a suspended aerobic microbial culture is used to treat the incoming wastewater in activated sludge processes.at the end of reaction period the microbial culture is separated from the liquid being treated.most of the culture is returned and mixed with incoming wastewater.under conditions existing in the activated sludge process,the microbial culture grows in clumps or flocs that contain large numbers of bacteria held tegather by the secreted polymers that accumulate on their capsules
