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  • 1. 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.

  • 2.
    Kabir, Maryam M
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bioprocessing of Recalcitrant Substrates for Biogas Production2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The application of anaerobic digestion (AD) as a sustainable waste management technology is growing worldwide, due to high energy prices as well as increasingly strict environmental regulations. The growth of the AD industry necessitates exploring new substrates for their utilisation in AD processes. The present work investigates the AD of two recalcitrant biomass: lignocelluloses and keratin-rich residues. The complex nature of these waste streams limits their biological degradation; therefore, suitable pre-processing is required prior to the AD process.In the first part of the study, the effects of organic solvent pre-treatments on bioconversion of lignocelluloses (straw and forest residues) to biogas were evaluated. Pre-treatment with N-methylmorpholine-N-oxide (NMMO) resulted in minor changes in the composition of the substrates, while their digestibility significantly increased. Furthermore, due to the high cost of the NNMO, the effect of pre-treatment with the recycled solvent was also explored. Since it was found that the presence of small traces of NMMO in the system after the treatment has inhibitory effects on AD, pre-treatments of forest residues using other organic solvents, i.e. acetic acid, ethanol, and methanol, were investigated too. Although pre-treatments with acetic acid and ethanol led to the highest methane yields, the techno-economical evaluation of the process showed that pre-treatment with methanol was the most viable economically, primarily due to the lower cost of methanol, compared to that of the other solvents.In the second part of the work, wool textile wastes were subjected to biogas production. Wool is mainly composed of keratin, an extremely strong and resistible structural protein. Thermal, enzymatic and combined treatments were, therefore, performed to enhance the methane yield. The soluble protein content of the pre-treated samples showed that combined thermal and enzymatic treatments had significantly positive effects on wool degradation, resulting in the highest methane yields, i.e. 10–20-fold higher methane production, compared to that obtained from the untreated samples.In the last part of this thesis work, dry digestion of wheat straw and wool textile waste, as well as their co-digestion were studied. The total solid (TS) contents applied in the digesters were between 6–30% during the investigations. The volumetric methane productivity was significantly enhanced when the TS was increased from 6 to 13–21%. This can be a beneficial factor when considering the economic feasibility of large-scale dry AD processes.

  • 3.
    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)
  • 4.
    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.

  • 5. 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)
  • 6.
    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.

  • 7.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Forgács, Gergely
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    6 Biogas from Wastes2015In: Resource Recovery to Approach Zero Municipal Waste / [ed] Mohammad J. Taherzadeh, Tobias Richards, CRC Press, 2015Chapter in book (Refereed)
  • 8.
    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.

  • 9.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Mirahmadi, Kambiz
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Effect of sodium hydroxide pretreatment on enzymatic hydrolysis of softwoods and hardwoods2009Conference paper (Other academic)
  • 10.
    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.

  • 11.
    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)
  • 12.
    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)
  • 13.
    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.

  • 14.
    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)]

  • 15. Shafiei, Marzieh
    et al.
    Kabir, Maryam M.
    University of Borås, School of Engineering.
    Zilouei, Hamid
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    Techno-economical study of biogas production improved by steam explosion pretreatment2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 148, p. 53-60Article in journal (Refereed)
    Abstract [en]

    Economic feasibility of steam explosion pretreatment for improvement of biogas production from wheat straw and paper tube residuals was investigated. The process was simulated by Aspen plus®, and the economical feasibility of five different plant capacities was studied by Aspen Process Economic Analyzer. Total project investment of a plant using paper tube residuals or wheat straw was 63.9 or 61.8 million Euros, respectively. The manufacturing cost of raw biogas for these two feedstocks was calculated to 0.36 or 0.48 €/m3 of methane, respectively. Applying steam explosion pretreatment resulted in 13% higher total capital investment while significantly improved the economy of the biogas plant and decreased the manufacturing cost of methane by 36%. The sensitivity analysis showed that 5% improvement in the methane yield and 20% decrease in the raw material price resulted in 5.5% and 8% decrease in the manufacturing cost of methane, respectively.

  • 16.
    Sárvári Horváth, Ilona
    et al.
    University of Borås, School of Engineering.
    del Pilar Castillo, Maria
    Berglund Odhner, Peter
    Teghammar, Anna
    University of Borås, School of Engineering.
    Kabir, Maryam M.
    University of Borås, School of Engineering.
    Olsson, Marcus
    Ascue, Johnny
    Biogas från lignocellulosa Tekno: ekonomisk utvärdering av förbehandling med NMMO2013Report (Other academic)
    Abstract [en]

    Biogas has been identified as one of the most cost - effective renewable fuels. In order to increase biogas production, yields from traditionally substrates either need to be improved or other alternative substrates must be made available for anaerobic digestion. Cellulose and lignocellulose rich wastes are available in large amounts and have great potential to be utilized for biogas production. This project focused on the opti mization of the pretreatment conditions when using the organic solvent N - methylmorpholine - N - oxide (NMMO) to enhance the methane yield from forest residues and straw. It also focused on a techno - economic evaluation of this pre - treatment technology. NMMO has previously been shown to be effective in dissolving cellulose and, as a consequence, in increasing the methane yield during the subsequent digestion. The goal of this project was to develop a technology that increases energy production from domestic subst rates in a cost - effective and environmentally friendly way. The treatment works well at lower temperatures (90°C), which means that water from the district heating system can advantageously be used in the treatment. The results showed that treatment with NMMO at 90°C doubles the methane yield from forest residues and increases the methane yield from straw by 50 %. For the techno - economic evaluation, the base case was assumed to be a facility with a capacity of 100 000 tones forest residues/year. After a w ashing and filtration step, the treated material will be utilized in a co - digestion process where 33% of the incoming material consists of forest residues and the rest is source - sorted household waste. The scale - up, process design, simulation and calculati ons were made using the software tool Intelligen SuperPro Design ® . The total investment costs were calculated to be about 145 million €, when forest residues or straw are to be used as raw material. Costs for operation (i.e. raw materials, energy, waste ma nagement, maintenance and personnel costs) were set against the incomes from the products (i.e. methane, carbon dioxide and the lignin - rich digested residue) to see if the process was profitable. The internal return rate (IRR), a parameter that indicates w hether a process is profitable or not, indicated that evaluated processes with capacities over 50 000 tons forest residues/year are profitable. However, co - digestion of forest residues with sewage sludge instead of household waste was not profitable. Both the laboratory results and the energy and economic calculations showed that the washing and filtration step is critical for the proposed process. The energy balance calculation resulted in an EROI value of 0.5, which means that the produced methane from fo rest residues counted up only the half of the energy needed for the treatment as well as NMMO separation and recycling. It is important to separate the NMMO well after the treatment, since remaining NMMO at concentrations higher than 0.002% were found to i nhibit the subsequent digestion step. Also it was showed out to be important that the washing step operates with small amounts of water to save energy within the NMMO recovery. A rotary vacuum filtration is therefore recommended for the washing and filtrat ion step, and a mechanical vapor design is recommended for the evaporation, saving up to 70 - 90% energy compared to a conventional design. Treatment of straw with recycled instead of fresh NMMO has also been tested and equal amounts of methane were obtain ed. After a well - functioning washing and filtration step, NMMO could not be detected in the digestate residue.

1 - 16 of 16
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