Forschungsseminar: Vortrag von Dr. Sabrina Dumfort

Improving Biomass Storability through pH-Altering Additives - Dr. Sabrina Dumfort

The storage of solid biomass is a critical but often underestimated element in ensuring reliable feedstock availability for bioenergy systems. In particular, wood chips are prone to substantial dry matter losses during storage due to intense microbial activity, with annual losses reaching up to 40%. These biological degradation processes not only diminish the energetic value of the material but also pose health risks, as many naturally occurring microorganisms in fresh wood chips include potentially harmful species. Although technical drying is currently the only widely applied mitigation strategy, it is energy-intensive and economically impractical for low-quality biomass such as forest residues.

During this talk, the key findings of the dissertation entitled “Improvement of the storability of wood chips through the application of pH altering additives” will be presented, which introduces an alternative preservation strategy based on the use of alkaline additives. By shifting the pH of fresh biomass from an acidic to an alkaline environment, microbial growth can be effectively suppressed. Laboratory screenings identified calcium hydroxide (Ca(OH)₂) as a particularly suitable additive. Building on these results, four-month industrial-scale storage trials with spruce and poplar wood chips were conducted. Throughout the experiments, temperature, moisture, pH dynamics, gas emissions and dry matter losses were monitored. These measurements were complemented by molecular analyses of bacterial and fungal communities (qPCR, Illumina MiSeq sequencing) and enzyme activity assays. Additional combustion and gasification tests in pilot and industrial facilities evaluated the implications of additive use for the further conversion to energy.

Yet, storage-related issues are not limited to wood chips. Similar challenges arise in other biomass streams, such as sewage sludge. In this case uncontrolled self-heating and mold formation are common, leading to significant handling, safety and stability issues. In an ongoing field experiment, the storage behavior of sewage sludge treated with Ca(OH)₂ is being monitored with a focus on pile temperature dynamics and mold development. Preliminary findings together with the experimental design will be presented.

Um die Forschungsseminare für alle angenehm zu gestalten, bitten wir Sie herzlich Folgendes zu beachten:

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Vielen Dank für Ihr Mitwirken.

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