Purification of Charco dam water by coagulation using purified proteins from Parkinsonia aculeata seed

Large rural populations in arid areas of Tanzania use polluted water from man-made water reservoirs (charco dams) for drinking with minimal or without treatment. The ability of coagulant proteins purified from Parkinsonia aculeata seed to purify water from charco dam was studied. The P. aculeata coagulant proteins were purified from P. aculeata crude seed extract by simplified ion exchange chromatography (IEX). The Purified proteins are cationic in nature with molecular mass of about 6 kDa, very similar to that of Moringa oleifera proteins. Jar tests were used to investigate the coagulation performance of the purified proteins in comparison to that of a conventional chemical coagulant, which is aluminium sulphate (alum). Coagulation efficiencies of the purified proteins and alum varied slightly. The optimum coagulation dosages for the purified proteins and alum were 6 mg/L and 14 mg/L, which reduced turbidity from 880 NTU (initial raw water turbidity) to 3 and 13 NTU, respectively. The purified proteins reduced turbidity along with Fe²⁺, NO^3- and PO₄^3- in coagulated water samples to levels that complied with Tanzania Drinking Water Quality Standards, and, in some cases with WHO standards. Contrary to alum, PAP did not affect the pH and alkalinity of treated water hence; coagulant proteins do not need additives to regulate the pH. The IEX method used for seed protein purification is simple and easily scalable, and hence, it is recommended for production of potable water for poor communities.