Microalgae–bacteria consortium treatment technology for municipal wastewater management

Abstract

The discharge of inadequately treated municipal wastewater in the developing countries is the major cause of environmental pollution in urban areas. However, the effort was made to minimize this burden using conventional wastewater treatment methods that require high capital and operational costs and are not affordable. Researchers are still looking for the cost-effective, efficient and environmentally compatible wastewater treatment technologies. Hence, this study aimed to investigate the potential of native microalgae–bacteria consortia for the removal of nutrient and organic pollutants from primary-treated municipal wastewater. Microalgae–bacteria treatment system was established by combining pre-cultured native algae consortia dominated by Chlorella sp., Chlamydomonas sp. and Scenedesmus sp. of the class Chlorophyceae with naturally existing municipal wastewater bacteria. Microalgae–bacteria culture acclimatization was performed and the actual experiment was carried out at 18% culture to wastewater by volume in photobioreactor at a light intensity of 120 μE/m2s. The maximum removal of TKN 69%, TP 59%, PO43−_ P 73%, COD 84% and BOD5 85% was observed in the combined treatment system, whereas for bacteria stand-alone treatment system, the maximum removal of TKN 31%, TP 56%, PO43−_ P 50%, COD 44% and BOD5 52% was recorded. Statistically significant differences were observed for the removal of NH3–N, TKN and PO43−_ P at p < 0.05 but statistically insignificant differences were observed for TP, COD and BOD5 in the combined treatment system. The study results suggest that the native microalgae consortia identified in the local environment can effectively reduce organic and nutrient pollutants from the primary-treated municipal wastewater. Generally, the performance evaluation of combined microalgae–bacteria treatment technology was efficient in municipal wastewater management and promising to scale up at industrial level.