A novel low cost microalgal harvesting technique with coagulant recovery and recycling.

In this study, a novel low cost and sustainable microalgal harvesting technique was developed using the concept of coagulant recovery concentration and recycling. Al can be recovered from harvested Scenedesmus acuminatus biomass with 0.1 M HCl, at an acid solution-biomass ratio of 250 ml g. The residual Al content in the purified biomass was reduced to 0.11 ± 0.0006 mg g, while a higher content of 59.74 ± 3.11 mg g was found in the coagulation harvested biomass. The recovered Al solution was concentrated 25 times and then reused for the harvesting of S. acuminatus. The Al recovery and reuse were repeated 5 times, and the harvesting efficiencies were found higher than the fresh Al as a result of the presence of extracellular polymeric substances in the recovered coagulant solution which aided the coagulation process. According to the technical-economic analysis, the cost of chemicals decreased 50% after 5 times recycling.