TREATMENT OF DOMESTIC SEWAGE FROM RURAL SETTLEMENTS BY A MEMBRANE BIOREACTOR

This study examined the feasibility of applying a membrane bioreactor to small wastewater treatment using a pilot-scale plant. The operation was continued for 336 days. From the start to 251st day, the operatio n was continued without membrane washing. During the latter term of th e operation, however, suction pressure increased rapidly corresponding to the increase of sludge viscosity. Because sludge viscosity increas e occurred right after the suspension of sludge wasting, excess sludge must be wasted at regular intervals in order to keep low sludge visco sity. More than 90% of organic matter, suspended solids; and coliform bacteria were successfully removed. As far as nitrogen removal was con cerned, denitrification was the rate determining step in this system. To enhance denitrification, the following three points should be consi dered: i) to concentrate inflow of raw sewage at the beginning of anox ic period, ii) to shorten aeration time, and iii) to maintain high MLS S concentration. Copyright (C) 1996 IAWQ. Published by Elsevier Scienc e Ltd.