STUDIES ON FOUNDRIES IN HOWRAH

Utilisation of domestic sewage for fish farming is practised since long with tremendous success. This unique system not only treat the sewage but also turn into profit for community involved. The Zonal Office, Calcutta, has launched a monitoring programme to evaluate the effectiveness of this system. The results indicated an overall reduction of about 50% BOD, 80% Ammonia, 60% TKN, 65% Phosphate with more than 99% reduction of total coliforms, fecal coliforms & streptococci. This system not only reduce the pollutant significantly, but also yield valuable by-product like plankton (food for fish), algae, fishes etc. Profuse growth of algae and zooplankton indicate the utilisation of nutrients readily available in the sewage. As observed, there is still ample scope to enhance its capacity through optimisation of stock density, addition of sewage, composition of fish, prevention of excess algal growth, maintenance of DO level, mode of harvesting, addition of nutrients, liming of soil etc.