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

Yang, Lin, Wang, Lan, Zhang, Haiyang, Li, Cheng, Zhang, Xuezhi, Hu, Qiang
Bioresource technology 2018 v.266 pp. 343-348
Scenedesmus, aluminum, biomass, coagulants, coagulation, harvesting, hydrochloric acid, microalgae, recycling
In this study, a novel low cost and sustainable microalgal harvesting technique was developed using the concept of coagulant recovery concentration and recycling. Al3+ can be recovered from harvested Scenedesmus acuminatus biomass with 0.1 M HCl, at an acid solution-biomass ratio of 250 ml g−1. The residual Al3+ content in the purified biomass was reduced to 0.11 ± 0.0006 mg g−1, while a higher content of 59.74 ± 3.11 mg g−1 was found in the coagulation harvested biomass. The recovered Al3+ solution was concentrated 25 times and then reused for the harvesting of S. acuminatus. The Al3+ recovery and reuse were repeated 5 times, and the harvesting efficiencies were found higher than the fresh Al3+ 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.