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This paper investigates the removal of arsenic from water using an environmentally friendly modified biosorbent, chitosan coated with Fe-Mn binary oxide (Chit-FeMn), simply prepared with an one-pot low-cost procedure by simultaneous oxidation and coprecipitation. The sorbent was characterized by SEM, EDS, XRD, FTIR, BET specific surface area, and point of zero charge (pH pzc) measurements. The kinetic data fitted a pseudo-second order model for both As(III) and As(V), suggesting chemical adsorption on the sorbent surface and that intra-particle diffusion is not the only rate-limiting step during adsorption. The adsorption isotherms were best fit to the Freundlich model, and the non-monolayer adsorption model for arsenic on Chit-FeMn is therefore proposed. Below pH 9, the effect of pH on As(III) and As(V) removal by Chit-FeMn was insignificant, with As removals remaining above 85 %. Cland NO 3 had negligible influences on As(III) and As(V) removal, whereas PO 4 3-, SiO 3 2-, CO 3 2and SO 4 2were observed to compete with arsenic species for adsorption sites. The adsorbent was successfully applied to remove arsenic from real arsenic contaminated groundwater samples to below 10 µg L-1 suggesting that Chit-FeMn is a promising candidate for the low cost removal of both As(V) and As(III) during drinking water treatment.

The removal of arsenic from groundwater by continuous electrocoagulation (EC) using combined Fe-Al electrodes at its natural temperature (16.1±0.2 °C) was comprehensively evaluated. The results obtained indicated that all studied Fe-Al electrode combinations were able to reduce As concentration below 10 μg/dm 3. Nevertheless, the Fe-Fe-Al-Fe electrode combination was the most suitable due to its highest arsenic removal capacity (0.354 µg As/C) for the lowest charge loading 68.4 C/dm 3. The specific consumption of Fe was 0.0339 kg Fe/m 3 and of Al electrodes 0.0145 kg Al/m 3. The operating cost was estimated at 0.182 €/m 3. The increase of the groundwater temperature by 8 °C from its natural temperature influenced increase of the Fe and Al electrodes dissolution rate by 30% and 17%, respectively and that of As removal efficiency by 16%. The residual Fe and Al concentrations in 500 dm 3 of treated groundwater were below WHO guideline values for drinking water. Long-term field operation of the pilot-scale continuous EC reactor is required to validate effectiveness, reliability and robustness of the EC technique for arsenic removal from groundwater confirmed in laboratory conditions.