Optimal Conditions for the Treatment of Shrimp Culture Effluent Using Immobilized Marine Microalga Picochlorum maculatum (PSDK01)

A significant environmental concern has been raised over the wastewater produced from aquaculture including shrimp farms. In order to evaluate the potential of microalgae to treat the wastewater from a shrimp aquaculture, response surface methodology (RSM) was applied to identify optimal conditions for various parameters. Picochlorum maculatum immobilized beads were used to remove excessive nutrients (phosphate, nitrate, nitrite and ammonia) from a 90 days old shrimp ( Litopenaeus vannamei ) cultured wastewater. The effects of number of algal cells per bead, density of beads per given volume of wastewater, pH, and retention time were investigated. A significant maximum nutrient removal was obtained at pH 7, 24 h of retention time, 150 beads of density and 111,200 cells/ml of algal cell concentration. The primary experimental results were used to RSM for optimizing the variables statistically for maximum nutrient removal. A ‘minimum run resolution V’ central composite design with four variables (pH and retention time, different bead density and algal cell concentrations in beads) was applied to optimize the process. The results showed good fits with the proposed statistical model for the removal of nutrients.