The study of green algae removal by potassium permanganate pre-oxidation enhanced coagulation
高锰酸钾预氧化强化混凝去除绿藻的研究

This study investigated the influence of permanganate oxidation on algae cell structure, zeta potential, extracellular organic matter molecular weight distribution and concentration, and explored the mechanisms of permanganate-enhanced chlorella algae removal by coagulation. When the dosage of permanganate was no more than 2 mg·L-1, the composition of organic matter in suspension kept unchanged and partial extracellular organic matter (EOM) was oxidized. At the beginning of oxidation, permanganate induced the release of EOM from the algae and thus increased the organic content in suspension. The zeta potential experienced an increase after a decrease while the algae activity was dropped by permanganate. However, the structure of algae kept complete and MnO2 produced after oxidation adhered to the algae surface which increased the algae density and favored the subsequent algal coagulation. When the concentration of permanganate was no less than 3 mg·L-1, the algal cell structure was destroyed, the high molecular intracellular organic matter was released into the algae suspension, and zeta potential decreased, all of which had negative effects on subsequent algal coagulation. The results showed that the optimal dosage of permanganate was 2 mg·L-1 and the optimum contact time for permanganate oxidation was 1 h. Permanganate pre-oxidation could enhance algae removal by coagulation with PAC significantly.