A specially designed combined process of pre-oxidation and nanofiltration membrane was utilized to remove As(III) in the contaminated water without reagent addition and sediment creation in this work. Different parameters that affected the rejections of As(III) and As(V) were discussed, including the initial concentration, pH of the feed, and the cross-flow filtration pressure. The rejection of As(III) was over 70% which was restricted to the high initial feed concentration, while it was around 40% under the other conditions. Whereas, the rejection of As(V) maintained above 95% in all tests. As a result, As(III) was first pre-oxidized before membrane filtration. The ozone and aeration oxidation methods were used to oxidize As(III). The effects of aeration time and oxidation time were studied. The experimental results indicated that the rejection of As(III) was increased to over 90% after pre-oxidation, and the permeate could meet the drinking water standard for As in China. Particularly, the aeration took a much longer oxidation time than ozone, but it was still a more suitable method as the pre-oxidation process because of its safety and easy operability.
Chlorine dioxide (ClO 2 ) has been widely used in the process of preoxidation and disinfection as an excellent water treatment reagent. However, the inorganic by-products produced by ClO 2 , such as chlorite (ClO 2 − ) and chlorate (ClO 3 − ) are harmful to human health, and this has become a potential problem when using ClO 2 in drinking water treatment. In this study, ClO 2 alone and a ClO 2 /NaClO combination process were carried out to evaluate the algae removal efficiency of the treatment and the formation of disinfection by-products (DBPs: chlorite, chlorate, trihalomethanes and haloacetic acids) for high algae-laden water with 124.16 µg L −1 chlorophyll a (Chl.a) content. The results show that disinfection with 1.5 mg L −1 ClO 2 alone results in a ClO 2 − concentration exceeding 0.7 mg L −1 . ClO 2 preoxidation/ClO 2 disinfection is applicable for the control of effluent quality, but the ClO 2 − concentration still has an excessive risk when using 0.8 mg L −1 and 0.6 mg L −1 ClO 2 for the two process, respectively. In the ClO 2 /NaClO combination process, the ClO 2 − concentration is below 0.6 mg L −1 , and trihalomethane (THM) and haloacetic acid (HAA) concentrations are lower than 60% of the maximum contaminant levels (MCLs) set by the World Health Organization (WHO). Further, the formation of ClO 2 − is more effectively controlled by NaClO preoxidation/ClO 2 disinfection than ClO 2 preoxidation/NaClO disinfection.
危险品化学品经营许可证（带存储）