Influence of physicochemical parameters on the removal of nitrogenous compounds during treatment of fish effluent with seaweeds

Fish effluent was treated with Gracilaria corticata and Ulva lactuca in separate tanks. Effluent without seaweeds was kept as control. Physicochemical parameters such as pH, Biological Oxygen Demand, Dissolved Oxygen on nitrogenous compounds such as ammonia, nitrite and nitrate were monitored. The DO content was found to be 15 % more in the treatment tanks of G.corticata (5.44 ml/l) when compared to the control (4.05 ml/l) during same period, may account for the high photosynthetic activity and efficient utilization of dissolved carbon in the effluent. The BOD value was observed to be more in the treated tank of G.corticata compared to control on 20 days of treatment, could be due to the growth of associated bacteria in the system, which favoured the oxidation of ammonia to nitrite and then to nitrate. The pH was found to have significant positive correlation with nitrate content in all the treatments, whereas BOD exhibited a negative correlation with nitrate. The removal of nitrogenous compounds was found to be more in the effluent treated with U. lactuca followed by G. corticata than the control.