Determining the effectiveness of conventional and alternative coagulants through effective characterization schemes

Shahnawaz Sinha, Yeomin Yoon, Gary Amy, Jaekyung Yoon

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


Polymeric forms of metal coagulants in water treatment have become increasingly used due to their wider availability and reduction in cost. These specialized coagulant forms and products are claimed by manufacturers to be superior to conventional coagulants in particulate and/or organic removal with inherent advantages of lower alkalinity consumption and lesser sludge production. However, due to their proprietary nature, little is known about their chemical composition. To determine and understand the effectiveness of these alternative coagulants, a comprehensive study was undertaken to characterize metal coagulants, and to comparatively evaluate them on a well-characterized source water. The objective of this study was to provide a scheme for utilities that could be employed as a screening process and a method of selecting an appropriate coagulant based on raw water characteristics and insight into the coagulatability of the source water. Characterizations of coagulants included: (i) active metal content, (ii) anion content, (iii) acidity, (iv) alkalinity consumption, (v) charge reversal by colloidal titration, and (vi) molecular weight determination. A total of five poly-aluminum chlorides (PACl), along with a conventional coagulant (aluminum sulfate or alum) were evaluated. Results show that through the characterization scheme, an effective coagulant (conventional versus alternative) and coagulant type (among various PACl) can be chosen before undertaking time-consuming bench or pilot-scale evaluation.

Original languageEnglish
Pages (from-to)1115-1122
Number of pages8
Issue number9
StatePublished - Dec 2004

Bibliographical note

Funding Information:
This work was funded by Denver Water; special thanks to Ken Pollack and Steve Lohman of Denver Water and Brad Segal of the City of Boulder, Colorado for their assistance.


  • Alum
  • Coagulation
  • Hydrophobicity
  • NOM size exclusion
  • PACl


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