Decade long study reveals that wastewater treatment upgrades trigger significant shifts in river microbial and viral functions

A 10-year study by the Chinese Academy of Sciences shows wastewater upgrades lead to a 70% shift in nitrogen cycling and viral reprogramming in rivers.

By: AXL Media

Published: Mar 3, 2026, 4:57 AM EST

Source: The information in this article was sourced from KeAi Communications

Longitudinal analysis of Beijing river systems

A research team led by Yaohui Bai from the Research Center for Eco-Environmental Sciences has concluded a ten year study on the ecological impact of wastewater treatment plant (WWTP) upgrades. The research, conducted between 2015 and 2024, focused on Beijing’s Tonghui and Qing Rivers. By comparing a river that underwent an upgrade during the study period with one upgraded previously, the team sought to provide field-based evidence of how improved effluent quality alters the microscopic life within receiving aquatic environments.

Substantial improvements in water chemistry

The primary objective of the WWTP upgrades was the reduction of nutrient pollution, and the data confirms significant success in this area. In the Tonghui River, total nitrogen concentrations dropped from levels of 20 to 30 mg per litre to approximately 10 mg per litre following the 2017 upgrade. Researchers attributed this marked decline to newly incorporated treatment processes specifically designed to remove organic nitrogen. While these chemical improvements were expected, the subsequent biological responses revealed a more complex ecological restructuring.

Microbial community and nitrogen cycling shifts

The study uncovered a dramatic reconfiguration of the river’s nitrogen-cycling bacteria. While the overall species richness remained stable, the ratio of nitrifiers to denitrifiers decreased by 70 percent after the upgrade. This shift indicates that the microbial community moved toward enhanced denitrification, a process that converts nitrates into nitrogen gas. Analysis of community variation showed that these changes were driven by the gain or loss of specific taxa within a stable core microbiome rather than a complete replacement of species.