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  • 1.
    Aslanzadeh, S.
    et al.
    University of Borås, School of Engineering.
    Rajendran, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    A comparative study between single- and two-stage anaerobic digestion processes: Effects of organic loading rate and hydraulic retention time2014In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 95, p. 181-188Article in journal (Refereed)
    Abstract [en]

    The effect of an organic loading rate (OLR) and a hydraulic retention time (HRT) was evaluated by comparing the single-stage and two-stage anaerobic digestion processes. Wastes from the food processing industry (FPW) and the organic fraction of the municipal solid waste (OFMSW) were used as substrates. The OLR was increased at each step from 2 gVS/l/d to 14 gVS/l/d, and the HRT was decreased from 10 days to 3 days. The highest theoretical methane yield achieved in the single-stage process was about 84% for the FPW during an OLR of 3 gVS/l/d at a HRT of 7 days and 67% for the OFMSW at an OLR of 2 gVS/l/d and a HRT of 10 days. The single-stage process could not handle a further increase in the OLR and a decrease in the HRT; thus, the process was stopped. A more stable operation was observed at higher OLRs and lower HRTs in the two-stage system. The OLR could be increased to 8 gVS/l/d for the FPW and to 12 gVS/l/d for the OFMSW, operating at a HRT of 3 days. The results show a conclusion of 26% and 65% less reactor volume for the two-stage process compared to the single-stage process for the FPW and the OFMSW, respectively.

  • 2.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Jeihanipour, Azam
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    The Effect of Effluent Recirculation in a Semi-Continuous Two-Stage Anaerobic Digestion System2013In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 6, no 6, p. 2966-2981Article in journal (Refereed)
    Abstract [en]

    The effect of recirculation in increasing organic loading rate (OLR) and decreasing hydraulic retention time (HRT) in a semi-continuous two-stage anaerobic digestion system using stirred tank reactor (CSTR) and an upflow anaerobic sludge bed (UASB) was evaluated. Two-parallel processes were in operation for 100 days, one with recirculation (closed system) and the other without recirculation (open system). For this purpose, two structurally different carbohydrate-based substrates were used; starch and cotton. The digestion of starch and cotton in the closed system resulted in production of 91% and 80% of the theoretical methane yield during the first 60 days. In contrast, in the open system the methane yield was decreased to 82% and 56% of the theoretical value, for starch and cotton, respectively. The OLR could successfully be increased to 4 gVS/L/day for cotton and 10 gVS/L/day for starch. It is concluded that the recirculation supports the microorganisms for effective hydrolysis of polyhydrocarbons in CSTR and to preserve the nutrients in the system at higher OLRs, thereby improving the overall performance and stability of the process.

  • 3.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Jeihanipour, Azam
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Waste textile processing into biogas using two-stage reactors2013Conference paper (Other academic)
  • 4.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    A comparative study between conventional and two stage anaerobic process: Effect of organic loading rate and hydraulic retention time2013In: / [ed] Shu Li, Jegatheesan Veeriah, Keir Greg, Kier Merrin, Chang Chia-Yuan, CESE 2013 , 2013Conference paper (Refereed)
  • 5.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Pretreatment of Lignocelluloses for Biogas and Ethanol Processes2014In: Advances in Industrial Biotechnology / [ed] Ram Sarup Singh, Ashok Pandey, Christian Larroche, Asiatech Publishers Inc , 2014, p. 125-150Chapter in book (Refereed)
  • 6.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Pretreatment of lignocelluloses for biogas and ethanol processes2013In: Advances in Industrial Biotechnology / [ed] Ram Sarup Singh, Ashok Pandey, Christian Larroche, I. K. International Publishing House , 2013, p. 125-150Chapter in book (Other academic)
  • 7. Jeihanipour, A
    et al.
    Aslanzadeh, S
    University of Borås, School of Engineering.
    Rajendran, K
    University of Borås, School of Engineering.
    Balasubramanian, G
    Taherzadeh, M. J
    University of Borås, School of Engineering.
    High-rate biogas production from waste textiles using a two-stage process2013In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 52, p. 128-135Article in journal (Refereed)
    Abstract [en]

    The efficacy of a two-stage Continuously Stirred Tank Reactor (CSTR), modified as Stirred Batch Reactor (SBR), and Upflow Anaerobic Sludge Blanket Bed (UASB) process in producing biogas from waste textiles was investigated under batch and semi-continuous conditions. Single-stage and two-stage digestions were compared in batch reactors, where 20 g/L cellulose loading, as either viscose/polyester or cotton/polyester textiles, was used. The results disclosed that the total gas production from viscose/polyester in a two-stage process was comparable to the production in a single-stage SBR, and in less than two weeks, more than 80% of the theoretical yield of methane was acquired. However, for cotton/polyester, the two-stage batch process was significantly superior to the single-stage; the maximum rate of methane production was increased to 80%, and the lag phase decreased from 15 days to 4 days. In the two-stage semi-continuous process, where the substrate consisted of jeans textiles, the effect of N-methylmorpholine-N-oxide (NMMO) pretreatment was studied. In this experiment, digestion of untreated and NMMO-treated jeans textiles resulted in 200 and 400 ml (respectively) methane/g volatile solids/day (ml/g VS/day), with an organic loading rate (OLR) of 2 g VS/L reactor volume/day (g VS/L/day); under these conditions, the NMMO pretreatment doubled the biogas yield, a significant improvement. The OLR could successfully be increased to 2.7 g VS/L/day, but at a loading rate of 4 g VS/L/day, the rate of methane production declined. By arranging a serial interconnection of the two reactors and their liquids in the two-stage process, a closed system was obtained that converted waste textiles into biogas.

  • 8.
    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.

  • 9.
    Rajendran, K.
    et al.
    University of Borås, School of Engineering.
    Björk, H.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Borås, a Zero Waste City in Sweden2013In: Journal of Development Management, ISSN 2321-0761, Vol. 1, no 1, p. 3-8Article in journal (Other academic)
    Abstract [en]

    Waste is a wealthy resource in the city of Borås in Sweden. The city has developed a sustainable waste management mechanism by reducing landfill, recovering fuel from the waste and recycling in collaboration with University of Borås, local municipality and other private partners. The system was designed back in 1986 to convert waste into value- added products such as biogas, electricity and heat. Hardly less than 1% of waste ends in landfills, thus Borås has given a new model of utilizing waste in a useful and economical way for a better environment. In most of the countries the waste is thrown away in the landfills which leads to health hazards, safety issues and loss of valuable resources. The Borås model emphasizes on ''reduce, recycle and recover energy'' before dumping. Before 1996 more than 40% of waste was landfilled in Sweden and today it has approached to zero landfill. The household waste is sorted in 30 fractions and then used. In a city of 100,000 population through using waste more than 3 million m3 biogas is produced every year which runs the buses, garbage trucks and around 300 CNG vehicles in the city. 960 MWh heat and electricity is also generated everyday. More than 90% recycling of PET and aluminum bottles is done in Sweden. The University of Borås actively conducts research and workshops in the sector. This public, private partnership model has made Borås a zero waste city.

  • 10.
    Rajendran, K.
    et al.
    University of Borås, School of Engineering.
    Kankanala, H.R.
    Lundin, M.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Process Simulation Model for Anaerobic Digestion2013Conference paper (Refereed)
    Abstract [en]

    In this study, a novel process simulation model (PSM) was developed for anaerobic digestion using Aspen Plus® (version 7.3.2). PSM has two parts, one for hydrolysis working based on extent of reaction and the other on kinetics of reactions. A total of 53 reactions were used in the model including inhibitions, rate kinetics, pH, ammonia, volume and HRT. Each reaction set in the kinetic reactor has a FORTRAN program to calculate the kinetics of biogas production. PSM was validated with earlier research studies and industrial experiments in Aspen Plus®. The P-value after statistical analysis was found to be 0.324, which showed there was no significant difference between different validations, even after a change in process conditions, loading rate, HRT and substrate. The sensitivity analysis with a ±10% change in composition and extent of reaction would result in average 4.56% higher value than the experimental value.

  • 11.
    Rajendran, K.
    et al.
    University of Borås, School of Engineering.
    Rajoli, S.
    Teichert, O.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Impacts of retrofitting analysis on first generation ethanol production: process design and techno-economics2014In: Bioprocess and biosystems engineering (Print), ISSN 1615-7591, E-ISSN 1615-7605, Vol. 38, no 2Article in journal (Refereed)
    Abstract [en]

    More than half of the bioethanol plants in operation today use corn or grains as raw materials. The downstream processing of mash after fermentation to produce ethanol and distiller grains is an energy-demanding process, which needs retrofitting for optimization. In addition, the fluctuation in the ethanol and grain prices affects the overall profitability of the plant. For this purpose, a process simulation was performed in Aspen Plus® based on an existing industrial plant located in Sweden. The simulations were compared using different scenarios including different concentrations of ethanol, using the stillage for biogas production to produce steam instead of distiller grains as a by-product, and altering the purity of the ethanol produced. Using stillage for biogas production, as well as utilizing the steam, reduced the overall energy consumption by 40 % compared to the plant in operation. The fluctuations in grain prices had a high impact on the net present value (NPV), where grain prices greater than 349 USD/ton reached a zero NPV. After 20 years, the plant in operation producing 41,600 tons ethanol/year can generate a profit of 78 million USD. Compared to the base case, the less purified ethanol resulted in a lower NPV of 30 million USD.

  • 12.
    Rajendran, Karthik
    University of Borås, Faculty of Textiles, Engineering and Business.
    Industrial Bioprocess Developments for Biogas and Ethanol Production2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Current biofuels face a noteworthy misfortune on commercialization because of its economiccomparison with low-cost fuel from the oil reserves. To compete with gasoline as a fuel, thebiofuels need to be economically feasible and demonstrated on a large-scale. Biogas and ethanolhave a great potential as commercial biofuels, even though it has difficulties, for example, highcapitalinvestment, absence of demonstrated innovations, and availability of raw materials and soforth. This thesis focuses on different application-driven bioprocess developments for improvingthe techno-economic feasibility of the biogas and ethanol industries.

    The biogas industry was studied from three different perspectives:

    1) Modeling approach in which a Process Simulation Model (PSM) model was developed forpredicting the biogas productions, as exploiting new substrates is vital for a biogas industrygrowth. The PSM model was created using Aspen Plus® which includes 46 reactions of differentphases in the Anaerobic Digestion (AD) processes. It also contains certain important processparameters, thermodynamics, rate-kinetics, and inhibitions involved in the AD processes. PSMwas a library model for the AD processes, which was validated against the laboratory andindustrial data. The validation showed that the PSM predicted the biogas production about 5% inexcess, which could ease the biogas industry to predict biogas from new substrates.

    2) Simulation approach to study the imperative components affecting the profitability of theplant. For this purpose, a local municipality plant was studied under distinct situations. The choiceof upgrading method, capacity, cost of waste and its processing, number of digesters used, etc.were exploited. The results showed that the collection and transportation fee, landfilling fee, andthe reduced operation of a plant were the main considerations in influencing its profitability.Moreover, it was identified that for bigger cities the decentralization strategy could beat theexpense of collection and transportation of waste, and the plant could obtain a 17.8% return oninvestment.

    3) Rethinking digester technology in which the cost of the digester was significantly lessenedusing a cutting-edge textile, which was principally intended for developing countries. The digestercost played an important role in consuming biogas for different applications. The textile digesterwas tested on a laboratory scale, followed by field tests in different countries including India,Indonesia, and Brazil. Textile digesters cost one-tenth of the conventional digesters, and thepayback was more or less between 1–3 years, when replacing the Liquefied Petroleum Gas (LPG)and kerosene as a cooking fuel for households.

    When it comes to ethanol, the first generation ethanol production using grains was financiallypossible with a payback of about 13 years. Nonetheless, with the fluctuation of the oil prices, theethanol industries need to look for alternative sources of revenues. Different retrofits wereconsidered, including the effect of thin-stillage/whole-stillage to ethanol and biomass, in additionto the integration of the first and second generation ethanol production. The results revealed that4% additional ethanol could be obtained when the thin-stillage was converted into ethanol andfungal biomass, while the payback was reduced to 11.5 years. The integration of the first andsecond generation ethanol production revealed that it has a positive influence on the overalleconomics of the process with a payback of 10.5 years. This could help the ethanol industries toconsider a revamp for a better environmental, economic, and energy efficient process.

  • 13.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Aslanzadeh, Solmaz
    University of Borås, School of Engineering.
    Johansson, Fredrik
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Experimental and economical evaluation of a novel biogas digester2013In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 74, p. 183-191Article in journal (Refereed)
    Abstract [en]

    Many developing countries face an energy demand to satisfy the daily needs of the people. Household biogas digesters are among the interesting solutions to meet the energy demands for cooking and lighting, and at the same time taking care of the kitchen wastes. In this study, a novel textile-based biogas digester was developed. The digester was evaluated for biogas production from a synthetic nutrient and an organic fraction of municipal solid waste (OFMSW) as substrates for more than a year. The obtained biogas productivity in both experiments was 570 L/kgVS/day, which indicates that the digester is as efficient in handling of OFMSW as the synthetic nutrients. Based on the obtained biogas production data, the techno-economic evaluation and sensitivity analysis for the process were performed, replacing LPG and kerosene consumption with biogas in households. A 2-m3 digester can supply the fuel needed for cooking for a family of 4–6 people. The sum of investment and 15-years operational costs of this digester was 656 USD, which can be compared with 1455 USD for subsidized-LPG and 975 USD for kerosene, respectively. The results from the sensitivity analysis show that it was a positive investment, unless the price of kerosene goes down to less than 0.18 USD/L.

  • 14.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Aslanzadeh, Solmaz
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Household biogas digesters: a review2012In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 5, no 8, p. 2911-2942Article in journal (Refereed)
    Abstract [en]

    This review is a summary of different aspects of the design and operation of small-scale, household, biogas digesters. It covers different digester designs and materials used for construction, important operating parameters such as pH, temperature, substrate, and loading rate, applications of the biogas, the government policies concerning the use of household digesters, and the social and environmental effects of the digesters. Biogas is a value-added product of anaerobic digestion of organic compounds. Biogas production depends on different factors including: pH, temperature, substrate, loading rate, hydraulic retention time (HRT), C/N ratio, and mixing. Household digesters are cheap, easy to handle, and reduce the amount of organic household waste. The size of these digesters varies between 1 and 150 m3. The common designs include fixed dome, floating drum, and plug flow type. Biogas and fertilizer obtained at the end of anaerobic digestion could be used for cooking, lighting, and electricity.

  • 15.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Björk, Hans
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Waste Recovery International Partnership: A Model to Transfer Technology and Create Local Development2014In: Design, Waste & Dignity, CNPq, Olhares , 2014, p. 293-304Chapter in book (Other academic)
  • 16.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Jeihanipour, Azam
    Aslanzadeh, Solmaz
    University of Borås, School of Engineering.
    Balasubramanian, Gopinath
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Could it be Possible to Convert Waste-Textiles to Biogas? Yes!2012Conference paper (Other academic)
    Abstract [en]

    A two-stage process was developed by serial inter-connection between CSTR (Continuously Stirred Tank Reactor) and UASB (Upflow Anaerobic Sludge Bed) to produce high-rate biogas from waste textiles. Most of the textiles contain cellulose, which could be a potential substrate for biogas production. Blue jeans textile (pretreated and untreated) was used as waste textile in this process to investigate biogas production under semi-continuous conditions. Jeans was pretreated using 85% NMMO (N-Methyl-Morpholine-Oxide), an environmental friendly solvent at 120 °C for 3 h. OLR (Organic Loading Rate) was increased in the order of 2, 2.7, and 4 gVS/L/day respectively. Pretreatment had a significant effect on the biogas production. NMMO pretreatment doubled the biogas yield, during an OLR of 2 g VS/L/day compared to untreated jeans. The OLR could successfully be increased to 2.7 g VS/L/day resulted in 91% and 96% theoretical yield for untreated jeans and pretreated jeans respectively. However, further increase in OLR did not increase the methane production. For the complete process, COD (Chemical Oxygen Demand) efficiency was high for untreated jeans with 65.1% followed by treated jeans with 39.5% in the UASB. CSTR possessed the major share of biogas production for both textiles. Considering the fact that, textile is one of the largest consumer products, a proper way of disposal or treatment is necessary. By biogas production, waste textile could also be treated and a value-added product was obtained.

  • 17.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Kankanala, Harshavardhan
    Lundin, Magnus
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Process Simulation Model for Biogas Production2013Conference paper (Other academic)
  • 18.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Kankanala, Harshavardhan R.
    Lundin, Magnus
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J
    University of Borås, School of Engineering.
    A Novel Process Simulation Model (PSM) for Anaerobic Digestion Using Aspen Plus2014Other (Other academic)
    Abstract [en]

    A novel process simulation model (PSM) was developed for biogas production in anaerobic digesters using AspenPlus®. The PSM is a library model of anaerobic digestion, which predicts the biogas production from any substrate at any given process condition. A total of 46 reactions were used in the model, which include inhibitions, rate-kinetics, pH, ammonia, volume, loading rate, and retention time. The hydrolysis reactions were based on the extent of the reaction, while the acidogenic, acetogenic, and methanogenic reactions were based on the kinetics. The PSM was validated against a variety of lab and industrial data on anaerobic digestion. The P-value after statistical analysis was found to be 0.701, which showed that there was no significant difference between discrete validations and processing conditions. The sensitivity analysis for a ±10% change in composition of substrate and extent of reaction results in 5.285% higher value than the experimental value. The model is available at http://hdl.handle.net/2320/12358 (Rajendran et al., 2013b).

  • 19.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Kankanala, Harshavardhan R.
    Lundin, Magnus
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Process simulation model for biogas production2013Conference paper (Other academic)
  • 20.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Kankanala, Harshavardhan R
    Martinsson, Rakel
    Taherzadeh, Mohammad J
    University of Borås, School of Engineering.
    Uncertainty over techno-economic potentials of biogas from municipal solid waste (MSW): A case study on an industrial process2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 125, p. 84-92Article in journal (Refereed)
    Abstract [en]

    In this study, biogas production from the organic fraction of the MSW (OMSW) was simulated in six different scenarios, using Aspen plus® based on industrial data. The economic evaluations were made using the Aspen process economic analyzer, considering the plant size and the upgrading methods. The base case had an annual processing capacity of 55,000 m3 OMSW. The capital costs and the net present value (NPV) after 20 years of operation were 34.6 and 27.2 million USD, respectively. The base case was compared to the modified scenarios, which had different upgrading methods, processing capacities, addition of biogas from wastewater sludge treatment, and variation of the substrate (OMSW) between ±200 USD/ton. The sensitivity analyses were carried out considering the cost of the OMSW imposed on citizens for collection and transportation of wastes and the different sizes of the plant. The result suggests that producing biogas and selling it, as a vehicle fuel from OMSW is a profitable venture in most scenarios. However, there are some uncertainties, including the collection and transportation costs, landfilling fee, and process operation at lower capacities, which affect its profitability.

  • 21.
    Rajendran, Karthik
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajoli, Sreevathsava
    Teichert, Oliver
    Taherzadeh, Mohammad J
    University of Borås.
    Impacts of retrofitting analysis on first generation ethanol production: process design and techno-economics.2015In: Bioprocess and biosystems engineering (Print), ISSN 1615-7591, E-ISSN 1615-7605, Vol. 38, no 2, p. 389-397Article in journal (Refereed)
    Abstract [en]

    More than half of the bioethanol plants in operation today use corn or grains as raw materials. The downstream processing of mash after fermn. to produce ethanol and distiller grains is an energy-demanding process, which needs retrofitting for optimization. In addn., the fluctuation in the ethanol and grain prices affects the overall profitability of the plant. For this purpose, a process simulation was performed in Aspen Plus based on an existing industrial plant located in Sweden. The simulations were compared using different scenarios including different concns. of ethanol, using the stillage for biogas prodn. to produce steam instead of distiller grains as a byproduct, and altering the purity of the ethanol produced. Using stillage for biogas prodn., as well as utilizing the steam, reduced the overall energy consumption by 40 % compared to the plant in operation. The fluctuations in grain prices had a high impact on the net present value (NPV), where grain prices greater than 349 USD/ton reached a zero NPV. After 20 years, the plant in operation producing 41,600 tons ethanol/yr can generate a profit of 78 million USD. Compared to the base case, the less purified ethanol resulted in a lower NPV of 30 million USD. [on SciFinder(R)]

  • 22.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Process Simulation Model for Biogas Production2014Conference paper (Refereed)
  • 23.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Pretreatment of Lignocellulosic Materials2014In: Bioprocessing of Renewable Resources to Commodity Bioproducts / [ed] V. Bisaria, A. Kondo, Wiley , 2014, p. 43-76Chapter in book (Refereed)
  • 24.
    Rajendran, Karthik
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Techno-Economic Evaluation of an Industrial Biogas Plant2014Conference paper (Other academic)
1 - 24 of 24
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