Application of immobilized microalgae for removing nitrogenous compound from mahseer rearing system

Abstract

The immobilized green microalgae Nannochloropsis sp. in sodium alginate bead was used for the removal of nitrogenous compound from mahseer rearing system. The efficiency of the treatment system was compared among immobilized microalgae, blank alginate bead and control (without alginate bead). All of the treatment system was conducted under aseptic condition. The removal rate by immobilized microalgae is 0.040 mg/L/h for total ammonia and 1.97 x 10-3 mg/L/h for nitrite. The removal rate by blank alginate bead is 0.045 mg/L/h for total ammonia and 1.95 x 10-3 mg/L/h for nitrite. The removal efficiencies of nitrogenous compound by immobilized microalgae are no significant different between the application of blank alginate bead. This is because of bacteria activities that present in water and utilize nitrogen for their metabolism. However, there is positive grow of immobilized Nannochloropsis sp. in alginate bead (from 28.13 x 103 ceWml to 115.13 x 103 cell/ml). Photosynthesis of microalgae would contribute to increase dissolve oxygen in water. The application of immobilized microalgae not only to remove nitrogenous compound but also can stabilized the hydrological parameter in water. This technique is viable to control water quality in aquaculture.