A greenhouse ecosystem, often referred to as a Living Machine©, is a technology for biological wastewater treatment using plants in a greenhouse structure. It has a small footprint relative to traditional onsite systems, has been shown to manage high strength wastewater, and can provide a high level of treatment to allow for reuse for purposes such as irrigation, toilet flushing, and landscaping. Craft beverage wastewater (water from wineries, breweries, and cideries) is considered high strength and contains chemical oxygen demands (COD) close to 20,000 mg/L, total nitrogen up to 80 mg/L, and total phosphorus up to 70 mg/L. Due to the variability of the wastewater in both flow and composition, it is hard to treat with a conventional wastewater treatment system. The ability of this system to treat craft beverage wastewater is determined through this project. The experimental system consisted of three parallel systems, with one always serving as a control to treat representative synthetic winery wastewater. Each system had three reactors in series with 5 species of plants native to Michigan. The first two reactors had 12-hour aeration cycles. Synthetic wastewater was prepared to test the ability of the system to treat a variety of wastewater characteristics that are found from these sources. Once the performance of the greenhouse ecosystem is understood for various wastewater characteristics, actual wastewater from the three sources will be tested. Wastewater characteristics that were routinely measured included pH, dissolved oxygen, and conductivity, as well as visually inspecting the plants. Nitrate, nitrite, ammonia, total nitrogen, COD, and total phosphorus levels were measured weekly. Results show the system is effective within the designed organic and hydraulic loadings. However, extreme events will cause disruptions and potential system failure. An example of an extreme event is having a high concentration of COD. Aeration was found to be a key factor in reducing the odor produced from treating the wastewater. The greenhouse ecosystem can also be scaled up, as the volume and flow are known for a specific loading rate. Next steps include performing an economic analysis, performing optimization experiments to determine the best plants to use, monitoring more sample types (such as total Kjeldahl nitrogen and nitrogen gas), performing microbial analyses, and performing a field scale experiment.
Read
