Jack Ruhland, ISU Civil Engineering major, was funded by C-Change to understand the feasibility of using herbaceous biomass as additive to municipal anaerobic digesters, with the focus on improving the natural gas production. Jack collaborated with staff at the Ames Water Pollution Control (WPC) Facility to conduct the assessment. He specifically used switchgrass as the source of herbaceous biomass and conducted a series of experiments to understand logistics and cost-effectiveness of adding switchgrass to the municipal digester.

Jack determined that adding switchgrass biomass directly to the digesters would not be feasible for two reasons. First, it would not be feasible economically given the value per volume of natural gas produced. Second, it would not be feasible technically due to the hardy nature of the biomass causing significant clogging issues. Herbaceous biomass would require pretreatment in order to be feasible to add to a municipal digester. Follow up research is needed to understand pretreatment options and feasibility.

Find Jack's full report, here.

Additional findings supported by the Walton Family Foundation grant can be found here.