Study on natural soil coagulants for point-of-use drinking water treatment

Abstract

Natural soil coagulants were used for domestic drinking water treatment in Ethiopia because of lacking drinking water supply. In this study, two soils were collected from Ethiopia and jar test was used to investigate the optimum working conditions, performance and safety of them. The turbidity removal efficiencies of soil A and soil B are 74.5% and 91.1% (initial turbidity=400 NTU), respectively. The pH of purified water can meet drinking water standards of Ethiopia (pH=6.5-8.5). Both soils contribute to remove TOC when the initial concentration of it is high. A small amount (0.5 mg. L-1 or 1 mg. L-1) of poly-aluminum chloride can improve the performance of soil coagulants for the removal of turbidity. The application of soil coagulants didn't introduce coliforms, although the total bacteria number of treated water increased to 40 CFU (soil A) and 81 CFU (soil B), still meeting the drinking water quality standards (<=100 CFU).