Performance of conventional starches as natural coagulants for turbidity removal

Sook Yan Choy, Krishnamurthy Nagendra Prasad, Ta Yeong Wu, Mavinakere Eshwaraiah Raghunandan, Ramakrishnan Nagasundara Ramanan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)


The efficiency of rice, wheat, corn and potato starches in removing turbidity was performed and compared to alum and polyaluminium chloride. Using kaolin suspensions, the effects of pH, dosage and need for starch gelatinization was studied. Autoclaved rice starch with larger polymer chain length outperformed other starches to yield 50% turbidity removal with an optimized dosage of 120 mg/L and initial pH of 4 at a sedimentation time of 30 min. The integrated use of autoclaved rice starch and chemical coagulants as a two step coagulation process has further increased the efficiency of turbidity removal by at least 30%. This process has also reduced the amount of chemical-based sludge by 60% which was highly favourable. SEM images of starch treated flocs revealed distinct bridging of kaolin particles in-line with properties of respective coagulation mechanisms specifically adsorption and bridging. This study further conduces to the understanding of starches as coagulants and puts forward a basis for the characterization of resulting flocs.

Original languageEnglish
Pages (from-to)352-364
Number of pages13
JournalEcological Engineering
Early online date20 Jun 2016
Publication statusPublished - Sept 2016


  • Alum
  • Coagulation-flocculation
  • Floc characteristics
  • Natural coagulant
  • PACl
  • Starch

ASJC Scopus subject areas

  • Environmental Engineering
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law


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