A bacterial strain Citrobacter W4 facilitates the bio-flocculation of wastewater cultured microalgae Chlorella pyrenoidosa

Jiawen He; Wanqing Ding; Wei Han; Yidi Chen; Wenbiao Jin; Xu Zhou

doi:10.1016/j.scitotenv.2021.151336

A bacterial strain Citrobacter W4 facilitates the bio-flocculation of wastewater cultured microalgae Chlorella pyrenoidosa

Sci Total Environ. 2022 Feb 1;806(Pt 3):151336. doi: 10.1016/j.scitotenv.2021.151336. Epub 2021 Oct 29.

Authors

Jiawen He¹, Wanqing Ding¹, Wei Han¹, Yidi Chen¹, Wenbiao Jin², Xu Zhou³

Affiliations

¹ State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
² State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China. Electronic address: jinwb@hit.edu.cn.
³ State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China. Electronic address: zhouxu@hit.edu.cn.

PMID: 34743821
DOI: 10.1016/j.scitotenv.2021.151336

Abstract

A bacteria strain Citrobacter W4 isolated from the microalgae sewage culture system showed flocculating activity against Chlorella pyrenoidosa. In this work, operation parameters under outdoor conditions were optimized. When the bacterial-algal ratio was 4:1, G value was 26.30 s^-1, and harvesting time was 6 h, the harvesting efficiency achieved 87.37 ± 2.96% without ions addition and pH adjustment. The microbial community structure analysis showed Citrobacter W4 was dominant in the harvesting process. Flocculating active substances were on the surface and metabolites of Citrobacter W4. The main component of bacteria flocculating active substances was protein. Polysaccharides and carboxylic acid also promoted flocculation. The flocculation mechanisms were mainly adsorption bridging, net catching, and sweeping, not electric neutralization. The quality of FAMEs was improved after flocculation. The cost of 1 kg dried microalgae flocculated by Citrobacter W4 was $1.35. The novel flocculating bacteria showed the potential to harvest microalgae cost-effectively and environmentally friendly.

Keywords: Bacteria; Bio-flocculation; Flocculation mechanism; Microalgae harvesting; Wastewater.

MeSH terms

Bacteria
Biomass
Chlorella*
Citrobacter
Flocculation
Microalgae*
Wastewater

Substances

Waste Water