Comparison of Septage Treatability Using Basil Seed Plant Coagulant and Chemical Coagulants

In this study, septage wastewater treatment using the flocculation/coagulation process by the natural coagulant Ocimum basilicum L. (basil) and chemical coagulants polyaluminum chloride (PAC), ferric chloride, and alum was studied. Under different conditions, the extraction of the seed of O. basilicum was done by maceration method, and SPSS 23 software was used to identify the most effective extract and chemical coagulant. The effects of five parameters-pH, coagulant dose, coagulant aid dose, rapid mixing time, and slow mixing time-on the reduction of COD, TSS, NH₄, and TP in septage samples were examined by conducting the Central Composite Design (CCD). Optimum conditions predicted by the response surface models were determined at pH 4.00, coagulant dose 498.50 mg/L, rapid mixing time 5.00 min, slow mixing time 21.60 min for natural coagulant, and pH 4.01, coagulant dose 372.88 mg/L, and coagulant aid dose 1.55 mg/L for chemical coagulant (PAC). Under optimal conditions, the reduction percentages of COD, TSS, NH₄, and TP parameters were 64.40, 87.30, 70.56, and 71.92 for natural coagulant, and 65.30, 73.42, 71.12, and 74.68 for chemical coagulant (PAC).