Enhanced Removal Of Antimony In Drinking Water Resource Through Conventional Water Treatment Processes

Study on processing antimony polluted surface water has not reported in China, few reported abroad were tested on bench scale. In this thesis, removal of antimony in drinking water resource through an enhanced conventional water treatment process was studied. To enhance the process, coagulants and their applying conditions were tested first. The results indicated that ferrous coagulant was more effective than alumina coagulant, and polymerric sulfate iron (PFS) is the most efficient one for antimony removal. Further investigations found that at low pH conditions (pH=4⁶) PFS removal efficiency increased dramatically compared to that at neutral pH conditions. According to analysis of SEM, X-ray spectroscopy and i potential, the floc precipitates forming from the coagulant hydrolysis at low pH have larger positive charge, bigger specific surface, looser structure and greater antimony/iron ratio compared to moderate pH conditions. The most removal of antimony during coagulation process was achieved at the first several minutes of rapid mixing period. It might conclude that coprecipitation and adsorption between coagulant hydrosis products and antimony account for main antimony removal mechanism during coagulation.Pilot scale experiment simulating local water plant treatment process of coagulation, sedimentation and filtration showed: when raw water pH was adjusted to 5⁶, and PFS was dosed at 150mg/L, effluent of the filter with granular quartz bed met the National Environmental quality standards for surface water (GB3838-2002); There was little difference in effluent concentration of antimony between the fine quartz filter (d₁₀=0.5, K₈₀=1.5) and the common quartz filter (d₁₀=0.8, K₈₀=1.5). Also, there was little difference between fresh filter bed and the used tilter bed which has been operated for 6 months, with the same size diffusion new. Activated alumina was evaluated for antimony removal, and showed great adsorption capacity, suggesting that it may be used as advanced process after sand filtration.Since the study demonstrated the removal of antimony in drinking water resource through enhanced conventional water treatment process was satisfactory, the achievements of the study has been applied to redesign and reconstruct a local water treatment plant whose resource was contaminated with antimony.