Process development for scum to biodiesel conversion

Chong hao Bi, Min Min, Yong Nie, Qing long Xie, Qian Lu, Xiang yuan Deng, Erik Anderson, Dong Li, Paul Chen, Roger Ruan

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


A novel process was developed for converting scum, a waste material from wastewater treatment facilities, to biodiesel. Scum is an oily waste that was skimmed from the surface of primary and secondary settling tanks in wastewater treatment plants. Currently scum is treated either by anaerobic digestion or landfilling which raised several environmental issues. The newly developed process used a six-step method to convert scum to biodiesel, a higher value product. A combination of acid washing and acid catalyzed esterification was developed to remove soap and impurities while converting free fatty acids to methyl esters. A glycerol washing was used to facilitate the separation of biodiesel and glycerin after base catalyzed transesterification. As a result, 70% of dried and filtered scum was converted to biodiesel which is equivalent to about 134,000 gallon biodiesel per year for the Saint Paul waste water treatment plant in Minnesota.

Original languageEnglish (US)
Pages (from-to)185-193
Number of pages9
JournalBioresource Technology
StatePublished - Jun 1 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier Ltd.


  • Acid washing
  • Biodiesel
  • Glycerol washing
  • Scum
  • Wastewater treatment plant


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