Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2023
Abstract
No abstract has been registered
Authors
Yi Zhang Yijing Feng Zhonghao Ren Runguo Zuo Tianhui Zhang Yeqing Li Yajing Wang Zhiyang Liu Ziyan Sun Yongming Han Lu Feng Mortaza Aghbashlo Meisam Tabatabaei Junting PanAbstract
The ideal conditions for anaerobic digestion experiments with biochar addition are challenging to thoroughly study due to different experimental purposes. Therefore, three tree-based machine learning models were developed to depict the intricate connection between biochar properties and anaerobic digestion. For the methane yield and maximum methane production rate, the gradient boosting decision tree produced R2 values of 0.84 and 0.69, respectively. According to feature analysis, digestion time and particle size had a substantial impact on the methane yield and production rate, respectively. When particle sizes were in the range of 0.3–0.5 mm and the specific surface area was approximately 290 m2/g, corresponding to a range of O content (>31%) and biochar addition (>20 g/L), the maximum promotion of methane yield and maximum methane production rate were attained. Therefore, this study presents new insights into the effects of biochar on anaerobic digestion through tree-based machine learning.
Authors
Yi Zhang Zhangmu Jing Yijing Feng Shuo Chen Yeqing Li Yongming Han Lu Feng Junting Pan Mahmoud Mazarji Hongjun Zhou Xiaonan Wang Chunming XuAbstract
Exploring key factors has important guidance for understanding complex anaerobic digestion (AD) systems. This study proposed a multi-layer automated machine learning framework to understand the complex interactions in AD systems and explore key factors at the environmental factor, microorganisms and system levels. The first layer of the framework identified hydraulic residence time (HRT) as the most important environmental factor, with an optimal range of 33–45 d. In the second layer of the framework, Methanocelleus (optimal relative abundance (ORA) = 3.0%) and Candidatus_Caldatribacterium (ORA = 1.7%) were found to be the key archaea and bacteria, respectively. Furthermore, the prediction of key microorganisms based on environmental factors and remaining microbial data showed the essential roles of Methanothermobacter and Acetomicrobium. The third layer for finding the optimal combination of data variables for predicting biogas production demonstrated that combined Archaea genera and environmental factors should be achieved for the most accurate prediction (root mean square error (RMSE) = 84.21). GBM had the best model performance and prediction accuracy among all the built-in models. Based on the optimal GBM model, the analysis at the system level showed that HRT was the most important variable. However the most important microorganism, Methanocelleus, within the appropriate survival range is also essential to achieve optimal biogas production. This research explores key parameters at various levels through automated machine learning techniques, which are expected to provide guidance in understanding the complex architecture of industrial and laboratory AD systems.
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
Tire wear particles (TWP) are a major source of microplastics that are mainly transported by stormwater from roads to the environment. Their risk has not yet been sufficiently evaluated, mainly because of the lack of suitable analytical methods for identifying and measuring their environmental concentrations. Moreover, TWP are persistent in the environment while their generation is increasing, which calls for action to limit their environmental spread. Conversely, stormwater management solutions are becoming a growing fixture in the road environment for their multipurpose role in controlling peak runoff and reducing pollution. However, knowledge of the effect of stormwater management solutions in removing TWP is limited. The overall goal of this Ph.D. study was to introduce a suitable analytical method for detecting and quantifying TWP in the environment and measuring the actual concentrations of TWP in sediments of stormwater management solutions associated with roads. Three study sites and laboratory experiments were used as data sources for the studies included in this thesis (Papers I–IV). Simultaneous thermal analysis (STA) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the samples, and parallel factor analysis (PARAFAC) was used for data analysis. Analysis of variance (ANOVA) and t-tests were used for statistical analysis.
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Márk Rékási Péter Ragályi Déniel Benjámin Sándor Anita Szabó Pierre-Adrien Rivier Csilla Farkas Orsolya Szécsy Nikolett UzingerAbstract
Vermicomposts and composts prepared from sewage sludge digestate and additives (spent mushroom compost, straw, biochar) after 43 days pre-composting followed by 90 days vermicomposting with Eisenia fetida or by compost maturing were investigated regarding the potentially toxic element (PTE) As, Co, Cr, Cu, Mo, Ni, Pb and Zn contents. The average increment in the total PTE concentration for the entire process was ten times higher (104 %) compared to the increment solely in the composting or vermicomposting (9.3 and 9.5 %, respectively) after pretreatment. Compared to the untreated digestate the As and Co concentrations in the final mixtures were 26 and 51 % higher, respectively while for the other PTEs 26 ± 9 % average decrease was observed. Total PTE content was the same in composts and vermicomposts. Average PTE bioavailability (water soluble/total concentration) was statistically the same in vermicomposts (2.5) and composts (2.7), but lower in mixtures with biochar (2.5) than without it (2.8).
Authors
Miguel Las Heras Hernandez Francis Isidore Barre Nils Maximilian Dittrich Avijit Vinayak Pandit Anne Falk Øgaard Daniel B. MüllerAbstract
No abstract has been registered
Authors
Daniel Beat Müller Miguel Las Heras Hernandez Avijit Vinayak Pandit Anne Falk Øgaard Kjell Inge ReitanAbstract
Phosphorus is a building block for all life and therefore plays an essential role in food production. Currently, large amounts of phosphorus enter the Norwegian food system from abroad in the form of mineral fertilizer, feedstuff, food, as well as micro-ingredients for animal feed, mainly in salmon farming. However, only a small fraction of this phosphorus ends up as food for humans, while the largest part accumulates in soil and water systems. This inefficiency entails two challenges: 1. Phosphorus supply is critical. Phosphate rock, the primary source of phosphorus for fertilizer and micro-ingredient production, is a limited resource that is highly concentrated in a few countries. Over 80% of global phosphate rock reserves are found in only 5 countries, and ~70% are located in Morocco and Morocco-occupied Western Sahara. The high concentration renders many countries vulnerable to geopolitical and economic instabilities and threatens food safety. The EU has therefore included phosphate rock on its list of Critical Raw Materials. 2. The accumulation of phosphorus in water systems can lead to eutrophication and dead zones, threatening fish stocks and other aquatic life. The high phosphorus concentration in soils due to overfertilization over long periods of time increases the danger of losses to water systems by runoff, further exacerbating the eutrophication risk. A more circular use of phosphorus could simultaneously reduce supply and pollution risks. This is particularly relevant in Norway, where the government has an ambition to increase salmon and trout production from currently 1,5 to 5 million tons by 2050. Achieving a circular phosphorus economy is a complex task: (i) The land- and the sea-based food systems are increasingly interlinked, for example through agricultural production of fish feed or the application of fish sludge on agricultural land. (ii) The Norwegian phosphorus cycle is increasingly interlinked with that of other countries as trade flows along the entire food supply chain are growing. (iii) Phosphorus fertilizers, both primary and recycled, are often contaminated with heavy metals such as cadmium, uranium, and zinc, which tend to accumulate in soils. Cleaning the phosphorus cycle is therefore vital for soil fertility and human health. This report is based on the MIND-P project, which studied the Norwegian phosphorus cycle for both agriculture and aquaculture at a farm-by-farm basis and explored options for increasing circularity. The project identified farm-level and structural barriers to managing phosphorus resources more effectively. We propose four fundamental strategies to overcome these barriers: 1. Develop and maintain a national nutrient accounting. 2. Minimize phosphorus losses and accumulations at farm level. 3. Establish infrastructures for capturing, processing, trade, and use of manure and fish sludge to produce high-quality recycled fertilizers that are tailored to the needs of the users in Norway and abroad. 4. Adopt a regulatory framework to promote a market for recycled fertilizer. The strategies proposed here were developed with the support of an Advisory Panel consisting of representatives from government, industry, industry associations, and NGOs in an online and two physical workshops conducted in 2022.
Abstract
The aim of this study was to contribute to development of organic fertiliser products based on fish sludge (i.e. feed residues and faeces) from farmed smolt. Four dried fish sludge products, one liquid digestate after anaerobic digestion and one dried digestate were collected at Norwegian smolt hatcheries in 2019 and 2020. Their quality as fertilisers was studied by chemical analyses, two 2-year field experiments with spring cereals and soil incubation combined with a first-order kinetics N release model. Cadmium (Cd) and zinc (Zn) concentrations were below European Union maximum limits for organic fertilisers in all products except one (liquid digestate). Relevant organic pollutants (PCB7, PBDE7, PCDD/F + DL-PCB) were analysed for the first time and detected in all fish sludge products. Nutrient composition was unbalanced, with low nitrogen/phosphorus (N/P) ratio and low potassium (K) content relative to crop requirements. Nitrogen concentration in the dried fish sludge products varied (27–70 g N kg-1 dry matter), even when treated by the same technology but sampled at different locations and/or times. In the dried fish sludge products, N was mainly present as recalcitrant organic N, resulting in lower grain yield than with mineral N fertiliser. Digestate showed equally good N fertilisation effect as mineral N fertiliser, but drying reduced N quality. Soil incubation in combination with modelling is a relatively cheap tool that can give a good indication of N quality in fish sludge products with unknown fertilisation effects. Carbon/N ratio in dried fish sludge can also be used as an indicator of N quality.