Pig farm wastewater treatment

Pig farm wastewater treatment refers to the effective treatment of wastewater generated during pig farming to remove organic matter, nitrogen and phosphorus nutrients, pathogenic microorganisms, suspended matter and harmful gases, so that it meets the national or local emission standards or reuse requirements. Pig farm wastewater has the characteristics of high concentration of organic matter, high ammonia nitrogen, high suspended matter, easy to corrupt, etc., which is difficult to treat. The following is a complete set of pig farm wastewater treatment processes and their key links: 1. Pretreatment stage - solid-liquid separation: First, solid-liquid separation is carried out by mechanical or natural sedimentation, such as using screens, sedimentation tanks, screw extruders and other equipment to separate solid substances such as feces and feed residues from wastewater as compost or biomass energy raw materials. - Sedimentation tank: The pretreated wastewater enters the sedimentation tank to further remove suspended matter, and at the same time, some organic matter and ammonia nitrogen are initially reduced through natural sedimentation and initial biodegradation. - Flocculation sedimentation: Add flocculants (such as polyaluminum chloride, polyacrylamide, etc.) at the outlet of the sedimentation tank to accelerate the aggregation of suspended matter and colloidal particles, forming flocs that are easy to precipitate, and further improve the sedimentation effect. 2. Biological treatment stage - Anaerobic digestion: wastewater enters anaerobic reactors (such as UASB, IC, AF, etc.) for anaerobic fermentation. Under anaerobic conditions, microorganisms decompose organic matter into biogas (mainly methane and carbon dioxide), biogas bubbles and residual sludge. Anaerobic digestion can not only significantly reduce the concentration of organic matter, but also recover energy (biogas), and the produced biogas residue (anaerobic sludge) has good agricultural utilization value. - Aerobic biological treatment: anaerobic effluent enters aerobic bioreactors (such as activated sludge process, biological contact oxidation process, SBR, MBR, etc.) for further treatment. Aerobic microorganisms use oxygen to oxidize organic matter into carbon dioxide, water and microbial cells, and convert ammonia nitrogen into nitrates through nitrification. Common aerobic processes include A/O (anaerobic-aerobic) process, A2/O (anaerobic-anoxic-aerobic) process, etc., and the appropriate process combination can be selected according to actual needs. 3. Advanced treatment stage - Chemical phosphorus removal: If the phosphorus content of the effluent still cannot meet the discharge standard, chemical phosphorus removal facilities can be added after the aerobic effluent, such as adding coagulants such as iron salts and aluminum salts to make phosphates and metal ions form insoluble precipitates, which can be removed by precipitation or filtration. - Biological nitrogen removal: For high-ammonia nitrogen wastewater, new biological denitrification technologies such as anaerobic ammonia oxidation (Anammox) process or short-range nitrification and denitrification can be used to achieve efficient removal of ammonia nitrogen in a more energy-saving way. - Filtration/precipitation: Suspended matter and some soluble organic matter in the wastewater are further removed through physical filtration methods such as sand filtration, fiber ball filtration, microfiltration, ultrafiltration, or high-efficiency sedimentation tanks. 4. Disinfection treatment - Disinfection and sterilization: Disinfection methods such as ultraviolet rays, chlorine dioxide, sodium hypochlorite, etc. are used to disinfect the treated wastewater to kill pathogenic microorganisms and ensure the safety of the effluent. 5. Sludge treatment and disposal - Sludge concentration: The residual sludge generated from the biological treatment system is reduced in volume and increased in solid content by gravity concentration, mechanical concentration and other methods. - Sludge dehydration: The concentrated sludge is dehydrated by plate and frame filter press, belt filter press, centrifugal dehydrator and other equipment to form a mud cake with low moisture content, which is convenient for transportation and subsequent disposal. - Sludge disposal: Dehydrated sludge can be composted, dried and landfilled, incinerated or used to make building materials and other resource utilization methods, or it can be finally disposed of in a suitable way according to local policies and conditions. 6. Effluent reuse or compliance discharge - Effluent testing: The treated wastewater must be tested in the laboratory to confirm that all indicators meet the discharge standard or reuse standard before it can be discharged or reused. - Reuse: Effluent that meets the requirements can be used to flush pig houses, irrigate farmland or as industrial cooling water, etc., to achieve the recycling of water resources. 7. System operation and management - Daily monitoring: Regularly monitor the water quality of each link of sewage treatment, and adjust the operating parameters in time to ensure stable and efficient operation of the system. - Equipment maintenance: Regularly inspect, maintain and repair the equipment to prevent the treatment effect from being affected by equipment failure. - Emergency plan: Develop an emergency plan to deal with emergencies to ensure that measures can be taken quickly in abnormal circumstances to prevent environmental pollution. In summary, pig farm sewage treatment is a multi-link, multi-process collaborative treatment process. It is necessary to comprehensively consider factors such as treatment effect, operating cost, energy recovery, and environmental impact, and scientifically and rationally design and operate the sewage treatment system.