Soil contamination by direct disposal of reverse osmosis reject water onto the ground in the Chronic Kidney Disease of unknown etiology (CKDu) prevalent areas

Abstract

Reverse Osmosis (RO) units have been installed in areas where Chronic Kidney Disease of unknown etiology (CKDu) prevails to provide good quality drinking water. At present, RO reject water is directly discharged onto the ground, which may cause potential soil contamination. This research investigated the possibility of soil contamination and their levels due to direct disposal of RO reject water onto the ground. Water samples (RO permeate and reject) and soil samples from disposal sites and reference sites were collected and analyzed for various constituents (Ca2+, Mg2+, Na+, K+, F-). RO reject water showed high concentrations of Ca2+, Mg2+, Na+, K+ and F- ions. Analysis of soil samples from RO reject water disposal sites showed high concentrations of Ca2+, Mg2+, Na+ and K+ compared to the reference sites and optimum levels for healthy growth of plants. This was mainly attributed to the direct discharge of RO reject water rich in such constituents onto the ground. In conclusion, soil contamination was observed due to direct discharge of RO reject water onto the ground, which may lead to reduction of soil fertility and retarded plants growth in the long run.