Rein and Associates

Our firm specializes in water/wastewater process engineering, plant operations, and asset management. Because we specialize in water and wastewater systems, we have the ability to provide services for project inception, design, start-up and continuing operations. Our clients include commercial, industrial and governmental entities.

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Since September 2006, Rein & Associates has been investigating the potential for extracting additional energy from stillage produced at corn based ethanol production facilities. It was first demonstrated, on a bench scale, that “thick stillage” was an ideal feedstock for biologically producing methane gas (a green replacement for natural gas).

Based on the early bench scale success, funding for additional full scale and pilot scale work was sought and provided by the Agricultural Utilization and Research Institute (AURI), the Minnesota Corn Growers Association, Otter Tail Power and the City of Fergus Falls.

Phase I was a full scale demonstration conducted at the Fergus Falls Wastewater Treatment Plant using thick stillage as an additional bio-feed stock for the City’s anaerobic digesters. This project successfully demonstrated that thick stillage could be used to produce sufficient additional biogas to completely satisfy the natural gas demand at the wastewater treatment plant.

Phase II has been a pilot scale demonstration conducted at the Fergus Falls Wastewater Treatment Plant; however, this time “thin stillage” was the bio-feed stock and the digestion was conducted in a 10,000 gallon pilot plant. This phase of the project demonstrated that sufficient biogas could be produced from thin stillage to allow for the production of ethanol without the use of fossil fuels. It also demonstrated the potential for producing a renewable slow release fertilizer, struvite.

Phase III of the project has also been conducted at the Fergus Falls Wastewater Treatment Plant. Its purpose has been to demonstrate the feasibility of producing struvite, along with biogas, at an ethanol production facility. A skid mounted struvite production pilot plant was used for this demonstration. Preliminary analysis of the results indicates that the production of struvite, along with biogas, would be feasible. A Phase III report is being prepared that will present the findings and conclusions for this phase of the project.