Sulfate reduction and denitrifying sulfide removal as a natural remediation process in an inland river

The simultaneous removal of sulfate, nitrate and organic carbon by biological processes in engineered systems is a relatively new area of research. This study is the first to demonstrate that these biological processes occur in natural systems resulting in the remediation of polluted river water. Samples of water and sediment were collected from a 5 km-long section of Liming River, Daqing, China, in August and September, 2012. Sections with reduced sulfate concentration, autotrophic denitrification and heterotrophy, together with their dominant strains, were identified. Over a river section that was 3 km long, sulfate reduction (SR) and denitrifying sulfide removal (DSR) processes together removed approximately 2100 tons of sulfate, 2300 tons of nitrate, and 3200 tons of chemical oxygen demand (COD) from the river water annually. Microbial community was shifted to adapt to transformation of pollutants and point-source pollution in the studied river.