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Environ Geochem Health. 2017 Dec;39(6):1397-1407. doi: 10.1007/s10653-017-9931-8. Epub 2017 Mar 13.

Biochar-based constructed wetlands to treat reverse osmosis rejected concentrates in chronic kidney disease endemic areas in Sri Lanka.

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Department of Civil Engineering, The Open University of Sri Lanka, Nugegoda, Sri Lanka.
National Water Supply and Drainage Board, Ratmalana, Sri Lanka.
National Water Supply and Drainage Board, Anuradhapura, Sri Lanka.
Environmental Chemodynamics Project, National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka.
School of Civil Engineering and Surveying, Faculty of Health, Engineering and Sciences, University of Southern Queensland, West Street, Toowoomba, QLD, Australia.
International Centre for Applied Climate Science, University of Southern Queensland, West Street, Toowoomba, QLD, Australia.


The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20-85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K+, Ca+2, Mg+2, etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters.


Biochar; CKDu; Constructed wetlands; Fluoride; Phytoremediation; Reverse osmosis

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