Degradation Of Humic Acid By UVC/Fenton Process And Other Photochemical Oxidation Technologies

Humic acids?HAs?are the common components of natural organic matter?NOM?in drinking water sources,and the removal of HA is one of the main goals in the drinking water treatment,because HA can cause taste,odor,and the regrowth of bacteria in the water supplies.Besides,they can also form carcinogenic byproducts upon the reaction of chlorine in the sterilization process using chlorine,such as trihalomethanes?THMs?and haloacetic acids?HAAs?,which have posed great threat in drinking water treatment and have attained increasing attention of Chinese government concerns in recent years.In this study,HA extracted from the Pearl River sediments was treated by UVC/Fenton process and other photochemical oxidation technologies based on short-wave ultraviolet?UVC?and vacuum ultraviolet?VUV?.The study include: the optimization of key factors affecting the removal of HA by UVC/Fenton process and the comparison of the removal of HA by different photochemical oxidation technique..FTIR spectra of HAs showed that the HAs extracted from the Pearl River were the complex organic compounds contained carboxyl,carbonyl and aromatic hydrocarbons et al,and it was a mixture of polymers of poorly known structure.Results showed the values of 61.9% mineralization of HA and 100% reduction of UV absorbance at 254nm(UV₂₅₄)were achieved after 8 h reaction,which indicated that HA was not completely oxidized to carbon dioxide,but rather transformed to some organic intermediates during the UVC/Fenton process.After 14 h of treatment,the TOC of the HA solution decreased from 10 to 3.4 mg/L?the degree of mineralization was of 66%?.On other hand,biodegradability enhancement was observed during the UVC/Fenton process,measured by the ratio of biodegradable TOC?BTOC?at 5 days and initial TOC?BTOC/TOC?,which increased from 0.13 to 0.65.Based on these results,in combination with biological technology,the UVC/Fenton process could be applied to the removal of organic matter in water contaminated by HA from the Pearl River.The removal of HA by different photochemical oxidation technologies based on UVC or VUV were carried out.Based on the guideline values of TOC in USEPA regulation,there are 8 different treatment processes can be used for the removal of HA in water,and further analysis of the 8 different treatment processes showed the VUV photodegradation process and VUV photodegradation combined with biological technology had the advantages of simple treatment scheme and reagent consumption;Besides,after 2 h treatment of UVC/Fenton process,VUV photodegradation,VUV/H₂O₂ process and VUV/Fenton process,the THMs formed could decreased below 80?g/L by the subsequent chlorination.Based on those results,VUV photodegradation process and VUV photodegradation combined with biological technology could be the economic and effective processes to applied for the removal of organic matter in water contaminated by HA from the Pearl River.