Mechanism of enhanced coagulation and modified activated carbon on DON in the secondary effluent
LIU Bing1,2, ZHENG Yu-ming2, GU Li3, LI Qing-fei1, YU Guo-zhong1, ZHAI Hui-min1
1. School of Geographic Sciences, Xinyang Normal University, Xinyang 464000, China; 2. Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; 3. College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China
Abstract：In order to explore the mechanism on dissolved organic nitrogen (DON) removal in the secondary effluent of wastewater treatment plant by enhanced coagulation and modified activated carbon adsorption, the molecular weight distribution and hydrophobicity/hydrophilicity of DON were analyzed. Besides, chlorinated disinfection by-product (DBP) formation potential was investigated. Combined with three dimensional (3DEEM), DON compositions and their chemical structures before and after coagulation and adsorption were also studied. The results showed that (1) enhanced coagulation could significantly improve DON removal efficiency, with an increase in DON removal rate of 1.45-fold, 2.06-fold, 2.09-fold and 1.96-fold by pH enhanced coagulation, pre-ozonation enhanced coagulation, PAC enhanced coagulation and PAM enhanced coagulation, respectively; (2) the adsorption process of DON by the activated carbon was better correlated with the quasi-second-order kinetic model. During DON adsorption process, π-π dispersion mechanism mainly exists on the surface of acid-modified activated carbon, and electron donor-acceptor formation mechanism is present on the surface of alkali modified activated carbon; (3) after the enhanced coagulation and activated carbon adsorption, the molecular weight and composition of DON changed greatly, and DBP formation potential decreased significantly; (4) finally, the 3DEEM and fluorescence spectral region volume integral analysis suggested DON concentration and DBP formation potential were related with the fluorescent regions Ⅱ and IV in enhanced coagulation and activated carbon adsorption process.
刘冰, 郑煜铭, 古励, 李清飞, 余国忠, 翟慧敏. 强化混凝和改性活性炭对二级出水DON的作用机制[J]. 中国环境科学, 2018, 38(1): 136-149.
LIU Bing, ZHENG Yu-ming, GU Li, LI Qing-fei, YU Guo-zhong, ZHAI Hui-min. Mechanism of enhanced coagulation and modified activated carbon on DON in the secondary effluent. CHINA ENVIRONMENTAL SCIENCECE, 2018, 38(1): 136-149.
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