Influence of Rural Sewage Effluent on Riverine Water Quality and Microflora

Abstract

In this study, the impact of rural sewage effluent on the water quality of an agricultural water channel and rural river was investigated. Treated water samples from rural sewage, an agricultural water channel, and a rural river were analyzed. In addition, microflora analyses were conducted on the sediments and water samples from each location using the quinone profile methodology. The results revealed the critical need to study the impacts of treated sewage effluents on freshwater ecosystems. The nitrogen and phosphorus concentrations of water in the agricultural water channel increased downstream of the treated wastewater (TW) inflow. The annual average nitrogen and phosphorus concentrations in the TW were 7.33 mg L^-1 and 1.83 mg L^-1 higher, respectively, than those measured in the agricultural water channel upstream of the reclaimed wastewater inflow. Furthermore, a slight increase in the sediment microbial biomass, determined by the loss-on-ignition method, was observed in the treated water flowing into the agricultural water channel. It was clarified that rural sewage effluents with a high concentration of nutrients affect the microflora in the agricultural water channel, and, in particular, contribute to the increase in the amount of denitrifying bacteria.