INFLUENCE OF REVERSE OSMOSIS REJECT WATER ON SOIL QUALITY IN DISPOSAL SITES OF VAVUNIYA, SRILANKA

Abstract

Reverse Osmosis (RO) technology is a major solution for facilitating the safe portable water. The aim of this study was to investigate the influence of RO reject water on soil chemical parameters (pH, electrical conductivity (EC), fluoride, and hardness) at selected RO plant locations in the Vavuniya District of Sri Lanka. Feed water, reject water, and soil samples at different depths (D1 16.5 cm, D2 33 cm, and D3 50 cm) were collected during a period of four months. The results clearly demonstrated the deterioration of soil chemical properties over time owing to ion accumulation. The observed values of pH, EC, fluoride, and hardness of the feed water ranged from 6.67 to 7.53, 798.6-1437 S/cm, 0.37-1.43 mg/L, and 374.10-586.2 mg/L, respectively, whereas the reject water varied from 6.92 to 7.86, 1402.6 -5877 S/cm, 1.32 -2.64 mg/L, and 735 - 2808 mg/L. As a result, releasing RO reject water directly into the soil without primary treatment may have an unfavourable impact on land quality and soil health. Hence, stringent policies and regulations should be implemented to reduce the negative consequences on disposal sites.