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The Proportion of Downstream Costs in Fermentative Production Processes
Abstract
Statements in the literature about the contribution of downstream processing (DSP) to production costs are often exaggerating and usually not supported by proper documentation. Therefore, published process data were evaluated. For biopharmaceuticals, it is fair to state that DSP costs generally dominate production costs, but for bulk fermentation products the available process data indicate a range of only 20–40%. For these bulk products, the main costs are upstream, and for 15–60% due to carbohydrate purchase costs.
... The costs of downstream processing contribute significantly to the overall production costs. Here, the capital investment and operational costs for each unit operation as well as the overall efficacy to recover the product from the cultivation broth need to be considered [20,21]. Due to its polar-nonpolar-polar structure, astaxanthin is incorporated into the cell membrane [22] or stored intracellularly within lipid droplets [23], depending on the organism. ...
... In order to meet the growing market demand as well as consumer requirements for natural astaxanthin, the industrial workhorse C. glutamicum has been engineered to produce astaxanthin [36,37]. To be economically competitive, not only must the bacterial cultivation be optimized, but also the downstream process for product recovery [20,21]. The recovery of astaxanthin is particularly challenging as the molecule is incorporated within the biomass [22,23], as well as being susceptible to heat, light and oxygen [44]. ...
... Mar. Drugs 2023,21, 530 ...
The marine carotenoid astaxanthin is one of the strongest natural antioxidants and therefore is used in a broad range of applications such as cosmetics or nutraceuticals. To meet the growing market demand, the natural carotenoid producer Corynebacterium glutamicum has been engineered to produce astaxanthin by heterologous expression of genes from the marine bacterium Fulvimarina pelagi. To exploit this promising source of fermentative and natural astaxanthin, an efficient extraction process using ethanol was established in this study. Appropriate parameters for ethanol extraction were identified by screening ethanol concentration (62.5–97.5% v/v), temperature (30–70 °C) and biomass-to-solvent ratio (3.8–19.0 mgCDW/mLsolvent). The results demonstrated that the optimal extraction conditions were: 90% ethanol, 60 °C, and a biomass-to-solvent ratio of 5.6 mgCDW/mLsolvent. In total, 94% of the cellular astaxanthin was recovered and the oleoresin obtained contained 9.4 mg/g astaxanthin. With respect to other carotenoids, further purification of the oleoresin by column chromatography resulted in pure astaxanthin (100%, HPLC). In addition, a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay showed similar activities compared to esterified astaxanthin from microalgae and a nine-fold higher antioxidative activity than synthetic astaxanthin.
... Product recovery and purification is a very important aspect to consider for commercialisation of a chemical product. Downstream processes contribution to the total cost of the final product are comprised between the 20 and 60% (Hoppe et al., 2015;Straathof, 2011). Moreover, 3-HP recovery from bioconversion media at high concentration and purity is particularly challenging. ...
... The overall cost of microbial production is dominated by feedstock cost and downstream processing. In particular, downstream processes contribution represents between 20 and 60% of the selling price (Djas and Henczka, 2018;Straathof, 2011). ...
... La récupération et la purification des produits est un aspect très important à considérer pour la commercialisation d'un produit chimique. La contribution des procédés en aval au coût total du produit final se situe entre 20 et 60% (Hoppe et al., 2015 ;Straathof, 2011). De plus, la récupération du 3-HP de milieux de bioconversion à haute concentration et pureté est particulièrement difficile. ...
La sensibilisation croissante au changement climatique a suscité l’intérêt des industries pour réduire leur dépendance aux matières premières d’origine fossile. Dans le cas de l'industrie chimique, cela a augmenté la demande de produits chimiques bio-sourcés, ce qui a déclenché le développement de procédés biotechnologiques innovants et plus sobres. L'acide 3 hydroxypropionique (3-HP) est une molécule plateforme qui peut être produite à partir de la biomasse et peut être convertie en une large gamme de composés chimiques utilisés dans l'industrie des matériaux bio-sourcés comme le poly(3-hydroxypropionate) et les dérivés d’acrylates. L’obtention de 3-HP par voie microbiologique a connu des progrès remarquables, mais sa production commerciale est encore limitée par les faibles productivités dues à la retro-inhibition des microorganismes par leurs produits et des difficultés de récupération et de purification. Couplée en ligne à la bioconversion, l'extraction réactive assistée par un contacteur membranaire, également connue sous le nom de pertraction réactive, est une stratégie prometteuse pour lever les phénomènes d’inhibition et intensifier la bioconversion du 3-HP. Plusieurs verrous restent cependant à lever. Ce travail vise à élucider certains aspects clés pour la conception et la conduite d'un tel procédé intégré. Tout d'abord, le système d'extraction réactive a été étudié à l'échelle de l’interface liquide-liquide en combinant la mesure expérimentale à la modélisation de la tension interfaciale dynamique (IFT) pendant l'extraction du 3-HP, afin de mieux comprendre les mécanismes limitants. Il a été constaté que le transfert de matière près de l'interface n'était pas régi seulement par la diffusion moléculaire, ce qui suggère que des phénomènes tels que les gradients de densité induits par la concentration et les forces de flottabilité associées, ou les gradients de tension interfaciale induits par la concentration et la convection de Marangoni associée, peuvent également jouer un rôle important. Une méthodologie complète pour la sélection d'une composition de phase organique, basée à la fois sur la performance d'extraction et la biocompatibilité avec une souche productrice de 3-HP, Lactobacillus reuteri DSM 17938, a également été développée. L'effet de la nature et de la concentration des solvants sélectionnés a été évalué et a souligné l'importance de trouver un compromis entre le rendement d'extraction, la viscosité et la biocompatibilité par rapport à la souche microbienne utilisée. Enfin, l'intégration de la pertraction réactive avec la bioconversion a été réalisée. Deux souches différentes produisant le 3-HP, L. reuteri DSM 17938 et Acetobacter sp. CIP 58.66, ont été utilisées. Il a été observé que L. reuteri est très sensible aux conditions de pertraction réactive. De plus, le pH de bioconversion n'était pas compatible avec les exigences d'une extraction réactive performante du 3-HP. Dans l'ensemble, la production et l'extraction de 3-HP étaient très limitées lors de cette tentative d'intégration mettant en œuvre L. reuteri. D'autre part, la bioconversion extractive avec Acetobacter sp. a permis d'obtenir de meilleures performances. L'approche intégrée n’a pas réduit significativement les capacités de production élevées de la souche, qui a montré une bonne résistance aux stress cumulés, ce qui en fait un excellent candidat pour la bioconversion extractive. Cependant, un déséquilibre important entre les taux de production et d'extraction a été mis en évidence, entraînant une diminution du pH pendant la production de 3-HP, mais cela a eu un impact limité sur la capacité de bioconversion d'Acetobacter sp. D'autres stratégies d'optimisation ont été explorées en utilisant un modèle mathématique comme outil de simulation. Les informations obtenues tout au long de ce travail ouvrent la voie à la conception d'un procédé intégré de production de 3-HP bio-sourcé intensifié.
... Separation methods like solvent extraction, distillation, pervaporation, electrodialysis, reactive extraction and many others are the options for PA separation. The downstream processing (DSP) in these industries contributes to 30-40% of the total production cost (10). Any such separation techniques need to reduce this cost. ...
... Devices like mixer settler cascades, tray column, packed column in some cases, rotating disk contactors, centrifugal extractors and many others are included in them. The problems associated with this type of equipment include non-uniform size distribution of liquid/gas drops, poor mixing behaviour, low surface to volume ratio, low heat and mass transfer coe cients, and so on (López-Garzón & Straathof, 2014, Straathof et al., 2011, Gentry & Solazzo, 1995. Microchannels have been proved to be effective devices for conducting solvent extraction processes. ...
Solvent extraction is an important industrial operation where several stages are needed for a desired separation. Microchannel based solvent extraction is widely reported for process intensification. However, all these works are confined to a single-stage extraction till date. For industrial application knowledge of multistage extraction is mandatory. This work focuses on the multistage microchannel extraction using a model mixture containing aqueous propionic acid. Four different single solvents were employed in this study hexane, toluene, heptane, and cyclohexanol. The Effect of flow rate, flow ratio on percentage extraction, extraction efficiency, and the required number of stages was investigated. The number of stages required for the maximum recovery of PA from the raffinate is 5 for hexane &heptane and 3 for toluene and 2 for cyclohexanol. The percentage extraction of solvents obtained overall through all the stages is, cyclohexanol, 57–89%, toluene, 35–50%, heptane, 27–51%, and hexane 19-31.3%. Cyclohexanol produced the maximum percentage extraction. The extraction efficiency and the volumetric mass transfer coefficient decreased with the stage numbers. The maximum extraction efficiency for all the solvents is in the range of 98-99.8%. A microchannel stack is found to reduce the total annual cost (TAC). Particularly, fabrication in India results in very less capital cost for the microchannels i.e.1.9–14.3% of TAC. The total annual cost analysis of toluene is the minimum than other solvents.
... In the downstream purification process from organic acid production using fermentation, various methods have exhibited different characteristics, advantages, and disadvantages, and different levels of purification efficiency and purity that depends on the products (Li et al., 2021;Magalhães et al., 2017). The recovery cost of IA from fermentation broth accounts for a large proportion, about 40%, of the total cost (Straathof, 2011). Therefore, the development of high efficiency and low-cost processes for organic acid recovery is essential for replacing petrochemical-based products (López-Garzon & Straathof, 2014). ...
... Improved downstream processing for the separation and purification of fermentation products is also critical to developing cost effective processes using lignocellulosic biomass. In a case, the recovery cost of organic acid from fermentation broth accounts for 40% of the total cost (Straathof, 2011). Adsorption and electrodialysis have an advantage in downstream processing since these processes do not require the addition of hazardous chemicals (Delgado et al., 2018;Komáromy et al., 2020). ...
Lignocellulosic biomass has great potential as an inedible feedstock for bioplastic synthesis, although its use is still limited compared to current edible feedstocks of glucose and starch. This review focuses on recent advances in the production of biopolymers and biomonomers from lignocellulosic feedstocks with downstream processing and chemical polymer syntheses. In microbial production, four routes composed of existing poly (lactic acid) and polyhydroxyalkanoates (PHAs) and the emerging biomonomers of itaconic acid and aromatic compounds were presented to review present challenges and future perspectives, focusing on the use of lignocellulosic feedstocks. Recently, advances in purification technologies decreased the number of processes and their environmental burden. Additionally, the unique structures and high-performance of emerging lignocellulose-based bioplastics have expanded the possibilities for the use of bioplastics. The sequence of processes provides insight into the emerging technologies that are needed for the practical use of bioplastics made from lignocellulosic biomass.
... The costs of purification (downstream processing; DSP) depend on the required product specification. A DSP share of 20-40% of the total COGS of platform chemicals (technical grade) was reported; for functionalised, added-value products like biopharmaceuticals (pharma-grade) even higher [66]. With regard to conversion costs, the product-specific yield must also be taken into account; an overview is provided by Agrawal et al. (2023) [67]. ...
As the raw material transition from fossil to renewable feedstock progresses, the demand for biogenic raw materials for industrial purposes will increase. This applies above all to the energy and chemical sectors. However, the capacities for biogenic energy and carbon sources to be provided by agriculture and forestry are limited. This review examines the contribution that biogenic raw materials and CO2 from biogenic sources can make to sustainable chemical production in the EU. It analyses statistical data from the EU and studies from the chemical industry. First priority needs to be given to edible biomass for the sector of nutrition. When it comes to the industrial use of biomass, sectors should be prioritised that cannot do without carbon-supplying raw materials. This is particularly the case in the field of organic chemistry. This review focuses on bio-based organic chemical products and gives an outlook on the future of chemical production in Europe based on primary, secondary, and tertiary biomass and CO2 from biogenic sources. Finally, two new indicators for economically and ecologically sustainable industrial use of biomass are proposed. Both indicators can support the determination of the sustainability status of the sustainable integration of agriculture, forestry, residual, and biowaste management in bioeconomic value networks.
... The latter usually accounts for a large proportion of the process costs, reaching 30-40 % of the selling price for citric acid, and up to 50 % of the production costs for lactic acid. Additionally, during lactic acid production, up to one ton of gypsum (CaSO 4 ) per ton of product is generated, which is often landfilled and can generate additional disposal costs [14][15][16][17][18][19]. ...
Reactive liquid–liquid extraction is an attractive, innovative technique to intensify the fermentative production and downstream processing of biobased organic acids through a selective partitioning to an organic phase. In an in situ product recovery (ISPR) approach, fermentation performance can be enhanced by alleviating product inhibition, yielding a relatively concentrated product stream. While reactive extraction has been widely studied for different organic acids in dilute aqueous solutions, its application to complex product streams from fermentation brings important added challenges. This review addresses these challenges and offers perspectives for future research and scale-up studies towards industrialisation. The complex interplay of solvent systems, extraction behaviour of different organic acids, and fermentation-dependent parameters is critically reviewed. Additionally, challenges faced upon implementation in industrial set-ups are discussed with a specific focus on ISPR technologies, discussing back extraction and resource recycling, as well as techno-economic considerations. To that end, potential process strategies and future research directions are proposed to overcome remaining limitations to bring this technology to an industrial level.
... In unbuffered conditions, concentrations as low as 5 g/L ccMA caused a significant reduction of 43% in the maximum specific growth rate of the laboratory reference strain S. cerevisiae CEN.PK 113-7D [13]. Despite this, low-pH fermentation remains attractive, as medium neutralization requires high amounts of acids and bases, typically resulting in significant salt waste, and can therefore compromise economic feasibility [14,15]. ...
The efficient production of biobased organic acids is crucial to move to a more sustainable and eco-friendly economy, where muconic acid is gaining interest as a versatile platform chemical to produce industrial building blocks, including adipic acid and terephthalic acid. In this study, a Saccharomyces cerevisiae platform strain able to convert glucose and xylose into cis,cis-muconic acid was further engineered to eliminate C2 dependency, improve muconic acid tolerance, enhance production and growth performance, and substantially reduce the side production of the intermediate protocatechuic acid. This was achieved by reintroducing the PDC5 gene and overexpression of QDR3 genes. The improved strain was integrated in low-pH fed-batch fermentations at bioreactor scale with integrated in situ product recovery. By adding a biocompatible organic phase consisting of CYTOP 503 and canola oil to the process, a continuous extraction of muconic acid was achieved, resulting in significant alleviation of product inhibition. Through this, the muconic acid titer and peak productivity were improved by 300% and 185%, respectively, reaching 9.3 g/L and 0.100 g/L/h in the in situ product recovery process as compared to 3.1 g/L and 0.054 g/L/h in the control process without ISPR.
... Some of the nutrients are usually composed of inorganic salts, such as phosphates or nitrates. After the enzymatic phase, downstream separation and purification steps are needed to reach a final marketable product; these steps being key contributors to the overall process costs [6,7]. The most common process for citric acid recovery and purification is based on precipitation, where calcium hydroxide and sulfuric acid are added to obtain the final product. ...
Electrodialysis is finding an increasing number of applications, recently also in the separation and purification of organic acids. This technology involves reducing the use of chemicals and the generation of wastes, as compared to conventionally used processes. Gaining insights about the competitive transport between organic and inorganic ions in ED systems is key to achieving efficient separation processes in the bioresource industry. In the present study, the competitive transport of organic (citrates) and inorganic anions (nitrates) through anion-exchange membranes is investigated, under varying pH conditions, ion concentrations, and applied currents, by means of chronopotentiometry and ED experiments. In the absence of nitrate ions and under acidic conditions (pH 2), the resistance of the membrane system is very high because citric acid is mainly present in its undis-sociated and uncharged form. In the case of sodium citrate (pH 8), the membrane resistance decreases, especially at high current densities, which promote dissociation reactions and the subsequent concentration increase in ionic species near the membrane. Such phenomenon is identified both in chronopotentiometric curves and in long-term ED experiments by a gradual drop in membrane voltage with time. Although being less concentrated than citrates, the selective removal of nitrates is the most effective choice for the separation of both types of species. The selectivity factor of nitrates over citrates reaches the highest values at low applied current densities (below the limiting current density), with stable permselectivity values higher than 20. Such conditions also lead to the least specific energy consumption per nitrates removed (<0.5 kW⋅hr⋅kg NO−3−1). Therefore, ED can be used under such favorable operating conditions after a clarification step in order to remove inorganic ions from fermentation broths and increase the purity of organic acids. At higher current densities, the enhanced transport of citrate anions produces a significant drop in selectivity towards nitrates and increases the specific energy consumption.
... 12 Accordingly, the costs related to the downstream processing can considerably contribute to the total production costs (20-40%). 13 For example, the purification costs of ethanol and butanol were estimated to be about 21-29% [14][15][16][17] (recovery by azeotropic distillation, 14 distillation coupled with molecular sieves, 15,16 pressure-swing distillation 17 ) and 40% 18 (recovery by distillation) of the total production costs. Therefore, significant improvements in downstream processing are needed to increase the competitiveness and viability of industrial fermentation technologies. ...
Even though industrial biotechnology is successfully used for the production of some chemicals, for many other chemicals it is not yet competitive with conventional petrochemical production. Usually, fermentation as well as downstream processing requires improvement. Downstream processing has to deal with low product concentrations, microorganisms, impurities and thermodynamic constraints (e.g., azeotropes), which often makes it very challenging and expensive, especially on a large scale. However, downstream processing of biochemicals has not attracted as much attention as upstream fermentation processes. In that context, this perspective paper offers a lightly referenced scholarly opinion about the downstream processing performance of different bioalcohols after fermentation. Due to the stronger toxicity effects on microbes, the achievable concentrations of monohydric aliphatic alcohols in the fermentation broth decrease with the increasing chain length. Specifically, the concentrations used here are 6.14, 5.00, 1.61 and 0.24 wt% of ethanol, isopropanol, isobutanol and hexanol, respectively. More dilute fermentation broths lead to more complex recovery processes. According to our previous work, the total purification costs increase from 0.080 USD kg⁻¹ for ethanol, 0.109 USD kg⁻¹ for isopropanol and 0.161 USD kg⁻¹ for isobutanol to 0.529 USD kg⁻¹ for hexanol. A similar trend is noticeable for the energy usage (0.960, 1.348, 2.018 and 3.069 kWthh kg⁻¹, respectively) and the related CO2 emissions (0.164, 0.221, 0.449 and 0.555 kgCO2 kg⁻¹, respectively). This work shows that advanced separation and purification based on process intensification principles are crucial for overall efficient production processes. The achievable product concentration in the fermentation broth – and not so much the alcohol chain length – has the biggest influence on the performance of downstream processing. Therefore, simultaneous development of both upstream and downstream processing is necessary to ensure the competitiveness and viability of industrial fermentation processes. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
... 13 The downstream processing cost for penicillin G is about 50 to 55% when purified and formulated. 14 To overcome these challenges, an adsorption based recovery approach has been developed for compounds such as lactic acid, 15 antibiotics like cephalosporin, geldanamycin, tetracycline, 16−18 and many more as these methods are effective and relatively inexpensive. ...
Penicillin V (phenoxy methyl penicillin) is highly sought after among natural penicillins because of its exceptional acid stability and effectiveness against common skin and respiratory infections. Given its wide-ranging therapeutic uses, there is a need to establish a greener method for its maximum recovery to reduce the carbon footprint. Here, we have identified and validated optimized operational conditions for resin-based penicillin V recovery. It was observed that Amberlite XAD4 had the highest penicillin V hydrophobic adsorption capacity among the other screened resins. Kinetic and isothermal studies using linear and nonlinear regression analysis showed that the adsorption process well fitted with pseudo-second-order kinetics (R² = 0.9816) and the Freundlich adsorption isotherm model (R² = 0.9871). Adsorption equilibrium was attained within 4 h, while maximum adsorption was observed at 3 mg/mL penicillin V concentration. Furthermore, the optimized extraction protocol was compared with the conventional butyl acetate-based downstream processing. Under optimum conditions resin-based penicillin V recovery was 2-fold higher as compared to the solvent extraction method and the resin could be reused for over six cycles without compromising the yield. These findings signify substantial progress toward the development of an environmentally sustainable approach for penicillin V recovery and a potentially viable method for extractive fermentation.
... The overarching theme, therefore, is patient access and how we can help ensure access and extend it to low-and middle-income countries (LMICs). Downstream processing plays an important role in the supply of pharmaceuticals and, in particular, biopharmaceuticals, where a large proportion of the production costs are attributable to the recovery and purification processes (Straathof, 2011) although this may have shifted to upstream processes in the case of cell and gene therapy manufacturing (Comisel et al., 2021) while DSP for these new modalities have very low yields, with some unit operations having yields as low as 20% while scale-up can cause a significant drop in yield (Perry & Rayat, 2021). ...
Governments and biopharmaceutical organizations aggressively leveraged expeditious communication capabilities, decision models, and global strategies to make a COVID‐19 vaccine happen within a period of 12 months. This was an unusual effort and cannot be transferred to normal times. However, this focus on a single vaccine has also led to other treatments and drug developments being sidelined. Society expects the pharmaceutical industry to provide an uninterrupted supply of medicines. However, it is often overlooked how complex the manufacture of these compounds is and what logistics are required, not to mention the time needed to develop new drugs. The overarching theme, therefore, is patient access and how we can help ensure access and extend it to low‐ and middle‐income countries. Despite unceasing efforts to make medications available to all patient populations, this must never be done at the expense of patient safety. A major fraction of the costs in biopharmaceutical manufacturing are for drug discovery, process development, and clinical studies. Infrastructure costs are very difficult to quantify because they often depend on whether a greenfield facility or an existing, depreciated facility is used or adapted for a new product. To accelerate process development concepts of platform process and prior knowledge are increasingly leveraged. While more traditional protein therapeutics continue to dominate the field, we are also experiencing the exciting emergence and evolution of other therapeutic formats (bispecifics, tetravalent mAbs, antibody‐drug conjugates, enzymes, peptides, etc.) that offer unique treatment options for patients. Protein modalities are still dominant, but new modalities are being developed that can be learned from including advanced therapeutics‐like cell and gene therapies. The industry must develop a model‐based strategy for process development and technologies such as continuous integrated biomanufacturing must be adopted. The overall conclusion is that the pandemic pace was unsustainable, focused on vaccine delivery at the expense of other modalities/disease targets, and had implications for professional and personal life (work‐life balance). Routinely reducing development time from 10 years to 1 year is nearly impossible to achieve. Environmental aspects of sustainable downstream processing are also described.
... The stability appears to be associated with the replication gene and may be ensured by host cell factors. In bulk chemical production, fermentation costs are an important factor in profitability (Straathof, 2011) and the ability to dispense antibiotics for production may be a factor favouring the use of pZMO7-derived backbones over other plasmids in industrial applications of Z. mobilis. However, plasmid stability will be influenced by the metabolic burden the construct imposes on the cells and needs to be checked for the specific application. ...
Zymomonas mobilis has the potential to be an optimal chassis for the production of bulk chemicals derived from pyruvate. However, a lack of available standardized and characterized genetic tools hinders both efficient engineering of Z. mobilis and progress in basic research on this organism. In this study, a series of different shuttle vectors were constructed based on the replication mechanisms of the native Z. mobilis plasmids pZMO1, pZMOB04, pZMOB05, pZMOB06, pZMO7 and p29191_2 and on the broad host range replication origin of pBBR1. These plasmids as well as genomic integration sites were characterized for efficiency of heterologous gene expression, stability without selection and compatibility. We were able to show that a wide range of expression levels could be achieved by using different plasmid replicons. The expression levels of the constructs were consistent with the relative copy numbers, as determined by quantitative PCR. In addition, most plasmids are compatible and could be combined. To avoid plasmid loss, antibiotic selection is required for all plasmids except the pZMO7‐based plasmid, which is stable also without selection pressure. Stable expression of reporter genes without the need for selection was also achieved by genomic integration. All modules were adapted to the modular cloning toolbox Zymo‐Parts, allowing easy reuse and combination of elements. This work provides an overview of heterologous gene expression in Z. mobilis and adds a rich set of standardized genetic elements to an efficient cloning system, laying the foundation for future engineering and research in this area.
... However, to the best of our knowledge, downstream processing of volatile biochemicals 88 on large-scale is not that well studied. Since purification costs for bulk biochemicals can significantly 89 add to the total production costs (up to 20-40%) (Straathof, 2011), this paper focuses on the best 90 ways to enhance the overall economic viability of volatile biochemical production by improving 91 downstream processing. Besides reducing the total production costs, advanced downstream 92 processing can reduce the overall energy requirements, greenhouse gas emissions and water 93 ...
Due to lower environmental impact, biochemicals are rapidly gaining significance as a potential renewable solution, particularly of interest in Europe. In this context, process systems engineering (PSE) helps with the decision-making at multiple scales and levels, aiming for optimum use of (renewable) resources. Fermentation using waste biomass or industrial off-gases is a promising way for the production of these products. However, due to the inhibitory effects or low substrate concentrations, relatively low product concentrations can be obtained. Consequently, significant improvements in downstream processing are needed to increase the competitiveness of the overall bioprocesses. This paper supports sustainable development by providing new PSE perspectives on the purification of volatile bioproducts from dilute fermentation broths. Since purification significantly contributes to the total cost of biochemical production processes (20-40% of the total cost), enhancing this part may substantially improve the competitiveness of the overall bioprocesses. The highly advanced downstream process offers the possibility of recovering high-purity products while enhancing the fermentation step by continuously removing inhibitory products, and recycling microorganisms with most of the present water. Besides higher productivity, the upstream process can be greatly improved by avoiding loss of biomass, enabling closed-loop operation and decreasing the need for fresh water. Applying heat pumping, heat integration and other methods of process intensification (PI) can drastically reduce energy requirements and CO 2 emissions. Additionally, the opportunity to use renewable electricity instead of conventional fossil energy presents a significant step toward (green) electrification and decarbonization of the chemical industry.
... More than 96% of these figures are accounted for by protein therapeutics, which are set apart from other applications by their stringent purity requirements and the associated high costs of manufacturing. For such drugs, manufacturing costs typically represent approximately 20% of total sales (Decker et al., 2020) and downstream processing typically represents about 75% of total manufacturing costs (Straathof, 2011). Therefore, protein purification processes alone cost more than $40 billion per year. ...
For protein drug purification, packed-bed chromatography often remains both the predominant method and a bottleneck for cost and scalability. Accordingly, extensive efforts have been made to develop alternatives, such as precipitation and liquid-liquid extraction. Despite decades of development, such methods have been slow to see adoption in commercial processes. To diagnose the key barriers to implementation and guide future work, we have systematically reviewed studies of protein precipitation and liquid-liquid extraction. We classify the products, methods, and results of 168 publications representing 290 unique purification operations and analyze these operations in terms of both process economics and purification performance. Whereas it is generally assumed that precipitation and extraction methods will have lower costs than chromatography, we find that this is only the case under specific process conditions such as at a large manufacturing scale and low initial sample purity. Furthermore, we find that only a small number of the many precipitation and extraction methods reported to date have shown readiness for implementation in protein drug purification processes. Finally, we identify key factors governing both the economic and purification performance of this class of methods: first, that operating costs are almost entirely predictable by the ratio between the mass of phase-forming materials used and the mass of product protein yielded; second, that use of modern optimization techniques such as Design of Experiments is associated with significantly better purification performance and cost-effectiveness.
Highlights
Alternative separation purification methods are not always cheaper than chromatography
The use of a combination of phase separating agents remains largely underexplored/underutilized
Lower initial purity and increasing production scale favor phase-separation over chromatography
The direct material usage rate is an important predictor of alternative separation cost-effectiveness
Current alternative separation method development has largely ignored optimization of direct material usage rate
... Our primary objective was to develop a P. pastoris strain capable of efficiently producing and secreting free fatty acids, especially palmitoleic acid (POA), using glucose as the carbon source. The efficient secretion of fatty acids is of particular significance, as it streamlines downstream processing, which often constitutes a substantial portion of the production costs in biotechnological applications [53]. To achieve fatty acid secretion, we implemented the following engineering steps: (i) deletion of acyl-CoA synthetases, (ii) overexpression of heterologous thioesterases, (iii) enhancement of precursor supply, and (iv) alleviation of competing pathways in accordance with the push-pull block theorem commonly employed in metabolic engineering [54]. ...
Fatty acids have been supplied for diverse non-food, industrial applications from plant oils and animal fats for many decades. Due to the massively increasing world population demanding a nutritious diet and the thrive to provide feedstocks for industrial production lines in a sustainable way, i.e., independent from food supply chains, alternative fatty acid sources have massively gained in importance. Carbohydrate-rich side-streams of agricultural production, e.g., molasses, lignocellulosic waste, glycerol from biodiesel production, and even CO2, are considered and employed as carbon sources for the fermentative accumulation of fatty acids in selected microbial hosts. While certain fatty acid species are readily accumulated in native microbial metabolic routes, other fatty acid species are scarce, and host strains need to be metabolically engineered for their high-level production. We report the metabolic engineering of Pichia pastoris to produce palmitoleic acid from glucose and discuss the beneficial and detrimental engineering steps in detail. Fatty acid secretion was achieved through the deletion of fatty acyl-CoA synthetases and overexpression of the truncated E. coli thioesterase ‘TesA. The best strains secreted >1 g/L free fatty acids into the culture medium. Additionally, the introduction of C16-specific ∆9-desaturases and fatty acid synthases, coupled with improved cultivation conditions, increased the palmitoleic acid content from 5.5% to 22%.
... The separation of the products obtained by fermentation is a complex step that most often determines their price. Due to the structure of the products or the particularities of the biochemical systems, achieving high purities is difficult, with the part of the separation stage in the total cost being between 20 and 60%, sometimes even 90% [60]. ...
Due to its potential use in the production of new functional resins, bio-plastics, food additives, agrochemicals, and pharmaceuticals, muconic acid (MA), a high value-added bio-product with reactive dicarboxylic groups and conjugated double bonds, has attracted growing interest. Adipic acid, terephthalic acid, and trimellitic acid are examples of bulk compounds that can be produced using MA that are of high commercial importance. The development of biotechnological approaches for MA production has advanced greatly recently. The current analysis offers a thorough and organized summary of recent developments and difficulties in the extraction of MA. A variety of extractants are presented, along with any limitations and potential solutions. Finally, the possibilities for this field in light of its state, difficulties, and tendencies are explored.
... Particularly, downstream fermentation processes are costly considering that fermentation products that get solubilized in water at low concentrations are difficult to recover. In fact, downstream processing costs are reported to comprise 20%-40% of the total production cost for bio-based bulk chemicals (Straathof 2011). The simplification of downstream processes must be realized for fermentation to compete against chemical synthesis approaches. ...
To realize biomass refinery without complex downstream processes, we extensively screened for microbial strains that efficiently produce extracellular oil from sugars. Rhodotorula paludigena (formerly Rhodosporidium paludigenum) BS15 was found to efficiently produce polyol esters of fatty acids (PEFAs), which mainly comprised of 3-acetoxypalmitic acid and partially acetylated mannitol/arabinitol. To evaluate the performance of this strain, fed-batch fermentation was demonstrated on a flask scale, and 110 g/L PEFA and 103 g/L dry cells were produced in 12 days. To the best of our knowledge, the strain BS15 exhibited the highest PEFA titer (g/L) ever to be reported so far. Because the PEFA precipitated at the bottom of the culture broth, it could be easily recovered by simply discarding the upper phase. Various carbon sources can be utilized for cell growth and/or PEFA production, which signifies the potential for converting diverse biomass sources. Two different types of next-generation sequencers, Illumina HiSeq and Oxford Nanopore PromethION, were used to analyze the whole-genome sequence of the strain BS15. The integrative data analysis generated a high-quality and reliable reference genome for PEFA-producing R. paludigena. The 22.5-M base genome sequence and the estimated genes were registered in Genbank (accession numbers BQKY01000001–BQKY01000019).
Key points
• R. paludigena BS15 was isolated after an extensive screening of extracellular oil producers from natural sources.
• Fed-batch fermentation of R. paludigena BS15 yielded 110 g/L of PEFA, which is the highest titer ever reported to date.
• Combined analysis using Illumina and Oxford Nanopore sequencers produced the near-complete genome sequence.
... Even though SMB operations are not so common as in the sugar processing industry, SMB units have been used for the separation of lactic acid from acetic acid and for the separation of citric acid from unconverted glucose streams. Both examples use the synthetic resin polyvinylpyridine as adsorbent [74][75][76][77]. ...
In industry, recovery and purification of the desired end product is a crucial step in the production of many chemicals, arguably as important as the synthesis itself. The cost of separation and purification often contributes a large part of the total production cost. Selection of the appropriate separation technique and optimization of the purification process are hence of critical importance. Adsorption has been used since history for the purification and separation of both gaseous and liquid streams. Sand filtration is known since ancient times and is one of the first examples of human water treatment. Even though the exact nature and mechanism of adsorption processes have long not been well understood, adsorption has been used for a huge variety of applications through all of human history. The separation of dyes, contaminant removal from water, decolorization of sugars, and recovery of fermented products are only a few examples. Nearly every modern‐day industrial chemical‐manufacturing process requires some form of separation in general and adsorption in specific. For instance, every catalytic reaction on a solid catalyst is characterized by an adsorption step, potentially rate determining.
In this article, the basic fundamentals of adsorption, the different adsorbent types and process modes, and a selection of the most relevant industrial adsorptive separations are discussed.
... Many different methodologies and reactor types have been proposed for converting syngas to valuable biochemicals [20], but, to the best of our knowledge, the purification of syngas fermentation products is not that well studied. Since the downstream processing costs for bulk fermentation products, such as bioethanol, can add up to 20-40% of total production cost [21], optimization of this step can significantly improve the economic viability of the biofuel production process. ...
... That is mainly due to its high solubility in water, low titers caused by acid inhibition, decomposition at elevated temperatures, and generation of by-products (Komesu et al., 2017). Research of novel high efficient separation strategies is essential not only to meet these technical challenges but also to recover lactic acid at relatively low costs, as downstream processing represents between 20% and 40% of the total lactic acid production cost (Straathof, 2011). ...
... 8 Even though DSP costs are typically around 30−40% of total production costs, a competitive recovery process is critical in making CA production economically viable. 9 The DSP's goals are to obtain high purity of the top product while maintaining a high degree of recovery; however, this process mainly suffered due to the involvement of multistage complex steps in the purification process. 10 There are many other technologies available to manufacture the CA in large quantities, such as precipitation, extraction, adsorption, and membrane separation methods. ...
... Even though the catalysis is the first part of the process being optimized [52,54], the downstreaming part has to be also considered since the process needs to be handled as a whole. To have a general overview, up to 40% of the total cost of fermentatively produced bulk chemicals comes from downstream processing (DSP) [55]. Integrating the DSP with the (bio)catalysis cannot be considered new for PI. ...
In the last ten years, the number of publications related to process intensification (PI) has been quadrupled. This increasing interest that created many innovations can be found not only in chemo-catalytic processes but has also reached the field of enzymatic processes. The recent scientific and technological advances in bioprocess intensification have been dedicated to improving the use of enzymes in selective oxidative reactions, obtaining more environmentally friendly and resource efficient applications. In this mini-review, we provide an overview of the different PI definitions, and recent studies focusing on intensification of oxidative biocatalytic reactions regarding (i) non-conventional media, (ii) process data and analytics, (iii) reactor engineering, and (iv) downstream processing. Remarking how the advances of other fields can be used for process intensification and for obtaining new goals (e.g., PI 4.0). Model-based simulations and new technologies in sensors can guarantee optimal and more automated processes with new reactor designs, together with the use of non-conventional media and enzyme immobilization, to intensify biocatalytic oxidation processes.
... In industrial environments, such as sugar mills where large amount of nonedible lignocellulosic biomass is generated every day, production of bioethanol using in-house-produced cellulases can generate surplus income with minimal investment in equipment costs and easy disposal of microbial waste. In such a process setting, the cost of carbohydrates will ultimately surpass the DSP costs, but cannot be clearly defined due to the generation of coproduct credits and energy requirements of the process through recycling or other side-stream processes in the highly integrated fermentation biorefinery [23]. Further modelling and analysis of cellulase production systems by Johnson has proven that integrated cellulase production systems lowers the ultimate cellulosic bioethanol cost when compared to that of off-site systems [24]. ...
The economic uncertainty associated with cellulosic bioethanol can be overcome through the inclusion of cheap substrates and methodologies that can extend the shelf life of cellulolytic enzymes. In this study, wild Trichoderma viride was used to produce cellulases, media formulation studies were conducted to enhance the cellulase production further and immobilization strategies were tested for stable cellulase–iron oxide magnetic nanoparticle coupling. Out of the seven different production media designed, media containing glucose, wheat bran, cellulose and corn steep liquor supported the highest biomass growth (60 Packed cell volume) and cellulase formation (7.4 U/mL), and thus was chosen for the fiscal analysis at a larger scale (1000 m3). The profitability of the cellulase production process was assessed to be 20.86%, considering both the capital expenditure and operating expenses. Further, the effect of cost of different carbon sources, nitrogen sources and cellulase yields on the annual operating costs was explored, which led to the choice of delignified sugarcane bagasse, corn steep liquor and productivity levels to be respective decisive factors of the overall cost of the cellulase production. Likewise, the break-even period of such a large-scale operation was gauged given the market price of cellulases at USD 17 for 105 U of cellulases. Moreover, enzyme immobilization led to enhanced cellulase shelf life and ultimately contributed toward saccharification cost reduction.
... A crucial step in CA production is represented by the downstream process, which has been estimated to account for 30-40% of the selling price [46]. It must be considered that the complexity of the procedure can be greatly influenced by the type of fermentation (SSF, SF or SmF) and by the fermentation substrate; for instance, the use of agro-food wastes may require additional steps to obtain a high-purity product. ...
The industrial relevance of organic acids is high; because of their chemical properties, they can be used as building blocks as well as single-molecule agents with a huge annual market. Organic acid chemical platforms can derive from fossil sources by petrochemical refining processes, but most of them also represent natural metabolites produced by many cells. They are the products, by-products or co-products of many primary metabolic processes of microbial cells. Thanks to the potential of microbial cell factories and to the development of industrial biotechnology, from the last decades of the previous century, the microbial-based production of these molecules has started to approach the market. This was possible because of a joint effort of microbial biotechnologists and biochemical and process engineers that boosted natural production up to the titer, yield and productivity needed to be industrially competitive. More recently, the possibility to utilize renewable residual biomasses as feedstock not only for biofuels, but also for organic acids production is further augmenting the sustainability of their production, in a logic of circular bioeconomy. In this review, we briefly present the latest updates regarding the production of some industrially relevant organic acids (citric fumaric, itaconic, lactic and succinic acid), discussing the challenges and possible future developments of successful production.
... For example, the Pörner Group offers this as a pre-planned industrial facility [13]. Although this process is already used in industrial scale, it can be enhanced in terms of efficiency, as acetaldehyde is an intermediate in bioethanol production, and 15% of the bioethanol production cost emerge in the downstream processing [14] A direct bioacetaldehyde production would circumvent the need for two purification steps. ...
Acetaldehyde is a platform chemical with a production volume of more than 1 Mt/a, but is chiefly synthesized from petrochemical feedstocks. We propose the fermentative conversion of glucose towards acetaldehyde via genetically modified S. cerevisiae . This allows for ethanol-free bioactaldehyde production. Exploiting the high volatility of the product, in situ gas stripping in an aerated reactor is inevitable and crucial due to the respiratory toxicity effects of the acetaldehyde overproduction. We devise a lab-scale setup for the recovery of the product from the off-gas. Water was chosen as a suitable solvent and the Henry coefficient of acetaldehyde in water was validated experimentally. Based on an experimentally verified capture efficiency of 75%, an acetaldehyde production rate of over 100 mg/g/h was reached in 200 mL lab-scale fermentations.
... Efforts in developing intensified downstream separation and purification steps in bioprocessing have been ongoing for a long time, with the need to develop integrated continuous upstream and downstream stages being recognised to be of utmost importance for the continuous operation philosophy to be put into practice in bioprocessing [99]. Large improvements in, for example, cell culture titers has resulted in further pressure and cost of the downstream processes [100] and future improvements in downstream processing is required to debottleneck it [101] as well as significantly reduce costs, which, for industrial scale manufacture of biopharmaceuticals, currently accounts for between 45-92% of the total cost [102]. Key steps can be divided in cell separation & products extraction, purification and formulation [103]. ...
With the current pressing need to rise to the ambition of net zero targets to mitigate carbon emissions and climate change impacts, sustainable processing has never been more critical. Bioprocessing has all the desirable attributes to respond to the sustainable processing challenge: use of cheap, renewable resources, nature-inspired, highly selective biocatalysts operating optimally under mild conditions and reduced energy consumption/carbon footprint. With bioprocessing productivity being far from ideal to meet the large-scale need for food, drugs, biofuels and bio-based chemicals, there has been tremendous interest of late in developing intensified bioprocesses, with significant advancement achieved in tailoring and utilising the technologies in the toolbox traditionally applied in chemical process intensification.
This review highlights the wide range of activities currently on-going in bioprocess intensification, focusing on upstream, bioreactor/fermentation and downstream separation steps. Great strides have been made in biocatalyst engineering and high density cell immobilisation for significant productivity enhancement, which, in conjunction with elegant process innovations such as novel bioreactor technologies and in-situ product separations, are enabling bioprocesses to become more competitive than ever before. The future prospects of bioprocess intensification are promising but there are still challenges that need to be overcome to fully exploit this technology.
... Cheese whey and vinification lees (Rodríguez-Pazo et al., 2016), fish wastes (Vázquez et al., 2019), brewer's spent grain (Paz et al., 2018) and soy whey (Mitra et al., 2010) are some examples of industrial residues used as substrates for bacteriocin production by LAB. Considering that the carbohydrate source accounts for 15 to 60% of production costs (Straathof, 2011), the use of carbohydrates from lignocellulosic biomass as renewable raw material has been proposed for alternative large-scale biotechnological production processes (Du et al., 2012). An option is sugarcane bagasse, the main lignocellulosic biomass generated by the sugarcane industry, which has been explored for the production of a broad group of biotech products due to its high abundance, low cost, renewability and high fermentable carbohydrate content. ...
Listeria monocytogenes is one of the foodborne pathogens of most concern for food safety. To limit its presence in foods, bacteriocins have been proposed as natural bio-preservatives. Herein, a bacteriocin was produced on hemicellulose hydrolysate of sugarcane bagasse by Pediococcus pentosaceous ET34, whose genome sequencing revealed an operon with 100% similarity to that of pediocin PA-1. ET34 grown on hydrolysate-containing medium led to an increase in the expression of PA-1 genes and a non-optimized purification step sequence resulted in a yield of 0.8 mg·L-1 of pure pediocin (purity > 95%). Culture conditions were optimized according to a central composite design using temperature and hydrolysate % as independent variables and validated in 3-L Erlenmeyers. Finally, a process for scaled-up implementation by sugar-ethanol industry was proposed, considering green chemistry and biorefinery concepts. This work stands up as an approach addressing a future proper sugarcane bagasse valorisation for pediocin production.
... Prior to any RES production at a larger scale using the developed biphasic extraction process, the extraction efficiency would have to be increased to ensure economic viability of the overall process. 54,55 A higher pH during back extraction would increase the yield, but pH-dependent RES recovery at a very high pH values is unfeasible due to RES instability. 56 Nevertheless, during our experiments, no product loss was observable after 3 h of incubation at an alkaline pH of 12 at room temperature and subsequent cooling of the aqueous phase. ...
Microbial synthesis of aromatic compounds is generally limited by inherent product toxicity toward the producing cells. Here, in situ extractive strategies represent an efficient approach to avoid such toxic effects and to increase the overall process performance. We conducted a solvent screening to identify suitable organic solvents to develop a biphasic extractive strategy for microbial plant polyphenol production using Corynebacterium glutamicum. From 10 pre-selected organic solvents, tributyrin (TB) showed the best biocompatibility and was chosen for the biphasic extraction process due to its beneficial effect on partitioning and solubility of the plant polyphenol resveratrol. In bioreactors, biphasic cultivation with TB allowed for a product titer of 7.5 mM (1.71 g L–1) resveratrol with a volumetric productivity of 0.26 mM h–1 and a product yield of 0.92 mol mol–1. This biphasic cultivation procedure can be directly employed for the synthesis of other aromatics with similar properties using C. glutamicum.
... An example of this USP intensification is the overall mammalian cell culture production capacity increased from 700,000 L to 2,550,000 L in 2010 probably requires additional chromatographic columns or investment on chromatography techniques, as well as any costs related to subsequent filtration steps requiring larger areas or filtration times (Farid 2009;Yang, Qadan, and Ierapetritou 2019;Gronemeyer, Ditz, and Strube 2014;Sommerfeld and Strube 2005). In some cases, DSP mAb production can make of 50% to 70% of all the total COGs of production (Straathof 2011). However, the COGs/g can still fall if the increase in overall productivity outweighs this cost increases. ...
This thesis aims to understand current counter-current tangential chromatography (CCTC) design in bioprocessing. It assesses the structural and performance changes that occur in agarose- and synthetic-based chromatography resins as they are exposed to different equipment designs in order to improve resin lifetime and operational simplicity. The mixing and tangential flow filtration modules were characterized to provide a minimum residence time of 120 seconds and an operational flux of 70 LMH. The chromatography resin was used in different equipment designs for 36 hours to assess the performance and structural properties. The results indicate that the shear caused by peristaltic pumps and hollow fibres caused an average size reduction of 5% in both synthetic and agarose resins. However, the agarose-based resin had significantly deformed. Both resins exhibited a deviation of 5% from their original dynamic binding capacity. The system’s separation performance was tested using a two-component separation (BSA and myoglobin) and a salt step gradient separation of ovalbumin variants. The two-component separation was a success with a purity and a yield of 99.9% and 93.2%, respectively. In contrast when attempting the more challenging separation of closely related ovalbumin variants using a step-gradient separation the inline mixing in the CCTC system prevented successfully separation. Different coiled flow inverter reactor (CFIR) designs were explored as viable mixing modules for their operational flexibility, system simplification and cost-effectiveness. The best performing CFIR (λ 13.8) showed inferior results to the set of static mixers showing a normalised batch binding capacity of 0.9 and 1.0, respectively. However, this CFIR showed to be a more cost-effective reactor by being 17x cheaper while operating at 90% binding capacity efficiency. The project established critical considerations for adsorbent use and CFIRs as a simplified and cost-effective mixing option, which aids the adoption of this technology for biopharmaceutical manufacturing.
... Acid tolerance of microorganisms and metabolic engineering strategies for improving it will be discussed in Section 3. Final product recovery and purification is another critical step for the commercialization of bio-based compounds. For organic acids, these downstream operations may account for 20 to 60% of the entire production process cost [19,74]. Downstream processing of fermentative carboxylic acids generally combines multiple methodologies for removing major impurities (e.g., adsorption, extraction, precipitation, electrodialysis), water, and minor contaminants (e.g., reverse osmosis, evaporation, distillation, chromatography) [75]. ...
Several organic acids have been indicated among the top value chemicals from biomass. Lignocellulose is among the most attractive feedstocks for biorefining processes owing to its high abundance and low cost. However, its highly complex nature and recalcitrance to biodegradation hinder development of cost-competitive fermentation processes. Here, current progress in development of single-pot fermentation (i.e., consolidated bioprocessing, CBP) of lignocellulosic biomass to high value organic acids will be examined, based on the potential of this approach to dramatically reduce process costs. Different strategies for CBP development will be considered such as: (i) design of microbial consortia consisting of (hemi)cellulolytic and valuable-compound producing strains; (ii) engineering of microorganisms that combine biomass-degrading and high-value compound-producing properties in a single strain. The present review will mainly focus on production of organic acids with application as building block chemicals (e.g., adipic, cis,cis-muconic, fumaric, itaconic, lactic, malic, and succinic acid) since polymer synthesis constitutes the largest sector in the chemical industry. Current research advances will be illustrated together with challenges and perspectives for future investigations. In addition, attention will be dedicated to development of acid tolerant microorganisms, an essential feature for improving titer and productivity of fermentative production of acids.
Increasing attention has been paid to the purity of therapeutic proteins imposing extensive costs and challenges to the downstream processing of biopharmaceuticals. One of the efforts, that has been exerted to overcome such limitations, was developing multimodal or mixed‐mode chromatography (MMC) resins for launching selective, orthogonal, non‐affinity purification platforms. Despite relatively extensive usage of MMC resins, their real potential and fulfillment have not been extensively reviewed yet. In this work, the explanation of practical and key aspects of downstream processing of recombinant proteins with or without MMC resins was debated, as being useful for further purification process development. This review has been written as a step‐by‐step guide to deconvolute both inherent protein purification and MMC complexities. Here, after complete elucidation of the potential of MMC resins, the effects of frequently used additives (mobile phase modifiers) and their possible interactions during the purification process, the critical characteristics of common product‐related impurities (e.g., aggregates, charge variants, fragments), host‐related impurities (e.g., host cell protein and DNA) and process related impurities (e.g., endotoxin, and viruses) with solved or unsolved challenges of traditional and MMC resins have been discussed. Such collective experiences which are reported in this study could be considered as an applied guide for developing successful downstream processing in challenging conditions by providing a clear insight into complex MMC resins and impurities.
Mannosylerythritol lipid (MEL) is a microbial surface‐active glycolipid biosurfactant produced by numerous microorganisms. MEL is produced as a major product by Pseudozyma sp. and as a minor product by Ustilago sp. MEL has recently received much practical attention due to its structural diversity, broad biochemical functions, and biocompatibility with the environment. In this review, the production of MEL from various feedstocks, and antimicrobial and antiadhesive properties are discussed. Furthermore, the applications of MEL as an antimicrobial agent in food, moisturizer in cosmetics, as an apoptotic agent in pharmaceuticals, and as a wetting agent in agriculture applications are highlighted. Finally, an overview of MEL production from waste materials presents huge potential for increasing the necessary change to a circular economy.
Bio‐based production of fuels, chemicals and materials is needed to replace current fossil fuel based production. However, bio‐based production processes are very costly, so the process needs to be as efficient as possible. Developments in synthetic biology tools has made it possible to dynamically modulate cellular metabolism during a fermentation. This can be used towards two‐stage fermentations, where the process is separated into a growth and a production phase, leading to more efficient feedstock utilization and thus potentially lower costs. This article reviews the current status and some recent results in application of synthetic biology tools towards two‐stage fermentations, and compares this approach to pre‐existing ones, such as nutrient limitation and addition of toxins/inhibitors.
Protein purifications based on phase separations (e.g., precipitation and liquid‐liquid extraction) have seen little adoption in commercial protein drug production. To identify barriers, we analyzed the purification performance and economics of 290 phase separation purifications from 168 publications. First, we found that studies using Design of Experiments for optimization achieved significantly greater mean yield and host cell protein log 10 removal values than those optimizing one factor at a time (11.5% and 53% increases, respectively). Second, by modeling each reported purification at scales from 10 to 10,000 kg product/year and comparing its cost‐effectiveness versus chromatography, we found that cost‐effectiveness depends strongly on scale: the fraction of phase separations predicted to be cost‐effective at the 10, 100, and 1000 kg/year scales was 8%, 15%, and 43%, respectively. Total cost per unit product depends inversely on input purity, with phase separation being cheaper than chromatography at the 100 kg/year scale in 100% of cases where input purity was ≤ 1%, compared to about 25% of cases in the dataset as a whole. Finally, we identified a simple factor that strongly predicts phase separation process costs: the mass ratio of reagents versus purified product (the “direct materials usage rate”), which explains up to 58% of variation in cost per unit of purified product among all 290 reports, and up to 98% of variation within particular types of phase separation.
Background: Protein downstream processing remains a challenge in protein production, especially in low yields of products, in spite of ensuring effective disruption of cell and separation of target proteins. It is complicated, expensive and time-consuming. Here, we report a novel nano-bio-purification system for producing recombinant proteins of interest with automatic purification from engineered bacteria.
Results: This system employed a complete genetic engineering downstream processing platform for proteins at low expression levels, referred to as a genetically encoded magnetic platform (GEMP). GEMP consists of four elements as follows. (1) A truncated phage lambda lysis cassette (RRz/Rz1) is controllable for lysis of Magnetospirillum gryphiswaldense MSR-1 (host cell). (2) A surface-expressed nuclease (NucA) is to reduce viscosity of homogenate by hydrolyzing long chain nucleic acids. (3) A bacteriogenic magnetic nanoparticle, known as magnetosome, allows an easy separation system in a magnetic field. (4) An intein realizes abscission of products (nanobodies against tetrabromobisphenol A) from magnetosome.
Conclusions: In this work, removal of most impurities greatly simplified the subsequent purification procedure. The system also facilitated the bioproduction of nanomaterials. The developed platform can substantially simplify industrial protein production and reduce its cost.
The recovery of a product obtained by a biotechnological process can represent from 30 to 90% of the total cost of the process, depending, among other factors, on the type of product and the degree of purity necessary to make its use viable. The recovery of xylitol obtained by bioprocess is not yet technologically established, both because of the complexity of the raw materials used in the process and the purity required, as it is a food grade product. There is a range of key operations for the recovery of a bioproduct and, for xylitol, crystallization seems to be of great importance today and, apparently, the most promising. In this chapter, initially an introduction to the recovery and purification of bioproducts in general is presented, aiming to allow a connection with the strategies that will be presented for the case of xylitol. Then, the most relevant works found in the literature so far are discussed, showing the updated panorama. Emphasis was given to crystallization as a key operation for obtaining xylitol in commercial form. Finally, some future perspectives regarding the recovery and purification of xylitol obtained by biotechnological process were discussed.KeywordsXylitolDownstreamRaw materialsLignocellulosicsCrystalizationBioproducts
Nowadays, many fermentation chemicals are produced at an industrial scale. Numerous technological improvements have been developed and implemented to achieve high quality and quantity of fermentation products. However, several drawbacks in fermentation processes still limit their application at an industrial level. In situ product removal (ISPR) is a potential alternative to overcome the conventional drawbacks of the fermentative processes, increasing the fermentation's productivity and reducing the separation steps for recovery and purification. Currently, liquid extraction has emerged as a promising separation technology for ISPR, with immobilized liquids such as membrane-assisted extraction and microchannel liquid membrane, due to the high mass transfer rates, scalability, easy integration, and efficiency. This chapter will discuss these technologies regarding their integration into fermentative processes.
Carbon monoxide (CO) is a key material in C1chemistry for chemical production and CO2reduction, whereas in applications, such as H2for fuel cells, its concentration must be kept below 0.2 ppm. Adsorption technology is useful for both CO removal and production to provide environmental sustainability for the energy and chemical industries. In this review, the CO adsorption performances of various adsorbents, such as activated carbons, zeolites, metal-organic frameworks, activated alumina, mesoporous silicas, and their modified adsorbents, are collected, and their physical and chemical properties and CO selectivities are summarized. Cu⁺impregnation is a powerful and widely used modification method to enhance the CO adsorption of adsorbents. Therefore, the preparation methods and their effects on CO adsorption are also compared and reviewed. The data and analysis in this review can provide insights for the development of novel adsorbents and processes for CO removal and production.
The application of reverse osmosis (RO) and nanofiltration (NF) to concentrate and/or fractionate volatile fatty acids (VFAs, occurring in acidogenic effluents) was systematically assessed for the first time using three commercial spiral wound modules. A bench scale plant was used to test the polyamide membrane cartridges, namely: AG1812-34D, DK1812-34D and NFS-3B-1812F. The effects of main operational parameters (pH, temperature, applied pressure) were firstly studied in total recirculation mode, using different total and relative VFA compositions. Thereafter, batch concentration tests were carried out (at constant applied pressure, ca. 30 bar) to fully characterize the RO and NF modules. AG1812-34D performed as an RO module and it allowed concentrating target solutions almost 3 times without relevant VFA losses (<4%) in the permeate side. All tested parameters were observed to affect concentration performances. However, typical pH levels occurring in acidogenic effluents allowed to achieve fully satisfactory VFA rejections. DK1812-34D and NFS-3B-1812F performed as NF modules and could represent suitable solutions for VFA fractionation. Separation factors significantly increased by pH rise; in particular, high acetic and propionic acid separation factors over butyric acid were achieved at pH 9, with DK1812-34D module.
Countercurrent membrane supported reactive extraction (MSRE) was studied for removal of carboxylic acids from aqueous streams with a PTFE capillary membrane. Analysis of the mass transfer rates was performed to support modeling of the process. Total mass transfer coefficients ranging from 2.0·10⁻⁷ to 4.0·10⁻⁷ m/s were obtained when extracting lactic acid with 20 wt% tri-N-octyl amine in 1-decanol with membrane thicknesses of 260 µm and 80 µm. The limiting mass transfer resistance in all experiments was in the membrane phase. The developed model based on mass transfer and reaction in parallel allows to predict countercurrent extraction. Experimental validation with 5, 7 and 12 m long membrane modules showed excellent accordance for two acids, validating the model simulations. Simulated membrane contactor lengths required for single, two and three countercurrent stages varied between 10 and 39 m/stage for lactic, mandelic, succinic, itaconic and citric acid, depending on acid, membrane, and diluent.
Parameter estimation for scale‐up of downstream operations from microtiter plates (MTPs) is mostly done empirically because engineering correlations between microplates and stirred tank reactors (STRs) are not yet available. It is challenging to change the operation mode from shaken MTPs to large‐scale STRs. For the scale‐up of STRs, volumetric power input is well‐established although it is unclear whether this parameter can be used to transfer the operations from MTPs. We determine the volumetric power input in MTPs via the temperature increase caused by the motion of the liquid. The hydrodynamics in MTPs are studied with computational fluid dynamics (CFD). Mixing is investigated in 96‐, 24‐, and 6‐well MTPs to cover different geometries, filling volumes, shaking diameters, and shaking frequencies. All CFD simulations are validated by experimental results, which now allows prediction of the volumetric power input and hydrodynamics at various conditions in MTPs without the need for further experiments. We provide a map of the power input achievable in MTPs. Based on this map, from knowing about large‐scale conditions, adequate microscale conditions can be adjusted for process development. This enables the direct scale‐up of downstream unit operations from MTPs to STRs.
This article details an economic assessment of butanol production from corn using the newly developed hyper-butanol-producing strain of Clostridium beijerinckii BA101. Butanol is produced in batch reactors and recovered by distillation. For a plant with 153,000 metric tons of acetone, butanol, and ethanol (ABE) production capacity, the production equipment cost and total working capital cost is US110.46x10(6), respectively. Based on a corn price (C(p)) of US2.01 x bushel(-1)), an ABE yield of 0.42 (g ABE/g glucose) butanol price is projected to be US0.29 x kg(-1). Assumptions, such as by-product credit for gases and complete conversion of corn steep liquor (CSL) to fermentation by-products, have been taken into consideration. An increased price of corn to US0.47 x kg(-1). A grass-rooted plant would result in a butanol price of US79.23 x ton(-1)). In a worst case scenario, the price of butanol would increase to US197.10 x ton(-1).
Coulson and Richardson's Chemical Engineering: Volume 3B: Process Control, Fourth Edition, covers reactor design, flow modeling, and gas-liquid and gas-solid reactions and reactors.
The effects of fermentation performance on the final production cost of poly(3-hydroxybutyrate) [P(3HB)] were examined. Two processes for the production of P(3HB) byAlcaligenes latus from sucrose with the recovery method of surfactant-hypochlorite digestion were designed and subsequently analysed. The actual fermentation results that were different in the final P(3HB) content, P(3HB) yield and P(3HB) productivity were used in the simulations. The production cost of P(3HB) was significantly lower with higher P(3HB) content due to the reduction in polymer recovery cost. The cost of raw materials (mainly sucrose) was also lower with higher P(3HB) content since the process yielding higher P(3HB) content also resulted in higher P(3HB) yield on carbon source. The direct fixed capital-dependent costs decreased with increasing productivity. By employing the fermentation process that resulted in high P(3HB) concentration, P(3HB) content and P(3HB) productivity of 98.7 g/l, 88.3% and 4.94 g P(3HB)/l/h, respectively, the final production cost of P(3HB) was as low as US $2.6/kg P(3HB).
IntroductionChallenges When Striving for the Cost-Effective Manufacture of mAbsCost Definitions and Benchmark ValuesEconomies of ScaleOverall Process Economic DriversDSP Drivers at High TitersProcess Economic Trade-Offs for DSP BottlenecksSummary and OutlookReferences
This paper summarizes the main findings of a round-table discussion held to examine the key bottlenecks in the further application and industrial implementation of in-situ product removal (ISPR) techniques.** It is well established that ISPR can yield great benefits for processes limited by inhibitory or toxic products, as well as unstable products or reactions that are thermodynamically unfavorable. However, several issues for industrial implementation were revealed in the discussion. Most notably implementation will be dependent on (1) research into the appropriate process structure, (2) methods to achieve process robustness, (3) systematic selection methods for separation operations and (4) the nature of the product market. Here, these four issues will be discussed as a basis for future work in this area. Copyright © 2007 Society of Chemical Industry
Several processes for the production and recovery of poly(3-hydroxybutyrate) (PHB) by Alcaligenes eutrophus, Alcaligenes latus, Methylobacterium organophilum, and recombinant Escherichia coli were designed based on the previously reported data and analyzed by computer-aided bioprocess design. PHB productivity, content, and yield significantly affected the final price of PHB. For the annual production of 2,850 tonnes of purified PHB, the process employing A. eutrophus with the recovery method of surfactant-hypochlorite digestion resulted in lowest price of PHB, 5.58/kg. As the production scale increased to one million tonnes per year, the price of PHB dropped to 5.58/kg. As the production scale increased to one million tonnes per year, the price of PHB dropped to 4.75/kg. The cost of carbon substrate significantly affected the overall economics in large production scale. Therefore, the production cost can be considerably lowered when agricultural wastes, such as whey and molasses, are used.
The widely anticipated economic potential of fed-batch operation was quantified for a therapeutic product by flowsheet simulation. A process for production of t-PA from CHO cells based on fed-batch operation was compared to a base process that operates in batch mode. Two cases of fed-batch operation were considered, case A, where the product concentration was assumed to be four times the concentration obtained with base process and case B, where the concentration was eight times. The simulator, Bioprocess Simulator (BPS) from Aspen Technology, reported the final bioreactor volume and the total amount of the continuous feeds added during the fed-batch operation. BPS was also used to simulate the downstream processes. Comparison of the economic performances of the processes revealed that return on investment (ROI) of the base process would increase by 112% by switching to case A fed-batch operation from batch mode. Case B, on the other hand, would result in an increase of 288%. The importance of downstream processing for recovery of high-value products became apparent from this study. A breakdown of equipment purchase cost showed that the contribution from the product recovery section increased from 62% for base case to 77% for case A as the product concentration increased by fed-batch operation. For a fixed recovery of 40%, contribution from the downstream section was found to decrease to 70% for case B compared to case A. It was concluded from the results that higher product concentration would not result in proportionate increase in ROI because of limitations in the recovery section. A sensitivity analysis was carried out on several uncertainties of the simulated fed-batch process.
The preliminary design and costing of a 100 million litres/year wheat-ethanol plant using continuous cell recycle fermentation, where the cells were separated after the fermentation using cross-flow membrane filters, were investigated. As part of the design, two other unconventional steps were required: the separation of suspended solids before saccharification and the hydrolysis of dextrins by immobilized enzymes. The total capital cost was estimated as Can1.15 = Can90/tonne, a total operating expenditure of Can460 per 1000 litres of ethanol, the total income (including by-products) was estimated at Can7 million/year. It should be noted, however, that the wheat cost makes up over 60% of the total operating expenditure and as such the profit would drop rapidly with increases in this cost.
A process for the fermentative production of lactic acid from whole-wheat flour consisting of starch and bran containing nutrients is presented and an economical evaluation of the lactic acid production cost performed. Bottlenecks were identified and alternative processes were evaluated and compared. The costs of raw material, the sodium hydroxide in the fermentation step, and the conversion of lactate to lactic acid using electrodialysis were found to contribute considerably to the total production cost. Performing the fermentation step as a batchwise step was economically better than continuous fermentation. The lactic acid production cost can be reduced by lowering the pH and/or by recycling the sodium hydroxide produced by electrodialysis to the fermentor. Using higher wheat flour concentrations reduced the lactic acid production cost and numerical optimisation of the process, with respect to the wheat flour concentration, showed that the optimal concentration corresponded to 116 g glucose/l, which resulted in a production cost of 0.833 US/kg was 61% or 91%, respectively.
In the present work an economic analysis of the production of Penicillium restrictum lipase in both submerged (SF) and solid state fermentations (SSF) was performed. For a production scale of 100 m3 lipase concentrate per year, total capital investment needed for the submerged process was 78% higher than that needed for the solid-state fermentation process. The submerged process proved to be economically unfeasible, as unitary product cost was 68% higher than the product selling price. Contrastingly, the solid-state fermentation process turned out to be very attractive from an economic point of view. Also for a scale of 100 m3/year, SSF unitary product cost was 47% lower than the selling price, payback time was 1.5 years, return on investment was 68% and internal return rate was 62% for a 5-year-project life. Furthermore, the profitability of this process remained high even with eventual increases of 40% in product concentration or total capital investment, or decreases of 20% in product price. The great advantage of the SSF process is the extremely cheap raw material it uses as main substrate.
The corn dry-grind process is the most widely used method in the U.S. for generating fuel ethanol by fermentation of grain. Increasing demand for domestically produced fuel and changes in the regulations on fuel oxygenates have led to increased production of ethanol mainly by the dry-grind process. Fuel ethanol plants are being commissioned and constructed at an unprecedented rate based on this demand, though a need for a more efficient and cost-effective plant still exists.A process and cost model for a conventional corn dry-grind processing facility producing 119 million kg/year (40 million gal/year) of ethanol was developed as a research tool for use in evaluating new processing technologies and products from starch-based commodities. The models were developed using SuperPro Designer® software and they handle the composition of raw materials and products, sizing of unit operations, utility consumptions, estimation of capital and operating costs, and the revenues from products and coproducts. The model is based on data gathered from ethanol producers, technology suppliers, equipment manufacturers, and engineers working in the industry. Intended applications of this model include: evaluating existing and new grain conversion technologies, determining the impact of alternate feedstocks, and sensitivity analysis of key economic factors. In one sensitivity analysis, the cost of producing ethanol increased from US 0.365 l−1 (US 1.38 gal−1) as the price of corn increased from US 0.125 kg−1 (US 3.20 bu−1). Another example gave a reduction from 151 to 140 million l/year as the amount of starch in the feed was lowered from 59.5% to 55% (w/w).This model is available on request from the authors for non-commercial research and educational uses to show the impact on ethanol production costs of changes in the process and coproducts of the ethanol from starch process.
In manufacturing of biological drugs, product quality is defined by the process (e.g. equipment, sequence of unit operations, operation parameters) because no complete analysis of these complex molecules is possible. Therefore, the process is unavoidably fixed after the first clinical lot production in a pilot plant. There is no further process optimization option parallel to production, which, in the case of small molecule productions, allows further process optimization.Process development times will not increase in future due to increasing pressure on time to market. In addition to that, no change in paradigm seems possible, as complete analysis of complex biomolecules comparable to small synthetic drugs is not seen in near future.As a consequences the challenge is to establish generic processes for different drug classes and to find consistent process development methods, which allow a reliable prediction of large-scale production.Generic in this sense is not understood as a fixed sequence of unit operations with a certain set of generic process parameters. Here, generic means that a typical arrangement of unit operations is set up in an efficient sequence to fulfil the separation task.
The economics of fuel ethanol production from dry-milled corn starch were studied in fluidized-bed bioreactors (FBRs) using immobilized biocatalysts. Glucoamylase immobilized on porous diatomaceous earth was used for hydrolysis of the starch to glucose in a packed-bed reactor. The fermentation of glucose to ethanol was carried out in FBRs using Zymomonas mobilis immobilized in κ-carageenan beads. Volumetric ethanol productivities of up to 24 g/l h were achieved in non-optimized laboratory-scale systems. For a 15 million gal/yr ethanol plant, an economic analysis of this process was performed with Aspen Plus (Aspen Technology, Cambridge, MA) process simulation software. The analysis shows that an operating cost savings in the range of 1.1–3.1 cents/gal can be realized by using the FBR technology.
Heparinase I from flavobacterium heparinum has several potential clinical applications; the resulting high demands on protein purity and quantity can be met by recombinant expression in Escherichia coli. Based on laboratory scale experiments with insoluble heparinase I expression followed by renaturation, a process for production of 3 kg/year of heparinase I was designed. We present a comparative analysis of the production costs of soluble and insoluble heparinase I expression, as well as a generalized approach to sensitivity analysis, based on perturbation around a base case design scenario. This may assist focusing further development on process steps for which improvements both are feasible and result in significant cost saving.
An efficiency and economic analysis of the bioseparation of different bioproducts is presented by utilizing different case studies. Economic data on bioseparation processes is rarely presented in the open literature. The different examples presented together attempt to provide an overall framework for the cost structure involved in the different bioseparation processes. The models presented (Datar, 1986; Porter and Ladisch, 1992) provide novel insights into the cost structure of the different aspects of bioseparation processes. More studies are required that provide the insights necessary to assist in improving the efficiency and economics of bioseparation processes.
A production process for B. thuringiensis (Bt) bioinsecticides was designed in detail, including alternative batch, low-density fed-batch (LDFB), and high-density fed-batch (HDFB) fermentation configurations. Capital and operating costs, as well as profitability based on simple rate of return, were performed using a purpose-written FORTRAN program, explicitly analyzing production of a water-based flowable product used in forestry applications.
The total capital cost was 1.5 million yearly, of which approximately half was for formulation ingredients. Per-unit production cost rose sharply for scales of less than 1 × 107 BIU/year, but was little affected by scale above 3 × 107 BIU/year. Product cost was much lower at all scales for a LDFB as opposed to batch fermentation process, but HDFB gave relatively little additional cost benefit. Profitability analysis performed by co-varying scale and selling price showed that break-even occurred at a price of 0.35/BIU gave a 12% rate of return. Since the assumed base scale would represent 8-15% of current world Bt bioinsecticide production, based on value or volume, it was concluded that profitability would require some or all of the following elements: targeting higher-value markets such as disease vector control, in addition to forestry; a potentially lower plant capacity (although at least 1 × 107 BIU/year;) and coproduction of other large-volume microbial products to absorb capacity and match bioinsecticide output to market demand.
Pressures for cost-effective manufacture of antibodies are growing given their high doses and increasing market potential that have resulted in significant increases in total site capacities of up to 200,000 L. This paper focuses on the process economic issues associated with manufacturing antibodies and reviews the cost studies published in the literature; many of the issues highlighted are not only specific to antibodies but also apply to recombinant proteins. Data collated at UCL suggest current benchmark investment costs of 1580/ft2 (17,000/m2) and 4220/L for antibody manufacturing facilities with total site capacities in the range of 20,000-200,000 L; the limitations of the data are highlighted. The complications with deriving benchmark cost of goods per gram (COG/g) values are discussed, stressing the importance of stating the annual production rate and either titre or fermentation capacity with the cost so as to allow comparisons. The uses and limitations of the methods for cost analysis and the available software tools for process economics are presented. Specific examples found in the literature of process economic studies related to antibody manufacture for different expression systems are reviewed. The key economic drivers are identified; factors such as fermentation titre and overall yield are critical determinants of economic success. Future trends in antibody manufacture that are driven by economic pressures are discussed, such as the use of alternative expression systems (e.g. transgenics, E. coli and yeast), disposables, and improvements to downstream technology. The hidden costs and the challenges in each case are highlighted.
This work presents a review of studies on the process economics of ethanol production from lignocellulosic materials published since 1996. Our objective was to identify the most costly process steps and the impact of various parameters on the final production cost, e.g. plant capacity, raw material cost, and overall product yield, as well as process configuration. The variation in estimated ethanol production cost is considerable, ranging from about 0.13 to 0.81 US per metric ton in the papers studied, and the plant capacity, which influences the capital cost. To reduce the ethanol production cost it is necessary to reach high ethanol yields, as well as a high ethanol concentration during fermentation, to be able to decrease the energy required for distillation and other downstream process steps. Improved pretreatment methods, enhanced enzymatic hydrolysis with cheaper and more effective enzymes, as well as improved fermentation systems present major research challenges if we are to make lignocellulose-based ethanol production competitive with sugar- and starch-based ethanol. Process integration, either internally or externally with other types of plants, e.g. heat and power plants, also offers a way of reducing the final ethanol production cost.
A novel design of a wheat-based biorefinery for bioethanol production, including wheat milling, gluten extraction as byproduct, fungal submerged fermentation for enzyme production, starch hydrolysis, fungal biomass autolysis for nutrient regeneration, yeast fermentation with recycling integrated with a pervaporation membrane for ethanol concentration, and fuel-grade ethanol purification by pressure swing distillation (PSD), was optimized in continuous mode using the equation-based software General Algebraic Modelling System (GAMS). The novel wheat biorefining strategy could result in a production cost within the range of dollars 0.96-0.50 gal(-1) ethanol (dollars 0.25-0.13 L(-1) ethanol) when the production capacity of the plant is within the range of 10-33.5 million gal y(-1) (37.85-126.8 million L y(-1)). The production of value-added byproducts (e.g., bran-rich pearlings, gluten, pure yeast cells) was identified as a crucial factor for improving the economics of fuel ethanol production from wheat. Integration of yeast fermentation with pervaporation membrane could result in the concentration of ethanol in the fermentation outlet stream (up to 40 mol %). The application of a PSD system that consisted of a low-pressure and a high-pressure column and employing heat integration between the high- and low-pressure columns resulted in reduced operating cost (up to 44%) for fuel-grade ethanol production.
Biochemical Engineering
- Blanch Hw
- D S Clark
Blanch HW and Clark DS (1996) Biochemical Engineering. New York, NY: Dekker.
DOI: 10.1016/B978-0-08-088504-9.00492-X Author's personal copy Downstream Processing and Product Recovery
Comprehensive Biotechnology, Second Edition, 2011, Vol. 2, 811-814, DOI: 10.1016/B978-0-08-088504-9.00492-X
Author's personal copy
Downstream Processing and Product Recovery
Coulson & Richardson's Chemical Engineering
- R K Sinrott
Sinrott RK (1999) Coulson & Richardson's Chemical Engineering, 3rd edn., vol. 6. Oxford: Butterworth-Heinemann.