Impact of copper sulphate, potassium permanganate, and hydrogen peroxide on Pseudanabaena galeata cell integrity, release and degradation of 2-methylisoborneol

Abstract

Frequent off-flavor events caused by geosmin and 2-methylisoborneol have caused concern among consumers about the quality of potable water. Pseudanabaena galeata, a filamentous cyanobacterium, is a known producer of 2-methylisoborneol in lakes and reservoirs. The use of algicides to control cyanobacteria must consider the potential release of contaminants into the water. This is the first study to systematically investigate the effectiveness of copper sulphate (CuSO4), potassium permanganate (KMnO4), and hydrogen peroxide (H2O2) on the cell viability and integrity of Pseudanabaena galeata. Following algicide or oxidant treatment, the release and degradation of 2-methylisoborneol was also examined. It is evident that all of these chemicals can decrease Pseudanabaena galeata viability and damage cell membranes and the filamentous Pseudanabaena galeata was more susceptible to treatment by these three algicides than unicellular colonial Microcystis aeruginosa. Of the three compounds used, KMnO4 showed the stronger ability to compromise cell integrity and 5.0 mg/L KMnO4 could induce 91 ± 1.5% lysis of Pseudanabaena galeata within 2 h. It was found that H2O2 had the potential to degrade 2-methylisoborneol with 16.0 ± 0.4% degraded by 20.0 mg/L H2O2 within 8 h. In contrast, 2-methylisoborneol could not be degraded by CuSO4 (dosage: ≤ 1.5 mg/L; reaction time: ≤ 8 h) and KMnO4 (dosage: ≤ 5.0 mg/L; reaction time: ≤ 3 h) basically. Results showed that the oxidation capacity of H2O2 against Pseudanabaena galeata was enhanced under sunlight. The results will help drinking water utilities to better understand the risk of Pseudanabaena galeata lysis and 2-methylisoborneol release during raw water treatment.