~--.\"-~o-.- ...................... A We...
~~~~~ ~ ..- -5
.._____I
1000 !
o I l I I T Y I ‘l T
0 5 10 15 20 25 30 35 4O 45 50

Sampling Tlrne (hr)

80

 

 

“...,

The results from pilot unit experiments where lime was used as the coagulant differed
from the laboratory results. Laboratory tests using lime to coagulate phosphorus resulted
in a treatment level of 5.29 g/L to meet the goals of the project. However, in the pilot
unit, much lower treatment levels (0.66 and 1.32 g/L of actual lime) produced results
similar to the optimum treatment from the laboratory experiments. Note that the best
phosphorus concentration reductions in the pilot unit occurred at 48 hours, laboratory
measurements ceased after 24 hours. The 0.66 and 1.32 g/L of lime treatment levels
produced the least amount of sludge and showed the largest reductions in SP and TP at
sampling points 3 and 4. The higher lime doses, 2.64, 3.96, and 5.28 g/L of actual lime,
produced no additional benefit when compared to the averaged phosphorus reductions

(Table 4.12) using 0.66 and 1.32 g/L of lime.

4.4.2.4 Chemical Coagulation with Metal Salts (Alum and FeCl;)

The two metal salts used in the chemical coagulation were alum and ferric
chloride (F eClg). Due the constraints of time and inclement weather, only a few trials
using metal salts were completed. Several trials were scrapped due to frozen valves or
hindered settling.

A discussed in section 4.3.3, the laboratory results using 4 g/L of alum met the
goal set forth at the beginning of the project, 80% reduction of SP and TP. A similar
dose of alum (3.17 g/L) was applied to liquid dairy manure in the pilot unit. Figure 4.18
shows the SP concentration reductions using 3.17 g/L of alum. Concentrations of SP in
liquid manure at the five sampling levels were lower after 1 hour. The initial reduction in

the SP (1 hour) is due to the binding of the SP with the cationic metal salt (alum). The

81

FIGURE 4.18: SP Reductlons mm 3.17 gIL Alum as the Chemlcal Coagulant

 

 

 

 

Sampling
Port #

 

 

 

 

 

"S

 

—+—1
~I-2
..*..3
“$3.4
—*-5

 

 

 
       
   

 

M‘s
.- or.— C‘- ”‘i '5“ ‘b c“;t".“— 0i

 

"U...
--_~..~* .....
.-

 

 

Time (hr)

FIGURE 4.19: TP Reductions with 3.17 gIL of Alum as the Chemlcal Coagulant

 

 

 

 

 

 

 

 

 

 

 

 

Tine (hr)

82

Sampling
Port #

 

—+—1
—u-2
"ens
wew4
-*-5

 

 

 

25 _ _ Liquid/Solid _
I I Interface
I — fit"
20 l '. ~‘ ul- ~24 hr —‘
.. ...... .48 hr
3
15 / - \
10 ' .
E ' ....m-m.‘
I I../::7'"“""~---:,‘:-~..
5 .- —————— _:-.-..-=m~---:-‘-*:e<""" W“ '
.cofl‘“.-’-... '3’. I
0 .5-:-:~,—~:-.—-.~-—.1h~:-:~.~-;-:*.. .:. ..:.. . .: . ....l....
40 35 30 25 20 15 10 5 0
SarnpleHeIghtIcm)
(measuredfrombottom)
l—O—Ohr-Ie-1hr~-*~-24hrs--O~-48hrsj
FIGURE 4.21: TP Mass Balance, Treatment 3.17 gIL of Alum, Pilot Unit
450
400 \.
35° Liquid/Solid
goo Interface
to .I—I .1hr
250 — -24 III
—— -48 hr
2...
100
50
0
40 35 30 25 15 1O 5

FIGURE 4.20: SP Mass Balance, Treatment 3.17gIL of Alum, Pilot Unlt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

20
Sample Height (cm)

(measured from bottom)
—O—0hr---I-1hr~v*--24hr~-O--48hrJ

 

83

coagulation reactions with alum (A1”) and FeC13 (Fe+°) occur faster than with lime
(Can). Section 2.5.1 in Chapter 2 offers more discussion of the reaction speed. After 24
hours, samples fiom ports 1, 2, and 3 showed 80% reductions in SP in the effluent. At 48
hours, the SP in the effluent at points 1, 2, and 3 was reduced by 90% or more. After 48
hours, samples from the deep sampling points (4 and 5) were slightly higher in SP than
the 24 hours samples. This is due to the settling of the non-coagulated phosphorus. The
raw data for the pilot unit experiments using metal salts as the coagulant is found in Table
A8 in the appendix. The graph of the TP reduction using the 3.17g/L of alum is
presented in figure 4.18.

Figures 4.19 and 4.20 display the same data as in Figures 4.17 and 4.18 with the x
axis acting as the sampling depth and the y axis as the phosphorus mass. The phosphorus
mass was calculated by assuming horizontal layering around the sampling ports with the
distance between ports split equally. Figure 4.20 shows a trend of increased phosphorus
concentration below the liquid/ solid interface.

As discussed earlier, FeCl3 was also used to coagulate phosphorus in the liquid
dairy manure at GMF using the pilot unit. The raw data for the experiment are found in
the appendix Table A9. Figure 4.21 is the graph of the SP reduction at each sampling
port with respect to time. Similar to alum, FeC13 is very aggressive at coagulating and
settling SP, hence the large reductions in SP. The treatment level for Figures 4.21 and
4.22 was 1.06 g/L of Fer. Figure 4.22 illustrates a difficulty when sampling a non-
homogeneous biological material like liquid dairy manure. Samples taken at Port 2 were
found to have less TP than samples at Port 1 at 24 hours and more TP than Port 3 after 48

hours. Table 4.11 demonstrates that there are differences in the horizontal plane of the

84

FIGURE 4.22: SP Reductions with 1.08 gIL of Peel, as the Chernlcal Coagulant

88

SP Concentration (%)
e s

150
100

FIGURE 4.23: TP Reductions with 1.06 gIL FeCI, as the Chemical Coagulant

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mm
mm
25°00
2 4000 ,,.oc--~-~----~-----*
O ’.‘
3000 ,w’ rrrrr ~$*"““““”’”:-~-' e
."‘..«~:--::"”""“‘~-.
0mm ,mf" “a“.
a T“... ..‘e
1000 k‘ “‘3‘ =04— °J‘_;..g—f
o I T T I l
o w m m w m w

Time (hr)

85

Sampling
Port if

 

—+—1
~I~2
--*--3
«new:
~u—5

 

 

 

Sampling
Port #

 

 

—e—1
—u—2
new-3
Mafia“;
-%-5

 

 

pilot unit, the coefficient of variance calculated in Table 4.11 was just under 10%.

Accepted book values can vary by as much as 30%. The FeC13 did not produce an

observable solid / liquid settling interface. Results varied and no observable settling

occurred.

86

CHAPTER 5

SUMMARY AND CONCLUSIONS

5.1 Summary

The goal of the project was to develop a strategy for managing the liquid manure
stream prior to storage and application to lessen the threat of environmental degradation.
For this project, chemical coagulation was selected as the method for separating
phosphorus from the liquid fraction of the manure stream. A variety of chemical
coagulants known to bind and coagulate phosphorus in wastewater treatment were tested.
The three that performed the best in the preliminary research were lime, alum, and ferric
chloride. Laboratory and pilot unit test demonstrated the usefulness of these coagulants
for concentrating the phosphorus in the sludge, while leaving a liquid fraction with little
or no phosphorus.

Based on the laboratory results, a pilot unit was developed to evaluate the
laboratory results on a larger scale and under real conditions. The pilot unit was a
combination of rapid mix chamber and settling tank. Similar reductions in the
concentration of both SP and TP in the liquid fraction were found in laboratory and pilot

unit tests.

5.2 Conclusions
5.2.1 Laboratory Experiments
0 The characterization of the liquid dairy manure stream at Green Meadow

Farms was completed for soluble phosphorus (SP), total phosphorus (TP),

87

chemical oxygen demand (COD), total solids (TS), volatile solids (VS),
and pH. The range found for each characteristic evaluated was within the
expected 43 0% range accepted for book values.

The Stannous Chloride Method for analyzing phosphorus concentration is
accurate and repeatable. The laboratory error resulting from the sampling
and analysis is well within the acceptable limits for biological materials.
Turbidity at the dilutions used in the laboratory (1/200) is notia useful
measurement for predicting SP or TP concentration. At lower dilutions
turbidity may be useful for predicting TP or TS.

Alum and ferric chloride achieved the goals of 80% reduction in both SP
and TP in the liquid fraction. Lime did not achieve the 80% goal for TP,
but did reduce SP by 80% after 24 hours of settling.

An economic analysis of the laboratory results showed that treating liquid
dairy manure for phosphorus reduction with lime is economical after 1 and
24 hours of settling. Alum was not economically viable after 1 hour of
settling, but after 24 hours of settling was economical. Ferric chloride in
the project proved to not be an economical option.

Polymers alone could not economically achieve the goal of 80%

reduction in phosphorus concentration set for this project.

88

5.2.2 Pilot Unit Experiments

Results of field trials with lime and ferric chloride in the 100 gallon pilot
unit were more positive than results of laboratory tests. However, alum
did not perform as well in the field experiments.

The differing results using similar treatments in both the laboratory and
pilot unit experiments may be attributed to variations in the day-to-day
characteristics (SP, TP, COD, TS, and VS) of the manure stream.

Daily temperature fluctuations seemed to play a role in the rate and
amount of settling occurring, however daily temperatures were not

recorded

89

LIST OF REFERENCES

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Wastewater. Washington DC: American Public Health Association.

Barrow J .T., H.H. Van Horn, D.L. Anderson, and RA. Nordstedt. 1997. Effects of FE
and CA Additions to Dairy Wastewater on Solids and Nutrient Removal by
Sedimentation. Applied Engineering in Agriculture. 13 2259-267.

British Sulphur Publishing. 1998. Phosphorus Availability in the 21"1 Century;
Management of a Non-Renewable Resource. Phosphorus and Potassium. Issue No: 217.

Burkholder, J .M., E]. Noga, C.W. Hobbs, et al. 1992. New “Phantom” Dinoflagellate is
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Chastain, J.P., MB. Vanotti, and M.M. Wingfield. 1999. Effect of liquid-solid
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Chemical Market Reporter. 2000. Schnell Publishing Company. 258125.

Copeland, C. 1996. Great Lakes Water Quality: Current Issues. Congressional Research
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Converse, J.C., RG. Koegel, and R]. Straub. 2000. Nutrient Separation of Dairy
Manure 8th International Symposium on Animal, Agricultural, and Food Processing
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90

Francois, RJ. and AA. Van Haute. 1985. The Role of Rapid Mixing Time on a
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of Phosphorus from Animal Manure a Review. Natural History Museum, London, UK.

Hashsham, S. 2000. ENE 802: Class Notes. Environmental Engineering Department,
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Hegg, R.O., R.E. Larson, A.J. Moore. 1981. Mechanical Liquid-Solid Separation in
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Hemenway DR, and K. Keshavan. 1968. Determination of Optimum Velocity
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Hudson, HE. 1965. Physical Aspects of Flocculation. Journal of the American Water
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Hudson, HE, and J .P. Wolfner. 1967. Design of Mixing and Flocculation Basins.
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Transactions of the ASAE. 27: 1854-1858.

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91

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92

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Von Bernuth, RD. and G. Salthouse. 1999. Manure and Fertilizer Nutrient Balance: A
Methodology Applied to Michigan. Applied Engineering in Agriculture. 15:695-700.

Zhang, RH. and F. Lei. 1998. Chemical Treatment of Animal Manure for Solid-Liquid
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Zhang, RH. and P.W.Westerman. 1997. Solid Liquid Separation of Animal Manure for
Odor Control and Nutrient Management. Applied Engineering in Agriculture. 13:385-
393.

Zhang, RH., X. Li, C.A. Collar, and RA. Fry. 2000. Aerobic Treatment of Dairy

Wastewater with Sequencing Batch Reactors. 8th International Symposium on Animal,
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93

TABLE A1: Manure Stream Green Meadow Farms
Date TP COD

       

<
(D

7/31/01 31 39
8/20/01 14
9/5/01 25
9/6/01 26
9/20/01
9/26/01
10/1/01
10/9/01
10/11/01
10/15/01
10/25/01
10/25/01
10/29/01
10/31/01
11/5/01
11/11/01
11/14/01
11/20/01
11l26/01
11l28/01
12/5/01
12/11/01
12/12/01
12/19/01
12/20/01
12/27/01
1
1
1
1
2/1

to

NN-t-A—L—L—LN-tN—k—L-AN

wwwwewww

u—B

NPNNQPP’S"

Aw

Deviation

94

TABLE A2: LABORATORY RESULTS USING LIME AS THE COAGULANT

   
    
  
 
 
    
  
   
   
 
   

   
      
   

  

Date: 12/12/2001
Treatment

Actual Lime

       
   

       
   

      
      

24 Hour
SP TP

Characterization
Parameters Results

1 Hour
SP TP

        

Jar

   

   
   

  
   
   
  

  
   

3411
1
1
11
1

TS
VS

5.
2.33

.61

     
  

   
      
      

  

Date: 12/19/2001
Treatment

Actual Lime

     

    

24 Hour
SP TP

Characterization
Parameters Results

        

    

      
 
 
  
   
  

Jar

 

     
 

37 TS

VS

 

11
1
1

  
   
 
 
   
    
     

.61

  

   
    
      

Date: 2/19/2002
Treatment

Actual Lime

      
    
   

     
      
 
  
 

24 Hour
SP TP

Characterization
Parameters Results

   

Jar

     
  

   
     

TS
VS

3.
2.23
1

95

TABLE A3: LABORATORY RESULTS USING ALUM AS THE COAGULANT

  
   

  
     
       
 
  
 

Date: 12/19/2001
Treatment

Alum

     
    
   

     
  

     
     

24 Hour
SP TP

Characterization
Parameters Results

1 Hour
SP TP

       

   

   

Jar

   

 

 

  
 

  
  

37
5

      

37
1

TS
VS

  
   
   
  
    

11
1

Date: 12/27/2001
Treatment

Alum

 
     

       
  

     
   
 
  
 
    
   
   
         

24 Hour
SP TP

Characterization
Parameters Results

        

    

  

Jar

   

 

   
   

  
   

TS
VS

5.
2.
43

   
   
    

  

Date: 3/5/2002
Treatment

Alum

      
 

     
   
 
 
  
  

24 Hour
SP TP

Characterization
Parameters Results

   

Jar

     
 
 
   

11 TS

VS

 

11
-1

96

TABLE A4: LABORATORY RESULTS USING FERRIC CHLORIDE AS THE
COAGULANT

Date: 12/27/2001
Treatment 1 Hour 24 Hour Characterization

Jar F SP SP TP Parameters Results

TS
VS

 

   
  

    
 

1/2/2002
Treatment

Date:

         
     

24 Hour
SP TP

Characterization

     
 
  
  
    
       

   

Jar Parameters Results

     
  

   
    

TS
VS

2.
2.1
44

TABLE A5: Horizontal Pilot Unit
Ports TP
Set Port #

97

TABLE A6: Pilot Unit
l2/2002

Reductions with No Chemical Additions

     

2.24 431
1 Hour 24 Hour 48 Hour
Treatment Soluble Total Soluble Total Soluble Total
Location

10/31/2001

1. 47
1 Hour 24 Hour 48 Hour
Treatment Soluble Total Soluble Total Soluble Total
Location
3701
11 1
21 4

3 3 701
1
1
3 1
3
4

11/14/2001

1.94 47
1 Hour 24 Hour 48 Hour
Treatment Soluble Total Soluble Total Soluble Total
Location

 

98

TABLE continued
11/28/2001
3.1 2. 39
1 Hour 24 Hour 48 Hour
Treatment Soluble Total Soluble Total Soluble Total

Location

 

99

TABLE A7: PILOT RESULTS USING LIME AS THE COAGULANT

10/9/01

3
Treatment

10/11/01

Treatment

10/15/01

2.
Treatment

2.
1 Hour 24 Hour 48 Hour
Soluble Total Soluble Total Soluble Total

211 981 211 981 211 981

1 31 81 1 451

1 761 1

1 7 7 1 71
8

1.84 29
1 Hour 24 Hour 48 Hour
cm Soluble Total Soluble Total Soluble Total

341

1.34 18 1
1 Hour 24 Hour 48 Hour

cm Soluble Total Soluble Total Soluble Total

 

100

TABLE A7 continued
1 0/25/01

2. 20.1 39
Treatment 1 Hour 24 Hour 48 Hour
cm Soluble Total Soluble Total Soluble Total

61
1

1 0/29/01

2. 2. 26
Treatment 1 Hour 24 Hour 48 Hour
cm Soluble Total Soluble Total Soluble Total

11/11/01

1. 1. 37
Treatment 1 Hour 24 Hour 48 Hour
Soluble Total Soluble Total Soluble Total

3161 3161 1 3161
1 1
1 1 1
1
4

 

101

TABLE A7 continued
1 1/20/01
2.
Treatment

1 1/26/01

2.
Treatment

1 2/6/01

Treatment

1. 39
1 Hour 24 Hour 48 Hour
Soluble Total Soluble Total Soluble Total

3 061 1 3 061 3 061
1 31 1 01
611 61 1 1 1
2 63 1 1 161
4 1
4 7

14 12

2. 43 1
1 Hour 24 Hour 48 Hour

cm Soluble Total Soluble Total Soluble Total

221 3 221 3 221 3
1 3 1

181 3 1 3 1

21 4 1 1 3

1 3 4

211 4

41

43
1 Hour 24 Hour 48 Hour

cm Soluble Total Soluble Total Soluble Total

3 051 1 3 051 1 3 051
1 91
1

 

102

TABLE A8: PILOT RESULTS USING ALUM AS THE COAGULANT
9/20/01
1. VS 1. 25 1
Treatment 1 Hour 24 Hour 48 Hour

cm Soluble Total Soluble Total Soluble Total

21 21 1 2

2. 2.1 1
Treatment 1 Hour 24 Hour 48 Hour
cm Soluble Total Soluble Total Soluble Total

 

TABLE A9: PILOT RESULTS USING FERRIC CHLORIDE AS THE COAGULANT
1 1/05/01
2. 1. 47
Treatment 1 Hour 24 Hour 48 Hour
cm Soluble Total Soluble Total Soluble Total

2

 

103

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