Removal of Harmful Constituents from Geothermal Water by Selected Anion Clays

Four kinds of anion clays (hydrocalumite, hydrotalcite, iowaite and takovite) synthesized in this study were used for removing harmful constituents from the geothermal waters collected from three hydrothermal areas located in Qinghai Province, northwestern China. Iowaite performed better than the other anion clays in term of water dearsenication, while hydrotalcite exhibited higher efficiencies on removal of fluoride and sulphate. The increase in dosage of iowaite dramatically elevated the chloride concentrations of the treated geothermal waters as the enhanced release of original interlayer chloride in the iowaite duo to the anion exchange. Therefore, hydrotalcite is the optimal sorbent for uptake of undesirable constituents in Qinghai geothermal waters and is promising for wider use in treatment of geothermal waters in the future.