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Sökning: WFRF:(Björnsson Lovisa)

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61.
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62.
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63.
  • Lantz, Mikael, et al. (författare)
  • Styrmedel för en ökad produktion av gödselbaserad biogas - En fallstudie för Skåne och Västra Götalands län
  • 2014
  • Rapport (övrigt vetenskapligt)abstract
    • Produktion av biogas från gödsel har i flera studier visat sig leda till stora positiva miljöeffekter, i synnerhet vad gäller emissioner av växthusgaser, jämfört med andra förnybara energibärare. Skälet är att produktionen av biogas, utöver att ersätta fossila bränslen, också ger en minskad miljöpåverkan från konventionell hantering av stallgödsel. Trots dessa positiva miljöeffekter utnyttjas dock endast ett par procent av biogaspotentialen från gödsel, som i Sverige uppgår till cirka 3 TWh per år. Skåne och Västra Götaland är de två län som har störst potential och syftet med föreliggande studie har bland annat varit att på regional nivå beräkna miljönyttan och det samhällsekonomiska värdet av att producera biogas från gödsel samt att beskriva nuvarande och planerad produktion. Syftet har också varit att analysera behovet av ytterligare ekonomiska incitament och huruvida sådana styrmedel skulle kunna införas på regional nivå. År 2012 producerades endast cirka 10 GWh gödselbaserad biogas i de två länen. Baserat på den sammanställning som genomförts här kan det dock konstateras att produktionen kan komma att öka betydligt de närmaste åren om alla planerade projekt genomförs. Sett till den totala potentialen är det trots detta inte mer än drygt 20 % respektive 10 % av potentialen som skulle utnyttjas i Skåne respektive Västra Götaland. Samtidigt menar flera aktörer att de ekonomiska förutsättningarna är mycket begränsade och en stor del av projekten har ännu inte fattat några investeringsbeslut. I de intervjuer som genomförts har regionala och nationella branschaktörer bland annat fått svara på om de ser ett behov av ytterligare styrmedel för att främja en gödselbaserad produktion av biogas och vilken typ av styrmedel de i sådana fall skulle föredra utifrån sin situation. Med något undantag menar samtliga aktörer att man föredrar ett produktionsstöd framför ett investeringsstöd. Merparten av de större bolagen ser dock gärna stöd i form av ett klimatcertifikat som också gynnar andra substrat utöver gödsel. De lantbruksanknutna aktörerna för istället fram det så kallade metanreduceringsstödet som tidigare föreslagits av Energimyndigheten och är kopplat endast till biogasproduktion från gödsel. Utöver önskemålen om direkta stöd är det också flera aktörer som nämner ett fortsatt behov av satsning på infrastruktur och de offentliga aktörernas betydelse som användare av i första hand fordonsgas. Baserat på dessa intervjuer och de litteraturstudier som genomförts presenteras ett antal olika styrmedel som direkt eller indirekt skulle kunna förbättra förutsättningarna för en ökad gödselbaserad produktion av biogas. När arbetet med denna studie inleddes fanns det inte några förslag på nationella styrmedel för att främja en gödselbaserad produktion av fordonsgas. I september 2013 kom dock besked om att regeringen avsätter medel till ett sådant stöd i form av ett pilotprojekt på 10 år. Som en del i denna studie inkluderades därför en beräkning av hur olika avgränsningar i detta stöd skulle kunna påverka produktionen i respektive region. Avgränsningar som analyserats är bland annat krav på hur biogasen ska användas och krav på andelen gödsel i biogasanläggningen. Resultatet visar att merparten av biogasproduktionen, så som projekten är utformade nu, kommer att ske i anläggningar som tar emot minst 80 % gödsel och som producerar fordonsgas. Sådana avgränsningar kommer därmed att ha relativt liten betydelse för kostnader och utfall förknippade med stödsystemet. Däremot kan det ha stor betydelse för enskilda anläggningar. Förutsättningarna för att införa nya styrmedel på regional nivå tycks vara något mer begränsade. De alternativ som ligger närmast tillhands bedöms därför vara satsningar som gynnar biogasutvecklingen i stort, utan att offentliga medel riktas mot en enskild aktör, samt att ställa krav som gynnar gödselbaserad biogas i den regionala upphandlingen av varor och tjänster.
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64.
  • Lantz, Mikael, et al. (författare)
  • The prospects for an expansion of biogas systems in Sweden - Incentives, barriers and potentials
  • 2007
  • Ingår i: Energy Policy. - : Elsevier. - 1873-6777. ; 35:3, s. 1830-1843
  • Forskningsöversikt (refereegranskat)abstract
    • Biogas is a renewable, high-quality fuel, currently produced at more than 200 locations in Sweden. The present production is some 5 PJ/year but the potential is approximately 10 times higher. Biogas can be produced from a wide range of raw materials, from organic waste to dedicated energy crops, and can be utilised for various energy services such as heat, combined heat and power or as a vehicle fuel. Biogas systems are therefore affected by a number of different incentives and barriers, including energy-, waste treatment- and agricultural policies. In this paper, different policies and policy instruments, as well as other factors, which influence a potential expansion of Swedish biogas systems, are identified and evaluated. Existing incentives and barriers can be divided into those affecting the production of biogas, and those affecting the utilisation of the biogas. Only a few types of biogas systems are competitive in Sweden today, while the majority needs increased incentives of different kinds to reach profitability. Such incentives are often motivated from an energy and environmental point of view. Due to the complexity of the biogas systems and the many actors involved, all with different interests, the process of implementing adequate policy instruments will require concerted efforts. (c) 2006 Elsevier Ltd. All rights reserved.
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65.
  • Lehtomäki, Anni, et al. (författare)
  • Two-stage anaerobic digestion of energy crops: Methane production, nitrogen mineralisation and heavy metal mobilisation
  • 2006
  • Ingår i: Environmental Technology. - : Selper Ltd. - 1479-487X. ; 27:2, s. 209-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Energy crops (willow, sugar beet and grass silage) were digested ill pilot scale two-stage anaerobic digesters. The specific methane yields obtained were 0.16, 0.38 and 0.39 m(3) kg(-1) added volatile solids (VSadded) for willow, sugar beet and grass, respectively, corresponding to yearly gross energy yields of 15, 53 and 26 megawatt-hours (MWh) per hectare. With grass and sugar beets as substrate, 84-85% of the harvestable methane was obtained within 30 days. In pilot scale two-stage digestion of willow and sugar beet, 56 and 85,, of the laboratory scale methane yields were obtained, but digestion of grass in two-stage reactors yielded 5% more methane than digestion in laboratory scale completely mixed low solids systems, possibly due to the pH conditions favourable to hydrolysis in the two-stage system. In digestion of grass and sugar beet the liquid at the end of digestion was rich in ammonium nitrogen, and the nitrogen in the substrate was efficiently mineralised. The results show that heavy metal concentrations are not likely to limit the utilisation of residues from digestion of nonmetal accumulating crops. Efficient mobilisation of heavy metals during the acidic phase of digestion revealed the possibility of removing metals from leachate generated in two-stage anaerobic digestion of phytoextracting crops.
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66.
  • Liu, Jing, et al. (författare)
  • Immobilised activated sludge based biosensor for biochemical oxygen demand measurement
  • 2000
  • Ingår i: Biosensors & Bioelectronics. - : Elsevier. - 1873-4235. ; 14:12, s. 883-893
  • Tidskriftsartikel (refereegranskat)abstract
    • A biochemical oxygen demand (BOD) sensor, based on an immobilised mixed culture of microorganisms in combination with a dissolved oxygen electrode, has been developed for the purpose of on-line monitoring of the biological treatment process for waste and wastewater. The sensor was designed for easy replacement of the biomembrane, thereby making it suitable for short-term use. The drawbacks of activated sludge based sensor, such as short sensor lifetime, were thereby circumvented. The sensor BOD measurements were carried out in the kinetic mode using a flow injection system, resulting in 25 s for one measurement followed by 4-8 min recovery time. Based on the results of normalised sensor responses, the OECD synthetic wastewater was considered to be a more suitable calibration solution in comparison with the GGA solution. Good agreement was achieved between the results of the sensor BOD measurement and those obtained from BOD5 analysis of a wastewater sample from a food-processing factory. Reproducibility of responses using one sensor was below +/-5.6% standard deviation. Reproducibility of responses using different sensors was within acceptable bias limits, viz. +/-15% standard deviation.
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67.
  • Mshandete, Anthony, et al. (författare)
  • Effect of aerobic pre-treatment on production of hydrolases and volatile fatty acids during anaerobic digestion of solid sisal leaf decortications residues
  • 2008
  • Ingår i: African Journal of Biochemistry Research. - : Academic Journals. - 1996-0778. ; 2:5, s. 111-119
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of aerobic pretreatment on the production of hydrolases and volatile fatty acids during anaerobic digestion of solid sisal decortications leaf residue (SLDR) was investigated. Batch solid waste bioreactors with working volume of 2 litres were used in this study. Batch loads of aerobically treated or untreated sisal leaf residue inoculated with activated sludge mixed culture were packed into the bioreactors and operated anaerobically for 400 h. The fermentation products were mainly (mg/g total volatile fatty acids, VFAs): acetic acid (287), n-butyric acid (201), n-valeric acid (96) and caproic acid (62) as well as with low amounts of propionic acid and iso-butyric acid for aerobic pre-treated sisal leaf waste solids. Contrarily, for the untreated system, the fermentation products were chiefly (mg/g total volatile fatty acids): propionic acid (317), iso-butyric acid (276), n-butyric acid (96), acetic acid (84) and insignificant amounts of n-valeric acid, iso-valeric acid and caproic acid. Although the activities of hydrolytic enzymes found were similar for both treated and untreated SLDR, proportions of VFAs obtained with the former residues appeared to be better substrates for biomethanantion than those obtained from the latter substrates. These results indicated the potential of aerobic pre-treatment for enhanced bioconversion of SLDR. The present study, reports for the first time the types and levels of VFAs and hydrolases produced during anaerobic digestion of aerobic pre-treated SLDR and could be used as a basis for designing a pilot scale process.
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68.
  • Mshandete, Anthony, et al. (författare)
  • Effect of particle size on biogas yield from sisal fibre waste
  • 2006
  • Ingår i: Renewable Energy. - : Elsevier. - 0960-1481. ; 31:14, s. 2385-2392
  • Tidskriftsartikel (refereegranskat)abstract
    • The degradation and biogas production potential of sisal fibre waste could be significantly increased by pre-treatment for reduction of particle size. Batch-wise anaerobic digestion of sisal fibre waste was carried out in 1-l digesters with fibre sizes ranging from 2 to 100 mm, at an ambient temperature of 33 °C. Sediment from a stabilisation pond at a sisal production plant was used as starter seed. Total fibre degradation increased from 31% to 70% for the 2 mm fibres, compared to untreated sisal fibres. Furthermore, the results confirmed that methane yield was inversely proportional to particle size. Methane yield increased by 23% when the fibres were cut to 2 mm size and was 0.22 m3 CH4/kg volatile solids, compared to 0.18 m3 CH4/kg volatile solids for untreated fibres. By anaerobic digestion and biogas production, the 148,000 tonne of waste sisal fibres generated annually in Tanzania could yield 22 million m3 of methane, and an additional 5 million m3 of methane if pre-treatment by size reduction to 2 mm was applied.
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69.
  • Mshandete, Anthony, et al. (författare)
  • Enhancement of anaerobic batch digestion of sisal pulp waste by mesophilic aerobic pre-treatment
  • 2005
  • Ingår i: Water Research. - : Elsevier. - 1879-2448. ; 39:8, s. 1569-1575
  • Tidskriftsartikel (refereegranskat)abstract
    • Pre-treatment of sisal pulp prior to its anaerobic digestion was investigated using an activated sludge mixed culture under aerobic conditions in batch bioreactors at 37 degrees C. The progression of aerobic pre-treatment of the residue in relation to the activities of some extracellular hydrolytic enzymes in the slurry was monitored. The highest activity of hydrolytic enzymes was obtained at 9 h of pre-treatment. Filter paper cellulase had a maximum activity of 0.90 IU/ml, while carboxymethyl cellulase, amylase and xylanase were produced to a maximum of about 0.40 IU/ml. The methane yield obtained after anaerobic digestion of the pre-treated pulp ranged between 0.12 and 0.24 m(3) CH4/kg VS added. The highest and lowest values were obtained for 9 and 72 h of pre-treatment, respectively. Nine hours of pre-treatment of sisal pulp prior to anaerobic digestion demonstrated a 26 % higher methane yield when compared to the sisal pulp without pre-treatment. The consortia of microorganisms in activated sludge demonstrated a useful potential in the production of hydrolases acting on major macromolecules of sisal pulp. The fact that a correlation was observed between high enzyme activity and high methane yield at 9h of aerobic pre-treatment suggests that such a short pretreatment period could be an alternative option for increasing solubilization of sisal pulp and promoting methane productivity. (c) 2005 Elsevier Ltd. All rights reserved.
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70.
  • Mshandete, Anthony Manoni, et al. (författare)
  • Performance of biofilm carriers in anaerobic digestion of sisal leaf waste leachate
  • 2008
  • Ingår i: Electronic Journal of Biotechnology. - : Pontificia Universidad Católica de Valparaíso. - 0717-3458. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Three methanogenic biofilm bioreactors were studied to evaluate the performance of three types of carriers. The carrier material were consisted of sisal fibre waste, pumice stone and porous glass beads, and the bioprocess evaluated was the methanogenesis anaerobic digestion of sisal leaf waste leachate. Process performance was investigated by increasing the organic loading rate (OLR) step-wise. The best results were obtained from the bioreactor packed with sisal fibre waste. It had the highest chemical oxygen demand ( COD) removal efficiencies in the range of 80-93% at OLRs in the range of 2.4-25 g COD L(-1)d(-1). The degradation pattern of volatile fatty acids (VFAs) showed that the degradation of propionate was limiting at higher OLRs. The stable pH and higher partial alkalinity (PA) of the outflow illustrated that packed-bed bioreactors have a good ability to withstand the variations in load and volatile fatty acid concentrations that can occur in a two-stage anaerobic process. In conclusion, sisal fibre waste was shown to be a novel promising biofilm carrier and would work very well in methanogenic biofilm bioreactors treating sisal leaf tissue waste leachate. Furthermore both sisal wastes are available in the neighbourhood of sisal industries, which makes anaerobic digestion scale up at sisal factory level feasible and cost-effective.
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