| 1. |
- Anukam, Anthony, et al.
(författare)
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A Review of the Chemistry of Anaerobic Digestion : Methods of Accelerating and Optimizing Process Efficiency
- 2019
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Ingår i: Processes. - Basel : MDPI. - 2227-9717. ; 7:8, s. 1-19
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Forskningsöversikt (refereegranskat)abstract
- The anaerobic digestion technology has been in existence for centuries and its underlying theory established for decades. It is considered a useful technology for the generation of renewable energy, and provides means to alleviate problems associated with low access to energy. However, a great deal of current research is targeted towards the optimization of this technology under diverse digestion process conditions. This review presents an in-depth analysis of the chemistry of anaerobic digestion and discusses how process chemistry can be used to optimize system performance through identification of methods that can accelerate syntrophic interactions of different microorganisms for improved methanogenic reactions. Recent advances in addition to old research are discussed in order to offer a general but comprehensive synopsis of accumulated knowledge in the theory of anaerobic digestion, as well as an overview of previous research and future directions and opportunities of the AD technology. Achieving a sustainable energy system requires comprehensive reforms in not just economic, social and policy aspects, but also in all technical aspects, which represents one of the most crucial future investments for anaerobic digestion systems.
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| 2. |
- Berghel, Jonas, 1966-, et al.
(författare)
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From sawdust to pellets. Still a challenge...
- 2012
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Ingår i: Public Service Review European Union. - : European union. ; :33, s. 398-399
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Berghel, Jonas, 1966-, et al.
(författare)
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Lösningarna finns! Är pelletsproducenterna medvetna om problemen?
- 2011
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Ingår i: Bioenergi. - Gävle : Region Gävleborg. - 9789163391262 ; , s. 25-29
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Sverige är inte längre världsledande som pelletsproducent. USA producerar allra mest pellets i världen. Kanada och Ryssland producerar också allt mer pellets. Ingen av dessa länder har någon omfattande inhemsk konsumtion. I stort sett all pellets exporteras och det sker huvudsakligen till Europa. Sannolikt kommer det att leda till att priset på pellets i Europa sjunker, med följd att lönsamheten för svenska pelletsproducenter minskar.
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| 5. |
- Berghel, Jonas, 1966-, et al.
(författare)
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The effects of kraft lignin additives on wood fuel pellet quality, energy use and shelf life
- 2013
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 112:0, s. 64-69
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Tidskriftsartikel (refereegranskat)abstract
- In 2011, the total consumption of pellets in Sweden amounted to 1.9 million tons, which represents an energy value of 9 TWh. The pellets are used in large-scale as well as in small-scale applications, and increased demands on pellet quality are likely to force pellet producers to improve on the pellet properties. One way of increasing pellet quality is by using additives. The purpose of this article, therefore, is to examine kraft lignin as an additive. Pelletswere produced in a small industrial pellet press located at KarlstadUniversity, Karlstad, Sweden, and 1–4% of kraft lignin was added to the pellets. The results indicate that the addition of an increased amount of kraft lignin to the pellets increases their mechanical durability and their lengths. The results also indicate that dry kraft lignin yields pellets with higher durability as compared to wet kraft lignin. The energy demand was unaffected by the increased use of kraft lignin. The general results presented in this paper are useful for producers of lignin, pellet producers and end-users of pellets, who are interested in developing their products and/or improving the production processes.
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| 6. |
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| 7. |
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| 8. |
- Eskandari, Samieh, et al.
(författare)
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Hydrochar-Amended Substrates for Production of Containerized Pine Tree Seedlings under Different Fertilization Regimes
- 2019
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Ingår i: Agronomy. - : MDPI. - 2073-4395. ; 9:7, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing body of research that recognizes the potentials of biochar application in agricultural production systems. However, little is known about the effects of biochar, especially hydrochar, on production of containerized seedlings under nursery conditions. This study aimed to test the effects of hydrochar application on growth, quality, nutrient and heavy metal contents, and mycorrhizal association of containerized pine seedlings. The hydrochar used in this study was produced through hydrothermal carbonization of paper mill biosludge at 200 °C. Two forms of hydrochar (powder and pellet) were mixed with peat at ratios of 10% and 20% (v/v) under three levels of applied commercial fertilizer (nil, half and full rates). Application of hydrochar had positive or neutral effects on shoot biomass and stem diameter compared with control seedlings (without hydrochar) under tested fertilizer levels. Analysis of the natural logarithmic response ratios (LnRR) of quality index and nutrient and heavy metal uptake revealed that application of 20% (v/v) hydrochar powder or pellet with 50% fertilizer resulted in same quality pine seedlings with similar heavy metal (Cu, Ni, Pb, Zn and Cr) and nutrient (P, K, Ca and Mg) contents as untreated seedlings supplied with 100% fertilizer. Colonization percentage by ectomycorrhizae significantly increased when either forms of hydrochar were applied at a rate of 20% under unfertilized condition. The results of this study implied that application of proper rates of hydrochar from biosludge with adjusted levels of liquid fertilizer may reduce fertilizer requirements in pine nurseries.
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| 9. |
- Forslund Frykedal, Karin, 1961-
(författare)
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Elevers tillvägagångssätt vid grupparbete : Om ambitionsnivå och interaktionsmönster i samarbetssituationer
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the dissertation is to add to our knowledge and understanding of how groupwork and group tasks are construed among students. This is accomplished be creating a model, which describes the pattern of interaction and the experience that emerge as students try to handle the group-work situation. An additional aim is to use the outcomes of the study as a basis for discussions about how to carry out group-work in the classroom. The methodological point of departure is grounded theory and the theoretical perspective is symbolic interaktionism. A theoretical model - Students’ creation of trust in group-work - has been constructed from observations and interviews in grade 7 and 8 from a local school. The model describes what happens when students with different social and academic ambitions meet in a group assignment and become interdependent. The students have to consider their own and others’ ambitions, the composition of the group, as well as the task, and they have different possibilities to influence these factors. Easiest to influence are the construction of the task and the group composition, which they also try to do so as to diminish the differences in ambitions and the interdependency. They do not always succeed and they handle the remaining differences in ambitions and dependency through creation of trust, by constructing different behaviours during the group-work. The insights derived from the theoretical model - Students’ creation of trust in groupwork - could have practical implications when group-work is applied. This means that teacher could assist the students in their efforts to create trust among group members. This study has pointed out construction of the task, clear goals, and group composition as import pre- requisites for the use of group-work as a means of instruction. The dissertation ends with a discussion about teachers’ possibilities to contribute to collaboration in group-work through the construction of tasks, composition of the groups and to the construction of goals which creates situations of trust in group-work.
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| 10. |
- Frodeson, Stefan, Universitetsadjunkt, 1968-, et al.
(författare)
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The Potential for a Pellet Plant to Become a Biorefinery
- 2019
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Ingår i: Processes. - Basel : MDPI. - 2227-9717. ; 7:4, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery.
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