Research on the operation characteristic of CASS process under long influent and short aerobic phase

Characteristic of pollutants removal in CASS process under long influent and short aerobic time were carried out to achieve CASS technique maintain high biological nutrient and phosphorus removal capabilities under low temperatures. The operation model of main reaction zone was 4 hours influent with mixing, 2hours aerobic, 1 hour sedimentation and 1 hour effluent, aerobic phase was operated after 2 hours influent. In the first 2 hours influent phase, phosphorus release and denitrification were observed in three zones of CASS reactor. The total amount of phosphorus released can reach 9.5 times as large as the amount of influent phosphorus. The operation mode of CASS process under long influent and short aerobic phase has good effluent quality and the effluent concentration of COD and ammonia can still reach level A standard.