An introduction to biotechnological innovations in the chemical industry 1.1 Introduction 1.2 Production processes
1 An introduction to biotechnological innovations in the chemical industry ~ 1.1 Introduction 1.2 Production processes 1.3 Choice of production pnxess
Chapter 1 An introduction to biotechnological innovations in the chemical industry 1.1 Introduction Although chemistry as an emperical fundamental dicipline has a long history, its application in industry gained importance after the introduction of the use of fossil nergy sources during the industrial revolution. The chemical industry withdraws non-renewable materials, mainly fossil oil, from the earth's reserves to use as an energy source and as ssi oil a source of raw materials for production processes. The products so produced are rather different from naturally occurring materials and mankind has become heavily dependent on them. However, other energy and raw material sources have to be sought because fossil sources are non-renewable and will eventually become depleated renewable Nowadays, renewable biological materials such as starch, sugar, oils and molasses are biological used on a relatively small scale as energy and raw materials for the chemical industry maunal These biological sources are mainly derived from waste products and overproduction in agriculture. With these materials less drastic conversions are applied, in comparison ith fossil oil, in order to make as much as possible of the chemical structure present in e raw material. Such conversions are therefore generally performed by micro-organisms or parts of them. This means that the production process includes at least one biological conversion step 1.2 Production processes Inproduction processes, raw material are converted into desired produc 8 unit operatons of unit operations. Such unit operations may be few in number and they are gether in a logical Typical unit t operations include such activities transport of solids and liquids, the transfer of heat, crysallisation, collection and drying In a chemical production process at least one of the unit operations(the chemical reactor)is the place in which chemical conversion takes place. Ho owever, the upstream& reactor is proceeded by a series of unit operations in which the new materials are instream prepared (the upstream operations). After conversion has taken place, the products are operations subjected to a further series of unit operations(the downstream operations).These downstream ope tions include product recovery and purification steps. a typical example of a production process is illustrated in Figure 1.1 Which of the unit operations described in Figure 1.1 represents the chemical reactor You should have identified the"conversion step
2 Chapter 1 non-renewable fossil oil renewable biibgical material mitoperations upstream& downstream operations An introduction to biotechnological innovations in the chemical industry 1.1 Introduction Although chemistry as an emperical fundamental dicipline has a long history, its application in industry gained importance after the introduction of the use of fossil energy sources during the industrial revolution. The chemical industry withdraws materials, mainly fossil oil, from the earth's reserves to use as an energy source and as a source of raw materials for production processes. The products so produced are rather different from naturally occurring materials and mankind has become heavily dependent on them. However, other energy and raw material sources have to be sought because fossil sources are non-renewable and will eventually become depleated. Nowadays, renewable biological materials such as starch, sugar, oils and molasses are used on a relatively small scale as energy and raw materials for the chemical industry. These biological sources are mainly derived from waste products and overproduction in agriculture. With these materials less drastic conversions are applied, in comparison with fossil oil, in order to make as much as possible of the chemical structure present in the raw material. Such conversions are therefore generally performed by micruorganisms or parts of them. This means that the production process includes at least one biological conversion step. 1.2 Production processes In production processes, raw material are converted into desired products using a series of unit operations. Such unit operations may be few in number and they are linked together in a logical sequence. Typical unit operations include such activities as the transport of solids and liquids, the transfer of heat, crysallisation, collection and drymg. In a chemical production process at least one of the unit operations (the chemical reactor) is the place in which chemical conversion takes place. However, the chemical reactor is proceeded by a series of unit operations in which the new materials are prepared (the upstream operations). After conversion has taken place, the products subjected to a further series of unit operations (the downstream operations). These downstream operations include product recovery and purification steps. A typical example of a production process is illustrated in Figure 1.1. Which of the unit operations described in Figure 1.1 represents the chemical n reactor? You should have identified the "conversion step
An introduction to biotechnological innovations in the chemical industry mera +ornain Mtrna FL heating separaton Figure 1.1 Example of a simple production process with eight unit operations In practice, production processes are usually rather more complex. Raw materials are sually impure and thus some pre-purification steps may be required. Obviously impurities in the raw materials will incresae the probability of impurities and byproducts byproducts occuring in the output stream from the chemical conversion step. Ev using pure raw materials, most chemical conversion are incomplete and often lead to auxiliary the formation of undesirable byproducts. Furthermore often additional (auxiliary) materials are used (for example catalysts, specific solvents), which have to be separat from the desired product, Thus, in typical production processes a large number of separation steps are required To improve the efficiency of the process, raw materials and auxliary chemicals are recycled providing it is economically viable. Similarly ways are sought to find uses for byproducts and intermediates. This usually involves using them as feeds for further reactions. Invariably, production processes produce waste streams. These must be ble state before being disposed of. This is relating to chemical production processes in which the compounds produced may be incompatable or toxic to living systems and can thus cause pollution problems. Increasing regulatory and technical burdens are being place on chemical process operators to ensure that such environmental problems do not arise from their In biotechnological processes, the conversion of raw material to product is usually performed by micro-organisms, or parts of micro-organisms(eg enzymes) known as a fermentation or bioconversion processes respectively. On a large scale, the conversion biotechnological is generally carried out in a so-called bioreactor. The conditions under which the processes are conversion is done are generally very gentle with regards to temperature, pressure and mo. pH, when compared to those in a chemical process. Other advantages of environmenal biotechnological production processes include high reaction specificity and selectivity therefore fewer byproducts, and the need for relatively few reaction additives. Another important difference between a chemical and a biotechnological production process is that the latter type is closely related to naturally occurring processes byproducts may only be carbon dioxide and water. The implementation of biotechnological production methods can, therefore, be seen as an environmentally friendly production strategy. We shall compare chemical and biotechnological catalysis in more detail in the next chapter Within the chemical industry, micro-organisms and enzymes are often used as catalysts It is possible for a unit operation in an essentially chemical production process to be a biochemically catalysed step: giving rise to a mixed chemical/biochemical production process. The products of these reactions include organic chemicals, solvents, polymers, biochemical pharmaceuticals, and purfumes Mixed chemical /biochemical production processes processes are continuously innovated and optimised, mainly for economical reasons
An introduction to biotechnological innovations in the chemical industry Figure 1.1 Example of a simple production process with eight unit operations. In practice, production processes are usually rather more complex. Raw materials are usually impure and thus some pre-purification steps may be required. Obviously impurities in the raw materials will incresae the probability of impurities and byproducts occuring in the output stream from the chemical conversion step. Even using pure raw materials, most chemical conversion are incomplete and often lead to the formation of undesirable byproducts. Furthermore often additional (auxiliary) materials are used (for example catalysts, specific solvents), which have to be separated from the desired product, Thus, in typical production processes a large number of separation steps are required. To improve the efficiency of the process, raw materials and auxiliary chemicals are recycled providing it is economically viable. Similarly ways are sought to find uses for byproducts and intermediates. This usually involves using them as feeds for further reactions. Invariably, production processes produce waste streams. These must be brought to an acceptable state before being disposed of. This is especially a concern relating to chemical production processes in which the compounds produced may be incornpatable or toxic to living systems and can thus cause pollution problems. Increasing regulatory and technical burdens are being place on chemical p'ocess operators to ensure that such environmental problems do not arise from their operations. In biotechnological processes, the conversion of raw material to product is usually performed by micm-organisrns, or parts of micro-organisms (eg enzymes) known as a fermentation or bioconversion processes respectively. On a large scale, the conversion is generally carried out in a so-called bioreactor. The conditions under which the conversion is done are generally very gentle with regards to temperature, pressure and pH, when compared to those in a chemical process. Other advantages of biotechnological production processes include high reaction specificity and selectivity (therefore fewer byproducts), and the need for relatively few reaction additives. Another important difference between a chemical and a biotechnological production process is that the latter type is closely related to naturally occurring processes: byproducts may only be carbon dioxide and water. The implementation of biotechnological production methods can, therefore, be seen as an environmentally friendly production strategy. We shall compare chemical and biotechnological catalysis in more detail in the next chapter. Within the chemical industry, micruorganisms and enzymes are often used as catalysts. It is possible for a unit operation in an essentially chemical production process to be a biochemically catalysed step: giving rise to a mixed chemical/biochemical production process. The products of these reactions include organic chemicals, solvents, polymers, pharmaceuticals, and purfumes. Mixed chemical/biochemical production processes are continuously innovated and optimised, mainly for economical reasons. bypm~cts auXiliar~ mabe~ bD&&mbgM processes are mom enviro""'~~\ m,xed chemical/ biochemical pro^^^
Chapter 1 1.3 Choice of production process economic It is possible to produce many chemical moieties(partly) by means of bi technological nsiderations production processes. For example, ethene(C)H commands a large market and is produced from fossil oil. This chemical can also be produced from ethanol, which in building unit for the petrochemical industry from which several other intermediates and end products such as plastics are produced. The biotechnological production method is, however, for economical reasons still not used in practice. The costs of producing ethene from sugar via ethanol are relatively too high. This is partly due to the cost of the raw materials and the product yields on the two different substrates. The eparation of ethanol from the aqueous fermentation liquid is also relatively expensive Unfortunately micro-organisms that make large amounts of ethene directly from glucose have not been found. Nevertheless, the biotechnological production method may become the cost effective option as fossil energy sources become depleted and relatively more expensive. Other chemicals such as gluconic acid cannot be produced by petrochemical production methods. Gluconic acid is used in the pharmaceutical industry and even as an addition to concrete. Gluconic acid can be produced from glucose, derived from potato starch, using the bacterium Gluconobacter or the fungus Aspergillus. These micro-organisms are able to modify glucose rapidly to gluconic acid, which is slowly consumed again. In this way gluconic acid is temporarily accumulated in the fermentation fluid. Technically, it specificity of would be possible to perform this process chemically starting from glucose, but in this thus no undesired byproducts are formed. For the same reason biotechnological production processes are preferred if optically pure chiral compounds, such as L-configuration of a certain amino acid, has to be produced. The price of such products production of organic acids andam sive. In later chapters of this text we consider the is, however, relatively more exper ino acids in some detail biodegradable Another example of producing a chemical in bulk from sugar with the help of a products micro-organism is the polymer polyhydroxybutyric acid. Many micro-organisms accumulate this compound as a reserve material. This polymer could be substitute for polyester or polypropene plastics. The big advantage of polyhydroxybutyric acid is that it can be degraded microbially. Products such as plastics that have been used for shorter or longer times and when they are not needed any more are brought back into the environment. However, when retumed to the environment they are not readily biodegraded (they are recalcitrant)and thus accumulate. The accumulation of materials that are not readily returned to natural geocycling is of major concern. In a world where mankind has become aware that more sustainable environmental practice have to be used to prevent pollution, biotechnology will become more and more important. A first obvious consequence of such considerations is that we should not only look at the costs of the product from an economic point of view, but that we must consider the costs of the production process in a broader sense. We must take into account the raw materials used, the amount of energy invested and the possibility to design alternatives, more environmentally friendly processes. In other words, we should not only look at the desired product, but we must consider the total life cycle of the product. The design manage f a production process taking into account these aspects is often referred to as integral life cycle management
4 Chapter 1 economic COnsidetations specificity of readon biodegradable pro&* 1.3 Choice of production process It is possible to produce many chemical moieties (partly) by means of biotechnological production processes. For example, ethene (Cd-h) commands a large market and is produced from fossil oil. This chemical can also be produced from ethanol, which in turn can be produd by micro-organisms using agricultural wastes. Ethene is a 'building unit' for the petrochemical industry from which several other intermediates and end products such as plastics are produced. The biotechnological production mthM is, however, for economical reasons still not used in practice. The costs of producing ethene from sugar via ethanol are relatively too high. This is partly due to the cost of the raw materials and the product yields on the two different substrates. The separation of ethanol from the aqueous fermentation liquid is also relatively expensive. Unfortunately micmrganisms that make large amounts of ethene directly from glucose have not been found. Nevertheless, the biotechnological production method may become the cost effective option as fossil energy sources become depleted and relatively more expensive. Other chemicals such as gluconic acid cannot be produced by petrochemical production methods. Gluconic acid is used in the pharmaceutical industry and even as an addition to concrete. Gluconic acid can be produced from glucose, derived from potato starch, using the bacterium Gluconobucfer or the fungus Aspergillus. These micro-organisms are able to modify glucose rapidly to gluconic acid, which is slowly consumed again. In this way gluconic acid is temporarily accumulated in the fermentation fluid. Technically, it would be possible to perform this process chemically starting from glucose, but in this case the biological method is preferred as the specifity of this reaction is very high and thus no undesired byproducts are formed. For the same reason biotechnological production processes are preferred if optically pure chiral compounds, such as Lconfiguration of a certain amino acid, has to be produced. The price of such products is, however, relatively more expensive. In later chapters of this text we consider the production of organic acids and amino acids in some detail. Another example of producing a chemical in bulk from sugar with the help of a micro-organism is the polymer polyhydroxybutyric acid. Many micmorganisms accumulate this compound as a reserve material. This polymer could be substitute for polyester or polypropene plastics. The big advantage of polyhydroxybutyric acid is that it can be degraded microbially. Products such as plastics that have been used for shorter or longer times and when they are not needed any more are brought back into the environment. However, when returned to the environment they are not readily biodegraded (they are recalcitrant) and thus accumulate. The accumulation of materials that are not readily returned to natural geocycling is of mapr concern. In a world where mankind has become aware that more sustainable environmental practice have to be used to prevent pollution, biotechnology will become more and more important. A first obvious consequence of such considerations is that we should not only look at the costs of the product from an economic point of view, but that we must consider the costs of the production process in a broader sense. We must take into account the raw materials used, the amount of energy invested and the possibility to design alternatives, more environmentally friendly processes. In other words, we should not only look at the desired product, but we must consider the total life cycle of the product. The design of a production process taking into account these aspects is often referred to as integral life cycle management
An introduction to biotechnological innovations in the chemical industry The application of the principles of integrated life cycle management, generally favours the replacement of products dependent upon conventional chemical and physical processes by biotechnological products and processes. As we described earier, most biotechnological processes use biological (renewable) feedstocks and energy sources and the products are also compatable with biological (living) system. These products re readily biodegradable and retumed to the natural geocoding and, as a consequence, do not pose the same intensity of pollution caused by the recalcitrant materials and byproducts generated by physico-chemical processes. Biotechnology therefore offers a more environmentally friendly and sustainable approach to fulfilling the needs of society. It can achieve this by, for example, offering ermative routes to the manufacture of products hitherto made by potentially nvironmentally damaging routes. Alternative, it enables the production of novel roducts, which are less environmentally damaging than products made via conventional chemical routes. We will use two examples to illustrate these principles nitrogen fixation Nitrogen fixation via the Haber-Bosch process is a well established chemical pI). The which dinitrogen gas(N2) and hydrogen are combined to produce ammonia (NH3).The major use of this produce is as a nitrogen fertiliser. Several million tonnes are produced annually. On the positive side of ammonia(usually as an ammonium salt)has undoubtedly increased the yields of crops. In strictly limited economic terms,the increase in crop yields achieved by the use of ammonia from the Haber-Bosch process more than outweighs the cost of producing the ammonia. with this limited perspective, the Haber-Bosch process is undoubtedly successful. If, however, we take an integrated life management approach, the issue is not so clear cut. The reduction of dinitrogen is an energy expensive process. Energy is needed to split the stable N=N bond. In the Haber-Bosch process, high temperatures(400C)and pressures are used to achieve significant conversions. This energy input is invariably derived from non-renewable energy sources. However, the environmentally damaging eutrophication effects of this activity is not limited to the production of ammonia. Much of the mmonia-based fertilisers applied to land is washed out (leached)from soils. This ends up in rivers and in impounded water, causing eutrophication (increase in organie content). The consequence of this, is these waters support greater blooms' of algae, which in time die and decompose. This decomposition is accompanied by the onsumption of oxygen, which tends to lead to anoxia. Thus the waters lose amenity value because they no longer support fish life, are more difficult to treat to become potable; they become odourous and are no longer suitable for bathing. Thus, if one adds to the cost of the Haber-Bosch process the true environmental costs, then the virtue of this process is less than clear cut. Biotechnology, however, offers an alternative approach to achieving the same objective as the Haber-Bosch process. It has long been known that bacteria capable of utilising atmospheric nitrogen can supply plants with nitrogen in a form that the plants can use and very little of this "fixed"nitrogen is leached from the soil. In essence, what biotechnology offers is the potential to widen the range of crops that can be supported sing biologically generated nitrogen fertilisers. These biological nitrogen-fixers use ological energy sources(carbohydrates)to drive fixation and do not lead to the same levels of entrophication as does the application of chemically produced ammonia Even on the rather simplified arguments described here, it should be clear that biotechnological approaches are generally more en vironmentally friendly and that we can apply biotechnological strategies to inorganic, as well as organic chemicals. We
An introduction to biotechnological innovations in the chemical industry 5 The application of the principles of integrated life cycle management, generally favours the replacement of products dependent upon conventional chemical and physical processes by biotechnological products and processes. As we described earlier, most biotechnological processes use biological (renewable) feedstocks and energy sources and the products are also cornpatable with biological (living) system. These products are readily biodegradable and returned to the natural geocycling and, as a consequence, do not pose the same intensity of pollution caused by the recalcitrant materials and byproducts generated by physicochemical processes. Biotechnology therefore offers a more environmentally friendly and sustainable approach to fulfilling the needs of society. It can achieve this by, for example, offering alternative routes to the manufacture of products hitherto made by potentially environmentally damaging routes. Alternative, it enables the production of novel products, which are less environmentally damaging than products made via conventional chemical routes. We will use two examples to illustrate these principles. Nitrogen fixation via the Haber-Bosch process is a well established chemical process in which dinitrogen gas (N2) and hydrogen are combined to produce ammonia (NEG). The major use of this produce is as a nitrogen fertiliser. Several million tonnes are produced annually. On the positive side, use of ammonia (usually as an ammonium salt) has undoubtedly increased the yields of crops. In strictly limited economic terms, the increase in crop yields achieved by the use of ammonia from the Haber-Bosch process more than outweighs the cost of producing the ammonia. With this limited perspective, the Haber-Bosch process is undoubtedly successful. If, however, we take an integrated life management approach, the issue is not so clear cut. The reduction of dinitrogen is an energy expensive process. Energy is needed to split the stable N=N bond. In the Haber-Bosch process, high temperatures (400°C) and pressures are used to achieve significant conversions. This energy input is invariably derived from non-renewable energy sources. However, the environmentally damaging effects of this activity is not limited to the production of ammonia. Much of the ammonia-based fertilisers applied to land is washed out (leached) from soils. This ends up in rivers and in impounded water, causing eutrophication (increase in organic content). The consequence of this, is these waters support greater 'blooms' of algae, which in time die and decompose. This decomposition is accompanied by the consumption of oxygen, which tends to lead to anoxia. Thus the waters lose amenity value because they no longer support fish life, are more difficult to treat to become potable; they become odourous and are no longer suitable for bathing. Thus, if one adds to the cost of the Haber-Bosch process the true environmental costs, then the virtue of this process is less than clear cut. Biotechnology, however, offers an alternative approach to achieving the same objective as the Haber-Bosch process. It has long been known that bacteria capable of utilising atmospheric nitrogen can supply plants with nitrogen in a form that the plants can use and very little of this "fixed" nitrogen is leached from the soil. In essence, what biotechnology offers is the potential to widen the range of crops that can be supported using bioiogically generated nitrogen fertilisers. These biological nitrogen-fixers use biological energy sources (carbohydrates) to drive fixation and do not lead to the same levels of entrophication as does the application of chemically produced ammonia. Even on the rather simplified arguments described here, it should be clear that biotechnological approaches are generally more environmentally friendly and that we can apply biotechnological strategies to inorganic, as well as organic chemicals. We nitrogen fixation eutrophication