| 1. |
- Agnihotri, Swarnima, et al.
(författare)
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Integrated products biorefinery options within the Swedish pulp and paper industry: Current status
- 2024
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Ingår i: Sustainable Chemistry for the Environment. - 2949-8392. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Pulp and paper manufacturing ranks as one of the most water and energy-intensive sectors globally, invariablyleading to significant environmental pollution e.g. issues related to air pollution and waste disposal. Also, asglobal competition intensifies, prices of forest products are expected to keep decreasing. To ensure their viability,traditional producers must augment their revenue streams by diversifying into the production of bioenergy andbiomaterials, alongside traditional wood, pulp, and paper products. A feasible solution is the integrated productsbiorefineries which provide a distinctive chance to pulp and paper industry to enhance revenues as well asreduce their environmental impact. Since pulp and paper stands as the predominant industry in Sweden, thisreview article explores the emerging biorefinery process options and main technological pathways beingdeveloped within Swedish pulp and paper mills. It also delves into the significant challenges that are beingencountered in this evolving landscape and what possibilities lie ahead for responsible and sustainable pulp andpaper operations.
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| 2. |
- Akintunde, Moyinoluwa, et al.
(författare)
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Bacterial Cellulose Production from agricultural Residues by two Komagataeibacter sp. Strains
- 2022
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Ingår i: Bioengineered. - : Informa UK Limited. - 2165-5979 .- 2165-5987. ; 13:4, s. 10010-10025
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural residues are constantly increasing with increased farming processes, and improper disposal is detrimental to the environment. Majority of these waste residues are rich in lignocellulose, which makes them suitable substrate for bacterial fermentation in the production of valueadded products. In this study, bacterial cellulose (BC), a purer and better form of cellulose, was produced by two Komagataeibacter sp. isolated from rotten banana and kombucha drink using corncob (CC) and sugarcane bagasse (SCB) enzymatic hydrolyzate, under different fermentation conditions, that is, static, continuous, and intermittent agitation. The physicochemical and mechanical properties of the BC films were then investigated by Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetry analysis, Field Emission Scanning Electron Microscopy (FESEM), and Dynamic mechanical analysis. Agitation gave a higher BC yield, with Komagataeibacter sp. CCUG73629 producing BC from CC with a dry weight of 1.6 g/L and 1.4 g/L under continuous and intermittent agitation, respectively, compared with that of 0.9 g/L in HS medium. While BC yield of dry weight up to 1.2 g/L was obtained from SCB by Komagataeibacter sp. CCUG73630 under continuous agitation compared to that of 0.3 g/L in HS medium. FTIR analysis showed BC bands associated with cellulose I, with high thermal stability. The FE-SEM analysis showed that BC fibers were highly ordered and densely packed. Although the BC produced by both strains showed similar physicochemical and morphological properties, the BC produced by the Komagataeibacter sp. CCUG73630 in CC under intermittent agitation had the best modulus of elasticity, 10.8 GPa and tensile strength, 70.9 MPa. [GRAPHICS]
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| 3. |
- Alinezhad, S., et al.
(författare)
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Expression of keratinase gene in Bacillus megaterium using an expression vector of pHIS1525.SPlipA and utilization of the resulting recombinant strain for chicken feather degradation prior to biogas production
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An increasing quantity of chickens is being utilized annually in the poultry industry, producing a huge volume of chicken feather waste which presents a high quality supply of keratin. Keratinases possessing high level of keratinolytic activity on insoluble keratin play a crucial role in hydrolyzing chicken feathers. Ever since the discovery of proteolytic ability as well as water solubility of keratinase, many industrial processes regarding keratinase application have been developed. A recently invented application to handle poultry waste is to utilize feathers for biogas production. Obviously, large amount of keratinase is required to break down the keratin prior to further conversion to biogas. Previously, several researches have shown that certain bacteria are able to produce keratinase but it is still a challenge to find out which bacteria is the most reliable source for the production with high efficiency. These challenges gave rise to the molecular biologists to bring the focus on gene cloning to develop recombinant strains resulting in overproduction of keratinase. Over the course of various cloning and expression experiments of similar proteins, it was found that Bacillus megaterium could be a susceptible host cell for keratinase production. In our study, the keratinase gene from the chromosomal DNA of Bacillus licheniformis ATCC®53757 was PCR amplified and subsequently cloned into Bacillus megaterium expression vector, pHIS1525.SPlipA. Bacillus megaterium ATCC®14945 strain was transformed with the recombinant plasmid, pKERHIS1525.SPlipA. The KER gene was expressed under xylose inducible promoter, and the product was then purified using Ni-NTA affinity chromatography. After 18 h of incubation an extracellular keratinase activity of 29U ml-1 was achieved (one unit of activity was determined as the amount of enzyme required to an increase of 0.01 in A420 after 30 min of incubation at 37°C). The recombinant strain was further examined for feather degradation using intact chicken feather waste as carbon source. The chopped chicken feathers were partially degraded by the recombinant strain after three days of incubation and the total macroscopic digestion was ultimately observed after seven days resulting in a yellowish peptide rich fermentation broth. The biogas potential of the hydrolysate will be compared with that of untreated feathers by performing anaerobic batch digestion experiments.
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| 4. |
- Alriksson, Björn, et al.
(författare)
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Ammonium hydroxide detoxification of spruce acid hydrolysates
- 2005
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Ingår i: Applied Biochemistry and Biotechnology. - 0273-2289 .- 1559-0291. ; 121, s. 911-922
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Tidskriftsartikel (refereegranskat)abstract
- When dilute-acid hydrolysates from spruce are fermented to produce ethanol, detoxification is required to make the hydrolysates fermentable at reasonable rates. Treatment with alkali, usually by overliming, is one of the most efficient approaches. Several nutrients, such as ammonium and phosphate, are added to the hydrolysates prior to fermentation. We investigated the use of NH4OH for simultaneous detoxification and addition of nitrogen source. Treatment with N-H4OH compared favorably with Ca(OH)(2), Mg(OH)(2), Ba(OH)(2), and NaOH to improve fermentability using Saccharomyces cerevisiae. Analysis of monosaccharides, furan aldehydes, phenols, and aliphatic acids was performed after the different treatments. The NH4OH treatments, performed at pH 10.0, resulted in a substantial decrease in the concentrations of furfural and hydroxymethylfurfural. Under the conditions studied, NH4OH treatments gave better results than Ca(OH)(2) treatments. The addition of an extra nitrogen source in the form of NH4Cl at pH 5.5 did not result in any improvement in fermentability that was comparable to NH4OH treatments at alkaline conditions. The addition of CaCl2 or NH4Cl at pH 5.5 after treatment with NH4OH or Ca(OH)(2) resulted in poorer fermentability, and the negative effects were attributed to salt stress. The results strongly suggest that the highly positive effects of NH4OH treatments are owing to chemical conversions rather than stimulation of the yeast cells by ammonium ions during the fermentation.
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| 5. |
- Alriksson, Björn, et al.
(författare)
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Overexpression of Saccharomyces cerevisiae transcription factor and multidrug resistance genes conveys enhanced resistance to lignocellulose-derived fermentation inhibitors
- 2010
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Ingår i: Process Biochemistry. - : Elsevier. - 1359-5113 .- 1873-3298. ; 45:2, s. 264-271
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Tidskriftsartikel (refereegranskat)abstract
- The presence of fermentation inhibitors in lignocellulose hydrolysates is an obstacle for achieving efficient fermentation of lignocellulose hydrolysates to ethanol and other commodities. In this investigation, the possibility of generating more inhibitor-resistant Saccharomyces cerevisiae by genetic engineering was explored. Based on previous results from studies of deletion mutants, three S. cerevisiae genes (ATR1, FLR1, YAP1) involved in multidrug resistance and stress response of yeast were selected for overexpression in three S. cerevisiae strains. The resistance of the transformed strains to lignocellulose-derived fermentation inhibitors and a dilute-acid spruce hydrolysate was evaluated in fermentation experiments. Overexpression of FLR1 resulted in enhanced resistance to the phenolic inhibitor coniferyl aldehyde and the furan aldehyde HMF (5-hydroxymethyl-2-furaldehyde). Overexpression of ATR1 conferred increased resistance to coniferyl aldehyde. Strains overexpressing YAP1, which encodes a transcription factor, displayed increased resistance to coniferyl aldehyde, HMF, and the spruce hydrolysate. An ethanol productivity of 0.17 g ethanol × l−1 × h−1 was achieved for a YAP1-overexpressing transformant cultivated in spruce hydrolysate, whereas a control transformant, which did not overexpress YAP1, only reached a productivity of 0.05 g ethanol × l−1 × h−1.
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| 6. |
- Andreas, Billy, et al.
(författare)
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Effects of Acid : Pretreatment of Inoculums and Substrate Concentration for Batch Thermophilic Biohydrogen Production from Starch - Rich Synthetic Wastewater
- 2011
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Ingår i: lntemational Symposium on Southeast Asian Water Environment Part 1.
-
Konferensbidrag (refereegranskat)abstract
- The objective of this study is to investigate the biohydrogen production in a thermophilic temperature at various acid - pretreatment of inoculums and substrate concentration of starch - ri ch synthetic wastewater, i.e. tapioca and potato synthetic one . Batch tests were conducted in 118 mL batch reactor s under thermophilic temperature (55 0 C) by natu ral mixed culture from a biogas plant. Biohydrogen production in ten days fermentation at a range of acid - pretreatment inoculum s from 5 to 6 and substrate synthetic tapioca and pot ato wastewater concentration from 5 to 50 g/L were evaluated. The maximum yield of 19.06 mmol H 2 /gVS added for synthetic potato wastewater and of 18.15 mmol H 2 /g VS added for synthetic tapioca wastewater were obtained at acid - pretreatment of inoculums of 5 and the substrate concentration of 10 g/L. The content of biohydrogen in th e biogas has a range between 41% and 43%, moreover there was no significant methane observed. For the pH inoculums of 5, acetic and n - butyric acids were found as main volatile fatty acid s in the biohydrogen fermentation . The results suggested that the starch - rich synthetic wastewater is one of potential sources of renewable energy from organic wastewater to produce biohydrogen.
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| 7. |
- Aslanzadeh, Solmaz, et al.
(författare)
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Biogas Production from N-Methylmorpholine-N-oxide (NMMO) Pretreated Forest Residues
- 2014
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Ingår i: Applied Biochemistry and Biotechnology. - : Humana Press, Inc.. - 0273-2289 .- 1559-0291. ; 172:6, s. 2998-3008
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Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic biomass represents a great potential for biogas production. However, a suitable pretreatment is needed to improve their digestibility. This study investigates the effects of an organic solvent, N-Methylmorpholine-N-oxide (NMMO) at temperatures of 120 and 90 °C, NMMO concentrations of 75 and 85 % and treatment times of 3 and 15 h on the methane yield. The long-term effects of the treatment were determined by a semicontinuous experiment. The best results were obtained using 75 % NMMO at 120 °C for 15 h, resulting in 141 % increase in the methane production. These conditions led to a decrease by 9 % and an increase by 8 % in the lignin and in the carbohydrate content, respectively. During the continuous digestion experiments, a specific biogas production rate of 92 NmL/gVS/day was achieved while the corresponding rate from the untreated sample was 53 NmL/gVS/day. The operation conditions were set at 4.4 gVS/L/day organic loading rate (OLR) and hydraulic retention time (HRT) of 20 days in both cases. NMMO pretreatment has substantially improved the digestibility of forest residues. The present study shows the possibilities of this pretreatment method; however, an economic and technical assessment of its industrial use needs to be performed in the future.
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| 8. |
- Aslanzadeh, Solmaz, et al.
(författare)
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Pretreatment of straw fraction of manure for improved biogas production
- 2011
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Ingår i: BioResources. - 1930-2126. ; 6:4, s. 5193-5205
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Tidskriftsartikel (refereegranskat)abstract
- Pretreatment of straw separated from cattle and horse manure using N-methylmorpholine oxide (NMMO) was investigated. The pretreatment conditions were for 5 h and 15 h at 120 °C, and the effects were evaluated by batch digestion assays. Untreated cattle and horse manure, both mixed with straw, resulted in 0.250 and 0.279 Nm3 CH4/kgVS (volatile solids), respectively. Pretreatment with NMMO improved both the methane yield and the degradation rate of these substrates, and the effects were further amplified with more pretreatment time. Pretreatment for 15 h resulted in an increase of methane yield by 53% and 51% for cattle and horse manure, respectively. The specific rate constant, k0, was increased from 0.041 to 0.072 (d-1) for the cattle and from 0.071 to 0.086 (d-1) for the horse manure. Analysis of the pretreated straw shows that the structural lignin content decreased by approximately 10% for both samples and the carbohydrate content increased by 13% for the straw separated from the cattle and by 9% for that separated from the horse manure. The crystallinity of straw samples analyzed by FTIR show a decrease with increased time of NMMO pretreatment.
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| 9. |
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| 10. |
- Bátori, Veronika, 1980-, et al.
(författare)
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Anaerobic degradation of bioplastics: A review
- 2018
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X. ; 80, s. 406-413
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW), leading to renewableenergy production in the form of methane, is a preferable method for dealing with the increasing amountof waste. Food waste is separated at the source in many countries for anaerobic digestion. However, thepresence of plastic bags is a major challenge for such processes. This study investigated the anaerobicdegradability of different bioplastics, aiming at potential use as collecting bags for the OFMSW. Thechemical composition of the bioplastics and the microbial community structure in the AD processaffected the biodegradation of the bioplastics. Some biopolymers can be degraded at hydraulic retentiontimes usually applied at the biogas plants, such as poly(hydroxyalkanoate)s, starch, cellulose and pectin,so no possible contamination would occur. In the future, updated standardization of collecting bags forthe OFMSW will be required to meet the requirements of effective operation of a biogas plant.
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| 11. |
- Berglund Odhner, Peter, et al.
(författare)
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Biogas from lignocellulosic biomass
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Grontmij AB has cooperated with the University of Borås to evaluate the technological and economical possibilities for biogas production from substrates containing lignocellulose, such as forest residues, straw and paper. The state of knowledge regarding biogas production from cellulosic biomass has been summarized. The research in the field has been described, especially focusing on pretreatment methods and their results on increased gas yields. An investigation concerning commercially available pretreatment methods and the cost of these technologies has been performed. An economic evaluation of biogas production from lignocellulosic materials has provided answers to questions regarding the profitability of these processes. Pretreatment with steam explosion was economically evaluated for three feedstocks – wood, straw and paper – and a combination of steam explosion and addition of NaOH for paper. The presented costs pertain to costs for the pretreatment step as it, in this study, was assumed that the pretreatment would be added to an existing plant and the lignocellulosic substrates would be part of a co-digestion process. The results of the investigation indicate that it is difficult to provide a positive net result when comparing the cost of pretreatment versus the gas yield (value) for two of the feedstocks – forest residues and straw. This is mainly due to the high cost of the raw material. For forest residues the steam pretreatment cost exceeded the gas yield by over 50 %, mainly due to the high cost of the raw material. For straw, the production cost was similar to the value of the gas. Paper showed the best economic result. The gas yield (value) for paper exceeded the pretreatment cost by 15 %, which makes it interesting to study paper further.
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| 12. |
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| 13. |
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| 14. |
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Factors influencing volatile fatty acids production from food wastes via anaerobic digestion
- 2020
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Ingår i: Bioengineered. - : Informa UK Limited. - 2165-5979 .- 2165-5987. ; 11:1, s. 39-52
-
Tidskriftsartikel (refereegranskat)abstract
- Volatile fatty acids (VFAs) are intermediate products in anaerobic digestion. The effect of substrate loading or inoculum to substrate ratio (ISR), the addition of methanogen inhibitor, O2 presence, control the reactor's pH, and inoculum adaptation on the VFAs production from food waste through acidogenesis process was investigated in this study. Addition of 2-bromoethane sulfonic (BES) as methanogen inhibitor suppressed VFA consumption by methanogens at ISR 1:1. At higher substrate loading (ISR 1:3), methane production can be suppressed even without the addition of BES. However, at high substrate loading, controlling the pH during acidogenesis is important to achieve high VFAs yield. Acclimatization of inoculum is also one of the strategies to achieve high VFA yield. The highest VFAs yield obtained in this work was 0.8 g VFA/g VS added at ISR 1:3, controlled pH at 6, with the presence of initial O2 (headspace unflushed).
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| 15. |
- Foereid, B., et al.
(författare)
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Effect of anaerobic digestion of manure before application to soil – benefor nitrogen utilisation?
- 2021
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Ingår i: International Journal of Recycling of Organic Waste in Agriculture. - : Islamic Azad University. - 2195-3228 .- 2251-7715. ; 10:1, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Anaerobic digestion produces renewable energy, biogas, from organic residues, but also digestate, a valuable organic fertiliser. Previous studies have indicated that digestate contains ample plant available nitrogen (N), but there are also concerns about greenhouse gas (GHG) emissions after application of digestates to soil. The aim of this study was to compare digestate and undigested feedstock for fertiliser effect as well as greenhouse gas emissions during the next season. Method Digestate and its feedstock, manure, were compared as N fertilisers for wheat. Mixing digestate with biochar before application was also tested. After harvest, soil samples were frozen and dried. Then GHG emissions immediately after a re-wetting of dry soil and after thawing of frozen soil were measured to determine emissions after a non-growing season (dry or cold). Results All N in digestate was plant available, while there was no significant N fertiliser effect of the undigested manure. N2 O emissions were higher after a dry season than after freezing, but the undigested manure showed higher emissions during thawing than those detected during thawing of soils from any of the other treatments. Conclusion Anaerobic digestion makes N available to plants, and when residues with much N that is not plant available the first season are used, the risk of N2 O emission next spring is high. © 2021, Islamic Azad University. All rights reserved.
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| 16. |
- Forgács, Gergely, 1983, et al.
(författare)
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Metahne Production from citrus waste: Process development and cost estimation
- 2012
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Ingår i: Journal of Chemical Technology and Biotechnology. - : Wiley. - 1097-4660 .- 0268-2575. ; 87:2, s. 250-255
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Tidskriftsartikel (refereegranskat)abstract
- AbstractLignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The cost of ethanol production from lignocellulosic materials is relatively high based on current technologies, and the main challenges are the low yield and high cost of the hydrolysis process. Considerable research efforts have been made to improve the hydrolysis of lignocellulosic materials. Pretreatment of lignocellulosic materials to remove lignin and hemicellulose can significantly enhance the hydrolysis of cellulose. Optimization of the cellulase enzymes and the enzyme loading can also improve the hydrolysis. Simultaneous saccharification and fermentation effectively removes glucose, which is an inhibitor to cellulase activity, thus increasing the yield and rate of cellulose hydrolysis.
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| 17. |
- Forgács, Gergely, et al.
(författare)
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Methane production from feather waste pretreated with Ca(OH)2: Process development and economical analysis
- 2014
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Ingår i: Waste and Biomass Valorization. - : Springer Netherlands. - 1877-2641 .- 1877-265X. ; 5:1, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the industrial application of feather waste as a substrate for anaerobic digestion. Feather was pretreated with 0–0.2 Ca(OH)2 g/g TSfeather (total solids of feathers) for 30–120 min at 100–120 °C, in order to increase the digestibility, and to enhance the methane yield in a subsequent digestion at 55 °C. Based on the results of the batch digestion, an industrial process was developed, which can achieve 0.40 Nm3/kg VSfeather (volatile solids of feathers) methane yield from the pretreated feathers, while it fulfills the animal by-product hygenization requirements as well. This base case of the industrial pretreatment process was designed using SuperPro Designer® for utilizing 2,500 tons of feathers per year, which is the waste stream from an average slaughterhouse with a capacity of 60,000 broilers per day. The production cost of the methane is estimated to be 0.475 EUR/Nm3, while the investments on the pretreatment unit requires 0.97 million EUR as total capital investment, and 0.25 million EUR/year for operating cost. However, the process is sensitive to the plant capacity. Changing the plant capacity from 625 to 10,000 tons of feather per year, results in reducing the biogas production cost from 1.177 to 0.203 EUR/Nm3. In addition, sensitivity analysis was performed on the base case to investigate the effect of the value of the incoming feather on the overall process profitability. The results showed that the proposed investment could be considered as being financially viable in the case of production of upgraded biomethane even without the current gate fee system.
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| 18. |
- 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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| 19. |
- Habagil, Moshe, et al.
(författare)
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Biogas Production from Food Residues-The Role of Trace Metals and Co-Digestion with Primary Sludge
- 2020
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Ingår i: Environments. - : MDPI. - 2076-3298. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- The majority of municipal Wastewater Treatment Plants (WWTPs) in Sweden produce biogas from sewage sludge. In order to increase the methane production, co-digestion of internal sludge with Organic Fraction of Municipal Solid Waste (OFMSW) might be feasible in the future. The objective of this study was therefore to find a beneficial solution for the utilization of OFMSW at the WWTP in Varberg, Sweden. The effects of co-digesting primary sludge (PS) and OFMSW collected in the municipality, in different mixing ratios, were investigated by semi-continuous anaerobic digestion assays. Furthermore, the effects of the addition of a commercial trace elements mixture solution (CTES), available on the market in Sweden, were also examined. Co-digestion of OFMSW and PS resulted in specific methane yields of 404, 392, and 375 NmL CH4/g volatile solids (VS), obtained during semi-continuous operations of 301, 357 and 385 days, for the reactors fed with OMFSW:PS ratio of 4:1, 3:1, and 1:1, and at maximum organic loading rates (OLRs) achieved of 4.0, 4.0 and 5.0 gVS/L/d, respectively. Furthermore, mono-digestion of OFMSW failed already at OLR of 1.0 gVS/L/d, however, an OLR of 4.0 gVS/L/d could be achieved with addition of 14 mu L/g VS Commercial Trace Element Solutions (CTES) leading to 363 mL CH4/g VS methane production. These experiments were running during 411 days. Hence, higher process efficiency was obtained when using co-digestion of OFMSW and PS compared to that of OFMSW in mono-digestion. Co-digestion is a more feasible option where a balanced Carbon/Nitrogen (C/N) ratio and nutrient supply can be maintained.
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| 20. |
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| 21. |
- Holliger, Christof, et al.
(författare)
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Towards a standardization of biomethane potential tests
- 2016
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 74:11, s. 2515-2522
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Tidskriftsartikel (refereegranskat)abstract
- Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. A workshop was held in June 2015 in Leysin Switzerland to agree on common solutions to the conundrum of inconsistent BMP test results. A discussion covers actions and criteria that are considered compulsory ito accept and validate a BMP test result; and recommendations concerning the inoculum substrate test setup and data analysis and reporting ito obtain test results that can be validated and reproduced.
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| 22. |
- Jansson, Anette, et al.
(författare)
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Dry Anaerobic Digestion of Food and Paper Industry Wastes at Different Solid Contents
- 2019
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Ingår i: Fermentation. - : MDPI. - 2311-5637. ; 5:2, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- A large volume of food is being wasted every year, while the pulp and paper industry also generate a large amount of solid wastes on a daily basis, causing environmental challenges around the world. Dry anaerobic digestion (AD) of these solid wastes is a cost-effective method for proper management. However, dry digestion of these waste streams has been restricted due to their complex structure, the presence of possible inhibitors and inappropriate operating conditions. In light of this fact, dry digestion of food waste (FW) and paper wastes (PW) was conducted at different total solid (TS) concentrations of reactor mixtures of 14%, 16%, 18% and 20% TS, corresponding to substrate to inoculum (S/I) ratio of 0.5 and 1; investigating the optimum operating conditions for effective dry digestion of these complex wastes. The highest methane yields of 402 NmlCH(4)/gVS and 229 NmlCH(4)/gVS were obtained from digestion of FW and PW, respectively at 14%TS corresponding to an S/I ratio of 0.5. Increasing the S/I ratio from 0.5 to 1 and thereby having a TS content of 20% in the reactor mixtures was unfavorable to the digestion of both substrates.
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| 23. |
- Jansson, Anette, et al.
(författare)
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Effect of organic compounds on dry anaerobic digestion of food and paper industry wastes
- 2020
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Ingår i: Bioengineered. - : Taylor & Francis Group. - 2165-5979 .- 2165-5987. ; 11:1, s. 502-509
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Tidskriftsartikel (refereegranskat)abstract
- Effects of antimicrobial compounds on dry anaerobic digestion (dry-AD) processes were investigated. Four compounds with known inhibition effects on traditional wet digestion, i.e. car-3-ene, hexanal, 1-octanol and phenol were selected and investigated at concentrations of 0.005%, 0.05% and 0.5%. Food waste (FW) and Paper waste (PW) were used as model substrates, all assays were running with the substrate to inoculum ratio of 1:1 (VS basis) corresponding to 15% TS in reactors. Generally, increasing concentrations of inhibitors resulted in decreasing methane yields with a few exceptions; in all these specific cases, long, lag phase periods (60 days) were observed. These adaptation periods made possible for the microbial systems to acclimatize to otherwise not preferred conditions leading to higher methane yields. Comparing the effects of the four different groups, phenols had the highest inhibitory effects, with no methane production at the highest amount added, while the lowest effects were obtained in cases of car-3-ene. Furthermore, the results showed that adding inhibitors up to a certain concentrations can repair the balance in AD process, slowing down the degradation steps, hence making it possible for the methanogens to produce a higher amount of methane. This phenomenon was not observed in case of PW, which is already a slow degradable substrate in its nature.
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| 24. |
- Kabir, Maryam M., et al.
(författare)
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6 Biogas from Wastes
- 2015
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Ingår i: Resource Recovery to Approach Zero Municipal Waste. - : CRC Press. - 9781138892750
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Bokkapitel (refereegranskat)
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| 25. |
- Kabir, Maryam M., et al.
(författare)
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Biogas from Lignocellulosic Materials
- 2015
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Ingår i: Lignocellulose-Based Bioproducts. - Switzerland : Springer. - 3319140329 ; , s. 207-251
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 26. |
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| 27. |
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| 28. |
- Kabir, Maryam M, et al.
(författare)
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Dry anaerobic digestion of lignocellulosic and protein residues
- 2015
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Ingår i: Biofuel Research Journal. ; 2:4, s. 309-316
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Tidskriftsartikel (refereegranskat)abstract
- Utilisation of wheat straw and wool textile waste in dry anaerobic digestion (AD) process was investigated. Dry-AD of the individual substrates as well as co-digestion of those were evaluated using different total solid (TS) contents ranging between 6 to 30%. Additionally, the effects of the addition of nutrients and cellulose- or protein-degrading enzymes on the performance of the AD process were also investigated. Dry-AD of the wheat straw resulted in methane yields of 0.081 – 0.200 Nm3CH4/kgVS with the lowest and highest values obtained at 30 and 21% TS, respectively. The addition of the cellulolytic enzymes could significantly increase the yield in the reactor containing 13% TS (0.231 Nm3CH4/kg VS). Likewise, degradation of wool textile waste was enhanced significantly at TS of 13% with the addition of the protein-degrading enzyme (0.131 Nm3CH4/kg VS). Furthermore, the co-digestion of these two substrates showed higher methane yields compared with the methane potentials calculated for the individual fractions at all the investigated TS contents due to synergetic effects and better nutritional balance.
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| 29. |
- Kabir, Maryam M, et al.
(författare)
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Effect of the N-methylmorpholine-N-oxide (NMMO) pretreatment on anaerobic digestion of forest residues
- 2013
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Ingår i: BioResources. - : North Carolina State University: College of Natural Resources. - 1930-2126. ; 8:4, s. 5409-5423
-
Tidskriftsartikel (refereegranskat)abstract
- Pretreatment of forest residues using N - methylmorpholine - N - oxide (NMMO or NMO) prior to anaer obic digestion was investigated , where the effects of particle size, NMMO concentration , and pretreatment time were the primary focus. The pretreatments were carried out on forest residues; with different particle size s of 2, 4 and 8 mm , at 120 °C for 3, 7 , and 15 h in two different modes of NMMO - treatment : dissolution by 85% NMMO and swelling without dissolution using 75% NMMO solution in water . The pretreatment process led to minor changes in the composition of the forest residues . The best improvement in methane yield of the forest residues was achieved by pretreatment using 85% NMMO for 15 h at 120 °C. This treatment resulted in 0.1 7 Nm 3 /kg VS methane yield , which corresponds to 83 % of the expected theoretical yield of carbohydrates present in the material. Additionally, the accumulated methane yield and the rate of the methane production were highly affected by the amounts of remaining NMMO when it was not well separated during the washing and filtration step s after the treatment. The p resence o f concentrations even as low as 0.008 % NMMO resulted in a decrease in the final methan e yield by 45% , while the presence of 1% of this solvent in the digester completely terminated the anaerobic digestion process.
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| 30. |
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| 31. |
- Kabir, Maryam M., et al.
(författare)
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Enhanced methane production from wool textile residues by thermal and enzymatic pretreatment
- 2013
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113 .- 1873-3298. ; 48:4, s. 575-580
-
Tidskriftsartikel (refereegranskat)abstract
- Methane production from two types of wool textile wastes (TW1 and TW2) was investigated. To improve the digestibility of these textiles, different pretreatments were applied, and comprised thermal treatment (at 120 C for 10 min), enzymatic hydrolysis (using an alkaline endopeptidase at different levels of enzymatic loading, at 55 C for 0, 2, and 8 h), and a combination of these two treatments. Soluble protein concentration and sCOD (soluble chemical oxygen demand) were measured to evaluate the effectivity of the different pretreatment conditions to degrade wool keratin. The sCOD as well as the soluble protein content had increased in both textile samples in comparison to untreated samples, as a response to the different pretreatments indicating breakdown of the wool keratin structure.The combined treatments and the thermal treatments were further evaluated by anaerobic batch digestion assays at 55 C. Combined thermal and enzymatic treatment of TW1 and TW2 resulted in methane productions of 0.43 N m(3)/kg VS and 0.27 N m(3)/kg VS, i.e., 20 and 10 times higher yields, respectively, than that gained from untreated samples. The application of thermal treatment by itself was less effective and resulted in increasing the methane production by 10-fold for TW1 and showing no significant improvement for TW2.
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| 32. |
- Kabir, Maryam M., et al.
(författare)
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Pretreatment of wool based textile wastes for enhanced biogas production
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two different wool based textile wastes (TW1 and TW2) have been subjected for biogas production. TW1 was composed of 70% wool and 30% polyamide (PA), while TW2 consisted of 70% wool, 18% PA and 12% kermel (protective polyamide-imide fibre). Two pre-treatments: thermal treatment, enzymatic treatment and combinations of these two were performed to enhance the methane yield. Determining the soluble protein concentrations in the treated samples showed that the additional thermal treatment and the enzyme concentration had significant positive effect on the degradation of wool. Samples treated with thermal and combination treatments were therefore selected for anaerobic batch digestion assays. The best results were obtained after combination treatments resulting in methane yields of 0.33-0.43 Nm3/kg VS, and 0.21-0.26 Nm3/kg VS, for TW1 and TW2, respectively, while only 0.21 and 0.05 Nm3/kg VS methane production was measured after the thermal treatment. The methane yields of untreated samples were close to zero.
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| 33. |
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| 34. |
- Karimi, Keikhosro, et al.
(författare)
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Recent trends in acetone, butanol, and ethanol (ABE) production
- 2015
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Ingår i: Biofuel Research Journal. ; 2:4, s. 301-308
-
Tidskriftsartikel (refereegranskat)abstract
- Among the renewable fuels considered as a suitable substitute to petroleum-based gasoline, butanol has attracted a great deal of attention due to its unique properties. Acetone, butanol, and ethanol (ABE) can be produced biologically from different substrates, including sugars, starch, lignocelluloses, and algae. This process was among the very first biofuel production processes which was commercialized during the First World War. The present review paper discusses the different aspects of the ABE process and the recent progresses made. Moreover, the microorganisms and the biochemistry of the ABE fermentation as well as the feedstocks used are reviewed. Finally, the challenges faced such as low products concentration and products` inhibitory effects on the fermentation are explained and different possible solutions are presented and reviewed.
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| 35. |
- Kashi, Sima, et al.
(författare)
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Application of a mixture design to identify effects of susbtrates ratios and intractions on anaerobic digestion of municipal sludge, grease trapwaste, and meat processing waste
- 2017
-
Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 5:6, s. 6156-6164
-
Tidskriftsartikel (refereegranskat)abstract
- Anaerobic mono- and co-digestion of two municipal sludge wastes (A and C), grease trap waste (B), and meat processing waste (D) were investigated under mesophilic temperature conditions by biochemical methane potential (BMP) assays and kinetic modeling. Wastes ratios in the mixtures were systematically selected based on Simplex Lattice mixture design, and statistical analyses were performed to elucidate possible synergetic and antagonistic effects of wastes interactions on the kinetics and ultimate methane potentials of wastes co-digestion. The mixture of 1/8A + 1/8B + 1/8C + 5/8D (VS basis) showed the highest COD and VS removals of 35.0% and 33.8%, respectively. Substrates B and D with 980 and 641 mL/g-VS methane yields, respectively, had the highest BMP. However, with reaction rate constants of 0.047 and 0.070 d−1, their methane production was very slow. It was observed that diluting these organic-rich but complex substrates with readily soluble wastes (A and C) enhanced their biogas production rate markedly. Statistical analysis showed that the interactions among the substrates in co-digestion did not have a significant impact on the ultimate cumulative methane yields. Nevertheless, these interactions proved to have synergic and antagonistic effects on the reaction rates, leading to accelerated or hindered methane production rates. As a result, while the methane yield of wastes co-digestion could be predicted by proportional summation of methane yields obtained in mono-digestions of these waste fractions, such linear regressions were unable to provide a good estimation of the rate constants. Quadratic equations, however, were found to estimate the rate constants of the co-digestion process with good accuracy
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| 36. |
- Kumar, Rajeev, et al.
(författare)
-
Recent updates on lignocellulosic biomass derived ethanol-A review
- 2016
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Ingår i: Biofuel Research Journal. - 2292-8782. ; 3:1, s. 347-356
-
Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic (or cellulosic) biomass derived ethanol is the most promising near/long term fuel candidate. In addition, cellulosic biomass derived ethanol may serve a precursor to other fuels and chemicals that are currently derived from unsustainable sources and/or are proposed to be derived from cellulosic biomass. However, the processing cost for second generation ethanol is still high to make the process commercially profitable and replicable. In this review, recent trends in cellulosic biomass ethanol derived via biochemical route are reviewed with main focus on current research efforts that are being undertaken to realize high product yields/titers and bring the overall cost down.
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| 37. |
- Mirabdollah, A., et al.
(författare)
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Optimization of a protoplast transformation method for Bacillus Subtilis, Bacillus megaterium, and Bacillus Cereus by a plasmid pHIS1525.SplipA
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During the past years of gene cloning studies, Escherichia coli has always been a foremost host cell for exogenous genes expressions owing to its high level of protein production and excretion. However, problems relating to low level of extracellular production of some proteins specially the accumulation of cloned proteases within the cells have moved the attentions from E.coli to bacilli bacteria such as B. megaterium, B.subtilis, and B.cereus due to their secretion ability of many different enzymes. Bacillus megaterium is widely used for high-level expression of heterologous proteins with little or no degradation. Bacillus subtilis is a naturally competent host cell for uptake of exogenous DNA, resulting in attractive industrial applications. Bacillus cereus has sporulation capability which makes it suitable for several industrial uses. A conventional approach for transferring DNA into protoplasts or intact cells of bacillus bacteria is chemical transformation, using chemicals through chilling and then shock-heating of the suspension of cells to induce reversible permeabilization of the cell membrane to make it possible for the external DNA to enter into the cells. In most cloning experiments, the transformation with plasmid DNA is performed using Polyethylene glycol (PEG)-induced competence cells. In this study, a PEG-induced protoplast transformation protocol was developed for three different bacillus strains of Bacillus megaterium ATCC®14945, Bacillus Subtilis ATCC®6051, and Bacillus Cereus ATCC®14579. In all cases a plasmid pHIS1525.SPlipA, well working vector in B.megaterium, was applied. Protoplasts were formed in RHAF medium after treating the cells with lysozyme. Two factors, the incubation time and the lysozyme concentration have been found to play the most important role in effective protoplast formation. These two factors were further optimized in this study to elaborate a chemical transformation procedure which can possibly work for other bacillus strains as well. The optical density (A420) and the number of colony-forming units (CFUs) were determined to find the optimal conditions for each strain. The results indicate that PEG-induced protoplast transformation is a sufficient technique when using a plasmid pHIS1525.SPlipA in Bacillus genus.
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| 38. |
- Mirmohamadsadeghi, Safoora, et al.
(författare)
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Enhanced solid-state biogas production from lignocellulosic biomass by organosolv pretreatment
- 2014
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Ingår i: BioMed Research International. - : Hindawi Limited. - 2314-6133 .- 2314-6141. ; 2014
-
Tidskriftsartikel (refereegranskat)abstract
- Organosolv pretreatment was used to improve solid-state anaerobic digestion (SSAD) for methane production from three different lignocellulosic substrates (hardwood elm, softwood pine, and agricultural waste rice straw). Pretreatments were conducted at 150 and 180°C for 30 and 60 min using 75% ethanol solution as an organic solvent with addition of sulfuric acid as a catalyst. The statistical analyses showed that pretreatment temperature was the significant factor affecting methane production. Optimum temperature was 180°C for elmwood while it was 150°C for both pinewood and rice straw. Maximum methane production was 152.7, 93.7, and 71.4 liter per kg carbohydrates (CH), which showed up to 32, 73, and 84% enhancement for rice straw, elmwood, and pinewood, respectively, compared to those from the untreated substrates. An inverse relationship between the total methane yield and the lignin content of the substrates was observed. Kinetic analysis of the methane production showed that the process followed a first-order model for all untreated and pretreated lignocelluloses.
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| 39. |
- Mirmohamadsadeghi, Safoora, et al.
(författare)
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Improvement of Solid-State Biogas Production from Wood by Concentrated Phosphoric Acid Pretreatment
- 2016
-
Ingår i: BioResources. - : BioResources. - 1930-2126. ; 11:2, s. 3230-3243
-
Tidskriftsartikel (refereegranskat)abstract
- Cellulose Solvent-And organic Solvent-Based lignocellulose fractionation (COSLIF) has been repeatedly shown to be a Cost-Effective and promising process to modify the structure of different lignocelluloses. It has been repeatedly reported to improve enzymatic hydrolysis and ethanol production from different lignocelluloses. In this study, COSLIF was used to improve biomethane production from pine (softwood), poplar (soft hardwood), and berry (hard hardwood) via solid state anaerobic digestion (SSAD). Feed to inoculum (F/I) ratio, which plays a major role in SSAD, was set to 3, 4, and 5. After the pretreatment, 39, 33, and 24% higher methane yield from pine was achieved for F/I ratios of 3, 4, and 5, respectively. However, the methane yield from the hardwoods was not improved by the pretreatment, which was related to overloading of the digester. Compositional analysis showed considerable reduction in hemicellulose and lignin content by the pretreatment. Structural changes in the woods, before and after the pretreatment, were examined by X-Ray diffractometer and scanning electron microscopy. The results showed that the crystallinity of cellulose was decreased and accessible surface area was drastically increased by the pretreatment.
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| 40. |
- Momayez, Forough, et al.
(författare)
-
Efficient hydrolysis and ethanol production from rice straw by pretreatment with organic acids and effluent of biogas plant
- 2017
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 7:80, s. 50537-50545
-
Tidskriftsartikel (refereegranskat)abstract
- The effluent of biogas production plant was used for the pretreatment of rice straw for the improvement of ethanol production. In addition, the organic active ingredients of the effluent, i.e., acetic, butyric, lactic and propionic acids (1-4%), as well as water were employed for the pretreatment at 100 and 140 °C. The results indicated that pretreatment at 100 °C had no significant effect on the performance of subsequent enzymatic hydrolysis and ethanol production by simultaneous saccharification and fermentation (SSF). Among different types of organic acids presented in the effluent, lactic acid showed a better performance. The highest concentration of glucose and ethanol were achieved after 72 h enzymatic hydrolysis and SSF from the straw pretreated at 140 °C with 4% lactic acid. Applying the effluent for the straw pretreatment at 140 °C resulted in an increase in glucose and ethanol concentrations by 42.4 and 47.5%, respectively, compared to those from untreated samples. SEM, FTIR, BET, BJH, and compositional analyses were used to characterize the changes in the structure and composition of rice straw by the pretreatment. Changes in the straw swelling, cellulose crystallinity, pore size distribution, and composition were responsible for the acquired improvements.
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| 41. |
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| 42. |
- Nair, Ramkumar B, 1988-, et al.
(författare)
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Integrated Process for Ethanol, Biogas, and Edible Filamentous Fungi-Based Animal Feed Production from Dilute Phosphoric Acid-Pretreated Wheat Straw
- 2017
-
Ingår i: Applied Biochemistry and Biotechnology. - : Springer Science and Business Media LLC. - 0273-2289 .- 1559-0291. ; , s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- Integration of wheat straw for a biorefinery-based energy generation process by producing ethanol and biogas together with the production of high-protein fungal biomass (suitable for feed application) was the main focus of the present study. An edible ascomycete fungal strain Neurospora intermedia was used for the ethanol fermentation and subsequent biomass production from dilute phosphoric acid (0.7 to 1.2% w/v) pretreated wheat straw. At optimum pretreatment conditions, an ethanol yield of 84 to 90% of the theoretical maximum, based on glucan content of substrate straw, was observed from fungal fermentation post the enzymatic hydrolysis process. The biogas production from the pretreated straw slurry showed an improved methane yield potential up to 162% increase, as compared to that of the untreated straw. Additional biogas production, using the syrup, a waste stream obtained post the ethanol fermentation, resulted in a combined total energy output of 15.8 MJ/kg wheat straw. Moreover, using thin stillage (a waste stream from the first-generation wheat-based ethanol process) as a co-substrate to the biogas process resulted in an additional increase by about 14 to 27% in the total energy output as compared to using only wheat straw-based substrates. .[on SciFinder (R)]
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| 43. |
- Pagés Díaz, Jhosané, et al.
(författare)
-
A comparison of process performance during the anaerobic mono-and co-digestion of slaughter house waste through different operational modes
- 2017
-
Ingår i: Journal of Environmental Sciences(China). - : Elsevier BV. - 1001-0742 .- 1878-7320.
-
Tidskriftsartikel (refereegranskat)abstract
- The use of consecutive feeding was applied to investigate the response of the microbial biomass to a second addition of substrates in terms of biodegradation using batch tests as a promising alternative to predict the behavior of the process. Anaerobic digestion (AD) of the slaughterhouse waste (SB) and its co-digestion with manure (M), various crops (VC), and municipal solid waste were evaluated. The results were then correlated to previous findings obtained by the authors for similar mixtures in batch and semi-continuous operation modes. AD of the SB failed showing total inhibition after a second feeding. Co-digestion of the SB + M showed a significant improvement for all of the response variables investigated after the second feeding, while co-digestion of the SB + VC resulted in a decline in all of these response variables. Similar patterns were previously detected, during both the batch and the semi-continuous modes.
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| 44. |
- Pagés Díaz, Jhosané, et al.
(författare)
-
An approach to the codigestion process of solid slaughterhouse waste, manure, various crop and municipal solid waste
- 2011
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A codigestion process was evaluated when mixing different ratios of agro-industrial residues, i.e. slaughterhouse waste (SB); manure (M); various crop residues (VC); and municipal solid waste (MSW). Methane yield (YCH4) and specific methanogenic activity (SMA) were determined by anaerobic batch digestion of the different substrates and substrate mixtures. The performance of the codigestion was also evaluated by kinetics (k0) based on the methane production rate. The investigated residues and their mixtures were found to have high potentials for the production of biogas. The codigestion process showed to be a feasible option with positive influence in both energy production and environmental care. Taking into account significance differences, the best results were obtained with a mixture ratio of 1:3:4:0.5 based on the w/w content of SB, M, VC, and MSW, respectively, which showed a proper combination of high values in YCH4, SMA and k0 during the anaerobic process. The effect of temperature suggested that thermophilic conditions are suitable to treat these residues. Response variables were severely affected by mesophilic conditions, diminishing in at least 45% of the thermophilic value when a mixture ratio of 2:3:3:0 based on the w/w content of SB:M:VC:MSW was selected. It is suggested to study the influence of individual component within the mixture for every response variable. Consecutive feedings are also suggested in order to step forward to continuous process and evaluate possible inhibitions.
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| 45. |
- Pagés Díaz, Jhosané, et al.
(författare)
-
Anaerobic co-digestion of solid slaughterhouse wastes with agro-residues : Synergistic and antagonistic interactions determined in batch digestion assays
- 2014
-
Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 245, s. 89-98
-
Tidskriftsartikel (refereegranskat)abstract
- Different mixture ratios of solid cattle slaughterhouse wastes (SB), manure (M), various crops (VC), and municipal solid wastes (MSW) were investigated for biogas production. The objective was to explore possible significant synergistic effects obtained from the combination of these different substrates. The performance of the process was assessed in thermophilic anaerobic batch co-digestion assays, using a four factor mixture design and methane yield (Y-CH4) and specific methane production rate (r(scH4)) as response variables. The highest methane yield, 655 NmL CH4/g VS was obtained when equal parts (ww) of SB, M, VC, and MSW were combined, while the combination of SB, M, and MSW resulted in the highest specific methane production rate (43 NmL CH4/g VS/d). A mixture design model was fitted to data in order to appraise synergistic and antagonistic interactions. Mixing all four substrates resulted in a 31% increase of the expected yield which was calculated from the methane potential of the individual fractions, clearly demonstrating a synergistic effect due to more balanced nutrient composition enhancing the anaerobic digestion process. However, no significant antagonistic effects were observed. In order to maximize both response variables simultaneously, a response surface method was employed to establish the optimal combination of substrate mixtures. The statistical results and analysis of the biological process gave a coherent picture of the results. (C) 2014 Elsevier B.V. All rights reserved.
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| 46. |
- Pagés-Díaz, J., et al.
(författare)
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Co-digestion of bovine slaughterhouse wastes, cow manure, various crops and municipal solid waste at thermophilic conditions : a comparison with specific case running at mesophilic conditions
- 2013
-
Ingår i: Water Science and Technology. - : I W A Publishing. - 0273-1223 .- 1996-9732. ; 67:5, s. 989-995
-
Tidskriftsartikel (refereegranskat)abstract
- A co-digestion process was evaluated when mixing different ratios of agro-industrial residues, i.e. bovine slaughterhouse waste (SB); cow manure (M); various crop residues (VC); and municipal solid waste (MSW) by anaerobic batch digestion under thermophilic conditions (55 °C). A selected study case at mesophilic condition (37 °C) was also investigated. The performance of the co-digestion was evaluated by kinetics (k(0)). The best kinetic results were obtained under thermophilic operation when a mixture of 22% w/w SB, 22% w/w M, 45% w/w VC and 11% w/w MSW was co-digested, which showed a proper combination of high values in r(s)CH(4) and k(0) (0.066 Nm(3)CH(4)/kgVS*d, 0.336 d(-1)) during the anaerobic process. The effect of temperature on methane yield (Y(CH4)), specific methane rate (r(s)CH(4)) and k(0) was also analyzed for a specific study case; there a mixture of 25% w/w of SB, 37.5% w/w of M, 37.5% of VC and 0% of MSW was used. Response variables were severely affected by mesophilic conditions, diminishing to at least 45% of the thermophilic values obtained for a similar mixture. The effect of temperature suggested that thermophilic conditions are suitable to treat these residues.
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| 47. |
- Pagés Díaz, Jhosané, et al.
(författare)
-
Co-digestion of different waste mixtures from agro-industrial activities : Kinetic evaluation and synergetic effects
- 2011
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 102:23, s. 10834-10840
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Several wastes from agro-industrial activities were mixed in different ratios to evaluate the co-digestion process. Methane yield (YCH4), specific methanogenic activity (SMA) and a kinetic parameter (k0) were determined. A second feeding was also performed to examine the recovery of bacterial activity after exhaustion. Mixture ratios of 1:1:1:1 and 1:3:4:0.5 (w/w) showed the best performance, with YCH4 of 664; 582 NmL CH4/gVSsubstrate, as well as SMA of 0.12; 0.13 gCODNmLCH4/gVSinoculum/d, respectively, during the digestion of the first feed. It was possible to relate synergetic effects with enhancement in YCH4 by up to 43%, compared with values calculated from YCH4 of the individual substrates. All batches started up the biogas production after an exhaustion period, when a second feed was added. However, long lag phases (up to 21 days) were observed due to stressed conditions caused by the substrate limitation prior to the second feed.
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| 48. |
- Pages-Diaz, J., et al.
(författare)
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Semi-continuous co-digestion of solid cattle slaughterhouse wastes with other waste streams: Interactions within the mixtures and methanogenic community structure
- 2015
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 273, s. 28-36
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of the anaerobic co-digestion process is strongly related to the characteristics of the substrates utilized. In this work, the impact of mixture interactions, i.e., synergy and antagonism, previously observed in batch operation mode were evaluated under semi-continuous co-digestion of slaughterhouse waste (SB) and its different combinations with manure (M), various crops (VC), and municipal solid waste (MSW). The effects on the process performance and the microbial community structure were investigated. The digestion of SB failed at an OLR of 0.9 gVS L-1 d(-1). However, stable performance with higher loadings was observed for mixtures that displayed synergy obtained earlier in the batch mode (i.e., SB + M, SB + VC + MSW). Bacterial and Archaeal groups increased for the SB + M and SB + VC + MSW, compared with the digestion of SB alone and that for SB + VC. The combination that showed antagonistic effects (SB + VC) resulted in unstable operation and poor representation of methanogens. It was proved that synergetic or antagonistic effects observed in batch mode due to the different mixture compositions could be correlated to process performance, as well as the development of the microbial community structure during semi-continuous operation.
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| 49. |
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| 50. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
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Volatile Fatty Acids (VFAs) Generated by Anaerobic Digestion Serve as Feedstock for Freshwater and Marine Oleaginous Microorganisms to Produce Biodiesel and Added-Value Compounds
- 2021
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Given an increasing focus on environmental sustainability, microbial oils have been suggested as an alternative to petroleum-based products. However, microbial oil production relies on the use of costly sugar-based feedstocks. Substrate limitation, elevated costs, and risk of contamination have sparked the search for alternatives to sugar-based platforms. Volatile fatty acids are generated during anaerobic digestion of organic waste and are considered a promising substrate for microbial oil production. In the present study, two freshwater and one marine microalga along with two thraustochytrids were evaluated for their potential to produce lipids when cultivated on volatile fatty acids generated from food waste via anaerobic digestion using a membrane bioreactor. Freshwater microalgae Auxenochlorella protothecoides and Chlorella sorokiniana synthesized lipids rich in palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), and linoleic acid (C18:2). This composition corresponds to that of soybean and jatropha oils, which are used as biodiesel feedstock. Production of added-value polyunsaturated fatty acids (PUFA) mainly omega-3 fatty acids was examined in three different marine strains: Aurantiochytrium sp. T66, Schizochytrium limacinum SR21, and Crypthecodinium cohnii. Only Aurantiochytrium sp. T66 seemed promising, generating 43.19% docosahexaenoic acid (DHA) and 13.56% docosapentaenoic acid (DPA) in total lipids. In summary, we show that A. protothecoides, C. sorokiniana, and Aurantiochytrium sp. T66 can be used for microbial oil production from food waste material.
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