Algae harvesting for biofuel production: Influences of UV irradiation and polyethylenimine (PEI) coating on bacterial biocoagulation

• Published in: Bioresource technology 2014-08, Vol.166, p.266-272
• Main Authors: Agbakpe, Michael, Ge, Shijian, Zhang, Wen, Zhang, Xuezhi, Kobylarz, Patricia
• Format: Article
• Language: English
• Subjects: Algae; Algal harvesting; Bacteria; Barriers; Biocoagulation; Biofuel; Biofuel production; Biofuels - microbiology; Biological and medical sciences; Biotechnology; Chlorella - growth & development; Chlorella - isolation & purification; Chlorella - metabolism; Chlorella zofingiensis; Coagulation efficiency; DLVO; Energy; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - metabolism; Escherichia coli - radiation effects; Flocculation - drug effects; Flocculation - radiation effects; Fuels; Fundamental and applied biological sciences. Psychology; Harvesting; Industrial applications and implications. Economical aspects; Irradiation; Polyetherimides; Polyethyleneimine - pharmacology; Polyethylenimine; Rhodococcus - drug effects; Rhodococcus - metabolism; Rhodococcus - radiation effects; Scenedesmus - growth & development; Scenedesmus - isolation & purification; Scenedesmus - metabolism; Scenedesmus dimorphus; Ultraviolet Rays
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.05.060

[Display omitted] •PEI coating on bacteria dramatically enhanced the algal harvesting efficiency.•UV365 irradiation could also improve the biocoagulation process.•Potential energy barrier exists between the interacting bacterial and algal cells. There is a pressing need to develop efficient and sustainable separation technologies to harvest algae for biofuel production. In this work, two bacterial species (Escherichia coli and Rhodococus sp.) were used as biocoagulants to harvest Chlorella zofingiensis and Scenedesmus dimorphus. The influences of UV irradiation and polyethylenimine (PEI)-coating on the algal harvesting efficiency were investigated. Results showed that the UV irradiation could slightly enhance bacteria–algae biocoagulation and algal harvesting efficiency. In contrast, the PEI-coated E. coli cells noticeably increased the harvesting efficiencies from 23% to 83% for S. dimorphus when compared to uncoated E. coli cells. Based on the soft-particle Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, an energy barrier existed between uncoated E. coli cells and algal cells, whereas the PEI coating on E. coli cells eliminated the energy barrier, thereby the biocoagulation was significantly improved. Overall, this work presented groundwork toward the potential use of bacterial biomass for algal harvesting from water.