Linn Solli
Research Scientist
Biography
Education: Doctoral degree (PhD) (2017) in microbiology at the University of Life Sciences, NMBU.
Area of research:
- Blue / green bio economy (agriculture / aquaculture)
- Climate and environmentally friendly management of organic residual fractions (animal manure, fish sludge, slaughterhouse waste etc)
- Anaerobic degradation of organic fractions
- Biogas process and methane production
- Dynamics in anaerobic microbiological communities
- Tolerance for nitrogen (ammonia) and fatty acids (LCFA / VFA) in anaerobic microbiological communities
- Syntrophic relations between different groups of bacteria and methanogenic Archaea
At Ås we have Norway's largest biogas laboratory, with equipment and instruments for various types of biogas experiments (e.g. potential tests, long-term continuous biogas experiments, analysis of gas and organic material). The laboratory also has facilities for micro-algae experiments, composting experiments and a number of different analyzes.
Abstract
Food waste collection in Norway is mostly done using plastic bags, made either of polyethylene or, more recently, of biodegradable plastics, which are materials that can be degraded by microorganisms under certain environmental conditions and time frames. Most of the biodegradable plastic bags used in Norway for food waste collection are labelled as compostable, i.e. degradable under composting conditions, but end up in biogas plants and only rarely in composting plants. The present work provides answers to the following questions. First, to what extent are biodegradable plastic bags deteriorated during anaerobic digestion of food waste. Secondly, is the situation different under mesophilic (37°C) and thermophilic (55°C) conditions. Finally, does thermal hydrolysis (THP) pretreatment of food waste containing biodegradable plastic change the results. In tests offering optimal conditions for microorganisms involved in anaerobic digestion, limited deterioration of biodegradable plastics (Mater-Bi® certified as compostable under industrial (ICP) and home (HCP) composting conditions, representative of what is used in Norway for food waste collection for biogas production) was observed, as shown by limited mass loss (14-21 % for ICP and 22-33 % for HCP) and limited changes in the chemical composition after 22 d, a relevant hydraulic retention time for industrial biogas plant operations. Higher mass loss was observed under thermophilic conditions compared to mesophilic conditions. The effect of THP pretreatment of food waste containing biodegradable plastics offered unexpected results: while a small, non-significant increase in mass loss was observed for ICP, THP led to a significantly reduced mass loss for HCP during anaerobic digestion. The biogas process itself was not significantly affected by ICP and HCP present in food waste at a 4 % plastic to food waste ratio. The present research shows that the majority (79-86 % of ICP and 67-78 % of HCP) of biodegradable plastic residues left after initial pretreatment of food waste, will withstand anaerobic conditions, both under mesophilic and thermophilic conditions, also when subjected to THP pretreatment (5 bars, 160°C, 20 min). This strongly suggests that post-treatment of digestate is required to avoid the spread of biodegradable plastics to agricultural soils, for digestates intended for agricultural use.
Authors
Getachew Birhanu Abera Erik Trømborg Linn Solli Juline M Walter Radziah Wahid Espen Govasmark Svein Jarle Horn Nabin Aryal Lu FengAbstract
Biofilm is a syntrophic community of microorganisms enveloped by extracellular polymeric substances and displays remarkable adaptability to dynamic environments. Implementing biofilm in anaerobic digestion has been widely investigated and applied as it promotes microbial retention time and enhances the efficiency. Previous studies on anaerobic biofilm primarily focused on application in wastewater treatment, while its role has been significantly extended to accelerate the degradation of lignocellulosic biomass, improve gas–liquid mass transfer for biogas upgrading, or enhance resistance to inhibitors or toxic pollutants. This work comprehensively reviewed the current applications of biofilm in anaerobic digestion and focused on impacting factors, optimization strategies, reactor set-up, and microbial communities. Moreover, a full-scale biofilm reactor case from Norway is also reported. This review provides a state of-the- art insight on the role of biofilm in anaerobic digestion.
Authors
Getachew Birhanu Abera Aryan Bhusal Nabin Aryal Thea Os Andersen Linn Solli Svein Jarle Horn Lu Feng Begum BilgicAbstract
No abstract has been registered