Removal of Fluoride and Hardness in Dietary Intake (water) in Chronic Kidney Disease of unknown Etiology (CKDu) Prevalent Areas by Domestic Reverse Osmosis Units

The origin of Chronic Kidney Disease of unknown etiology (CKDu) that is rapidly invadingthe dry zone of Sri Lanka has not yet been identified. However, occurrence of the disease isthought to be linked with excess levels of fluoride and hardness in drinking water. Hence, thestudy herein focuses to evaluate the suitability of domestic Reverse Osmosis (RO) units;which introduced in CKDu affected areas to remove excess fluoride and hardness.Accordingly, the drinking water quality in CKDu prevalent areas in terms of fluoride andhardness was simulated in the laboratory and the removal of aforesaid constituents usingdomestic ROs was investigated.According to water quality analyses, domestic RO units effectively removed hardness even atextremely high initial concentrations, such as 1,730 mg/L (as CaCO3). Excessive removal ofCalcium and Magnesium by the RO units was observed, thus remineralization of thepermeate up to 80-100 mg/L as CaCO3 is required to ensure health benefits. Meanwhile,fluoride removal was observed to be highly dependent upon initial fluoride and hardnessconcentrations. It was not possible to suggest an „optimum removal level‟ for fluoride, wherepermeate fluoride concentration exceeded the maximum permissible WHO Drinking WaterGuideline value of 1.5 mg/L. However, it may arise at a point where fluoride and hardnessconcentrations in raw water fall within 1.7-3.5 mg/L and 570-1,130 mg/L as CaCO3,respectively.Plausible reasons for ineffective removal of fluoride could be the relatively small size andlow ionic charge of fluoride. Additionally, high concentration of heavy ions may interferewith fluoride adsorption of activated carbon filter in the domestic RO unit. Effective fluorideremoval could be achieved by adopting appropriate pre-treatment methods for hardnessremoval. Separate threshold levels for fluoride and hardness levels in drinking water shouldbe defined, especially for CKDu patients.Keywords: Chronic Kidney Disease, Domestic reverse osmosis units, Fluoride, Hardnes

Removal of Fluoride and Hardness in Dietary Intake (water) in Chronic Kidney Disease of unknown Etiology (CKDu) Prevalent Areas by Domestic Reverse Osmosis Units

The origin of Chronic Kidney Disease of unknown etiology (CKDu) that is rapidly invadingthe dry zone of Sri Lanka has not yet been identified. However, occurrence of the disease isthought to be linked with excess levels of fluoride and hardness in drinking water. Hence, thestudy herein focuses to evaluate the suitability of domestic Reverse Osmosis (RO) units;which introduced in CKDu affected areas to remove excess fluoride and hardness.Accordingly, the drinking water quality in CKDu prevalent areas in terms of fluoride andhardness was simulated in the laboratory and the removal of aforesaid constituents usingdomestic ROs was investigated.According to water quality analyses, domestic RO units effectively removed hardness even atextremely high initial concentrations, such as 1,730 mg/L (as CaCO3). Excessive removal ofCalcium and Magnesium by the RO units was observed, thus remineralization of thepermeate up to 80-100 mg/L as CaCO3 is required to ensure health benefits. Meanwhile,fluoride removal was observed to be highly dependent upon initial fluoride and hardnessconcentrations. It was not possible to suggest an „optimum removal level‟ for fluoride, wherepermeate fluoride concentration exceeded the maximum permissible WHO Drinking WaterGuideline value of 1.5 mg/L. However, it may arise at a point where fluoride and hardnessconcentrations in raw water fall within 1.7-3.5 mg/L and 570-1,130 mg/L as CaCO3,respectively.Plausible reasons for ineffective removal of fluoride could be the relatively small size andlow ionic charge of fluoride. Additionally, high concentration of heavy ions may interferewith fluoride adsorption of activated carbon filter in the domestic RO unit. Effective fluorideremoval could be achieved by adopting appropriate pre-treatment methods for hardnessremoval. Separate threshold levels for fluoride and hardness levels in drinking water shouldbe defined, especially for CKDu patients.Keywords: Chronic Kidney Disease, Domestic reverse osmosis units, Fluoride, Hardnes