Seasonal differences in treatment efficiency of a set of stabilization ponds in a semi-arid region

Abstract

This article aims to determine the significant differences of the seasonal changes of pH, chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS) parameters in a wastewater stabilization pond. The variation of these parameters followed the seasonal pattern of temperature. The mean seasonal pH of the influent wastewater ranged between 7.8 (in spring) and 7.9 (in summer), while in the final effluents it was between 7.9 (in winter) and 8.3 (in summer). The mean seasonal COD of the influent wastewater ranged between 650 mg L−1 in spring and 600 mg L−1 in autumn, whereas in the effluents it was between 150 mg L−1 in autumn and 270 mg L−1 in spring. The mean seasonal BOD5 of the influent wastewater ranged between 360 mg L−1 in autumn and 390 mg L−1 in winter, whereas in the effluents it was between 66 mg L−1 in summer and 130 mg L−1 in winter. The results showed that the percent removals of COD, BOD5 and TSS from final effluents were maximum in summer for COD and BOD5 (76%), summer (83%) and for TSS in winter (78%), respectively. Data analysis showed that there were significant differences between parameters of pH, COD, BOD5 and TSS at four different seasons (p < 0.001) in final effluents.