Study of the Efficiency of Arsenic Removal from Drinking Water by Granular Ferric Hydroxide (GFH)

Pollution of surface and ground water to arsenic (As) has been reported from many parts of the world and in some regions of Iran especially in Kurdistan province. Natural pollution of water to As is in fact dependent to geological characteristics of a region. To day various methods have been recommended for As removal that each of which has special advantages and drawbacks. Granular ferric hydroxide (GFH) is a relatively new adsorbent available in market which is principally introduced for As removal. Methods This study was an applied survey in which the effects of changing contact time As concentration adsorbent weight pH as well as the effect of sulfate and chloride ions in arsenic removal were determined. Moreover the model of absorption by GFH was studied and compared with Freundlich and Langmuir models. Raw data were analyzed by Excel and SPSS softwares. Results Results showed that As adsorption by GFH imitate both the Freundlich and Langmuir equations (with R2 >0.95). Optimum PH was 7.5 and duration of the process about 30 minutes was sufficient for optimum removal of As. It was also found that efficiency of As removal was high when small amounts of adsorbent were used. Furthermore sulfate and chloride ions in concentrations used in this study had no noticeable effect on As removal and Fe added during process remains in the water more than the standard value (0.3 mg/l). Conclusion According to this study GFH could be considered as a suitable adsorbent for As removal from polluted water resources because of its high performance without any needs to PH adjustment. However there are few drawbacks such as Fe addition and relatively high initial cost.