| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Forgacs, G., et al.
(författare)
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Pretreatment of chicken feather waste for improved biogas production
- 2013
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Ingår i: Applied Biochemistry and Biotechnology. - : Humana Press, Inc.. - 0273-2289 .- 1559-0291. ; 169:7, s. 2016-2028
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the utilization of chicken feather waste as a substrate for anaerobic digestion and improving biogas production by degradation of the compact structure of the feather keratin. In order to increase the digestibility of the feather, different pretreatments were investigated, including thermal pretreatment at 120 °C for 10 min, enzymatic hydrolysis with an alkaline endopeptidase [0.53–2.66 mL/g volatile solids (VS) feathers] for 0, 2, or 24 h at 55 °C, as well as a combination of these pretreatments. The effects of the treatments were then evaluated by anaerobic batch digestion assays at 55 °C. The enzymatic pretreatment increased the methane yield to 0.40 Nm3/kg VSadded, which is 122 % improvement compared to the yield of the untreated feathers. The other treatment conditions were less effective, increasing the methane yield by 11–50 %. The long-term effects of anaerobic digestion of feathers were examined by co-digestion of the feather with organic fraction of municipal solid waste performed with and without the addition of enzyme. When enzyme was added together with the feed, CH4 yield of 0.485 Nm3/kg VS−1 d−1 was achieved together with a stable reactor performance, while in the control reactor, a decrease in methane production, together with accumulation of undegraded feather, was observed.
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| 3. |
- Teghammar, A., et al.
(författare)
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Techno-economic study of NMMO pretreatment and biogas production from forest residues
- 2014
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Ingår i: Applied Energy. - : Pergamon. - 0306-2619 .- 1872-9118. ; 116, s. 125-133
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Tidskriftsartikel (refereegranskat)abstract
- Biogas is nowadays getting more attention as a means for converting wastes and lignocelluloses to green fuels for cars and electricity production. The process of biogas production from N-methylmorpholine oxide (NMMO) pretreated forest residues used in a co-digestion process was economically evaluated. The co-digestion occurs together with the organic fraction of municipal solid waste (OFMSW). The process simulated the milling of the lignocelluloses, NMMO pretreatment unit, washing and filtration of the feedstock, followed by an anaerobic co-digestion, upgrading of the biogas and de-watering of the digestate. The process also took into consideration the utilization of 100,000 DW (dried weight) tons of forest residues and 200,000 DW tons of OFMSW per year. It resulted in an internal rate of return (IRR) of 24.14% prior to taxes, which might be attractive economically. The cost of the chemical NMMO treatment was regarded as the most challenging operating cost, followed by the evaporation of the washing water. Sensitivity analysis was performed on different plant size capacities, treating and digesting between 25,000 and 400,000 DW tons forest residues per year. It shows that the minimum plant capacity of 50,000 DW tons forest residues per year is financially viable. Moreover, different co-digestion scenarios were evaluated. The co-digestion of forest residues together with sewage sludge instead of OFMSW, and the digestion of forest residues only were shown to be non-feasible solutions with too low IRR. Furthermore, biogas production from forest residues was compared with the energy produced during combustion.
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| 4. |
- Akinbomi, J G, et al.
(författare)
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Current challenges of high-solid anaerobic digestion and possible measures for its effective applications : a review
- 2022
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Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Nature. - 2731-3654. ; 15:1
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Forskningsöversikt (refereegranskat)abstract
- The attention that high solids anaerobic digestion process (HS-AD) has received over the years, as a waste management and energy recovery process when compared to low solids anaerobic digestion process, can be attributed to its associated benefits including water conservation and smaller digester foot print. However, high solid content of the feedstock involved in the digestion process poses a barrier to the process stability and performance if it is not well managed. In this review, various limitations to effective performance of the HS-AD process, as well as, the possible measures highlighted in various research studies were garnered to serve as a guide for effective industrial application of this technology. A proposed design concept for overcoming substrate and product inhibition thereby improving methane yield and process stability was recommended for optimum performance of the HS-AD process.
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| 5. |
- Awasthi, Mukesh Kumar, et al.
(författare)
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Biochemical engineering for elemental sulfur from flue gases through multi-enzymatic based approaches – A review
- 2024
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 914
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Forskningsöversikt (refereegranskat)abstract
- Flue gases are the gases which are produced from industries related to chemical manufacturing, petrol refineries, power plants and ore processing plants. Along with other pollutants, sulfur present in the flue gas is detrimental to the environment. Therefore, environmentalists are concerned about its removal and recovery of resources from flue gases due to its activation ability in the atmosphere to transform into toxic substances. This review is aimed at a critical assessment of the techniques developed for resource recovery from flue gases. The manuscript discusses various bioreactors used in resource recovery such as hollow fibre membrane reactor, rotating biological contractor, sequential batch reactor, fluidized bed reactor, entrapped cell bioreactor and hybrid reactors. In conclusion, this manuscript provides a comprehensive analysis of the potential of thermotolerant and thermophilic microbes in sulfur removal. Additionally, it evaluates the efficacy of a multi-enzyme engineered bioreactor in this process. Furthermore, the study introduces a groundbreaking sustainable model for elemental sulfur recovery, offering promising prospects for environmentally-friendly and economically viable sulfur removal techniques in various industrial applications.
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| 6. |
- Awasthi, S K, et al.
(författare)
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Multi-criteria research lines on livestock manure biorefinery development towards a circular economy : From the perspective of a life cycle assessment and business models strategies
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 341
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Tidskriftsartikel (refereegranskat)abstract
- Livestock manure (LSM) is a profitable waste if handled sensibly, but simultaneously it imposes several environmental and health impacts if managed improperly. Several approaches have been adopted globally to cartel the problem associated with LSM management and recovery of value-added products, still, technological innovation needs further upgradation in consideration with the environment, energy, and economy. This review delivered a vibrant portrait of manure management, which includes, bioenergy generation and resource recovery strategies, their current scenario, opportunities, challenges, and prospects for future researches along with global regulations and policies. Several bioenergy generation and nutrient recoveries technologies have been discussed in details, still, the major glitches allied with these technologies are its high establishment costs, operational costs, manure assortment, and digestate handling. This review also discussed the techno-economic assessment (TEA) and life cycle assessment (LCA) of LSM management operation in the context of their economical and environmental sustainability. Still, extensive researches needed to build an efficient manure management framework to advance the integrated bioenergy production, nutrients recycling, and digestate utilization with least environmental impacts and maximal economical gain, which has critically discussed in the current review.
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| 7. |
- Harmini, S, et al.
(författare)
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Fungal Pretreatment of Oil Palm Empty Fruit Bunch: Effect of Manganese and Nitrogen
- 2013
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Ingår i: Cellulose Chemistry and Technology. - 0576-9787. ; 47:9-10, s. 751-757
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Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) was biologicallypretreated usingPleurotus floridanusLIPIMC996 supplementedwith various concentrations of manganese and nitrogen and incubated for 35 days at 30°C, and enzyme activities ofmanganese peroxidase (MnP) and laccase were examined. When OPEFB was supplemented with manganese, thehighest lignin reduction was achieved up to 25.0±5.6% at the addition of 200 μg Mn2+/g OPEFB.In addition,PleurotusfloridanusLIPIMC996 grew best on OPEFB supplemented with 800μg Mn2+/g OPEFB. When OPEFB wassupplemented with nitrogen, the highest lignin reduction was achieved up to 27.2± 3.5% at the additionof 20 mMnitrogen. The best growth ofPleurotus floridanuswas also achieved with the addition of 20 mM nitrogen. The additionof nitrogen and manganese on OPEFB did not significantly affect the activity of MnP and laccase.
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| 8. |
- Horváth, I. S., et al.
(författare)
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Effects of furfural on anaerobic continuous cultivation of Saccharomyces cerevisiae
- 2001
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 75:5, s. 540-549
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Tidskriftsartikel (refereegranskat)abstract
- Furfural is an important inhibitor of yeast metabolism in lignocellulose-derived substrates. The effect of furfural on the physiology of Saccharomyces cerevisiae CBS 8066 was investigated using anaerobic continuous cultivations. Experiments were performed with furfural in the feed medium (up to 8.3 g/L) using three dierent dilution rates (0.095, 0.190, and 0.315 h-1). The measured concentration of furfural was low (<0.1 g/L) at all steady states obtained. However, it was not possible to achieve a steady state at a specific conversion rate of furfural, qf, higher than approximately 0.15 g/g·h. An increased furfural concentration in the feed caused a decrease in the steady-state glycerol yield. This agreed well with the decreased need for glycerol production as a way to regenerate NAD+, i.e., to function as a redox sink because furfural was reduced to furfuryl alcohol. Transient experiments were also performed by pulse addition of furfural directly into the fermentor. In contrast to the situation at steady-state conditions, both glycerol and furfuryl alcohol yields increased after pulse addition of furfural to the culture. Furthermore, the maximum specific conversion rate of furfural (0.6 g/g·h) in dynamic experiments was significantly higher than what was attainable in the chemostat experiments. The dynamic furfural conversion could be described by the use of a simple Michaelis-Menten-type kinetic model. Also furfural conversion under steady-state conditions could be explained by a Michaelis-Menten-type kinetic model, but with a higher anity and a lower maximum conversion rate. This indicated the presence of an additional component with a higher anity, but lower maximum capacity, either in the transport system or in the conversion system of furfural.
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| 9. |
- Jeihanipour, A, et al.
(författare)
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High-rate biogas production from waste textiles using a two-stage process
- 2013
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Ingår i: Renewable energy. - : Pergamon. - 0960-1481 .- 1879-0682. ; 52, s. 128-135
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of a two-stage Continuously Stirred Tank Reactor (CSTR), modified as Stirred Batch Reactor (SBR), and Upflow Anaerobic Sludge Blanket Bed (UASB) process in producing biogas from waste textiles was investigated under batch and semi-continuous conditions. Single-stage and two-stage digestions were compared in batch reactors, where 20 g/L cellulose loading, as either viscose/polyester or cotton/polyester textiles, was used. The results disclosed that the total gas production from viscose/polyester in a two-stage process was comparable to the production in a single-stage SBR, and in less than two weeks, more than 80% of the theoretical yield of methane was acquired. However, for cotton/polyester, the two-stage batch process was significantly superior to the single-stage; the maximum rate of methane production was increased to 80%, and the lag phase decreased from 15 days to 4 days. In the two-stage semi-continuous process, where the substrate consisted of jeans textiles, the effect of N-methylmorpholine-N-oxide (NMMO) pretreatment was studied. In this experiment, digestion of untreated and NMMO-treated jeans textiles resulted in 200 and 400 ml (respectively) methane/g volatile solids/day (ml/g VS/day), with an organic loading rate (OLR) of 2 g VS/L reactor volume/day (g VS/L/day); under these conditions, the NMMO pretreatment doubled the biogas yield, a significant improvement. The OLR could successfully be increased to 2.7 g VS/L/day, but at a loading rate of 4 g VS/L/day, the rate of methane production declined. By arranging a serial interconnection of the two reactors and their liquids in the two-stage process, a closed system was obtained that converted waste textiles into biogas.
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| 10. |
- Karimi, K., et al.
(författare)
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Ethanol production from dilute-acid pretreated rice straw by simultaneous saccharification and fermentation with Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae
- 2006
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Ingår i: Enzyme and microbial technology. - : Elsevier BV. - 0141-0229 .- 1879-0909. ; 40:1, s. 138-144
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Tidskriftsartikel (refereegranskat)abstract
- Ethanol production from rice straw by simultaneous saccharification and fermentation (SSF) with Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae was investigated and compared with pure cellulose, Avicel, as a reference. The straw was pretreated with dilute-acid hydrolysis. The SSF experiments were carried out aerobically and anaerobically at 38 °C, 50 g/l dry matter (DM) solid substrate concentration and 15 or 30 filter paper unit (FPU)/g DM of a commercial cellulase. The experiments were ended after 7 days, while an average of 2-3 days were usually enough to achieve the maximum ethanol yield. All the strains were able to produce ethanol from the pretreated rice straw with an overall yield of 40-74% of the maximum theoretical SSF yield, based on the glucan available in the solid substrate. R. oryzae had the best ethanol yield as 74% from rice straw followed by M. indicus with an overall yield of 68% with 15 FPU/g DM of cellulase. Glycerol was the main byproduct of the SSF by M. indicus and S. cerevisiae with yields 117 and 90 mg/g of equivalent glucose in the pretreated straw, respectively, while R. oryzae produced lactic acid as the major byproduct with yield 60 mg/g glucose equivalent in pretreated rice straw under anaerobic conditions.
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