A two-stage aerobic treatment consisting of conventional active sludge treatment followed by membrane bio reactor has been tested for 100 days. The overall pollutant removal efficiencies (97.1% COD, 99.5% BOD₅, 94.7% total nitrogen and 72.9% total phosphorous) are high enough to produce effluent that meets criteria for discharge to surface water with a relatively low amount of surplus sludge: 0.34 gSS (gCOD_removed)^-1. The only exception is total phosphorous concentration. The analysis of biodegradable COD in the effluent shows that only 14% is still biodegradable. Although the high quality effluent may be reused in preliminary soiled potato washing, the limiting criteria may be an increased concentration of chlorides.