Biofouling in ultrafiltration process for drinking water treatment and its control by chlorinated-water and pure water backwashing

• Published in: The Science of the total environment 2018-12, Vol.644, p.306-314
• Main Authors: Shao, Senlin, Wang, Yue, Shi, Danting, Zhang, Xuezhi, Tang, Chuyang Y., Liu, Zizheng, Li, Jiangyun
• Format: Article
• Language: English
• Subjects: Ammonia; Backwashing; Biofouling; Drinking water treatment; Membranes, Artificial; Ultrafiltration; Water; Water Purification - methods
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.06.220

We investigated biofouling in ultrafiltration (UF) for drinking water treatment and its control by backwashing with chlorinated-water or pure water. By using sodium azide to suppress biological growth, the relative contribution of biofouling to total fouling was estimated, and its value (5.3–56.0%) varied with the feed water, and increased with the increases of filtration time and membrane flux. The biofouling layer could partially remove biodegradable organic matter and ammonia (32.9–74.2%). Backwashing using chlorinated-water partly inactivated the microorganisms (23.8%) but increased the content of extracellular polymeric substances (7.7%) in the biofouling layer. In contrast, backwashing using pure water led to a looser and more porous fouling layer according to optical coherence tomography observation. Consequently, the latter was more effective in reducing fouling resistance (33.41% reduction) compared to backwashing by chlorinated-water (8.6%). These findings reveal the critical roles of biofouling in pollutants removal in addition to membrane permeability, which has important implications for addressing seasonal ammonia pollution. [Display omitted] •Biofouling accounted for 5.3–56.0% of the total fouling in the UF process for drinking water treatment.•Biofouling layer could partially remove biodegradable organic matter and ammonia.•Backwashing with pure water is an effective way for biofouling control.