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This is to certify that the
thesis entitled

SOIL ENVIRONMENT MONITORING USING SENSORS TO
PREDICT MICROBIAL ORGANIC WASTE ASSIMILATION

presented by
ISIS L. FERNANDEZ-TORRES

has been accepted towards fulfillment
of the requirements for the

MS. degree in Biosystems Engineering

 

 

Major Professor’s S

Kim JR. J%fi

5'I/9 ?//z_oo 9/

Date

MSU is an affinnative-action, equal-opportunity employer

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PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before date due.
MAY BE RECALLED with earlier due date if requested.

 

DATE DUE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5f08 K:IProj/Acc&Pres/CIRC/DateDuemdd

SOIL ENVIRONMENT MONITORING USING SENSORS TO PREDICT
MICROBIAL ORGANIC WASTE ASSIMILATION

By

Isis L. Fernandez Torres

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Biosystems and Agricultural Engineering

2008

ABSTRACT

SOIL ENVIRONMENT MONITORING USING SENSORS TO PREDICT
MICROBIAL ORGANIC WASTE ASSIMILATION

By
Isis L. Fernandez Torres

Land application is a means of disposal and treatment for agricultural and
food processing waste. The soil’s waste assimilation capacity is governed by
biological activity. Waste decomposition is attributed to aerobic bacteria; however
multiple microbial communities coexist in the same environment. Microorganisms
adjust their community structure and biological activity to the surrounding,
environmental factors. Individual sensors were used to monitor four
environmental soil properties: soil moisture content, oxygen level, oxidation-
reduction potential and temperature. The sensors were placed in sand-filled
columns at three depths: 4, 12, and 20 inches.

Sensor readings varied with depth, hydraulic load (L/ac/day) applications,
organic loading (lbs BOD/ac/day) and nutrient availability. Microbial activity was
assessed by measuring iron and manganese concentrations present in soil
column Ieachate. Mobilization of manganese and iron is characteristic of
anaerobic microorganisms.

Soil moisture content, oxygen level and temperature sensors were
successful in estimating when anaerobic environmental conditions were most
favorable. The positive results from this research project provide confidence that

a field scale demonstration is warranted.

 

 

The

for a

 

ACKNOWLEDGEMENTS
The recipe for attaining a Master’s Degree is simple. Mix the ingredients below
for at least two years or until complete.
1 - Patient Advisor: Thank you Dr. Steven Safferrnan for taking a chance on
me and guiding me throughout these two years. I've learned so much.
3 — Sage committee members: Thank you Dr. Del Mokma, Dr. Daniel Guyer
and Steve Miller for the helpful advice and continuous guidance.
1 - Loving and supporting family: Mil gracias Pops for always encouraging
me; Mom for all the warm dinners; Nina for all those glucose rations and
nutrient mixes; Carlos for visiting me during my lonely times in the barn; and
Alex for ORP measurements.
1 - Resourceful better half: Dakujem moja laska for your help and your
never-ending, unconditional support.
1 - Fabulous Department: Thanks Barb for everything. Thanks Vicki and
John for all those leachate analyses. Thanks Lou and Alyse for the helping in
the daily tasks to keep the experiment running.
1 - Bundle of Friends: Thanks friends for all your support. Becky you ’ll

always be my personal genius. I would have never finished without you.

TABLE OF CONTENTS

ABSTRACT .......................................................................................................... i
ACKNOWLEDGEMENTS ................................................................................... iii
TABLE OF CONTENTS ...................................................................................... iv
LIST OF TABLES ................................................................................................ vi
LIST OF FIGURES ............................................................................................. vii
Chapter 1 Background ....................................................................................... 1
1.1 Land Application and Microbial Activity ....................................... 1

12 Soil Properties ............................................................................. 3

1_2_1 Soil Moisture Content .............................................................. 3

1.22 Oxygen Level .......................................................................... 4

1.23 Oxidation Reduction Potential ................................................. 5

1 24 Soil Temperature .................................................................... 7

12.5 Soil pH .................................................................................... 7

13 Soil Environment Monitoring ....................................................... 7

1_4 Problem Statement ..................................................................... 8

1 .5 Project Objective ......................................................................... 8
Chapter 2 Methods and Materials ..................................................................... 9
2_1 Sensor Description ...................................................................... 9

2.1 .1 Water Content Reflectometer ................................................. 9

2_1.2 Oxygen Sensor ..................................................................... 1 1

2.1.3 Oxygen Reduction Potential Probe ....................................... 13

214 Temperature Probe ............................................................... 14

22 Experimental Conditions ........................................................... 15

2.2;] Experimental Stage 1 ............................................................ 16

2.22 Experimental Stage 2 ............................................................ 17

2.2.3 Experimental Stage 3 ............................................................ 19

2.24 Experimental Stage 4 ............................................................ 19

23 Experiment System Set-up ........................................................ 20

231 Column Construction ............................................................ 20

2.3.2 Irrigation System ................................................................... 23

2.3.3 Sensor Wiring and Program Set-up ...................................... 24

2.34 Column Operations ............................................................... 26

235 System Maintenance ............................................................ 29

2.4 lnlluent and Leachate Water Monitoring ------------------------------------ 29

2.4.1 Chemical Oxygen Demand ................................................... 30

2.42 Dissolved Oxygen ................................................................. 30

2,43 onp ...................................................................................... 31

2_4.4 pH ......................................................................................... 31

24.5 Manganese and Iron Analysis ............................................... 32

2.5 Experimental Shutdown ............................................................ 33

26 Data Handling ........................................................................... 34
Chapter 3 Results and Discussion ................................................................. 35
3.1 Individual Sensor Evaluation for All Stages ------------------------------- 35

3.1 .1 Soil Water Content ................................................................ 36

3.1.2 Oxygen Sensor ..................................................................... 40

3.13 ORP Probes .......................................................................... 43

3.1_4 Soil Temperature .................................................................. 47

32 Stage 1 ...................................................................................... 49

3.2.1 Sensor Readings .................................................................. 50

322 Leachate Analysis ................................................................. 54

33 Stage 2 ...................................................................................... 56

331 Sensor Readings .................................................................. 56

3.3.2 Leachate Analysis ................................................................. 57

34 Stage 3 ...................................................................................... 60

3.4_1 Sensor Readings .................................................................. 61

3.42 Leachate Analysis ................................................................. 62

35 Stage 4 ...................................................................................... 66

3.51 Sensor Readings .................................................................. 67

3.5.2 Leachate Analysis ................................................................. 72

Chapter 4 Conclusions and Recommendations ............................................ 76
4.1 Conclusions ............................................................................... 76

4.2 Recommendations .................................................................... 77
APPENDIX A ..................................................................................................... 79
APPENDIX B ..................................................................................................... 86
BIBLIOGRAPHY ................................................................................................ 90

LIST OF TABLES

Table 2-1 Experimental Stage and Loading Summary ....................................... 16
Table 22. Sand Properties ................................................................................ 22
Table 2-3. lnfluent Daily Preparation Recipe Summary .................................... 27
Table 2-4. Composition of Substrate and Nutrient Solution per Stage ............... 28
Table 25. pH Ranges for Experimental Stage .................................................. 32
Table 3-1. Sample and Condition Summary ....................................................... 36
Table 3-2. Volumetric Water Content Statistical Analysis Summary .................. 39
Table 3-3. Depth and Stage Pair Comparison for VWC ..................................... 39
Table 34. Water Content calculations after Column Deconstruction ................. 40
Table 3-5. Oxygen Level Statistical Analysis Summary ..................................... 42
Table 3-6. Depth and Stage Pair Comparison for Oxygen ................................. 42
Table 3-7. ORP Minimum and Maximum Values ............................................... 44
Table 3-8. Post Calibration, ORP Sensor Reading in Standardized ORP SOIUIIOEG
Table 39 Post Calibration, ORP Sensor Reading in Anaerobic Digester Sludge17
Table 3-10. Temperature Statistical Analysis Summary ..................................... 49
Table 3-11. Depth and Stage Pair Comparison for Temperature ....................... 49

vi

 

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Figure 1-1.

LIST OF FIGURES

ORP relationship to oxygen availability and pH (McDaniel 2006) ...... 6

Figure 2-1. Campbell Scientific 08616 Water Content Reflectometer (Campbell
Scientific Inc. 2006) ..................................................................................... 10
Figure 2-2. Oxygen Sensor (Model O2S-D) by Apogee Instruments Inc. (Bugbee
and Blonquist 2007) .................................................................................... 11
Figure 2-3. HI 2005-1005 ORP Probe and Schematic (Hanna Instruments) ...... 13
Figure 2-4. Soil Column Dimensional Schematic with Drainage Holes .............. 21
Figure 2-5. Sensor layout ................................................................................... 23
Figure 2-6. Substrate and Nutrient Feed and Column Set-up, Top View ........... 24
Figure 2-7. Basic Sensor Wiring Diagram .......................................................... 26
Figure 3-1. All Stages - Volumetric Water Content ............................................. 37
Figure 3-2. All Stages - Oxygen Level ................................................................ 41
Figure 3-3. Oxygen Sensor Zero Off-set ............................................................ 43
Figure 3-4. All Stages — Temperature, all columns and all depths ..................... 48
Figure 3-5. Stage 1 - Volumetric Water Content ................................................ 51
Figure 3-6. Stage 1- VWC for Columns 4 and 5 during Stage 1 ......................... 52
Figure 3-7. Stage 1 - Oxygen Level ................................................................... 53
Figure 3-8. Stage 1 - Oxygen Level for Columns 4 and 7 .................................. 54
Figure 3-9. Stage 1 - Leachate Manganese and Iron Content ........................... 55
Figure 3-10. Stage 2 - Volumetric Water Content .............................................. 56
Figure 3-11. Stage 2 — Oxygen Level ................................................................. 57
Figure 3-12. Stage 2 — Leachate COD Concentrations ...................................... 58

vii

 

 

 

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Fig
Fig
Fig
Fig
Fig
Fig
Fig
Fig

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Figure 3-13.
Figure 3-14.
Figure 3-15.
Figure 3-16.
Figure 3-17.
Figure 3-18.
Figure 3-19.
Figure 3-20.
Figure 3-21.
Figure 3-22.
Figure 3-23.

Figure 3-24.

Figure 3-25.

Figure 3-26.

Stage 2, Leachate Manganese and Iron Content ........................... 59
Fungal Growth on Top Surface of Column 4 .................................. 60
Stage 3 - Volumetric Water Content .............................................. 61
Stage 3 - Oxygen Level ................................................................. 62
Stage 3 — Leachate COD Concentrations ...................................... 64
Stage 3 - Leachate Manganese and Iron Leachate Content .......... 65
Column 1 Top Surface, end of Stage 4 .......................................... 67
Stage 4 — Volumetric Water Content .............................................. 68
Stage 4 — Oxygen Level ................................................................. 69
65 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Level. 70
500 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Level71
1000 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Leve7l2
Stage 4 — Leachate COD levels ..................................................... 73
Stage 4 — Leachate Manganese and Iron Content ......................... 74

viii

 

 

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Chapter 1 Background

1.1 Land Application and Microbial Activity

Land application can be traced back as far as 1934 (Crites et. al. 2000). A
common form to treat organic, non-hazardous waste is land application which is
primarily used by the agriculture and food processing industries due to their rural
location. The efficacy to breakdown organic compounds is dictated by the soils
assimilative capacity which depends on biological activity. Microorganisms are
essential for organic waste decomposition and nutrient mineralization to simple
molecules for roots and plant uptake (Donker et al. 1994, US. EPA 1990).

Donker et. Al. (1994) state “microorganisms are suitable to act as a sharp
mirror of environmental pollution; they can function as a first warning system due
to their ubiquity, size, versatility and importance in foodwebs and recycling of
elements.”

When land application treatment systems are properly managed the
aerobic zones dominate (Crites et al. 2000, Brown and Caldwell 2007). Aerobic
decomposition is generally more rapid than anaerobic (US. EPA 1990). The
maintenance of an aerobic upper soil profile can be managed by controlling
organic loading, hydraulic loading and drying time (Brown and Caldwell 2007,
Islam and Wright 2006). Brown and Caldwell (2007), McDaniel (2006) and
Mokma (2006) report excess organic loading can result in odorous anaerobic
conditions, incomplete removal of organics in the soil profile and mobilization of

iron, manganese and other compounds.

Land treatment systems remove biodegradable organics primarily through
biological oxidation and reduction reactions (Crites et al. 2000). Under aerobic
conditions, the carbon source acts as the electron donor and oxygen acts as the
electron acceptor resulting in the aerobic-oxidation energy reaction shown below

(Tarradellas 1997, Rittmann and McCarty 2001).
C6H1206 + 602 —) 6 C02 + 6 H20

Once all the oxygen is consumed, anaerobic and facultative
microorganisms have more favorable growth conditions. The carbon source
remains the same but electron acceptor order shifts in a step-wise function to
nitrate (NOa'), manganese (Mn4*), iron (Fe3*), sulfate (SO42) and finally carbon
dioxide (002). The corresponding reduction reactions are listed below in

metabolic pathway order (Mokma 2006, Paul and Clark 1996, Ricks 2002).
2 N03" +10 e_+ 12 11* —> N2 + 6 H20 (denitrification)
Mno2 + 2 e‘+ 4 H+ —> Mn++ + 2 H20
Fe(0H)3 + e'+ 3 HT —> in,»++ + 3 H20
5042‘ + 8 e‘+ 9 H+ ——> HS— + 4 H20

C02+8e_+8H+ ——>CH4+2H20

The reduced forms of manganese Mn”) and ferrousiron (Fe2“) are more

soluble and can be mobilized into groundwater (Brown and Caldwell 2007). The

2

release of dissolved Fe2+ into groundwater is one of the most prevalent
groundwater problems worldwide (Lovley 2000). Lovley (2000) found ferrous iron
in groundwater causes plumbing and staining problems, negatively impacts plant
growth, and influences the composition and quality of groundwater.

“A number of food processing facilities in Michigan have been identified as
potential causes of groundwater impact (Mokma 2006).” Primarily because their
monitoring well water evaluations indicate elevated levels of iron (Fe),
manganese (Mn) and other water constituents above recommended values

(Mokma 2006).

1.2 Soil Properties

Microorganisms do not exist as single cultures, but rather coexist with
many different microbial communities. Microbial communities adjust their
structure and activity rate to environmental factors: temperature, soil moisture
content, oxygen availability, nutrient concentrations and energy sources (Dilly
2005, Donker et al. 1994, Islam and Wright 2006, US. EPA 1990, Tarradellas
1997). The following sections discuss how each soil environmental property

affect microbial populations.

1.2.1 Soil Moisture Content

Soil moisture content can be controlled via irrigation and drainage (EPA
1990) but is also dependent on precipitation and ground elevation. Moisture
content directly affects plant water availability, soil gas permeability, and
microbial presence, growth and activity (Leeson and Hinchee 1997, Paul and

Clark 1996, Tarradellas 1997). Aerobic microorganisms are usually affected by

3

 

1 I

soil moisture content and soil compaction (Neilson and Pepper 1990, Tarradellas
1997)

The degradation of organic compounds can be accelerated by maintaining
soil moisture content at an optimal level (US. EPA 1990). King et al. (1998)
found the optimal moisture content for aerobic bioremediation is between 20% to
50% field capacity. This range provides sufficient liquid moisture within soil pore
spaces for optimum cellular metabolism, reproduction and growth (King et al.
1998). However microbial population densities can vary greatly under extreme
conditions. Under low soil moisture, water may not be available for plant uptake
but active organism populations will exist. As moisture content increases, oxygen
permeability decreases (Leeson and Hinchee 1997). Neilson and Pepper (1990)
reported critical values for aerobic microbial respiration between 77°/o-97% soil
saturation values. Saturated soils lack oxygen in soil pores allowing anaerobic

microbial populations to predominate.

1.2.2 Oxygen Level

Oxygen is required for aerobic decomposition. Aerobes oxidize the
available carbon source and reduce oxygen to water. Tarradellas (1997) reported
reduced pore volume restricts oxygen exchange with the atmosphere and
creates the presence of water film barriers.

Yaniga and Smith (1986) observed an increase in the number of bacteria
with increasing oxygen concentration in soil columns treated with four different
oxygen-air mixtures. Smith and Dowdell (1974) monitored ethylene level, oxygen

level, moisture content and temperature at different depths in a sandy loam.

Their research showed a decrease in oxygen directly mirrored an increase in
residual ethylene because under saturated conditions, oxygen levels were
reduced from 20% to 12% - 14%. Hillel (1982) reported microbial respiration was
limited at values of 10% air filled porosity.

Bioventing is the process of aerating soils to stimulate in situ biological
activity and promote aerobic biodegradation (Leeson and Hinchee 1997). One
bioventing site studied by the US. EPA (1992) recorded initial oxygen values in
the range of 0% to 13%, which indicated oxygen limited biological activity.

Oxygen was added to this site to reach atmospheric levels.

1.2.3 Oxidation Reduction Potential

Oxidation-Reduction Potential (ORP) characterizes the oxygen status,
measures electron activity and the intensity of oxidation-reduction processes
(McDaniel 2006, Szogl et al. 2004). In microbial biodegradation studies,
reduction-oxidation conditions like aerobic, denitrifying, sulfate reducing,
manganese reducing, iron reducing and methanogenic are used to define the
electron acceptor involved in the conversion of the organic compound (Donker et
al. 1994). Soil reduction-oxidation potential, commonly termed redox potential,
ranges between -300mV to +900mV (Brown and Caldwell 2006, McDaniel 2006,
Pansu et al. 2001) Figure 1-1 shows a generalized relationship between soil
oxygen availability, ORP and pH. When soils remain at a low ORP for prolonged
time periods, metal reducing microbes transform iron and manganese to their
soluble, mobile valence states. These soluble metal particles are subject to

leaching and possible groundwater contamination (Brown and Caldwell 2006).

SoHEh
(mV)

 

+800

 

l l

 

 

r‘ « N T
+5” fig; aerobic
‘ hi h O
;.. . MhO, ( 9 2)
+400 " -- : +
- ----- Nil“
200 ". iii-:31:- ,3: : F§H IIIIIIIIIII . 31:31::
:“ - -’ ‘ lie—59;. low 02
._   ; {Sofi .. """ -.~.-6,Lli
~ Hg, anaero IC
4 5 6 7 9 10
Soil pH

Figure 1-1. ORP relationship to oxygen availability and pH (McDaniel 2006)

Bailey and Beauchamp (1971) measured ORP from soil samples to

determine nitrate reduction. His values dropped from an initial 400 mV value to

-300 mV range. Quispel (1947), Ricks (2002) and Szogl et al. (2004) used in situ

ORP electrodes to monitor redox potentials. All studies were performed on

waterlogged conditions. Ricks (2002) monitored ORP at different depths. The

most shallow electrode readings varied between 500mV to 700mV, and the

deepest electrodes had read between 200mV and 300mV. Szogl et al. (2004)

recorded ORP for the treatment of swine wastewater in three different

constructed wetlands. ORP values ranged from -100mV to >300mV. Quispel

(1947) attained negative readings in anaerobic soils at a 10 cm depth. Bohn

(1971) recommends reduction-oxidation potential monitoring should complement

and not replace oxygen level monitoring.

1.2.4 Soil Temperature

Soil temperature is an important factor that controls microbiological activity
and the rate of organic matter decomposition (Paul and Clark 1996, US EPA
1990). Islam and Wright (2006) reported soil microbial activity is greatest
between 20°C to 40°C; however Paul and Clark (1996) also state some microbes
grow in low temperatures, -12°C, while others under extreme heat, 110°C.

Temperature fluctuations such as cold shock, freezing and thawing cycles,
varying cool down and warm up rates, have effects on microbial populations

involved (Paul and Clark 1996, Tarradellas 1997).

1.2.5 Soil pH
Soil pH affects plant growth and bacterial growth (Crites et al. 2000). Near
neutral pH results in the largest and most diverse composition of bacterial
populations (Islam and Wright 2006b); specifically most known bacterial species
grow within the pH range of 4 to 9 (Paul and Clark 1996). Acidity, pH range of 4
to 6, enhances soil fungi activity (Islam and Wright 2006, Paul and Clark 1996). A
change in pH causes negative effects on certain microorganisms while others

microorganisms may thrive (Tarradellas 1997).

1.3 Soil Environment Monitoring

The use of sensors for soil environment monitoring is not uncommon.
Some irrigation systems are linked to moisture content probes to minimize water
use. Weather stations record soil moisture content and temperature. Szogl et. al.
(2004) monitored in-situ oxidation-reduction potential in constructed wetlands for

swine wastewater treatment using platinum probes. Ricks (2002) also used in-

7

situ ORP probes to monitor the effects of riparian buffers and vegetation on
groundwater nitrate concentration. No literature was found on combined use of
available soil property sensors to provide insight on microbial presence and
activity which is the main focus for this project. The commercially available

sensors used in this project are described in detail in the following chapter.

1.4 Problem Statement

Finding and determining prescriptive, acceptable organic and hydraulic
loadings is difficult due to the complexity of soil assimilation. However, by
monitoring the soil environment a tool can be developed to prevent over loading
the soil and the resulting impacts to groundwater associated with metal

mobilization caused by anaerobic microbial communities.

1.5 Project Objective

The project’s objective is to determine if changes detected by soil property
sensors can be associated to metal mobilization caused by anaerobic microbes.
The monitored soil properties were volumetric water content, oxygen level,
oxidation reduction potential, and temperature. Sensor response changes were

obtained by varying organic waste application.

Chapter 2 Methods and Materials
Soil environmental conditions are theorized to predict microbial activity
and in tum, used to estimate soil’s assimilative waste capacity. To test, soil
columns were assembled and soil property sensors were installed to measure
important soil environmental conditions (section 2.1) at various depths (section
2.3).
. A water content reflectometer was used to measure soil moisture content
0 Oxygen level was determined by an oxygen sensor
. Oxidation-reduction potential (ORP) was monitored with a platinum
electrode
. A thermistor was used to measure soil temperature
Each soil column was equipped with twelve sensors: 3 water content probes, 3
oxygen sensors, 3 ORP electrodes and 3 therrnistors. One sensor of each kind
was place at three depths (4 in., 12 in. and 20 in. below ground) within the soil
column to measure variability by depth.
Columns were operated with various hydraulic and organic loadings and
nutrient concentrations varied between columns and research stage (section 2.2).

Images in this thesis chapter are presented in color.

2.1 Sensor Description

2.1.1 Water Content Reflectometer

Soil volumetric water content (VWC) was monitored using the Campbell
Scientific 08616 water content reflectometer, Figure 2-1. The probe uses time

domain measurement methods to calculate volumetric water content.

9

Figure 2-1. Campbell Scientific CS616 Water Content Reflectometer (Campbell

Scientific Inc. 2006)

An electromagnetic pulse signal is emitted and received through the
stainless steel rods at a velocity dependent on the dielectric permittivity of the
surrounding soil (Campbell Scientific Inc. 2006). The soil’s dielectric permittivity is
dependent on water content and inversely proportional to the pulse velocity. The
travel time of the signal along twice the rod length is measured. This time period

is used to calculate the volumetric water content using Equation 21.

VWC = — 0.0663 - 0.0063 * period + 0.0007 * period2 Eqn 2 — 1

The 08616 water content reflectometer measures from 0% water content
to saturation. Saturation values for sandy soils, as measured by the C8616 probe,

can vary from 0.30 to 0.42 volumetric water content‘. Other operational

 

1 Jason Ritter, Campbell Scientific Inc. Engineer, personal communication, January 14,

2008.

10

characteristics of the 08616 water content reflectometer are an accuracy of
12.5% VWC, resolution and precision of 0.1% VWC, and a probe-to—probe
variability of 11.5% VWC in typical saturated soil.

Several factors that can reduce measurement accuracy are high soil
electrical conductivity, high soil organic matter and high clay content. Air voids
around the rods should be avoided during installation to optimize sensor

accu racy.

2.1.2 Oxygen Sensor
The amount of oxygen (02) gas in air was measured using the 028-D
oxygen sensor designed and manufactured by Apogee Instruments Inc., located
in Logan, UT. This sensor measures absolute gas concentration level, but reads
out in relative units of oxygen (%) to other gases present in the mixture. Historical
atmospheric concentration of 02 has remained at 20.95%. The absolute 02
concentration determines the rate of most biological and chemical processes but

the relative 02 is typically reported (Bugbee and Blonquist 2007).

 

Figure 2-2. Oxygen Sensor (Model O2S-D) by Apogee Instruments Inc. (Bugbee

and Blonquist 2007)

11

Bugbee and Blonquist (2007) describe the Apogee 02 sensors as
“galvanic cell sensors made of a lead anode, gold cathode, acid electrolyte and
Teflon membrane, where Oz diffusion occurs. The current flow between the two
electrodes is linearly proportional to the absolute amount of 02 in the soil
environment. A resistor is used to produce a voltage (mV) output instead of a
direct current output.” The sensors are equipped with a small resistance heater
which is designed to warm the sensor slightly above ambient temperature
keeping condensation from occurring on the Teflon membrane.

The output of the Apogee 02 sensor is a linear function of absolute 02
concentration. A single-point calibration is generally used to derive a calibration
factor (CF) (Equation 2-2) used to convert mV output from the sensor to relative
02 concentration (%). The oxygen sensor can measure between 0 to 100% 02
however, under anoxic conditions a zero offset was observed, reference section
3.1.2. Additional sensor specifications are accuracy of <0.01% 02 drift per day

and a operational range 0° to 50°C.

20.95%
mVC

CF:

 

Eqn 2-2

where, ch is the mV reading at time of calibration

Under aerobic conditions Oz level (%) is predicted to remain approximately
20.95%, in contrast to anaerobic conditions where predicted values are below
10% oxygen. Hillel (1982) found that biological activity is restricted at levels of

10% oxygen of air filled porosity.

12

2.1.3 Oxygen Reduction Potential Probe

Oxidation-reduction potential (ORP) is used to measure the electron
activity in soil and is commonly measured in millivolts. The Hanna Instruments
ORP electrode with PFT E junction, model HI2005-1005, was selected to monitor
soil oxidation-reduction (redox) values. This is a flat tip platinum probe with a
ground loop matching pin and a BNC connector as shown in figure 2-3. The ORP
value is the measured difference between the potential of the reference half-cell

and the potential of the platinum electrode.

 

Polymer Electrolyte

I

Reference Half Cell

   

Pt Sensor a“

 

Matching PIN

 

 

 

Figure 23 HI 2005-1005 ORP Probe and Schematic (Hanna Instruments)

Redox reading errors can be attributed to clogged electrode tips or
scratched surfaces. The sensor will become sluggish under these conditions.

Under aerobic conditions, 02 is the preferred electron acceptor; expected
ORP values are greater than +300mV dependent on soil pH (McDaniel 2006,
Szogi et al. 2004). Saturated soils are oxygen deficient and preferred electron
acceptors shift. Anaerobic microbial respiration electron acceptor preference is
nitrate, manganese oxide, iron oxide, sulfate and carbon dioxide (Patrick et al.

1985). Manganese and iron oxidation occurs in the ~100mV to 300mV range

13

(McDaniel 2006, Szogi et al. 2004). A shift from aerobic conditions to anaerobic

conditions should result in negative linear trends.

2.1 .4 Temperature Probe

The Campbell Scientific T108 temperature probe uses a BetaTherm
100K6A thermistor to measure temperature. An excitation voltage of 2.5 V is
applied and the voltage drop across an integrated 1 K ohm resistor is measured.
The ratio of measured voltage (Vs) to the excitation voltage (Vx) is related to
thermistor resistance (Rs) using Equation 23 (Campbell Scientific Inc. 2007). A
Rs value converts the resistance to temperature in degrees Celsius using the

Steinhart-Hart equation (equation 2-4). The Steinhart-Hart equation error is less

 

 

than :0.01°C.
XS—z 1000 Eqn 2—3
Vx (Rs +40000+1000)
T (°C)= 1 —273.15 Eqn 2—4

(A + B (In Rs) + C (In Rs)3)
where,
A=8.27lllle—4
B = 2.088020 e - 4
C = 8.059200 e — 8

The T108 probe can measure air, soil and water temperatures in the
range of -5°C to +95°C. Therrnistor interchangeability error is less than :0.2°C.
Long lead lengths and electrically noisy environments should be avoided to

minimize error.

14

2.2 Experimental Conditions

The experiment was divided into four stages. Stage 1 only varied hydraulic
loading. Hydraulic loading remained constant in the remaining three stages
however, biochemical oxygen demand (BOD) loading and nutrient concentrations
were varied. During each stage there were duplicates for every condition tested,
except during stage 4 where triplicates of each condition existed. Columns 2 & 7
were used as control conditions for stages 2, 3 and 4. Table 2-1 is a summary of
each experimental stage and its loading conditions. Each stage’s variables are

further described in sub-sections below.

15

Table 21 Experimental Stage and Loading Summary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Column Hydraulic BOD Loadin Nutrient
Stage Stage Dates Number (b23023) (LBS/aclday? Loading (%)
2 8 7 2 0 0
1a 7/24/07 - 1 8 8 2 0 0
8/15/07 3 & 6 2 0 0
4 8 5 2 0 0
2 8 7 1 0 0
1b 8/16/07 - 1 8 8 0 0 0
9’207 3 8 6 2 0 0
4 8 5 4 0 0
9,3,07 _ 2 8 7 2.4 0 0
10 10/2/07 1 8 8 2.4 0 0
'Pump “me“? 3 8 6 2.4 0 0
installed
4 8 5 2.4 0 0
2 8 7 2.4 65 0%
2 10/3/07 - 1 8 8 2.4 65 25%
12/23/07 3 8 6 2.4 65 50%
4 8 5 2.4 65 100%
2 8 7 2.4 65 0%
3 12/29/07 - 1 8 8 2.4 65 25%
35/03 3 8 6 2.4 65 50%
4 8 5 2.4 500 100%
2 8 7 2.4 65 0%
4 2/5/08 - 3/3/08 1, 3 8 8 2.4 1000 100%
4, 5 8 6 2.4 500 100%

 

 

 

 

 

 

 

2.2.1 Experimental Stage 1

Hydraulic loading was the only variable during stage 1; no BOD loading or
nutrients were introduced to the columns. All columns were watered with

dechlorinated tap water. The chlorine was removed from the tap water by adding

16

 

 

aria

Dec

con
dec
COIL
test

WGI

On
Pro
floc
tim

SEC

SEC

inE

an aquarium water conditioner, Instant Dechlor by WECO Products Inc. Instant
Dechlor ingredients are sodium thiosulphate, sodium bicarbonate and waterz.

Stage 1 was further divided into 3 separate phases. All the sensors were
connected to the main circuit boar during the first three weeks. Meanwhile 2 L of
dechlorinated water were applied manually to the top surface area of each
column daily. On August 16, 2007, day 23, the hydraulic loading was varied to
test if the volumetric water probes would indicate change. Four hydraulic loads
were tested:

. 0 L per day

- 1 L per day

. 2 L per day

- and 4 L per day
On August 21, 2007 column 4 was flooded with approximately 35 L of water to
promote sand settling. Seven days later, the remaining seven columns were also
flooded. On September 3, 2007, day 41, the pumps were connected to automatic
timers to spray 2.4 L per day in four doses of 600 mL each, further described in

section 2.3.2. All columns were treated equally until Stage 2.

2.2.2 Experimental Stage 2

The first day of stage 2, all columns were seeded with 1L of unchlorinated
secondary treatment effluent from the East Lansing Wastewater Treatment Plant

in East Lansing, MI, to introduce a variety of microorganisms to each column.

 

2 Robert Brine, WECO employee, personal communication, December 7, 2007

17

 

 

 

COT

on'
L0
grc
ea
ca;
Th

CO'

BC
lite
Mil

53

Th

During stage 2, the organic BOD loading remained constant but nutrient
concentration was varied. The tested conditions follow.

- 65 lbs BOD/ac/day and 0% nutrient concentration mix

65 lbs BOD/ac/day and 25% nutrient concentration mix

65 lbs BOD/ac/day and 50% nutrient concentration mix

65 lbs BOD/ac/day and 100% nutrient concentration mix

The nutrient solution was introduced to create oxygen limiting conditions
only; however 0% and 25% nutrient conditions could also be nutrient limiting.
Low nutrient concentrations were introduced to prevent excessive microbial
growth which could potentially clog the soil columns. The water irrigated on to
each column was composed of dechlorinated tap water, nutrient solution and a
carbon source. D-glucose, commonly termed dextrose, was the carbon source.
The nutrient solution formulation is described in section 2.3.4 and has a
concentration based on oxygen demand.

BOD loading was controlled and fixed for all columns at 65 lbs
BOD/acre/day, the median from the data collected by Mokma (2006). Mokma’s
literature review collected organic loading data presently being land applied by
Michigan food processors. Glucose has a theoretical oxygen demand (ThOD) of
533mg/L, calculations shown below.

C6H1206 + 602 —) 6C02 + 6H20

 

500 mg glucose . lmmol glucose . 6 mmol 02 . 32 mg 02

ThOD = = 533.33 “—5

L 180 mg glu cose 1 mmol glu cose 1 mmol 02

18

The hydraulic loading was calculated based on a concentration of 500 mg

BOD/L and a BOD load of 65 lbs BOD/ac/day.

Hydraulic loading = BOD loading - BOD concentration - surface area

”’3 BOD - 4535924 3’5 - —l—L——. 7r (0.752)sz2 -£°— = 2.40i

Hyd. loading = 65
ac - day lb 500 mg 43560 fiz day

 

Daily 2.4 L of wastewater was sprayed onto each column in four 600mL
doses spaced out every 6 hours. For the following two stages, hydraulic load
remained at 2.4 L per day and BOD loads and nutrient concentrations were

increased.

2.2.3 Experimental Stage 3

In stage 3, only one experimental condition was varied from stage 2. The
100% nutrient condition was increased from 65 lbs BOD/ac/day to 500 lbs
BOD/ac/day. The nutrient concentration remained at 100% but proportions were

adjusted to the new oxygen demand requirements.

2.2.4 Experimental Stage 4

Organic loading was varied in stage 4 to increase the oxygen consumption
rate. Conditions tested were included in the following.

- 65 lbs BOD/ac/day at 0% nutrient concentration mix (control)

- 500 lbs BOD/ac/day at 100% nutrient concentration mix

- 1000 lbs BOD/ac/day at 100% nutrient concentration mix
The experiment’s control condition was maintained at 65 lbs BOD/ac/day with 0%

nutrient concentration for the entire experimental period; stages 2, 3 and 4.

19

 

 

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cap a
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andc

 

2.3 Experiment System Set-up
This section discusses the set-up of the columns, sensor electrical wiring,
daily soil column operations and experimental maintenance and column

deconstruction.

2.3.1 Column Construction

All eight columns were constructed using 18 inch inner diameter, single
wall, corrugated drainage pipe. The corrugated material wall was selected to
prevent water flow short circuits along the edges of the columns.

A split-end cap was placed as the base for each vertical column. The split
portion of each end cap was secured with three, industrial strength zip ties and a
rectangular piece of hard plastic was caulked at the split to prevent leaks from
the base. To allow for drainage, eleven 1/8 inch holes were drilled in each end
cap as depicted in Figure 2-4. A clear, plastic container was placed below each
soil column to collect Ieachate.

Each column had doors cut on the sides at each sensor depth to allow for
access to the sensors and soil sample collection. Sensor wires exited from the
sides of the soil column. Figure 2-4 is a dimensional schematic of each column

and depth indication.

20

Column Height:
38 in.

Sand Fill Height:
~24 in.

AP"

‘LV

 

 

Column ID = 18 in.

.—._._._._.—.—.—.—.—.—._._.—..g

4'

 

fi-----------------—_---~-—-—-

..............................

 

 

 

 

.---—-—-———--—--_-----------—

 

 

 

Drainage Hole Layout

DEPTH A: ~4 in.

DEPTH B: ~12 in.

DEPTH C: ~20 in.

Figure 2-4. Soil Column Dimensional Schematic with Drainage Holes

A layer of pea gravel was placed on the bottom of the column. The gravel

particles were sieved to a range of greater than 2.00mm and less than 4.75mm.

2000mL of pea gravel was placed on the bottom of each end cap and spread

across the entire end cap surface area.

Each column was filled with play sand purchased from a local hardware

store in 50 lbs bags. The sand used in this experiment was characterized by the

Michigan State University Soil and Plant Nutrient Laboratory in East Lansing,

Michigan, and characterization results are listed in Table 2-2.

21

Table 22. Sand Properties

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

. . . Test Date Test Date

Play Sand Characteristics Umt 6/12/2007 8/1/2007
Soil Nutrient Levels

Soil pH ppm 7.8 8.2

Phosphorus (P) ppm 7 5

Potassium (K) ppm 12 12

Magnesium (Mg) ppm 47 53

Calcium (Ca) ppm 929 795
Micronutrient Level

Zinc (Zn) ppm n/a 2.6

Manganese (Mn) ppm n/a 27.3

Copper (Cu) ppm n/a 1.6

Iron (Fe) ppm n/a 107.5
CEC meq/100 g 5.1 4.4
% of Exchangable Bases

Potassium (K) % 0.6 0.7

Magnesium (Mg) % 7.7 9.9

Calcium (Ca) % 91.7 89.4
% Organic Matter % n/a 0.20
Nitrate (N) ppm n/a 0.2

 

 

 

 

In step 1, sand was added to each column up to the door at depth C. The

22

sand was compacted by adding water. Then each sensor was carefully placed in
its assigned location as shown in Figure 2-5. All sensor wires were threaded
through the door opening before it was secured with industrial strength duct tape
to prevent leaking. After placing the sensors, sand was carefully placed not to
disturb the sensors and then built up to depth B, in the same orientation shown in
Figure 2-5. The same steps were repeated for the top sensors. Each column

required approximately 450 lbs of sand. All columns were constructed the same

 

_ 5 \g,
'1

. I I ‘\ i . I '. ‘T \
' ,i ORP Probe . ' . . -',.,g‘y~‘:‘f Thermistor ‘,
I: 9 ‘ Oxygen Sensor g:

.:‘ _ w. “w... '

WC Reflectometer

"3.1. 1 lug ~ ‘ _.
\ 1h

N—‘V ‘

0‘ ‘
N ‘. .-

. ‘c . -
. ‘ 1‘
\.
. ‘7 . .
, i‘

l

A
I

 

Figure 2-5. Sensor layout

2.3.2 Irrigation System
A full-cone spray nozzle was affixed above the soil column so its spray
would cover the top surface area. Each experimental condition was assigned to
one single influent feed resulting in a total of 4 water feed tanks for stages 1-3, as
each condition had duplicated columns. Each influent bucket had two outlets,
each to an individual pump assigned to one soil column. The pump used in the
experiment is a multipurpose pump, 114 Volts AC with a maximum flow rate of 5

GPM that was purchased at a local hardware store. A standard garden hose was

23

attached from the influent bucket to the inlet of the pump. The pump outlet was
fitted down to a M: in ID clear rubber tubing that fed to each individual column.

Figure 2-6 are pictures of the influent set-up and a top view of all eight columns.

 

Influent Bucket:
Substrate and Nutrient Feed

 

 

   

Figure 2-6. Substrate and Nutrient Feed and Column Set-up, Top View

Each pump was connected to an analog, cyclical timer set to activate

every 6 hours. The spray for each pump was calibrated to dose 600 mL.

2.3.3 Sensor Wiring and Program Set-up
This experiment used a total of 96 sensors, 24 sensors for each soil,
environmental property. During column construction after placing each sensor in
the indicated location, it was labeled with column number, depth location and
environmental property. The sensors were grouped by environmental property for
wiring to the main circuit board. Figure 2-7 is a basic representation of the

electronic set-up for the sensors to the data acquisition system.

24

The moisture content sensors where connected to a AM16/32 Campbell
Scientific multiplexer, which was connected to the CR1000 Campbell Scientific
datalogger. Similarly all the therrnistors were connected to a second multiplexer
and oxygen sensors required to be connected to two additional multiplexers. The
datalogger was connected to a stationary computer and programmed to record
measurements every 5 minutes. The data were downloaded onto the computer
twice a week.

The ORP electrodes could not be incorporated into the main circuit board
due to the BNC connector. Consequently each ORP reading was manually taken
and recorded only once daily. In order to take an ORP reading, each ORP
electrode was connected to a controller with a read out screen (Hanna
lnstrument’s HI 504 Series pH/ORP controller with Tele-Control and Sensor
Check). After approximately 1 minute, the stabilized mV reading was recorded
then the controller was connected to the next ORP electrode until all

measurements were taken.

25

 

Sensor

j Column # / Depth

 

(#lA Moisture Content I—>

 

 

lit/B Moisture Content I—>

 

 

 

l
l
I‘

Iii/C Moisture Content l—2

 

iii/A Oxygen Sensor

 

fit/B Oxygen Sensor

 

 

.#/C Oxygen Sensor

 

 

 

#IA Temperature

 

,#/B Temperature

 

 

 

#IC Temperature

Multiplexer
(MUX)

 

YYY

MUX A:
Moisture
Content

 

 

VVV

MUXB:

Oxygen Level "

Data Acquisition (DA Q) System

 

 

 

>1
)4

MUXC:
Oxygen
Temperature

 

CR1000

DAQ Power Req:

1 2VDC

— ;« “2.5V Excitation

 

 

 

 

vvv

 

MUXD:
Temperature

 

 

 

Figure 2-7. Basic Sensor Wiring Diagram

2.3.4 Column Operations

The experimental set-up required daily influent wastewater preparation

and daily leachate measurements. Influent preparation consisted of mixing

unchlorinated tap water, with the appropriate glucose ration (BOD loading) and

nutrient solution, if required (Table 2-3).

26

 

Table 2-3. Influent Daily Preparation Recipe Summary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Influent Daily Preparation Recipe
Column Dechlorinated Glucose Nutrient Soln
Stage Influent Spray Water Ration (%)
(Ll (m9)
1 a n/a n/a 2 0 0
n/a n/a 0 0 0
n/a n/a 1 0 0
1b
n/a n/a 2 0 0
n/a n/a 4 0 0
1c n/a n/a 2.4 0 0
1 1 & 8 8 4000 25%
2 2 2 & 7 8 4000 0%
3 3 & 6 8 4000 50%
4 4 & 5 8 4000 100%
1 1 & 8 8 4000 25%
3 2 2 & 7 8 4000 0%
3 3 & 6 8 4000 50%
4 4 & 5 8 30800 100%
1 1, 3 & 8 8 30800 100%
4 2 2 & 7 8 4000 0%
4 4, 5 & 6 8 61600 100%

 

 

The nutrient solution was based on Trulear 81 Characklis (1982) substrate

formulation with concentration oxygen demand (in Table 2-4).

27

Table 2-4. Composition of Substrate and Nutrient Solution per Stage

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28

2.3.5 System Maintenance

The experimental set-up required biweekly water flow checks for each
pump to maintain the hydraulic loading at 2.4 L/day. This loading was dispersed
over 4 sprays. Each spray was calibrated to 600 mL as needed during water flow
checks. All pumps were inspected daily for proper operation. Pump impellers
were replaced as required.

During stages 3 and 4, the nozzles had to be routinely inspected and
cleaned as they clogged due to bacteria growth within the influent buckets. At
times the influent with added nutrient solutions would present excessive bacterial
growth characterized by a rotten egg-like smell and floating, black masses and
negative ORP readings. At the first sign of any of the symptoms previously
described, the bucket and hoses were flushed with hydrogen peroxide solution

and rinsed with water until clean.

2.4 Influent and Leachate Water Monitoring

Influent and soil column leachate was analyzed weekly for chemical
oxygen demand (COD), dissolved oxygen (DO), ORP, temperature and pH.
Influent samples were collected at each influent tank location before new influent
preparation was mixed. The leachate was sampled from each soil column’s
effluent collection bucket. Samples for COD testing were always collected from
fresh effluent.

In addition to water analysis parameters, the influent and effluent was

analyzed for concentrations of iron and manganese twice a week. The presence

29

of manganese and iron in the Ieachate indicate mobilized metals from anaerobic

reduction-oxidation reactions.

2.4.1 Chemical Oxygen Demand

COD evaluated the organic load assimilated by the soil column and its
microorganisms. BOD is comparable to COD, since COD testing measures
chemically oxidizable organic matter. BOD testing relies on bacteria to oxidize
organic matter and takes five days to complete, unlike COD which can be
completed in two hours.

The EPA approved reactor digestion method, Hach Method #8000, was
used. Reagent range 20 to 1500 mg/L was used for the influent samples and 0-
150 mg/L for the Ieachate samples. Each sample volume was separated into two
separate samples, allowing for laboratory duplication and an assessment of
precision. Each time a COD test was conducted, a blank sample prepared from
deionized water and a standard sample were run. The standard sample was
prepared from a known quantity of standard solution sample purchased from
Hach.

During two occasions COD testing was performed on freshly prepared
influent and at each spray nozzle location. Both values were compared to COD
values collected the next day directly from the feed container. Significant

differences were not found.

2.4.2 Dissolved Oxygen

Dissolved oxygen of each sample was determined weekly using a DO

probe (Oakton D0300 series Data Meter). DO levels help indicate oxygen

30

limiting conditions. Influents with added nutrient solution were consistently found
to have significantly lower levels of DO, ranging from 0.65 mg/L to 3.00 mg/L,
than the Ieachate. The lower influent DO levels indicate that microbial biological
decomposition was occurring in the influent buckets with added nutrient solutions.
The control influent location, columns 2 & 7 had no added nutrients and ranged
from 5.05 mg/L to 8.77 mg/L.

All Ieachate samples were consistently saturated with oxygen, ranging
from 6.41 mg/L to 10.49 mg/L. Saturated conditions are attributed to the
continuous Ieachate drip into the collector allowing for constant aeration and not

thought to be representative of the conditions within the column.

2.4.3 ORP
An ORP probe, Oakton Waterproof ORP Testr 10 manufactured by

Eutech Instruments, used for water quality testing was submerged in the weekly
collected samples to determine ORP values (mV). The influent ORP ranged from
87 to 197 mV except on two occasions when ORP values were -10mV and
-167mV. The negative readings indicated anaerobic conditions were present in
the influent bucket. The bucket was immediately cleaned with hydrogen peroxide
and rinsed with water. The effluent readings ORP values ranged from 53 mV to

225 mV.

2.4.4 pH

The pH of each sample was determined weekly using a pH meter,
Accumet Excel XL60 pH probe. Before each use the pH meter was tested for

accuracy using a 3 point pH calibration buffer solution to a :0.05 pH units

31

tolerance. If any of the readings fell out of this range, the pH meter was
recalibrated.

Influent with added nutrient solutions yielded a lower pH level than when
no nutrient solution was added. All Ieachate samples had higher pH values than

their influent. Table 2- 5 summarizes the pH measurements.

Table 2-5. pH Ranges for Experimental Stage

 

 

 

 

 

 

 

 

 

 

 

 

Stage I pH min I pH max
Influent

2 | 6.05 | 8.44
3 | 5.24 | 8.06
4 | 4.62 | 7.88

- Leachate
2 l 6.98 I 8.81
3 | 6.22 l 8.42
4 | 6.05 l 8.43

2.4.5 Manganese and Iron Analysis

During stages 2, 3 and 4, influent and Ieachate samples were collected
biweekly from each column and analyzed by the Michigan State University Soil
and Plant Nutrient Laboratory in East Lansing, Michigan for manganese and iron
concentrations.

The laboratory used flame atomic absorption. In this method, as described
by ASU (2008), samples are introduced into a hot-flame which atomizes the
metal of interest. A lamp of desired wavelength and a detector measure

absorbance values based on the amount of the metal present. When compared

32

to a generated standard curve, the metal of interest can be quantified. Detection

limits vary according the metal under consideration, and is reported in ppm units.

2.5 Experimental Shutdown

At the end of the Stage 4, three columns were selected to be
disassembled in order to recover all sensors and perform post-calibration
procedures. The remaining columns were used for continued testing beyond the
scope of this thesis. The dismantled columns were the following: Control Column
7 - exposed to 65 lbs BOD/ac/day during stages 2, 3 and 4, Column 1 - exposed
to 1000 lbs BOD/ac/day during stage 4 and Column 5 — exposed to 500 lbs
BOD/ac/day during stages 3 and 4.

Prior to dismantling each column, soil samples were collected from each
sensor depth for microbiological phospholipid analysis as part of another project.
The deconstruction of each column was handled in a systematic manner to
minimize damage to sensors. Pictures were recorded throughout the dismantling
process as documentation, as discussed below.

First, a picture was taken of the soil column top surface. Secondly sand
was removed until the first sensor cluster at depth A was exposed. A sand
sample was collected and immediately weighed for soil water content and volatile
solids calculations. Also, the color of the sand was matched to Munsell (2000)
soil color charts for descriptive purposes. Each sensor was disconnected from its
multiplexer connection and carefully inspected for scratches, dents and any other
abnormalities. The same steps were followed at each depth. An additional sand

sample was collected from the very bottom of each soil column.

33

Volumetric water content was correlated to the collected sand sampled
during column deconstruction. After recording the wet sample weight, the
samples were dried in a convection oven at 104°F for 20 hours. Dry sample
weight was recorded. Volatile solid content was also determined by weighing the
dry samples after placing them a furnace at 550°F for one hour.

After column deconstruction, ORP probes and oxygen sensors were post
calibrated. The post-calibration procedures of the oxygen sensor consisted of
recording oxygen level measurements at atmospheric and anoxic conditions. The
anoxic conditions where created by placing the oxygen sensor in a nitrogen filled
glass chamber filled. The oxygen was flushed out of the system while nitrogen
was added until the sensor readout reached a stable condition.

The ORP probe was rinsed with deionized water and submerged in a
standard ORP solution (YSI ® Zobell solution). Both temperature and ORP
reading of the solution were recorded. In addition to standardized solution, each
probe was also submerged into anaerobic digester sludge collected from the
Swine Laboratory at Michigan State University in East Lansing, MI.

All post-calibration data is located in Appendix A.

2.6 Data Handling

The sensor data was downloaded from the datalogger twice a week.
Individual plots were created for each environmental property for each column. At
times, due to power source fluctuations data points in all columns would jump out
of range, but immediately return to previous reading. In this event, the data point

was erased for data continuity.

34

Chapter 3 Results and Discussion

Each soil environment parameter (volumetric water content, oxygen level,
ORP, and temperature) was monitored throughout each experimental stage. In
addition to soil parameter testing, soil column influent and Ieachate were tested
for COD, manganese and iron content levels.

Section 3.1 is an overview of the performance of each sensor over the
entire experiment. Thereafter, each research stage is discussed in sections 3.2 —

3.5.

3.1 Individual Sensor Evaluation for All Stages

The following sub-sections describe changes observed in the sensor over
the entire time span of the experiment. The column sensor readings were
averaged as shown in the table 3-1 below. Averaged soil columns were

replicates of each organic loading and nutrient concentration.

35

Table 3-1. Sample and Condition Summary

 

 

 

 

 

. Nutrient Soil Columns

Stage BOD Loading Concentration Averaged
0 Ibs/ac/day 0% 1 & 8
1 0 lbs/ac/day 0% 2' 81 7
0 lbs/ac/day 0% 3 & 6
0 lbs/ac/day 0 % 4 & 5
65 lbs/ac/day 25% 1 & 8
2 65 lbs/ac/day 0% 2 & 7
65 Ibs/ac/day 50% 3 & 6
65 lbs/ac/day 100% 4 81 5
65 lbs/ac/day 25% 1 & 8
3 65 lbs/ac/day 0% 2 & 7
65 Ibs/ac/day 50% 3 & 6
500 Ibs/ac/day 100% 4 & 5
65 Ibs/ac/day 0% 2 & 7

4 500 lbs/ac/day 100% 4, 5 & 6*

1000 lbs/ac/day 100% 1, 3 & 8

 

 

 

 

 

* Column 6 was not exposed to 500/lbs/ac/day until stage 4 (approximately 30
days after columns 4 &5). The sensor readings were adjusted to the same start
date as columns 4 & 5 in order to average values.

 

3.1.1 Soil Water Content
Figure 3-1 is a historical snap shot of all the volumetric water readings
collected during the experiment based on Stage 4 loadings. When the columns
were flooded during stage 1, all depth C sensors displayed an increase from
approximately 0.12 to 0.28 volumetric water content. The soil moisture content
levels showed little variation through out stage 2 for all depths and loading

conditions.

36

 

 

Averaged VWC Content Value:
0.70 -__-. -r - —- ——e 2..

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stage 1 Stage 2 Stage 3 .\
No BOD LOADING 65 lbs BOD/ac/day , \
0.60 ,W,. —— 7 ’ l
0.50
0.40 - -
‘2’
0.30 ,
0.20 ~ ,, , r 7 ~ w r — ”i
0.10 ,,, , ,
0.00 Y ; ‘ ‘ , . .
0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240
Days at Operation
_ - - - Contra- DepthA—m - - - Control - Depth 8 — :_- - Control- Depth C
—— 1000 Ibs/ac/day - Depth A —1000 lbs/ac/day— Depth 8 ------1000 Ibs/ac/day- Depth C
- ~j:500 lbs/aflay- 09991" , 75— 500ilbs/ac/daL Depthg —j)0 lbs/flday- Depth C

 

 

Figure 3-1. All Stages - Volumetric Water Content

In stage 3, the organic load of 500 lbs BOD/ac/day was introduced. This
created in increase in VWC for that particular loading at depths A, B and C.
Depth C’s volumetric water content increased past the upper limit of sand
saturation values, 0.42. Higher than expected saturation values are can be
caused by high organic matter presence and increased electrical conductivity,
which cause a delay in the return of the pulse signal. Similarly, in stage 4 when
the organic load of 1000 lbs BOD/ac/day was introduced, the soil moisture
content for this condition increases at all depths at a faster rate than the 500 lbs

BOD/ac/day trend.

37

For multivariate statistical analysis, moisture content was treated as the
response variable to the explanatory variables time, depth, hydraulic loading,
BOD loading and nutrient. Statistical Analysis Software (SAS v 9.1) was used for
this analysis and yielded results shown in Table 3-2. In this statistical evaluation,
the numerical and denominator degrees of freedom are used to determine a
critical F-value. The P-value is calculated by comparing the calculated F-value to
the critical F-value; if significantly higher, than the p-value is less than 0.05. The
test results determined stage, depth, hydraulic loading, BOD loading and nutrient
concentration are significant in measuring soil moisture changes, since all the P-
values are below 0.05.

The pair wise comparison test was used to compare stages and depths,
shown in Table 3-3. In this test, the standard error between both values is used
in conjunction with the degrees of freedom to determine a critical t-value. The
absolute value of the calculated t-value is compared to the critical t-value; the
comparison provides the listed p-value. All P-values are below 0.05 and show
that moisture content is significantly different between depths A, B and C as well

as between stages 1, 2, 3 and 4.

38

Table 3-2. Volumetric Water Content Statistical Analysis Summary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Effect Numerical Denominator Calculated P- Value
Degrees of Degrees of F- Value (Critical Limit
Freedom Freedom (1 = 0.05)
Time 3 21 21.39 <.0001
Depth 2 14 5676.1 0 <.0001
Hydraulic 1 5160 17.27 <.0001
Loading
BOD Loadigg 1 5160 481.40 <.0001
Nutrient 1 5160 15.34 <.0001
Concentration
BOD & Depth 2 5160 1068.09 <.0001
Interaction
Table 3-3. Depth and Stage Pair Comparison for VWC
Effect Depth I Depth I Standard Degrees Calculated P- value
Stage Stage Error of t-value
Freedom
(DF)
Depth A B 0.001458 14 -3.97 0.0014
Depth A C 0.001458 14 -129.72 <.0001
Depth B C 0.001458 14 -125.75 <.0001
Stage 1 2 0.002265 21 -4.25 0.0004
Stage 1 3 0.002379 21 -6.70 <.0001
Stage 1 4 0.003412 21 -7.29 <.0001
Stage_ 2 3 0.001775 21 -3.56 0.0018
Stage 2 4 0.002863 21 -5.33 <.0001
Stage 3 4 0.002733 21 -3.27 0.0037

 

 

 

 

 

 

 

During column deconstruction, sand samples were collected at depths A,

B and C. An additional sample was taken from the very bottom (VB) of each

column. Wet and dry sample weights were used to calculate water content,

sample calculation shown below. These values were compared to the final VWC

sensor reading, table 3-4. The sensor readings do not match calculated water

content values. The sensors use a generalized quadratic equation to calculate

39

 

soil moisture content. The quadratic equation can be individualized to a particular

soil type; procedures are dictated in the manual.

Water Content =

WC (for original sand) =

Wet weight — Dry weight

 

Dry weight — Container weight

47.2889 - 46.1906 = 0.0245

 

46.1906 — 1.3269

Table 3-4. Water Content calculations after Column Deconstruction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calculated Final
Depth Water Sensor %
Column BOD Loading Label Content Readig Difference
Original
sand None - 0.02448 - -
A 0.08567 0.14260 49.9%
1000 8 0.07657 0.14027 58.8%
1 LBS lac / d ay Veg 0.17260 0.67193 118.2%
Bottom 0.22401 n/a -
A 0.09033 0.10879 18.5%
B 0.10389 0.13093 23.0%
5 500 LBS/ac/day C 0.22670 0.34586 41.6%
Very
Bottom 0.19722 n/a -
A 0.08037 0.09055 1 1.9%
8 0.10305 0.08400 20.4%
Control - 65
7 LBS / a c / d ay Veg 0.23788 0.28500 18.0%
Bottom 0.22240 n/a -
3.1.2 Oxygen Sensor

 

Oxygen level for all stages is plotted in Figure 32 Through out stages 1
and 2, oxygen level for depths A and B hovered near atmospheric levels. The

level at depth C decreased during the first stage. This is attributed to column 4,

4O

depth C, oxygen levels decreased after the column was flooded and the others
were not. This sensor never returned to atmospheric conditions.

In Stage 3, depth A, B and C oxygen sensors for the 500 lbs BOD load
began to decrease meanwhile control conditions remained near atmospheric
levels. At the introduction of 1000 lbs BOD/ac/day, oxygen levels at all depths
decreased at a faster rate to 15% oxygen than the 500 lbs organic loading. The
control conditions, 65 lbs BOD/ac/day remained near atmospheric through out

the experiment.

 

       

Averaged Oxygen Values
25 —— #~ —— ——~-——i — — —7~~ — 1
Stage 1 Stage 2
20 L‘I‘A'A‘;“_A"Zr“t-A-.-.n.~LA_LAL-A-L;Ac n.1~.:u)‘.2 .“.‘.r . |
v W W V- W -v~*T/~‘ ' v “""‘

 

W\

10 . €
500 lbs BDD/ac/day

  

Oxygen (%)

 

 

 

 

 

 

0 10 20 30 4O 50 60 7O 80 90 100110120130140150160170180190200 210 220 230 240

Days of Operation
*- - Tczonfiol TDepTh A -2 - 1 -Control - Esprit; 7 T - - team L :36ch
-— 500 - Depth A ——500 - Depth B -—500 - Depth C
—L009 39pm , ,—1009 gems ,—1000 - Depth 6 W

 

 

 

Figure 3-2. All Stages - Oxygen Level

The statistical analysis for oxygen level was treated in the same manner
as moisture content. Oxygen level acted as the response variable to the

explanatory variables stage, depth, hydraulic loading, BOD loading and nutrient

41

concentrations. The results from SAS v 9.1 are displayed in Table 3-5. Time,

depth, hydraulic loading, BOD loading and nutrient concentration were significant

in measuring oxygen level changes, since all the P-values are below 0.05.

Difference of least square means was also tested on oxygen level data;

results are shown in Table 3-6. The P-values, determined from the pair-wise

comparison, show that oxygen level was not significantly different between

depths A and B and stages 1 and 2.

Table 3-5. Oxygen Level Statistical Analysis Summary

 

 

 

 

 

 

 

 

Effect Numerical Denominator Calculated P Values
Degrees of Degrees of F- Value
Freedom Freedom

Time 3 21 31.19 <.0001
Depth 2 14 154.57 <.0001
Hydraulic 1 51 66 4.94 0.0262
LoadinL

BOD Loading 1 5166 216.09 <.0001
Nutrient 1 5166 4.14 0.0420
Concentration

BOD & Depth 2 5166 15.39 <.0001
Interaction

 

 

 

 

 

Table 3-6. Depth and Stage Pair Comparison for Oxygen

 

 

 

 

 

 

 

 

 

 

 

Effect Depth I Depth / Standard Degrees Calculated P Values
Stage Stage Error of t-value

Freedom

(0")
Depth A B 0.06645 14 0.27 0.7940
Depth A C 0.06645 14 19.81 <.0001
Depth B C 0.06645 14 19.54 <.0001
Stage 1 2 0.1038 21 -0.03 0.9740
Stage 1 3 0.1088 21 4.53 0.0002
Stage 1 4 0.1560 21 7.49 <.0001
Stgge 2 3 0.0809 21 6.13 <.0001
Stage 2 4 0.1306 21 8.97 <.0001
Stage 3 4 0.1247 21 5.41 <.0001

 

 

 

 

 

 

 

42

 

 

After column deconstruction, the removed oxygen sensors were tested in
atmospheric conditions and also in the absence of oxygen to determine if the
sensors presented a zero offset. A zero offset was determined from post-
calibration procedures and is depicted in Figure 3-3. The average offset from the
nine sensors was 0.88% oxygen. All oxygen sensor graphs were adjusted

accordingly.

 

02 Sensors in Nitrogen Chamber

.-...- Col 1A
+Col1B
+Col1C,
-----x Col 5A
+Col58
‘—l—COISC
---r-Col7A‘
+Col7B
+00”?

Oxygen Level (%)

 

 

 

Minutes

 

 

 

Figure 3-3. Oxygen Sensor Zero Off-set

3.1.3 ORP Probes
The ORP probes measurements for each column are plotted in Appendix
A. These graphs plot ORP (millivolt reading) vs. time for all four stages. All
columns at all depths show increasing linear trends, except column 7, depth c.

ORP measurements were expected to decreased when shifting towards

43

anaerobic conditions as seen in oxygen levels. Figures A-9 and A-10, located in
the appendix, compare oxygen levels to ORP linear regression. ORP regression
lines either decrease or maintain a neutral slope, contrary to decreasing oxygen
levels.

Literature findings define aerobic conditions ORP as greater than 300mV.
All the ORP measurements in this experiment began in the 50mV to 200mV
range. ORP data was collected at different times each day through out the
experiment. On occasion, it was collected twice in one day to confirm time of day
had no effect on ORP values. Frequently the influent was sprayed while
collecting ORP data; this also did not have an effect on collected ORP values.

ORP ranges are further summarized in Table 3-7, per stage and BOD loading.

Table 3-7. ORP Minimum and Maximum Values

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth BOD Loading ORP Minimum ORP Maximum
(LBS/aclday) (mV) (mV)
0 53 209
A 65 76 284
500 118 560
1000 173 309
0 33 234
B 65 60 301
500 190 515
1000 65 246
0 19 348
C 65 60 444
500 156 463
1000 126 329

 

 

 

 

 

The maximum ORP reading, 560 mV, was found at depth A and 500 lbs
BOD loading. The minimum reading was only 19 mV, found during stage 1 with

no organic loading. These measurements are incongruent with literature findings.

44

Szogi et al. (2004) measured ORP at three different soil depths 0.02 m, 0.05 m
and 0.10 meters. They observed ORP mV readings ranging from >300 mV to
below <-100 mV. It was observed that under flooded conditions, soils rapidly
became anaerobic and oxygen was depleted as reflected by the ORP readings
less than 100 mV. Hicks (2002) monitored ORP values at 1.5 m and 3.0 m
depths. Lower ORP values were observed at the lower depth electrodes. Redox
values observed in the 1.5 m depth ranged between 500 and 700 mV. At the 3 m
depth varied between 200 and 300 mV. Both sources used self-made ORP
probes with an external salt bridge reference, unlike in this experiment where the
reference point was within the probe.

Since the ORP values did not match those as expected, Hanna
Instruments lab technicians were consulted on their protocol to measure soil
ORP and to determine possible erroneous readings. Erroneous readings can be
caused by scratches on the probe surface, debris clogging the electrode or poor
contact.

During column deconstruction, all probes were visually inspected for
clogging and scratches and appeared to be clean and scratch free. The ORP
probe located in column 5, depth C, did not have any sand touching the surface
and appeared extremely clean.

Each ORP probe under went post calibration procedures to prove probe
functionality. Each probe was testing in standardized ORP solution and in

anaerobic digester sludge.

45

Table 3-8 displays the ORP readings from the standardized solution and
Table 3-9 displays the readings from anaerobic sludge. The standardize OFlP
solution provides a :10 mV tolerance, of which all tested probes were slightly out
of range. Column 1 depth C was the most deviated.

A negative ORP reading was detected by all probes in the anaerobic
digester sludge. The portable ORP sensor used for the influent and effluent
testing was also dipped into the anaerobic sludge as a comparison point. All
Hanna Instrument OFlP probes were within 44mV to 85mV of the portable sensor.
The Hanna Instrument ORP probes proved to be operational; however, not in soil
applications. Consequently data from ORP readings were found to be of minimal

use.

Table 38 Post Calibration, ORP Sensor Reading in Standardized ORP Solution

 

 

 

 

 

 

Std
ORP
soln Standard % over
Depth temp ORP ORP Standard
Column BOD Loading (°C) readout (2:10 mlfl ORP value

A 1 4.1 234 245.17 0.49%

1 1 000 LBS/ac/day B 1 4.8 232 244.26 0.95%
C 14.6 221 244.52 5.81%

A 1 3.3 234 246.21 0.92%

5 500 LBS/ac/day B 14.7 234 244.39 0.16%
C 14.8 234 244.26 0.11%

Control _ 65 A 16.3 232 242.31 0.13%

7 LBS /a c / d ay 8 14.2 232 245.04 1.27%
C 13.8 232 245.56 1 .49%

 

 

 

 

 

 

46

 

Table 39 Post Calibration, ORP Sensor Reading in Anaerobic Digester Sludge

 

 

 

 

 

 

 

 

 

ORP Readout
Column BOD Loading (mV)
-394
1 1000 LBS/ac/day -387
-428
-410
5 500 LBS/ac/day -405
-410
7 Control - 65 :33;
LBS/ac/day 401
Portable ORP Sensor -343

 

3.1.4 Soil Temperature
Figure 3-4 shows temperatures recorded through out the experiment for

all columns and all depths, a total of 24 sensors. There was little variation among
sensors during stages 1 and 2. A wider temperature spread was observed
towards the end of stage 3 and through out stage 4. The temperature never
reached extreme conditions and only varied in the range of 135°C to 26°C.
Temperatures decreased accordingly to ambient temperatures however, the soil
columns were located indoors and were not exposed to the Michigan’s winter

temperatures.

47

 

Historical Temperatures

23 ~——— g — __,__, «—

 

 

 

 

 

 

 

 

 

26 . i .. i. .7 _ h. 7 . ,7 ,,,7 ,__ 7 2%...
24 — —
’e‘
2
5 22 -» , ~ r l
320-- - - e - e e e
is"
:18 J» i 7 7 A 7 ‘ i All ‘7 ~ i
2 . . ._ y) l
i 16 as 7 I & ./I a- a _,_ ., '/_ W 7
, . . , a- J
E /J -” r -
'- ) ‘u . 7 I I,
14 , , - ,, ,, ,, ,.‘ —_~ ,, _, , ,-
12 , , a,
l

o 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 192 204 216 228 240
DaysofOperatlon

 

 

Figure 3-4. All Stages — Temperature, all columns and all depths

Temperature was statistically tested in the same manner as moisture
content and oxygen level using SAS v9.1. The fixed effects results are displayed
in Table 3-10 and the pair comparison chart in Table 3-11. Temperature was
affected by time and hydraulic loading, but it was not affected by depth, BOD
loading or nutrient concentration. The pair wise comparison showed no
significant difference between depths A, B and C. Among the stages there was a

significant difference between stages 2 and 3.

48

 

Table 3-10. Temperature Statistical Analysis Summary

 

 

 

 

 

 

 

 

Effect Numerical Denominator Calculated P-Value
Degrees of Degrees of F- Value
Freedom Freedom

Time 3 21 1904.64 <.0001
Depth 2 14 3.19 0.0720
Hydraulic 1 5166 39.73 <.0001
Loading
BOD Loading 1 5166 1.11 0.2929
Nutrient 1 5166 0.02 0.8828
Concentration
BOD & Depth 2 5166 1.87 0.1540
Interaction

 

 

 

 

 

Table 3-11. Depth and Stage Pair Comparison for Temperature

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Effect Depth / Depth l Standard Degrees Calculated P-value
Stage Stage Error of t-value
Freedom
lDF)
Depth A B 0.06221 14 0.27 0.1 666
Depth A C 0.06221 14 19.81 0.0950
Depth B C 0.06221 14 1 9.54 0.0058
Stage 1 2 0.08779 21 -0.03 <.0001
Stage 1 3 0.09543 21 4.53 <.0001
Stgge 1 4 0.1393 21 7.49 <.0001
Stage 2 3 0.07552 21 6.13 0.3705
Stage 2 4 .1219 21 8.97 <.0001
Stage 3 4 .1163 21 5.41 0.0001
3.2 Stage 1

In the following sections, each experimental stage will be discussed.

Generally replicate averages are represented in the plots, unless replicates were

substantially different, then it was segregated.

49

 

 

The first stage in this experiment did not apply any organic loading to the
columns; only dechlorinated tap water. This experimental stage was subdivided
into three separate phases. During the first phase, stage 1a, 2 L of water were
applied per day to each column in one dose. In order to provoke changes in the
sensors, hydraulic loading was varied in the second phase, 1b. Four hydraulic
loading conditions were tested each with duplicate conditions: 0, 1, 2 and 4 L/day
applied in a single dose. During this phase all columns were flooded with
approximately 33 L. In the final phase, 10, each column was assigned an
individual pump that was connected to a timer to spray 600mL every 6 hours, for

a total hydraulic load of 2.4 L/ac/day.

3.2.1 Sensor Readings

Volumetric water content and oxygen level for stage one are shown in
figures 3-5 and 3-6, respectively. Only depth A sensors during the first phase of
stage 1, showed a slight decrease on day 13 and 21. The columns did not
receive the hydraulic loading during the weekends, which corresponds to these
dates.

In the second phase of Stage 1, depth A and B sensors showed response
to the varying hydraulic loadings. The O L/day application dropped below 0.05
VWC. The other hydraulic loading conditions only reached a minimum of 0.05
and a maximum of 0.07. Depth C sensors only varied when the columns were
flooded, where every depth C sensor increased by 50% volumetric water content.
For the remainder of Stage 1 there were minimal changes and depth C soil

moisture hovered around 0.27 VWC.

50

 

Stage 1 - Volumetric Water Content

0'30 7 Sta 10 7 7 7» ‘
Stage 1A Stage 18 . 2 43?“ . — 0L - Depth A
2L/day Varying H.Load ‘ ‘ . ' y

97:: ____ :.- -._-.~ _- ......... —0L-Depth B‘

    

—0L - Depth c

‘—-—r1L-DepthA

.0
to
o

—-—-1L-Deptth

Column Flooding

MW --—1L-DepthC

l
_ ‘ ---2L-DepthA
-FJA.;Q4.‘.-—p.-_--._-47

 

- - -2L-DepthB,
l
-DepthC

0.10 4

 

‘5
fl
8
5
5 0.15
§

- Depth A

- Depth B

 

- Depth 0‘

 

 

 

0.00

 

10131619222528313437404346495255586164677073
Days of Operation

 

 

 

Figure 3-5. Stage 1 - Volumetric Water Content

Figure 3-5 plots the replicate averages. Column 4 was flooded 7 days
prior to the other seven columns; this corresponds to the 2 increases shown for
depth C in stage 18. The first increase did not reach the maximum VWC (0.28)
reached during flooding. An individual plot for column’s 4 and 5 volumetric water
content sensors is below, Figure 3-6. Column 4 reached higher saturation values

than column 5.

51

 

 

Volumetric Water Content

0.30

.0
M
at

'8

.0
_.
at

.0
_.
o

0.05

0.007 ‘
10131619222528313437404346495255586164677073

Stage 1 - VWC, Columna 4 a 5

 

Stage 1A
2L/day

 

 

   

Stage 10
2.4L/day‘ )fi_

_ 2 __________ —c4
......... _C4
— 704
.— -«--cs
- -~cs
.. _ (25

 

ffi~u‘~-~‘~.~I-l-I—p——H-H

 

 

Days of Operation

43th X
- Depth B ‘
- Depth C
- Depth A ‘
- Depth 8
- 06mg l

 

Figure 3-6. Stage 1- VWC for Columns 4 and 5 during Stage 1

Oxygen levels at depths A and B did not fluctuate with the various

hydraulic loads as shown in Figure 3-7. Depth C had 2 decreases in two test

columns. Individual oxygen responses are plotted for these columns in Figure 3-8

because of the differences in values between the replicates. The cause of this

difference is not known and substantial variations between other replicates and

parameters were not seen. Oxygen level in column 4, depth C reduced from

approximately 20% to 3.8% oxygen over the next 28 days, and never returned to

atmospheric levels. Column 7 depth C decreased 4% after flooding.

52

 

 

 

Oxygen Level (%)

25.0

20.0

15.0

10.0 '

5.0

0.0

 

Stage 1A
2L/day

 

 

 

‘ ‘~*&:{r

 

—_ .-—-__
.-.-—-_1

W

 

 

Stage 18

Varying H.Load

 

 

 

*:';—..:;-"‘—~’—‘-r\_a~ .a-~—

\
'[Column Flooding]

 

 

 

 

Stage 10 '
2.4L/day'

 

 

—‘

b_.-

 

 

 

 

 

¢

10131619222528313437404346495

i T ‘ i ;

Days of Operation

2 55 58 6164 67 70 73

—‘ 0L - Depth A

-——0L-Depth B,
—— OL-DepthC
--—1L-DepthA
---1L-DepthB

‘———1L-DepthC‘
‘- - -2L-DepthA

- - -2L-DepthB
- - -2L-DepthC

‘—4L - Depth A‘

-——4L - Depth 8
—4L - Depth C

 

Figure 3-7. Stage 1 - Oxygen Level

53

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stage 1 - Oxygen Level, Columne 4 & 7
25.0 < '
Stage 1A Stage 18
2L/day 4L/day
20.0 figfififl 4' x
m ‘ ' ’
" ‘ """"" H-fi .4 nnnnn 4' K. “-H
l
A t ‘ fl * x
95150 I ”W; . C4-DepthA
? 't i----C4-DepthB
a ‘.\@umn Floodingfl _ ' T ' C4 ' Depth C
8 ‘- ‘ —---—- C7 - Depth At
t
g 10'0 77 7 7 '\ ‘——C7-DepthB
'\ — C7 - Depth C
.\ --~-..-\ _ -_ a fi.
5.0 i 777‘ '77 7 7 7W“-\V<1 -"/" fi' if ’77 ’7
0.0 - ' ‘ : - ' ~—.#
10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73
Days of Operation
Figure 3-8. Stage 1 - Oxygen Level for Columns 4 and 7
3.2.2 Leachate Analysis

The influent, dechlorinated tap water and column Ieachate samples were
collected during stage 1 to measure manganese and iron content while no
organic wastewater or nutrients were applied. The tap water at Michigan State
University has varying iron content; at times the water wasn’t completely clear
and had a red tint. Effluent manganese content tested below 0.05 ppm from all
columns during stage 1. Iron levels were also below 0.05 ppm and leveled off to

0 ppm near the end of the stage 1 in all columns, Figure 3-9.

54

 

 

Iln (ppm)

(15

Stage 1 - Leachate Mn content

 

0345 '

0:4

 

 

Stage 1A
2Uday

 

 

 

 

 

Stage 18
Varying H.Load

 

 

 

25 28 31 34

 

Stage 10
2.4L/day

 

 

 

 

Ch
I.
I.

37 40 43 46 49 52 55 58 61 64 67 70

Days of Operation

 

 

73

e 0 Uda_;
I 1 Uday
a 2 Uday
3 4 L/dayg

 

 

0.5 r"

 

 

0454

Stage 1A
2Uday

 

 

0,4

0,35

02

0.15

0.1

0.06

 

Stage 1 - Leachate Fe content

 

 

Stage 18
Varying H.Load

 

 

 

 

 

Stage 1C
2.4Uday'

 

 

 

>-

 

 

25 28 31 34

37 40 43 48 49 52

Days of Operation

 

-
- i

73

o 0 Uday

I 1 L/dayl

a 2 Uday
‘ . al./day]

 

Figure 3-9. Stage 1 - Leachate Manganese and Iron Content

55

 

3.3 Stage 2
In stage 2, all columns received the 65 lbs BOD/ac/day of organic loading
but nutrient concentrations were varied. The replicates were averaged and

plotted against time for all the following figures.

3.3.1 Sensor Readings
Soil moisture content had minimal variation throughout stage 2, Figure 3-
10. Depth A at 100% nutrient concentration has a notch on day 113; this
corresponds to a pump impeller malfunction. Depth C with 100% nutrient had an
increase from 0.25 VWC to 0.27VWC; this was due to an increase in one of the

replicates, column 4 depth C, which increased 0.05 VWC over the time span of

 

 

 

 

 

 

      

 

 

 

 

 

 

 

stage 2.
Stage 2 - Volumetric Water Content
0.30 . »- — . . — . , ,
Stage 1 - No organic loafl Stage 2 - 65Ibs/ac/day. varying nutnentsJ , — 25 /o N - Depth A
K:~. _ . i —25%N-DepthB
\} a I ’ \s . I _ I
, ’7'“ " ,g , ! l
0'25 ' V ' i —— 25%N - Depth C
_ i — - - 0%N - Depth A
c l
g 0’20 i - - - 0%N - Depth 8
i
5 I -——O%N-DepthC ‘
a l
f 0'15 l - - -50°/eN-DepthA
i g - - - 50%N - Depth B
:i i
g 0'10 - - - 50%N - Depth 0
, —100%N - Depth
‘ A
0'05 i —100%N - Depth
a B
i —100%N - Depth
0.00 t . . . J . ,, C
0 9 18 27 36 45 54 63 72 81 90 99 108117126135 144 153162 171

Days of Operation

 

 

 

Figure 3-10. Stage 2 — Volumetric Water Content
56

Oxygen levels also remained near atmospheric conditions with minimal
variation to the exception of column 4, depth C. Figure 3-11 does display the not
averages for depths C at 100% nutrient concentration to magnify the difference in

oxygen sensor readings. Column 4, depth C oxygen level increased 5% during

stage 2.

 

Stage 2 - Oxygen Level

25 «———- ———-————-— ——

 

 

[Stage 1 - No organic load [Stage 2 - 65Ibs/ac/day, varying nutrients}

 

7—7 25%N - Depth} ”7
. — 25%N - Depth B

25%N - Depth C

 

. ———0%N-DepthA
. — — — 0%N - Depth B

—L
01
I

 

- - - 50%N - Depth A

d
O

- - - 50%N - Depth 8

Oxygen Level (%)

I - . ---0%N-DepthC

_.-. 5 ---50%N-DepthC
. ‘ , —-100%N - Depth A
,, ‘ , ‘ . a _ 7. , ‘ —100°/oN-Depth B

. ' ‘ ' 1000/0N - C4 Depth
C

 

 

 

—— 100%N - CS Depth
0 ' * C

0 12 24 36 48 60 72 84 96 108120132144156168
Days of Operation

 

 

 

 

Figure 3-11. Stage 2 — Oxygen Level

3.3.2 Leachate Analysis

Influent and Ieachate was tested for COD and manganese and iron

content. COD was reduced by at least 90% from the influent, Figure 3-12, for all

nutrient conditions tested.

57

 

 

 

 

 

 

Stage 2 - COD Concentrations
600 — ~ - —-——— _— 1
l
l
400 /\/‘\\ i
A E + Influent
é ! + 0% Nutrient
. 300 h 1 +25% Nutrient
g l 50% Nutrient
i —.«—— 100% Nutrient
200 i A l
l
I
100 — - —— l
K ..-"~‘ >7 -» 1
0 fW-N-Vwk‘ l
81 90 99 108 117 126 135 144 153 162
Days of Operation

 

 

Figure 3-12. Stage 2 — Leachate COD Concentrations

Under the aerobic condition assumption, manganese and iron content
were predicted to be below 0.05 ppm. Figure 3-13 plots the manganese and iron
content over time for all four varying nutrient conditions. Manganese content has
a spike around 10/13 in all four nutrient variables, which could be attributed to the
water source variability and not metal reduction processes. All nutrient conditions
stabilized to below 0.05 manganese ppm and below 0.10 iron ppm. These
manganese and iron content levels are not indicative of metal mobilization or

anaerobic reduction reactions.

58

 

 

Mn (PPM)

 

1 if, ,. 7 ,
Stage 1 - No organic loading

Stage 2 - Leachate Mn content

Stage 2 - 65 lbs BOD/ac/day

 

 

 

 

 

" .7 ssjfie Bog/709a N 5465 lbs BODL2755/eiiif' resilie'BpBZscg [17+ s00 lbs BOD/ 100% N

 

 

F0 (ppm)

 

22 34 46

1 —.__—s _—_
‘ Stage 1 - No organic loading

Stage 2 - Leachate Fe content

 

‘ Stage 2 - 65 lbs BOD/ac/day

 

58 7o 82 94
Days of Operation

 

nEtbeeofilo°A N +65 Ibejagp @537. N - f651bs§05l5§°k~ N 475on BOD / 1607.377:

 

59

Figure 3-13. Stage 2, Leachate Manganese and Iron Content

 

3.4 Stage 3

Only one modification occurred during stage 3. The 65 lbs BOD/ac/day
with 100% nutrient condition was changed to 500 lbs BOD/ac/day with 100%
nutrient concentration. The remaining three testing conditions remained at 65 lbs
BOD/ac/day with a varied nutrient concentration.

During this stage the soil columns exposed to the increased organic
loading developed a fungal growth at the top of each soil column as seen in

Figure 3-14. At times the odor emitted from these columns could be linked to an

alcohol, manure-like and sulfur smell.

 

Figure 3-14. Fungal Growth on Top Surface of Column 4

60

3.4.1 Sensor Readings
The sensors showed no significant variations at the 65 lbs BOD with

varying nutrient conditions from stage 2 readings. However figure 3-15 shows for
the 500 lbs BOD loading, volumetric water content increased at depths A, B and
C approximately four days after the start of stage 3. Water content increased with
depth, where depth A values are the lowest and depth C values are the highest.
Depth C increased to levels beyond the saturation predicted saturation range
0.30-0.42. The greater than expected reading occurs when high organic matter,

high electrical conductivity and high salt content are present.

 

Stage 3 - Volumetric Water Content

0.60 ~

* L 25%N . DeDthA

25%N - Depth 8

 

0.50 ,7
—— 25%N - Depth C ‘

'---0%N-DepthA

'8
l
l
l
l
l

 

-— -0%N - Depth 3

i-—-0%N-DepthC .
,, , ,, , l - - -50%N-DepthA
W“'“"‘""’"‘-":_;;_:_-_,-__'..‘~-_'__::::;/~'—L: ‘

 

 

 

 

Volumetric Water Content
0
8

 

 

 

 

 

 

Leek-LELL- - - ~ - L» l - - - 50%N - Depth B
0.20 i , , ~ l - - -50%N- Depthc
'-——5oo-DepthA
0.10 ,, a- , , , —5oo-Depthe
“V —500 - Depthc
0.00

 

 

72 80 88 96 104 112 120 128 136 144 152 160 168 176 184 192 200
DayaofOperation

 

 

 

Figure 3-15. Stage 3 — Volumetric Water Content

61

The oxygen levels remained near atmospheric at 65 lbs BOD/ac/day with
varied nutrient concentration, figure 3-16. As soil moisture content increased,
oxygen levels decreased accordingly in the 500 lbs BOD/ac/day loading
condition. Depth A and B oxygen sensors started to changed approximately one
day after initiating stage 3 and depth C started to decrease two days after the
start. Depth A had a lower oxygen level than depth B, which could be attributed
to the oxygen consumed by the fungal presence. Depth C shows the lowest

amount of oxygen which corresponds to the highest soil moisture content levels.

 

Stage 3 - Oxygen Level

25

Stage 2 Stage 3 l
E
20 '- A /‘ J \ f \ . \ I \ ,4 / J K \. I I ..4 § A ’ I -4 0 L77 7
' 29;“- {h ~‘~.—*~~-. V .. : “<1; ‘ .' "" t‘ 3'65 a :‘W: 25 W ' Depth A i
.. , - - v , ' ‘

 

25%N - Depth B
25%N - Depth C
- - - 0%N - Depth A

i — - - 0%N - Depth 8
— - -0%N - Depth C

I - - - 50%N - Depth A
¢ - - - 50%N - Depth B
i ‘ - - - 50%N - Depth C
l ———500 - Depth A ‘
5 - ~ ' , I —500 - Depth 8

l —500 - Depth 0

 

\m

    

 

 

0 ._._._-- ._ _ .
72 80 88 96 104 112 120 128 136 144 152 160 168 176 184 192 200

Days of Dwation

 

_._._._- . ._,

 

 

 

 

 

Figure 3-16. Stage 3 - Oxygen Level

3.4.2 Leachate Analysis
Approximately two weeks after increasing the organic loading, the

Ieachate changed in color. It cycled through a milky white color to a distinct, clear,

62

yellow tint. The changes occurred one week prior to manganese mobilization in
columns exposed to 500 lbs BOD/ac/day. No correlation was found to other
Ieachate parameters tested: pH, ORP, COD.

Chemical oxygen demand was reduced in all conditions (Figure 3-17).
There was a slight increase in COD content for all tested conditions on first day
of stage 3 of approximately 25mg/L; thereafter the soil columns treating 65 lbs
BOD/ac/day reduced the COD content to levels below 20 mg/L, nutrient
concentrations do not appear to have an effect. Fluctuations in COD content
could be caused by human error while calibrating pipette tips and COD blank vial
preparation. The higher organic load tested, 500 lbs BOD/ac/day, consistently
resulted in higher COD content than the 65le BOD loading condition. At times
the COD concentration was 7 times higher which, indicates soil column was not

assimilating organic waste in the same manner as the other columns.

63

 

Stage 3 - Leachate COD Content

 

100 L— —— -- - ., 7777

 

% ,, 7 7, 7, 77 7
80 L L 7 7 7
7o 7 ,7 7. . 7, ,7 77 , , ,, 7 ,7
—o— 65 lbs BOD / 25% N
60 . 7 7 7 7 7
+— 65 lbs BOD /0°/o N
50 7 7 7 7 7

65 lbs BOD / 50% N

Leachate coo (mg/L)

l
p—x— 500 lbs 800/ 100% N

l l

 

 

 

 

171 177 183 189 195
Days of Operation

 

 

 

 

Figure 3-17. Stage 3 -— Leachate COD Concentrations

As in stage 2, the 65 lbs BOD/ac/day manganese and iron concentrations
remained below 0.05 ppm.

Manganese became mobilized in the other organic loading condition
tested, 500 lbs BOD/ac/day, approximately 15 days after initiating stage 3. Figure
3-18 shows the manganese concentration increase during stage 3. The higher
manganese concentrations indicate manganese was mobilized through
anaerobic oxidation-reduction processes. VWC probes at depths A and B
showed a response to the increased organic load within a day, and depth C
sensors showed after four days from the start of stage 3. Oxygen sensors at all

depths started to decrease one day after initiating stage 3.

64

 

Stage 3 - Leachate Mn content

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stage 2 - 65 lbs BOD/ac/dm 1
0.9 L 777 L L L L 7 L L |
l
0.8 L L L L L—L L L l
l
0.7 L LL LL L L ‘
A 0.6 L L 7- L L L L 7 L 7
E
o.
3 0.5 r 7 L LL — 7 77 7 L
t:
I
0.4 7 LL 7 L
0.3 7 7 L 7 7 L
O
0.2 L L L L L L . -
O
O
01 , _____ 77. __ 7 _ 7 _ _ 7__. .7._ 7.. 77 _ ___.
0
e 0 .
0 1! Wi—LeLl—L. B—LL—fiflLflMQ—L
112 122 132 142 152 162 172 182 192
Days of Operation
.:- 656s 8075/ 0%.?! +735 tbs Bog/55% N 176% 699 / 507% “75000889917096 '3 l
Stage 3 - Leachate Fe content
1 - . L. _ __.__ . _. ____7. __ .__-__._, 77 . -.7__7_ 7 7---.77 -LLL 7 __
Stage 2 - 65 lbs Boo/ac/dafl l
0.9 L .. , L L . L L - L _.
0.8 7 L L L L
0.7 » L L L L L
0.6 L L L L L L 7 L
g .
5. 0.5 lL L L L L L L L L . i
it
0.4 L L L L
0.3 - L L L L L L L L
0.2 - LL _ _ —
0.1 — L L LL LL L LL L L 3..-
’9 .. . n .. C _ O
0 LAeL-JdL-l—JM . 37.7.7750 nLLfiEL—LL—R—Ll f * INK _
112 122 132 142 152 162 172 182 192
Days of Operation

L» 65 lbs BOD [0% N 465 lbs 8ch (25% N .: 65le 80D? 50% N7 .7 750077le BOD7100% N

 

Figure 3-18. Stage 3 - Leachate Manganese and Iron Leachate Content

65

 

3.5 Stage 4

For the results evaluation in stage 4, the columns were grouped by the
varied organic loading. Three organic loadings were tested: 65 lbs BOD/ac/day
with 0% nutrient concentration (designated as the control), 500 lbs BOD/ac/day
with 100% nutrient concentration and 1000 lbs BOD/ac/day at 100% nutrient
concentration. Triplicates existed for the higher loading conditions and there were
duplicates of the control conditions. In order to average triplicates, the start date
for the third replicate of 500 lbs/ac/day was adjusted to the same start date as
the other two soil columns in stage 3. Only average readings have been plotted.

Fungal growth surfaced much quicker in this stage and covered the top
surface area of the remaining soil columns except the control columns. Columns
4 and 5 started to mix black microorganism growth with the present fungi. Near
the end of the experiment, infiltration rates on columns 4 and 5 were much

slower and puddles of water were formed atop.

66

 

Figure 3-19. Column 1 Top Surface, end of Stage 4

3.5.1 Sensor Readings

Figure 3-20 is the graphical representation for volumetric water content for
stage 4. Control conditions remained constant throughout the experimental
stages 2, 3 and 4.

Soil moisture content reached maximum levels during stage 3 for the 500
lbs BOD/ac/day loading condition. For the duration of stage 4, depths A and B
remained at 0.12 VWC and 0.15 VWC respectively. Depth C had minor
fluctuations yet remained above 0.50 VWC.

For the 1000 lbs BOD/ac/day condition, volumetric water content for all
depths increased at a faster rate than 500 lbs BOD/ac/day. Depths A and B
reached 0.15 VWC two days after the start of stage 4 and Depth C passed

beyond saturation to readings above 0.60 VWC four days after the start of stage

67

4. At the beginning of stage 4, depth A shows higher water content values than

depth B however, both depths leveled at approximately 0.15 VWC.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stage 4 - Volumetric Water Content
0'70 Stage 2 — Stage 3 ‘ ___ "WWW— -_ _____-_ l
Sta e4 !
—l ,. ;
0.60 «L LL- LLL LLL ,..2 .""'fi l
. . - — - 65 - D th A
0.50 i l i . 1 6p
I : ---65-DepthB
l
. l -—-65-DepthC
5 0.40 L L f - 'f —500-DepthA
.' |
i , g : -—500 - Depth B
i 0.30 LIL i -—500-DepthC
g ”ML-u..- a: ___________ i - - '1000-DepthA,
a Mo
3 5 ---1000-DepthB
> 0.20 , A 22 7 ;.
’.~ } ---1()OO-DepthC1
s ’ ‘ . . . L LL v v-
_ l ‘ I I‘. ‘- ~ .’ i
. .. ,, . .7- W l
0'10 T: : . - . : TI r;;§;;;;;=::Ff;?fi)1§:Ld=——==a-====::l
0.00 l
140 150 160 170 180 190 200 210 220
Days of Operation

 

 

 

Figure 3-20. Stage 4 — Volumetric Water Content

Figure 3-21 shows oxygen levels continued to decline for 500 lbs
BOD/ac/day condition in stage 4. The curve for 500 lbs BOD/ac/day at depth C
differs from that shown in Figure 3-16, Stage 3 - Oxygen Level, due to the
replicate averages as described in table 3-1. Depth B oxygen level remained
higher than depths A and C, most likely due to the added oxygen consumption
from the fungi. Oxygen was consumed at a faster rate at the 1000 lbs
BOD/ac/day condition, reaching 15% oxygen level by all depths within four days.
Although the oxygen sensors showed a decline in oxygen within one day of

applying 1000 lbs/ac/day.

68

 

Stage 4 - Oxygen Level

 

25 — _- LL- -_-

Stage 2 Stage 3| Stage 4 | w

 

20

  
  

"”\'~ p\”’ —‘,It=!‘
" -— \’ \—\’-‘

l

t

l

l. _ -_
l—L—ss-oepthA
it
i—--65-DepthB
|

gL—Les-oeptho

d
01
L
T

fill—soo-DepthA

l
{ —-500-DepthB ,
l
l -—500-DepthC

Oxygen Level (%)
‘o‘

5.. - -1000-DepthA
’- - -1000-DepthB
,, -2 _. , .7 - - -1000-DepthC

 

 

 

 

140 150 160 170 180 190 200 210 220
Days of Operation

 

 

 

Figure 3—21. Stage 4 — Oxygen Level

Soil moisture content and oxygen levels were compared per organic
loading condition in the following graphs for stages 2, 3 and 4. At 65 lbs
BOD/ac/day with 0% nutrients, oxygen level remained near atmospheric levels,
Figure 3—22. This indicated oxygen was not limited at this organic loading
promoting aerobic microorganism growth. Volumetric water content also
remained constant and below saturation, maximizing the pore space for oxygen

presence.

69

 

4.0

0.0

 

Soil Moisture Content ve. Oxygen Level
65 lbs BODIac/day

 

 

 

P 31 @L-L-LLLLELLLLL
l
" T7 L ~ _ If ‘7“ T
L_[Column FloodingJ
f ; __ 7_ 2 g
_ - - J
.-L..L::.;....L..L:L.LL_-.~L.;.~.L.L_....._.,.
a'r '. . .
___. 4.] , , f a 7

 

 

 

 

 

 

 

8 20 32 44 56 68 80 92104116128140152164176188200212224

Daye of Operation

0.30

0.25

0.20

Ar 0.15

> 0.10

2 0.05

0.00

7 —--DepthA(02)
Depth 8 (02)
Depth C(02)

— - DepthA(VWC) j
— - Depth B (VWC)
— - DepthC(VWC) ‘

 

 

Volumetric Water Content

 

Figure 3-22. 65 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Level

As seen in Figures 3-23 and 3-24, volumetric water content increased as

oxygen levels decreased for 500 and 1000 lbs BOD/ ac/day treatments, the later

occurring at faster rates. The decrease in oxygen indicates movement towards

anaerobic conditions.

70

 

 

 

DeTJth A (027

 

Soil Moieture Content ve. Oxygen Level

 

 

 

 

 

 

 

 

 

 

500 lbs eon/way 1 — 069‘“ B (02)
Depth C(02)
24.0 L 0.50 . ' - - DepthA(vwc)‘
- - - Depth B(VWC)
' :..P°P"19-<_VWCL
20.0 L 0.50
E
16.0 0.40 g
1‘. 8
1‘ a
3 12.0 030 g
C 0
8. E
g E
3.0 0.20 g
>
4.0 0.10
0.0 0.00

8 20 32 44 56 68 80 92104116128140152164176188200212224
DayeotOperation

 

Figure 3-23. 500 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Level

71

 

 

 

 

 

 

 

 

 

 

Soil Moisture Content ve. Oxygen Level I Depth A (02)
1000 lbs BODIacIday — Depth 8 (02)
Depth C(02)
24 713*#7 is" -—-7El———_~-—-------—‘~§I——~—-~E[- ------ 0.70 - - - DepthA(VWC) 3
,“ - - - Depth B (VWC)
.' 0.60 L PEPEEWWQ
20 ,,L L LLL - L . .
WW“ \VNN ‘~ ~W n
.' 0.50 g
16 - LL LL LL LL . LL .
s “v 5
g ' 040 g
c 12 LL LL LL - L L,' g
8. ,' 0.30 ‘3
s .. . g
o I ................ P ------ 3
8 i * " a
. 0.20 >
O - _ . .' I’L‘I‘:
4 7 7 7 7 7 '3' 7 0.10
‘,""4- _0 -,-.-_-_-_:;:=:=:::::::::r ''''''''''''''
0 L L . L L LL L L 0.00
8 20 32 44 56 68 80 92 104116128140152 164 176 188 200 212224
DayeofOperatlon

 

 

 

Figure 3-24. 1000 lbs BOD/ac/day - Volumetric Water Content vs. Oxygen Level

3.5.2 Leachate Analysis

As previously seen in stage 3, the Ieachate from the elevated BOD
conditions changed colors in the same fashion from milky white to a distinct,
clear yellow tint. The Ieachate color changes occurred within a week of stage 4
start time; stage 3 color changes occurred two weeks after it was initiated. The
control Ieachate remained crystal clear throughout the entire experiment. There
was no correlation of Ieachate color change to the other recorded Ieachate
measurements of COD, pH, iron and manganese content.

The control conditions continued to be reduced to the lowest COD

concentrations below 10mg/L. The Ieachate COD concentration levels tripled at

72

500 lbs BOD/ac/day and quintupled at 1000 lbs BOD/ac/day from the control

values as seen in Figure 3-25.

 

Stage 4 - Leachate COD content

 

 

 

 

 

 

 

250 '-————— ~ - - —-—--LLL ._ .___.L_LL..]
Stage 4| 1
200 L L L - ‘
A 150 —---— —
é ‘ + 65 lbs BOD
v ‘—x— 500 lbs BOD ;
§ 54—1096 lbs BOD
100 LL
50 L L L L LL L L .L L L
7|\‘____‘_________.L—————-X\
\‘:/

 

195 199 203 207 211 215 219 223
Days of Operation

 

 

 

Figure 3-25. Stage 4 - Leachate COD levels

The soil columns with 500 lbs/ac/day organic loading continued to
mobilize manganese in stage 4, Figure 3-26. Iron concentrations are higher than
those in the control columns, approximately double the values.

Manganese was also mobilized at the higher organic load, 1000
lbs/ac/day approximately 17 days after initiating stage 4. Its maximum peak
appears at day 222, which corresponds to the same date as iron starts to
increase in the Ieachate. Both are good indicators that some anaerobic oxidation-

reduction processes are occurring within the soil column.

73

 

Mn (ppm)

 

Stage 4 - Leachate Mn content

 

 

 

 

 

 

 

 

 

 

194 198 202 206 210 214 218 222 226 230
Days of Operation
u g lbs 600 :SOOibs 606 {10001785 BOD
Stage 4 - Leachate Fe content
1.2 - . L L
‘ Stage 4|
1.1 LL L L L L LL L L
1 L L A

0.9 — — — — —

0.8 LL L L L
A 0.7 L L L L L L
E
E . -
.2

 

g t
‘-
224 230

(L3— 65 165780;) fsooilbsieoo #71000 lbs BOD

 

Figure 3-26. Stage 4 - Leachate Manganese and Iron Content

74

 

During stages 3 and 4, VWC sensors showed a change in response to the higher
organic loading application within four days. The oxygen sensors showed a
change in oxygen level within a day of higher organic loading application. The
changes detected by these two sensors predicted manganese mobilization,
which occurred approximately ten days after a substantial environmental change

was measured by either sensor.

75

Chapter 4 Conclusions and Recommendations

4.1 Conclusions

The functionality of all the sensors was proven in this project; however, the
ORP probe cannot be used in-situ soil environment testing. The remaining three
sensors are applicable for in-situ soil monitoring. Even small soil moisture
content changes were measured by the water content reflectometers by varying
hydraulic loading and BOD loading. Oxygen sensors detected changes in oxygen
level caused by changes in soil moisture content. Soil temperature was tracked
with minimal sensor to sensor variability.

Sensor readings also indicated soil environments can vary by depth.
Sensors located closest to the surface, depths A and B, reflect more aerobic
favorable conditions, meanwhile the deepest, depth C, sensors reached soil
saturation and oxygen limiting conditions.

Microbial oxidation-reduction processes can be characterized by
monitoring manganese and iron content in Ieachate. Manganese was mobilized
in this study at high organic loading applications. Manganese mobilization was
predicted in this laboratory-scale study by the measured sensor changes.
Specifically, there was approximately a 10 day delay after VWC and oxygen
sensors detected an environment change.

The positive results from this research project provide confidence that a
field-scale demonstration is warranted. Although the combination of moisture
content probes, oxygen level sensors and therrnistors were suitable in measuring

soil microbial environments, only two soil environmental properties are essential.

76

 

 

 

 

4'11

Soil temperature should be monitored in order to observe temperature
effects on microbial oxidation-reduction processes. The recorded temperatures in
this study remained in the range of highest microbial activity. Cold shock,
freezing and thawing cycle’s effects were not studied.

In addition to soil temperature either soil moisture content or soil oxygen
level should monitored. Volumetric water content reflected changes inversely
proportional to those seen in oxygen level presence, eliminating the need for one
sensor. The oxygen sensor detected changes in oxygen level approximately one
day sooner than the moisture content probes at depth A. In addition, the oxygen
sensor incorporates a thermistor which can also track soil temperature. The
oxygen sensor may also be incorporated into a control loop irrigation system to

manage the wastewater application rate to maximize oxygen permeability.

4.2 Recommendations

The in-situ functionality of 3 of the 4 sensors was proven in this project.
Further testing is required to determine each sensor’s sensitivity to changes in
soil microbial environments. This can be continued in a laboratory environment or
in land applied fields.

In controlled laboratory testing, BOD load can be varied in smaller
increments than those tested in this project. This may help determine a maximum,
allowable BOD load to sustain aerobic microbial population. Hydraulic loading
can also be varied to determine if multiple applications throughout the day versus

constant irrigation allows for more oxygen diffusion in soil pores.

77

Mokma’s (2006) research was unable to find congruent, recommended
BOD loading values for successful land application. However, a prescriptive
value may not be protective of the environment or may be too conservative.

Unfortunately soil columns in a controlled laboratory can not accurately
represent the inhabitant microbial population or presence of the groundwater
table. Only field testing on current land application fields can provide a true
picture of the sensor readings and fluctuations in a natural state.

For accurate determination of the environmental changes, calibration
procedures should be performed on the sensors. Water content probes should
be fitted to a particular quadratic equation for the soil type and composition being
tested. This will help determine the maximum saturation level and alert when
high organic matter starts to form in the soil. The oxygen sensors should be
calibrated for high humidity environments for most accurate readings. There are
no commercially available ORP electrodes to accurately monitor oxidation-
reduction potential in soil environments. Methods to build soil ORP probes exist
and have successfully been used in literature (Ricks 2002, Szogi et al. 2004). No

changes are required for temperature tracking.

78

APPENDIX A

79

 

 

 

 

ORP Readings - All Stages - Column 1

     

 

 

 

 

 

 

 

 

 

 

 

 

 

350 LLL .. LLL L . LL L
Stage 1 ' 0 LBS/ACID” Stages 2 & 3 . 65 LBS/AC/DAY Stage 4:
1000 LBS/AC/DAY
300 .LL L
250
S‘ 200 L
E
n.
S 150
100
50
o .
0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240
Days of Operation
. c1 - Depth A . c139pth B7 751 - Depth 0
— gear. (01.: Depth A) —y,near <9,1 1969,"! B) @3631.- Depth 9)..
Figure A-1. ORP for Column 1
ORP Readings - All Stages - Column a
(Duplicate for Column 1 Conditions)
350LL L . LL L~ .. L
Stages 2 a. 3 . 65 LBS/AC/DAY Stage 4:
, 1000 LBS/AC/DAY
300 , .
4
250
g 200 L
I . ’4. e - 5*
I
150
o . : , .
I . .
100 ’ .-
0
5° 1
l

 

 

 

 

 

15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240

07087- [Septit7A7 - ca - Dept7tt7B 7 7 C8 Lbetfit c7
._ Linger (CB : 999916,) — Linear (98 :rDeApth B) Lineaflca; Depth Cf

 

 

Figure A-2. ORP for Column 8
80

 

 

ORP Readings - All Stages - Column 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stage 1 - 0 LBS/AC/DAY Stages 2.3 & 4 - 65 LBS/ACIDAY]
3m 77 7,77,77,7.__7 77777 77 . ,7. 7, L
I a 1 5"?s .
25° 77 .7 -' M
. i _
5‘ 200 7 °‘
E
a.
8 150 L
100 L _
5° 7 L O L 7 7, ,7 L 7 7 7.
o .
o 15 30 45 so 75 90 105 120 135 150 165 180 195 210 225 240
Days of Operation
7 . 02 - Depth A s 7c?- oep7tt7t B 77 c2 . Daptn7c
:Linear (CZ - Depth A) TUE (C2;Depth B) Linear (Ci-Depth C)
Figure A-3. ORP for column 2
ORP Rssdings - All Stages - Column 7
(Duplicate for Column 2 Conditions)
350 LLL 7.77
Stage 1 - 0 LBS/AC/DAY |Stages 2.3 & 4 - 65 LBS/AC/DAY |
300 L L L LLL L L L L L
250
200
E
5 150
100
O a
50
o l
o 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240
Days of Operation
7 . 7C7 -7De7pth A7 - c7 _ 096th B7777 c7 _ Depth 0

—Linear (C7 - Depth A) —Linear(CLL Depth B) Linear (C7 L Depth (3‘

 

Figure A-4. ORP for Column 7
81

 

 

 

ORP Readings - All Stages - Column 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

350 LL LLL LLLL L L LLLL~ L
Stage 1 - 0 LBS/AC/DAY Stages 2 & 3 - 65 LBS/AC/DAY Stage 4:
1000 LBS/AC/DAY
300 L L L L :
250 L L L
. ' ‘ . e ‘ ‘04 . .
' ‘ . . o. 4’ '- 4%
s... new. LLL-7’75 2'
E 0.3., ’,\W s .0. ..o
I O o e. O .
O
. e ‘
f - I.
- J- } I nab/far,
100 ' 3"7 "l- II.' ' ~'*- :7 77
I I I
I I I I l I f
Mb. f 5 I
i I I I
50 L .L. L ,
I I
o
0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240
Days of Operation
. ca - Depth A - ca :Depth B 77 03 - Depth C
—Linear (CS - Depth A) —Ljnear (CS - Depth B) Linear (CS LyDeplh C)
Figure A-5. ORP for Column 3
ORP Readings - All Stages - Column 5
(Duplicate for Column 3 Conditions)
350 LLLLLLLLLLLL LLLLLLLLL 7.7.77.77777. LLLLLL L LL—L—L L 7777 ‘
Stage 1 - 0 LBS/AC/DAY Stages 2 81 3 - 65 LBS/AC/DAY Stage 4:
500 LBS/AC/DAY
30° 7’ 7 77 7 7 I
e' 7
1'
250 L L L L L LL L i LL
I (77/
9 200
E
o.
g 150
100
O
50 7 L , L L
0
o 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240
Days of Operation
‘7 0 C6 - Depth A 5 06 - Depth B7 7 C6 L Depth7C 77

— Linear (06 - Depth A) fLinear (C6 - Depth B)

7 Linear (06 - Depth C)

 

 

Figure A-6. ORP for Column 6

82

 

 

onp ( mV)

ORP Headings - All Stages - Column 4

 

 

 

 

 

 

 

 

 

550 LL L LL —LLLLLL L LLLLLLLLLL Lfl
50° LAL L ALL LL
*3
450 L | A O .
400 LL | - 3
- C
350 — . ‘ ‘ I L - It I
300 ‘- . e
250 I f a
x— -
200 L W LL
a a
15° if? . o 9 ’0 0 L
c A
100 0 LL
. Stages 3 & 4 ‘
50 Stae 1 - O LBS/AC/DAY Sta e 2 - 65 LBS/AC/DAY 500 LBS/AC/DAY fl
0
o 15 so 45 so 75 90 105 120 135 150 1 5 21
Days of Operation
. c4loépin A 764 - Depth 3 04 - Depth 0 7

— Linear (C47— Depth A) —Llnear (C4 - Depth B) ,L Linear (C4 - Depth fl

 

Figure A-7. ORP for Column 4

 

 

ORP Readings - All Stages - Column 5
(Duplicate tor Column 4 conditions)

 

 

 

 

 

 

 

 

" L L L - L L .° L L L
e
L L L L L 1 fih L LL L
I
Stages 3 & 4
Sta-e 1 - 0 LBS/AC/DAY Sta-e 2 - 65 LBS/AC/DAY L 500 LBS/AC/DAY
0 15 30 45 60 75 90 105 120 135 150 165 150 195 210 225 240
Days of Operation
its-Delhi” JCS-Depths? '7 05709me \

‘j-Linear £35 13$)?“ A)i—- Linger (7057- Depth 8) 7 Linear (95 - DeptitirC)

 

 

Figure A-8. ORP for Column 5
83

 

 

 

ORP (mV)

Oxygen Level vs. ORP

 

 

 

 

 

 

 

Stage3814
65lbslacldeyaveragee
300 - '1 24.0
Stage 3 ‘ Stage 4|
20.0
160 . 066$ Atonp) A
' A - DepthB(ORP)
35, A DepthC(OFiP)
, _
L L L‘ m . A . g . Depmtoa
150 L . L .L :— ‘ ‘ P.‘ 12.0-I I DepthB(02)
A
o ‘ t ‘ ‘ g a Depth C(02)
. ‘ o —Linear(DepthC(OFlP))
1 ‘ —Linear(DepthA(OFiP)) ‘
0° F ' "F 8'0 ¥—Unear(Depth8(ORP))
50 L L L 4.0
o - L— - -L 0.0
158 162 166 170 174 178 182 186 190 194 198 202 206 210 214 218 222

Stages

 

Figure A-9. ORP vs. Oxygen Level for 65 lbs BOD/ac/day

84

 

 

 

ORP (mV)

0

 

Oxygen Level vs. ORP

 

 

 

 

 

 

 

 

   
 

 

 

Stages

Stageaad
500lbslecldeyeverages
t 65*?" * 5 ~ 240
Stage 3 ‘ Stage 4|
Fig i . '5‘ 7 '20.0
*L 16.0
A
A
L
W . le . 0’”:. ..l !! I
7 I 7” 7 ‘ ‘ A A: - I'I I 7120
.- AA““: “ I ... . I.'II ‘
I ‘0... ‘ A
I
e o A A“““““““‘A“A‘A
L L “MA . -- - L — ‘ L-8.o
A‘A“
— — 4.0
’5 LLL "-4 OD
156 162 166 170 174 178 182 186 190 194 198 202 206 210 214 218 22

Oxygen Level (96)

Depth A(091")

Depth 3 (ORP)

Depth C (ORP)

Depth A (02)

Depth 3(02)

Depth C(02) §
—Lineer (Depth 0 (ORP)) i
—Lineer (Depth A (099))
—Lineer erth B (Den) 1

D I O I» a o

 

Figure A-10. ORP vs. Oxygen Level for 500 lbs BOD/ac/day

85

 

APPENDIX B

86

Table B-1. Soil Moisture Post-Calibration Weights

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$8.8 $8.2 830mm 38 $8 $55 :2 e {we 6> m> 4522284 L
38.5, 2 a. E awomdw 3.6. as; :65 came 8:8 o 3 - .928
96$? male? 85.3 .052 5me 555 Ease m
428.8 35.8 «88.8 mag 33 seem <
mmlm Z - Q2 9 £960
82.: 52.3 33.8 $3 83:55 PE 2 x60 m> $9853 8m m
magma 83m 38.2 cm 8% $65 5250 o
$2.3 69.3. 826.3 QNL A3233 m
$2.: Eels. 363.. 33 Sagas <
L . . NL - 39:38
8m :2 33.2 88.8 5.8 New“ 565 532m {3 ems m> 696$me 88 L
:33 LNINLS $2Nfl.l&..& 63:55 539m {8 0
23m $88 $8.98 we? @656 52:65.3: m
38.2. 8mm? 4%.: as, amigos <
. mum. I - Q2 8 £30
368.9. 82.9. 88.2 - am - 682 .295
a 98 E565 vca c265 26m
35213 fiscal. 6529 62.25 scezosaaacsttfio .33 9.63.. 3a 5.5.8
22.3 22.3 22.3 525 3.26 6.8 :8 :85: 58.8
90> to Es
7 0. Sam

 

 

87

Table B-2. Soil Moisture Post-Calibration Calculations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ovmmmd @856 mmmmd 83me m> avenge A
883 883 .3186 688.: o 8 - 6:80
88 L .o 883 888 m 53.". m
880.0 ommmmd $58.0 $8: <
.1 a2 2 £63
«~53 “W86 Etc “3.: m> fiegmma 08 m
29.8.6 8m :3 E83 5 53; o
883 886.0 386 ER: m
«88.0 m 53 $23 mmmmwd <
, . . a2 2 50.60
Same mmmad 85¢ 83.8 m> $3869 88 L
833 ommmmd memmd 22.3w 0
$23 @886 mmmmo m :34“ m
$335 moamd :83 883 <
. . Q2 2 5er
«38.0 :23 888 mmlm8.L - m.coz 659.0
E250 AmEaLa $523 $223 .33 9.5.3.. OOm £53.00
.363 EoEoo m> . 2 26; >5 EEO! Egon
anus. to a «2.3 1:23 to
. .25
_ _ .L 2.8

 

 

88

Table B-3. Oxygen Sensor Post Calibration Data

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Image 8:8 5% N 2.3 «N ..mm @384 a
.8520 2 £38 .me mam Em «.3 mm mm - .258
25% 8 how 3 Rm 3% mm
25% 2. .v rm ..m :3 QB 3m @333 08 m
.8520 g v.58 gmmm 3‘. Km Em 3m
.8220 .mm.m mm «mm m. 5 m.mm
s 25% s 22
I ..Sh mm m S 3,; 8 >838; 88 F
.8220 5% «a 3m 2:. Sm
g 258 3 22
.8520 arm 3 v.3 at. “.8
E 2.an 9:8
382 8.: 2.3 «z 52 $5 9.5 e2 25.3.. o8 5:28
anomm ES.
8. a. 5 EN 5 ES 5 22503359
88.3 883 «833 cozaéao 32.8 «0

 

 

 

 

 

89

BIBLIOGRAPHY

Arizona State University (ASU). 2008. Varian SpectrAA 600 Flame Atomic
Absorption Spectrophotometer. http://www.asu.edu/gerlaa.htm, (accessed
March 29, 2008).

Bailey, LD. and E.G. Beauchamp. 1971. Nitrate reduction, and redox potentials
measured with permanently and temporarily placed platinum electrodes in
saturated soils. Can. J. Soil Sci. (51 ): 51-58.

Bohn, Hinrich L. 1971. Fledox potentials. Soil Science 112:39-45.

Brown and Caldwell. 2007. Manual of good practice for land application of food
processing/rinse water. Davis, California.
http://www.clfp.com/ Man ual/CLFP%20Manual_COMPLETE_F| NAL__3-1 4-
07°/o20(2).pdf (Accessed April 23, 2007).

Bugbee, Bruce and Mark Blonquist. Absolute and Relative Gas Concentration:
Understanding Oxygen in Air.
http://www.apogeeinstruments.com/oxygensensor_techinfo.htm (accessed
November 12, 2007).

Campbell Scientific, Inc. 2006. 08616 and 08625 Water Content Reflectometers.
Logan, Utah.

Campbell Scientific, Inc. 2007. Model 108 Temperature Probe. Logan, Utah.

Crites, R.W., S.C. Reed and R.K. Bastian. 2000. Land Treatment Systems for
Municipal and Industrial Wastes. McG raw-Hill, New York.

Dilly, Oliver. “Microbial Energetics in Soils.” 2005. In Microorganisms in soils:
roles in genesis and functions, edited by Francois Buscot and Ajit Varma,
123-138. New York: Springer.

Donker, Marianne H., Herman Eijsackers, and Fred Heimbach eds. 1994.
Ecotoxicology of Soil Organisms. Boca Raton, Florida: Lewis Publishers.

Gadd, Geoffrey M. 2005. “Microorganisms in Toxic Metal-Polluted Soils.” In
Microorganisms in soils: roles in genesis and functions, edited by Francois
Buscot and Ajit Varma, 325356. New York: Springer.

Hannah Instruments. 2007. Industrial pH/ORP electrodes literature download.

http://www.hannainst.com/usa/prod32.cfm?ProdCode=H|%202000%208eries&id
=017010 (accessed March 21, 2008).

Hillel, Daniel. 1982. Introduction to Soil Physics. New York: Academic Press.

90

Hiraishi, A. 1999. lsoprenoid quinones as biomarkers of microbial populations in
the environment. J Biosci Bioeng 68:449-450.

Islam, K.R. and SR. Wright. 2006. “Microbial Biomass Measurement Methods.”
In Encyclopedia of Soil Science, edited by Rattan Lal, 1067-1070. New York:
Taylor & Francis.

James, Bruce R. 2006. “Redox Phenomena.” In Encyclopedia of Soil Science,
edited by Rattan Lal, 1071-1076. New York: Taylor & Francis.

King, R. Barry, Gilbert M. Long and John K. Sheldon. 1998. Practical
Environmental Bioremediation The Field Guide. Boca Raton: Lewis
Publishers.

Leeson, Andrea and Robert E. Hinchee. 1997. Soil Bioventing Principles and
Practice. Boca Raton: CRC Lewis Publishers.

Lovley, Derek R. 2000. “Fe(l|l) and Mn(IV) Reduction.” In Environmental
Microbe-Metal Interactions, edited by Derek R. Lovley, 3-30. Washinton D.C:
ASM Press.

Margesin R. and F. Schinner (eds.). 2005. Manual for Soil Analysis - Monitoring
and Assessing Soil Bioremediation. Berlin Heidelbreg: Springer.

McDaniel, Paul A. 2006. “Anaerobic Processes.” In Encyclopedia of Soil Science,
edited by Rattan Lal, 97-100. New York: Taylor & Francis.

Mokma, D. L. 2006. Capacity of Soils to Assimilate Wastewaters from Food
Processing Facilities.
http://www.egr.msu.edu/~safferma/Research/Greeen/Deliverables/Assimilati
on%200apacity%2012-8-2007.pdf (Accessed February 18, 2008).

Munsell Color. 2000. Munsell Soil Color Carts. New Windsor, New York:
GretagMacbeth.

Neilson, J.W. and LL. Pepper. 1990. Soil Respiration as an Index of Soil Aeration.
Soil Sci. Soc. Am. J. 54:428-432.

Pansu, Marc, Jacques Gantheyrou and Jean-Yves Loyer. 2001. Soil analysis:
sampling instrumentation and quality control. Exton, Pennsylvania: AA.
Balkema.

Patrick, W.H. Jr. and D. S. Mikkelsen and ER Wells. 1985. “Plant nutrient

behavior in flooded soil.” In Fertilizer Technology and Use, 3rd ed. 197-228.
Madison, WI: SSSA.

91

Paul, EA. and FE. Clark. 1996. Soil Microbiology and Biochemistry. San Diego:
Academic Press.

Quispel, A. 1947. Measurement of the oxidation-reduction potentials of normal
and inundated soils. Soil Science 63: 265-275.

Ricks, Staci N. 2002. Effect of Riparian Buffers on Soil Redox Potential. Raleigh,
North Carolina.

Rittmann, Bruce E. and Perry L McCarty. Environmental Biotechnology:
Principles and Applications. Boston: McGraw Hill, 2001.

Smith, K.A. and R.J. Dowdell. 1974. Relationships between Ethylene, Oxygen,
Soil Moisture Content and Temperature. J Soil Sci 25(2):21 7-230.

Szogi, A.A., P.G. Hunt, E.J. Sadler and DE. Evans. 2004. Characterization of
oxidation-reduction processes in constructed wetlands for swine wastewater
treatment. Applied Engineering in Agriculture 20(2):189-200.

Tarradellas, Joseph, Gabriel Bitton, and Dominique Rossel. 1997. Soil
Ecotoxicology. Boca Raton: CRC Press Lewis Publishers.

Trulear, Michael G. and William G. Characklis. 1982. Dynamics of biofilm
processes. Journal WPCF 54(9): 1288-1301.

U.S. Environmental Protection Agency. 1990. Handbook on In Situ Treatment of
Hazardous Waste-Contaminated Soils. EPA/540/2-90-002. U.S. EPA Risk
Reduction Engineering Laboratory Cincinnati, OH.

U.S. Environmental Protection Agency. 1992. Bioremediation of Hazardous
Wastes. EPA/600/R-92/126. U.S. EPA Office of Research and Development,
Washington, DC.

Yaniga, PM. and W. Smith. 1986. Aquifer Restoration Via Accelerated In Situ
Biodegradtion of Organic Contaminants. In Proceed. Of the 7‘" National
Conference on Management of Uncontrolled Hazardous Waste Sites. Dec
1-3, Washington DC.

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