Ma Xiaochen, Zheng Hongli, Zhou Wenguang, Liu Yuhuan, Chen Paul, Ruan Roger
Institute of Microbiology, Chinese Academy of Sciences, A3 Datun Road, Chaoyang District, Beijing, 100101, People's Republic of China.
Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN, 55108, USA.
Appl Biochem Biotechnol. 2016 Oct;180(4):791-804. doi: 10.1007/s12010-016-2133-5. Epub 2016 May 20.
In this study, a novel flocculation strategy for harvesting Chlorella vulgaris with combined flocculants, poly (γ-glutamic acid) (γ-PGA) and calcium oxide (CaO), has been developed. The effect of flocculant dosage, the order of flocculant addition, mixing speed, and growth stage on the harvesting efficiency was evaluated. Results showed that the flocculation using combined flocculants significantly decreases the flocculant dosage and settling time compared with control. It was also found that CaO and γ-PGA influenced microalgal flocculation by changing the zeta potential of cells and pH of microalgal suspension. The most suitable order of flocculant addition was CaO first and then γ-PGA. The optimal mixing speed was 200 rpm for 0.5 min, followed by 50 rpm for another 4.5 min for CaO and γ-PGA with the highest flocculation efficiency of 95 % and a concentration factor of 35.5. The biomass concentration and lipid yield of the culture reusing the flocculated medium were similar to those when a fresh medium was used. Overall, the proposed method requires low energy input, alleviates biomass and water contamination, and reduces utilization of water resources and is feasible for harvesting C. vulgaris for biofuel and other bio-based chemical production.
在本研究中，开发了一种使用复合絮凝剂聚（γ-谷氨酸）（γ-PGA）和氧化钙（CaO）收获普通小球藻的新型絮凝策略。评估了絮凝剂用量、絮凝剂添加顺序、混合速度和生长阶段对收获效率的影响。结果表明，与对照相比，使用复合絮凝剂进行絮凝可显著降低絮凝剂用量和沉降时间。还发现CaO和γ-PGA通过改变细胞的zeta电位和微藻悬浮液的pH值影响微藻絮凝。最合适的絮凝剂添加顺序是先加CaO，然后加γ-PGA。对于CaO和γ-PGA，最佳混合速度为200 rpm，持续0.5分钟，然后为50 rpm，再持续4.5分钟，絮凝效率最高可达95%，浓缩系数为35.5。重复使用絮凝后培养基的培养物的生物量浓度和脂质产量与使用新鲜培养基时相似。总体而言，所提出的方法所需能量输入低，可以减轻生物质和水污染，减少水资源利用，对于收获普通小球藻用于生物燃料和其他生物基化学品生产是可行的。
