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  • 1. Alinezhad, S.
    et al.
    Mirabdollah, A.
    Forgács, Gergely
    University of Borås, School of Engineering.
    Feuk-Lagerstedt, Elisabeth
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    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 production2009Conference paper (Other academic)
    Abstract [en]

    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.

  • 2. Andreas, Billy
    et al.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Cahyari, Khamdan
    Setiadi, Tjandra
    Effects of Acid: Pretreatment of Inoculums and Substrate Concentration for Batch Thermophilic Biohydrogen Production from Starch - Rich Synthetic Wastewater2011In: lntemational Symposium on Southeast Asian Water Environment Part 1, 2011Conference paper (Refereed)
    Abstract [en]

    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.

  • 3.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Berg, Andreas
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Biogas Production from N-Methylmorpholine-N-oxide (NMMO) Pretreated Forest Residues2014In: Applied Biochemistry and Biotechnology, ISSN 0273-2289, E-ISSN 1559-0291, Vol. 172, no 6, p. 2998-3008Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pretreatment of straw fraction of manure for improved biogas production2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 4, p. 5193-5205Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pretreatment of straw fraction of manure for improved biogas production2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 4, p. 5193-5205Article in journal (Refereed)
  • 6. Berglund Odhner, Peter
    et al.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Kabir, Maryam M.
    University of Borås, School of Engineering.
    Shabbauer, Anna
    Biogas from lignocellulosic biomass2012Report (Other academic)
    Abstract [en]

    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.

  • 7. Borges, Marisa
    et al.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Towards zero waste: a comparative study on solid waste management between Curitiba in Brazil and Borås in Sweden2014Conference paper (Refereed)
  • 8. Carillo-Nieves, Danay
    et al.
    Zumalacárregui-de Cárdenas, Lourdes
    Franco-Rico, Rafael
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kinetic of biogas production from oil palm empty fruit bunches2014In: Dyna, ISSN 0012-7353, Vol. 81, no 187, p. 96-101Article in journal (Refereed)
  • 9. Carrillo Nieves, Danay
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Sárvári Horvátha, Ilona
    University of Borås, School of Engineering.
    Improvement of biogas production from oil palm empty fruit bunches (OPEFB)2011In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 34, no 1, p. 1097-1101Article in journal (Refereed)
    Abstract [en]

    Oil palm empty fruit bunches (OPEFB), a waste lignocellulosic material, which is the main byproduct of vegetable oil production industries in Indonesia and Malaysia, was utilized as a source for biogas production. Pretreatments using NaOH as well as phosphoric acid were investigated to improve the biogas production. Clear positive effects of the pretreatments on the yield of methane were observed. The best improvement was achieved when 8% NaOH for 60 min was used for the pretreatment, which resulted in 100% improvement in the yield of methane production. In addition, treatment with phosphoric acid resulted in 40% improvement in the methane yield compared with that of the untreated material. The results showed that the carbohydrate content of OPEFB could be efficiently converted to methane under the anaerobic digestion process. 97% of the theoretical value of methane production was achieved after the pretreatment with NaOH for 60 min. Moreover, the initial rate of methane production was also increased by more than 85% after the treatment with NaOH compared with that of the untreated OPEFB.

  • 10.
    Forgacs, G.
    et al.
    University of Borås, School of Engineering.
    Lundin, M.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pretreatment of chicken feather waste for improved biogas production2013In: Applied Biochemistry and Biotechnology, ISSN 0273-2289, E-ISSN 1559-0291, Vol. 169, no 7, p. 2016-2028Article in journal (Refereed)
    Abstract [en]

    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.

  • 11.
    Forgács, Gergely
    et al.
    University of Borås, School of Engineering.
    Alinezhad, Saeid
    Mirabdollah, Amir
    Feuk-Legerstedt, Elisabeth
    University of Borås, School of Engineering.
    Sávári Horváth, Ilona
    University of Borås, School of Engineering.
    Biological treatment of chicken feather waste for improved biogas production2011In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 23, no 10, p. 1747-1753Article in journal (Refereed)
    Abstract [en]

    A two-stage system was developed which combines the biological degradation of keratin-rich waste with the production of biogas. Chicken feather waste was treated biologically with a recombinant Bacillus megaterium strain showing keratinase activity prior to biogas production. Chopped, autoclaved chicken feathers (4%, W/V) were completely degraded, resulting in a yellowish fermentation broth with a level of 0.51 mg/mL soluble proteins after 8 days of cultivation of the recombinant strain. During the subsequent anaerobic batch digestion experiments, methane production of 0.35 Nm3/kg dry feathers (i.e., 0.4 Nm3/kg volatile solids of feathers), corresponding to 80% of the theoretical value on proteins, was achieved from the feather hydrolyzates, independently of the pre-hydrolysis time period of 1, 2 or 8 days. Cultivation with a native keratinase producing strain, Bacillus licheniformis resulted in only 0.25 mg/mL soluble proteins in the feather hydrolyzate, which then was digested achieving a maximum accumulated methane production of 0.31 Nm3/kg dry feathers. Feather hydrolyzates treated with the wild type B. megaterium produced 0.21 Nm3 CH4/kg dry feathers as maximum yield.

  • 12.
    Forgács, Gergely
    et al.
    University of Borås, School of Engineering.
    Niklasson, Claes
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    J. Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Methane Production from Feather Waste Pretreated2014In: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, Vol. 5, no 1, p. 65-73Article in journal (Refereed)
    Abstract [en]

    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.

  • 13.
    Forgács, Gergely
    et al.
    University of Borås, School of Engineering.
    Pourbafrani, Mohammad
    Niklasson, Claes
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Horváth Sárvari, Ilona
    University of Borås, School of Engineering.
    Methane production from citrus wastes: process development and cost estimation2011In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 87, no 2, p. 250-255Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Because of its extreme toxicity for microorganisms, the limonene content of citrus wastes (CWs) has been a major obstacle to the conversion of CWs to biofuels. The main objective of this study was to develop a new process for the utilization of CWs that can be economically feasible when the supply of CW is low. RESULTS: Steam explosion pre-treatment was applied to improve the anaerobic digestibility of CWs, resulting in a decrease of initial limonene concentration by 94.3%. A methane potential of 0.537 ± 0.001 m3 kg−1 VS (volatile solids) was obtained during the following batch digestion of treated CWs, corresponding to an increase of 426% compared with that of the untreated samples. Long-term effects of the treatment were further investigated by a semi-continuous co-digestion process. A methane production of 0.555 ± 0.0159 m3 CH4 kg−1 VS day−1 was achieved when treated CWs (corresponding to 30% of the VS load) were co-digested with municipal solid waste. CONCLUSION: The process developed can easily be applied to an existing biogas plant. The equipment cost for this process is estimated to be one million USD when utilizing 10 000 tons CWs year−1. 8.4 L limonene and 107.4 m3 methane can be produced per ton of fresh citrus wastes in this manner.

  • 14. Hashemi, Seyed Sajad
    et al.
    Karimi, Keikhosro
    Nosratpour, Mohammad Javad
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Efficient Biogas and Ethanol Production from Safflower Straw Using Sodium Carbonate Pretreatment2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 12, p. 10592-10601Article in journal (Refereed)
  • 15. Holliger, Christof
    et al.
    Alves, Madalena
    Andrade, Diana
    Angelidaki, Irini
    Astals, Sergi
    Baier, Urs
    Bougrier, Claire
    Buffière, Pierre
    Carballa, Marta
    de Wilde, Vinnie
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Towards a standardization of biomethane potential tests2016In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 74, no 11, p. 2515-2522Article in journal (Refereed)
    Abstract [en]

    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.

  • 16.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Aslanzadeh, Solmaz
    University of Borås, School of Engineering.
    Teghammar, Anna
    University of Borås, School of Engineering.
    del Pilar Castillo, Maria
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Biogas production from lignocelluloses by N-methylmorpholine-N-oxide (NMMO) pretreatment: Achievements and Challenges2014Conference paper (Other academic)
  • 17.
    Kabir, Maryam M
    et al.
    University of Borås, School of Engineering.
    del Pilar Castillo, Maria
    Taherzadeh, Mohammad. J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Effect of the N-methylmorpholine-N-oxide (NMMO) pretreatment on anaerobic digestion of forest residues2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 4, p. 5409-5423Article in journal (Refereed)
    Abstract [en]

    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.

  • 18. Kabir, Maryam M.
    et al.
    Forgács, Gergely
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Biogas from Lignocellulosic Materials2015In: Lignocellulose-Based Bioproducts, Switzerland: Springer, 2015, p. 207-251Chapter in book (Other academic)
  • 19.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Forgács, Gergely
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Biogas from lignocellulosic materials2015In: Lignocellulose-Based Bioproducts, Switzerland: Springer international publishing , 2015, p. 207-251Chapter in book (Other academic)
  • 20.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Forgács, Gergely
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pretreatment of wool based textile wastes for enhanced biogas production2012Conference paper (Other academic)
    Abstract [en]

    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.

  • 21.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Forgácsa, Gergely
    University of Borås, School of Engineering. Chalmers University of Technology.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Enhanced methane production from wool textile residues by thermal and enzymatic pretreatment2013In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 48, no 4, p. 575-580Article in journal (Refereed)
    Abstract [en]

    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 m3/kg VS and 0.27 N m3/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.

  • 22.
    Kabir, Maryam M.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajendran, K.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, M.J.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, I.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Experimental and economical evaluation of bioconversion of forest residues to biogas using organosolv pretreatment2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 178, p. 201-8Article in journal (Refereed)
    Abstract [en]

    The methane potential of forest residues was compared after applying organic solvent, i.e., acetic acid, ethanol, and methanol pretreatments using batch anaerobic digestion (AD). The pretreatments were performed at 190 °C with 50% (V/V) organic solvent for 60 min. The accumulated methane yields after 40 days of AD from pretreated forest residues were between 0.23 and 0.34 m3 CH4/kg VS, which shows a significant improvement compared to 0.05 m3 CH4/kg VS, from untreated forest residues. These improvements count up to 50% increase in the methane yields from the pretreated substrates based on expected theoretical yield from carbohydrates. Among the organic solvents, pretreatments with acetic acid and ethanol led to highest methane yields, i.e., over 0.30 m3 CH4/kg VS. However, techno-economical evaluation showed, pretreatment with methanol was more viable financially. The capital investments of the plant operating 20,000 tons of forest residues varied between 56 and 60 million USD, which could be recovered in less than 8 years of operation.

  • 23.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Enhanced biogas production from forest residues by NMMO pretreatment2013Conference paper (Refereed)
  • 24.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Biogas production from lignocelluloses by N-methylmorpholine-N-oxide (NMMO) pretreatment: Effect of recycling and reuse of NMMO2013In: / [ed] Shu Li, Jegatheesan Veeriah, Keir Greg, 2013Conference paper (Refereed)
  • 25.
    Kabir, Maryam M
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dry anaerobic digestion of lignocellulosic and protein residues2015In: Biofuel Research Journal, Vol. 2, no 4, p. 309-316Article in journal (Refereed)
    Abstract [en]

    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.

  • 26.
    Karimi, Keikhosro
    et al.
    Department of Chemical Engineering, Isfahan University of Technology.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent trends in acetone, butanol, and ethanol (ABE) production2015In: Biofuel Research Journal, Vol. 2, no 4, p. 301-308Article in journal (Refereed)
    Abstract [en]

    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.

  • 27. Karimi, Keikhosro
    et al.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent trends in acetone, butanol, and ethanol (ABE) production2015In: Biofuel Research Journal, E-ISSN 2292-8782, Vol. 2, no 4, p. 301-308Article in journal (Refereed)
  • 28.
    Kumar, Rajeev
    et al.
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Karimi, Keikhosro
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Recent updates on lignocellulosic biomass derived ethanol-A review2016In: Biofuel Research Journal, E-ISSN 2292-8782, Vol. 3, no 1, p. 347-356Article in journal (Refereed)
    Abstract [en]

    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.

  • 29. Mirabdollah, A.
    et al.
    Alinezhad, S.
    Feuk-Lagerstedt, Elisabeth
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Optimization of a protoplast transformation method for Bacillus Subtilis, Bacillus megaterium, and Bacillus Cereus by a plasmid pHIS1525.SplipA2009Conference paper (Other academic)
    Abstract [en]

    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.

  • 30. Mirmohamadsadeghi, Safoora
    et al.
    Karimi, Keikhosro
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Improvement of Solid-State Biogas Production from Wood by Concentrated Phosphoric Acid Pretreatment2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 2, p. 3230-3243Article in journal (Refereed)
    Abstract [en]

    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.

  • 31. Mirmohamadsadeghi, Safoora
    et al.
    Karimi, Keikhosro
    Zamani, Akram
    Amiri, Hamid
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Enhanced solid-state biogas production from lignocellulosic biomass by organosolv pretreatment2014In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2014Article in journal (Refereed)
  • 32. Mohseni Kabir, M.
    et al.
    Niklasson, C.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Sárvári Horváth, I.
    University of Borås, School of Engineering.
    Biogas production from lignocelluloses by N-methylmorpholine-N-oxide (NMMO) pretreatment: Effects of recovery and reuse of NMMO2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 161, p. 446-450Article in journal (Refereed)
    Abstract [en]

    The effects of N-methylmorpholine-N-oxide (NMMO) pretreatment on barley straw and forest residues were investigated for biogas production. The pretreatments were performed at 90 °C with 85% NMMO for 3–30 h. The best pretreatment conditions resulted in 100% improvement in methane yield during the subsequent digestion compared to that of the untreated lignocelluloses. Methane yields of 0.23 and 0.15 Nm3 CH4/kg VS were obtained from barley straw and forest residues, respectively, corresponding to 88% and 83% of the theoretical yields. In addition, the effects of the pretreatment with recovered and reused NMMO was also studied over the course of five cycles. Pretreatment with recycled NMMO showed the same performance as the fresh NMMO on barley straw. However, pretreatment of forest residues with recycled NMMO resulted in 55% reduction in methane yield.

  • 33.
    Momayez, Forough
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Isfahan University of Technology.
    Karimi, Keikhosro
    Isfahan University of Technology.
    Karimi, Shiva
    Isfahan University of Technology.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Efficient hydrolysis and ethanol production from rice straw by pretreatment with organic acids and effluent of biogas plant2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 80, p. 50537-50545Article in journal (Refereed)
    Abstract [en]

    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.

  • 34. Murto, Marika
    et al.
    Gereby, Erik
    Holström, David
    del Pilar Castillo, Maria
    Lagerkvist, Anders
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Increased methane production by unused substrates and process development2014Conference paper (Other academic)
  • 35.
    Nair, Ramkumar B
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kabir, Maryam M.
    Lennartsson, Patrik R.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Integrated Process for Ethanol, Biogas, and Edible Filamentous Fungi-Based Animal Feed Production from Dilute Phosphoric Acid-Pretreated Wheat Straw2017In: Applied Biochemistry and Biotechnology, ISSN 0273-2289, E-ISSN 1559-0291, p. 1-15Article in journal (Refereed)
    Abstract [en]

    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)]

  • 36. Pages-Diaz, Jhosane
    et al.
    Westman, Johan
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pereda-Reyes, Ileana
    Sarvari Horvath, Ilona.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Semi-continuous co-digestion of solid cattle slaughterhouse wastes with other waste streams: Interactions within the mixtures and methanogenic community structure.2015In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 273, p. 28-36Article in journal (Refereed)
    Abstract [en]

    The effect of mixt. interactions, i.e., synergy and antagonism, previously obsd. 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 studied. The digestion of SB failed at an OLR of 0.9 g VS/L-day. However, stable performance with higher loadings was obsd. for mixts. 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 obsd. in batch mode due to the different mixt. compns. could be correlated to process performance, as well as the development of the microbial community structure during semi-continuous operation. [on SciFinder(R)]

  • 37.
    Pagés Díaz, Jhosané
    et al.
    University of Borås, School of Engineering.
    Pereda Reyes, Ileana
    Lundin, Magnus
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Co-digestion of different waste mixtures from agro-industrial activities: Kinetic evaluation and synergetic effects2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 23, p. 10834-10840Article in journal (Refereed)
    Abstract [en]

    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.

  • 38.
    Pagés Díaz, Jhosané
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Technical University of Havana “José A. Echeverría”.
    Pereda Reyes, Ileana
    Technical University of Havana “José A. Echeverría”.
    Sanz, Jose Luise
    Autonomous University of Madrid.
    Lundin, Magnus
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    A comparison of process performance during the anaerobic mono-and co-digestion of slaughter house waste through different operational modes2017In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320Article in journal (Refereed)
    Abstract [en]

    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.

  • 39.
    Pagés Díaz, Jhosané
    et al.
    University of Borås, School of Engineering.
    Pereda Reyes, Ileana
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pérez Olmo, Jesús
    An approach to the codigestion process of solid slaughterhouse waste, manure, various crop and municipal solid waste2011Conference paper (Other academic)
    Abstract [en]

    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.

  • 40.
    Pagés Díaz, Jhosané
    et al.
    University of Borås, School of Engineering.
    Pereda Reyes, Ileana
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Lundin, Magnus
    University of Borås, School of Engineering.
    Anaerobic co-digestion of solid slaughterhouse wastes with agro-residues: Synergistic and antagonistic interactions determined in batch digestion assays2014In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 245, p. 89-98Article in journal (Refereed)
    Abstract [en]

    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.

  • 41.
    Pagés Díaz, Jhosané
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Westman, Johan
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pereda Reyes, Ileana
    Centro de Estudio de Ingenieria de Procesos Study Center of Process Engineering (CIPRO), High Polytechnic Institute “José Antonio Echeverría”.
    Sarvari Horvath, Ilona.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Semi-continuous co-digestion of solid cattle slaughterhouse wastes with other waste streams: Interactions within the mixtures and methanogenic community structure.2015In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 273, p. 28-36Article in journal (Refereed)
    Abstract [en]

    The effect of mixt. interactions, i.e., synergy and antagonism, previously obsd. 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 studied. The digestion of SB failed at an OLR of 0.9 g VS/L-day. However, stable performance with higher loadings was obsd. for mixts. 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 obsd. in batch mode due to the different mixt. compns. could be correlated to process performance, as well as the development of the microbial community structure during semi-continuous operation. [on SciFinder(R)]

  • 42.
    Pagés-Díaz, J.
    et al.
    University of Borås, School of Engineering.
    Pereda-Reyes, I.
    Sárvári-Horváth, Ilona
    University of Borås, School of Engineering.
    Lundin, M.
    University of Borås, School of Engineering.
    Synergistic and antagonistic interactions during anaerobic co-digestion of slaughterhouse wastes, manure, various crop and municipal solid waste residues2013Conference paper (Other academic)
  • 43.
    Pagés-Díaz, J.
    et al.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pérez-Olmo, J.
    Pereda-Reyes, I.
    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 conditions2013In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 67, no 5, p. 989-995Article in journal (Refereed)
    Abstract [en]

    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.

  • 44.
    Patinvoh, Regina J.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kalantar Mehrjerdi, Adib
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sarvari, Horvath Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 224, p. 197-205Article in journal (Refereed)
    Abstract [en]

    In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH4/gVSadded/d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation.[on SciFinder (R)]

  • 45.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kalantar Mehrjerdi, Adib
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 224, p. 197-205Article in journal (Refereed)
    Abstract [en]

    In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH4/gVSadded/d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation.[on SciFinder (R)]

  • 46.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Osadolor, Osagie Alex
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Cost effective dry anaerobic digestion in textile bioreactors: Experimental and economic evaluation2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 245, no Pt A, p. 549-555Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study dry anaerobic digestion (dry-AD) of manure bedded with straw using textile-based bioreactor in repeated batches. The 90-L reactor filled with the feedstocks (22-30% total solid) and inoculum without any further treatment, while the biogas produced were collected and analyzed. The digestate residue was also analyzed to check its suitability as bio-fertilizer. Methane yield after acclimatization increased from 183 to 290NmlCH4/gVS, degradation time decreased from 136 to 92days and the digestate composition point to suitable bio-fertilizer. The results then used to carry out economical evaluation, which shows dry-AD in textile bioreactors is a profitable method of handling the waste with maximum payback period of 5years, net present value from $7,000 to $9,800,000 (small to large bioreactors) with internal rate of return from 56.6 to 19.3%.

  • 47.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Osalie, Alex
    University of Borås, Faculty of Textiles, Engineering and Business.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sarvari Horvath, Ilona
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Innovative Pretreatment Strategies for Biogas Production2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. NovArticle in journal (Refereed)
    Abstract [en]

    Biogas or biomethane is traditionally produced via anaerobic digestion, or recently bythermochemical or a combination of thermochemical and biological processes viasyngas (CO and H2) fermentation. However, many of the substrates feedstocks haverecalcitrant structure and difficult to digest (e.g., lignocelluloses or keratins), or theyhave toxic compounds (such as fruit flavors or high ammonia content), or not digestibleat all (e.g., plastics). To overcome these challenges, innovative strategies for enhancedand economically favorable biogas production were proposed in this review. Thestrategies considered are commonly known physical pretreatment, rapid decompression,autohydrolysis, acid- or alkali pretreatments, solvents (e.g. for lignin or cellulose)pretreatments or leaching, supercritical, oxidative or biological pretreatments, as well ascombined gasification and fermentation, integrated biogas production and

  • 48.
    Pereda Reyes, Ileana
    et al.
    Centro de Estudio de Ingenieria de Procesos Study Center of Process Engineering (CIPRO), High Polytechnic Institute “José Antonio Echeverría”.
    Pagés Díaz, Jhosané
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Anaerobic Biodegradation of Solid Substrates from Agroindustrial Activities—Slaughterhouse Wastes and Agrowastes2015In: Biodegradation and Bioremediation of Polluted Systems -: New Advances and Technologies / [ed] Rolando Chamy, Francisca Rosenkranz and Lorena Soler, Croatia: INTECH, 2015, p. 31-64Chapter in book (Other academic)
    Abstract [en]

    Solid wastes from the meat industry are produced in large amounts resulting in a negative impact on the environment if not properly treated. Due to their high content of proteins and fats, these residues are excellent substrates for anaerobic digestion which holds high potential for methane yield. However, possible toxic compounds may be formed during its biodegradation with a consequent failure of the process under long-term operation. The anaerobic co-digestion of such residues with other co-substrates as those generated in agricultural activities has been proposed as a good alternative to overcome these problems. Nevertheless, today there is very little knowledge to assess on mixture interactions connected to wastes composition, biodegradability, and the kinetics of the anaerobic process when complex materials are utilized in ternary and quaternary mixture, specifically when co-digesting solid cattle slaughterhouse waste with agrowaste. It is therefore important to select the right combination of substrates and ratios to obtain synergy instead of antagonism in those mixtures. This chapter aims to provide an overview of the anaerobic digestion of solid slaughterhouse waste and agrowaste, as well as the influence of mixture interactions on its biodegradation.

  • 49.
    Pourbafrani, Mohammad
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Forgacs, Gergely
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Framställning av mångahanda biprodukter från fasta citrusrester2011Patent (Other (popular science, discussion, etc.))
  • 50. Pourbafrani, Mohammad
    et al.
    Forgács, Gergely
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Production of biofuels, limonene and pectin from citrus wastes2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 11, p. 4246-4250Article in journal (Refereed)
    Abstract [en]

    Production of ethanol, biogas, pectin and limonene from citrus wastes (CWs) by an integrated process was investigated. CWs were hydrolyzed by dilute-acid process in a pilot plant reactor equipped with an explosive drainage. Hydrolysis variables including temperature and residence time were optimized by applying a central composite rotatable experimental design (CCRD). The best sugar yield (0.41 g/g of the total dry CWs) was obtained by dilute-acid hydrolysis at 150 degrees C and 6 min residence time. At this condition, high solubilization of pectin present in the CWs was obtained, and 77.6% of total pectin content of CWs could be recovered by solvent recovery. Degree of esterification and ash content of produced pectin were 63.7% and 4.23%, respectively. In addition, the limonene of the CWs was effectively removed through flashing of the hydrolyzates into an expansion tank. The sugars present in the hydrolyzates were converted to ethanol using baker's yeast, while an ethanol yield of 0.43 g/g of the fermentable sugars was obtained. Then, the stillage and the remaining solid materials of the hydrolyzed CWs were anaerobically digested to obtain biogas. In summary, one ton of CWs with 20% dry weight resulted in 39.641 ethanol, 45 m(3) methane, 8.91 limonene, and 38.8 kg pectin. (C) 2010 Elsevier Ltd. All rights reserved.

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