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

Abstract

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, Mg, 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.

Efficacy of Reverse Osmosis in Reducing Chronic Kidney Disease of Unknown Etiology in Sri Lanka: A Narrative Review 

“…After reviewing the final 14 of articles [14,18,20,21,[23][24][25][26][27][28][29][30][31][32] , 10 themes were recognized. These themes were confirmed after multiple discussions with experts in the field of CKDu and RO techniques in Sri Lanka, individuals in charge of maintaining RO machines and consumers of RO water.…”

“…These filters are made of locally available soil, Calicut tile, biochar, Vetiver grass, Scirpusgrossus, water lettuce and water hyacinth. As a result, total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20-85%) and most met desirable levels of stipulated ambient standards [28]. However, this method does not address the issue of environmental contamination.…”

Water Scarcity – A Concealed Phenomenon in Sri Lanka: A Mini Review

“…A Bayesian network classification model derived that the population density has a significant correlation with river water quality parameters and should be less than 2375 persons/km 2 to maintain appropriate water quality for domestic purposes in the Kelani river basin, Sri Lanka (Liyanage and Yamada, 2017) . Inorganic and organic pollutants from agriculture, domestic wastewater, cyanotoxin contamination, disposal of brine from community-based water treatment plants, stormwater, and leachate from the municipal solid waste disposal in open dump sites are the sources of surface water pollution in Sri Lanka (Athapattu et al, 2017; Jayasiri et al, 2022; Liyanage et al, 2016; Wijekoon et al, 2022). Further, saltwater intrusion due to excessive pumping of coastal groundwaters and water quality deterioration of the groundwater due to geogenic contaminants such as fluoride, high total dissolve solids, and hardness are other issues of economic water scarcity in Sri Lanka (Manage et al, 2022; Hettithanthri et al, 2021).…”

Remoção de fluoreto da água com o uso de Eichhornia crassipes: otimização do processo com adição de fitormônios

“…Ademais, estas pesquisas no geral não têm como objetivo principal a observação das remoções de fluoreto, mas sim de compostos que contém flúor em sua estrutura molecular ou o seu monitoramento como contaminante secundário ou interferente na remoção de outras espécies químicas de interesse (Athapattu et al, 2017;Li et al, 2014;Zurita et al, 2012). Em água subterrânea rica em arsênio, por exemplo, Zurita et al…”

“…Já a diferença entre vazões de entrada e saída (Apêndice A), decorrente do processo de evaporação e evapotranspiração, entretanto, para os tratamentos com TRH de 2 d. Isso motivou a alta variação nos resultados de remoção de carga de fluoreto para estes tratamentos.Em concordância com o previamente observado em relação às remoções relativas de carga de fluoreto, as remoções, agora em termos absolutos, foram maiores para os tratamentos com E. crassipes (P e PA). Fica claro, dessa forma, que as plantas são essenciais para este sistema de tratamento quando empregado para desfluoretação Athapattu et al (2017). e Zurita et al (2012) também reportaram maiores remoções de fluoreto em wetlands plantadas do que não plantadas.…”