Algae-based sustainable approach for simultaneous removal of micropollutants, and bacteria from urban wastewater and its real-time reuse for aquaculture

Freshwater consumption by humans has reached its peak, magnifying a dearth to freshwater availability across the world. The rising demand for freshwater has led to an interest in using purified wastewater for reuse. In this study, a novel microalgal strain Pseudochlorella pringsheimii — Ind-Jiht-1 was assessed in a pilot-scale for phyco-mitigation of various pollutants in the raw urban wastewater, including heavy metals as well as antibiotics resistant bacteria. The results appeared promising; the technology achieved an 83.2% reduction in COD, 66.7% in alkalinity and 69.6% in hardness. Moreover, almost complete reductions in total bacterial and total coliforms could be achieved. Three isolates viz., IS-2, IS-9 and IS-10, which were in the raw wastewater, could be obtained even after the 14-days microalgal-treatment of the wastewater. IS-2 was the most dominating bacterial species and able to thrive in urban wastewater even after the treatment. The treated wastewater was used to cultivate the sucker fishes. Bodyweight of the fishes was measured for evaluating their growth rates. The average survival rates of the sucker fish in the raw wastewater and treated wastewater were 0% and 84%, respectively. Results confirm that the algae-based technology not only reduces the micropollutants and bacteria from urban wastewater but also offers a platform for reuse of treated water for low-cost fish cultivation.