Wastewater seasonal characterization and evaluation of reclamation potential of biological nutrient removal processes: a case study in Türkiye

This paper investigates the performance of biological nutrient removal (BNR) processes for wastewater reclamation potential. A case study of three conventionally designed BNR plants in Kocaeli, Türkiye evaluated the seasonal profile of their nutrient removal efficacy and potential reduction of their effective discharge into the receiving water bodies. The key parameters studied included - chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solids (SS), total nitrogen (TN), total phosphorus (TP), and heavy metals. The analysis showed that effluent COD, BOD, SS, TN and TP concentrations of all three BNR plants were below 90, 20, 21, 9.2 and 1.2 mgL^{− 1} respectively, in compliance with the discharge limits set by the Turkish Water Pollution Control Regulations and the United Nations Food and Agricultural Organization for all the seasons. Further statistical analyses of the samples indicated that the data from all three BNRs followed a normal distribution, with p values generally greater than 0.05. Within the scope of analysis, no statistically significant differences were detected among the three BNRs. Beyond the current use of wastewater from the three plants for agricultural usage, further integration of dedicated wastewater recovery units is recommended alongside conventional BNR processes for enhanced wastewater reclamation for industrial and municipal applications.