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Wastewater from pig farms contains a high level of organic pollutants. Without proper treatment, it may cause serious water pollution. This article introduces a highly effective and widely applicable treatment process for pig farm wastewater. The goal is to help farms meet environmental discharge standards while ensuring system stability and cost control.
Characteristics and Challenges of Livestock Wastewater
Livestock wastewater typically contains high concentrations of COD, BOD, ammonia nitrogen (NH₃-N), suspended solids (SS), and total phosphorus (TP). Key characteristics include:
- High organic load: From manure, leftover feed, and cleaning water.
- Solid-liquid mixture: Requires effective separation of suspended and dissolved substances.
- High ammonia and phosphorus: Can lead to eutrophication if discharged untreated.
👉 An efficient treatment process must address organic matter degradation, nitrogen/phosphorus removal, solid-liquid separation, and compliance with discharge standards.
Livestock Wastewater Treatment Process Flow
(1) Raw Water Collection & Pretreatment
Wastewater is first collected in a holding tank, where coarse solids are removed using bar screens to prevent equipment clogging. It then passes through a solid-liquid separator to reduce the concentration of suspended particles.
(2) Coagulation sedimentation or air flotation pretreatment
To remove more suspended solids and large organic molecules, wastewater enters a coagulation tank or dissolved air flotation (DAF) system. Here, PAC (polyaluminum chloride), PAM (polyacrylamide), and alkali (e.g., NaOH) are added for chemical precipitation.
(3) Equalization Tank-Balanced water quality and quantity
Pretreated wastewater flows into an equalization tank (or primary sedimentation tank) to balance flow rate and pollutant concentration, ensuring stable performance in the following biological stages.
(4) Anaerobic Treatment – High COD Removal
Due to the high COD load, anaerobic treatment is used for effective degradation. Common systems include:
- Black Membrane Anaerobic Digester (low cost, suitable for large-scale farms)
- UASB (Upflow Anaerobic Sludge Blanket) reactors, which increase COD removal efficiency.
(5) Multi-stage AO (Anoxic–Oxic) Biological System：nitrogen and phosphorus removal,deep purification
The anaerobically treated water enters a multi-stage AO process for deep purification. This step removes nitrogen, residualCOD, and partial phosphorus, followed by secondary sedimentation for further solid-liquid separation.
(6) Advanced Treatment & Final Discharge
- Suspended solids removal: If suspended solids remain high, PAC or polyferric sulfate (PFS) is added for further sedimentation.
- Phosphorus removal: Apply phosphorus removal agents as needed to meet total phosphorus limits.
- Filtration & disinfection: Use sand filters and activated carbon to reduce color and odor. Finally, sodium hypochlorite is used for disinfection before safe discharge.
Key Advantages of the Treatment System
✅ Wide applicability: Suitable for both small- and large-scale pig farms and high-strength organic wastewater.
✅ Stable treatment performance: Multiple stages ensure compliance with COD, NH₃-N, and SS standards.
✅ Cost-effective operation: Process units are optimized to reduce chemical use and energy consumption.
✅ Meets regulatory requirements: Ensures treated water meets national environmental discharge standards and lowers pollution risks.
Conclusion
Effective treatment of livestock wastewater is essential not only for regulatory compliance but also for the sustainable development of animal farming operations. Choosing the right process can lower operational costs and reduce environmental impact—paving the way for greener, cleaner agriculture.
📌 We hope this guide provides valuable insight into livestock wastewater treatment. For tailored solutions or technical support, feel free to contact our team.
