Assessing of channel roughness and temperature variations on wastewater quality parameters using numerical modeling

Nowadays, problems and barriers to supply adequate water and address environmental issues have caused wastewater treatment (WWT) to be considered a high priority. In light of high costs of WWT, using natural capacities to reduce pollution could be potentially economically significant. In this paper, the impact of varying temperature and channel roughness has been investigated on the wastewater quality parameters using the QUAL2K (Q2K) Numerical Model. The results show, as temperature increases, the reduction rate of Biochemical Oxygen Demand (BOD) is more than the Chemical Oxygen Demand (COD). Also, organic nitrogen (ON), organic phosphorus (P), coliforms, total organic carbon (C), total suspended solids (TSS) and total nitrogen (TN) decrease; but nitrate concentration (NO₃) increases. This numerical assessment indicates that the purification rate is greater as temperature rises above 30°C. The results show that by increasing channel roughness, BOD, COD, Particle Organic Matter (POM), organic nitrogen, phosphorus and coliforms have descending trends while inorganic phosphorus and ammonium concentrations have ascending trends. According to the obtained results, nitrate (NO₃) has a decreasing trend when the Manning Roughness Coefficient (N) is higher than 0.04 along the channel, but is reduced when “N” is less than 0.04.