Relationships of Dissolved Oxygen and Biochemical Oxygen Demand in Sewage Effluent Releases

摘要

Bio-physicochemical measurements were made on treated sewage effluent releases at established locations within the channel of an ephemeral stream, the Santa Cruz River of Southern Arizona. Water quality samples were taken in chronological sequence, so that incremental flows at low and high hydrograph stages could be traced as the effluent moved downstream. Results indicate that DO concentrations at low effluent flows were higher than DO concentrations at high effluent flows, while, conversely, BOD concentrations at low effluent flows were generally lower than BOD concentrations at high effluent flows. Biochemical oxygen demand concentrations are affected by waste loadings, flow conditions, phytoplankton growth and nitrification. Mean river deoxygenation rates (kr) in sewage flows after six river miles from the Tucson Sewage Treatment Plant were always negative or increasing, which is probably due to nitrification, algal growth, and concentration of organic constituents through seepage losses.