Contribution of filtration and photocatalysis to DOM removal and fouling mechanism during in-situ UV-LED photocatalytic ceramic membrane process

Chen Li; Wenjun Sun; Zedong Lu; Xiuwei Ao; Simiao Li; Zhenbei Wang; Fei Qi; Oksana Ismailova

doi:10.1016/j.watres.2022.119298

Contribution of filtration and photocatalysis to DOM removal and fouling mechanism during in-situ UV-LED photocatalytic ceramic membrane process

Water Res. 2022 Nov 1:226:119298. doi: 10.1016/j.watres.2022.119298. Epub 2022 Oct 26.

Authors

Chen Li¹, Wenjun Sun², Zedong Lu³, Xiuwei Ao³, Simiao Li⁴, Zhenbei Wang⁵, Fei Qi⁵, Oksana Ismailova⁶

Affiliations

¹ Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; School of Environment, Tsinghua University, Beijing 100084, China.
² School of Environment, Tsinghua University, Beijing 100084, China; Research Institute for Environmental Innovation (Suzhou), Tsinghua, China. Electronic address: wsun@tsinghua.edu.cn.
³ School of Environment, Tsinghua University, Beijing 100084, China.
⁴ School of Environment, Tsinghua University, Beijing 100084, China; Beijing General Municipal Engineering Design and Research Institute Co. Ltd., Beijing China.
⁵ Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
⁶ Uzbekistan-Japan Innovation Center of Youth, Tashkent, Uzbekistan.

PMID: 36327584
DOI: 10.1016/j.watres.2022.119298

Abstract

The use of ceramic membranes and ultraviolet light-emitting diodes (UV-LEDs) has advanced the application of photocatalytic membrane for water treatment. We systematically evaluated the contribution of filtration and photocatalysis to dissolved organic matter (DOM) removal and fouling mechanism during in-situ UV-LED photocatalytic ceramic membrane filtration. The results showed that physical rejection primarily led to removal of 4-15 kDa molecules and photocatalysis further increased the removal of 1-4 kDa molecules, causing small sized microbial humic-like or protein-like materials in the permeate. In-situ UV-LED photocatalysis had an excellent effect on membrane fouling mitigation regardless of DOM sources. The dominant fouling mechanism changed from partial blockage to gel layer formation with increasing Ca²⁺ concentration but did not change with UV treatment. Correlation analysis revealed that the removal of 1-4 kDa molecules contributed to the mitigation of both reversible and irreversible fouling resistance, and the small molecules were the major cause of irreversible fouling resistance. Removal of 1-4 kDa terrestrial humic acid-like contributed to the pore blockage mechanism for synthetic water. Removal of 4-15 kDa protein-like materials was closely correlated to the pore blockage mechanism for real water. Trihalomethanes (THMs) and haloacetic acids (HAAs) formation potential (FP) were both significantly reduced after photocatalytic ceramic membrane process, but precursors of nitrogenous disinfection by-products (N-DBPs) with high toxicity were not removed by filtration or by photocatalysis, which deserves attention. Membrane rejection made higher contribution to better DBPFP control than photocatalysis. This study provides novel insights into the impact of UV-LED on DOM removal, DBPFP control and fouling mitigation, promoting the development of photocatalytic ceramic membrane filtration.

Keywords: Disinfection by-products; Dissolved organic matter; Membrane fouling; Photocatalytic ceramic membrane; UV-LED.

MeSH terms

Ceramics
Dissolved Organic Matter
Filtration
Membranes, Artificial*
Water Purification* / methods

Substances

Membranes, Artificial
Dissolved Organic Matter