water recycling – Livestock and Poultry Environmental Learning Community

April 2, 2025

Advanced Multi-Stage Wastewater Treatment for Sustainable Dairy Farm Management

Purpose

Dairy farms employing flushing systems often encounter significant challenges in managing substantial volumes of recycled water, which can have environmental, economic, and operational implications. This study aims to evaluate a multi-stage process designed to improve solid/nutrient extraction from flushed water already treated by a pull-plug sediment basin system.

What Did We Do?

We implemented a three-stage sequential treatment process comprising coagulation, Fenton oxidation, and membrane filtration. In the first stage, coagulation was performed using aluminum sulfate (Al₂(SO₄)₃) to remove colloidal solids from the treated barn flushing water. The optimal alum dosage (500–7,000 mg/L) was determined based on turbidity, total solids, and chemical oxygen demand (COD) removal.

The second stage involved Fenton oxidation, where hydroxyl radicals generated from hydrogen peroxide (H₂O₂) and an iron catalyst (Fe²⁺) further degraded organic pollutants. Utilizing response surface methodology (RSM), we optimized the concentrations of H₂O₂ (500–1,800 mg/L), FeCl₃ (250–950 mg/L), and reaction time (15–50 min) to achieve a balance between treatment effectiveness and cost efficiency.

In the final stage, ultrafiltration and reverse osmosis were employed to remove dissolved ions, ensuring compliance with discharge standards.

What Have We Learned?

Fig. 1. Removals of turbidity (a), total solid (b), COD (c), and impacts on pH (d) at various alum treatment concentrations.

The results indicated that turbidity removal peaked at a dosage of 5,000 mg/L of Al₂(SO₄)₃, while total solids and COD removal stabilized at 4,000 and 5,000 mg/L, respectively. Although turbidity initially increased following the coagulant addition, the formation of aluminum hydroxide flocs facilitated effective pollutant removal. To balance reagent costs and treatment efficiency, a dosage of 4,000 mg/L alum was selected. After coagulation, the coagulated supernatant underwent fenton oxidation.

Turbidity removal (%)

Fig. 2. The removal of turbidity (%) at the interactions between H2O2 and FeCl3 (a), between H2O2 and time (b), and between FeCl3 and time (c). — Fig. 2. The removal of turbidity (%) at the interactions between H₂O₂ and FeCl₃ (a), between H₂O₂ and time (b), and between FeCl₃ and time (c).

Response surface analysis confirmed that optimal turbidity removal was achieved with H₂O₂ concentrations of 1,280-1,800 mg/L and FeCl₃ concentrations of 550-950 mg/L. Furthermore, a minimum mixing of 36 minutes was necessary to attain maximum efficiency.

Total solid removal (%)

Fig. 3. The removal of total solid (%) at the interactions between H2O2 and FeCl3 (a), between H2O2 and time (b), and between FeCl3 and time (c). — Fig. 3. The removal of total solid (%) at the interactions between H₂O₂ and FeCl₃ (a), between H₂O₂ and time (b), and between FeCl₃ and time (c).

For total solids removal, effective interaction was observed at H₂O₂ levels of 500–1,240 mg/L and FeCl₃ concentrations of 250–450 mg/L. Mixing times exceeding 43 minutes were found to reduce removal efficiency.

COD removal (%)

Fig. 4. The removal of COD (%) at the interactions between H2O2 and FeCl3 (a), between H2O2 and time (b), and between FeCl3 and time (c). — Fig. 4. The removal of COD (%) at the interactions between H₂O₂ and FeCl₃ (a), between H₂O₂ and time (b), and between FeCl₃ and time (c).

COD removal was most effective within the H₂O₂ range of 500–760 mg/L and FeCl₃ concentrations of 450–950 mg/L, while mixing time had minimal impact.

Cost ($)

Regarding treatment cost, H₂O₂ was identified as the most influential cost factor due to its higher price. To balance removal efficiency and cost, the optimized conditions were determined as 563.3 mg/L H₂O₂, 568.4 mg/L FeCl₃, and a 33-minute reaction time, according to the calculations of RSM model. This setup achieved 86.4% turbidity removal, 18.7% total solids removal, and 81.5% COD removal at a treatment cost of $0.03 per liter of wastewater.

Future Plans

The next phase of the study will focus on membrane filtration experiments to further remove dissolved ions and ensure compliance with discharge standards. Additionally, a systematic economic analysis will assess cost-effectiveness, scalability, and operational feasibility for large-scale dairy farm applications.

Authors

Presenting author

Moh Moh Thant Zin, Post-doctoral researcher, University of Missouri-Columbia

Corresponding author

Teng-Teeh Lim, Extension Professor, University of Missouri-Columbia, limt@missouri.edu

Acknowledgements

Funding is provided by USDA-NIFA, grant award (2018-68011-28691) and University of Missouri Extension.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7-11, 2025. URL of this page. Accessed on: today’s date.

April 21, 2022November 18, 2024

A Decision-Support Tool for The Design and Evaluation of Manure Management and Nutrient Reuse in Dairy and Swine Farm Facilities

Purpose

The decision-support tool (DST) being developed facilitates the selection of manure treatment technology based on farm needs and nutrient balance requirements. A life cycle assessment (LCA) approach is used to determine and allocate among sources the whole-farm greenhouse gas (GHG) emissions and environmental impact of different manure management systems (MMS) to facilitate decision-making. The purpose of the tool is to help users identify the suite of technologies that could be used, given the farm’s unique set of preferences and constraints. The tool asks for an initial set of farm details and these values are cross-checked with predefined conditions before starting the simulation. This tool helps in the rapid quantification and assessment of treatment technology feasibility, GHG emissions, environmental, and economic impacts during the manure management decision-making process (Fig. 1). The decision algorithm operates based on user input for weightage priorities of criteria and sub-criteria related to environmental, economic, and technical components.

What Did We Do?

The DST is a Microsoft Excel-based tool with precalculated mass balance for a selected number of MMS alternatives representing current and emerging treatment technologies and practices. The MMS considered for the tool includes various handling systems, aerobic and anaerobic treatment systems, solid-liquid separation techniques, chemical processing units, etc. Modules were developed based on mass and energy balances, equipment capital & operating costs, unit process, and technology performance, respectively. The tool utilizes data specific to the country/region/farm where feasible and default values to calculate the overall economic and environmental performance of different MMS, providing results unitized per animal/day or per year.

Then, an LCA approach is used to evaluate the potential environmental footprints of each MMS considered. A life cycle impact assessment (LCIA) is comprised of detailed quantification of inputs and outputs of material flows in a specific treatment and/or conversion process. At the output level, it also defines and quantifies the main product, co-products, and emissions. The major focus on the treatment methods is quantifying the raw materials (manure, wash-water, bedding, etc.) that are to be handled in each MMS, thereby characterizing the properties of effluents (nutrients, gas emissions, etc.). The results include carbon, energy, water, land, nitrogen, and phosphorus footprints along with the effluent nitrogen, phosphorous, and potassium concentrations.

What Have We Learned?

Systematic selection of appropriate technology can provide environmental and economic benefits. Manure management systems vary in their design, due to individual farm settings, geography, and end-use applications of manure. However, the benefits of technological advancements in MMS provide manure management efficiencies and co-production of valuable products such as recycled water, fiber, sand bedding, and nutrient-rich bio-solids, among others. The handling efficiencies and environmental benefits provided by manure treatment technologies come with additional costs, however, so the tradeoffs between environmental benefits and implementation costs also need evaluation.

Future Plans

The next steps are to finalize the dairy module. We are refining the tool’s user interface and demonstrating to stakeholders to gather information regarding key assumptions, outputs, and the functionality of the tool. Further, we also plan to complete the swine module.

Authors

Sudharsan Varma Vempalli, Research Associate, University of Arkansas

Corresponding author email address

svvempal@uark.edu

Additional authors

Sudharsan Varma Vempalli, Research Associate, University of Arkansas

Erin Scott, PhD Graduate Assistant, University of Arkansas

Jacob Allen Hickman, Project Staff, University of Arkansas

Timothy Canter, Extension Specialist, University of Missouri

Richard Stowell, Professor, University of Nebraska-Lincoln

Teng-Teeh Lim, Extension Professor, University of Missouri

Lauren Greenlee, Associate Professor, The Pennsylvania State University

Jennie Popp, Professor, University of Arkansas

Greg Thoma, Professor, University of Arkansas

Additional Information

Detailed economic impacts and tradeoffs expected with the implementation of certain MMS related to this tool is presented during the conference by Erin Scott et al., on the topic “Evaluating Costs and Benefits of Manure Management Systems for a Decision-Support Tool”.

Varma, V.S., Parajuli, R., Scott, E., Canter, T., Lim, T.T., Popp, J. and Thoma, G., 2021. Dairy and swine manure management–Challenges and perspectives for sustainable treatment technology. Science of The Total Environment, 778, p.146319. https://www.sciencedirect.com/science/article/pii/S0048969721013875

Acknowledgements

We acknowledge funding support from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) grant award (# 2018-68011-28691). We would also like to thank our full project team and outside experts for their guidance on this project.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

March 5, 2019March 20, 2019

Evaluation of a Solid-Liquid Manure Separation Barn

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Purpose

This paper documents an on-going evaluation of an existing, full-scale solid/liquid separator barn for the potential of improved manure nutrient conservation and management, water recycling, including cost and handling implications. The barn has V-shaped pit floor to drain liquid manure, and automated scrapers to collect solid manure frequently. The finishing barn was built to improve indoor air quality, and improve manure handling and land application of nutrients.

What did we do?

Collected monthly manure samples (both solid and liquid manure samples) at the commercial barn starting in September, 2016. The collected samples were analyzed for important manure nutrients, pH, and moisture content.
Monitored daily liquid manure production by measuring the water level fluctuation in the receiving pit, using a liquid pressure data logger (U20L-04, HOBO Water Level, Onset Computer Corporation, Bourne, MA). A new pressure gauge with two sensors was then added to allow simultaneous measurement of atmospheric pressure to improve accuracy.
Monitored accumulation of solid manure, by measuring dimensions of the manure pile during each sampling event. A camera was purchased and installed at the storage shed to take hourly photos of the storage pile.
Conducted filtration pilot tests using water and salty water and a bench-scale cross-flow treatment system, capable of various filtration options including reverse osmosis.
Conducted settling/pre-treatment tests of the liquid manure samples, by storing liquid manure in individual jars and periodically characterizing settling of manure solids and duration needed before the high-pressure filtration.

What have we learned?

Battery-operated gauges were able to closely monitor the water level, liquid manure flow, and operation of the pump, and the dual-sensor gauge was much easier in data analysis and downloading. The daily liquid manure level fluctuated significantly during the first six months of monitoring, which could be due to differences in animal size and occurrence of barn washing. Solid manure samples collected in the current project had higher moisture contents than the four samples collected in 2014, meaning the solid/liquid separation barn was not as effective in separating solids and liquids as in 2014. But, the settling tests suggest a settling basin could be designed to pre-treat the liquid manure stream before a water extraction process.

Figure 2. Daily liquid manure separated by the solid/liquid separation barn

Future Plan

A year’s worth of data will be collected, and manure nutrient flows of the solid and liquid portions will be quantified. The team will also characterize and compare the barn and management costs (relative to a typical deep-pit barn), practicality, and costs of the use of filtration and reverse osmosis. Will provide pork producers information on potential for the solid/liquid separation barn and filtration process to improve nutrient management, land application, and water conservation.

Corresponding author, title, and affiliation

Teng Lim, Associate Professor, Agricultural Systems Management, University of Missouri

limt@missouri.edu

Other authors

Joshua Brown, Graduate Research Assistant; and Joseph M. Zulovich, Assistant Professor; Agricultural Systems Management, University of Missouri.

Additional information

Teng Lim, limt@missouri.edu

Acknowledgements

The authors would like to thank the National Pork Board and University of Missouri Extension for financial support, and the farm management team for their help with the project.