EVALUATION OF NANOFILTRATION PROCESS FOR FLUORIDE REMOVAL FROM GROUNDWATER IN THE CHIANG MAI BASIN

Abstract

The highly concentrated fluoride in groundwater has been observed in confined aquifers of the alluvial sediments in the Chiang Mai Basin. Nanofiltration process has been applied to the control of fluoride exposure to the local residents, which caused the serious dental and osteal fluorosis.
A polyamide nanofiltration is widely used for the membrane plants, which was found to be limited fluoride removal by a function of feeding pH. In contrast to neutrality to weak basic condition that gave high fluoride removal, it tended to form calcium carbonate scale on the membrane surface. This study showed optimum combination of pretreatment and permeate recovery in the membrane operation.