Insights into heterotrophic denitrification diversity in wastewater treatment systems: Progress and future prospects based on different carbon sources

Nitrate, as the most stable form of nitrogen pollution, widely exists in aquatic environment, which has great potential threat to ecological environment and human health. Heterotrophic denitrification, as the most economical and effective method to treat nitrate wastewater, has been widely and deeply studied. From the perspective of heterotrophic denitrification, this review discusses nitrate removal in the aquatic environment, and the behaviors of different carbon source types were classified and summarized to explain the cyclical evolution of carbon and nitrogen in global biochemical processes. In addition, the denitrification process, electron transfer as well as denitrifying and hydrolyzing microorganisms among different carbon sources were analyzed and compared, and the commonness and characteristics of the denitrification process with various carbon sources were revealed. This study provides theoretical support and technical guidance for further improvement of denitrification technologies.