Abstract
Inorganic arsenic (As) is one of the most significant chemical contaminants in drinking water worldwide. Although membrane-based technologies are commonly used for As removal, they often encounter challenges including complex operation, high energy consumption, and the need for chemical addition. To address these challenges, we proposed a one-step ultrafiltration (UF) process empowered by in situ biogenic manganese oxides (BioMnOx) cake layers without any additional chemicals, to treat source water contaminated with both As and manganese (Mn). During the filtration, BioMnOx continuously generated on the membrane surface with the oxidation of Mn2+ by Mn-oxidizing bacteria. The in situ generated BioMnOx cake layer exhibited a heterogeneous structure, high specific surface area, and significant catalytic activity. Notably, with this BioMnOx cake layer, the one-step UF successfully achieved a nearly 100% removal of As(III). This high efficiency is due to the catalytic oxidation of As(III) to As(V) by BioMnOx, followed by the adsorption of As(V) onto the BioMnOx surface. With the removal of Mn2+, new BioMnOx was continuously formed, which provided new catalytic and adsorption sites, thereby enabling a self-sustained removal of As(III). In addition to the advantages of simple operation and chemical free, the process also exhibited a good economic feasibility with a low energy consumption (0.078 kWh/m3) and a low operating cost (0.229 CNY/m3). Our study provides an example to show that cake layers on membranes are not inherently detrimental and can be beneficial in specific applications.
Published Version
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