Evaluation of ferrate (VI) for enhanced coagulation of algae-rich water: Mechanisms of Microcystis aeruginosa cell dehydration

Abstract

Algae and their derivatives in drinking water sources posed a serious threat to the safety of drinking water quality. The water content of collected algae should be reduced as much as possible in order to utilize algae resources. In this study, the M. aeruginosa during dehydration was characterized, and the effects of ferrate (VI) on the floc suspension and dehydration efficiency of algae cells were analyzed. The dehydration performance of M. aeruginosa was evaluated quantitatively from three different aspects: algal cell, flocs and sludge. The results shown that 5.0 mg/L was the preferred ferrate (VI) dosage which the removal rate of dissolved organic matter in the solution increased from 44.9 % to 86.2 %, the dehydration capacity of algae increased by 55.80 %. The mechanism of ferrate (VI) on algae dehydration was verified: the treatment of ferrate (VI) led to the transformation of B-EPS to S-EPS, thus the interstitial water between algae cells was reduced, the flocs was increased, and the solid content of algae-containing sludge was added, which promoted the optimization of algae-containing sludge dewatering performance. This method is helpful to the further study of algae dehydration and provides an idea for harmless dehydration.