Innovative test method for the estimation of the foaming tendency of substrates for biogas plants

[Display omitted] •Foaming in biogas plants depends on the interactions between substrate and digestate.•Foaming tests enable the evaluation of substrate foaming tendency in biogas plants.•Leipzig foam tester enables foaming tests of substrates prior to use. Excessive foaming in anaerobic digestion occurs at many biogas plants and can cause problems including plugged gas pipes. Unfortunately, the majority of biogas plant operators are unable to identify the causes of foaming in their biogas reactor. The occurrence of foaming is often related to the chemical composition of substrates fed to the reactor. The consistency of the digestate itself is also a crucial part of the foam formation process. Thus, no specific recommendations concerning substrates can be given in order to prevent foam formation in biogas plants. The safest way to avoid foaming is to test the foaming tendency of substrates on-site. A possible solution is offered by an innovative foaming test. With the help of this tool, biogas plant operators can evaluate the foaming disposition of new substrates prior to use in order to adjust the composition of substrate mixes.