Fabrication of Catalytic Membranes for the Treatment of Drinking Water Using Combined Ozonation and Ultrafiltration

TLDR

The study investigated the removal of disinfection byproducts and their precursors using a combined ozonation–ultrafiltration system. A commercial ultrafiltration membrane was coated 20–40 times with 4–6 nm iron oxide nanoparticles, and ozone decomposition at the coated surface generates hydroxyl or other radicals that enhance natural organic matter degradation. The coated membranes reduced dissolved organic carbon by >85 % and total trihalomethanes and haloacetic acids by up to 90 % and 85 %, respectively, and lowered aldehydes, ketones, and ketoacids by >50 % compared with uncoated membranes; increasing coating repetitions had little effect on most parameters but decreased ozonation byproducts, and raising the sintering temperature from 500 °C to 900 °C further improved ozonation byproduct removal.

Abstract

The removal of disinfection byproducts and their precursors was investigated using a combined ozonation−ultrafiltration system. A commercial membrane was coated 20 or 40 times with iron oxide nanoparticles (4−6 nm in diameter). With this membrane, the concentration of dissolved organic carbon was reduced by >85% and the concentrations of simulated distribution system total trihalomethanes and simulated distribution system halo acetic acids decreased by up to 90% and 85%, respectively. When the coated membrane was used, the concentrations of aldehydes, ketones, and ketoacids in the permeate were reduced by >50% as compared to that obtained with the uncoated membranes. Hydroxyl or other radicals produced at the iron oxide coated membrane surface as a result of ozone decomposition are believed to have enhanced the degradation of the natural organic matter, thereby reducing the concentration of disinfection byproducts. While increasing the number of times the membrane was coated from 20 to 40 did not significantly reduce the concentrations of most of the parameters measured, it did result in a significant decrease in the concentrations of ozonation byproducts. Increasing the sintering temperature from 500 to 900 °C also resulted in an improvement in the removal of the ozonation byproducts.