Microbial communities and relationship with biofilm spatial distributions in subsurface wastewater infiltration systems

A pilot-scale subsurface wastewater infiltration system (SWIS) was designed for the treatment of polluted river water. The components of microbial communities have been identified and characterized and their dependences on some indicators of biofilm formation in the SWIS have been determined. The average efficiencies of COD, TN and removal were 43.3%, 28.8% and 79.6%, respectively. According to the denaturing gradient gel electrophoresis (DGGE) profile, high intensity and uniform bands were generated, indicating an abundant microbial community in each layer of the SWIS. Furthermore, the Shannon index analysis showed high correlation to the spatial distribution of microbial communities as well as the quantity of biofilm in each sample, which were characterized by measuring volatile suspended solids (VSS), phospholipids, proteins and polysaccharides. Sequencing of partial 16S rRNA gene fragments revealed that the composition of the total bacterial communities was dominated by Alphaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Pseudomonas, Bacillus, Flavobacteriaceae, TM-7, and other uncultured bacteria. These bacteria may contribute to nutrient removal in SWIS. +4 NH –N