Reclamation of Municipal Wastewater

The feasibility of applying direct advanced treatment to municipal wastewater has been investigated. A. two-stage scheme was implemented. The first stage was direct chemical coagulation of primary effluent using different coagulants to remove suspended solids and reduce the carbon to nitrogen ratio to a range suitable for nitrification. The second stage was biological sand-bed to oxidize ammonia to nitrate. The pilot plant was designed to treat 6m3/day. The results obtained showed that chemical coagulation using ferric chloride gave high quality effluent suitable for agricultural purposes. Nitrification of the 2 chemically treated effluent using sand-bed at an overflow rate of 1.358 m3/m2/d completely eliminated ammonia. Almost complete removal of suspended solids was achieved. Residual COD and BOD values were 45 mg/l and 15,5 mg/l, respectively. Fish biotoxicity was completely eliminated after nitrification process.