Influence of pH on bioclogging in porous media during managed aquifer recharge (MAR): Effectiveness and mechanism

To investigate the effect of pH on bioclogging process during managed aquifer recharge, three laboratory-scale column experiments were conducted and the relative hydraulic conductivity, bacterial cell number and the concentrations of polysaccharide, protein and EPS were measured under pH 5, 7, and 9, respectively. Highthroughput sequencing was also used to determine the characteristics of bacterial community under different pH conditions. The development of bioclogging was rather different for the case of pH 5. 7, and 9; i.e., the growth process and number of bacteria differed with pH. The shortest growth period and lowest number of bacteria were observed at pH 5. In addition, the difference in bacterial EPS concentration was mainly associated with the polysaccharides. The variation in pH led to different bacterial community composition and diversity. The acidresistant Elizabethkingia and Bacillus were abundant at pH 5, while Chryseobacterium and Klebsiella had relatively high abundances at pH 7. In contrast, the basophilic Exiguobacterium accounted for >80% of the total bacterial abundance at pH 9. This work is of great significance to explore bioclogging mechanism during MAR process, and provides insights and guidances for field-based managed aquifer recharge.