Occurrence and removal of conventional pollutants, estrogenicities, and fecal coliform in village sewage treatment plants along the Yangtze River, China

The present study investigated the occurrence and removal efficiency of some conventional pollutants, estrogenic effects, and fecal coliform in influents and/or effluents of village sewage treatment plants (STPs) in the upper, middle, and lower reaches of the Yangtze River Basin. The water quality of sewage from the village STPs showed significant seasonal and spatial variability. The removal rates of conventional pollutants by the village STPs were mostly lower than urban STPs, thereby resulting in that the water quality compliance rate of the effluents was only 33.3%. In addition, the average removal rate of estrogenic compounds was only 22.2%, which caused the estrogenicity of effluent to exceed the safety threshold. And E2 was determined to be the main estrogenic component. Moreover, ultraviolet (UV) disinfection, as the main disinfection treatment process of sewage along the Yangtze River Basin, was unable to meet the discharge standard of fecal coliform. The sequential chlorine (10 mg L-1)-UV (20 mJ cm(-2)) disinfection was found to both achieve up-to-standard discharge of fecal coliform and increase the removal rate of estrogenic effect from 3.78 to 9.86%. Overall, the present study provides valuable information on the conventional pollutants, estrogenic effects, and fecal coliform in sewage from village STPs along the Yangtze River Basin, and practical suggestions for basin-wide pollution control.

Automated summary

This study investigated the occurrence and removal efficiency of pollutants, estrogenic effects, and fecal coliform in sewage from village sewage treatment plants (STPs) in the Yangtze River Basin. The study found significant seasonal and spatial variability in the water quality of sewage from village STPs. The removal rates of pollutants and estrogenic compounds were low, and ultraviolet disinfection was unable to meet the discharge standard for fecal coliform. Sequential chlorine-UV disinfection was found to be effective in improving the removal rate of estrogenic effects and achieving up-to-standard discharge of fecal coliform.