Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São-Carlense, 400, 13566-59, São Carlos, São Paulo, Brazil E-mail:
Water Sci Technol. 2020 Sep;82(6):1227-1236. doi: 10.2166/wst.2020.106.
Microalgae harvesting is a major hurdle for the production of high-value microalgal bioproducts on a large scale. Among harvesting techniques, pH-induced sedimentation stands out as an inexpensive and technically viable method. Nevertheless, there is little information available on the application of this method for microalgae cultivated in wastewater. In this context, the present study investigated the optimization of sedimentation parameters for Chlorella sorokiniana harvesting from wastewater. Parameter optimization was statistically determined by the response surface methodology. The optimal values included a velocity gradient of 250 s, mixing time of 10 seconds, and pH of 12, which enabled microalgae harvesting efficiencies of more than 97.8%. These optimal parameters also showed resilience through the physico-chemical variation of the photobioreactor effluent. Furthermore, wastewater quality improved significantly after microalgae harvesting. High removal was found for turbidity (97.9-98.3%), apparent color (92.2-97.2%), total Kjeldhal nitrogen (91.0-94.4%), and total phosphorus (92.8-98.6%). Centrifugation, as the dewatering method, and its operational parameters were also evaluated. Sedimentation followed by centrifugation increased the initial microalgae concentration by about 123 times. This study shows the importance of operational optimization and the results can be used as practical guidelines for microalgae harvesting on a large scale.
微藻收获是大规模生产高价值微藻生物制品的主要障碍。在各种收获技术中，pH 诱导沉淀作为一种廉价且技术可行的方法脱颖而出。然而，关于该方法在废水培养的微藻中的应用，相关信息却很少。在这种情况下，本研究探讨了从废水中收获聚球藻的沉淀参数优化。通过响应面法对参数优化进行了统计学确定。最佳值包括速度梯度为 250 s、混合时间为 10 秒和 pH 值为 12，这使得微藻的收获效率超过 97.8%。这些最佳参数还通过光生物反应器流出物的物理化学变化表现出了良好的适应性。此外，微藻收获后废水质量显著改善。浊度（97.9-98.3%）、表观颜色（92.2-97.2%）、总凯氏氮（91.0-94.4%）和总磷（92.8-98.6%）的去除率很高。还评估了离心作为脱水方法及其操作参数。沉淀后离心使初始微藻浓度增加了约 123 倍。本研究表明了操作优化的重要性，研究结果可作为大规模微藻收获的实用指南。
