| 1. |
- Jannasch, Anna-Karin, et al.
(författare)
-
EN KUNSKAPSSYNTES OM ELEKTROBRÄNSLEN FRÅN BIOLOGISKA PROCESSER
- 2017
-
Rapport (refereegranskat)abstract
- Sverige har som mål att ha 100% förnybar kraftproduktion år 2040. Detta skall uppnås genom attbl.a. kraftigt bygga ut den intermittenta kraftproduktionen med t.ex. vindkraft. En ökad andel vindkraftställer dock krav på en ökad tillgång av energilagring och balans- och/eller reglerkraft. Detfinns också andra svenska högt uppsatta miljö- och klimatmål samt ambitioner såsom fossiloberoendetransportsektor 2030, ett koldioxidneutralt samhälle 2045 och att Sverige skall bli ledande påatt ta hand om och återanvända sitt avfall i en cirkulär ekonomi.Kombinationen power-to-gas och biogasproduktion kan på olika sätt bidra till att nå samtliga ovanbeskrivna mål genom att göra det framtida elsystemet flexiblare samtidigt som tillgänglig biomassa,t.ex. gödsel och biologisk nedbrytbart avfall, utnyttjas mer effektivt för ökad produktion avförnybara drivmedel och/eller kemikalier från samma mängd biogassubstrat. Konceptet bygger påatt omvandla billig förnybar el, via elektrolys, till vätgas (dvs. power-to-gas) som tillåts reagera vidaremed koldioxiden i rå biogas via s.k. elektrobränsleprocesser.Det finns idag både termokemiska och biologiska elektrobränsleprocesser för metanproduktion.Det finns också biologisk gasfermentering för produktion av flytande elektrobränslen, t.ex. bioalkoholer.Bland biogasproducenter finns idag ett växande intresse för de olika elektrobränsleprocessernaeftersom de på sikt skulle kunna ge mer lönsamma, produktflexibla och mindre marknadskänsligabiogasanläggningar. Den allmänna uppfattningen hos den svenska biogasbranschen ärdock att det är svårt att på ett lättillgängligt sätt få grepp om vad den teknoekonomiska prestandanoch mognadsgraden för de olika elektrobränsleprocesserna idag är, särskilt vad gäller de biologiska.Denna kunskapssyntes syftar till att tillgodose detta behov och innefattar elektrobränsleprocessernain-situ och ex-situ metanisering samt biologisk gasfermentering, samt med termokemisk metaniseringsom referensprocess. Möjligheten att kombinera elektrobränsleprocesserna med och/ellerersätta konventionell biogasuppgradering undersöks och diskuteras också. De huvudsakliga slutsatsernai studien summeras nedan.Genom att utnyttja billig el och elektrobränsleprocesser i kombination med koldioxidöverskott frånbiogasproduktion kan metanproduktionen från en och samma mängd substrat öka upp till det dubbla.Samtidigt kan konventionell biogasuppgradering för biometanproduktion slopas under förutsättningatt tillräcklig mängd vätgas finns tillgänglig. Den stora utmaningen för denna process ärdock kostnaden och det finns behov av fortsatt FoU inom området för att elektrobränsleprocessernaskall kunna bli ett kostnadsekonomiskt alternativ för svenska biogasproducenter.Av de undersökta elektroprocesserna är termokemisk metanisering den mest mogna tekniken(Technology Readiness Level, TRL=7-8). Processen bygger på termokatalytisk omvandling och äreffektiv, generar högvärdig värme och kan ersätta konventionell biogasuppgradering förutsatt tillgångpå tillräcklig mängd vätgas. Processen är dessutom snabb och reaktorerna som placeras nedströms(ex-situ) biogasreaktorn är kompakta. En primär utmaning med processen är dock att katalysatorernaär känsliga för vanligt förekommande biogasföroreningar (t.ex. svavel), vilket gör attuppströms gasrening krävs. En annan utmaning är att processen sker vid hög temperatur (300-700°C) och tryck (vanligtvis ≤20 bar) vilket medför att uppstartstiden från kallt tillstånd blir relativtlång (timmar). Processen har slutligen relativt låg tolerans mot svängningar i gaskvalité (H2:CO2)och variationer i temperatur vilket medför att uppströms vätgaslager behövs vid intermittent drift.Vid biologisk metanisering (in-situ och ex-situ) omvandlas koldioxid och vätgas till metan medhjälp av mikroorganismer. Ingen katalysator behövs och mikroorganismerna är självproducerande.Reaktionen sker vanligtvis vid atmosfärstryck och låg temperatur (37-60°C). Tack vare den lågadrifttemperaturen är uppstartstiden från kallt tillstånd snabb (minuter). Processerna har, i motsatstill termokemisk metanisering, också mycket hög tolerans mot gasföroreningar (sulfider) och ingeneller mycket begränsad uppströms gasrening krävs.I likhet med termokemisk metanisering är ex-situ biologisk metanisering effektiv och kan ersättakonventionell biogasuppgradering. Till skillnad mot termokemisk metanisering är processen tolerantmot svängningar i gassammansättning (H2:CO2) och kan köras intermittent utan uppströmsvätgaslager. Processen är däremot långsam och kräver betydligt mer voluminösa reaktorer (10-1000 ggr större än vid termokemisk). Ex-situ biologisk metanisering är mindre mogen än termokemiskmetanisering (TRL=6-7).Vid In-situ metanisering tillförs vätgasen direkt till rötningskammaren och önskvärd metaniseringsker parallellt med biogasprocessen. Detta innebär att inte behöver investera i någon separat kostsammetaniseringsreaktor. Nackdelen är att det finns begränsade möjligheter till att ändra och optimeradriftbetingelserna (T, p, omrörning) mot metaniseringsprocessen utan att störa rötningsprocessen.Omvandlingseffektiviteten blir därför betydligt lägre än för ex-situ metanisering (från 52till 75% metanhalt har som bäst demonstrerats) och processen kan inte ersätta konventionell biogasuppgradering.En annan utmaning är att processen är känslig för vätgasinhibering vilket innebäratt vätgaslager behövs uppströms rötningskammaren vid intermittent drift. Mognadsgraden är lägreän för både termokemisk och ex-situ biologisk metansiering (TRL=4-5).Biologisk gasfermentering ökar flexibiliteten hos en biogasanläggning och kan minska risken avinvesteringen eftersom processen kan anpassas till marknadsdrivkrafter. Flexibiliteten begränsasdock av kostnaden för produktuppgraderingen där etanol t.ex kräver dyrare och en annan typ avuppgradering än vad t.ex långa fettsyror gör. I jämförelse med metanisering är det en fördel medproduktion av flytande bränslen när en anläggning ligger långt från en existerande gasinfrastruktur.Idag produceras främst etanol kommersiellt, men forskning och utveckling för produktion av långafettsyror och butanediol pågår. Dessa produkter har ett högre marknadsvärde och medför en merkostnadseffektiv uppgradering. Teknikutvecklingen och kommersialiseringen har utgått från fermenteringav syngas från förgasning och koldioxid från stålindustrin. Produktionen av koldioxidfrån svenska biogasanläggningar uppskattas vara ca en tiondel för låg för att en kostnadseffektivetanolproduktion skall kunna vara möjlig. Processen bedöms därför vara den minst mogna av deundersökta alternativen (TRL=2-4). I övrigt är gasfermentering en biologisk process som inneharliknande fördelar och utmaningar som beskrivits ovan för biologisk ex-situ metanisering.
|
|
| 2. |
|
|
| 3. |
- Bielen, Abraham A. M., et al.
(författare)
-
Pyrophosphate as a central energy carrier in the hydrogen-producing extremely thermophilic Caldicellulosiruptor saccharolyticus
- 2010
-
Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 307:1, s. 48-54
-
Tidskriftsartikel (refereegranskat)abstract
- The role of inorganic pyrophosphate (PPi) as an energy carrier in the central metabolism of the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus was investigated. In agreement with its annotated genome sequence, cell extracts were shown to exhibit PPi-dependent phosphofructokinase and pyruvate phosphate dikinase activity. In addition, membrane-bound pyrophosphatase activity was demonstrated, while no significant cytosolic pyrophosphatase activity was detected. During the exponential growth phase, high PPi levels (approximately 4 +/- 2 mM) and relatively low ATP levels (0.43 +/- 0.07 mM) were found, and the PPi/ATP ratio decreased 13-fold when the cells entered the stationary phase. Pyruvate kinase activity appeared to be allosterically affected by PPi. Altogether, these findings suggest an important role for PPi in the central energy metabolism of C. saccharolyticus.
|
|
| 4. |
- Björkmalm, Johanna, et al.
(författare)
-
A non-linear model of hydrogen production by Caldicellulosiruptor saccharolyticus for diauxic-like consumption of lignocellulosic sugar mixtures
- 2018
-
Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 11:1, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Caldicellulosiruptor saccharolyticus is an attractive hydrogen producer suitable for growth on various lignocellulosic substrates. The aim of this study was to quantify uptake of pentose and hexose monosaccharides in anindustrial substrate and to present a kinetic growth model of C. saccharolyticus that includes sugar uptake on defined and industrial media. The model is based on Monod and Hill kinetics extended with gas-to-liquid mass transfer and acybernetic approach to describe diauxic-like growth.Results: Mathematical expressions were developed to describe hydrogen production by C. saccharolyticus consuming glucose, xylose, and arabinose. The model parameters were calibrated against batch fermentation data. Theexperimental data included four different cases: glucose, xylose, sugar mixture, and wheat straw hydrolysate (WSH) fermentations. The fermentations were performed without yeast extract. The substrate uptake rate of C. saccharolyticuson single sugar-defined media was higher on glucose compared to xylose. In contrast, in the defined sugar mixture and WSH, the pentoses were consumed faster than glucose. Subsequently, the cultures entered a lag phasewhen all pentoses were consumed after which glucose uptake rate increased. This phenomenon suggested a diauxic-like behavior as was deduced from the successive appearance of two peaks in the hydrogen and carbon dioxideproductivity. The observation could be described with a modified diauxic model including a second enzyme system with a higher affinity for glucose being expressed when pentose saccharides are consumed. This behavior was morepronounced when WSH was used as substrate.Conclusions: The previously observed co-consumption of glucose and pentoses with a preference for the latter was herein confirmed. However, once all pentoses were consumed, C. saccharolyticus most probably expressed anotheruptake system to account for the observed increased glucose uptake rate. This phenomenon could be quantitatively captured in a kinetic model of the entire diauxic-like growth process. Moreover, the observation indicates a regulationsystem that has fundamental research relevance, since pentose and glucose uptake in C. saccharolyticus has only been described with ABC transporters, whereas previously reported diauxic growth phenomena have been correlatedmainly to PTS systems for sugar uptake.
|
|
| 5. |
- Byrne, Eoin, et al.
(författare)
-
Characterization and adaptation of Caldicellulosiruptor strains to higher sugar concentrations, targeting enhanced hydrogen production from lignocellulosic hydrolysates
- 2021
-
Ingår i: Biotechnology for Biofuels. - : BioMed Central Ltd. - 1754-6834. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C.owensensis, C. kronotskyensis, C.bescii, C.acetigenus and C.kristjanssonii, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution (ALE) process. The developed mixed population C.owensensis CO80 was further studied and accompanied by the development of a kinetic model based on Monod kinetics to quantitatively compare it with the parental strain. Results: Mixed populations of Caldicellulosiruptor tolerant to higher glucose concentrations were obtained with C.owensensis adapted to grow up to 80 g/L glucose; other strains in particular C. kristjanssonii demonstrated a greater restriction to adaptation. The C.owensensis CO80 mixed population was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/L glucose, but with reduced volumetric hydrogen productivities (QH2) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of the mixed population C.owensensis CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical sugar concentration of the cells increased fourfold when cultivated at higher concentrations. When co-cultured with the adapted C.saccharolyticus G5 mixed culture at a hydraulic retention time (HRT) of 20 h, C.owensensis constituted only 0.09–1.58% of the population in suspension. Conclusions: The adaptation of members of the Caldicellulosiruptor genus to higher sugar concentrations established that the ability to develop improved strains via ALE is species dependent, with C.owensensis adapted to grow on 80 g/L, whereas C.kristjanssonii could only be adapted to 30 g/L glucose. Although C.owensensis CO80 was adapted to a higher sugar concentration, this mixed population demonstrated reduced QH2 with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated sugar concentrations, this approach does not result in improved fermentation performances at these higher sugar concentrations. Moreover, the observation that planktonic mixed culture of CO80 was outcompeted by an adapted C.saccharolyticus, when co-cultivated in continuous mode, indicates that the robustness of CO80 mixed culture should be improved for industrial application. © 2021, The Author(s).
|
|
| 6. |
- Byrne, Eoin, et al.
(författare)
-
Reduced use of phosphorus and water in sequential dark fermentation and anaerobic digestion of wheat straw and the application of ensiled steam-pretreated lucerne as a macronutrient provider in anaerobic digestion
- 2018
-
Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Current EU directives demand increased use of renewable fuels in the transportation sector but restrict governmental support for production of biofuels produced from crops. The use of intercropped lucerne and wheat may comply with the directives. In the current study, the combination of ensiled lucerne (Medicago sativa L.) and wheat straw as substrate for hydrogen and methane production was investigated. Steam-pretreated and enzymatically hydrolysed wheat straw [WSH, 76% of total chemical oxygen demand (COD)] and ensiled lucerne (LH, 24% of total COD) were used for sequential hydrogen production through dark fermentation and methane production through anaerobic digestion and directly for anaerobic digestion. Synthetic co-cultures of extreme thermophilic Caldicellulosiruptor species adapted to elevated osmolalities were used for dark fermentation. Results: Based on 6 tested steam pretreatment conditions, 5 min at 200 °C was chosen for the ensiled lucerne. The same conditions as applied for wheat straw (10 min at 200 °C with 1% acetic acid) would give similar sugar yields. Volumetric hydrogen productivities of 6.7 and 4.3 mmol/L/h and hydrogen yields of 1.9 and 1.8 mol/mol hexose were observed using WSH and the combination of WSH and LH, respectively, which were relatively low compared to those of the wild-type strains. The combinations of WSH plus LH and the effluent from dark fermentation of WSH plus LH were efficiently converted to methane in anaerobic digestion with COD removal of 85-89% at organic loading rates of COD 5.4 and 8.5 g/L/day, respectively, in UASB reactors. The nutrients in the combined hydrolysates could support this conversion. Conclusions: This study demonstrates the possibility of reducing the water addition to WSH by 26% and the phosphorus addition by 80% in dark fermentation with Caldicellulosiruptor species, compared to previous reports. WSH and combined WSH and LH were well tolerated by osmotolerant co-cultures. The yield was not significantly different when using defined media or hydrolysates with the same concentrations of sugars. However, the sugar concentration was negatively correlated with the hydrogen yield when comparing the results to previous reports. Hydrolysates and effluents from dark fermentation can be efficiently converted to methane. Lucerne can serve as macronutrient provider in anaerobic digestion. Intercropping with wheat is promising.
|
|
| 7. |
- Ekman Nilsson, Anna, et al.
(författare)
-
A review of carbon footprint of Cu and Zn production from primary and secondary sources
- 2017
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 7:9, s. 168-
-
Tidskriftsartikel (refereegranskat)abstract
- Copper (Cu) and zinc (Zn) with their unique propertiesare central for economic growth, quality of life and creation of new jobs. The base-metalproducing sector is, however, under growing public pressure in respect toenergy and water requirements and needs to meet several challenges, includingincreased demand and lower ore grades generally associated with larger resourceuse. The development of technologies for metal production from secondarysources is often motivated by increased sustainability and this paper aims to providefurther insights about one specific aspect of sustainability, namely climatechange. The paper presents a review of carbon footprints (CF) for Cu and Znproduced from primary and secondary raw materials, by analyzing data taken fromscientific literature and the Ecoinvent database. Comparisons are carried outbased on the source of data selected as reference case. In the case of Cu,reduced CF of secondary production is indicated, although there is large datavariation. As for Zn, production of this metal from secondary sources seems to bebeneficial but the number of data and cases to be compared is much smallercompared to Cu. The general variation of data suggests that standardization ofcomparison is needed when assessing the environmental benefits of production inline with the principles of waste valorization, zero waste approach andcircular economy.
|
|
| 8. |
- Ghanim, Bashir, et al.
(författare)
-
Application of KOH modified seaweed hydrochar as a biosorbent of Vanadium from aqueous solution : Characterisations, mechanisms and regeneration capacity
- 2020
-
Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier Ltd. - 2213-3437. ; 8:5
-
Tidskriftsartikel (refereegranskat)abstract
- Vanadium exists as a mobile and toxic trace metal in many alkaline residue leachates. Its removal and recovery not only reduces a global environmental risk but is also critical to the emergence of innovative technologies and the circular economy. In parallel, the use of treated biomass feedstock is receiving increased attention as a low cost adsorbent for toxic metals in wastewater. This study investigated the adsorption of Vanadium (V) from aqueous solution by KOH modified seaweed (Ascophyllum nodosum) hydrochar (HCKOH). The results showed that HCKOH is an effective V(V) adsorbent, achieving maximum uptake of 12.3 mg g-1 at solution pH 4, 60 min contact time and temperature 293 K. The kinetics followed a pseudo second order model with film diffusion controlling the overall adsorption rate. The type I adsorption isotherm was well fitted to a Langmuir model (qm = 12.3 mg g-1, R2 = 0.970, RMSE = 0.66) and a thermodynamic study indicated that the V(V) adsorption was both exothermic and spontaneous. The low enthalpy change (-10.97 kJ mol-1) indicated a weak binding of V(V) to HCKOH pointing to the possibility of V recovery. The impact of co-existing cations on V(V) uptake was negligible for Na(I) and Ga (III) but was reduced slightly for Al(III). Desorption and re-adsorption results (3 cycles) indicated that HCKOH has reusable potential to remove and recover V(V) from waste leachates. © 2020 The Author(s).
|
|
| 9. |
- Henriksson, Gunilla, et al.
(författare)
-
Benchmarking av gödselsamrötning med avloppsslam mot förbränning av häst- och djurparksgödsel
- 2015
-
Rapport (refereegranskat)abstract
- Owners of stables and owners of zoos have difficulty finding an economically sustainable deposition of their produced manure. More than two million tons of horse manure are produced in urban environments in Sweden every year. If the manure cannot be used as fertilizer on farm land it is classified as a waste fraction and should be handled according to current regulations. The manure is a valuable waste fraction that contains both energy and nutrients. If the manure cannot be spread on farm land more applications need to be identified, where the energy and nutrients in the manure can be used. The focus in this study is to investigate possible applications for the usage of horse and zoo manure within Borås municipality where, among other things, a waste water treatment plant and a combined heat and power plant are available. Horse and zoo manure have been investigated in the following applications: co-digestion with sewage sludge at a waste water treatment plant (lab experiments), co-digestion with food waste (theoretical), co-incineration with waste (full scale) and co-incineration with biomass (theoretical). Potential quantity of manure and economical and legal aspects have been studied as well. There is no compilation of the number of horses in the country which makes it hard to estimate the true quantity of manure. The quantity of manure from the zoos are somewhat easier to estimate since the zoo owners are fewer and have knowledge of their manure production. The co-digestions experiments in this study showed that addition of horse manure to digestion can be of interest in many ways, among other things it can give a more stable biogas production and a possible decrease in the Cd/P-ratio in the end product. Horse manure turned out to have a faster degradation rate compared to zoo manure, however the degradation rate was lower than that of sewage sludge. Zoo manure gave a relatively low biogas production compared to horse manure at thermophilic conditions. The co-incineration trial with waste and manure gave no negative effect with regard to emissions and operation. However, the amount of manure added to the incineration trial was low. The theoretical studies regarding the co-incineration with biomass, showed two potential alternatives that need to be investigated further. Interesting aspects to look further upon, based on this study, are for example: • Laws and regulations in the EU regarding manure. • Co-digestion of manure and sewage sludge in a larger scale. • Laws and regulations and costs regarding incineration of manure with biomass.
|
|
| 10. |
|
|
