Would open disposal of concentrate from low pressure membrane based plants treating fresh or slightly saline groundwater make negative environmental impacts?

Abstract

Low Pressure Reverse Osmosis (LPRO) plants have been installed in the North Central province of Sri Lanka, as a measure to supply good quality water to people who are affected with Chronic Kidney Disease of unknown aetiology (CKDu). The concentrate of these membrane based samples have been released to the soil without any treatment. In this study, the quality of discharging concentrate and effects of the discharge on soil were investigated. Statistical analysis techniques were employed in determining the effects. Among the analysed pH, EC, Na+, hardness, TOC, F− and NO3− -N of feed and concentrate streams, EC and hardness showed statistically significant changes. In soil analysis, in plants at which the concentrate have been discharged for a longer durations, significant changes were found in pH and K content of soil. The affected soils shows higher pH and lower K levels compared to unaffected soils, indicating exchange of H+ and K+ ions present in soil with Ca2+ and Mg2+ present in concentrate. This finding suggests that monitoring of receiving soils at LPRO plants in future is required.