| The author recognizes that the presence of arsenic in surface and ground waters is generally accompanied by the presence of iron. Any effort for arsenic removal from water should be directed toward iron removal as well, which was the purpose of this research.; Iron and arsenic removal was studied using tap water to which 0.2 mg/l As(III) and 1.0 mg/l Fe(II) were added. The pH of this water was 8.03 (+OR-) 0.17.; Four oxidants were tested for simultaneous removal of iron and arsenic. These oxidants were: ozone, oxygen, sodium hypochlorite and potassium permanganate. It was found that the order of effectiveness for simultaneous removal of both iron and arsenic was: KMnO(,4) > O(,3) > NaOCI > O(,2). The corresponding percentage arsenic removal after oxidation by these exidants and filtration through a 0.45 mm membrane filter were: 46 > 40 > 14 > 7 while corresponding figures for iron removal were 50 > 43 > 22 > 17.; After oxidation by KNnO(,4), NaOCl or O(,3), coagulation, settling and membrane filtration, the following inorganic coagulants were found to be most effective for removal of arsenic: CuSO(,4), CuCl, ZnCl(,2), FeSO(,4) and Fe(,2)(SO(,4))(,3). The arsenic removal by these coagulants was 75-88%.; Also the following polyelectrolytes were found to be effective for removal of arsenic; Nalcolyte-IWE-2168 and IWE-SSCP-2. The arsenic removal by these polyelectrolytes was 61-62% and the iron removal was 69-100%.; Iron and arsenic removal by filtration through different filter media after oxidation and coagulation were tested. These filter media were sand, anthracite coal and activated carbon. Iron and arsenic removal were dependent on the different combination of the oxidants, coagulants and filter media used. It is found that the following processes can reduce iron and arsenic level below their permissible levels in drinking water: (a) Oxidation by NaOCl or KMnO(,4), coagulation by IWE-2168 and anthracite coal filtration. (b) Oxidation by NaOCl or KMnO(,4), coagulation by FeCl(,3), and sand/activated carbon filtration. (c) Oxidation by KMnO(,4), coagulation by FeCl(,3) and anthracite coal filtration. (d) Oxidation by NaOCl or KMnO(,4), coagulation with ZnCl(,2), and filtration through sand, anthracite coal or sand/activated carbon filter. |
