Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

doi:10.1016/S1004-9541(13)60463-2

Chinese Journal of Chemical Engineering ›› 2013, Vol. 21 ›› Issue (3): 318-323.DOI: 10.1016/S1004-9541(13)60463-2

• 能源、资源与环境技术 • 上一篇下一篇

Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

张忠国¹, 刘丹¹, 胡丹丹², 李多¹, 任晓晶¹, 程言君¹, 栾兆坤³

1 Environmental Protection Research Institute of Light Industry, Beijing Academy of Science and Technology, Beijing 100089, China ;
2 Beijing Academy of Science and Technology, Beijing 100089, China ;
3 State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences，Beijing 100085, China

收稿日期:2012-05-27 修回日期:2012-08-06 出版日期:2013-03-28 发布日期:2013-04-01
通讯作者: ZHANG Zhongguo,REN Xiaojing
基金资助:
Supported by the National High Technology Research and Development Program of China (2009AA063901), the Special Funds for Technological Development of Research Institutes from the Ministry of Science and Technology of China (2010EG111022, 2011EG111307), and the Budding Program (2011A-12-L) and the Program for Innovative Research Team (IG201204N) of Beijing Academy of Science and Technology.

Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

ZHANG Zhongguo¹, LIU Dan¹, HU Dandan², LI Duo¹, REN Xiaojing¹, CHENG Yanjun¹, LUAN Zhaokun³

1 Environmental Protection Research Institute of Light Industry, Beijing Academy of Science and Technology, Beijing 100089, China ;
2 Beijing Academy of Science and Technology, Beijing 100089, China ;
3 State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences，Beijing 100085, China

Received:2012-05-27 Revised:2012-08-06 Online:2013-03-28 Published:2013-04-01
Supported by:
Supported by the National High Technology Research and Development Program of China (2009AA063901), the Special Funds for Technological Development of Research Institutes from the Ministry of Science and Technology of China (2010EG111022, 2011EG111307), and the Budding Program (2011A-12-L) and the Program for Innovative Research Team (IG201204N) of Beijing Academy of Science and Technology.

摘要/Abstract

摘要： Conventional jar tests and on-line size monitoring were used to investigate the effects of slow-mixing intensity and duration on residual turbidity and floc size during charge neutralization coagulation and sweep flocculation with polyaluminum chloride. The compensatory effect of slow-mixing on coagulation performance following inadequate or excessive rapid-mixing was also examined. It is found that slow-mixing intensity has a more marked positive effect on charge neutralization coagulation than on sweep flocculation. The optimal root-mean- square velocity gradient, G, for slow-mixing is 15 s^-1 for both coagulation mechanisms, and charge neutralization coagulation requires a longer slow-mixing duration. The optimal slow-mixing duration, based on residual turbidity, is longer than the time to form the largest mean flocs. The optimal product of G and mixing duration, GT, for slow-mixing during charge neutralization coagulation (13500) are higher than that during sweep flocculation (4500) and both are less than the range of values recommended by the American Water Works Association (24000-84000). The optimal GT value under various slow-mixing conditions increases with G. Appropriate extension of slow-mixing duration during charge neutralization coagulation can improve coagulation performance after an inadequate or excessive rapid-mixing duration, but during sweep flocculation, appropriate shortening of slow-mixing duration after an excessive rapid-mixing or appropriate extension of slow-mixing duration after an inadequate rapid-mixing is favorable.

关键词: slow-mixing, polyaluminum chloride, charge neutralization coagulation, sweep flocculation, GT value

Abstract: Conventional jar tests and on-line size monitoring were used to investigate the effects of slow-mixing intensity and duration on residual turbidity and floc size during charge neutralization coagulation and sweep flocculation with polyaluminum chloride. The compensatory effect of slow-mixing on coagulation performance following inadequate or excessive rapid-mixing was also examined. It is found that slow-mixing intensity has a more marked positive effect on charge neutralization coagulation than on sweep flocculation. The optimal root-mean- square velocity gradient, G, for slow-mixing is 15 s^-1 for both coagulation mechanisms, and charge neutralization coagulation requires a longer slow-mixing duration. The optimal slow-mixing duration, based on residual turbidity, is longer than the time to form the largest mean flocs. The optimal product of G and mixing duration, GT, for slow-mixing during charge neutralization coagulation (13500) are higher than that during sweep flocculation (4500) and both are less than the range of values recommended by the American Water Works Association (24000-84000). The optimal GT value under various slow-mixing conditions increases with G. Appropriate extension of slow-mixing duration during charge neutralization coagulation can improve coagulation performance after an inadequate or excessive rapid-mixing duration, but during sweep flocculation, appropriate shortening of slow-mixing duration after an excessive rapid-mixing or appropriate extension of slow-mixing duration after an inadequate rapid-mixing is favorable.

Key words: slow-mixing, polyaluminum chloride, charge neutralization coagulation, sweep flocculation, GT value

张忠国, 刘丹, 胡丹丹, 李多, 任晓晶, 程言君, 栾兆坤. Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)[J]. Chinese Journal of Chemical Engineering, 2013, 21(3): 318-323.

ZHANG Zhongguo, LIU Dan, HU Dandan, LI Duo, REN Xiaojing, CHENG Yanjun, LUAN Zhaokun. Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)[J]. Chin.J.Chem.Eng., 2013, 21(3): 318-323.

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Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

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