Municipal wastewater stabilization and the potential reuse for African Catfish (Clarias gariepinus) culture in waste-fed earthen ponds in the tropics

Abstract In many low to middle income countries like Ghana, most wastewater treatment plants operate below capacity owing to lack of maintenance and lack of proper management. This affects the stabilization efficiency of treatment plants. The Chirapatre wastewater treatment plant was established to serve as a model system for municipal wastewater treatment in the Ashanti region of Ghana, however, very little is known about its stabilization efficiency. This study evaluated the current stabilization efficiency of the Chirapatre stabilization ponds for municipal wastewater treatment, as well as the potential reuse of the stabilized effluents for wastewater-fed aquaculture. Stabilization efficiency (SE) were assessed using the physico-chemical analysis of the influent at the anaerobic stabilization pond and effluent at discharge of the 2nd maturation pond. African catfish Clarias gariepinus fingerlings of average size 40g were stocked into two maturation ponds at a density of 3 fish/m2. Fish were not fed during the study period. Sampling was done every 14 days to monitor growth, and total fish harvest was done at the end of the study (12th week). Variables monitored included: fish survival and growth performance (condition factor, weight gain, specific growth weight and yield) as well physicochemical water quality parameters. The results indicated that TSS, TDS, alkalinity, ammonia, COD, and BOD5 stabilization efficiency were 89.99%, 62.21%, 37.54%, 67.21%, 91.33% and 88.77% respectively. The plant was non-compliant in terms of morning DO and the ammonia levels in effluents which posed lethal to aquatic life in receiving waters. However, the plant satisfied the USEPA and GEPA standards for all other physicochemical parameters including the DO (evening) concentrations in effluent. Fish survival of > 65% with > 30 condition factors and fish yields of > 1500 kg/ha were recorded at the end of the study.