| 11. |
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| 12. |
- Björnsson, Lovisa, et al.
(författare)
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Introduction of grass-clover crops as biogas feedstock in cereal-dominated crop rotations. Part II: Effects on greenhouse gas emissions
- 2014
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Ingår i: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector. - 9780988214576 ; , s. 134-141
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Konferensbidrag (refereegranskat)abstract
- In an analysis of climate effects, increased soil organic carbon will have a dual effect due to both increased soil fertility and carbon sequestration. Even so, soil carbon changes are neglected in many crop production LCAs. In the present study, the introduction of grass-clover crops in cereal-dominated crop production was evaluated. The grass-clover crops were used for biogas production, and the digested residue was recycled to the farm as biofertilizer. A shift from the cereal-dominated crop rotation to integrated production of food crops and one or two years of grass-clover crops used as biogas feedstock would result in avoided emissions of 2-3 t CO2-eq. ha-1 a-1. Integrated food and energy crop production would in this case improve soil organic carbon content at the same time as resulting in considerably decreased greenhouse gas emissions from the cultivation system.
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| 13. |
- Björnsson, Lovisa
(creator_code:cre_t)
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Pretreating non-wood lignocellulosic material (e.g. bagasse) to produce ethanol, comprises adding organic acid or organic acid-producing bacteria to lignocellulosic material, and storing and heating the organic acid-impregnated material
- 2012
-
Patent (övrigt vetenskapligt/konstnärligt)abstract
- NOVELTY - Pretreating non-wood lignocellulosic material containing less than 5 wt.% starch or sugar for producing ethanol from lignocellulose, comprises: (a) adding organic acid or organic acid-producing bacteria to the lignocellulosic material; (b) storing the lignocellulosic material in presence of organic acid for at least 2 weeks in an atmosphere of less than 5% oxygen to obtain organic acid-impregnated material; and (c) heating the organic acid-impregnated material at a temperature of at least 190 degrees C for at least 5 minutes to obtain pretreated lignocellulosic material. USE - The method is useful for pretreating non-wood lignocellulosic material to produce ethanol, where the non-wood lignocellulosic material is bagasse (preferably sugar cane bagasse or sweet Sorghum bagasse), sugar cane trash, wheat straw, rice straw, Sorghum species, Arundo, Miscanthus or agricultural residues (all claimed). ADVANTAGE - The method: avoids the need of inorganic acid or base (sulfur dioxide), and utilizes containers which are less corrosion resistant, hence economical; has higher net energy gain; utilizes organic acid which is biodegradable, and produces degradation products (e.g. 5-hydroxymethylfurfural and furfural which acts as inhibitory substances in the subsequent fermentation process), thus environmentally friendly. DETAILED DESCRIPTION - Pretreating non-wood lignocellulosic material containing less than 5 wt.% starch or sugar for producing ethanol from lignocellulose, comprises: (a) adding organic acid or organic acid-producing bacteria to the lignocellulosic material; (b) storing the lignocellulosic material in the presence of organic acid for at least 2 weeks in an atmosphere of less than 5% oxygen to obtain organic acid-impregnated material; and (c) heating the organic acid-impregnated material at a temperature of at least 190 degrees C for a period of at least 5 minutes to obtain pretreated lignocellulosic material, where no inorganic acid or base including sulfur dioxide is added in the method.
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| 14. |
- Bohn, Irene, et al.
(författare)
-
Torrötning av rejekt från förbehandling av matavfall.
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- När källsorterat matavfall från hushållen rötas i en biogasanläggning av modellen omrörd tank behövs en förbehandling för att göra materialet pumpbart och ta bort orenheter. En typ av förbehandling innebär att avfallet passerar genom en skruvpress som delar avfallet i en pumpbar fraktion och en torr fraktion, så kallat rejekt. På NSR förbehandlas matavfallet med denna teknik och rejektet skickas idag till förbränning. Tidigare studier har visat att ca 30% av metanpotentialen i matavfallet finns kvar i rejektet. Syftet med detta projekt var att undersöka möjligheterna att utvinna den kvarvarande metanpotentialen genom att testa satsvis torrötning med efterföljande kompostering som alternativ till förbränning. Vid satsvis torrötning i lakbädd läggs materialet i en reaktor (lakbädd) som översilas med vätska. Det är därför viktigt att lakbädden har en porös struktur som gör att vätskan fördelas jämt i materialet. Rötning av enbart rejekt och rejekt blandat med strukturmaterial testades för att undersöka om inblandning av strukturmaterial gav någon effekt. För att undersöka flödesegenskaperna i lakbädd, med och utan inblandning av strukturmaterial, genomfördes två spårämnesförsök. Efter rötningen komposterades den fasta rötresten, och färdiga kompostens kvalitet utvärderades. Porlukten i rötresten och i komposten under komposteringsprocessen och efter siktning av komposten utvärderades dessutom. Spårämnesförsöken och rötningsförsöken visade att inblandning av strukturmaterial påverkade flödesmönstret och rötningsprocessen i lakbädden i positiv riktning. Tillsats av strukturmaterial var nödvändigt för att rötningsprocessen skulle fungera. Tekniken med spårämnesförsök visade sig vara lämplig för att indikera graden av homogen perkolering av bädden. Vid rötning av rejekt uppblandat med strukturmaterial uppnåddes ett metanutbyte på 100 Nm3 metan per ton blandning vilket motsvaradedet förväntade metanutbytet. Vid kompostering av materialet uppnåddes kraven på hygienisering och halt av tungmetaller. Däremot var halten synliga orenheter över 2 mm för hög, och den siktning med 15 mm såll som genomfördes visade sig inte vara tillräcklig som efterbehandling av komposten. Luktpotentialen i den siktade komposten var runt 300 OUE/m3 vilket kan beskrivas som oproblematisk, medan luktpotentialen i rötresten och under komposteringsprocessen var högre.
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| 15. |
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| 16. |
- Gissén, Charlott, et al.
(författare)
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Comparing energy crops for biogas production Yields, energy input and costs in cultivation using digestate and mineral fertilisation
- 2014
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Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 64, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- Analyses of six crops grown in southern Sweden for biogas production (hemp, sugar beet, maize, triticale, grass/clover ley, winter wheat) showed varying performance regarding methane yield per hectare and energy input and costs in the production and supply of crops as biogas feedstock. The highest biomass and biogas yield was observed for sugar beet. Crops with lower risk of negative environmental impact in cultivation, such as ley and hemp, produced less than half the methane energy yield per hectare. Triticale, also having less risk of negative environmental impact, gave an energy yield similar to that of winter wheat grain and maize. Replacing most of the mineral fertiliser with biogas digestate did not, with the exception for hemp, influence crop yields per hectare, but energy input in cultivation decreased by on average 34% for the six crops tested. For hemp and sugar beet the biogas feedstock costs for the freshly harvested crop per GJ methane were close to that of the economic reference crop, winter wheat grain. For maize, beet tops and first and second year ley, the feedstock costs were lower, and for triticale much lower. When ensiled crops were used for biogas the feedstock costs increased and only those of triticale silage remained slightly lower than the cost of dried wheat grain. However, all feedstock costs were so high that profitable biogas production based solely on ensiled crops would be difficult to achieve at present Swedish biogas sales prices. (c) 2014 Elsevier Ltd. All rights reserved.
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| 17. |
- Ivo Achu, Nges, et al.
(författare)
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Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production.
- 2012
-
Ingår i: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 32:1, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester.
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| 18. |
- Ivo Achu, Nges, et al.
(författare)
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High methane yields and stable operation during anaerobic digestion of nutrient-supplemented energy crop mixtures
- 2012
-
Ingår i: Biomass & Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 47, s. 62-70
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of digesting energy crops supplemented with macro- and micronutrients instead of manure, without the commonly applied long hydraulic retention time (HRT), was investigated in long-term, single-stage continuous stirred tank processes. The crops used were mixtures of sugar beets, maize and whole crop triticale. The organic loading rate (OLR) measured as a total solid (TS) was 1.5-5.5 kg m(-3) d(-1) and the HRT from 30 to 40 days. The results showed high methane yields, comparable to those in batch digestion, and high stability. The digestion of beets only was most stable, and showed the highest average TS-based methane yield (383 +/- 26 m(3) kg(-1)) at an OLR of 4.5 kg m(-3) d(-1) and a HRT of 40 days. No significant difference in methane yield was found for all the crop mixtures during stable operation. Nutrient addition therefore showed the same stimulatory and stabilising effects as manure with high methane yields achieved at relatively short HRTs. (c) 2012 Elsevier Ltd. All rights reserved.
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| 19. |
- Ivo Achu, Nges, et al.
(författare)
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Improved utilization of fish waste by anaerobic digestion following omega-3 fatty acids extraction.
- 2012
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797. ; 110, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- Fish waste is a potentially valuable resource from which high-value products can be obtained. Anaerobic digestion of the original fish waste and the fish sludge remaining after enzymatic pre-treatment to extract fish oil and fish protein hydrolysate was evaluated regarding the potential for methane production. The results showed high biodegradability of both fish sludge and fish waste, giving specific methane yields of 742 and 828 m(3)CH(4)/tons VS added, respectively. However, chemical analysis showed high concentrations of light metals which, together with high fat and protein contents, could be inhibitory to methanogenic bacteria. The feasibility of co-digesting the fish sludge with a carbohydrate-rich residue from crop production was thus investigated, and a full-scale process outlined for converting odorous fish waste to useful products.
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| 20. |
- Ivo Achu, Nges, et al.
(författare)
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Stable operation during pilot-scale anaerobic digestion of nutrient-supplemented maize/sugar beet silage
- 2012
-
Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 118, s. 445-454
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Tidskriftsartikel (refereegranskat)abstract
- Biogas production from maize/sugar beet silage was studied under mesophilic conditions in a continuous stirred tank reactor pilot-scale process. While energy crop mono-digestion is often performed with very long hydraulic retention times (HRTs), the present study demonstrated an efficient process operating with a 50-day HRT and a corrected total solids (TScorr) based organic loading rate of 3.4 kg/m3×d. The good performance was attributed to supplementation with both macro- and micronutrients and was evidenced by good methane yields (318 m3/ton TScorr) which were comparable to laboratory maximum expected yields plus low total volatile fatty acid concentrations (< 0.8 g/L). A viscoplastic and thixotropic digester fluid behaviour was observed, and the viscosity problems common in crop mono-digestion were not seen in this study. The effluent also complied with Swedish certification standards for bio-fertilizer for farmland application. Nutrient addition thus rendered a stable biogas process, while the effluent was a good quality bio-fertilizer.
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