Wastewater treatment and reuse for aquaculture

A continuous laboratory scale model, simulating an oxidation pond system has been used to investigate the treatability of municipal wastewater and to evaluate the treated effluent for aquaculture. While the detention period was kept constant at 25 days, the organic loading rate fed to the system changed with changes in the BOD5 of the raw sewage and varied from 15.7 to 58.3 with an average value of 34.1 kg BOD5/ha/day. Monitoring of the system indicated remarkable improvement in the water quality of the treated effluent. BOD5 was around 26 mg O2/l. Average residual values of COD, suspended solids and phosphorus were 154, 65 and 3.2 mg/l respectively. A reduction up to 99.99% in coliform bacteria population has been recorded. However, residual values were still high. Tilapia fish grew healthily during the study period. Daily growth rate was 1.43% of the body mass. The productivity was 7.15 kg/ha/day. The corresponding extrapolated yield was 26.09 t/ha/yr which is considered to be a high yield as compared to published information.