Environmental Restoration and Separation Science - ACS Symposium

Chapter 1

Environmental Restoration and Separation Science 1

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D. T. Reed , I. R. Tasker , J . C. Cunnane , and G. F. Vandegrift

1Chemical Technology Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 National Institute for Petroleum and Energy Research, IIΤ Research Institute, P.O. Box 2128, Bartlesville, OK 74005 Downloaded by 80.82.77.83 on March 22, 2017 | http://pubs.acs.org Publication Date: October 27, 1992 | doi: 10.1021/bk-1992-0509.ch001

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The problem of environmental restoration, s p e c i f i c a l l y the cleanup of contaminated s o i l s and groundwaters, i s one of the most important technical and s o c i e t a l problems we face today. To provide a background to t h i s problem, the extent and cost, laws and regulations, important contami nants, and key issues i n environmental restoration are discussed. A b r i e f introduction to the role of separation science, i n r e l a t i o n to environmental restoration, i s also given.

The cleanup of anthropogenic contaminants that are present i n the environment i s one of the most important problems that we face today. These contaminants can cause a wide range of p o l l u t i o n problems, including global climate change, ozone depletion, e c o l o g i c a l deterioration, and groundwater contamination. The remediation of existing waste, along with concerns over the fate of waste we are currently generating or plan to generate, i s recognized by the public as the leading environmental issue of today (1,2). The applications of separation science to environmental restoration are centered on the cleanup of contaminated groundwaters and s o i l s . The extent and complexity of the groundwater contamination problem continues to present formidable technological obstacles to cleanup. The most important factors that contribute to t h i s complexity are the large number of contaminated s i t e s , the wide d i v e r s i t y of the contaminants present i n those s i t e s , the inherent complexity of the subsurface chemistry of the contaminants, and the d i f f i c u l t y i n interpreting e x i s t i n g regulations to e s t a b l i s h compliance and properly p r i o r i t i z e s i t e remediation e f f o r t s . Separation science has already had an important role i n the cleanup of contaminated groundwater and s o i l . I t has been

0097-6156/92/0509-0001$06.00A) © 1992 American Chemical Society

Vandegrift et al.; Environmental Remediation ACS Symposium Series; American Chemical Society: Washington, DC, 1992.

Downloaded by 80.82.77.83 on March 22, 2017 | http://pubs.acs.org Publication Date: October 27, 1992 | doi: 10.1021/bk-1992-0509.ch001

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ENVIRONMENTAL REMEDIATION

successfully applied to solve a wide variety of s p e c i f i c groundwater contamination problems. However, when one takes into consideration the l i m i t a t i o n s of these "successes", and considers the magnitude and complexity of the cleanup problem that we face today, i t i s evident that current technology i s inadequate. In t h i s context, the need for greater emphasis on the development of new and improved technology has never been greater. By i t s very nature, separation science and technology draws upon the knowledge derived from a large number of science and engineering d i s c i p l i n e s . A comprehensive review of t h i s f i e l d would be an enormous task, and we make no claim to such an objective i n preparing t h i s chapter. Rather, i t i s our objective to provide background information on subsurface contamination and introduce the role of separation science. To t h i s end, we discuss the magnitude and costs associated with the groundwater contamination problem, the regulatory requirements that drive remediation e f f o r t s , important organic and inorganic contaminants, issues associated with environment restoration and give a general l i s t i n g of separation techniques that may apply to environmental restoration. To the extent possible, the reader i s provided key references for more detailed discussions of the various aspects of t h i s important f i e l d . Extent and Cost of Environmental

Remediation

The l i s t of s i t e s that need to undergo environmental restoration i s long and rapidly growing. In 1991» the U.S. Environmental Protection Agency (EPA) (3-5) had estimated that i n the United States there are over 500,000 hazardous chemicals i n use today; over 75,000 registered hazardous waste generators; and over 4500 hazardous waste treatment, storage, and disposal f a c i l i t i e s . This i s further complicated by the number of e x i s t i n g hazardous waste s i t e s . Current estimates, which are acknowledged to be low, are that there are over 25,000 possible hazardous waste s i t e s (4). Another 52,000 municipal l a n d f i l l s , 75,000 on-site i n d u s t r i a l l a n d f i l l s , 180,000 s i t e s with underground storage tanks, and 60,000 abandoned mines s t i l l need to be evaluated more thoroughly. There i s also increased recognition of the extent of environmental contamination within the Department of Energy (DOE) complex (6-Θ). Radioactive groundwater plumes have been i d e n t i f i e d i n the subsurface at many DOE f a c i l i t i e s . Remediation e f f o r t s and the e f f o r t s to develop new and improved technologies have been greatly emphasized by DOE i n the l a s t few years (6). The o v e r a l l waste management problem within the DOE i s compounded by the existence of large amounts of radioactive, hazardous, and radioactive/hazardous mixed waste currently either awaiting f i n a l disposal or requiring processing p r i o r to f i n a l disposal. Recent estimates of these waste inventories have i d e n t i f i e d 180 waste streams and the need for the disposal of over 700,000 m-* of waste (Θ). The majority of t h i s waste (>99Z) i s located at Hanford i n Washington; Rocky F l a t s i n Colorado; Idaho National Engineering Laboratory i n Idaho; Y-12, K-15 and Oak Ridge National Laboratory i n Tennessee; and the Savannah River Plant i n North Carolina.



1. REED ET AL.


Associated with the large number of p o t e n t i a l waste cleanup s i t e s are the r i s i n g cost estimates f o r the environmental restoration of these s i t e s . The methodology by which the cost of cleanup and environmental restoration i s determined i s i t s e l f a controversial issue. Numerous estimates, based on a wide v a r i e t y of assumptions, can be found i n the l i t e r a t u r e . The trend i n cost estimates, however, i s quite readily discerned. In the early summer of 1991, the costs generally quoted f o r environmental restoration were i n the $70-250 b i l l i o n range. By November of the same year (9), Portney put the cost estimate f o r cleaning up a l l c i v i l i a n and m i l i t a r y hazardous waste s i t e s , including Resource Conservation and Recovery Act (RCRA) and Superfund mandates, at $420 b i l l i o n . Just one month l a t e r (10,2), t h i s estimate was raised to $750 b i l l i o n , with the t o t a l possibly surpassing $1 t r i l l i o n . Given that estimated costs of the average Superfund s i t e i s i n the range of $30-50 m i l l i o n (11), t h i s estimate should continue to increase rapidly as additional s i t e s are evaluated and added to the l i s t of hazardous waste s i t e s . The very alarming and rapid increase i n estimates of the cleanup cost results from a combination of (1) an increased recognition of the extent of contamination,(2) changes i n the regulations governing compliance that increase the cleanup "load" and specify more stringent standards, and (3) a growing recognition that we don't have a l l the answers and that technological breakthroughs are needed (12,IS). I t i s p r e c i s e l y t h i s trend i n cost that drives the need f o r both short and long-term research to develop new, improved and c o s t - e f f e c t i v e remediation technology. Laws and Regulations

Pertaining to Environmental Restoration

In preparing t h i s work, we found that one feature of the s o c i e t a l problems, the l e g a l feature, i s of preeminent importance i n d r i v i n g the economic and s c i e n t i f i c side of the remediation effort. However, relevant laws and regulations are not well understood even within the s c i e n t i f i c community. Treatment and disposal of hazardous waste, radioactive waste, and mixed waste are regulated by a myriad of statutes that address e x i s t i n g contamination problems, the management of e x i s t i n g waste, and the f i n a l disposal of t h i s and future waste generated. The most important of these, along with t h e i r i n t e r r e l a t i o n s h i p with various agencies, are shown i n Figure 1. The governing regulatory system i s complex and either d i r e c t l y or i n d i r e c t l y involves a number of applicable (1) federal and state statutes and local ordinances, (2) regulations promulgated by federal, state, and l o c a l agencies, (3) executive orders, and (4) agreements between the involved p a r t i e s . In t h i s section, i t i s our intent to give an overview of only the federal policies (5,14-20) that drive the regulation/remediation of hazardous and nuclear waste. This i s not to downplay the important, and often predominant, role played by the states and l o c a l i t i e s i n the o v e r a l l implementation of hazardous waste management. S t a t e - s p e c i f i c regulations are however largely based on federal law and are frequently more r e s t r i c t i v e than applicable federal regulations. Applicable regulations and


4


AhhbClbD PARTIES


FEDERAL STATUTES

(^ROUNDWATER SOWA

RCRA HSWA

SARA NUCLEAR AEA NWPA

FEDERAL REGULATORS CEQ B>A DOE NRC

Figure 1. Regulations, statutes and agencies that define environmental restoration.

D e f i n i t i o n of Acronyms AEA - Atomic Energy Act CEQ - Council of Environmental Quality CERCLA - Comprehensive Environmental Response, Compensation & L i a b i l i t y Act CWA - Clean Water Act DOE - Department of Energy EPA - Environmental Protection Agency HSWA - Hazardous and Solid Waste Amendment ΝΕΡΑ - National Environmental Policy Act NRC - Nuclear Regulatory Commission NWPA - Nuclear Waste Policy Act RCRA - Resource Conservation and Recovery Act SARA - Superfund Amendments and Reauthorization Act SDWA - Safe Drinking Water Act SWDA - S o l i d Waste Disposal Act


1. REED IT AL.

Environmental Restoration and Separation Science5


s i t e - s p e c i f i c interpretations of decided on a case-by-case basis.

these

regulations

are usually

Regulation of Hazardous Waste. The first broad-reaching l e g i s l a t i o n that brought attention to environmental protection was the National Environmental Policy Act (ΝΕΡΑ - 1969). This act provided the basic national charter for environmental protection that recognized a balance between environmental protection and other factors important to national welfare. Its primary objectives were to (1) prevent environmental damage and (2) ensure that a l l government-agency decision making took environmental factors into account. New a c t i v i t i e s required the writing of environmental impact statements and, i n e f f e c t , made environmental protection the mandate of a l l government agencies. ΝΕΡΑ established the Council on Environmental Quality (CEQ) as the agency responsible for oversight of other federal agencies. The EPA was designated as a co-participant on t h i s council and has been empowered by subsequent l e g i s l a t i o n (primarily the Clean A i r Act - 1970) to act as the implementing arm of ΝΕΡΑ. EPA i s currently chartered to review the environmental impact statements of other agencies. Even with ΝΕΡΑ, i t was not u n t i l the mid 1970s that the problem of groundwater contamination/remediation began to receive a s i g n i f i c a n t amount of attention by the EPA. This occurred primarily due to the passage of three series of laws that related to (1) groundwater protection, (2) hazardous waste management, and (3) waste remediation. These acts combined to bring considerable attention to t h i s important problem of groundwater contamination and greatly increased the importance of managing hazardous wastes. The protection of groundwaters was first addressed i n the enactment of the Federal Water P o l l u t i o n Control Act (FWPCA) i n 1972. This brought groundwater controls under the j u r i s d i c t i o n of the federal government. This was amended to focus on the control of toxic pollutants i n groundwater and renamed the Clean Water Act (CWA) i n 1977. It has been further amended i n 1987 to tighten the discharge standards for toxic pollutants. This act currently provides the mechanism by which water q u a l i t y standards are established. Along the same lines of groundwater protection, the Safe Drinking Water Act (SDWA), passed i n 1974, provided for the safety of public water systems and required the EPA to set national drinking water standards. This was amended i n 1986 to quicken the pace of i t s implementation. The second series of l e g i s l a t i o n defined hazardous waste management. The S o l i d Waste Disposal Act (SWDA), enacted i n 1965, was the f i r s t act passed to regulate waste on a national scale. This was amended by the Resource Conservation and Recovery Act (RCRA), enacted i n 1976, and further amended by the Hazardous and S o l i d Waste Amendments (HSWA) of 1984. These acts c o l l e c t i v e l y provide "cradle to grave" regulation of hazardous waste. Included i n these acts are guidelines for management of s o l i d hazardous waste, provisions for strong federal enforcement of the regulations, a regulatory d e f i n i t i o n of hazardous waste (from which a p r i o r i t y pollutant l i s t was first derived) i n 40 CFR 261.2, a detailed regulatory strategy to address hazardous waste management, an i d e n t i f i c a t i o n of f i n a n c i a l r e s p o n s i b i l i t y for e x i s t i n g waste, and provisions to advance waste-management techniques. Vandegrift et al.; Environmental Remediation ACS Symposium Series; American Chemical Society: Washington, DC, 1992.


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The third series of acts, commonly referred to as CERCLA/superfund acts, provided the federal government with the authority to respond to ( i . e . , clean up) uncontrolled release of hazardous waste. The Comprehensive Environmental Response, Compensation, and L i a b i l i t y Act (CERCLA) was enacted i n 1977. CERCLA applies to the release or threat of release into the environment of any hazardous substance. The broad scope of t h i s statute i s indicated by the fact that "environmental" includes a l l environmental media, and "hazardous substance" i s broadly defined to include not only RCRA "hazardous waste" but a l i s t of substances i d e n t i f i e d by EPA i n 40 CFR 302, which now includes over 700 hazardous substances and over 1500 radionuclides. Whenever there i s a release or threat of a release of a hazardous substance to the environment, EPA i s authorized by the statute to undertake "removal" and/or "remedial" action. CERCLA was amended i n 1986 by the Superfund Amendments and Reauthorization Act (SARA). This changed the cleanup approach, increased the involvement of the public i n cleanup, and established a cleanup fund for superfund s i t e s . The enactment of CERCLA/SARA has spawned a number of related acts that address the n o t i f i c a t i o n of the affected community and response plans. The most important of these are the Emergency Planning and Community Right-To-Know Act (EPCRA) and the National Contingency Plan (NCP) enacted i n 1986 and 1990, respectively. Regulation o f Radioactive and Radioactive/Hazardous M i x e d Waste. The guidelines for the management of waste containing radioactive isotopes were established by the Atomic Energy Act (AEA). Under the provisions of t h i s act, commercial radioactive waste (e.g., spent nuclear f u e l and low-level radioactive medical waste) was regulated by the Nuclear Regulatory Commission and c o d i f i e d i n 10 CFR part 60 through 71. Radioactive waste generated by the defense industry, i n contrast, was regulated by DOE orders. DOE*s current environmental restoration p o l i c y i s to clean up contaminated f a c i l i t i e s and s i t e s within the weapons complex to achieve f u l l compliance with the l e t t e r and intent of the applicable federal, state, and l o c a l statutes (21). The Five Year Plan for Environmental Restoration and Waste Management (6) describes the technologies and research plans currently i d e n t i f i e d . Long-term research plans i n support of subsurface remediation (7) have also been published and are currently being implemented. Hazardous waste that contains radioactive material ( i . e . , mixed waste) i s regulated under both the AEA and RCRA. Under the AEA, the EPA has r e s p o n s i b i l i t y for s e t t i n g r a d i a t i o n protection standards, which are implemented through DOE orders, e.g., Order 5820.2A for DOE radioactive materials (22). This dual regulation further complicates environmental restoration a c t i v i t i e s that involve mixed waste. Regulatory Approach t o S i t e Remediation. Most environmental cleanup standards are derived from the provisions of CERCLA, section 121 "Cleanup Standards" or RCRA, S u b t i t l e C e n t i t l e d "Hazardous Waste Management." The implementing regulations are



1. REED ET AL.


found, respectively, i n 40 CFR part 300 and i n 40 CFR parts 264, 265, and 268. Although CERCLA i s intended to deal with cleanup of past environmental problems and RCRA i s largely intended t o prevent future contamination, both statutes and t h e i r implementing regulations can affect environmental restoration. Although the p r i n c i p a l statutes and regulations that apply to environmental restoration a c t i v i t i e s are c i t e d above, standards that derive from other environmental statutes such as CWA, SDWA, ΝΕΡΑ, and state laws s t i l l apply. In general, state standards may be substituted f o r federal standards when the state standards impose requirements that are at least as stringent as the federal standards. Detailed information on the statutes and the associated implementing regulations can be obtained from the "Environmental Guidance Program Reference Books" prepared by Oak Ridge National Laboratory (16). In addition, an overview of the system of environmental statutes and regulations that govern environmental restoration can be obtained from the reference books "Environmental Law Handbook," "Environmental Statutes," and "State Environmental Law Handbooks" published by Government I n s t i t u t e s , Inc. (17-19). The NCP contains several c r i t e r i a that are intended to guide decisions on the standards to be achieved i n i n d i v i d u a l remedial actions. Among these the most important are the "threshold c r i t e r i a , " which include (1) a general requirement to protect human health and the environment and (2) cleanup standards which have applicable or relevant and appropriate requirements (ARAR). Under the ARAR approach, EPA can use standards from other federal and state statutes (e.g., CWA, SDWA, RCRA) on a case-by-case basis when these requirements are "applicable or relevant and appropriate." For example, RCRA land-disposal restorations (LDR) may be "relevant and applicable" i f a CERCLA remedial action involves RCRA hazardous waste and the waste or i t s hazardous residue i s to be land disposed. In t h i s case, the RCRA LDR standards that are based on the best demonstrated available technology (BDAT) may apply. Environmental restoration a c t i v i t i e s may be conducted under a RCRA, Part Β permit when RCRA hazardous wastes are involved. The RCRA hazardous wastes are i d e n t i f i e d i n 40 CFR 261 and include " c h a r a c t e r i s t i c " hazardous wastes as defined i n subpart C and " l i s t e d " hazardous wastes as defined i n subpart D. The Hazardous and S o l i d Waste Amendment (HSWA) to RCRA includes prohibitions on land disposal of hazardous waste. Under t h i s statute, the EPA has issued regulations (40 CFR 286) that ban the land disposal of untreated hazardous waste and has established treatment standards based on the BDAT. The way that these standards can be involved i n a CERCLA remedial action was discussed above. In addition, technical standards f o r environmental restoration a c t i v i t i e s conducted under a RCRA, Part Β permit are given i n 40 CFR 264, including closure requirements and groundwater concentration l i m i t s (see 40 CFR 264.94). Organic and Metal Restoration

Pollutants

of Importance

t o Environmental

The l i s t of metals, radionuclides, and organic compounds that are now recognized as environmental pollutants continues to grow. The



8


l i s t of 129 p r i o r i t y pollutants i d e n t i f i e d i n RCRA o r i g i n a l l y included 13 metals, with the remainder being organic compounds. When DOE s i t e s are also considered, an additional several hundred radioisotopes are added to t h i s l i s t . The l i s t of organics has grown; over 1000 are now subject to reporting requirements. Any of the estimated 500,000 organics currently i n use have the p o t e n t i a l to be designated as a hazardous material. Numerous l i s t s of p r i o r i t y pollutants e x i s t . It i s important to note that both concentration limits and the l i s t of p r i o r i t y / r e g u l a t e d contaminants are undergoing constant review and are often superseded by l o c a l and state regulations. In t h i s context, we have not t r i e d to tabulate a comprehensive l i s t i n t h i s section. Rather, i t i s our objective to simply i d e n t i f y some of the more important contaminants. This i s important from the perspective of determining the proper emphasis i n the development of separations technology. Regulatory D e f i n i t i o n of Hazardous, Radioactive, and Mixed Waste. E x i s t i n g federal regulations give s p e c i f i c regulatory d e f i n i t i o n s for a l l waste types. Wastes that are of most i n t e r e s t to environmental restoration and waste management are! hazardous waste, radioactive waste, and mixed waste. Hazardous waste i s defined i n 40 CFR part 261.3 as s o l i d waste (as defined i n 40 CFR part 261.2) that (1) i s not excluded from regulation as a hazardous waste under section 262.4 and (2) could cause or s i g n i f i c a n t l y contribute to an increase i n mortality or an increase i n serious i r r e v e r s i b l e or incapacitating r e v e r s i b l e i l l n e s s , or (3) could pose a substantial present or p o t e n t i a l hazard to human health and/or the environment when improperly stored or treated. Materials that are not s o l i d waste and, hence, not subject to regulation as hazardous waste are domestic sewage, i n d u s t r i a l wastewater that q u a l i f i e s as point-source discharges (section 402 of the Clean Water Act as amended), i r r i g a t i o n return flows, nuclear material as defined by the Atomic Energy Act of 1954 (42 U.S.C. 2011 amendment), materials subjected to i n s i t u mining techniques, pulping l i q u o r s , spent s u l f u r i c acid, reclaimed secondary materials, spent wood preserving s o l u t i o n , and the byproducts of producing coke and coal tar i n the s t e e l industry. A d d i t i o n a l l y , a l l s o l i d waste i s not hazardous waste. S o l i d waste excluded are household waste, s o l i d waste generated i n farming and r a i s i n g animals, mining overburden returned to the mine s i t e , waste generated primarily from the combustion of coal and fossil fuels, drilling fluids/wastes associated with oil/gas/geothermal d r i l l i n g , chromium-containing waste i f the waste generator can demonstrate that it will fail the toxicity characteristic. Operationally, a waste i s c l a s s i f i e d as hazardous based on three c r i t e r i a : (1) i t i s l i s t e d as a hazardous waste (40 CFR 261 subpart D); (2) i t has one of the following four c h a r a c t e r i s t i c s : i g n i t a b i l i t y , c o r r o s i v i t y , r e a c t i v i t y , and t o x i c i t y (see 40 CFR 261 subpart C for the s p e c i f i c d e f i n i t i o n of these c h a r a c t e r i s t i c s ) ; or (3) i t f a l l s into the category of "other" hazardous waste (primarily mixtures of non-hazardous materials with hazardous waste).



1. REED ET AL.


The second type of waste i s radioactive waste. This i s nonhazardous waste that i s categorized primarily according to transuranic content and o r i g i n into three c l a s s i f i c a t i o n s : lowl e v e l waste, transuranic (TRU) waste, and high-level waste (HLW). Low-level and TRU waste are defined i n DOE order 5820.2A (see section II.3a). Low l e v e l waste i s radioactive waste that contains less than 100 nCi/g of waste of alpha-emitting transuranics with a >20 year h a l f - l i f e . TRU waste i s radioactive waste that (1) i s not high-level waste and (2) has a s p e c i f i c a c t i v i t y of >100 nCi/g of waste containing transuranic, long-lived alpha emitters. Highl e v e l waste i s defined i n 10 CFR part 60.2 as either (1) i r r a d i a t e d reactor f u e l , (2) l i q u i d waste generated from the f i r s t cycle of solvent extraction i n the processing of nuclear f u e l and subsequent concentrates, or (3) s o l i d s into which such l i q u i d s have been converted. There i s a growing recognition that much of the radioactive waste at DOE s i t e s (7,BS) co-exists with hazardous waste that i s primarily organic i n nature. Waste that contains both radioactive and RCRA-defined hazardous components i s c l a s s i f i e d as mixed waste. This type of waste i s subject to both RCRA and DOE/NRC c o n t r o l , whichever i s the more stringent. Metal Contaminants i n the Environment. From the perspective of environmental remediation, the focus of separation science should be on the metals currently being regulated from the standpoint of groundwater protection. This i s not a hard and fast r u l e , as there are a number of situations (e.g., s p e c i f i c s p i l l s , waste-streams p e c i f i c toxins, etc.) where the focus w i l l be on the removal of a s p e c i f i c hazardous metal compound or substance for which standards have not been set. For example, there i s currently much emphasis within the DOE on uranium contamination at the Fernald S i t e i n Ohio. The metals (excluding radionuclides) currently i d e n t i f i e d for regulation under RCRA/SDWA are l i s t e d i n Table I. The o r i g i n a l l i s t of 13 metals was defined i n the 1986 r e v i s i o n of the SDWA. These include two group II metals (barium and beryllium), eight t r a n s i t i o n metals (cadmium, chromium, copper, lead, mercury, n i c k e l , s i l v e r , and thallium), and three near-transition metals (selenium, arsenic, and antimony). The maximum concentration l i m i t s i n Table I are currently under review, and lower l i m i t s have already been proposed for some metals. In addition to t h i s change, an additional s i x metals have been proposed for consideration. These, as of the January 1991 r e v i s i o n , are aluminum, manganese, molybdenum, strontium, vanadium, and zinc. Promulgation of t h i s l i s t i s i n progress, with groundwater protection guidelines expected to be established i n the near future. The importance of the maximum concentration l i m i t s established to protect groundwaters i n assessing the need for remediation i s not e n t i r e l y c l e a r . CERCLA/superfund cleanup a c t i v i t i e s are not required to achieve these defined groundwater protection l i m i t s . Other factors, such as a v a i l a b i l i t y of technology, background groundwater l e v e l s , and r i s k to health, also need to be considered. The trend, however, appears to be i n the d i r e c t i o n of using the groundwater protection l i m i t s as the target and standard for environmental restoration. Vandegrift et al.; Environmental Remediation ACS Symposium Series; American Chemical Society: Washington, DC, 1992.


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Metals Listed under RCRA/SDWA as P r i o r i t y Pollutants

Table I.


Metals

a

Toxicity L i m i t s (mg/L)

Arsenic Barium Cadmium Chromium Lead Mercury Selenium Silver Antimony Beryllium Copper Nickel Thallium

EPA G u i d e l i n e s (/Ig/L)

b

0

5

5.0 100 1.0 5.0 5.0 0.2 1.0 5.0

10 100 50 2

6 4 1300 100 2

a

0 r i g i n a l l i s t proposed i n the 1986 amendment to the Safe Drinking Water Act. ^Maximum concentration l i m i t s currently defined i n 40 CFR part 261.24 based on the t o x i c i t y c r i t e r i o n . Reference 23, Table 7 and "Drinking Water Limits Set for 23 More Compounds," Chem. Eng. News, 1992, 10(14)» 19. c

Radionuclides i n the Environment. The 1986 amendment of SDWA also addressed the presence of radionuclides i n groundwater from the perspective of r a d i o t o x i c i t y . Table II l i s t s radionuclides currently regulated under EPA/DOE guidelines.

Table I I .

Radioisotopes Currently Regulated under E P A / D O E Guidelines

Concentration Guideline

Radionuclide

Beta p a r t i c l e and photon radioactivity Gross alpha p a r t i c l e a c t i v i t y 0

Radium-226 and -228 Uranium^ Strontium* Plutonium** Cesium 5

b

a

0

Re ference 24, based on dose-to-man of 100 mRem/year calculations s p e c i f i c to the Hanford s i t e .


1. REED ET AL.



Radium and uranium» are associated with the mining and/or presence of uranium deposits i n the subsurface. Regulations pertaining to these are found i n 40 CFR part 192. The other radionuclides are associated with nuclear waste. Groundwater contamination l i m i t s for these are defined by dose-to-man calculations from the perspective of r a d i o t o x i c i t y . There are no isotope or r a d i o n u c l i d e - s p e c i f i c concentration standards for the transuranics from the perspective of t o x i c i t y . By inventory, the following are the radioactive metals that are of most concern: Strontium-90 Technetium-99 Tin-126 Cesium-135, -137 Radium-226 Thorium-230, -232 Uranium-233, -234, -235, -236, -238 Neptunium-237 Plutonium-238, -239, -240, -242 All are long-lived radionuclides and are currently receiving attention, to varying extents, within the DOE as subsurface contaminants that may require remediation. Some of these isotopes appear as both toxic and radiotoxic pollutants. In t h i s event, the more stringent c r i t e r i o n applies. The vast majority of groundwater and subsurface media contaminated with radionuclides are at s i t e s associated with DOE f a c i l i t i e s . Although numerous s i t e - s p e c i f i c reports e x i s t , i t has only been recently that a general study of the levels of contamination at a l l DOE s i t e s was made by Zachara and R i l e y (23). The major observations of t h i s study are the predominance of organics and radionuclide mixtures at e x i s t i n g DOE waste s i t e s . The most important radionuclides i d e n t i f i e d , based on frequency of appearance i n reported analytical r e s u l t s , were plutonium, amerlcium, uranium, neptunium, and cobalt. Organic Species i n the Environment. The predominance of organic species as contaminants i n subsurface media i s r e a d i l y recognized (25-30), They have been described as "the most common healththreatening chemicals detected i n groundwater," and the greatest d i f f i c u l t i e s i n groundwater remediation have been encountered at organic contamination s i t e s (25). The s c i e n t i f i c and technological problems posed by organic contamination range from microscopic considerations, such as the actual d i f f i c u l t y of bringing about a separation or transformation of a given pollutant i n a given environment, to macroscopic considerations such as the huge costs, volumes, and range of materials involved. S p e c i f i c l i s t s that i d e n t i f y p r i o r i t y pollutants have been established. The l i s t of regulated organics (SDWA, 1986) i s given i n Table I I I . This l i s t includes 14 v o l a t i l e organics (primarily halogenated hydrocarbons and benzene), 5 microbial species, and 41 non-volatile organics (pesticides and higher molecular weight solvents). The SDWA p r i o r i t y l i s t for future consideration includes an additional 19 pesticides and 43 synthetic organics. Vandegrift et al.; Environmental Remediation ACS Symposium Series; American Chemical Society: Washington, DC, 1992.

12


RCRA-related controls exist on over 1000 organic species. Approximately 200 of these are currently l i s t e d as acutely hazardous waste, with an additional 350 l i s t e d as hazardous waste. A t o t a l of 250 organics have been i d e n t i f i e d f o r consideration i n establishing groundwater monitoring p r i o r i t y l i s t s (Appendix IX constituents). Groundwater standards are t y p i c a l l y i n the low fig/L range (e.g., 5 μg/L f o r dichloromethane, 2 μg/L for Endrin, 20 μg/L for diquat and 1 μg/L for hexachlorobenzene).


Table I I I . Organic Contaminants Required t o Be Regulated under the SDWA of 1986 V o l a t i l e Organics Trichloroethylene Tetrachloroethylene Carbon tetrachloride 1,1,1-Trichloroethane 1,2-Dichloroethane V i n y l chloride Methylene chloride

Benzene Chlorobenzene Dichlorobenzene Trichlorobenzene 1,1-Dichloroethylene Trans-1,2-Dichloroethylene Cis-1,2-Dichloroethylene

Microbiology and Turbidity Total coliforms Turbidity Giardia lamblla

Viruses Standard plate count Legionella Organics 1,1,2-Trichloroethane Vydate Simazine PAHs PCBs Atrazlne Phthalates Acrylamide Dibromochloropropane (DBCP) 1,2-Dichloropropane Pentachlorophenol Pichloram, Dinoseb Ethylene dibromide (EDB)

Endrin Lindane Methoxychlor Toxaphene 2,4-D 2,4,5-TP Aldicarb Chlordane Dalapon Diquat Endothall Glyphosate Carbofuran Alachlor Epichlorohydrin Toluene Adipates 2,3,7,8-TCDD(Dioxin) Aldicarb sulfone Aldicarb sulfoxide Ethybenzene Heptachlor Heptachlor expoxide Styrene

Xylene Hexachlorocyclopentadiene

SOURCE : Keith, L. H.; T e l l i a r d , W. Α., Environ. TechnoL.

, 1979, 18(4),

Sex.

416.


1. REED ET AL.

13 Environmental Restoration and Separation Science


Issues Associated with Environment Restoration There are a number of issues associated with remediation of contaminated s i t e s that are currently under debate i n the t e c h n i c a l community. The most important of these, the i m p r a c t i c a l i t y of t o t a l remediation, was stated as early as 1980 by the U.S. Geological Survey (SI) i n the following way: "deterioration i n [groundwater] quality constitutes a permanent loss of water resource because treatment of the water or r e h a b i l i t a t i o n of the aquifers i s presently generally impractical." This point has been re-stated i n more recent commentaries (2,12, IS), and the issues of f e a s i b i l i t y , cost, contaminant, prioritization, and o v e r a l l approach to remediation remain. This important debate w i l l continue as more i s learned about both the l i m i t a t i o n s and successes of remediation technology. Although the l i s t of s p e c i f i c issues i s long, a few general issues become clear when the many factors associated with groundwater remediation are considered. The most important of these are: Existing Contaminated Sites •

Complete and total remediation of a l l existing groundwater, although a laudable goal, i s not r e a l i s t i c . This i s due to the enormity of the problem, the l i m i t e d resources available for the task, and i n many instances, the absence of suitable and r e l i a b l e technology to treat the problem to the extent s p e c i f i e d by e x i s t i n g regulations.

•

I t i s important to p r i o r i t i z e e x i s t i n g groundwater problems i n terms of health r i s k / b e n e f i t . This i s a complex issue that includes re-examination of the regulations that drive and define remediation and reinterpretation of the guidelines i n terms of cost and general r i s k .

•

Improved characterization and detection methodology i s needed. The vast majority of monitoring i s s t i l l done by variations on water sampling combined with extensive analysis. Early detection of problems and early detection technology at new waste disposal s i t e s can greatly reduce the extent of contamination.

Future Waste Generated •

Improved waste minimization, documentation, and handling are needed. This i s self-evident, with numerous examples of "past s i n s " i n the l i t e r a t u r e when t h i s was not done.

•

Long-term solutions that meet regulatory c r i t e r i a are needed for waste storage. There are currently no


14


licensed f a c i l i t i e s for the long-term disposal of hazardous mixed waste, high-level nuclear waste, or transuranic waste.


Role of Separation Science i n Environment Restoration Treatments available to environmental remediation f a l l into three broad categories. These are transformation (i.e., destruction), separation, and immobilization. While destruction and immobilization are ends i n and of themselves, separation i s not. In f a c t , separation only makes sense i f i t aids i n a t t a i n i n g one or both of these more permanent solutions. For example, destruction of a hydrocarbon by i n c i n e r a t i o n i s feasible i f i t existed as a 10 wt % aqueous sludge rather than a 100 ppb aqueous solution. F i n a l disposal of 10 kg of plutonium would be less costly and more c e r t a i n than the cleanup of an equivalent amount of plutonium i n 10^ kg of plutonium-contaminated s o i l . A successful separation process should have two products: a low-volume stream containing the contaminant(s) i n a concentrated form and a high-volume stream containing the decontaminated matrix. In general, the concentration of the contaminant(s) i s the easier task. Achieving regulated concentration l i m i t s often c a l l s for very high decontamination levels in the larger-volume, decontaminated product. This, i n some cases, necessitates the removal of 99.9999% of the contaminant. Also, process design requirements for concentrating the contaminant(s) and decontaminating the matrix are generally i n opposition, and a compromise i s struck between these two goals. Because a separation i s not an end i n i t s e l f , the benefits ( i . e . , goals) of a s p e c i f i c separation are c l e a r l y defined by the d i s p o s i t i o n of i t s product streams. Based on the old adage, "a s t i t c h i n time saves nine," waste avoidance i s an area where separations can be of great benefit to the environment. The use of separation technologies to reclaim/recycle materials has become a very important area i n environment restoration, and zero discharge i s quickly becoming the goal of a l l waste producers. As the cost of the disposal of hazardous waste increases, industry has come to recognize that recycle, once more of a public relations e f f o r t , i s now an economic necessity. L a s t l y , the extremely important role of separations i n the analysis of environmental samples should not be overlooked. The interplay of t e c h n i c a l , s o c i e t a l , and l e g a l factors has driven the lower l i m i t s of d e t e c t a b i l i t y and concern to ever decreasing concentrations. The many separations challenges that exist i n t h i s area have been previously noted i n government reports (6, Ύ, SB). Assessment of Available Technology. The v i t a l role of separations and the incentives i n probing i t s f r o n t i e r s have been w e l l recognized at the national l e v e l by two reports i n recent years (SB,S3)* Although few references focus on separations per se, there are i n the l i t e r a t u r e numerous on the whole range of remediation technologies (30,34-41). In addition to t h i s , an excellent source of information i s the l i t e r a t u r e from the EPA (42,43).


1. REED ET AX.



In a compendium of technologies used i n the treatment of hazardous waste (42), technologies are categorized into physical treatment, chemical treatment, b i o l o g i c a l processes, thermal destruction, and f i x a t i o n / s t a b i l i z a t i o n processes. Separation technologies are contained e n t i r e l y within the physical treatment processes section. Those technologies addressed are: • • • • • • • • •

sedimentation centrifugation flocculation oil/water separation dissolved a i r f l o t a t i o n heavy media separation evaporation a i r stripping steam s t r i p p i n g

• • • • • • • • • •

distillation s o i l flushing/washing chelation l i q u i d / l i q u i d extraction s u p e r c r i t i c a l extraction filtration carbon adsorption reverse osmosis ion exchange electrodialysis

In a c o l l e c t i o n of synopses of federal demonstrations of innovative s i t e remediation technologies (4s), technologies are categorized into bioremediatlon, chemical treatment, thermal t r e a t ment, vapor extraction, s o i l washing, s o l i d i f i c a t i o n / s t a b i l i z a t i o n , and other physical treatments. Here separation technologies are contained i n the thermal treatment, vapor extraction, s o i l washing, and other physical treatment sections. Key technologies addressed are : • • • • • • • • • • • • • • • • • • • • • • • • • •

desorption and vapor extraction low-temperature thermal stripping low-temperature thermal treatment radiofrequency thermal s o i l decontamination X*TRAX low-temperature thermal desorption groundwater vapor recovery system i n s i t u s t r i p p i n g with horizontal wells i n s i t u s o i l venting i n s i t u steam/air stripping integrated vapor extraction and steam vacuum s t r i p p i n g Terra Vac i n s i t u vacuum extraction vacuum induced s o i l venting BEST solvent extraction Biogenesis s o i l cleaning system B i o t r o l s o i l washing system debris washing system Ghea Associates process s o i l treatment with Extraksol solvent extraction Carver-Greenfield process f o r extraction of o i l y waste Chemtect gaseous waste treatment freeze separation membrane m i c r o f i l t r a t i o n p r e c i p i t a t i o n , m i c r o f i l t r a t i o n , and sludge dewatering rotary a i r s t r i p p i n g ultrafiltration


16


A number of these technologies are represented i n the contributions to the symposium proceedings that follow t h i s introductory chapter. As reflected i n these contributions, there are clear benefits to almost a l l of these technologies when a suitable environmental restoration problem e x i s t s .


Conclusions and Recommendations The estimated costs of environmental remediation are huge. Regulatory constraints and interpretations are constantly evolving. The technical challenges are staggering. Innovative separation technologies are needed that are economical, acceptable to the public, and e f f e c t i v e . In developing new separations for environmental remediation or waste avoidance, i t i s important to never disconnect the separation operation from the goals of the entire process. These are; • • •

Decontamination of the bulk of the groundwater, s o i l , or waste stream Concentration of the contaminant(s) Assured and economic f i n a l disposal or recycle of the contaminant(s)

Separation i s not an end i n i t s e l f but a means to an end. The d i s p o s i t i o n of a l l effluents must be accounted f o r , and f i n a l disposal of equipment must be planned. In general, the products of waste treatment of environmental remediation have no value, and the governing c r i t e r i a i n successful treatment i s cost minimization. The separation that produces the least expensive disposal of products at the lowest processing cost i s the best process. S o c i a l and regulatory pressures w i l l continue to govern what the most important problems are; economics w i l l continue to drive the choices i n treatments and long-term research emphasis. Work supported by the U.S. Department of Energy under Contract W-31-109-Eng-38. L i t e r a t u r e Cited 1.

2. 3.

4.

5. 6.

"Evaluation of Groundwater Extraction Remedies," O f f i c e of Solid Waste and Engineering Response, United States Environmental Protection Agency, Washington DC, 1989, EPA/540/2-89/054. Abelson, P. Η., "Remediation of Hazardous Waste S i t e s , " S c i . , 1992, 255, 901. "The Eighteenth and Nineteenth Annual Report of the Council on Environmental Quality together with the President's Message to Congress," Council on Environmental Quality, U.S. Department of Commerce, N.T.I.S., 1989, PB90-163148. "Characterization of Municipal S o l i d Waste i n the United States, 1960 to 2000 (Update 1988)," Franklin Associates Ltd., U.S. Environmental Protection Agency, Office of S o l i d Waste, 1988, c i t e d i n reference 3, p. 42. Cooke, S. Μ., The Law of Hazardous Waste; Mathew Bender and Co. Inc.: New York, NY, 1991; Vol. 1-3. "Environmental Restoration and Waste Management - Five Year Plan, F i s c a l Years 1993 - 1997," U.S. Department of Energy, Washington, DC, 1991, FYP DOE/S-0089P. Vandegrift et al.; Environmental Remediation ACS Symposium Series; American Chemical Society: Washington, DC, 1992.

1. REED ET AL.


7.

"Evaluation of Mid-to Long Term Basic Research f o r Environmental Restoration," O f f i c e of Energy Research, U.S. Department of Energy, Washington, DC, 1989, DOE/ER-419. 8. "DOE LDR Strategy Report f o r RMW," U.S. Department of Energy, Washington, DC, 1989, DOE/EH-91002927. 9. Portney, P., Report prepared f o r Resources for the Future, Washington, DC, c i t e d i n Tox. Mat. News, 1991, 18(45), 446. 10. Russell, Μ., "Hazardous Waste Remediation: The Task at Hand," Report f o r The Waste Management Research and Education I n s t i t u t e , The University of Tennessee, Knoxville, TN. Cited


i n Tox. Mat. News,

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11. Cooke, S. Μ., The Law of Hazardous Waste; Mathew Bender and Co.: Inc., New York, NY, 1991; V o l . 1, pp. i v . 12. Rowe, J r . , W. D., "Superfund and Groundwater Remediation: Another Perspective,"

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Regulations; Second Edition; Van Nostrand Reinhold: New York, NY, 1991. "Environmental Guidance Program Reference Books," Oak Ridge National Laboratory, Oak Ridge, TN, 1990, ORNL/M-1277. Environmental Law Handbook; Eleventh e d i t i o n ; Government I n s t i t u t e s , Inc.: Rockville, MD, 1991. Environmental Statutes; Eleventh edition; Government I n s t i t u t e s , Inc.: Rockville, MD, 1991. "State Environmental Law Handbooks," These are s t a t e - s p e c i f i c handbooks on environmental law. Information on these can be obtained by c a l l i n g (301) 251-9250. ΝΕΡΑ Deskbook, Environmental Law I n s t i t u t e : Washington, DC, 1989. EPA Register Notice, July 3, 1986. Interpreted by the DOE i n 1987. "DOE order 5820.2a," U.S. Department of Energy, Washington, DC, 1988. Riley, R. G.; Zachara, J . Μ., "Nature of Chemical Contaminants on DOE Lands and I d e n t i f i c a t i o n of Representative Contaminant Mixtures for Basic Subsurface Science Research," O f f i c e of Energy Research, U.S. Department of Energy, Washington, DC, 1992, DOE/ER-0547T. R. E. Jacquish and R. W. Bryce, "DOE derived Concentration guides based on e f f e c t i v e dose l i m i t not t o exceed 100 millirem/year." Derived from DOE Order 5480.1A: in "Hanford S i t e Environmental; Report f o r Calendar Year 1989" P a c i f i c Northwest Laboratory, Richland, WA, 1990, PNL-7346. Mackay, D. M.; Cherry, J . Α., "Groundwater Contamination: Pump-and-Treat Remediation," Environ. S c i . Technol., 1989, 23, 630.


18


26. Mackay, D. M.; Roberts, P. V.; Cherry, J. Α., "Transport of Organic Contaminents i n Groundwater," Environ. Sci. Technol., 1985, 19, 384. 27. McCarty, P. L.; Reinhard, M.; Rittmann, Β. Ε., "Trace Organics i n Groundwater," Environ. Sci. Technol., 1981, 15, 41. 28. Mongan, T. R., " P r i o r i t y Pollutant C r i t e r i a and the Clean Water Act," Wat. Env. Tech, 1991, December, 38. 29. Perry, A. S.; Muszkat, L.; Perry, R. Υ., " P o l l u t i o n Hazards from Toxic Organic Chemicals," i n "Toxic Organic Chemicals i n Porous Media," Eds: Z. G e r s t l , Y. Chen, U. M i n g l e l g r i n , B. Yaron, Springer-Verlag, B e r l i n , New York, 1989. 30. Heilshorn, E. D., "Removing VOCs from Contaminated Water,"


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31. Meyer, G., "Groundwater Contamination - No 'Quick Fix' i n Sight," USGS yearbook; U.S. Geological Survey: Washington DC, 1980. 32. "Opportunities i n Chemistry," Report of the Committee to Survey Opportunities i n the Chemical Sciences, United States National Research Council, National Academy Press, Washington, DC, 1985. 33. "Frontiers i n Chemical Engineering: Research Needs and Opportunities," Report of the Committee on Chemical Engineering F r o n t i e r s : Research Needs and Opportunities, United States National Research Council, National Academy Press, Washington, DC, 1988. 34. Z i e g l e r , G. J . , "Remediation Through Groundwater Recovery and Treatment," Poll. Eng., 1989, July, 75. 35. "USEPA T r e a t a b i l i t y Manual: Volume I I I . Technologies f o r Control/Removal of Pollutants," Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, 1983, EPA-600/2-82/001a. 36. O ' N e i l l , E. J . , "Working to Increase the Use of Innovative Cleanup Technologies," Wat. Env. Tech., 1991, December, 48. 37. Dworkin, D.; Cawley, Μ., "Aquifer Restoration: Chlorinated Organics Removal Considerations i n Proven vs. Innovative Technology," Env. Prog., 1988, 7, 99. 38. Cheremisinoff, P. Ν., "Water and Wastewater Treatment Fundamentals and Innovations," Poll. Eng., 1989, March, 94. 39. Hauck, J . ; Masoomian, S., "Alternative Technologies for Wastewater Treatment," Poll. Eng., 1990, May, 81. 40. Eaton, D. L.; Smith, T. H.; Clements, T. L.; Hodge, V., "Issues i n Radioactive Mixed Waste Compliance with RCRA: Some Examples from Ongoing Operations at the Idaho National Engineering Laboratory," Idaho National Engineering Laboratory, Idaho F a l l s , ID, 1990, EGG-M-89352. 41. McGlochlin, S. C.; Harder, R. V.; Jensen, R. T.; P e t t i s , S. A.; Roggenthen, D. Κ., "Evaluation of Prospective Hazardous Waste Treatment Technologies for Use i n Processing Low-Level Mixed Wastes at Rocky F l a t s , " EG&G Rocky F l a t s , Inc., Rocky F l a t s Plant, Golden, CO, 1990, RFP-4264.


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42. "A Compendium of Technologies Used i n the Treatment of Hazardous Waste," Center for Environmental Research Information, United States Environmental Protection Agency, C i n c i n n a t i , OH, 1987, EPA/625/8-87/014. 43. "Synopses of Federal Demonstrations of Innovative S i t e Remediation Technologies," Center for Environmental Research Information, United States Environmental Protection Agency, C i n c i n n a t i , OH, 1991, EPA/540/8-91/009.


RECEIVED June 29, 1992


Environmental Restoration and Separation Science - ACS Symposium

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