Simultaneous removal of inorganic nutrients and organic carbon by symbiotic co-culture of Chlorella vulgaris and Pseudomonas putida

The co-culture system of photosynthetic microalgae Chlorella vulgaris and aerobic heterotrophic bacteria Pseudomonas putida was investigated as a possible combination of symbiotic mixed culture for the simultaneous removal of nutrients (ammonium and phosphate) and organic contaminants. Using synthetic municipal wastewater, the co-culture system exhibited symbiotic enhancement in the removal of nutrients and organic carbon compared to each of axenic cultures. The co-culture system performed successfully in removing both of ammonium and chemical oxygen demand (COD), showing around 80% removal for 4 days. Strategies of nitrogen and phosphorous starvation in C. vulgaris for two days prior to main treatment did not increase the performance of nutrients removal, indicating that the nutrient starvation as a pretreatment is unnecessary. Without alkalinity (as bicarbonate), nutrients and COD were not removed significantly, implying that the existence of alkalinity is essential for symbiotic treatment of both nutrients and organics. Results demonstrated that coculture system composed of C. vulgaris and P. putida can be a potential candidate of mixed culture system for the simultaneous removal of nutrients and organic carbon in wastewater treatment using a single reactor.