Intensified activated sludge process with submerged membrane microfiltration

A pilot bio-reactor based on the Kubota membrane filtration system using screened domestic sewage has shown impressive results. Operating with an average MLSS of 16,000 mg/l and 4.5 hours HRT the bio-reactor produced a very high quality effluent with typical values of 4 mg/l and 5 mg/l for BOD and NH 4 -N respectively. The sludge age from the bio-reactor was about 45 days. The cost of secondary treatment by membrane bio-reactor (including land and civil costs) starts from 12 p/m 3 for a 1.4 Ml/d plant and reduces to 6p/m 3 for a 22.5 Ml/d plant based on full treatment up to 3DWF. The corresponding treatment costs by conventional technologies are 13 p/m 3 for a 1.4 Ml/d SBC plant and 5 p/m 3 for a 22.5 Ml/d FBDA activated sludge plant.