Ancient terminal water treatment methods still work: Removing micropollutants in drinking water by simultaneous boiling and VUV

Abstract

Micropollutant in drinking water may not be effectively removed during centralized treatment. To reduce potential health risks, water treatment at the user terminal is warranted. This study investigated the performance of VUV coupled with boiling to simultaneously remove contaminants, a common household water treatment method in developing countries, for the treatment of micropollutants. Compared to individual boiling or VUV treatment, the VUV/BO process was more effective in improving the degradation of micropollutants. The results showed that heating promoted the direct photolysis and HO oxidation capabilities in the VUV process, with the HO generation increasing from 36.56 μM at 30 °C to 80.48 μM at 90 °C. At a reaction temperature of 100 °C, the degradation rates of malathion (MAL), dimethoate (DMT), trichloroacetic acid (TCAA), and dichloroacetic acid (DCAA) by VUV were increased by 0.81, 1.19, 1.34, and 0.90 times respectively compared to 25 °C. Analysis of the organic composition of actual water samples showed that the total fluorescence intensity of organic matter decreased significantly after VUV oxidation, mainly degrading humic-like substances. Using GC–MS analysis, this study identified 11 oxidative products of the DMT, and proposed two possible degradation pathways. Toxicity evaluation of the intermediate products of DMT demonstrated that they were less toxic than the parent contaminants. The results indicate that the heating-coupled water treatment process provides an effective technology for the treatment of micropollutants in terminal drinking water, and this process is worth promoting in the future.