Direct removal of harmful cyanobacterial species by adsorption process and their potential use as a lipid source

In the present study, we applied an adsorption process to remove and recover the harmful pollutant Microcystis aeruginosa using a polyethyleneimine (PEI)-modified chitosan-waste biomass composite fiber (PEI-CBF). The enhancement of positive binding sites on the sorbent after PEI modification is an important factor in ensuring the removal potential of the adsorption processing for M. aeruginosa cell removal from an aqueous solution. PEI-CBF could remove 91.2% of M. aeruginosa cells without additional processing, while the chitosan-biomass composite fiber (CBF) removed 22.7% under the same experimental conditions. In the cell removal process using PEI-CBF, the M. aeruginosa cells were bound to the PEI-CBF without cell lysis or damage. From the cell-loaded PEI-CBF, 95.3% of the adsorbed cyanobacterial cells were recovered via a desorption process in an alkaline solution and ultrasonication. In addition, the total lipid content of the recovered M. aeruginosa cells was similar to that of centrifuged M. aeruginosa cells. Furthermore, the cell removal performance of regenerated PEI-CBF was almost entirely maintained. Our adsorption process can be applied as a novel technology to allow the conversion of the environmental pollutant M. aeruginosa into energy resources by recovering and controlling cells without substrate loss by cell lysis.