Refinement of reverse osmosis concentrate through Bio-Char embedded Bio-Geo filter

Abstract

Installation of Reverse Osmosis (RO) plants in community organizations to supply portable drinking water is an attempt in the areas with Chronic Kidney Disease of unknown etiology (CKDu) in the North Central Province in Sri Lanka. However, there have been no concerns on the brine from the RO plant, which has been directly discharged to the nearby irrigation canal or to the ground. This research was focused to investigate remedial measures for brine of ROthrough phytoremediation process using a pilot-scale surface and subsurface water construction wetlands. The field experiments were carried out focusing the community based RO water supply unit located at Medawachchiya, Sagilikanadarawa.Both surface and subsurface water Constructed Wetlands (CW) was established to measure the removal efficiency of RO concentrates through wetlands. Native soil, Calicut tile and biochar were used in proportions of 80, 17.5 and 2.5% by weight respectively as filter materials in the subsurface CWs.Vertiver Grass and Scirpus Grossus wereselected for the sub surface wetland while Water Lettuce and Water Hyacinth were as free water surface CW. The field experiment was carried out120 days for free water surface and subsurface wetlands respectively and water quality parameters were tested periodically for CKDu sensitive parameters. The results showed that the CKDu sensitive parameters such as Total Dissolved Solids, Hardness, Total Alkalinity and Fluoride were reduced up to 30, 45, 65 and 80% respectively and biochar used in the subsurface media represent major role in removing fluoride from the system. Therefore the invented bio-geo constructed wetland system is an economical and effective option for reducing high concentrations of RO reject water before discharging into the inland waters.