Harvesting surface rainwater – purification using Moringa oleifera seed extracts and aluminum sulfate

Abstract

Ground water harvesting is a method of collecting surface runoff from a catchment’s area and storing it in surface reservoirs. The water harvested is usually contaminated and turbid. Methods used to purify water include filtration, sedimentation, boiling and chlorination. This project was carried out in Nyatike district, Western Kenya where water is scarce and water-borne diseases such as cholera, typhoid and dysentery are prevalent. The main objectives of the research were to disseminate water harvesting technology using hand-dug water pans and to evaluate the effect of Moringa oleifera seed extract as water purifier. Sites were identified for construction of demonstration water pans. Moringa seeds were milled after which methanol was used to extract water soluble components.. Representative water samples from Victoria Lake, Kuja River and Otho pond were collected and subjected to purification studies using M. oleifera seed extract and aluminum sulfate. M. oleifera was also tested for antibacterial activity against Escherichia coli (ATCC 25922) Salmonella typhii and Vibrio cholerae (ref. Romel Cary Blair Lot. 452610). A total of 452 farmers were trained in water harvesting and purification technologies. Studies on water purification indicated that Alum lowered the water pH from 7.4 to 4.4 while samples treated with Moringa extract did not affect water pH. Alum was the better water purifier whereby application of 0.25 g/L decreased water turbidity from 310.7 to 1.1 NTU while M. oleifera decreased turbidity to 45.6 NTU. M. oleifera extract showed antibacterial activity. S. typhii was the most sensitive while V. cholera was the least sensitive.