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German research project develop analysis procedure for biogas substrates

Together with renowned German research partners, the biology department of Weltec Biopower is developing a quick test for identifying inhibitors in biogas substrates.

Together with partners Weltec Biopower is developing a new biogas substrate test procedure (photos courtesy Hölzen/Weltec).
Together with partners Weltec Biopower is developing a new biogas substrate test procedure (photos courtesy Hölzen/Weltec). Together with partners Weltec Biopower is developing a new biogas substrate test procedure (photos courtesy Hölzen/Weltec).

An on-going concern for biogas plant operators is that an incoming substrate may contain substances that prevent efficient biogas production. For example, a small amount of mould is sufficient to cause such an adverse effect in silage. Ammonium, copper, zinc, pharmaceuticals and disinfectants are often identified as inhibitors in slurry and manure. Even traces of these substances are detrimental to the bacteria in the digester and thus counterproductive to the digestion process. Therefore, it is absolutely necessary to identify such inhibitors before transferring the substances into the digester.

Develop new test procedure

Since December 2016, German biogas technology specialist Vechta-based Weltec Biopower GmbH is involved in a collaborative research project to establish a new test procedure that will better address this problem. Initiated in collaboration with the Göttingen University of Applied Sciences and Art (HAWK), Weltec is developing a quick, reliable and inexpensive procedure for identifying inhibitors in input substances.

The Fraunhofer UMSICHT Institute in Oberhausen and Berlin-based analytics specialist aokin AG are also involved in the project, which is supported by the German Federal Ministry of Food and Agriculture (BMEL) via its Agency for Renewable Resources (Fachagentur Nachwachsende Rohstoffe e.V.)

– The need and demand are on hand. Currently, there is no quick and reliable way to identify such potential process disruptions, though this would be vital to avoid unscheduled downtimes of biogas plants, explained Sabine Lampe, graduate biologist and supervisor of the research project at Weltec Biopower outlining the project background.

Replace aerobic dairy test

Various feedstocks are first examined in the Weltec laboratory in Vechta and at HAWK in Göttingen with the help of the Ankom system. This system delivers precise information on the gas production. Moreover, the change of the acid spectrum is monitored while deliberately adding inhibitors. The resulting target curves are then compared with the gas production curves of substrates. This comparison is to reveal whether the substrate contains any inhibitors.

Previously, the aerobic four-plate inhibitor test was used to for identifying inhibitors though this test is designed for the dairy industry and does not reflect the conditions in the digester. Therefore, the test results are not as relevant as they should be. With the new anaerobic procedure, results are to be available after three days. In this way, biogas plant operators will be able to determine the quality of their input materials precisely, speedily and inexpensively.

– Based on this innovative procedure, biogas plant operators will be able to decide faster whether to buy offered silage or liquid manure or whether to use a certain batch of their own slurry, explained Sabine Lampe adding that it would also be possible for substrate providers to use this quick test to provide evidence of product quality.

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