Microalgal wastewater recycling: Suitability of harvesting methods and influence on growth mechanisms

• Published in: The Science of the total environment Vol. 859; no. Pt 2; p. 160237
• Main Authors: Sun, Jingjing, Jiang, Shuhong, Yang, Libin, Chu, Huaqiang, Peng, Bo-Yu, Xiao, Shaoze, Wang, Yayi, Zhou, Xuefei, Zhang, Yalei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.02.2023
• Subjects: Biomass; Centrifugation; Flocculation; Flocculation sedimentation; Microalgae; Microalgae harvesting; Microfiltration; Phytohormone; Recycling; Wastewater; Wastewater recycling; ABA; TDS; tZ; Centrifugation; IP; Flocculation sedimentation; IAA; CK; SOD; TOC; MW; MDA; Microalgae harvesting; AGR; EEM; SA; FW; Microfiltration; CW; Wastewater recycling; JA; IPA; Phytohormone; AOM
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.160237

Wastewater recycling helps address the challenge of microalgae biomass commercialization by allowing for efficient resource recovery. In this study, three conventional harvesting methods, including centrifugation, microfiltration, and flocculation sedimentation, were investigated to explore the effects of harvesting methods on the characteristics of recycled wastewater and the growth of microalgae to select a suitable harvesting method for the microalgal wastewater recycling system. During the wastewater recycling process, the least amount of accumulated substances was exhibited in the wastewater recycled by microfiltration, followed by centrifugation, and the most by flocculation sedimentation. After 4 batches of cultivation, microalgal biomass harvested from centrifugation wastewater and microfiltration wastewater was 21.26 % and 13.54 % higher than that from flocculation wastewater, respectively. Lipids, carbohydrates and pigments were all increased by varying degrees. Additionally, flocculation sedimentation was not suitable for the microalgal wastewater recycling process since the low residual nutrients, high salinity, and excessive algal organic matter severely inhibited the growth of microalgae. Under the regulation of phytohormones, microalgae increased their energy reserves, enhanced photosynthesis, and improved their defense capability to resist the increasing abiotic stress. This study provides scientific support for the selection of suitable harvesting technology during the microalgal wastewater recycling process. [Display omitted] •Microalgal biomass harvest from recycled wastewater followed the order of CW > MW > FW.•MW accumulated the least amount of substances during the recycling process.•Harvesting method affect the accumulation of phytohormones.•Algae enhance energy reserve, photosynthesis and oxidation defense to resist stress.•FW is low in nutrients, high in salinity, and excessive in AOM.