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Improving the fertiliser value of digestates from biogas plants

During his PhD studies, Jared Nyang'au researched how the anaerobic digestion process could be optimised to enhance the fertiliser value of digestates. The increasing utilisation of high dry matter lignocellulosic biomass as co-substrates in anaerobic digestion, due to their economic viability, to increase biogas production presents a significant challenge.

Photo: Jared Onyango Nyang'au

It results in digestates with high dry matter concentrations, causing high ammonia emissions after surface application and low nitrogen fertilising effects. Jared  explored how biomass pre-treatment techniques, biogas operation parameters and digestates’ post-treatment influence nutrient availability and fertilising properties of the digestates from biogas plants.
The new research findings contribute to the understanding of how digestate quality and fertiliser value could be improved by integrating appropriate biomass pre-treatment and digestate post-treatment technologies into biogas plants.

The PhD study was completed at the Department of Agroecology, Faculty of Technical Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Friday, 8th March 2024 at 10:00
Place: 8814-3075, AU Viborg - Auditorium, Department of Agroecology, Aarhus University, Blichers Allé 20, 8830 Tjele
Title of PhD thesis: Designing pre-treatment and anaerobic digestion of biowastes for higher crop nutrient utilisation
Contact information: Jared Onyango Nyang'au, e-mail: jn@agro.au.dk, tel.: +45 91115562

Members of the assessment committee:
Professor Dr. Klaus Dittert, Department of Crop Sciences, Division Plant Nutrition and Crop Physiology, Georg-August-University Göttingen, Germany

Senior Researcher Dr. Andreas S. Pacholski, Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany

Senior Researcher, Jim Rasmussen (chair), Department of Agroecology, Aarhus University, Denmark

Main supervisor:
Professor Peter Sørensen, Department of Agroecology, Aarhus University, Denmark

Senior Researcher Henrik Bjarne Møller, Department of Biological and Chemical Engineering, Aarhus University, Denmark

Language: The PhD dissertation will be defended in English
The defence is public.
The PhD thesis is available for reading at the Graduate School of Technical Sciences/GSTS,

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