Application of cactus powder to minimize the use of aluminium sulphate as a coagulant during water treatment at Movit products Limited

Abstract

In this research, the turbidity removal/coagulation activity of three coagulants; alum, cactus powder and a combined coagulant (cactus powder + alum), and their effect on other parameters of pH, Electrical Conductivity, and color of raw and clarified water samples were investigated. The parameters of turbidity, pH, Electrical Conductivity, and color of clarified water were determined using the jars test method. Three water samples were collected on three different days from the effluents from the activated sludge process at Movit Products Limited. Four different concentrations of each coagulant, 1%, 2%, 3% and 3.5% were prepared and each was used with the jars test experiment to determine the turbidity removal, pH, electrical conductivity and color of clarified water. The results for each water sample were determined and tabulated as shown in the appendix on pages 18-20. The respective averages of the results were taken. Alum average turbidity removal was found to be 27.69% at 1%, 62.11% at 2%, 87.13% at 3% and 93.21% at 3.5%; Cactus powder average turbidity removal was found to be 19.28% at 1%, 54.5% at 2%, 80.97% at 3% and 89.16% at 3.5%; and interestingly, a combination of cactus powder and alum gave the highest average turbidity removal of 29.76% at 1%, 65.15% at 2%, 89.43% at 3% and 94.28% at 3.5% (percent turbidity removal at percent coagulant concentration). Alum coagulant significantly lowered the pH of water from 7.67 at 0% to 4.8 at 3.5% concentration, however cactus and a combination of cactus and alum marginally affected the pH of water, and their average pH was respectively found to decrease from 7.67 to 7.48 and 7.67 to 7.4 when the coagulant concentration was increased from 0% to 3.5%. Average electrical conductivity increased from 118.00µs/cm to 178.00, 136.67 and 139.67µs/cm for alum, cactus and a combination of alum and cactus respectively. Alum showed a significant increase in the electrical conductivity of water while cactus and a combination of cactus and alum showed marginal effect of water conductivity. The average color of water decreased from 125.67PtCo to 14.00PtCo, 17.00PtCo and 13.00PtCo for alum, cactus, and a combination of both respectively when coagulant concentration was increased from 0% to 3.5%. A combination of both alum and cactus powder coagulants gave the highest color removal. Therefore, a combination of alum and cactus powder is a very good coagulant and is recommended for use in water treatment than using alum alone. This would even further reduce the amount of alum required for coagulation hence a reduction in cost of purchasing alum, residual alum in water would be reduced and hence its harm on human beings, and less alum would be introduced to the environment.