Chinese Science Bulletin

, Volume 55, Issue 14, pp 1382–1387 | Cite as

Effects of pH on coagulation behavior and floc properties in Yellow River water treatment using ferric based coagulants

  • BaiChuan Cao
  • BaoYu Gao
  • ChunHua Xu
  • Ying Fu
  • Xin Liu
Articles Environmental Chemistry

Abstract

Enhanced coagulation is one of the major methods to control disinfection by-products (DBPs) in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects and mechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymer coagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole coagulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above.

Keywords

ferric based inorganic polymer coagulants pH coagulation effect floc formation floc breakage and re-growth 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Pontius F W. Regulations in 2000 and beyond. J Am Water Works Assoc, 2000, 92: 40–54Google Scholar
  2. 2.
    Lu G J, Huang Z C, Duan J H. Principle and application for a new method of high effective strengthen flocculation (in Chinese). J Tsinghua Univ (Sci & Technol), 2000, 40: 114–116Google Scholar
  3. 3.
    Li F T. Progress of inorganic coagulant-poly ferric sulfate in China (in Chinese). Industrial Water Treatment, 2002, 22: 5–8Google Scholar
  4. 4.
    Wang D S, Tang H X. Cogulation behavior of new IPE-PFSi (in Chinese). Acta Scientiae Circumstantiae, 2001, 21: 37–42Google Scholar
  5. 5.
    Gao B Y, Song Y H, Yue Q Y. Performance of polysilicic ferric sulfate coagulant (in Chinese). Environ Sci, 1993, 7: 46–48Google Scholar
  6. 6.
    Zhang S, Xie S G, Zhang X J, et al. The study progress of the control of natural organic matter in raw water by enhanced coagulation (in Chinese). Tech Equip Environ Pollut Control, 2003, 4: 19–22Google Scholar
  7. 7.
    Kimberly B A, Abbaszadegan M, Ibrahim E, et al. Conventional and optimized coagulation for NOM removal. J Am Water Works Assoc, 2000, 92: 44–58Google Scholar
  8. 8.
    Boller M, Blaser S. Particles under stress. Water Sci Technol, 1998, 37: 9–29Google Scholar
  9. 9.
    Zhang Z G, Luan Z K, Zhao Y, et al. Breakage and regrowth of flocs coagulation with polyaluminum chloride (PACl) (in Chinese). Environ Sci, 2007, 28: 346–351Google Scholar
  10. 10.
    Yu W Z, Li G B, Xu Y P, et al. Breakage and re-growth of flocs formed by alum and PACl. Powder Technol, 2009, 189: 439–443CrossRefGoogle Scholar
  11. 11.
    Sharp E L, Jarvis P, Parsons S A, et al. The impact of zeta potential on the physical properties of ferric-NOM flocs. Environ Sci Technol, 2006, 40: 3934–3940CrossRefGoogle Scholar
  12. 12.
    Francois R J. Strength of aluminium hydroxide flocs. Water Res, 1987, 21: 1023–1030CrossRefGoogle Scholar
  13. 13.
    Yukselen M A, Gregory J. The reversibility of floc breakage. Int J Miner Process, 2004, 73: 251–259CrossRefGoogle Scholar
  14. 14.
    Wei J C, Gao B Y, Yue Q Y, et al. Comparison of coagulation behavior and floc structure characteristic of different polyferric-cationic polymer dual-coagulants in humic acid solution. Water Res, 2009, 43: 724–732CrossRefGoogle Scholar
  15. 15.
    Fu Y, Yu S L, Yu Y Z, et al. Quantitative investigation on flocculation and destruction of poly-silicic-ferric (PSF) coagulant (in Chinese). Environ Sci, 2008, 29: 92–98Google Scholar
  16. 16.
    Tipping E, Reddy M M, Hurley M A. Modelling electrostatic and heterogeneity effects on proton dissociation from humic substances. Environ Sci Technol, 1990, 24: 1700–1705CrossRefGoogle Scholar
  17. 17.
    Julien F, Güeroux B, Mazet M. Comparison of organic compounds removal by coagulation-flocculation by adsorption onto performed hydroxide flocs. Water Res, 1994, 28: 2567–2574CrossRefGoogle Scholar
  18. 18.
    Jarvis P, Jefferson B, Gregory J, et al. A review of floc strength and breakage. Water Res, 2005, 39: 3121–3137CrossRefGoogle Scholar
  19. 19.
    Yukselen M A, Gregory J. The effect of rapid mixing on the break-up and re-formation of flocs. J Chem Technol Biotechnol, 2004, 79: 782–788CrossRefGoogle Scholar
  20. 20.
    Fu Y, Yu S L. Hydrolysis law and coagulation mechanism of poly-silicic-ferric sulfate (PSF) coagulant (in Chinese). Environ Sci, 2007, 28: 113–119Google Scholar
  21. 21.
    Qiu J M, Qiu Z M. The progress of iron-modified polysilicate salt flocculants (in Chinese). Jiangxi Chem Ind, 2003, 1: 1–3Google Scholar
  22. 22.
    Gregory D, Carlson K. Relationship of pH and floc formation kinetics to granular media filtration performance. Environ Sci Technol, 2003, 37: 1398–1403CrossRefGoogle Scholar

Copyright information

© Science in China Press and Springer Berlin Heidelberg 2010

Authors and Affiliations

  • BaiChuan Cao
    • 1
  • BaoYu Gao
    • 1
  • ChunHua Xu
    • 1
  • Ying Fu
    • 2
  • Xin Liu
    • 1
  1. 1.Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and EngineeringShandong UniversityJinanChina
  2. 2.School of Civil and ArchitectureJinan UniversityJinanChina

Personalised recommendations