Contact Stabilization

The contact stabilization activated sludge process (CSASP) typically achieves the same treatment efficiency in a smaller volume than conventional activated sludge plants. CSASP is particularly suited for small to mid-scale plants where influent wastewater contains a high fraction of particulate COD. With CSASP, the same amount of mass sludge can be retained in the system with almost 30% volume reduction compared to conventional activated sludge plants.

By keeping the majority of the biomass in the stabilization reactor, the nominal hydraulic retention time of the system decreases. However the sludge distribution factor must be high enough to ensure an acceptable effluent quality.

At The Colony, TX, Entex used 24 Webitat modules to convert the system from CSASP to Activated Sludge using the existing basins. Overall system capacity was increased by 33%, and the treatment was upgraded from simple carbonaceous removal to nitrification to meet the stricter effluent requirements.