Efficiency of <i>Carica papaya</i> Seeds in the Coagulation of Moderately Turbid Wastewater

Abstract

The continuous degradation of available water resources coupled with the high cost of conventional water treatment has led to alternative, sustainable and cost-effective methods of treating wastewater. This study investigated the efficiency of Carica papaya seeds in the coagulation of moderately turbid water while determining the optimum treatment dosage and evaluating the treatment efficiencies compared to the use of conventional Aluminum sulphate (alum). Moderately turbid wastewater was obtained from Ala River tributary in Akure, Ondo State, Nigeria. The coagulation experiments were carried out at room temperature in a jar test. The experiments were carried out using 0.2 g/L, 0.4 g/L, 0.6 g/L. 0.8 g/L, 1.0 g/L, 1.2 g/L and 1.4 g/L doses of Carica papaya seed powder. An alum dose of 1 g/L was used as a control dose. The pH, turbidity, total hardness, total dissolved solids (TDS), and biochemical oxygen demand (BOD) of the raw water and treated water samples were analyzed. The pH of the raw water sample was 7.8; after treatment, the pH ranged from 7.7 at 0.2 g/L to 8.0 at 1.0 g/L treatment dose with Carica papaya seed powder. The optimum dose for turbidity removal was found to be 0.8 mg/L which amounted to 74.5% turbidity removal efficiency compared to 93.1% for alum. The hardness of the raw wastewater sample was 102 mg/L. After treatment, the hardness reduced from 99.4 mg/L at 0.2 g/L treatment to 77.6 mg/L at an optimum dose of 0.8 g/L. The TDS reduced from 564 mg/L at 0.2 g/L treatment with Carica papaya seed powder to 388 mg/L at an optimum dose of 0.8 mg/L amounting to a 78.9 % contaminant removal. The percentage BOD removal at 0.8 g/L of Carica papaya treatment was 86.3% while at 1.0 g/l, it was 100%. This study demonstrated that Carica papaya seeds is useful for the removal of contaminants from moderately turbid wastewater at varying percentages under different doses of papaya seeds.