Efficiency of Nannochloropsis oculata and Bacillus polymyxa symbiotic composite at ammonium and phosphate removal from synthetic wastewater.

Many issues, such as, DO accumulation, N2 fixation obstacle, and carbon dioxide diffusion, hamper the application of microalgae-alginate immobilization in wastewater treatment. The objective of this study was to evaluate the effect of the microalgae Nannochloropsis oculata immobilized with the bacterium Bacillus polymyxa in alginate on ammonium and phosphate removal from synthetic wastewater. Results show that the co-immobilized Bacillus-Nannochloropsis can exploit ammonium and phosphate from wastewater more effectively than the immobilized Nannochloropsis, and immobilized Bacillus alone. A significantly higher ammonium and phosphate removal efficiency was found in co-immobilized Bacillus-Nannochloropsis (59.85%, 90.44%) than of that in immobilized Nannochloropsis (49.56%, 77.36%), and Bacillus immobilized (31.46%, 29.66%) alone. Additionally, the most effective co-immobilization mixture ratio for wastewater treatment was found to contain equal suspension (108 cell/ml) volume of the Nannochloropsis and Bacillus. Nannochloris and Bacillus can coexist harmoniously with the symbiotic and synergistic relationship, and the Nannochloropsis oculata- Bacillus polymyxa combination can be useful as a potential method to develop novel wastewater treatment.