Evaluation of the potential of four microalgal-bacterial symbiotic association on wastewater treatment and lipid accumulation

Microalgae-bacteria symbiotic systems have demonstrated greater benefits over the pure culture of microalgae. The existence of certain bacteria will increase the quality of sewage purification and also reduce the associated high capital cost for maintaining the pure culture of microalgae. In this study, the potential of four microalgal-bacterial symbiotic associations to accumulate lipid besides growth rate, biomass concentration, and to eliminate nutrients from secondary treated municipal wastewater was evaluated. The two microalgae strains, namely, Tetraselmis indica, Chlorella protothecoide in combination with Pseudomonus sp. and Bacillus pumilus were observed. Chlorella protothecoide-Pseudomonas sp. system achieved the highest lipid productivity of 37.93 ± 2.53 mg L-1d-1 with lipid content 25.67 ± 0.95 % after ten days of cultivation. The chlorophyll-a content of Chlorella protothecoide + Pseudomonas sp. has 32% higher than the pure Chlorella protothecoide culture in wastewater. On the 10th day, Chlorella protothecoide-Pseudomonas sp. system removed 83.59 %, 86.76%, and 81.35% of chemical oxygen demand (COD), total dissolved nitrogen (TDN), and total dissolved phosphorus (TDP), respectively. Chlorella protothecoide + Pseudomonas sp. could coexist as a consortium has the potential to be utilized in biofuel technology.