The occurrence of arsenic (As) in groundwater in fourteen villages in Houshayu Town, Shunyi District, Beijing, China, was investigated, and a column experiment for the removal of As was conducted on-site with a pellet type iron-cerium (Fe-Ce) bimetal oxide adsorbent prepared in lab. The As concentration in the groundwater of twelve villages exceeds the maximum contamination level (10 µg/L) of the World Health Organization, and two of them exceed that of China (50 µg/L). A column experiment at a space velocity of 3 h-1 shows that the Fe-Ce adsorbent could remove As(V) (total As, 71 ± 19.7 µg/L) from groundwater with high efficiency. Around 11,500 bed volumes were gained when As(V) in the effluent exceeds 10 µg/L, giving an accumulated adsorption capacity of 6.0 mg As(V)/g adsorbent. Both batch tests and the column test suggest that humic substances might compete with As(V) for the adsorption sites, which disappeared after the column was continuously operated for more than two weeks. The effluent quality including heavy metals, radioactivity, etc., was confirmed to meet the drinking water standards of WHO and China.
A pilot plant with successive preozonation, coagulation-sedimentation, sand filtration, postozonation, and biological activated carbon was operated for more than six months to treat reservoir water containing 15-38 µg/L of bromide in southern China. Preozonation enhanced the removal of chemical oxygen demand using potassium permanganate as the oxidant (COD Mn ) and ultraviolet light absorbance at 254 nm (UV 254 ) using coagulationsedimentation but did not improve total organic carbon (TOC)-removal effectively. However, preozonation markedly enhanced the removal of trihalomethane formation potential (THMFP) by the conventional process, and THMFP removal by the combination of preozonation and conventional treatment was 57% using an ozone dose of 0.8 mg/L. Almost no bromate formed during preozonation. An ozone dose of 2.0 mg/L (0.5 mg/L and 1.5 mg/L for pre-and postozonation, respectively) was found to be the optimal dosage for the maximum removal of organics (65% of THMFP, 52% of TOC, 63% of COD Mn , and 84% of UV 254 ) while keeping bromate under 5 µg/L. A combination of conventional treatment with preozonation should be a suitable alternative if the primary goal is to remove THMFP.
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