title: Comparison between UV and VUV photolysis for the pre- and post-treatment of coking wastewater.
abstract: In this study, ultraviolet (UV) and vacuum ultraviolet (VUV) photolysis were investigated for the pre-treatment and post-treatment of coking wastewater. First, 6-fold diluted raw coking wastewater was irradiated by UV and VUV. It was found that 15.9%-35.4% total organic carbon (TOC) was removed after 24 hr irradiation. The irradiated effluent could be degraded by the acclimated activated sludge. Even though the VUV photolysis removed more chemical oxygen demand (COD) than UV, the UV-irradiated effluent demonstrated better biodegradability. After 4 hr UV irradiation, the biological oxygen demand BOD5/COD ratio of irradiated coking wastewater increased from 0.163 to 0.224, and its toxicity decreased to the greatest extent. Second, the biologically treated coking wastewater was irradiated by UV and VUV. Both of them were able to remove 37%-47% TOC within 8 hr irradiation. Compared to UV, VUV photolysis could significantly improve the transparency of the bio-treated effluent. VUV also reduced 7% more ammonia nitrogen (NH4+-N), 17% more nitrite nitrogen (NO2--N), and 18% more total nitrogen (TN) than UV, producing 35% less nitrite nitrogen (NO3--N) as a result. In conclusion, UV irradiation was better in improving the biodegradability of coking wastewater, while VUV was more effective at photolyzing the residual organic compounds and inorganic N-species in the bio-treated effluent.
authors.affiliation: College of Environmental Sciences and Engineering, Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University, Beijing 100871, China; CECEP Liuhe and Talroad Environmental Technology Co., Ltd, Beijing 100085, China. Electronic address: rui.xing@talroad.com.cn.
authors.forename: Rui
authors.initials: R
authors.lastname: Xing
authors.affiliation: College of Environmental Sciences and Engineering, Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University, Beijing 100871, China.
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: College of Environmental Sciences and Engineering, Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University, Beijing 100871, China. Electronic address: dhwen@pku.edu.cn.
authors.forename: Donghui
authors.initials: D
authors.lastname: Wen
mesh_terms: D019149:Bioreactors; D003077:Coke / Q000032:analysis*; D007220:Industrial Waste; D010782:Photolysis; D014466:Ultraviolet Rays; D014618:Vacuum; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D003077:Coke; D007220:Industrial Waste; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Coking wastewater; Post-treatment; Pre-treatment; UV; VUV