A food waste digester case study from Azura Associates was incorporated into the training material presented by anaerobic digester experts Dr. Melanie Hecht and Birgit Pfeifer at the IBBK’s virtual Biogas Operator Training in June of 2020.
Dr. Hecht, who is a Senior Biogas Plant Biology and Process Control Expert, presented a section called “Practical Plant Operation: Process Control and Plant Optimization” at this event. This case study highlighted the methodology used by Azura to recognize imbalances and proactively adjust the digester feedstock recipe to balance its nutrition for optimal biogas production, performance, and consistency.
The German-based International Biogas and Bioenergy Competence Center (IBBK) is a private anaerobic digester consulting and networking firm. Founded by Michael Kottner, IBBK is focused on promoting biogas projects to support a sustainable future. Due to COVID limitations, this training event was offered virtually from June 22 to June 26, 2020.
Dr. Melanie Hecht, of Schaumann Bioenergy, included a case study drawn from Azura’s work with a food waste market digester receiving a high-FOG feedstock as part of this training. She received her degree in Biological Sciences and a PhD in Agricultural Sciences in biological process optimization of anaerobic digestion plants. She regularly lectures on anaerobic digestion process optimization at various biogas events.
The case study featured the failure of a food waste anaerobic digester between 2018 and 2019. Prior to the failure, the anaerobic digester struggled with poor and inconsistent biogas production for almost 10 months. The operators conducted routine testing during this period and adjusted the feedstock blend. It seemed like the digester was improving and the biogas production increasing for about three months. Then, the digester failed again. That is when the operators called Azura Associates for assistance.
Azura uses a two-tiered anaerobic digester optimization process to improve biogas production performance. In this specific case, detailed testing revealed problematic concentrations of long-chain fatty acids (LCFAs) and volatile fatty acids (VFAs). These inhibitory compounds resulted in the digester failure. Following a strong intervention campaign, backed by frequent sampling and laboratory testing, the biogas production was restored to the 80% level within 2 months. Full name-plate capacity was achieved a few weeks after that.
This case study highlighted the importance of integrating regular monitoring to maintain or reach optimal anaerobic digester performance. This information, along with other valuable content delivered in Dr. Hecht’s lecture, are crucial for ensuring successful anaerobic digester projects. Their continued widespread adoption plays a key role in creating a sustainable future.
Further information on the IBBK can be found here: https://ibbk-biogas.com/