Removal of Natural Organic Matter Fractions by Kaolin/Fly Ash Ceramic Microfiltration Membrane in Drinking Water: Insights from a Laboratory Scale Application

Abstract

The high cost of precursor materials has hindered commercialization of ceramic membranes (CM). In this work, a microfiltration ceramic disc (≈50 mm in diameter and 4 mm thick) is prepared from low-cost materials, kaolin, and fly ash (≈67 and 26 wt.%, respectively) by pressing at 200 bar and calcining at 900 °C. Membrane characterization involved physicochemical properties, NOM removal efficiency, and fouling propensity analysis. Furthermore, the efficiency of the CM is tested on samples collected from four drinking water treatment plants (DWTPs) in KwaZulu-Natal Province of South Africa. The NOM removal efficiencies ranged from 18.5–33.4% higher than that achieved by the sand filtration step of all the DWTPs. Fluorescence excitation-emission matrix (FEEM) studies show dominance of terrestrial humic-like and fulvic-like NOM fractions in the raw water and are amenable to removal by CM at all the DWTPs (up to 64.7% higher than removal by sand filters at the respective plants). This study demonstrates the utility of ceramic membranes fabricated from rudimentary materials and presents an opportunity to upscale and retrofit the technology to target the removal of NOM fractions at conventional drinking water treatment plants.