(.3.... 5 1111113._c_u_r_r_i_c_u_l_u_m______)

HAZARDOUS WASTE PROCESSING In the Chemical Engineering Curriculum

DIANNE DORLAND, DoRAB N. BARIA University of Minnesota, Duluth • Duluth, MN 55812

s our nation's tolerance for pollution in general has decreased, the use of chemical engineering skills in Dianne Dorland is Associate Professor of chemi­ waste management has steadily increased. This is cal engineering at University of Minnesota, Duluth. A She received her BS and MS from the South Da­ particularly true where pollution prevention at the source has kota School of Mines and Technology and her PhD been emphasized over "end of the pipe" treatment. Second­ from the West Virginia University (1985). She cur­ rently teaches the Hazardous Waste Processing ary wastewater treatment will continue to be the principal Engineering course sequence for chemical engi­ public health shield for our sewer discharges, but tertiary neers, and her research interests include industrial wastewater treatment is frequently mandated for an indus­ wastewater treatment and hazardous waste man­ agement. trial facility and is becoming more common for wastewater treatment in publicly owned treatment works (POTWs). Dorab N. Baria is Professor of chemical engi­ neering at the University of Minnesota, Duluth. He Wastewater treatment, or sanitary engineering, has tradi­ received his PhD in chemical engineering from tionally been part of civil engineering, and more recently of Northwestem Universtiy in 1971. He subsequently worked for the U.S. Atomic Energy Commission the relatively new field of environmental engineering. Sani­ at the Ames Laboratory, Iowa State University, as tary engineers have satisfactorily designed and operated a research fellow for fifteen months and then was a chemical engineering faculty member at the wastewater and sewage treatment plants without ever having University of North Dakota until 1985, when he taken courses in chemical kinetics and reactor design, chemi­ joined the UMD faculty. cal thermodynamics, or unit operations. Most of these plants were, basically, primary treatment facilities, with some of them including secondary treatment. The fact that most of All this activity has given rise to the field of environmental the facilities did not face major problems was because sani­ engineering, which is now replacing sanitary engineering in tary engineers had acquired, and could draw on, a large body many civil engineering programs. According to the state­ of empirical information on wastewater treatment and plant ment of purpose published by the Environmental Engineer­ operation. Efficient operation and the use of advanced or ing Division of the American Society of Civil Engineers,[ll tertiary wastewater treatment were not prime considerations. environmental engineering deals with solutions of problems of environmental sanitation, notably the provision of safe, Due to the growing consciousness of hazardous wastes palatable, and ample public water supplies; proper disposal and incidents such as Love Canal and Times Beach, the or recycling of wastewater and solid wastes; adequate drain­ public has .demanded that federal, state, and local govern­ age of urban and rural areas for proper sanitation; control of ments get involved in the control and management of haz­ atmospheric, water, and soil pollution; and the social and ardous substances and wastes. This demand has led to for­ environmental impacts of these solutions. It is also con­ mation of the Environmental Protection Agency (EPA) as cerned with engineering problems in the field of public well as the Clean Air Acts, the Clean Water Acts, the health, such as control of arthropod-borne diseases, elimina­ Toxic Substances Control Act, the Resource Conservation tion of industrial health hazards, provision of adequate sani­ and Recovery Act (RCRA), the Comprehensive Environ­ tation in urban, rural, and recreational areas, and the effect of mental Response, Compensation, and Liability Act technological advances on the environment. (CERCLA), and the Superfund Amendments and Reauthori­ zation Act (SARA). The above areas that come under the working umbrella of chemical engineering include the proper disposal or recy- © Copyright ChE Division of ASEE 1995 178 Chemical Engineering Education cling of wastewater and solid wastes, and the control of including a final , and homework counts twenty-five percent. atmospheric, water, and soil pollution. A common method The remaining twenty-five percent of the grade is for a of disposal is incineration. Design and operation of efficient written report on an engineering design of a system handling incinerators that meet federal standards require a knowledge hazardous wastes, individually produced by each student. of chemical thermodynamics, kinetics, and stoichiometry, Several texts and references have been used for this course, while control of pollution uses the principles including Davis and Cornwell,(1 1 Allen, learned in mass transfer operations, filtra- et al.Y 1 Dawson and Mercer,131 4 tion, sedimentation, chemical reactions, Eckenfelder, C l Peavy, Rowe, and chemical thermodynamics, and kinetics and Because of the Tchobanoglous,CS1 Tavlarides ,c61 Wark and reactor design. A thorough knowledge of strong influences Warner,l71 and Wentz_csi Because of the broad organic chemistry and stoichiometry is re­ subject area, no one text has proven entirely quired for solving most problems dealing of transport phe- satisfactory, and a large component of the with environmental engineering. nomena and eco- teaching material is excerpted from recent . . . Hazardous substances and wastes, as de­ nomics in air journals such as Chemical Engineering, En­ fined by various federal and state statutes, vironmental Engineering, Waste Manage­ are produced by most chemical industries. pollution preven­ ment, Environmental Progress, Combustion In many instances they can be modified into tion and control, Science Technology, and Chemical Engi­ nonhazardous substances, or destroyed by the chemical engi­ neering Progress. Materials dealing with chemical means, but newer methods of pol­ state regulations, available from the Minne­ lution control and safe disposal of wastes neer is singularly sota Pollution Control Agency, are also fre­ must be developed; more importantly, newer equipped to design quently used. Course content is continually processing methods that will not produce developing in response to current legisla­ hazardous wastes need to be developed. In and implement air tion and technological progress. order to do this, a thorough understanding pollution control Protecting and improving the environment of the thermodynamics and kinetics of systems. are now recognized imperatives for sound chemical processes is needed. Chemical en­ management. Chemical engineers will face gineers are best equipped to design and op- important challenges in the future: design­ erate equipment or systems for the proper disposal and recy­ ing inherently safer and less polluting plants and processes, cling of wastewater and solid wastes and to make process improving air and water quality, and managing hazardous modifications to avoid production of hazardous wastes. wastes responsibly. These challenges have important impli­ It was with these insights that the chemical engineering cations for chemical engineering education, which is the program at the University of Minnesota, Duluth (UMD) reason this course was developed. decided to include in its ABET-accredited curriculum a se­ quence of two courses that deal with processing of hazard­ COURSE CONTENT ous wastes. Increasing numbers of our graduates are now The first topic covered is the definition of pollution, gener­ finding places as chemical engineers with environmental or ating lively discussion as the legislative, industrial, personal, waste management responsibilities. and aesthetic viewpoints are presented. Throughout the course, an attempt is made to maintain this parallel perspec­ COURSE STRUCTURE tive of what is ethical and what is defined by law. Presenting Hazardous Waste Processing Engineering I-II is a sequence the history of federal regulations and the current status of of two 4-credit courses taught in the winter and spring quar­ key legislation leads into the global issues of acid rain, ters of the junior year. The class meets thirty times a quarter greenhouse effect, and ozone depletion problems. for sixty-five minutes per lecture. Prerequisites include a The next major topic is air pollution, starting with a defini­ year of organic chemistry and a year of engineering physics, tion of air pollutants, their origins and effects, and the differ­ with physical chemistry as a corequisite. Chemical engineer­ ence between primary and secondary air pollutants. Meteo­ ing majors have also completed stoichiometry and fluid me­ rological effects, particularly atmospheric stability and plume chanics, and concurrently take mass transfer, chemical ther­ behavior, are reviewed before introducing basic concepts of modynamics, and kinetics (in physical chemistry). dispersion modeling. EPA-approved dispersion models are The overall goals of the courses are to identify hazardous downloaded from the Internet and used by the students. substances and their effects, study federal and state regula­ While models of varying levels of complexity are available tions, design waste treatment processes to meet effluent from this source, the easiest EPA model to use is the standards, and to understand the management of hazardous SCREEN2 model. When possible, real data from local in­ wastes. Fifty percent of the grade is based on examinations, dustries are used to study dispersion of pollutants. This Summer 1995 179 includes the Toxic Release Inventory (TRI) information avail­ Engineering ethics and the responsibility of the engineer able on CD-ROM in the University library. to the public are frequent discussion topics as regulations such as SARA, RCRA, CERCLA, and the Clean Water and This leads into particulate, SO2, and NO, control. The basic design of various particulate control equipment for Clean Air Acts and their amendments are presented. Materi­ handling the 200-micron to sub-micron particles is studied. als such as the video Gilbane Gold, developed by the Na­ These include a settling chamber, cyclone, venturi scrubber, tional Institute for Engineering Ethics of the National Soci­ electrostatic precipitator, and bag house filter. A range of ety of Professional Engineers, are used to reinforce the twin wet and dry desulfurization processes is considered, from responsibilities of personal and professional ethics and first-generation processes using lime/limestone slurry scrub­ pollution prevention. Gilbane Gold also deals with the re­ bing to second-generation processes such as alkali scrub­ sponsibilities of the engineer to his or her employer and bing, dry adsorption, catalytic oxidation, and dilute sulfuric the public, and with the question of whistle-blowing and acid scrubbing (Chiyoda) processes, and future-generation its consequences. processes such as the Bureau of Mines citrate process. The Many methods are used for the control, alleviation, or difficulty of meeting NO, standards through modifications removal of hazardous waste. These include physical, chemi­ in operating conditions leads to the discussion of modifica­ cal, and biological processes, and they present many oppor­ tions of burner design and the development of novel fur­ tunities for the chemical engineer. This is especially obvious naces to meet the standards. in hazardous waste applications such as incineration, gas Removal of NO, after its formation from flue gases by absorption, and solvent extraction. The question of ultimate catalytic and non-catalytic decomposition, reduction, absorp­ disposal is posed for discussion, recognizing that many pol­ tion, or membrane separation processes completes this sec­ lution control processes produce other process residuals. tion of the course. If time or opportunity permits, subjects Land disposal is a frequently chosen option, and the design such as photochemical reactions, smog formation, and hy­ and operation of landfills is considered, along with other drocarbon removal may be presented. The ·influence of eco­ disposal options such as deep-well injection. nomics on the choice of pollution control processes is also At this point it is easy to reemphasize the philosophy that an important concept that must be recognized by the stu­ the best method of pollution control is to change the process dents. Because of the strong influences of transport phenom­ to decrease or eliminate the initial waste production. ena and economics in air pollution prevention and control, Examples of eliminating the formation of hazardous sub­ the chemical engineer is singularly equipped to design and stances by use of selective catalysts or change in process implement air pollution control systems. conditions, such as temperature and pressure, are pre­ Water and wastewater treatment are discussed next. Physi­ sented. All these methods are tailor-made for application cal, chemical, and biological water-quality parameters are by chemical engineers. defined, with emphasis on their origin, impacts, and mea­ Case studies are frequently used to provide examples of surement. Purification to drinking water standards leads the waste generation, pollution control, and ultimate disposal, class to wastewater treatment. The basic design of various and examples such as Love Canal are used to present some water treatment processes and equipment, including coagu­ of the more spectacular failures and their consequences. lation, mixing, flocculation, sedimentation, filtration, and Local, regional, national, and global current events continu­ disinfection, is studied. The settling and filtration of primary ally provide the class with abundant examples for discus­ treatment, aerobic and anaerobic reaction systems in second­ sion. Students are encouraged to bring news articles of inter­ ary treatment, and advanced technology used in tertiary treat­ est to class, and approximately ten minutes of daily class ment, are presented in terms of the unit operations and unit time is devoted to exchanging ideas on current problems and processes that chemical engineers design and operate in all how they fit into the course material. The class has a dedi­ areas of the chemical industries. Discussion of advanced cated bulletin board for posting these articles that generates technology in tertiary treatment includes mass transfer, bio­ a great deal of public interest and is frequently read by logical and chemical oxidation, adsorption, ion exchange, casual passersby. This forum becomes a vehicle for develop­ and membrane processes. ing the student's ethical attitudes and philosophy in conjunc­ The definition of hazardous wastes and waste manage­ tion with a technical education. ment terminology are presented next. Designation of hazard­ Individual design problems are also assigned during the ous wastes by the listing and the criteria methods is two quarters, one for a liquid waste stream and another discussed, identifying the hazardous parameters of con­ for gaseous waste. The student is free to look at eco­ cern and their threshold values. Alternate methods of han­ nomic recovery, novel removal technology, or conventional dling wastes, such as waste reduction, waste separation disposal techniques, but must design a system that will and concentration, waste exchange, and energy/material re­ meet all federal standards for the wastes in question. The covery, are examined. final design report must present the problem, discuss the 180 Chemical Engineering Education options considered, and present the solution chosen, with main. It is an area vital to the long-term health and growth of supporting calculations. Good writing skills are required the chemical engineering profession, both from an industrial not only in the formal report, but also throughout the course. and personal viewpoint. Chemical engineers are best equipped The design problem counts for twenty-five percent of the with the knowledge for designing and operating equipment grade in that quarter. or systems for the proper disposal and recycling of waste This course is exciting and dynamic With the interaction water and solid wastes, for proper pollution control, and for between coursework and current events, there is always an process modifications to avoid production of hazardous ma­ abundance of material for consideration. For example, a terials. This educational program will meet future needs for June 1992 railroad accident in Superior, Wisconsin, resulted maintaining and improving the environment. in a mixture of chemicals, including benzene, being spilled REFERENCES both on land and in the Nemadji River. The resulting cloud caused the evacuation of thousands of residents, the largest 1. Davis, M.L., and D.A. Cornwell, Introduction to Environ­ mental Engineering, 2nd ed., McGraw-Hill, New York, page evacuation to date in the U.S. due to a spill of hazardous 4 (1991) materials. Resources from the regulatory agencies in Wis­ 2. Allen, D.T., N. Bakshani, and KS. Rosselot, Homework & consin and Minnesota are available to present this local case Design Problems for Engineering Curricula, AIChE, AIPP study in class, and discussion touches on the areas of spill & CWRT (1992) 3. Dawson, G.W., and B.W. Mercer, Hazardous Waste Man­ response, hazard assessment, reporting, cleanup, and panic. agement, Wiley-Interscience, New York, NY (1986) 4. Eckenfelder, Jr., W.W., Industrial Water Pollution Control, SUMMARY 2nd ed., McGraw-Hill, New York, NY (1989) 5. Peavy, H.S., D.R. Rowe, and G. Tchobanoglous, Environ­ Hazardous waste management is a relevant area for chemi­ mental Engineering, McGraw-Hill, New York, NY (1985) cal engineering skills that are not in the realm of civil engi­ 6. Tavlarides, L., Process Modifications for Industrial Pollu­ neering, and it is vital that chemical engineers have a firm tion Reduction, Lewis Publishers, Chelsea, MI (1985) 7. Wark, K, and C.F. Warner, Air Pollution: Its Origin and foundation in pollution prevention. The capability to de­ Control, 2nd ed., Harper and Row, New York, NY (1981) velop and change process structure places responsibility for 8. Wentz, C.A. , Hazardous Waste Management, McGraw-Hill, waste management firmly in the chemical engineer's do- New York, NY (1989) 0

POWDER TECHNOLOGY COURSE Continued from page 177

The Mikro-Pul Hosokawa Company's Micron Powder­ 2. Rumpf, H., "Mechanical Process Engineering as a Branch of Characteristics-Tester is a measuring instrument that is com­ Science Within the Scope of University Education," Eng. mercially available and is used for demonstration. A sche­ and Sci., Third Annual Number (1962) 3. Ford, L.J., "The Specially Promoted Program (SPP) in Par­ matic representation of the apparatus and a list of all mea­ ticulate Technology," Powder Tech., 65, 1 (1991) surements that can be performed with it are given in Figure 4. Ennis, B.J., J. Green, and R. Davies, "Particle Technology: 1. The students can measure the angle of repose (the angle The Legacy of Neglect in the U.S.," Chem. Eng. Prag., p. 32, which a heap of powder makes with the horizontal), April (1994) flowability (capacity of a powder to flow out from a vertical 5. Tilton, J.N., "Fluid Mechanics in Chemical Engineering Edu­ cylindrical vessel with a hole in the bottom), and dispersability cation: The Costly Omission ofMultiphase Flow," J. ofFluid/ Part. Sep., 2 (1989) of a powder in air (talc and sand in this case) and compare it 6. Chase, G., "Closing the Education Gap in Fluid-Particle to the behavior of a liquid. The demonstration module is Processes," J. of Fluid-Part. Sep., 6(1), 1 (1993) being introduced into a general engineering course given to 7. Dallavelle, J.M., Micromeritics: The Technology ofFine Par­ all engineering students in the first semester of study. ticles, Pitman Publishing, New York, NY (1943) 8. Orr, C., Particulate Technology, Macmillan Co., New York, ACKNOWLEDGMENT NY (1966) This work was supported by NSF Grant #CTS-9224463. 9. Beddow, J.K, Particulate Science and Technology, Chemi­ cal Publishing Company, New York, NY (1981) Support of the program by Mr. Charles F. Irwin from Unilever 10. Kendall, K, KL. Johnson, and A.D. Roberts, Proc. Roy. Research U.S. Inc., Dr. Reg Davis from DuPont, and Dr. M. Soc., A324, p. 301 (1971) Roco from NSF is greatly appreciated. 11. Briscoe, B.J., and M.J. Adams (eds.), Tribology in Particu­ late Technology, Adam Hilger, Bristol and Philadelphia, PA REFERENCES (1987) 1. Rietema, K , The Dynamics of Fine Powders, Elsevier, Lon­ 12. Bird, R.B. , W.E. Stewart, and E.N. Lightfoot, Transport don and New York (1991) Phenomena, John Wiley & Sons, New York, NY (1960) 0 Summer 1995 181