Flocculation-based methods of microalgae removal from the eutrophic pond enrichment culture

Abstract

The method of flocculation of biomass from the water depth to the bottom can be applied in case of local algae blooms. In our research, the combined application of FeCl3 and Polyethyleneoxide-based cationic flocculant was applied for the first time for the harvesting of the enrichment culture obtained from the reservoir during eutrophication. The effects of coagulant (FeCl3·6H2O), various flocculants based on polyacrylamide (PAA), polyethylenoxide (PEO) and flocculated biomass as ballast agent, dosage and sedimental time on flocculation efficiency of harvesting enrichment culture obtained from Pond Chernoistochinsky during eutrophication have been studied. The results show that the flocculation efficiency achieved about 90% after 5 min of sedimentation when adding coagulant and flocculant mixture (FeCl3 30 mg/L + PEO based Sibfloc-718 2.5 mg/L) or flocculant with ballast agent (FeCl3 30 mg/L + Sibfloc-718 2.5 mg/L + 1,7% flocculated biomass). PAA, PEO and FeCl3·6H2O did not demonstrate a sufficient flocculation capacity with enrichment culture containing different types of microalgae. HIGHLIGHTS Combined application of FeCl3 and polymeric flocculant was successfully applied for sedimentation of enrichment culture obtained from an eutrophic pond.; The use of flocculants has been shown to be a promising method of biomass concentration in water bodies.; Application of flocculated biomass as ballast agent for further biomass flocculation was shown to be effective.;

Keywords

• ballast
• eutrophication
• flocculation
• harvesting of biomass
• inorganic coagulants
• polymeric flocculants