A comparison of stream biological responses to discharge from wastewater treatment plants in high and low population density areas

Abstract

The ultimate purpose of this study was to identify broad relationships that may have relevance for the risk assessment of chemicals and materials that are discharged to receiving streams via municipal wastewater treatment plant (WWTP) effluents (e.g., consumer product ingredients). The effects of municipal wastewaters occurring in high population density (>500 persons per square mile, urban) and low population density (<500 persons per square mile, rural) environments were determined via analysis of biological, habitat, and water chemistry data collected both immediately upstream and downstream of 221 WWTPs in Ohio, USA. Several biological and chemistry indicators demonstrated poorer water quality in urban areas compared to rural areas. After considering the effect of river size, adverse effects downstream of WWTPs for both fish and macroinvertebrate communities were clearly identified for only urban areas. These data indicate that WWTP potency may be greater in urban areas compared to rural areas.