Scum to biodiesel pilot system.

MN Impact: New Pilot System Turns Scum Into Biodiesel

August 28, 2018


Research will investigate and help develop novel sources of bioenergy.


Scum, a dark, muddy substance produced during wastewater treatment, presents a significant waste disposal challenge but a potential energy source.

What has been done

Roger Ruan and his colleagues at the Center for Biorefininghave been working on developing a system to turn scum into biodiesel. Their aim is to streamline the disposal process of scum, while maximizing biodiesel output, moving toward complete utilization of liquid and solid wastes. The team developed a pilot system and tested it using scum from the St. Paul wastewater treatment facility at the Rosemount ROC.


The pilot system found 68 percent of the dried and filtered scum could be converted to biodiesel. This is equivalent to approximately 140,000 gallons of biodiesel and $500-600 thousand in profit per year using all the scum from the St. Paul wastewater treatment plant. Notably, this patented process not only converts scum to biodiesel but also reduces environmental pollutants in both landfills and water systems.