Coagulation-flocculation technique for domestic wastewater treatment in the city of Ain Aouda, Rabat, Morocco

Abstract

The goal of this study was to investigate the performance of coagulation-flocculation, and sedimentation tests to reduce contaminant concentrations in domestic wastewater to ecologically acceptable levels. The tests were performed at the (ONEE) laboratory using a jar test apparatus (GPB FLCDidatec, France) for enhancing the primary treatment of domestic wastewater effluent from the wastewater plant of Ain Aouda City, Rabat, Morocco. Aluminum sulphate Al2(SO4)3.18H2O (termed alum) was employed as a coagulant in the study. The impact of coagulant doses and pH at optimum dosage on the process of coagulation was studied and conditions were optimized to obtain the best removal of studied pollutants. The evolution of physico-chemical parameters pre-and post-treatment was monitored to determine the efficacy of the process. The turbidity and total suspended solids (TSS) were the best indicators of the treatment’s efficacy of coagulant concentration (150mg/L) within the pH optimum of 7. Laboratory tests have shown 98.4% of turbidity, and 97% total suspended solids removal at initial concentrations of 121 NTU, 220 mg/L respectively. Also, it has shown good removal efficiency for COD, BOD5 of the order 83%, 77% at initial concentrations of 340 mg/L, 150 mg/L respectively. Following the coagulation tests, the examination of the main parameters studied revealed that the degree of contamination had decreased. This is confirmed that Aluminium sulphate as a coagulant has proven its effectiveness in the treatment of domestic wastewater in this study.