Mechanism of biofilm formation on a hydrophobic polytetrafluoroethylene membrane during the purification of surface water using direct contact membrane distillation (DCMD), with especial interest in the feed properties

Abstract

The impact of feed water quality on biofilm formation during membrane distillation (MD) was investigated in this study, particularly emphasizing the interrelationship between organics, salts, and microbes. Two types of typical natural surface waters in Nanjing, China, were chosen as feed solutions for long-term MD operation, including the Qinhuai River and Xuanwu Lake. The biofilms that developed under different feed water qualities exhibited distinct Foulant compositions and structures, causing different flux decline trends for the MD system. Accordingly, two typical patterns of biofilm formation were suggested for the MD operation of the two different kinds of surface waters in this study. Organics from a primal feed solution and dead bacteria were the key to the establishment of a biofilm on the membrane, and this needs to be effectively removed from the MD system through pre-treatment and process control strategies. Finally, a feasible strategy for MD biofouling control was suggested.

Keywords:

• Membrane distillation
• surface water treatment
• feed water quality
• biofouling
• biofilm structure
• microbial community composition

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The Fundamental Research Funds for the Central Universities (grant number: 2019B80914), the Postgraduate Research & Practice Innovation Program of Jiangsu Province, and the Fundamental Research Funds for the Central Universities (grant number: 2018B15014) provided funds for this study.