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_'{R, SOIL, AND WATER are vital to life on _lthis planet. We must protect these re- - _ sources and use them wisely our sur- vival as a species depends on them. Despite recent impressive strides in improving the en- vironment, evidence is overwhelming that more effective action must be taken to address such critical issues as acid rain, hazardous waste disposal, hazardous waste landfills, and ground- water contamination. It is also vital that we assess realistically the potential health and en- vironmental impacts of emerging chemical prod- ucts and technologies. The problems are clearly complex and demand a broad array of new research initiatives. Technological activities of which chemical manufacture and processing are key parts- begin with the extraction of raw materials from the environment. They then proceed through numerous steps-processing, storage, handling, (a Extraction \\ / .~; Dispose/ ...... I' ~N FRONTIERS IN CHE^~AL E.~llVEERIA7G transportation, and use and finally end with the ultimate return of processed materials or their residues to the environment (Figure 7.1~. The resulting redistribution of chemicals within the environment may have adverse impacts. Harmful compounds of certain elements (e.g., nitrogen, sulfur, halogens) may be widely mo- bilized. Other elements may be converted from innocuous forms (e.g., mercuric sulfide in cin- nabar) to highly toxic forms (e.g., methyl mer- cury). Chemical engineers are involved in all aspects of chemical manufacture and process- ing; therefore, it should be their responsibility to safely manage chemicals in the environment. Environmental and safety concerns will be cru- cial challenges to the chemical engineers of the future. No other group is better trained or more centrally positioned in the industrial world to be the cradle-to-grave guardian of chemicals. Our approach to environmental and safety Production / ENVIRONMENTAL TRANSPORT AND TRANSFORMATION ~ EXPOSURE AND EFFECTS / , ,~' Storage ~ _~ Transportation FIGURE 7.1 Life cycle of chemicals in the environment.

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ENVIRONMENTAL PROTECTION, PROCESS SAFETY, H^474~LS WASTES MANAGEMENT DECISIONS Introduction of new chemicals or products into the environment Introduction or mod fication of species in the environment Technology Utilization (Existing or new methods) Changes in resource utilization (urban development, fuels, etc) 1 RISK ASSESSMENT AND MANAGEMENT Determination of risk to susceptible populations Identification of mitigation measures 1 , 1 I l 1 EFFECTS ON HEALTH AND WELFARE Changes in target organs and the associated health effects Changes in the physical environment (materials, visibility, etc) RESPONSE OF ECOSYSTEMS Physical Changes -Nutrient and energy flows -Physical structure of system -Transport and Transformation Biological Changes -Change in population size -Mod fications to interactions -Indirect effects on species diversity EXPOSURE ASSESSMENT Exposure of human population Exposure of animals and plants of concern to humans FIGURE 7.2 The effects of human activities on the environment. problems must change from reactive to proac- tive; in other words, instead of responding to crisis and public pressures, we must anticipate and prevent problems. This will require an understanding of the detailed chemistry and physics of processes at the molecular level. Such basic understanding is crucial if we are to design plants that are safer and that cause less pollution, develop better ways to manage and detoxify hazardous waste, and predict the fate of chemicals in the environment as well as the effects of chemicals on humans and ecosystems. Figure 7.2 diagrams how human activities can affect environmental quality and human health. Introduction of new chemical products, adop- tion of different technologies, or changes in resource utilization can lead to emissions that affect the physical, chemical, or biological re- sponses of the receiving ecosystems. This can ~07 in turn affect human beings and other resources. A risk assess- ment of the potential health and welfare effects of such changes can indicate whether and to what extent mitigation measures should be taken, or original decisions rethought. Each of the boxes in the diagram, although greatly simplified, represents a cluster of questions that require answers from environmental research. IMPACT ON SOCIETY OF CHEMICALS IN THE ENVIRONMENT A number of environmental issues have received widespread publicity (Table 7.1), from major accidents at plants (e.g., Seveso and Bhopal) to the global and regional impacts associated with energy utilization (e.g., carbon dioxide, acid rain, and photo- chemical oxidants), the improper disposal of chemical waste (e.g., Love Canal and Times Beach), and chemicals that have dis- persed and bioaccumulated af- fecting wildlife (e.g., PCBs and DDT) and human health (e.g., cadmium, mer- cury, and asbestos). As a consequence, much of the public has come to believe that most chemicals are haz- ardous. A recent poll by the Roper Organization revealed that two out of three American citizens expect a major chemical disaster, resulting in thousands of deaths, within the next 50 years.) The poll also found that a high proportion of the public lacked confidence that industry would deal openly with them. A public attitude toward exposure to chemicals is developing that can be summed up by the words, "no risk." But, as a judge recently stated, "In the crowded conditions of modern life, even the most careful person cannot avoid creating some risks and accepting others. What one must not do, and what I think a careful person tries not to do, is to create a risk which is substantial."2

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FRONTIERS I1Y CH~E1~L ENGINEERI.~G TAR} F. 7.1 Some Well-P~ icize`1 Fnvironmentn1 I. Global Regional Urban Site-specific Chlorofluorocarbons and their effect on ozone in the upper atmosphere Carbon dioxide and other '~greenhouse" gases (e.g., methane) and their effect on global temperature DDT Polychlorinated biphenyls (PCBs) Acid rain (NOx, SOx) Agricultural wastewaters (Kesterson Wildlife Refuge, Chesapeake Bay) Airborne lead from automobile exhausts Carbon monoxide from automobile exhausts Photochemical oxidants, particularly ozone (Los Angeles) Sulfur oxides (SOx) and particulate matter (London, Donora) Dioxins (Seveso, Love Canal, and Times Beach) Methyl isocyanate (Bhopal) Methyl mercury (Minamata) Cadmium (Itai-Itai) Indoor air (Formaldehyde, asbestos, NO., CO) What is a substantial risk? How safe is safe enough? These are questions that trouble the public, industry, and regulators alike. Scientific understanding and the available data are inad- equate to evaluate the true risk to individual safety, or the true risk of damage to human health or the environment, from exposure to most chemicals or to chemical plant or disposal operations. Yet, legislators and regulators can- not wait for all the data to come in before they start to provide the public with the protection it is demanding. Laws have been passed and regulations have been developed that require government approval for production of new chemicals, design and operation of chemical plants, workplace exposures, certain product uses, quantities and concentrations of chemicals in effluent streams, and disposal of waste and by-product streams. But because of the uncer- tainties, some regulations have been written to protect against the effects of extremely unlikely worst-case scenarios, resulting in a misalloca- tion of resources, reduced technical innovation, and excessive costs. At the same time, other, less visible hazards that might be the focus of appropriate regulation have been overlooked. This situation must be corrected. Society needs a clean and safe environment. It also needs to capitalize fully on new developments in chemistry, biotechnology, and materials sci- ence, if the United States is to retain techno logical leadership and international competi- tiveness in major segments of industry. Some of the economic and social costs related to major environmental issues are discussed in the following sections. Chemical Industry Safety The U.S. chemical and petrochemical indus- try safety record is generally good. The National Safety Council's 1985 data show that the chem- ical industry worker is only one-fourth as likely to have a fatal on-thejob accident as the average U.S. employees The Bureau of Labor Statistics indicates that the 1984 chemical industry rate for lost work days resulting from occupational injury was 2.4 per 200,000 man-hours, compared to 4.7 for manufacturing as a whole and 3.7 for all private sector employments Over the past decade, annual fatalities from hazardous chem- ical accidents have numbered around 40, while highway fatalities have numbered around 40,000.3 Nevertheless, accidents and unintended chemical releases pose serious financial risks to the chemical and petrochemical industry. In 1984 there were five major accidents in the hydrocarbon-chemical industries, totaling an estimated loss of $268 million.5 Hundreds of lesser accidents occur yearly. The total annual cost to the industry of accidents and unintended chemical releases is difficult to quantify. It includes significant costs owing to interruption

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ENVIRONMENTAL PROTECTIOA7, PROCESS SAFETY, HA718~US WASTES ~E:~-~ ~ FIGURE 7.3 In 1984, 14 years after the passage of the Clean Air Act, significant areas of the United States were still in violation of National Ambient Air Quality Standards (NAAQS) for ozone. Courtesy, Environmental Protec- tion Agency. of business as well as major liability and liti- gation costs associated with injuries, deaths, property damage, and insurance premiums. It also includes losses of product and feedstock that are direct profit losses for the manufacturer. One estimate is that U.S. industry spent $7.7 billion in 1985 for protecting worker safety and health;6 the total annual cost of accidents and unintended chemical releases by the U.S. chem- ical and petrochemical industries is surely many billions of dollars. Costs associated with increased government regulation are also difficult to quantify. Public concern in response to chemical release acci- dents affects regulators and community policy groups. It is evident that the U.S. chemical industry is already spending large amounts of money to avoid accidents and to deal with their consequences when they occur; these costs are borne in part by the consumers. Continued expenditures are likely as industry strives to achieve an "acceptable" level of public safety throughout all chemical industry operations. Combustion of Fuels for Power Generation and Transportation The burning of fuel for power generation and transportation presents some of the most long standing and important problems in environmental protection. Fossil fuels are used in such magnitude that emissions from combustion sources have a major impact on urban, regional, and global air quality. Combustion- generated pollutants are derived from contaminants in the fuel such as sulfur, nitrogen, and in- organic compounds, from incom- plete combustion of the fuel, and from the high-temperature reac- tion of nitrogen with oxygen in the air heated by combustion processes. These pollutants are emitted both in gaseous form (e.g., the oxides of nitrogen-the sum of NO and NO2, denoted as NOX-sulfur dioxide, and un- burned hydrocarbons) and in particulate form (e.g., fly ash and soot). The 1970 Clean Air Act and its amendments are directed at reducing combustion-generated emissions through the establishment of National Ambient Air Quality Standards (NAAQS) for oxides of sulfur and nitrogen, carbon monoxide, particulate matter, lead, and ozone. While sub- stantial reductions in urban levels of carbon monoxide, sulfur oxides, and particulate matter have been achieved over the past 15 years, ozone levels, controlled by an intricate chem- istry involving organic gases and oxides of nitrogen, have proved to be more resistant to control (Figure 7.31. Large-scale air quality problems arising from combustion-generated emissions, such as acid rain (Figure 7.4), re- gional hazes, and volatile toxic compounds, have also assumed prominence and will likely be the targets of future legislation. Adding fluidized gas desulfurization to coal- fired generating plants is estimated to add 15- 25 percent to their total capital costs, or up to $125 million on a typical 500-megawatt unit.7 Since the cost of reducing emissions by modi- fying the combustion process is usually an order of magnitude lower than that of cleaning the fuel before burning or removing the pollutants from the exhaust gases, there are significant challenges to develop clean, fuel-efficient com

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/ bustion processes as well as to design more economical processes for fuel cleaning prior to combustion and for destroying or removing the residuals from postcombustion gases. Hazardous Waste Management The disposal of hazardous waste may well have become the Achilles' heel of the American manufacturing industry. More than 300 million tons of hazardous waste are generated annually by about 14,000 installations in the United States. About 14.7 billion gallons of hazardous waste is disposed of in or on the land each year, FRONTIERS IN CHEMICAL ENGINEERING /'/"/ ~ ;~ \"` 5. - ~` ~ 622-~__:i ~ ~ , ~-; \510 5'15-/ ~ ~ ~ Nt W? t6.s2 ~,' ~~ :5.33- ~ ~ f 5.47 ~ \~ e ~.51 / I ~ L _ aim\\! ~ \ ~ ~ ) :'-41\ - _ 4 87 .~5.67 ~1 5.g5 `_! FIGURE 7.4 Annual mean value of pH (acidity) in precipitation, weighted by the amount of precipitation in the United States and Canada for 1980. The low pH values seen in the eastern United States and Canada reflects the high acidity of the rainfall and other precipitation in this region. This geographic pattern of acid rain correlates with the emission and transport of sulfur dioxide from coal-burning plants. From U.S./Canada Work Group #2, Atmospheric Science and Analysis, U.S. Environmental Protection Agency, Washington, D.C., 1982. while around 500 million gallons are incinerated. Of the total quantity of hazardous waste gen- erated, manufacturers account for 92 percent. It has been estimated that the chemical industry alone generates 71 percent of the manufacturer's total.8 The Congressional Budget Office has estimated that the 1984 amendments to the Resource Conservation and Recovery Act could increase industrial compliance costs from be- tween $4.2 billion and $5.8 billion in 1983 to between $8.4 billion and $11.2 billion in 1990, depending on the level of waste reduction achieved by industry.9 A variety of methods have been used over

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E'i\ YIRONI~1~ TAL PROTECTION, PROCESS SAFETY, HAZARDS US 'WA S TES the past 100 years to bury hazardous waste. Many of these burial sites now pose a threat to the health of nearby residents and, more broadly, to the nation's underground water supply (Fig- ure 7.5~. For example, recent studies by the state of California have shown that there are widespread threats to groundwater in Califor- nia's Silicon Valley; Santa Clara County leads the nation in the number of sites on the National Priority List, most of which are associated with the electronics industry.~ The U.S. Congress Office of Technology Assessment has recently projected that there are 10,000 sites nationwide that belong on the National Priority List of toxic waste dumps. ~ ~ In 1980, Congress appropriated $1.6 billion for a 5-year Superfund program. The original Superfund legislation viewed cleanup of haz- ardous waste sites as a relatively short-term program and anticipated that waste could be contained for several decades by methods such as building slurry walls and clay caps to elimi- nate diffusion of buried waste into subsurface Well :~_ Disposal ~ ~ Pond Deep-Well Injection waters. After a few years of pursuing such methods, it is clear that they do not provide a solution to the problem of containment of waste in existing landfills; slurry walls leak and clay caps crack. It is also becoming increasingly clear that it will require decades to accomplish an adequate cleanup of hazardous waste sites nationwide. Thus, when the Superfund act was reauthorized in 1986, a significant focus was on the use of new technologies to decontaminate soil and groundwater and to provide for long- term containment of wastes (i.e., through en- capsulation). The level of expenditure could be as high as $10 billion over the next 5 years. When one takes the cost of industrial com- pliance with RCRA to handle currently gener- ated wastes and adds the cost of Superfund to clean up the wastes of the past, it becomes obvious that there are strong incentives for technology development in the area of waste minimization and treatment, and many oppor- tunities for research and employment for chem . . . 1ca1 engineers. Spills Buried Wastes it,' '~4 th2`-'2~ 2 2-2 l"2 2' ~ Well ~ A\ FIGURE 7.5 Past methods of waste disposal threaten water supplies today. Reprinted from Opportunities in Chemistry, National Academy Press, 1985.

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DESIGN OF INHERENTLY SAFER AND LESS POLLUTING PLANTS AND PROCESSES Few basic decisions affect hazard potential or have more of an impact on environment than the initial choice of technology. Thus, when designing chemical manufacturing processes, it is important to select sequences of chemical reactions that avoid the use of hazardous feed- stocks and the generation of hazardous chemical intermediates. It is necessary to find reaction conditions tolerant of transient excursions in temperature, pressure, or concentration of chemicals and to use safe solvents when ex- tracting reaction products during purification steps. Finally, it is important to minimize stor- age and in-process inventories of hazardous substances. The term "inherently safer plants" has been used to describe this approach. One further consideration in the design of a new process or plant is whether it is going to generate polluting effluents or hazardous wastes. Good design should result in waste minimization in a manufacturing process or plant. Traditional analyses of process economics might show that inherently safer and less pol- luting plants are less efficient in terms of energy or raw materials usage. Indeed, chemical plants have been designed in the past principally to maximize reliability, product quality, and prof- itability. Such issues as chronic emissions, waste disposal, and process safety have often been treated as secondary factors. It has become clear, however, that these considerations are as important as the others and must be addressed during the earliest design stages of the plant. This is in part due to a more realistic calculation of the economics of building and operating a plant. When potential savings from reduced accident frequency, avoidance of generating hazardous waste that must be disposed of, and decreased potential liability are taken into con- sideration, inherently safer and less polluting plants may prove to cost less overall to build and operate. And in any case, if the American public is not convinced that chemical plants are designed to be safe and environmentally benign, then the fact that they operate economically will be of little consequence to the public's FRO:~RS IN CAL E1YGINEER~G decision on whether to allow their construction and operation. The chemical reaction pathways chosen for a manufacturing process profoundly influence chemical plant safety because they determine the nature and amounts of all substrates, prod- ucts, and reagents and implicitly govern the design and operation of all hardware. The ulti- mate goal of chemical engineering research to provide inherently safer plants should be to elucidate the connection between process path- ways and plant safety and to translate this connection into a quantitative form amenable to engineering design calculations. The array of chemicals, reactions, processes, and types of physical equipment used in industry is exceed- ingly diverse and constantly evolving. To effec- tively address the need for inherently safer plants, chemical engineering research must be focused on fundamental issues that span the entire range of processing activities, from elu- cidating detailed reaction mechanisms to un- derstanding and predicting the gross response of coupled equipment. The goal of such fun- damental research would be to develop the tools needed to define, discern, and assess the safety issues associated with a given process design and its alternatives. New approaches to the design of commercial chemical syntheses should be pursued. A chem- ical synthesis tree graph with a high-value prod- uct at its apex, lower-value raw materials at the base, and reaction steps as nodes connecting all branches offers a basis for quantitative as- sessment of feasible and economic process al- ternatives. It could also serve to define the safety and environmental impact of a pathway and offer a basis for safe designs that produce minimal wastes. Tree graphs could be particu- larly helpful in evaluating the process safety implications of highly selective synthesis routes. Near the apex of the chemical synthesis tree graph materials that might be used in chemical reactions are of highest value. Overall raw material and energy costs are lowest for those pathways that use the most selective reactions to achieve the highest yield of the desired product. However, these selective reactions often require the handling and storage of more reactive, and hence more hazardous, chemicals.

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E1\'Y~.~TAL 6~.N ~ PROCESS SAFETY HAZARDOUS -A7.~/ BEES For example, in the synthesis of Carbaryl at Bhopal, a process that required storage of large quantities of the reactive intermediate methyl isocyanate was used, rather than a less flexible and more expensive straight-through reaction scheme with a minimal inventory of methyl isocyanate. Developing the methodology of us- ing process safety and environmental factors in synthesis tree graphs could provide a better framework for future plant design. Most accidents in chemical plants occur when the plant is not operating at a steady state for example, when it is starting up or shutting down or when a transient of temperature, pressure, or reactant concentration occurs. Fundamental research in non-steady-state process control and the management of process transients is there- fore warranted. Design methodology poses a related research issue. It is obviously easier for the designer of a plant or individual reactor to envision how the equipment will operate during the normal production mode than to envision how it will operate under a host of potential scenarios that derive from process transients. The safety of chemical plants and reactors could CH H C2H6 H,O,OH CH3 C ~20 CHO CO / CH3 O H | H,O,OH | H H.O.OH ~ CH3CHO- H. O. OH, CH3CO ~ CH3 C H O. OH , CH3, CHoO, CHO C2H3 O2,H H OH C9H2 - CO2 ~2CH2 CH2O, CHO O | OH 1 o ~ CH2CO H ~ CH3 FIGURE 7.6 Mechanism of methane combustion. ~3 be improved if designers had the means to envision the complete reaction topography and to assess the consequences of straying from normal operations. This would involve devel- oping design tools that would incorporate chem- ical pathway information more systematically into classical engineering design methods for reactors and associated equipment. COMBUSTION Many of the environmental issues listed in Table 7.1 are intimately related to combustion. Combustion contributes significantly to emis- sions of pollutants into the environment, with effects ranging from those pertaining to indoor air pollution to those affecting global climate. For this reason, combustion has been singled out to illustrate the progress that can be made in resolving environmental issues through a sustained fundamental research program and to demonstrate the potential added benefits of continued in-depth study of the physical and chemical processes underlying combustion. Hydrocarbons and Fuel- Bound Nitrogen The burning of fuel in a prac- tical combustion system, such as a power plant boiler or the cyl- inder of an internal combustion engine, is at first glance very simple: a mixture of hydrocarbon and air is ignited and burned to carbon dioxide and water. On closer examination this burning turns out to be one of the most complex processes in all engi- neering. For example, the com- bustion of the simplest hydro- carbon fuel, methane, involves more than 50 chemical reactions (Figure 7.61. During the past four decades, major progress has been made in developing a mechanis- tic understanding of the combus- tion of methane and C-2 hydro- carbons and their derivatives. Rate constants of many individ

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ual free-radical reactions have been measured, and a good num- ber of those not measured can be estimated from thermochem- ical kinetics and unimolecular re- action theory. Major unknowns in the mech- anism by which a hydrocarbon fuel burns concern the pyrosyn- thesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hy- drogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. Nitrogen oxide emissions from furnaces and boilers come mostly from oxidation of the nitrogen atoms in the fuel, whereas in internal combustion engines these emissions are derived largely from oxidation of atmospheric nitrogen. Burners of advanced design currently reduce the emissions of nitrogen oxides by a factor of 2 from uncon- trolled combustion systems by staging the ad- dition of oxygen to produce an initial fuel-rich regime in which the bound nitrogen is partially converted to N2 (Figure 7.71. Potentially greater reduction in nitrogen oxides can be attained by adding hydrocarbons downstream of the fuel. This is called reburning (Figure 7.81. To deter- mine the optimal sequence of air and fuel addition requires detailed knowledge of both the fuel nitrogen chemistry and the hydrocarbon chemistry. The development of staged combustors for the control of nitrogen oxides is constrained partly by the formation of PAHs and soot (Figure 7.9~. The PAHs are potential carcino- gens whose biological activity depends strongly on their molecular structure. It is postulated that they are formed under locally fuel-rich conditions by the successive addition of C-2 through C-5 hydrocarbons to aromatic rings followed by ring closure. On the other hand, a staged combustor cannot be operated on too lean a fuel mixture because formation of nitro- gen oxides is favored under this regime. Con ~~A'~RS rN ~E,~IC:~1L ~.7~/~ll\TEERIlYG SECONDARY COAL AND /y AIR PRIMARY AIR 1 ~/ INTERIOR MUTT-STAGE BURNER WALL ~O~yC~ \ ~/ / FIGURE 7.7 Schematic of a 10w-NOx/SOx pulverized coal burner. The addition of oxygen is staged to produce an initial fuel-rich zone in the burner that results in reduced emissions of nitrogen oxides. tinned experimental and theoretical study of the combustion chemistry of higher molecular weight hydrocarbons should provide the understanding needed for the design of combustors in which the fuel/oxygen regime is selected to minimize emissions of PAHs and nitrogen oxides. Soot Combustion processes are a major source of particles emitted to the atmosphere. Particles formed in combustion systems fall roughly into X~ FUEL MOLECULE CONTAINING FUEL NITROGEN ATOMS | 0:,, NO COMBUSTION NH - N2 FIGURE 7.8 NOx control in combusion by reburning. Ad- dition of hydrocarbons (CHn) late in the combustion process leads to the reduction of nitrous oxide (NO) to nitrogen gas (No)

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Ei\~.~ENTAL PROTECTION, PROCESS SAFETY, ^~AY,4~0US -BASTES Hydrocarbon , C4Hs + C2H2 ~ [2 Fuel Butadienyl Acetylene Radical ~ +C2 ~ Pyrene Phenanthrene Benzene i+C4 =\ +C4 ~ +C2 [4 Naphthalene Acenapthylene FIGURE 7.9 Mechanism of formation of polycyclic aromatic hydrocarbons (PAHs) during combustion. two categories. The first, referred to as soot, consists of carbonaceous particles formed by pyrolysis of the fuel molecules. The second, referred to as ash, is composed of particles derived from noncombustible constituents in the fuel and from heteroatoms in the organic structure of the fuel. Soot can be produced in the combustion of gaseous fuels and from the volatilized compo- nents of liquid or solid fuels. Soot formation is a complex process involving the chemistry of fuel destruction under fuel-rich conditions where hundreds of aromatics and other intermediate ~5 compounds are formed (Figure 7.10~. An understanding of the mechanism of soot formation has become more important because soot hampers the use of such important technologies as staged combustion and diesel engines. In addition, the sooting tendency of aromatic compounds is higher than that of aliphatics, and the i: aromatic content of fuels is ex ~pected to increase in the future my> as petroleum resource availabil Fluoranthene ity forces refiners to use fuel feedstocks with lower ratios of hydrogen to carbon. Soot is objectionable not only because of its opacity but also because soot particles are car riers of toxic compounds. When combustion products cool, soot particles provide conden sation sites for hydrocarbon vapors, particularly PAHs. Soot particles are agglomerates of small, roughly spherical units. The small vary in di ameter from O.OOS to 0.2 ~m, with most in the range of 0.01 to 0.05 ~m, while the size and morphology of the clusters can range from aggregates of several particles to large contrails several micrometers in diameter and hundreds of micrometers in length. Soot particles are not pure carbon. The atomic ratio of hydrogen to carbon decreases from around 1.0 at the point H H H , ~ C C C C' :4 + C2H2(-H) ~+H(-H ~=. +C2H2 ~C_H ~3 _ it+ SOOT -+H(-H2) ~3 +C2H2(-H) it) +C2H2(-H) ~3 FIGURE 7.10 A possible mechanism for soot formation.

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_ if. / aqueous particles may participate in oxidation- reduction reactions with the particles, undergo chemical transformations in which the particle surface serves as a catalyst, or participate in heterogeneous photochemical processes. The design of effective engineering processes for the treatment of water supplies to remove toxic compounds by adsorption/reaction/particle-re- moval sequences demands fundamental data on the kinetics of the individual steps and the incorporation of the data into process models. A major challenge is to describe all relevant chemical influences on the efficiency of removal of specific toxic compounds. Among these are the physical and chemical properties of the absorbing particle surface, the alteration of these properties by reactions or dissolution- precipitation processes, and the stability of aqueous particles to coagulation. In contrast to the chemical conditions of conventional munic- ipal water and wastewater processing, the con- ditions selected or imposed by the special cir- cumstances for control of hazardous substances may include extremes of pH, redox potential, ionic content, and organic content. These fac- tors may become critical in the design of optimal processes combining adsorption, reaction, and coagulation steps. Recent development of the use of reversed micelles (aqueous surfactant aggregates in or- ganic solvents) to solubilize significant quan- tities of nonpolar materials within their polar cores can be exploited in the development of new concepts for the continuous selective con- centration and recovery of heavy metal ions from dilute aqueous streams. The ability of reversed micelle solutions to extract proteins and amino acids selectively from aqueous media has been recently demonstrated; the results indicate that strong electrostatic interactions are the primary basis for selectivity. The high charge-to-surface ratio of the valuable heavy metal ions suggests that they too should be extractable from dilute aqueous solutions. The potential of reversed micelles needs to be evaluated by theoretical analysis of the metal ion distribution within micelles, by evaluation of the free energy of the solvated ions in the reversed micelle organic solution and the bulk aqueous water, and by the experimental char acterization of reversed micelles by small-angle neutron and x-ray scattering. Wet Oxidation Incineration achieves high destruction effi- ciencies by fast free-radical reactions in the presence of water vapor at high temperatures (1,500-2,300C) and 1 atm. Waste can also be destroyed by oxidation at much lower temper- atures by operating at high pressures, including conditions above the critical point for water. For example, high destruction efficiencies (greater than 99.99 percent) of toxic organic compounds can be achieved in 2 seconds at moderate temperatures (1,000-1,200C) at 250 atm. The lower reaction temperature permits the destruc- tion of waste of much lower heating value than can be incinerated, at least without the use of auxiliary fuels. The chemistry of such reactions at high pressures and moderate temperatures needs to be further elucidated before wet oxi- dation processes can be more widely used in hazardous waste management. Remediation of Toxic Waste Sites Only two processes, high-temperature pyrol- ysis and mobile incineration, have proved ef- fective for soil decontamination and are consid- ered to be commercially viable. Both involve heating the contaminated soil to a high temper- ature, which is costly in terms of energy use and materials handling. There are substantial opportunities for innovation and development of processes for the separation of contaminants from soils and the in-situ treatment of contam- inated soils. Examples of each are given in the following subsections. Separation Processes One generic problem in site remediation is the removal or deactivation of small quantities of toxic organics from highly porous and sur- face-active media such as soil. Alternative pro- cesses to pyrolysis and high-temperature oxi- dation of soil, such as thermal Resorption, steam stripping, and supercritical extraction, require less energy and thus should be investigated

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further. Fundamental research on the nature of the adsorbed state of organics in soil could have as a significant payoff the identification of al- ternative process paths. Basic measurements of Resorption kinetics and pore diffusion in clas- sified fractions of soil components (e.g., clays, silts, and sand) can provide the basis for de- veloping accurate models of such processes as soil Resorption and migration of contaminated plumes. This information could be used to determine the conditions necessary for thermal Resorption and steam stripping. Extraction with supercritical fluids, such as carbon dioxide or methanol in carbon dioxide, offers the potential for combining the high mass- transfer coefficients of gases with the moder- ately high absorption capacities of liquid sol- vents. In addition, the solubility characteristics are highly sensitive to relatively small changes in temperature and pressure. Thus, the contam- inants can be recovered from the supercritical fluid after extraction and the supercritical fluid recycled at moderate cost. The method is being applied to tertiary oil recovery by the petroleum industry, a process somewhat akin to the re- moval of organics from soil. Fundamental re- search on the solubilities of organic compounds in supercritical fluids would expedite the eval- uation and application of this promising tech- nology. Biodegradation The use of biodegradation for the treatment of dilute waste streams has already been dis- cussed; it also has potential for in-situ treatment. The critical need is to learn how to select and control microorganisms in a soil environment to achieve the desired degradation of organics. Monitoring One of the most important elements in the remediation of existing waste sites is early detection and action. As an example, the cost of cleanup at Stringfellow, California, increased from an estimated $3.4 million to $65 million because of pollutant dispersal during a decade of inaction after the first identification of the problem. The opportunities for innovative sam ,~ ~ ~ ~ lo. pling strategies responsive to this need are discussed in the following section. BEHAVIOR OF EFFLUENTS IN THE ENVIRONMENT It has been recognized for some time that fluids in motion, such as the atmosphere or the ocean, disperse added materials. This property has been exploited by engineers in a variety of ways, such as the use of smoke stacks for boiler furnaces and ocean outfalls for the release of treated wastewaters. It is now known that dilution is seldom the solution to an environ- mental problem; the dispersed pollutants may accumulate to undesirable levels in certain niches in an ecosystem, be transformed by biological and photochemical processes to other pollut- ants, or have unanticipated health or ecological effects even at highly dilute concentrations. It is therefore necessary to understand the trans- port and transformation of chemicals in the natural environment and through the trophic chain culminating in man. The Atmospheric Environment Over the last two decades, significant progress has been made in understanding the mechanisms of transport and transformation of pollutants in the atmosphere. Mathematical models have been developed to describe the spatial and temporal distributions of sulfur dioxide, carbon monox- ide, nitrogen oxides, hydrocarbons, and ozone. These models now serve as the backbone for the development of state plans for implementing the 1977 Clean Air Act amendments. Region- wide air pollution and acid rain are current subjects of intensive mathematical modeling efforts. But in spite of the strides that have been taken, a number of important research problems remain in understanding the behavior of atmospheric contaminants. Organic compounds constitute about 25-30 percent of the fine aerosol mass (the mass contained in particles smaller than 2.5 Am di- ameter) in urban areas. They are of considerable interest because some of them, such as PAHs, are either suspected carcinogens or known mu- tagens. Still, little headway has been made

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126 toward engineering their systematic reduction in the atmosphere. The problem is complex because many dif- ferent sources contribute to atmospheric load- ings of organic compounds. Not only do toxic waste incinerators have to be considered, but so do more than 50 classes of mobile and stationary combustion sources and industrial processes that release small amounts of toxic organics mixed with other exhausts. In addition, reliable aerosol source samples of PAHs and their oxygenated or nitrated derivatives are difficult to collect because these compounds are present in both gas and aerosol phases. Special stack-sampling equipment must be designed to acquire meaningful samples. Emissions undergo transport and chemical transformation in the atmosphere. For example, mutagenic nitro com- pounds can be created by the reaction of PAHs with HNO3, NO', or NOOK. One way to analyze these atmospheric transformations is to com- pare the chemical composition of primary source effluents with that of ambient aerosol samples. However, source and ambient samplings now vary in methodology and analysis so that dif- ferences between them may be due to laboratory procedures. A comprehensive study, in which source and ambient measurements are made and analyzed the same ways, is needed. Source emission data could then be correlated with atmospheric transport calculations, and the rel- ative importance of source contributions to ambient organics could be identified. When spills and releases of hazardous gases or liquids occur, the concentration of the haz- ardous material in the vicinity of the release is often the greatest concern, since potential health effects on those nearby will be determined by the concentration of the substance at the time of the acute exposure. There are many models of routine continuous discharges (e.g., dis- charges arising from leaky valves in chemical plants), but these cannot be applied to single episodic events. Research on the ambient be- havior of short-term environmental releases and the development of models for concentration profiles in episodic releases are crucial if we are to plan appropriate safety and abatement mea- sures. Because most people spend the majority of FRO~N TIERS I.\' iCHEMICALL ENGIATEERI~`'G their time indoors, the quality of the indoor atmospheric environment is now receiving greater attention from researchers and regulators. There has been a reported increase in both the con- centration and diversity of pollutants in indoor environments; formaldehyde, nitrogen dioxide, carbon monoxide, and a diverse range of organic compounds have been identified. It is not certain whether this should be attributed to the use of new building materials and to changes in build- ing ventilation resulting from increased insula- tion or to the use of more sophisticated analyt- ical techniques. Since the principal indoor air pollutants are known or suspected to adversely affect health (Figure 7.16), there is a need to engineer systems that can reduce their genera- tion. Chemical engineers can assist in devel- oping such systems, including home heating and cooking burners that minimize the generation of oxides of nitrogen; ~ improved heat transfer devices that will allow for air exchange with the outside envi- ronment while avoiding excessive loss of heat; and ~ resins, binders, coatings, and glues for building materials that do not emit hazardous compounds, such as formaldehyde. Finally, there is a need for simple instrumen- tation that can be used to quantify occupant exposure to air pollution. The Aquatic and Soil Environments Disturbingly little is known about the mech- anisms of groundwater contamination, including not only those for transport and dispersion but also those for chemical transformation. Under- ground pollutant transport is often represented with rather simplistic plume models, in much the same way as traditionally done for the atmosphere. These models do not take into account the fact that, for the underground trans- port process alone, the detailed mechanisms of flow through inhomogeneous porous media rep- resent a major source of added complexity that cannot be ignored (Figure 7.171. Chemical en- gineering expertise in petroleum reservoir mod- eling can be applied to this area.

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ENVIRONMENT.4L PROTECTION, PROCESS SAFETY, HAZARDOUS WASTES :~ ~ NASAL CAVITY :~FORMALDEHYDE ~ /_ ~ -ORAL CAVITY TRACHEA ~ 1 ~ ~ _~IIT-~-~] DIOXIDE BRONCHUS i-\ L4 ~ ~ AMMONIA, SULFUR DIOXIDE \ ; ~PARTICLES UNDER3 N1 R O I ~ 1lN ~ ~_NllTR~rFKI nlm~lnF I I \\ I ~ f ~= - \ ~ ''''me '' 'a''' a\ _ ~ (FROM ALVEOLI INTO \ BLOODSTREAM) I ( ~ :~ CARBON DIOXIDE y / ~ t~w (FROM BLOODSTREAM PINTO ALVEOLI) ALVEOLI FIGURE 7.16 Health effects of indoor air pollution. Gaseous and particulate contaminants frequently found in indoor air pollution affect different parts of the respiratory system. Some, such as carbon monoxide and nitrogen dioxide, move from the lungs into the bloodstream. Models of chemical reactions of trace pollut- ants in groundwater must be based on experi- mental analysis of the kinetics of possible pol- lutant interactions with earth materials, much the same as smog chamber studies considered atmospheric photochemistry. Fundamental re- search could determine the surface chemistry of soil components and processes such as ad- sorption and Resorption, pore diffusion, and biodegradation of contaminants. Hydrodynamic pollutant transport models should be upgraded to take into account chemical reactions at sur- faces. Considerable work has been done on the behavior of pollutant species at air-water and air-soil interfaces. For example, wet and dry deposition measurements of various gaseous and particulate species have been made over a wide range of atmospheric and land-cover con- ditions. Still, the problem is of such complexity that species-dependent and particle-size-de- pendent rates of transfer from the atmosphere to water and soil surfaces are not completely understood. There is much to be learned about pollutant transfer at water-soil interfaces. Con- cern about groundwater contamination by min

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~8 . \',Compilance point Aqulfer \ Flow I\__ 1 1~ b:-------:-:-:-:-:-:-::::-~-------: ~.~.................. . _ .. . Waste ~ ~ B constituent ~ I;;;; source | ~ -K ~ Aqulfer I.. ::::::::::::: Plume of contaminants Sampilng wells, downgradlent Upgradlent well eral processing leachates, by rainwater leaching of landfills, and by runoff of contaminated surface water has heightened the opportunities for further work in this area. Ambient Monitoring Advances in understanding the transport and fate of chemicals in the environment will depend on substantial improvements in measurement capabilities. Attention should be directed to- ward instrumental techniques that can deter- mine the oxidation state of inorganic species, which often has a marked influence on reactiv- ity, transport properties, and toxicity of the ion. Free radicals and other highly reactive trace species play important roles in the chemistry of the environment. Detection of these species FRONTIERS IN CHEMICA.L E.\G1NEERING it, 1 if Acted fracture Waste constituent l source Ground water flow l ~ 1 Compilance olnt FIGURE 7.17 Oversimplified and more realistic views of plume migration in underground water. Plume migration is affected by inhomogeneities in the aquifer. The diagram on the right shows that gravitational influences or fractures on the aquifer might cause plumes to flow in directions different from the direction of groundwater flow. Courtesy, Office of Technology Assessment. requires rugged and reliable instrumentation that can be transported and used in the field. Remote sensing technology should be explored as a means of characterizing regional pollutant distributions. The extent of groundwater contamination from landfills and storage tank leakage is often unknown (Figure 7.181. It is important to devise measurement strategies to characterize the spa- tial, chemical, and temporal nature of this prob- lem. Chemical engineers have been at the fore- front in using advanced mathematical tools and instrumentation to characterize the size and extent of petroleum reservoirs. This technology should be transferred to the groundwater prob- lem and, in particular, to the task of designing cost-effective sampling strategies. Other options include probing potential subsurface sources of

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ENVIRONMENTAL PROTECTION, PROCESS SAFETY, 0.47,4~6TS WASTES - 1' 1 2 e "" ~ ~ ~ ~storage\, <~.~!~( 4~ ~: ~ ~ ~ -it Con am'na ng l;; ~ ~ ' ... Soil Contaminated ~ ' ' ' 22', By Residual Gasoline ................................... , , it. ~ ., ,.,.,.,. A.,., , ,., . ,. ~. .................. ' 2,'. Accumulated'. ~ : FIGURE 7.18 Leakage from underground storage tanks. Some 2 million underground steel storage tanks are buried beneath service stations throughout the country. Another 1.5 million steel gasoline tanks are buried on farms. Thousands of "orphan" tanks are believed to have been left behind when service stations were razed for redevelopment. Leaks from these tanks could allow hazardous organic compounds to migrate beneath the surface, polluting soil and aquifers and releasing fumes to the surface. Courtesy, E.I. du Font de Nemours and Company, Inc. pollutants by nondestructive methods such as acoustic probing, eddy current techniques to assess tank corrosion, magnetometers for lo- cation of buried drums, and electrical resistivity measurements. Improvements in the monitoring and opera- tion of incinerators could minimize the acciden- tal release of hazardous effluents. In particular, fast-acting, continuous, on-line monitors are needed to detect excursions in operating con- ditions that could lead to toxic emissions. Development of methodologies for charac- terizing and measuring human exposure to chemicals is a challenging scientific and engi- neering undertaking. Data are needed for studies of risk assessment and health effects. During the past decade, rudimentary monitors have become available to determine a person's ex- posure by measuring concentrations of a given pollutant in the air breathed. Efforts should be directed to lowering the cost and increasing the sensitivity, chemical selectivity, and accuracy of these monitors. Widespread use of personal exposure monitors offers the potential for im- proving epidemiological studies and for devel- oping a more rigorous scientific basis for setting standards in the workplace and the general environment. 129 Multimedia Approach to Integrated Chemical Management _ - . '| ll'Current laws and programs fo 1111lllIlllllcus on the removal of pollutants from the medium-air, water, or land in which they are found, often with little regard for chem ical management of the environ ment as a whole. Because mod ern analytical techniques have revealed trace amounts of many toxic chemicals throughout the environment, however, the me dium-specific approach to pol lution control is now questiona ble.15 The diverse effects of acid rain and of leachates from haz ardous waste sites illustrate the mobility of chemicals in the en vironment ([Figure 7.19~. The following list gives many areas of research opportunity in a multimedia ap proach to chemical management of the environ ment: ~ characterization of background levels of chemicals and geochemical cycles; basic kinetic studies of chemical degrada- tion; field experiments to measure pollutant fluxes among media; fundamental studies of interracial dynam- ~cs; better determination of Henry's Law con- stants for volatile species; study of chemical speciation, including binding of organic compounds in soil and surface waters (Figure 7.201; studies of sorption and Resorption of heavy metals on suspended organic matter; and formation of precipitates in response to changes in pH. ASSESSMENT AND MANAGEMENT OF HEALTH, SAFETY, AND ENVIRONMENTAL RISKS Two of the biggest challenges facing chemical engineering in the near future are (1) the iden 1

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HERS IN CHEA8~CAL ENGEtYE~.~\G Prevailina Winds _ , , . ~ 1, . ., ;, by ., __c5 ~ ~\ Photochemistrv Mu merit ~::~r~Pc tification and evaluation of the risks- both real and perceived to human health and to the environment from exposure to chemicals (risk assessment) and (2) the adequate control of these risks (risk management). The ultimate objective in meeting these challenges is to en- sure that risks in the chemical and processing industries are viewed as acceptable by the public, regulatory bodies, and the courts, while maintaining worldwide technological leadership and cost competitiveness in these industries by capitalizing fully on advances in chem- istry, biotechnology, materials, and microelec- tronics. These challenges are critical to the profession of chemical engineering, the chemical industry, and our country. Risk assessment and manage- ment involve input from a multitude of differ- ent disciplines. The methodology is rapidly changing and extremely complex and requires both technical input and input from profes- sionals with expertise in legal, economic, judi- cial, medical, regulatory, and public perception issues. ~: *,,.\. , ~. ,,.~ Aauatic Ecosvstem FIGURE 7.19 Mobility of acid rain a multimedia problem. Reprinted from Opportunities in Chemistry. National Academy Press, 1985. Risk Assessment Risk assessment, an obvious precursor to risk management, first identifies a hazard and then quantifies the likelihood of occurrence (hazard assessment) and the impact (exposure assess- ment) associated with each hazard event. Hazard Identification arid Assessment Two main hazards associated with chemicals are toxicity and flammability. Toxicity mea- surements in model species and their interpre- tation are largely the province of life scientists. Chemical engineers can provide assistance in helping life scientists extrapolate their results in the assessment of chemical hazards. Chemical engineers have the theoretical tools to make important contributions to modeling the trans- port and transformation of chemical species in the body from the entry of species into the body to their action at the ultimate site where they exert their toxic effect. Chemical engineers are also more likely than life scientists to ap

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~NV^'RO.~-TAL PR0~' I0,A~, ~63~SS Satisfy preciate realistic conditions and exposure scen- arios for the use of hazardous chemicals in industrial settings. Their assistance in interdis- ciplinary efforts is needed to relate toxicity measurements to actual practice. Identification of hazards of unexpected, epi- sodic events such as transportation accidents, equipment failure, fires, and explosions is largely the responsibility of the chemical engineer. The most difficult problem in the quantification of toxicity, explosion, and fire hazards of unex- pected and episodic natures is the estimation of the probability of occurrence. Risk analysts draw on both analysis and experience to gen- erate sequences of component and subsystem failures that might lead to significant accidents. Methods such as fault-tree analysis can be used to display failure sequences in a logical format. Mechanical failures, operator errors, and man- agement system deficiencies must all be consid- ered in identifying and quantifying risks. Risk assessment for complex systems involv- ing hazardous chemicals requires deep under IS WASTES )37 standing of the full spectrum of operations. It is highly interdisciplinary and potentially re- quires manipulation of massive amounts of in- formation, some of which may be missing or of uncertain validity. While the techniques and governing rules for risk assessment are generally straightforward, much creative work needs to be done before the methodology can be used efficiently and effectively to anticipate and cor- rect safety problems or to analyze operating abnormalities for precursors of danger. New techniques employing expert systems for analysis of complex chemical processes can be used to anticipate safety problems associated with various design decisions. In many major accidents, the relevant fundamental phenomena involved were totally unanticipated and were understood only after considerable investiga- tion. Some of these abnormal conditions might have been identified by a priori research guided by techniques for anticipating interactions that might be overlooked in conventional approaches to design. Other serious accidents were pre F1GURE 7.20 The binding properties of chemicals can affect their distribution and retention in various environmental media. For example, the hypothetical environmental fates of two chemicals are contrasted. The profile on the left shows the loading in various media over time for a chemical that binds strongly with lipid material. The profile on the right shows the loading in various media over time for a chemical that binds strongly with organic material. Courtesy, Office of Technology Assessment. Water

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ceded by abnormalities in operation that were ignored until it was too late. Again, techniques for identifying and investigating such warning signals might have avoided disaster. Exposure Assessment There is a dearth of information and meth- odology in the area of human and environmental exposure assessment. Standardized methodol- ogies have not been developed; monitoring of personnel exposure is rare; and suitably sensi- tive, rapid-response, portable analytical equip- ment is limited. Fortunately, the exposure factor is a controllable variable, at least theoretically, and is largely within the province of the chemical engineer, who selects and designs processes, sites and expands plants, and develops plant operating procedures and transport systems. To determine the likely dispersion of flammable materials, as well as the transport of toxic chemicals in the environment, dispersion/reac- tion models (both near field and far field) for realistic accident scenarios (e.g., heavy gases, dusts, aerosols) must be developed and verified experimentally. Risk Management Once the hazard and exposure assessments are complete for any specific hazard, it is relatively simple to determine how many people will be affected and the severity of the effect (i.e., the risk). It is considerably more difficult to decide whether these risks are warranted compared to the benefits. This is particularly true if the risks are uncertain, involuntary, or not understood by those at risk; if those at risk are not primarily those who benefit; or if alter- natives are unknown, uncertain, or impractical. The process is complex because the goals are multiple and frequently contraindicating. Economic, liability, public image, and opinion considerations are involved. Catastrophic haz- ards are less acceptable than smaller ones even if the absolute risk is identical. Voluntary risks are a way of life for most people, but there is minimal tolerance for involuntary risks, partic- ularly if they are unknown or not understood. In today's heavily regulated and litigious society, it is becoming increasingly essential that risk assessments be conducted and ade- quately and carefully documented for all existing industrial plants and transport systems that handle or store significant quantities of toxic or flammable chemicals. The same must be done in siting new facilities, selecting processes, designing processes and equipment, developing operating and maintenance procedures, and de- signing transport systems. Policies and procedures for risk management decisions must be established and be clear and simple if the massive, but necessary, workload of risk assessment and management is not to cripple the chemical industry's worldwide com- petitive position and consume inordinate re- sources through inefficiency. Managing chemical risk must proceed in the absence of perfect information on risks and how to avoid them. The lack of critical information or good alternatives is no excuse for inaction. IMPLICATIONS OF RESEARCH FRONTIERS This chapter has made clear the challenges to chemical engineers in research related to environmental protection, process safety, and hazardous waste management. Chemical engi- neering education must become strongly ori- ented to these topics, as well. For example, what might be characterized as the traditional approach to environmental concerns in process design- establishing the process and then pro- viding the necessary safety and environmental controls must give way to a new approach that considers at the earliest stages of design such factors as process resilience to changes in inputs, ~ minimization of toxic intermediates and products, and ~ safe response to upset conditions, startup, and shutdown. As chemical engineering research develops new design and control tools to deal with these factors, these tools should be integrated into the curriculum. Process safety research is gen- erally more advanced in industry than it is in

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academia. Closer interaction between industrial researchers and academic researchers and ed- ucators is needed to disseminate insights and knowledge gained by industry in this area. Other problems in environmental science and technology as well as an introduction to the social, economic, and political aspects of en- vironmental issues should receive broad ex- posure in the curriculum. They should be in the content of existing courses wherever possible. Industry has strong developmental research programs in areas such as process safety, but more fundamental research on process design tools, on emerging environmental problems, or on general topics linked to public health and environmental protection requires stable, long- term research support from the federal govern- ment. The chemical engineering profession stands ready to tackle these issues aggressively; does the federal government? The principal federal agencies that have sup- ported environmental research generally have been the Environmental Protection Agency, the National Science Foundation, the National Oceanic and Atmospheric Administration, the National Institute of Environmental Health Sci- ences, and the Department of Energy. In recent years, many of these agencies have experienced budget cuts that threaten their ability to maintain vital research programs that anticipate environ- mental problems, instead of reacting to the latest crisis. Cutting back on basic research on envi- ronmental problems is a false economy. Small savings today on anticipatory research may result in very large costs to society in the future, since dealing with the consequences of envi- ronmental problems is invariably more expen- sive than research to anticipate and prevent these problems. Because of the critical importance of main- taining our environmental quality and improving process safety and hazardous waste manage- ment, the committee recommends that these federal agencies undertake new initiatives in chemical engineering research. The details of proposed initiatives for EPA and NSF are spelled out in more detail in Chapter 10 and Appendix A of this report. An investment in research to anticipate and prevent environmental problems is likely to be highly cost-effective. The costs of responding to unforeseen environmental problems have certainly been great. Signifi- cantly increased support for fundamental re- search is vital if universities are to preserve their role in long-term environmental research and in the education of tomorrow's researchers, process designers, and regulators. NOTES 1. J. L. Makris. Natural Hazards Observer, 10~3), January 1986, 1. 2. J. McLoughlin. "Risk and Legal Liability" in Dealing with Risk, R. F. Griffiths, ed. New York: John Wiley & Sons, 1982. 3. National Safety Council. Accident Facts. Chi- cago: National Safety Council, 1985. 4. U.S. Department of Commerce, Bureau of the Census. Statistical Abstract of the United States: 1987, 107th ed. Washington, D.C.: U.S. Govern- ment Printing Office, 1986, Table 697. 5. One Hundred Largest Losses-A Thirty- Year Review of Property Damage Losses in the Hy- drocarbon-Chemical Industries (OHL-9-86-71. Chicago: Marsh and McLennan, 1986. 6. McGraw-Hill Economics. Survey of Investment in Employee Safety and Health, 13th ed. New York: McGraw-Hill, 1985. 7. James L. Regens, "The Regulatory Environment for Coal Development," in Costs of Coal Pol- lution Abatement: Results of an International Symposium. Paris: Organisation for Economic Cooperation and Development, 1983. 8. The National Survey of Hazardous Waste Gen- erators and Treatment, Storage, and Disposal Facilities Regulated Under RCRA in 1981. WESTAC, Inc., 1984. 9. U. S. Congress, Congressional Budget Of lice. Hazardous Waste Management: Recent Changes and Policy Alternatives. Washington, D.C.: Congressional Budget Office, May 1985. 10. U.S. Congress, Committee on Public Works and Transportation, Subcommittee on Investigations and Oversight. Hazardous Waste Contamination of Water Resources (Concerning Groundwater Contamination in Santa Clara Valley, CA) (99- 321. Washington, D.C.: U.S. Government Print- ing Office. 11. U.S. Congress, Office of Technology Assess- ment. Superfund Strategy (OTA-ITE-2521. Washington, D.C.: U.S. Government Printing Office, 1985.

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734 12. T. A. Kletz. Simpler, Cheaper Plants or Wealth and Safety at Work Notes on Inherently Safer and Simpler Plants. London: Institution of Chemical Engineers, 1984. 13. U.S. Environmental Protection Agency, Science Advisory Board. Incineration of Hazardous Liq- uid Waste. Washington, D.C.: U.S. Environ- mental Protection Agency, 1984. FF ON IFS ER ~ IN IDEA ~ ~ ^~iA\E~^ ^\ ~ 14. U.S. Congress, Office of Technology Assess- ment. Technologies for Hazardous Waste Man- agement. Washington, D.C.: U.S. Government Printing Office, 1981. 15. For a detailed discussion of this topic, see Y. Cohen, ed. Pollutants in a Multimedia Environ- ment. New York: Plenum Press, 1986.