Biochemical Engineering Journal (v.116, #C)


Valorization of organic residues for the production of added value chemicals: A contribution to the bio-based economy by Daniel Pleissner; Qingsheng Qi; Cuijuan Gao; Cristina Perez Rivero; Colin Webb; Carol Sze Ki Lin; Joachim Venus (3-16).
Establishing of a bio-based and green society depends on the availability of inexpensive organic carbon compounds, which can be converted by microbes into various valuable products. Around 3.7 × 109  t of agricultural residues and 1.3 × 109  t of food residues occur annually worldwide. This enormous amount of organic material is basically considered as waste and incinerated, anaerobically digested or composted for the production of heat, power or fertilizers. However, organic residues can be used as nutrient sources in biotechnological processes. For example, organic residues can be hydrolyzed to glucose, amino acids and phosphate by chemical and/or biological methods, which are utilizable as nutrients by many microbes. This approach paves the way toward the establishment of a bio-based economy and an effective organic residues valorization for the formation of bio-based chemicals and materials. In this review, valorization of organic residues in biotechnological processes is presented. The focus is on the production of three industrially important added value chemicals, namely succinic acid, lactic acid and fatty acid-based plasticizer, which have been used for the synthesis of environmentally benign materials and food supplements. Furthermore, utilization strategies of residues coming from fruit and vegetable processing are introduced.
Keywords: Succinic acid; Lactic acid; Fatty acids; Bio-plasticizer; Agricultural residues; Food residues; Vegetable residues;

Development of advanced biorefinery concepts using magnetically responsive materials by Ivo Safarik; Kristyna Pospiskova; Eva Baldikova; Mirka Safarikova (17-26).
Utilization of magnetic materials and particles brings a considerable simplification into biorefinery technologies, based on their fast, simple and selective separation even from various difficult-to-handle environments and conditions. Additionally, application of magnetically responsive (bio)catalysts can significantly improve the productivity, economic feasibility, sustainability and product quality during the biorefinery processes. This review is focused on the presentation of typical examples of magnetic materials applicable in biorefinery, especially for the preparation of magnetically responsive enzymatic and whole-cell biocatalysts, as well as solid acid/base catalysts, magnetically responsive adsorbents or magnetically separable materials with suitable properties for isolation and purification of target compounds from complex mixtures. This brief overview emphasises remarkable possibilities of magnetic materials and magnetic techniques and their application potential in biorefinery technologies.
Keywords: Separation; Biocatalysis; Immobilization; Bioconversion; Magnetic particles; Magnetic enzymes and cells;

Extraction and bioconversion of kaempferol metabolites from cauliflower outer leaves through fungal fermentation by Nguyen Thai Huynh; Guy Smagghe; Gerard Bryan Gonzales; John Van Camp; Katleen Raes (27-33).
Cauliflower outer leaves contain bioactive compounds, therefore fermentation could be a strategy to release phenolic compounds and their metabolites and thus increase their valorization potential. This study aimed to evaluate the release and metabolism of different filamentous fungi. The fermentation with Aspergillus sojae was found to extract the highest level of total phenolic compounds (321 mg rutin equivalents (RE)/100 g fresh weight (FW)) after 1 day, which was 3 times higher compared to the unfermented sample (113 mg RE/100 g FW). The most dominant kaempferol metabolites were kaempferol-3-O-diglucoside in all fermented samples (38–126 mg RE/100 g FW) and kaempferol-3-O-diglucoside-7-O-glucoside in the unfermented sample (34.8 mg RE/100 g FW). Furthermore, in all fungal treated samples, the phenolic profile shifted to a profile with less or no carbohydrate moieties at the 3- or 7-carbon position. These results indicate the potential of solid-state fermentation to obtain different phenolic-rich extracts, with a unique profile in phenolic compounds, depending on the fungal strain used.
Keywords: Cauliflower; Flavonoid metabolism; Kaempferol; Filamentous fungi; Bioconversion;

Valorisation of effluents obtained from chemical and enzymatic chitin production of Illex argentinus pen by-products as nutrient supplements for various bacterial fermentations by José A. Vázquez; Romain Caprioni; Margarita Nogueira; Araceli Menduiña; Patricia Ramos; Ricardo I. Pérez-Martín (34-44).
The industrial production of chitin generates large volumes of protein effluents that need to be handled and depurated before discharge. The current study highlights the suitability of four effluents, derived from the chemical and enzymatic hydrolysis of Illex argentinus pen to produce β-chitin, as peptones for the growth and metabolite production of six bacteria with different nutrient requirements. Batch cultures were carried out determining the growths by dry weight and viable cell counts and modelling kinetics using the logistic equation. Two lactic acid bacteria were perfectly supported by alternative media formulated with chitin effluents and the results were better than those found in commercial ones. For the other four bacteria, the biomasses in chitin peptones were lower but the number of produced cells was similar to those defined using Marine medium (MM) and tryptone-soy broth (TSB). An economic assessment demonstrated the profitability achieved when commercial peptones are replaced by those generated from squid pen: reduction of costs by 6 times for lactic acid bacteria, 50-100 times for marine bacteria and 6–17 times for Gram (+) bacteria.
Keywords: Microbial growth; Waste-water treatment; Boconversion; Peptones; Illex argentinus pen by-products; Chitin production;

From by-product to valuable components: Efficient enzymatic conversion of lactose in whey using β-galactosidase from Streptococcus thermophilus by Barbara Geiger; Hoang-Minh Nguyen; Stefanie Wenig; Hoang Anh Nguyen; Cindy Lorenz; Roman Kittl; Geir Mathiesen; Vincent G.H. Eijsink; Dietmar Haltrich; Thu-Ha Nguyen (45-53).
β-Galactosidase from Streptococcus thermophilus was overexpressed in a food-grade organism, Lactobacillus plantarum WCFS1. Laboratory cultivations yielded 11,000 U of β-galactosidase activity per liter of culture corresponding to approximately 170 mg of enzyme. Crude cell-free enzyme extracts obtained by cell disruption and subsequent removal of cell debris showed high stability and were used for conversion of lactose in whey permeate. The enzyme showed high transgalactosylation activity. When using an initial concentration of whey permeate corresponding to 205 g L−1 lactose, the maximum yield of galacto-oligosaccharides (GOS) obtained at 50 °C reached approximately 50% of total sugar at 90% lactose conversion, meaning that efficient valorization of the whey lactose was obtained. GOS are of great interest for both human and animal nutrition; thus, efficient conversion of lactose in whey into GOS using an enzymatic approach will not only decrease the environmental impact of whey disposal, but also create additional value.
Keywords: Whey permeate; Galacto-oligosaccharides (GOS); β-galactosidase; Prebiotics; Transgalactosylation;

Integration of chlorogenic acid recovery and bioethanol production from spent coffee grounds by Anna Burniol-Figols; Katarzyna Cenian; Ioannis V. Skiadas; Hariklia N. Gavala (54-64).
Display OmittedSpent coffee grounds (SCG) are an abundant by-product of the coffee industry with a complex composition that makes them a promising feedstock for a biorefinery. The objective of this study was to evaluate SCG as a substrate for combined chlorogenic acid and bioethanol production after dilute acid hydrolysis. The effect of phenolics extraction on the downstream process was evaluated exhibiting no loss of sugars and an increase in the sugar release efficiency during the dilute acid hydrolysis. In order to suggest an economically feasible process, phenolics extraction and dilute acid hydrolysis prior to ethanol fermentation were optimised by means of experimental design. The responses of the designs were not only the efficiencies of the processes, but also a balance between product recovery and estimated costs. In both cases, decreased efficiencies obtained with low liquid-solid ratios were countervailed by increased products concentrations and higher economical performance. Under the optimised conditions, the purity of the phenolics extract (32%) could allow it to enter the market as a dietary supplement of chlorogenic acid, a product with high trade value. Moreover, a concentration of 3.9% (w/v) ethanol was reached upon fermentation of the hydrolysate of SCG after extraction and dilute acid hydrolysis.
Keywords: Bioconversion; Ethanol; Process integration; Fermentation; Spent coffee grounds; Chlorogenic acid;

In the present study the whole slurry obtained after different pretreatment methods applied on sunflower straw (SS) biomass, was used for biological production of hydrogen (BHP) and ethanol (BEP). BHP from pretreated SS was studied in batch experiments using mixed anaerobic sludge, via simultaneous saccharification and fermentation (SSF), while for BEP, SSF was carried out using the xylose – fermenting yeast Pichia stipitis. The experimental results obtained showed that for BHP, alkaline pretreatment with 20 g NaOH/100 gTS was optimal, leading to the highest hydrogen yield of 155.3 ± 6.5 L/kg TS. This yield was 52.5 times higher than the respective of raw SS (2.9 ± 0.0 LH2/kgTS) without enzyme addition. Pretreatment with the same chemical loadings of HCl or H2SO4 resulted in the lowest BHP yields, due to the generation of inhibitory compounds. Although pretreatment with 20 g H2SO4/100 gTS also caused inhibition of P. stipitis giving the lowest BEP yield, pretreatment with 20 g HCl/100 gTS led to the highest BEP yield of 104.78 ± 0.08 mg ethanol/gTS, indicating the varying sensitivity of different microbial species to the inhibitory compounds that are generated during pretreatment.
Keywords: Ethanol; Hydrogen; Sunflower straw; Pretreatment; P. stipitis; Inhibition;

Waste cleaning waste: Ammonia abatement in bio-waste anaerobic digestion by soluble substances isolated from bio-waste compost by Matteo Francavilla; Luciano Beneduce; Giuseppe Gatta; Enzo Montoneri; Massimo Monteleone; Davide Mainero (75-84).
Soluble bio-based substances are isolated from the alkaline hydrolysate of composted urban gardening wastes. These substances are capable to reduce the ammonia content in municipal biowaste anaerobic digestates. The present work reports the anaerobic fermentation of the organic humid fraction of solid municipal biowaste carried out in the presence the above soluble substances, added at 0.05–0.2% concentration in fermentation slurry. The results show that the ammonia in the digestate obtained under these conditions is 70–100% lower than the ammonia present in the digestate of control fermentation without addition of soluble biobased substances. Operational cost savings (up to 1.1 € per abated ammonia N kg) may result for the anaerobic digestion performed in the presence of the above soluble susbtances, compared to conventional technology for the digestate secondary treatment.
Keywords: Anaerobic processes; Waste treatment; Biogas; Bioprocess design; Ammonia abatement; Biorefinery;

Effect of fed-batch vs. continuous mode of operation on microbial fuel cell performance treating biorefinery wastewater by Tyler C. Pannell; R. Kannaiah Goud; Daniel J. Schell; Abhijeet P. Borole (85-94).
Bioelectrochemical systems have been shown to treat low-value biorefinery streams while recovering energy, however, low current densities and anode conversion efficiencies (ACE) limit their application. A bioanode was developed via enrichment of electroactive biofilm under fed-batch and continuous feeding conditions using corn stover-derived waste stream. The continuously-fed MFC exhibited a current density of 5.8 ± 0.06 A/m2 and an ACE of 39% ± 4. The fed-batch MFC achieved a similar current density and an ACE of 19.2%, however, its performance dropped after 36 days of operation to 1.1 A/m2 and 0.5%, respectively. In comparison, the ACE of the continuously-fed MFC remained stable achieving an ACE of 30% ± 3 after 48 days of operation. An MFC treating a biorefinery stream post fuel separation achieved a current density of 10.7 ± 0.1 A/m2 and an ACE of 57% ± 9 at an organic loading of 12.5 g COD/L-day. Characterization of the microbial communities indicate higher abundance of Firmicutes and Proteobacteria and lower abundance of Bacteriodetes and a higher level of Geobacter spp. (1.4% vs. 0.2%) in continuously-fed MFC vs. fed-batch MFC. The results demonstrate that limiting substrate to the equivalent maximum current that the anode can generate, maintains MFC performance over a long term for high strength wastewaters, such as those generated in the biorefinery.
Keywords: Fermentation inhibitors; Bioelectrochemical system; Exoelectrogenic; Biofilm-forming; Hydrolysate; Corn stover;

The effect of flow rate and recycle on the conversion of a biomass-derived pyrolysis aqueous phase in a microbial electrolysis cell (MEC) were investigated to demonstrate production of renewable hydrogen in biorefinery. A continuous MEC operation was investigated under one-pass and recycle conditions using the complex, biomass-derived, fermentable, mixed substrate feed at a constant concentration of 0.026 g/L, while testing flow rates ranging from 0.19 to 3.6 mL/min. This corresponds to an organic loading rate (OLR) of 0.54–10 g/L-day. Mass transfer issues observed at low flow rates were alleviated using high flow rates. Increasing the flow rate to 3.6 mL/min (3.7 min HRT) during one-pass operation increased the hydrogen productivity 3-fold, but anode conversion efficiency (ACE) decreased from 57.9% to 9.9%. Recycle of the anode liquid helped to alleviate kinetic limitations and the ACE increased by 1.8-fold and the hydrogen productivity by 1.2-fold compared to the one-pass condition at the flow rate of 3.6 mL/min (10 g/L-d OLR). High COD removal was also achieved under recycle conditions, reaching 74.2 ± 1.1%, with hydrogen production rate of 2.92 ± 0.51 L/L-day. This study demonstrates the advantages of combining faster flow rates with a recycle process to improve rate of hydrogen production from a switchgrass-derived stream in the biorefinery.
Keywords: Switchgrass; Bio-oil aqueous phase; Pyrolysis; Integrated hydrogen production; Organic loading rate; Hydraulic retention time;

Catalytic upgrading of pretreated algal bio-oil over zeolite catalysts in supercritical water by Peigao Duan; Yuping Xu; Feng Wang; Bing Wang; Weihong Yan (105-112).
Display OmittedWe report the catalytic hydrothermal upgrading of pretreated algal bio-oil. The reaction was performed at 400 °C for 240 min with the addition of 6 MPa H2 and 10 wt.% zeolite catalyst in supercritical water ( ρ H 2 O  = 0.025 g/cm3). Nine zeolites (Hβ, HZSM-5 (SiO2/Al2O3  = 25:1), HZSM-5 (SiO2/Al2O3  = 50:1), HZSM-5 (SiO2/Al2O3  = 170:1), HY (5% Na2O), HY (0.8% Na2O), SAPO-11, MCM-41 (50% Si), and MCM-41 (100% Si) were screened to investigate their effects on the yields of the product fraction and the properties (e.g., elemental composition and heating value) of the upgraded bio-oil. The catalyst type affected the yields of the product fractions: SAPO-11 produced the lowest upgraded bio-oil yield of 42.4 wt.%, and MCM-41 provided the highest yield of 54.5 wt.%. Compared with non-catalytic upgrading reactions, all of the zeolites promoted the denitrogenation, deoxygenation, and desulfurization of the pretreated bio-oil due to the presence of acid sites. HY (5% Na2O), HY (0.8% Na2O), and HZSM-5 (SiO2/Al2O3  = 25:1) showed the highest activity toward denitrogenation, deoxygenation, and desulfurization, respectively. The upgraded bio-oil mainly consisted of hydrocarbons, accounting for 80% in total and as high as 95.6% of the fraction below 400 °C.
Keywords: Microalgae; Hydrothermal liquefaction; Pretreatment; Upgraded; Zeolites; Upgraded bio-oil;

Building a predictive model for PHB production from glycerol by Cristina Pérez Rivero; Chenhao Sun; Constantinos Theodoropoulos; Colin Webb (113-121).
Poly-3-hydroxybutyrate (PHB) is a biodegradable biopolyester with plastic like properties, which on its own or as part of a heteropolymer, finds application in everyday products, competing directly with fossil fuel based plastics in terms of physical and mechanical properties. In nature, PHB is produced as an energy reservoir for the host cell, when environmental conditions limit growth. It is this inherent condition for PHB synthesis (i.e. an environment unsuitable for growth) that challenges design of conventional batch production systems. Balance between growth (driven by nitrogen availability) and PHB production (enhanced by an excess of carbon) is the critical aspect for consideration in such designs. However, selecting the best operating conditions is not obvious for this system and so a systematic approach has been used in this paper, utilising simulations based on a purpose built model to supplement experimental studies.The interaction between the carbon and nitrogen sources (glycerol and ammonium sulphate respectively) was carefully evaluated and incorporated into a low-structured model able to describe the dynamics of substrate consumption and product accumulation during Cupriavidus necator DSM 545 cultivation at small scale. The kinetic parameters thus determined have been assumed to be constant, fixed accordingly, and the model used to predict the fermentation profiles for different operating conditions. Results showed good agreement with experimental data, supporting the efficacy of this approach. The dual utilization of multiple substrates suggests there is a system capacity to which both growth and PHB production contribute and that sets the maximum total biomass concentration. A logistic type term added to both growth and product rate equations enabled the effective decoupling of cell proliferation and PHB accumulation for a wide range of scenarios. In this way, the combination of predictive modelling and experimental verification potentially reduces, by a significant amount, the number of experiments required to establish operational targets such as specific growth rate and productivity as well as identifying often sought criteria such as optimum C:N ratio.
Keywords: Biorefinery; Intracellular polymer; Predictive modelling; Growth kinetics; Production kinetics; Dual substrate model;

Design strategies for sustainable biorefineries by Jonathan Moncada B.; Valentina Aristizábal M.; Carlos A. Cardona A. (122-134).
The biorefinery concept is considered as one of the research cornerstones in the last years and as the best option to transform the different biomass systems into value-added products. A review about different approaches related to the modelling and assessment of biorefineries is presented taking into account raw materials, technologies, processing routes, products, and technical, economic and environmental aspects. Methodologies for biorefineries design as conceptual design, optimization and early-stage approaches are studied. Three main concepts are analyzed for the conceptual design of biorefinery systems: hierarchy, sequencing and integration. Finally, the proposed strategy for biorefinery synthesis is applied briefly to two previously cases developed by the authors. A mass index as a new basic concept is applied for understanding the biorefinery efficiency in terms of processing biomass.
Keywords: Biorefinery concept; Biorefinery design; Mass index of biorefineries;

A mathematical programming formulation for biorefineries technology selection by Nikolaos Bonatsos; Endrit Dheskali; Denise M.G. Freire; Aline Machado de Castro; Apostolis A. Koutinas; Ioannis K. Kookos (135-145).
Display OmittedSystematic methods, such as mathematical programming methods, are traditionally used in decision making concerning capacity planning, especially at tactical and operational level. However, such methods might have the greatest impact at the strategic level where substantial resources are irreversibly allocated. This study proposes a mathematical programming methodology to assist decision makers in strategic (long term) planning for bioprocessing of renewable resources. The novelty lies on the incorporation of significant detail of the bioprocess design in the strategic model and the use of a relatively accurate model for estimating the cost of manufacture of the alternative bioprocesses. A case study demonstrates the advantages of the proposed systematic methodology focusing on optimal screening of 25 bioprocesses for the conversion of molasses, sucrose and glycerol into 11 metabolic products. The methodology was validated via preliminary techno-economic evaluation of the optimum technology-mix involving the production of succinic acid, poly(3-hydroxybutyrate) and 2,3-butanediol.
Keywords: Bioprocess design; Optimisation; Biorefinery development; Poly-(3-hydroxybutyrate); Succinic acid; 2,3-Butanediol;

The need to achieve a sustainable process performance has become increasingly important in order to keep a competitive advantage in the global markets. Development of comprehensive and systematic methods to accomplish this goal is the subject of this work. To this end, a multi-level framework for techno-economic and environmental sustainability analysis through risk assessment is proposed for the early-stage design and screening of conceptual process alternatives. The alternatives within the design space are analyzed following the framework’s work-flow, which targets the following: (i) quantify the economic risk; (ii) perform the monetary valuation of environmental impact categories under uncertainty; (iii) quantify the potential environmental risk; (iv) measure the alternatives’ eco-efficiency identifying possible trade-offs; and, lastly (v) propose a joint risk assessment matrix for the quantitative and qualitative assessment of sustainability at the decision-support level. Through the application of appropriate methods in a hierarchical manner, this tool leads to the identification of the potentially best and more sustainable solutions. Furthermore, the application of the framework is highlighted by screening two conceptual glycerol bioconversion routes to value-added chemicals namely 1,3-propanediol (1,3-PDO) and succinic acid.
Keywords: Conceptual process; Techno-economic assessment; Environmental assessment; Uncertainty analysis; Glycerol biorefinery;

Techno-economic evaluation of wine lees refining for the production of value-added products by Charalampia Dimou; Anestis Vlysidis; Nikolaos Kopsahelis; Seraphim Papanikolaou; Apostolis A. Koutinas; Ioannis K. Kookos (157-165).
The cost-competitiveness of a refining process using wine lees for the production of ethanol, antioxidant-rich extract, calcium tartrate and yeast cells was evaluated in this study via process design and preliminary techno-economic evaluation. Process design was performed using the commercial process simulator UniSim (Honeywell). A sensitivity analysis was carried out to estimate the minimum selling price of the antioxidant-rich extract that should be achieved at different plant capacities in order to develop a profitable wine lees refining process. Minimum selling prices of the antioxidant-rich extract in the range of 122–11.06 $/kg are required in order to develop profitable refining schemes with wine lees processing capacities of 500 to 5000 kg/h considering 120 days of annual operating time. The final products could be used in various industrial segments including food, feed, chemical and cosmetic industries.
Keywords: Wine lees valorisation; Biorefinery; Integrated processing; Process design; Techno-economic evaluation;

Design and optimization of intensified biorefinery process for furfural production through a systematic procedure by Le Cao Nhien; Nguyen Van Duc Long; Sangyong Kim; Moonyong Lee (166-175).
Display OmittedFurfural, which is used as a precursor for the production of many other industrial chemicals, has been identified as one of the major bio-based platform chemicals that can compete with petroleum-based chemicals. On the other hand, the current commercial furfural process has a low yield and is energy-intensive. Therefore, this study develops the biorefinery production process of furfural from lignocellulosic biomass using process heat integration and process intensification. In particular, a distillation unit of the furfural production process requires considerable energy, highlighting the need to improve energy efficiency, which is the motivation of this work. An integrated and intensified distillation sequence, including an innovative bottom dividing wall column with a decanter configuration (BDWC-D) was suggested to enhance the energy and cost efficiency of the furfural production process through a comprehensive and systematic procedure that combines process intensification with heat integration. The structures of the complex columns in all sequences were optimized using the optimization method-response surface methodology (RSM). All simulations were conducted using Aspen HYSYS. The results show the proposed sequence can reduce total annual cost and carbon footprint by 10.1% and 11.6%, respectively compared to the conventional sequence.
Keywords: Biorefinery development; Large-scale furfural process; Dividing wall column; Process integration and intensification; Bioprocess design; Bioprocess optimization;

A process integration approach for the production of biological iso-propanol, butanol and ethanol using gas stripping and adsorption as recovery methods by Konstantinos A. Pyrgakis; Truus de Vrije; Miriam A.W. Budde; Kyriakos Kyriakou; Ana M. López-Contreras; Antonis C. Kokossis (176-194).
Biomass fermentation to Iso-propanol, Butanol and Ethanol (IBE) is particularly important as IBE is a common building block in the development of biorefineries and IBE-producing bacteria are robust industrial organisms, capable to utilize the sugars of the lignocellulosic biomass. Research is focused on increasing fermentation yields and the reduction of energy that is required to separate the volatile products. The paper addresses both of these challenges combining experimental innovations with a systems engineering approach. IBE is recovered from a gas-stripped fermenter whose potential for adsorption is researched and integrated with downstream options for separation. Design and integration is assisted using a systems approach that relies on mathematical models that regress and extrapolate experimental data for scale-up calculations. Process integration involves synthesis challenges to define biorefinery portfolios and systems integration to combine fermentation, stripping, adsorption, and distillation. The analysis considers 4 alternative biorefinery cases and presents results with significant savings in energy use and costs (up to 87% savings reported) after the application of energy integration to the IBE plant. Scenarios are analysed economically and confirm benefits in the use of adsorption and viable production yields.
Keywords: Iso-propanol, Butanol, Ethanol Fermentation; In-situ product removal; Gas stripping; Adsorption; Mathematical modelling and process design; Process integration;

The bio-based n-butanol has major potential to replace fossil-based products due to, on the first hand, the decline of crude oil and, on the other hand, since the butanol has high potential as fuel. To set its production in industrial scale the development of tools designing the process is needed. In our work, we focus on second generation biorefinery using wood as feedstock. The biorefinery was composed by the pretreatment, the hydrolysis, the fermentation, the butanol recovery and the purification. The proposed methodology is a multiscale decision support tool for the selection of the optimal process design of the biorefinery producing biobutanol. The optimal biorefinery is selected from the superstructure recapping all feasible scenarios after process modelling and simulation, economic and environmental evaluations and energy integration. Thus, the optimal process is profitable, efficient and sustainable. Moreover, to identify the influence of the biobutanol recovery on the fermentation’s performances, the process modelling includes the retroaction of biobutanol recovery. In this study, three biobutanol recovery and four purification scenarios are combined and then processes are compared to select the optimal biorefinery for the bio based butanol production.
Keywords: Bioprocess design; Downstream processing; Modelling; Process integration; Optimal design; Biobutanol;