Insight into the microbial distribution and succession and biofouling mechanism in membrane distillation for desulfurization wastewater treatment

The unrevealed mystery of biofouling obfuscates the understanding of fouling mechanism and the commercial application of Membrane distillation (MD). In this study, biofouling was revealed with respect to microbial morphology, distribution, succession, and function in MD for desulfurization wastewater. Heat- and salinitystress driven the reconstruction of microbial community with a decrease in diversity, activity, and motility. Idiomarina and Phenylobacterium were enriched on membrane for higher cell motility and degradation ability. Horizontal distribution appeared with rising fouling tendency and longer but thinner cells, result from the Concentration polarization (CP), heat-, flow-, and nutrient-stress. Vertically, bacteria with higher motility, secretory ability, and activity like Chelativorans, Acinetobater, Salinarimonas attached to membrane surface firstly. Then pioneering bacteria with low microbial biosynthesis and cellular process but high degradation ability accumulated in the bottom layer, driven the DOM transformation for higher tryptophan and tyrosine metabolism. CP was a key reason for the accumulation of upper layer, in where the bacteria had low cellular process and motility. This work reveals the microbial succession and biofouling formation process, which provides an indepth information to fill the knowledge gap of MD biofouling.