Post-fermentation effluent from anaerobic fermentation of sewage sludge was treated with microalgal cultures (Chlorella sorokiniana and an environmental consortium) under fluorescent white light for 7 days, then supplemented again with a 2nd dose of microalgal biomass and incubated for the next 7 days. During the first week, no change in NH(4)(+)concn. was obsd. The PO43- concn. decreased slightly but both the no. of bacteria as well as chem. O-2 demand significantly increased. After the 2nd treatment week, the concn. of PO43- and NH4+ decreased by 72-83% and 38%, resp., whereas chem. O-2 demand decreased by 55%. The optimized microalgal treatment stimulated the biol. remediation processes in sludge lips.