This study investigated the effect of coagulation/flocculation treatment process on upgrading wastewater treatment plant. A comparison between two different coagulants (alum – ferric chloride) with different dosage and pH values were applied to the coagulation processes. The experiments were performed in a conventional jar-test apparatus in El Berka wastewater treatment plant in El Sallam district, Cairo, Egypt. The results reveal that pH values (7–8), enhance removal efficiency of the COD, TSS and total phosphorous (TP). Percentage removal of 25.7%, 52.6% and 16.7% of COD, TSS and TP, of the blank sample while the removal efficiency increased to be 55.2%, 84.4% and 64% of COD, TSS and TP, respectively, by the addition of 80 mg/L alum and 66.1%, 91.6% and 89.5% removal of COD, TSS and TP, respectively, were achieved with the addition of 100 mg/L ferric chloride to the wastewater samples. The optimum pH value for alum was 7 and 8 for ferric chloride.