Tham khảo tài liệu 'studies on water management issuese part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 230 Studies on Water Management Issues transport the metals into the environment and also contribute to pipe corrosions Motheo Pinhedo 2000 . Besides HS can also act as a source of methyl groups and hence react with hypochlorite ions which are being used as biocide in water treatment plants to produce disinfectant by-products. Examples of these by-products are trihalomethanes haloacetic acids other chlorinated compounds and nitriles. Some of these by-products are suspected to be carcinogenic. Till date more than 150 products have been recognized as the products of the reaction between HS and chlorine. The advance oxidation process has been implemented to decrease the organic matter in water including the HS. Its major advantage is that the advance oxidation process does not produce any toxic by-products or residues which required further treatment or disposal. Till date the degradation of HS using photocatalytic process has not been studied well. The very first study based on this was carried out by Bekbolet in 1996 who studies the effectiveness of photocatalytic treatment on the degradation of model humic substances or humic acid Bekbolet Ozkosemen 1996 . Bekbolet and Ozkosemen studied about the degradation via photocatalytic process using humic acid as a model pollutant. Through the experiment they found out that after one hour of illumination in the presence of of Degussa P25 40 of the TOC and 75 of the colour 400nm were removed Bekbolet Ozkosemen 1996 .Bekbolet and co. again studied the removal of colour caused by humic acid in the presence of common inorganic ions . chloride nitrate phosphate and sulphate ions at pH and they found some removal Bekbolet et al. 1998 . In other researches where humic acid was used as an additional matrix for the degradation of some organic pollutants a 80 removal of commercialized humic acid was recorded by using irradiation in the presence of Degussa P25 Minero et al. 1997 . Another similar study showed a reduction .
