The long-term removal of dissolved Mn from drinking water via membrane filtration using sodium permanganate as a pre-oxidant

Abstract

Dissolved Mn, often found in water sources, can cause various problems such as discoloration, and poor taste and odor. In this study, the long-term removal of dissolved Mn via a membrane-filtration process using sodium permanganate (NaMnO4) as a pre-oxidant was evaluated for drinking water treatment. Thereby, 0.67 M NaMnO4 pre-oxidation for 10 min was optimal and removed 91% of the dissolved Mn from raw water. In addition, increasing the pH improved the removal efficiency, as did varying the temperature (83% to 89% for 5.1 to 25 °C). Additionally utilizing poly aluminum chloride as a coagulant helped to remove both dissolved Mn and organic matter from the water. Using NaMnO4 as a pre-oxidant also played a significant role in the membrane filter-based removal of dissolved Mn using both pressurized and submerged membrane filters over the long term. The results show that the average removal rate of dissolved Mn in the range of 0–0.039 mg/L via membrane-filtration processes with and without NaMnO₄ pre-oxidation was 19% and 92%, respectively. The removal rate by both membranes was similar while the increase in trans-membrane pressure was insignificant. Thus, NaMnO4 pre-oxidation coupled with membrane filtration is an enterprising solution for removing dissolved Mn from drinking water.