A cooling water system as a biofilm reactor for the treatment of municipalwastewater

In this study, a water cooling tower war used as a low-rate biofilm reactor for treating municipal wastewater. The performance of the system was evalu ated at three different flow rates (5 l.s(-1), 2 l.s(-1) and 1.6 l.s(-1)). The biofilm reactor gave the best results at a flow rate of 1.6 l.s(-1), na mely: 43.3% nitrogen removal, 42.3% chemical oxygen demand (COD) removal, 1 .7% phosphorus removal and 39.8% suspended solids (SS) removal. These resul ts were achieved with a once-through flow and low organic (19 g COD.m(-2).d (-1)) and hydraulic loads (0.173 m(3).m(-2).d(-1)). This type of biofilter system is being used in West Malaysia to treating municipal effluents. Our system performance, at a flow rate of 1.6 l.s(-1) was capable of treating m unicipal wastewater to meet general effluent standards in South Africa (Gov ernment Gazette, 1984). This is sufficient for treating effluent for a popu lation equivalent of 2 800 people.