The main characteristics of wastewater discharged from pig farms are high organic matter concentration, high suspended solids, deep color, and the presence of a large number of bacteria. The high concentration of NH3-N is due to the presence of a large amount of animal feces and urine. The pollutants in wastewater mainly exist in the form of solid and dissolved carbohydrates, which cause the wastewater to exhibit high BOD5, CODcr, SS, and chromaticity. The pollutants have good biodegradability, and in addition, the wastewater contains a large amount of nutrients such as N and P.

The solid residue in wastewater is mainly organic matter. If effective solid-liquid separation is not carried out, it will bring difficulties to subsequent treatment, increase treatment load, and affect treatment efficiency. Therefore, pre-treatment must be strengthened in the process. The use of physical methods as an enhanced pretreatment process for solid-liquid separation of wastewater is an effective method to reduce organic load. Physical methods have a small footprint, high treatment efficiency, and are not affected by other conditions such as load, water quality, temperature, etc., and do not cause secondary pollution to the environment

After years of practice, it has been proven that biochemical treatment is an effective and economical treatment technology for easily biodegradable organic wastewater, including anaerobic, aerobic technologies, and stabilization ponds. For organic wastewater with high concentration, anaerobic treatment alone generally cannot meet the treatment requirements. Aerobic treatment alone has high operating costs. The anaerobic aerobic cascade process combines the advantages of anaerobic and aerobic treatment processes to avoid their respective disadvantages. Anaerobic treatment processes have low energy consumption, low sludge production, and high load, but the effluent does not meet the standards; The aerobic treatment process has good effluent quality and stable operation, but it requires energy consumption and high sludge production. Therefore, the anaerobic aerobic cascade process has significant advantages in energy consumption, investment, treatment cost, and treatment effectiveness. Based on the water quality characteristics of the wastewater and the specific conditions of the pig farm, combined with the successful experience of multiple projects, and adhering to the principles of low investment, low operating costs, and convenient operation and management, we have determinedUASB anaerobic improved SBR disinfection facultative pond treatment process.

Process flowchart: