Water utilities in Japan want to reduce residual chlorine levels so as to reduce disinfection byproducts and the chlorine smell, but bacterial regrowth is a concern. In advanced water treatment plants using ozonation and biological activated carbon (BAC), BAC plays the most important role in reducing assimilable organic carbon (AOC). Therefore, we analyzed the removal of dissolved organic matter (DOM) and AOC by full-scale BAC filters with different operational periods. Seasonal variation in AOC in raw water was wide, with a maximum of 306 μg acetate-C/L in November, and ozonation increased AOC. Nonetheless, BAC filters that had operated for 6 years produced water with lower AOC than ones with shorter operational periods, although they released a small amount of aromatic DOM. A diagram was constructed to derive the required levels of residual chlorine for no bacterial regrowth at various AOC levels of BAC effluents, which were linked with the operational periods of BAC filters and AOC in the ozonation effluents. Although BAC filters operated for longer than 100 weeks can effectively reduce AOC, lowering AOC levels in the ozonation effluent was indispensable for preventing bacterial regrowth in the water supply network at lower levels of residual chlorine than at present.
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Research Article|
September 12 2013
Removal of DOM and AOC in a full-scale advanced water treatment plant: effects of operational periods of BAC filters
J. Lohwacharin
;
1
Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
E-mail: jenyuk@env.t.u-tokyo.ac.jp
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Y. Yang
;
Y. Yang
2
School of Environmental Engineering, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875, China
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N. Watanabe
;
N. Watanabe
3
Division of Energy and Environmental Systems, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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A. Phetrak
;
A. Phetrak
1
Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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S. Takizawa
S. Takizawa
1
Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Water Supply (2014) 14 (1): 165-172.
Article history
Received:
February 26 2013
Accepted:
July 16 2013
Citation
J. Lohwacharin, Y. Yang, N. Watanabe, A. Phetrak, S. Takizawa; Removal of DOM and AOC in a full-scale advanced water treatment plant: effects of operational periods of BAC filters. Water Supply 1 February 2014; 14 (1): 165–172. doi: https://doi.org/10.2166/ws.2013.185
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J. Lohwacharin, Y. Yang, N. Watanabe, A. Phetrak, S. Takizawa; Removal of DOM and AOC in a full-scale advanced water treatment plant: effects of operational periods of BAC filters. Water Supply 1 February 2014; 14 (1): 165–172. doi: https://doi.org/10.2166/ws.2013.185
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