Arsenic removal from drinking water

Arsenate removal from drinking water was investigated using precipitation coprecipitation, lime softening, and adsorption methods. For precipitation coprecipitation method, Box-Behnken experimental design method was used to investigate the influence of major operating variables such as initial arsenic concentration, pH, and coagulant dose on arsenate removal efficiency and to find the combination of variables resulting in maximum arsenate removal efficiency. Ferric chloride, ferric sulfate, ferrous sulfate, and aluminum sulfate were used as a coagulant. Ferric chloride was found as effective and reliable coagulant considering required concentration and residual arsenate and iron concentration after sedimentation and filtration in the effluent. Although all types of polymers increased the removal efficiency of the treatment method, application of cationic polyelectrolyte was more effective than anionic and nonionic ones. Box?Behnken statistical experiment design and response surface methodology offer an efficient and feasible approach for arsenate removal and it could be employed to determine the optimum conditions for arsenate removal while minimising the number of experiments required.Lime softening for arsenate removal was required larger amount of coagulant doses and higher operating pH than iron and aluminium salts and consequently a large volume of sludge is produced and strong acids would probably be needed to adjust the pH after treatment.Clinoptilolite was used for arsenate removal from drinking water by adsorption. The iron modified zeolites were found as effective adsorbent for the arsenate removal from aqueous solution. According to the isotherm studies, GCFeA has larger capacities of adsorption and adsorption bond between the As(V) ion and adsorbent is the strongest. The pseudo second-order kinetic model provided a good correlation for the adsorption of arsenate by GCFeA and GCFeB in contrast to the pseudo first-order model. The GCFeA could treat approximately 3600 bed volumes of arsenate before column exhaustion.Removal of arsenic from real groundwater in Sasalı-İzmir was investigated using obtained optimum conditions from coagulation and flocculation, lime softening, and adsorption method in order to compare arsenic treatment results of synthetic and natural arsenic contaminated water. The obtained results from natural arsenic contaminated water are consistent with the previous studies on arsenate removal from synthetic contaminated tap water.