Activated sludge biofilm wastewater treatment system

Plastic nets were fitted vertically inside the aeration tank of a conventional activated sludge process in a laboratory scale model. The aeration tank thus became a hybrid growth reactor combining both suspended and fixed biomass. The addition of nets resulted in considerable improvements in BOD5 removal efficiency and sludge settling efficiency for a synthetic wastewater. Theoretical mathematical models predicting the performance of the hybrid growth reactor were proposed and their accuracy was affirmed by comparison with the experimentally measured results. The process has been termed Activated Sludge Biofilm Wastewater Treatment System (ASBWTS). Existing plants can be upgraded by the fitting of plastic nets in the aeration tank and new systems can be constructed at a reduced cost if plastic nets are used.