Removal of arsenic and natural organic matter from groundwater using ferric and alum salts: a case study of central Banat region (Serbia).

This paper presents a comparison of the efficacy of three different coagulants (polyaluminium chloride (PACl), Aluminium sulphate (Al(2)(SO(4))(3)) and ferrous chloride (FeCl(3))) for natural organic matter and arsenic (As) removal from groundwater. Coagulation efficacy was evaluated for the coagulants alone and for combinations of them (PACl/FeCl(3); Al(2)(SO(4))(3)/FeCl(3)), on the basis of changes in dissolved organic matter (DOC) and arsenic content. For single coagulants, PACl (30 mg Al/L) showed optimal efficacy for DOC removal (57%, relative to raw water). The highest arsenic reduction (< 5 microg As/L in coagulated water) was achieved when a very high 300 mg/L dose of FeCl(3) was used. However, if PACl (30 mg Al/L) and FeCl(3) (10 mg FeCl(3)/L) are combined, the efficacy of DOC removal increases compared to PACl and FeCl(3) alone under similar doses (66% decrease in DOC relative to raw water). The DOC and As contents of the coagulated water after application of these doses were 2.26 mg C/L and 9.7 microg/L, respectively, compared to 6.44 mg C/L and 60.5 microg As/L measured in the raw groundwater. The combination of Al(2)(SO(4))(3) and FeCl(3) did not show any improvement in DOC and As removal efficacy relative to using those coagulants alone.