Removal of Turbidity and Microbial Load for Household Water Treatment

Abstract

Background: The use of inorganic chemicals for the removal of turbidity and bacteria was recognized as one of the public health and environment concern due to disinfection byproduct formation and sludge production. In addition, unsafe drinking water is a paramount concern because of the fact that, 75% of all diseases in developing countries are arising from polluted drinking water especially in rural parts of developing countries. We conducted a series of experiments on the effectiveness of in removing turbidity and microbes by using both synthetic and natural surface water samples in the laboratory of Environmental Health Sciences and Technology, Jimma University from February to April, 2013. A conventional jar test apparatus was used to achieve uniform agitation rate throughout the experiment. The experiments were designed targeting both dose and contact time of plant coagulants and synthetic chemicals while recording major influencing water quality parameters. Spread plating method was employed for microbial test using plant species. Plant coagulants showed relatively lower removal efficiency (≈70%) as compared to alum (≈80%) at low turbidity (20 NTU) in synthetic water. However, in natural water samples of low turbidity, plant coagulants showed high rate of turbidity removal efficiency (≈90%) like that of alum. Plant coagulants can also achieve maximum turbidity removal (≈97%) like that of alum in medium turbidity level (200 NTU) in both natural and synthetic water samples. The experimental result revealed that plant coagulants were able to meet World Health Organization standards of drinking water quality (< 5 NTU) in terms of turbidity. The microbial reduction experiment also revealed that plant coagulants can effectively disinfect water at low turbidity but becomes less potent disinfectant as turbidity increases.