832307

CHAPTER 5

Technologies forHazardous Waste Management

Contents

PageSummary Findings . . . . . . . . . . . . . . . . . . . . 139Waste Reduction Alternatives , .. ...,, . . . . 139Hazard Reduction Alternatives: Treatment

and Disposal . . . . . . . . . . . . . . . . . . . . . . . . . 139Ocean Use . . + . . . . . . . . . . . . . . . . . . . . . . . . . 140Uncontrolled Sites. . . . . . . . . . . . . . . . . . . . . . 140Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 140Waste Reduction Alternatives . . . . . . . . . . . 141Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 141Source Segregation . . . . . . . . . . . . . . . . . . . . . 142Process Modification . . . . . . . . . . . . . . . . . . . 143End-Product Substitution . . . . . . . . . . . . . . . . 144Recovery and Recycling . . . . . . . . . . . . . . . . . 146Economic Factors . . . . . . . . . . . . . . . . . . . . . . 148Emerging Technologies for

Waste Reduction. . . . . . . . . . . . . . . . . . . . . . 151Hazard Reduction Alternatives: Treatment

and Disposal l *************O.***.*** l 156Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 156Summary Comparison . . . . . . . . . . . . . . . . . . 156Treatment Technologies . . . . . . . . . . . . . . . . . 158Biological Treatment. . . . . . . . . . . . . . . . . . . . 174Landfills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174Surface Impoundments. . . . . . . . . . . . . . . . . . 186Underground Injection Wells . . . . . . . . . . . . 189Comparative Unit Costs for

Selective Technologies. . . . . . . . . . . . . . . . . 195Ocean Disposal and Dispersal . . . . . . . . . . . 198Current Usage l ..***. l O..**** . . . . . . . . . 198Legislative Background. . . . . . . . . . . . . . . . . . 199Controversy Over Ocean Use for

Hazardous Wastes . . . . . . . . . . . . . . . . . . . . 200Future Research and Data Needs . . . . . . . . . 203Technical Regulatory Issues . . . . . . . . . . . . . 204Uncontrolled Sites l ** ** .***0*0***.O*QQO 205Issues Concerning Effectiveness . . . . . . . . . . 205Site Identification and Evaluation ., ....., 207Appendix 5A.-Case Examples of Process

Modifications l *******************e** 213

List of TablesTable No.22.A Comparison of the Four Reduction

Methods ...,.., ..***,** ,.s.,,.. l . * , 14223. Process Modification to the Mercury CeIl 14424. Advantages and Disadvantage of process

PageOptions for Reduction of Waste Streams for VCM Manufacture . . . . . . . . . . . . . . . 144

25. End-product Substitution for Reductionof Hazardous Waste . . . . . . . . . . . . . . . . . 145

26. Commercially Applied RecoveryTechnologies . . . . . . . . . . . . . . . . . . . . . . . 147

27. Description of Technologies CurrentlyUsed for Recovery of Materials . . . . . . . 149

28. Recovery/Recycling Technologies Being

29

30

31

Developed . . . . . . . . . . . . . . . . . . . . . . . . . . 151Conventional Biological TreatmentMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Industries With Experience in ApplyingBiotechnology to Waste Management . . 153Comparison of Some Hazard ReductionTechnologies . . . . . . . . . . . . . . . . . . . . . . . 157

32. Comparison of Thermal TreatmentTechnologies for Hazard Reduction . . .

33. Engineered Components of Landfills:Their Function and Potential Causesof Failure . . . . . . . . . . . . . . . . . . . . . . . . .

34. Comparison of Quoted Prices for NineMajor Hazardous Waste Firms in 1981

35. Incineration v. Treatment: Range ofEstimated Post-RCRA Charges for

l 163

. 177

, 196

Selected Waste Types.. , . .. . . . . . . . . . . 19736. Unit Costs Charged for Services at

Commercial Facilities . . . . . . . . . . . . . . . . 19737. Data Required To Identify and Evaluate

Uncontrolled Sites.. . . . . . . . . . . . . . . . . . 20738. Advantages and Disadvantages of

Control Technologies . . . . . . . . . . . . . . . . 21039. Types of Remedial Action Employed

at a Sample of Uncontrolled Sites .*. ,* 211

List of FlguresFigure No. Page

7. Relative Time Required forImplementation of Reduction Methods . 112

8. Injection Liquid Incineration, . . . . . . . . . 1659, Molten Salt Destruction: Process Diagram 171

10. Generalized Depiction of a HazardousWaste Landfill Meeting MinimumFederal Design Criteria.. .. ..,.........176

11. Potential Failure Mechanisms for Covers 18012. Schematic of Single arid Double Synthetic

Liner Design .*...** ...*,*** ,..0.... l 18613. Schematic of Typical Completion Method

for a DeepWaste Injection Well . . . . . . . 190

CHAPTER 5

Technologies for Hazardous Waste Management

Summary Findings

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Waste Reduction Alternatives

Source segregation is the easiest and mosteconomical method of reducing the volumeof hazardous waste. This method of hazard-ous waste reduction has been implementedin many cases, particularly by large in-dustrial firms. Many opportunities still ex-ist for further application. Any change inmanagement practices should include theencouragement of source segregation.

Through a desire to reduce manufacturingcosts by using more efficient methods, indus-try has implemented various process modifi-cations. Although a manufacturing processoften may be used in several plants, eachfacility has slightly different operating condi-tions and designs. Thus, a modification re-sulting in hazardous waste reduction maynot be applicable industrywide. Also, propri-etary concerns inhibit information transfer.

Product substitutes generally have been de-veloped to improve performance. Hazardouswaste reduction has been a side-benefit, nota primary objective. In the long term, end-product substitution could reduce or elimi-nate some hazardous wastes. Because manydifferent groups are affected by these substi-tutions, there are limitations to implementa-tion.

With regard to recovery and recycling ap-proaches to waste reduction, if extensive re-covery is not required prior to recycling awaste constituent, in-plant operations arerelatively easy. Commercial recovery bene-fits are few for medium-sized generators. Noinvestment is required, but liability remainswith the generator. Commercial recoveryhas certain problems as a profitmaking en-terprise. The operator is dependent on sup-pliers waste as raw material; contaminationand consistency in composition of a wasteare difficult to control. Waste exchanges are

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not very popular at present, since generatorsmust assume all liability in transferringwaste. Also, small firms do not generateenough waste to make it attractive for re-cycling,

Hazard Reduction Alternatives:Treatment and Disposal

Many waste treatment technologies can pro-vide permanent, immediate, and very highdegrees of hazard reduction. In contrast, thelong-term effectiveness of land-based dispos-al technologies relies on continued mainte-nance and integrity of engineered structuresand proper operation. For wastes which aretoxic, mobile, persistent, and bioaccumula-tive, and which are amenable to treatment,hazard reduction by treatment is generallypreferable to land disposal. In general, how-ever, costs for land disposal are comparableto, or lower than, unit costs for thermal orchemical treatment.

For waste disposal, advanced landfill de-signs, surface impoundments, and injectionwells are likely to perform better than theirearlier counterparts. However, there is insuf-ficient experience with these more advanceddesigns to predict their performance. Site-and waste-specific factors and continuedmaintenance of final covers and well plugswill be important. The ability to evaluate theeffectiveness of these disposal technologiescould be improved through better instrumen-tation of these facilities. Currently, their per-formance evaluation relies heavily on moni-toring the indirect effects of their failure by,for example, detecting aquifer contamination.

In comparing waste treatment to disposalalternatives, the degrees of permanent haz-ard reduction immediately achievable withtreatment technologies are overwhelming at-tributes in comparison to land-based dispos-

739

140 l Technologies and Management Strategies for Hazardous Waste Control

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al. However, comparison of these technol-ogies at the very high destruction levels theyachieve is difficult. Difficulties include: mon-itoring methods and detection limits, knowl-edge about the formation of toxic productsof incomplete combustion, and diversity inperformance capabilities among the differ-ent treatments.

Chemical, physical, and biological batch-type treatment processes can be used to re-duce waste generation or to recover valuablewaste-stream constituents. In marked con-trast to both incineration and land disposal,these processes allow checking treatmentresiduals before any discharge to the envi-ronment, In general, processes which offerthis important added reliability are few, butwaste-specific processes are emerging. Re-search and development efforts could en-courage the timely emergence of more ofthis type process applicable to future haz-ardous wastes.

Ocean Use

For some acids and very dilute other hazard-ous wastes, dumping in- ocean locations mayoffer acceptable levels of risk for both theocean environment and human health. How-ever, there is generally inadequate scientific

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information for decisions concerning mosttoxic hazardous wastes and most locations.This is a serious problem since there maybe increasing interest in using the oceans asthe costs of land disposal increase and if pub-lic opposition to siting new treatment facil-ities continues.

Uncontrolled Sites

A major problem is that the National Contin-gency Plan under the Comprehensive Envi-ronmental, Response, Compensation, andLiability Act (CERCLA) does not providespecific standards, such as concentrationlimits for certain toxic substances, to estab-lish the extent of cleanup. There are con-cerns that cleanups may not provide protec-tion of health and environment over the longterm.

The long-term effectiveness of remedial tech-nologies is uncertain. A history of effective-ness has not yet been accumulated. Manyremedial technologies consist of waste con-tainment approaches which require long-term operation and maintenance, In recentremedial actions, removal of wastes and con-taminants, such as soil, accounted for 40 per-cent of the cases; such removed materialswere usually land disposed.

Introduction

The purpose of this chapter is to describe the tion recognizes that where technically and eco-variety of technical options for hazardouswaste management. The technical detail is lim-ited to that needed for examining policy op-tions and regulatory needs. Still, there aremany technologies, and their potential roles inhazardous waste management are diverse.Thus, there are many technical aspects relatedto policy and regulation issues. The reader in-terested in the details of the technologies re-viewed here is encouraged to read beyond thispolicy-oriented discussion.

The first group of technologies discussed arethose which reduce waste volume. This distinc-

nomically feasible, it is better to reduce thegeneration of waste than to incur the costs andrisks of managing hazardous waste. Wastereduction technologies include segregation ofwaste components, process modifications, end-product substitutions, recycling or recoveryoperations, and various emerging technologies.Many waste reduction technologies are close-ly linked to manufacturing and involve propri-etary information. Therefore, there is less de-tailed information in this section than in others.

Much of the chapter discusses technologiesthat reduce the hazard from the waste gener-

Ch. 5 Technologies for Hazardous Waste Management 141

ated. These are grouped as: 1) those treatmentsthat permanently eliminate the hazardouscharacter of the material, and 2) those dispos-al approaches that contain or immobilize thehazardous constituents.

There are several treatments involving hightemperature that decompose materials intoharmless constituents, Incineration is the obvi-ous example, but there are several existing andemerging destruction technologies that aredistinguished in this category. In addition togross decomposition of the waste material,there are emerging chemical technologieswhich detoxify by limited molecular rearrange-ment and recover valuable materials for reuse.Whether by destruction or detoxification, thesetechnologies permanently eliminate the hazardof the material.

Containment chiefly involves land disposaltechniques, but chemical pretreatment meth-ods for stabilization on a molecular level arerapidly emerging, Combining these methods of-fers added reliability, and sectors of industryappear to be adopting that approach. The dis-

cussion of containment technologies includes:1) landfilling, 2) surface impoundments, 3) deep-well injection, and 4) chemical stabilization.

Use of the oceans is considered a technicaloption for some wastes. A number of regula-tory and policy issues emerge concerningocean use and are discussed.

The final section of this chapter concerns un-controlled hazardous waste sites from whichreleases of hazardous materials is probable orhas already occurred. Such sites are often aban-doned and are no more than open dumps. Thesites are addressed by CERCLA. The technicalaspects of identifying, assessing, and remediat-ing uncontrolled sites are reviewed in this sec-tion. There has been limited engineering expe-rience with cleaning up uncontrolled sites.

Many technologies that are applicable to thesame waste compete in the marketplace. Theinitial discussion in the section on hazardreduction treatment and disposal technologiescompares the costs of comparative technolo-gies in some detail.

Waste Reduction Alternatives

Introduction

Four methods are available to reduce theamount of waste that is generated:

1. source segregation or separation,2. process modification,3. end-product substitution, and4. material recovery and recycling.

Often, more than one of these approaches isused, simultaneously or sequentially.

Reduction of the amount of waste generatedat the source is not a new concept. Several in-dustrial firms have established in-house incen-tive programs to accomplish this. One exampleis the 3P programPollution Prevention Paysof the 3M Corp. Through the reduction ofwaste and development of new substitute prod-ucts for hazardous materials, 3M has saved $20

million over 4 years.1 Other firms have estab-lished corporate task forces to investigate solu-tions to their hazardous waste managementproblems, One solution has been recycling andrecovery of waste generated by one plant foruse as a raw material at another corporate-owned facility. Such an approach not onlyreduces waste, but lowers operating costs.

Significant reductions in the volume of wastegenerated can be accomplished through sourcesegregation, process modification, end-productsubstitution, or recovery and recycle. No onemethod or individual technology can be se-lected as the ultimate solution to volume reduc-tion. As shown in figure 7, three of the meth-ods, i.e., source segregation, process modifica-

IM. G. Royston, Pollution Prevention Pays (New York: Perga-mon Press, 1979).


Figure 7.Relative Time Required forImplementation of Reduction Methods

Source separation4 *

u Process modification2% + PE

Recycling/recovery:.

z- *

< End-product substitution2- *

1 I I I Jo 1 2 3 4 5

(Relative units)Time ~

SOURCE. Off Ice of Technology Assessment

tions, and recovery and recycling can be imple-mented on a relatively short- to medium-termbasis by individual generators. End-productsubstitution is a longer term effort. A compari-son of the advantages and disadvantages of

each of the four approaches is given in table22. Because of proprietary concerns and lackof industrywide data, the amount of wastereduction that has already occurred and thepotential for further reduction is difficult toevaluate. A 1981 study by California con-cluded that new industrial plants will produceonly half the amount of hazardous waste cur-rently produced. Other estimates for potentialwaste production range from 30 to 80 percent.3

Waste reduction efforts, however, are more dif-ficult in existing plants.

Source Segregation

Source segregation is the simplest and prob-ably the least costly method of reduction. Thisapproach prevents contamination of large vol-

2Future Hazardous Waste Generation in California, Depart-

ment of Health Services, Oct. 1, 1982.3Joanna D. Underwood, Executive Director, Inform, The New

York Times, Dec. 27, 1982.

Table 22.A Comparison of the Four Reduction Methods

Advantages DisadvantagesSource segregation or separationI) Easy to implement; usually low investment 1) Still have some waste to manage2) Short-term solutionProcess modification1) Potentially reduce both hazard and volume 1) Requires R&D effort; capital investment2) Moderate-term solution 2) Usually does not have industrywide impact3) Potential savings in production costsEnd product substltuflon1) Potentially industrywide impactlarge 1) Relatively long-term solutions

volume, hazard reduction 2) Many sectors affected3) Usually a side benefit of product improvement4) May require change in consumer habits5) Major investments requiredneed growing market

Recovery/recyclingl /n-p/ant1) Moderate-term solution 1) May require capital investment2) Potential savings in manufacturing costs 2) May not have wide impact3) Reduced liability compared to commercial

recovery or waste exchangel Commercial recovery (offsite)1) No capital investment required for 1) Liability not transferred to operator

generator 2) If privately owned, must make profit and return investment2) Economy of scale for small waste 3) Requires permitting

generators 4) Some history of poor management5) Must establish long-term sources of waste and markets6) Requires uniformity in composition

l Waste exchange1) Transportation costs only 1) Liability not transferred

2) Requires uniformity in composition of waste3) Requires long-term relationshipstwo-party involvement

SOURCE: Office of Technology Assessment.


umes of nonhazardous waste by removal ofhazardous constituents to forma concentratedhazardous waste, For example, metal-finishingrinse water is rendered nonhazardous by sepa-ration of toxic metals. The water then can bedisposed through municipal/industrial sewagesystems.

However, there are disincentives, particular-ly for small firms wishing to implement sourcesegregation. For example, an electroplatingfirm may, for economic reasons, mix wastescontaining cyanides and toxic metals with awaste that contains organics. The waste streamis sent to the municipal treatment system. Themunicipal system can degrade the organics,but the metals and cyanide accumulate in thesludge, which is disposed as a nonhazardoussolid waste in a sanitary landfill. As long as thefirm dilutes the cyanide and metals concentra-tions to acceptable limits for municipal dispos-al, it is in compliance with the EnvironmentalProtection Agencys (EPA) regulations. If thefirm calculates the costs of recovering thecyanide onsite, the cost may be more than thefees paid to the municipal treatment facility.Thus, there is no economic incentive for sourcesegregation, which would yield a hazardouswaste, although the public would benefit ifsource segregation were practiced. Alternative-ly, accumulation of such sludges can lead tosignificant levels of toxic material in sanitarylandfills. Municipal treatment facilities are fi-nanced with tax dollars, In this example, thepublic is, in essence, subsidizing industrialwaste disposal, Moreover, to carry out sourcesegregation, a firm may have to invest in newequipment.

Process Modification

Process modifications are, in general, madeon a continuous basis in existing plants to in-crease production efficiencies, to make productimprovements, and to reduce manufacturingcosts, These modifications may be relativelysmall changes in operational methods, such asa change in temperature, in pressure, or in rawmaterial composition, or may involve majorchanges such as use of new processes or newequipment. Although process modifications

have reduced hazardous wastes, the reductionusually was not the primary goal of the modifi-cations. However, as hazardous waste manage-ment costs increase, waste reduction will be-come a more important primary goal.

Three case examples were studied to analyzeincentives and impacts for process modifica-tions for hazardous waste reduction. The fol-lowing factors are important:

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A typical process includes several steps.Although a change in one step may besmall relative to the entire process, thecombination of several changes often rep-resents significant reductions in cost,water use, or volume of waste.A change in any step can be made inde-pendently and is evaluated to determinethe impact on product, process efficiency,costs, labor, and raw materials.Generally, process modifications are plant-or process-specific, and they cannot be ap-plied industrywide.A successful process change requires adetailed knowledge of the process- as wellas a knowledge of alternative materialsand processing techniques. Successful im-plementation requires the cooperative ef-forts of material and equipment suppliersand in-house engineering staffs.

Three process changes are discussed in detailin the appendix to this chapter and are brieflysummarized below:

1. Chlor-alkali industry .-Significant proc-ess developments in the chlor-alkali indus-try (which produces, e.g., chlorine andcaustic soda) have resulted in reduction ofmajor types of hazardous waste throughmodifications to the mercury electrolysiscell. The effects on waste generation aresummarized in table 23. The modificationswere not developed exclusively to reducehazardous waste, but were initiated pri-marily to increase process efficiency andreduce production costs.

2. Vinyl chloride (plastics) production.Several process options are available forhandling waste from the production ofvinyl chloride monomers (VCMs). Five al-

144 . Technologies and Management Strategies for Hazardous Waste Control

3.

Table 23.Process Modifications to the Mercury Cell

Modification Effect on waste stream Reason for modificationDiaphragm cell Elimination of mercury Preferred use of natural salt

contaminated waters brines as raw materialDimensionally stable anode Elimination of chlorinated Increased efficiency

hydrocarbon wasteMembrane cell Elimination of asbestos Reduce energy costs; higher

diaphragm waste quality product, -SOURCE Off Ice of Technology Assessment

ternatives are illustrated in table 24. Allfive have been demonstrated on a commer-cial scale. In most cases, the incinerationoptions (either recycling or add-on treat-ment) would be selected over chlorinolysisand catalytic fluidized bed reactors. Chlo-rinolysis has limited application becauseof the lack of available markets for the endproducts. If further refinements could bemade to the catalytic process, such ashigher concentration of hydrogen chloride(HCl) in the gas stream which would allowit to be used with all oxychlorinationplants, its use could be expanded.Metal-finishing industry .-Several modi-fications in metal cleaning and platingprocesses have enabled the metal-finishingindustry to eliminate requirements for on-site owned and operated wastewater treat-ment facilities. By changing these proc-esses to eliminate formation of hazardous

sludge, the effluent can be discharged di-rectly to a municipal wastewater treatmentfacility, saving several million dollars incapital investment.

End-Product Substitution

End-product substitution is the replacementof hazardous waste-intensive products (i.e., in-dustrial products the manufacture of which in-volves significant hazardous waste) by a newproduct, the manufacture of which would elim-inate or reduce the generation of hazardouswaste. Such waste may arise from the ultimatedisposal of the product (e.g., asbestos products)or during the manufacturing process (e.g., cad-mium plating).

Table 25 illustrates six examples of end-prod-uct substitution, each representing a differenttype of problem. General problems include thefollowing:

Table 24.Advantages and Disadvantages of Process Options for Reduction ofWaste Streams for VCM Manufacture

Treatment option Type Advantages DisadvantagesHigh-efficiency incineration of

vent gas only

High-efficiency incinerationwithout HCI recovery

High-efficiency incinerationwith HCI recovery

Chlorinolysis

Catalytic fluidized bed reactor

Add-on treatment 1.2.

Add-on treatment 1.2.

Recycling 1.2.

3.Modi f icat ion of 1.

process

Recycling 1.2.

Relatively simple operationRelatively low capitalinvestmentRelatively simple operationRelatively low capitalinvestmentHeat recoveryRecover both gaseous andliquid componentsHigh reliabilityCarbon tetrachloride generated

Low temperatureDirect recycle of exit gas (no

1. Second process required tohandle liquid waste stream

1. Loss of HCI

1. Exit gas requires scrubbing2. Requires thorough operator

training3. Auxiliary fuel requirements1. High temperatures and

pressures required2. High capital investment costs3. Weakening market for carbon

tetrachloride1. Limited to oxychlorination

plantstreatment required)

SOURCE Office of Technology Assessment,

Ch. 5 Technologies for Hazardous Waste Management l 145

Table 25.End-Product Substitutes for Reduction of Hazardous Waste

Ratio of waste:a Ratio of waste:aProduct Use original product Available substitute substitute productAsbestos Pipe 1.09

Friction products 1.0+ manufacturing(brake linings) waste

Insulation 1.0+ manufacturing

PCBs Electrical transformers 1.0

Cadmium Electroplating 0.29Creosote treated wood PilingChlorofluorocarbons Industrial solvents 70/81 =0.9

DDT Pesticide 1.0+ manufacturingwaste

aQuantity of hazardous waste generated/unit of productSOURCE Office of Technology Assessment

Not all of the available substitutes avoidthe production of hazardous waste. F o rexample, in replacing asbestos pipe, theuse of iron as a substitute in pipe manu-facturing generates waste with phenols andcyanides; and also, during the manufactureof polyvinyl chloride (PVC) pipe, a hazard-ous vinyl chloride monomer is emitted.4

Substitution may not be possible in allsituations. For example, although a sub-stantial reduction in quantity of hazardouswaste generated is achieved by using claypipes, clay is not always a satisfactory re-placement for asbestos.5

Generally, development of substitutes is moti-vated by some advantage, either to a user, (e.g.,in improved reliability, lower cost, or easieroperation), or to the manufacturer (e. g., re-duced production costs). A change in consum-er behavior also may cause product changes. ...

4Sterling-Hobe Corp., Alternatives for Reducing HazardousWaste Generation Using End-Product Substitution, prepared forMaterials Program, OTA, 1982.

5Ibid.

For

IronClayPVC

Glass fiberSteel woolMineral woolsCarbon fiberSintered metalsCementGlass fiberCellulose fiberOil-filled transformersOpen-air-cooled

transformersZinc electroplatingConcrete, steelMethyl chloroform;

methylene chlorideOther chemical

pesticides

0.1 phenols, cyanides,0.05 fluorides0.04 VCM manufacture +1.0 PVC pipeo

0.2

00

0.06

0.0 (reduced hazard)0.9 (reduced hazard)

(reduced hazard)1.0+ manufacturing

waste

example, increased use of microwaveovens has increased the demand for paper andStyrofoam packaging to replace aluminum.Most end-product substitutions aimed at re-duced generation of hazardous waste, how-ever, do not have such advantages. The onlybenefit may be reduction of potential adverseeffects on human health or the environment,Unless the greater risks and costs of hazardouswaste management are fully internalized bywaste generators, other incentives may beneeded to accomplish end-product substitution.

In addition to the approach in chapter 3, op-tion III, end-product substitution may be en-couraged by:

1. regulations,2. limitation of raw materials,3. tax incentives,4. Federal procurement practices, and5. consumer education.

Regulations have been used to prohibit spe-cific compounds. For example, bans on certainpesticides such as dichlorodiphenyltrichloro-


ethane (DDT) have resulted in developmentand use of other chemicals. Legislative prohibi-tion of specific chemicals, such as polychlori-nated biphenyls (PCBs), is another option.

Limiting the supply of raw materials requiredfor manufacture is another method of encour-aging end-product substitution. For example,limiting either the importation or domesticmining of asbestos might encourage substitu-tion of asbestos products. A model for thismethod is the marketing-order system of theU.S. Department of Agriculture, used to per-mit the cultivation of only specified quantitiesof selected crops. Using similar strategies, araw material like asbestos could be controlledby selling shares of a specified quantity of themarket permitted to be mined or imported.

Tax incentives are another means to forceend-product substitution. Excise taxes on prod-ucts operate as disincentives to consume andhave been implemented in the past (e.g., taxeson alcohol, cigarettes and gasoline). This typeof taxation might be incorporated to encourageproduct substitution. The design and accept-ance of a workable, easily monitored tax sys-tem, however, might be difficult to develop.

Federal procurement practices and productspecifications can have significant influenceon industrial markets. Changes in military pro-curement were proposed in 1975 to allow forsubstitution of cadmium-plating by other mate-rials. A change in product specifications to per-mit this substitution would affect not only thequantity of cadmium required for military use,but also might impact nonmilitary applications.

A public more aware of the hazard associ-ated with production of specific productsmight be inclined to shift buying habits awayfrom them.

Larger Economic Contexts. -If a substitution re-quires a complete shift in industrial markets(e.g., if a product manufactured with asbestosis replaced by one made with cement), the im-pact may be largeboth manufacturers andsuppliers may be affected. In addition, userswill be impacted according to the relative mer-its of the products. Other sectors potentially af-

fected by end-product substitution include im-porters of raw materials, exporters of the orig-inal product, and related equipment manufac-turers.

Generally, a product substitution offers a costadvantage over the original product, whichcounters market development expenditures.Potential savings can be achieved by the intro-duction of product substitutes-e. g., increaseddemand may require increased production,thus reducing the cost per unit. Incentives orthe removal of disincentives, however, maybenecessary to increase product demand by a suf-ficient margin to give the substitute a morecompetitive marketplace position,

A significant factor in the introduction of asubstitute product is the stage of growth for ex-isting markets. For example, if the market forasbestos brake lining is declining or growingat a very slow rate, or if large capital invest-ments are required for development of a substi-tute lining, introduction of a substitute may notbe economically practical. The availability ofraw materials also affects the desirability ofsubstitutes. If the original product is dependenton limited supplies of raw materials, substi-tutes will be accepted more rapidly.

Recovery and Recycling

Recovery of hazardous materials from proc-ess effluent followed by recycling provides anexcellent method of reducing the volume ofhazardous waste. These are not new industrialpractices. Recovery and recycling often areused together, but technically the terms are dif-ferent. Recovery involves the separation of asubstance from a mixture. Recycling is the useof such a material recovered from a processeffluent. Several components may be recoveredfrom a process effluent and can be recycled ordiscarded. For example, a waste composed ofseveral organic materials might be processedby solvent distillation to recover halogenatedorganic solvents for recycling; the discardedresidue of mixed organics might be burned forprocess heat.


Materials are amenable to recovery and re-cycling if they are easily separated from proc-ess effluent because of physical and/or chem-ical differences. For example, inorganic saltscan be concentrated from aqueous streams byevaporation, Mixtures of organic liquids canbe separated by distillation. Solids can be sepa-rated from aqueous solutions through filtration.Further examples of waste streams that are eas-ily adaptable to recovery and recycling arelisted in table 26,

Recovery and recycling operations can bedivided into three categories:

1. In-plant recycling is performed by thewaste (or potential waste) generator, andis defined as recovery and recycling of rawmaterials, process streams, or byproductsfor the purpose of prevention or elimina-tion of hazardous waste. (Energy recoverywithout materials recovery is not includedin this discussion of in-plant recycling,but is discussed later in this chapter as atreatment of wastes.) If several productsare produced at one plant by various proc-esses, materials from the effluents of oneprocess may become raw materials foranother through in-plant recycling. An ex-ample is the recovery of relatively dilutesulfuric acid, which is then used to neu-tralize an alkaline waste, In-plant recy-cling offers several benefits to the manu-facturer, including savings in raw materi-als, energy requirements, and disposal ortreatment costs, In addition, by reducingor eliminating the amount of waste gener-ated, the plant owner may be exemptedfrom some or all RCRA (Resource Conser-vation and Recovery Act) regulations,

2.

3.

Commercial (offsite) recovery can be usedfor those wastes combined from severalprocesses or produced in relatively smallquantities by several manufacturers. Com-mercial recovery means that an agentother than the generator of the waste ishandling collection and recovery. Theserecovery systems may be owned and oper-ated by, or simply serve, several waste gen-erators, thereby offering an advantage ofeconomy of scale. In most cases commer-cial recovery systems are owned and oper-ated by independent companies, and areparticularly important for small waste gen-erators. In commercial recovery, responsi-bility for the waste and compliance withregulations and manifest systems remainsthat of the generator until recovery andrecycling is completed.Material exchanges (often referred to aswaste exchanges) are a means to allowraw materials users to identify waste gen-erators producing a material that could beused. Waste exchanges are listing mecha-nisms only and do not include collection,handling, or processing, Although benefitsoccur by elimination of disposal and treat-ment costs for a waste as well as receiptof cash value for a waste, responsibility formeeting purchaser specifications remainswith the generator, *

Standard technologies developed that can beadapted for recovery of raw materials or by-products may be grouped in three general cate-

*For a discussion of the problems being encountered withusing waste exchanges for hazardous waste see IndustrialWaste Exchange: A Mechanism for Saving Energy and Money,Argonne National Laboratory, July 1982,

Table 26.Commercially Applied Recovery Technologies

Generic waste Typical source of effluent Recovery technologiesSolids in aqueous suspension Salt/soda ash liming operations FiltrationHeavy metals Metal hydroxides from metal-plating waste; Electrolysis

sludge from steel-pickling operationsOrganic liquids Petrochemicals/mixed alcohol DistillationInorganic aqueous solution Concentration of inorganic salts/acids EvaporationSeparate phase solids, grease/oil Tannery waste/petroleum waste Sedimentation/skimmingChrome salt solutions Chromium-plating solutions/tanning solutions ReductionMetals; phosphate sulfates Steel-pickling operations PrecipitationSOURCE Off Ice of Technology Assessment


gories. Physical separation includes gravitysettling, filtration, flotation, flocculation, andcentrifugation. These operations take advan-tage of differences in particle size and density,Component separation technologies distin-guish constituents by differences in electricalcharge, boiling point, or miscibility. Examplesinclude ion exchange, reverse osmosis, elec-trolysis, adsorption, evaporation, distillation,and solvent extraction. Chemical transforma-tion requires chemical reactions to removespecific chemical constituents. Examples in-clude precipitation, electrodialysis, and oxida-tion-reduction reactions. These technologiesare reviewed in table 27.

A typical recovery and recycling system usu-ally uses several technologies in series. There-fore, what may appear as a complex processactually is a combination of simple operations.For example, recylcing steel-pickling liquorsmay involve precipitation, gravity settling, andflotation. Precipitation transforms a compo-nent of high volubility to an insoluble substancethat is more easily separated by gravity settling,a coarse separation technique, and flotation,a finishing separation method, Integration ofprocess equipment can introduce some com-plexity, The auxiliary handling equipment (e.g.,piping, pumps, controls, and monitoring de-vices that are required to provide continuoustreatment from one phase to another) can beextensive. A detailed description of the re-cycling and recovery of pickling liquors fromthe steel industry is provided in the appendixat the end of this chapter,

Recovery and recycling technologies appliedto waste vary in their stages of development.Physical separation techniques are the mostcommonly used and least expensive. The sepa-ration efficiency of these techniques is not ashigh as more complex systems, and thereforethe type of waste to which it is applied is lim-ited. Complex component separations (e.g., re-verse osmosis) are being investigated for appli-cation to hazardous waste. These generally areexpensive operations and have not been imple-mented commercially for hazardous waste re-duction. Chemical transformation methods arealso expensive. Precipitation and thermal oxi-

dation, however, appear to have current com-mercial application in hazardous waste man-agement.

Table 28 illustrates some technologies cur-rently being investigated for application towaste recovery and recycle. An expanded dis-cussion of emerging new technologies, specif-ically in phase separation is provided in thefollowing section of this chapter.

Economic Factors

These factors include:

1.

2.

3.

4.5.

6.

7.

8.

research and development required priorto implementation of a technology;capital investment required for new rawmaterial, or additional equipment; i.e., re-covery and recycle equipment, controlequipment, and additional instrumenta-tion;energy requirements and the potential forenergy recovery;improvements in process efficiency;market potential for recycled material,either in-house or commercially, and antic-ipated revenues;management costs for hazardous waste be-fore use of recovery and recycle technol-ogy;waste management cost increases, result-ing from recovery/recycling, i.e., addition-al manpower, insurance needs, and poten-tial liability; andthe value of improved public relations ofa firm.

Because of the number of processing steps in-volved, recovery and recycling can be more ex-pensive than treatment and disposal methods.Earned revenue for recovered materials, how-ever, may counter the cost of recovery.

Many market and economic uncertaintiesmust be considered in an evaluation of pro-posed technology changes. For example, if de-regulation of oil and natural gas results in anincrease in energy costs, additional energy re-quirements, and/or credits earned for energyrecovery from a process could be affected. Theuncertainty of continued availability of a nec-

Table 27.Description of Technologies Currently Used for Recovery of Materials . . . Economics Types of waste streams Separation efficiency Industrial applicationsTechnology/description stage of developmentPhysical separation:Gravity settling:

Tanks, ponds provide hold-uptime allowing solids tosettle; grease skimmed tooverflow to another vessel

Filtration:Collection devices such as

screens, cloth, or other;liquid passes and solidsare retained on porousmedia

Flotation:Air bubbled through Iiquid to

collect finely divided solidsthat rise to the surfacewith the bubbles

Flocculation:Agent added to aggregate

solids together which areeasily settled

Centrifugation:Spinning of liquids and

centrifugal force causesseparation by differentdensities

Component separationDistillation:

Successfully boiling off ofmaterials at differenttemperatures (based ondifferent boiling points)

Evaporation:Solvent recovery by boiling

off the solvent

ion exchange:Waste stream passed through

resin bed, ionic materialsselectively removed byresins similar to resinadsorption. Ionic exchangematerials must beregenerated

Ultrafiltration:Separation of molecules by

size using membraneReverse osmosis:

Separation of dissolvedmaterials from liquidthrough a membrane

Relatively inexpensive; Slurrries with separate phasedependent on particle size solids, such as metal

Limited to solids (largeparticles) that settle quickly(less than 2 hours)

industrial wastewatertreatment first step

Commonly used inwastewatertreatment and settling rate

Labor intensive: relativelyinexpensive; energyrequired for pumping

hydroxide

Tannery waterCommonly used Aqueous solutions with finelydivided solids; gelatinoussludge

Good for relatively largeparticles

Commercialapplication

Relatively inexpensive Aqueous solutions with finelydivided solids

Good for finely divided solids Refinery (oil/water mixtures);paper waste; mineralindustry

Aqueous solutions with finelydivided solids

Good for finely divided solids

Fairly high (90/0)

Refinery; paper waste; mineindustry

Commercial practice Relatively inexpensive

PaintsPracticed commer-cially for small-scale systems

Competitive with filtration Liquid/liquid or liquid/solidseparation, i.e., oil/water;resins; pigments fromlacquers

Solvent separations;chemical and petroleumindustry

Commercial practice Energy intensive Organic Iiquids Very high separationsachievable (99 + 0/0concentrations) of severalcomponents

Organic/inorganic aqueousstreams; slurries, sludges,i.e., caustic soda

Very high separations ofsingle, evaporatedcomponent achievable

Rinse waters from metal-plating waste

Commercial practice inmany industries

Energy intensive

Relatively high costs Fairly high Metal-plating solutionsNot common for HW Heavy metals aqueoussolutions; cyanide removed

Metal-coating applications

Not used Industrially

Some commercialapplication

Relatively high

Relatively high

Heavy metal aqueoussolutions

Fairly high

Heavy metals; organics,inorganic aqueous solutions

Good for concentrationsless than 300 ppm

Not common: growingnumber of applicationsas secondary treat-ment process suchas metal-platingpharmaceuticals

Table 27.Description of Technologies Currently Used for Recovery of MaterialsContinued

Technology/description Stage of development Economics Types of waste streams Separation efficiency Industrial applicationsElectrolysis:

Separation of positively/ Commercial technology; Dependent on concentrations Heavy metals; ions from Good Metal platingnegatively charged not applied to recoverymaterials by application of of hazardous materialselectric current

Carbon/resin absorption:Dissolved materials Proven for thermal Relatively costly thermal

selectively absorbed in regeneration of regeneration; energycarbon or resins. carbon; less practical intensive

aqueous solutions; copperrecovery

Organics/inorganics fromaqueous solutions with lowconcentrations, i.e., phenols

Good, overall effectiveness Phenolicsdependent onregeneration method

Absorbents must beregenerated

Solvent extraction:Solvent used to selectively

dissolve solid or extractliquid from waste

for recovery ofadsorbate

Commonly used inindustrial processing

Relatively high costs forsolvent

Organic liquids, phenols, acids Fairly high loss of solvent Recovery of dyesmay contribute tohazardous waste problem

Chemical transformation:Precipitation:

Chemical reaction causesformation of solids whichsettle

Electrodialysis:Separation based on

differential rates ofdiffusion throughmembranes. Electricalcurrent applied toenhance ionic movement

Chlorinolysis:Pyrolysis in atmosphere of

excess chlorineReduction:

Oxidative state of chemicalchanged through chemicalreaction

Common Relatively high costs Lime slurries Good Metal-plating wastewatertreatment

Commercial technol-ogy, not commer-cial for hazardousmaterial recovery

Moderately expensive Separation/concentration ofions from aqueous streams;application to chromiumrecovery

Fairly high Separation of acids andmetallic solutions

Commercially used inWest Germany

Insufficient U.S. market forcarbon tetrachloride

Chlorocarbon waste Good Carbon tetrachloridemanufacturing

Good Chrome-plating solutionsand tanning operations

Commercially appliedto chromium; mayneed additionaltreatment

Inexpensive Metals, mercury in dilutestreams

Chemical dechlorination:Reagents selectively attack

carbon-chlorine bondsThermal oxidation:

Thermal conversion ofcomponents

Common Moderately expensive

Relatively high

PCB-contaminated oils

Chlorinated organic liquids;

High Transformer oils

Extensively practiced Fairly high Recovery of sulfur, HCIsilver

aGood implies 50 to 8O percent efficiency, fairly high implies 80 percent, and very high Implies 90 percentSOURCE: Office of Technology Assessment.


Table 28.Recovery/Recycling Technologies Being Developed

Technology Development needs Potential applicationIon exchange

Adsorption

Electrolysis

Extract ion

Reverse osmosis

Evaporation

ReductionChemical

dehalogenation

Commercial process for otherapplications (desalinization),applications to metal recoveryunder development. Not economicat present due to investmentrequirements

R&D on new resins andregeneration methods

Cathode/anode, materialdevelopment for membranes

Reduction in loss of acid orsolvent in process

Membrane materials, operatingconditions optimized,demonstration of process

Efficiency improvement/demonstration of process

Efficient collection techniquesEquipment development for

applications to halogenatedwaste other than PCB oils

Chromium recovery; metalplating waste

Organic liquids with or withoutmetal contamination;pesticides

Metallic/ionic solution

Extraction of metals with acids

Salt solutions

Fluorides from aluminumsmelting operation

MercuryHalogenated organics

SOURCE Off Ice of Technology Assessment

essary raw material could influence a decisionfor recovery of materials from waste streams.Uncertainties in interest rates may discourageinvestment and could thus increase a requiredrate-of-return projected for a new project.Changes in allowable rates of capital equip-ment depreciation also may affect costs signif-icantly.

In addition, changes in RCRA regulations foralternative management options (e.g., landfill-ing, ocean dumping, and deep-well injection)affect disposal costs. Stricter regulations orprohibitions of certain disposal practices forparticular wastes could increase the attractive-ness of recycling and recovery operations.However, if hazardous wastes are stored forlonger than 90 days, current regulations re-quire permits for that facility. If large quantitiesof a waste must accumulate (for economic rea-sons) prior to recycling or recovery, the per-mit requirement may discourage onsite re-cycling,

Previously, recovery and recycling was con-sidered as an in-plant operation only; i.e., mate-rial was recovered and recycled within oneplant. Currently, larger corporations are begin-ning to evaluate recovery opportunities on a

broader scale. Recycling within the corporateframework is gaining greater attention as a costreduction tool with an added benefit of reduc-ing public health risks.

Emerging Technologies for Waste Reduction

Although the effects are more difficult to pre-dict, some technological developments havepotential for the reduction of hazardous waste,For example, developments in the electronicsindustry have provided instrumentation andcontrol systems that have greater accuracythan was possible just a few years ago. Thesesystems provide more precise control of proc-ess variables, which can result in higher effi-ciency and fewer system upsets, and a reduc-tion in hazardous waste. The application andimprovements of instrumentation and controlsystems vary with each process. Thus, as newplants are constructed and fitted with newtechnologies, smaller quantities of hazardouswaste will be generated. The technologies thatare discussed in this section have a direct im-pact on the volume and hazard level of wastecurrently generated through one or more of thereduction methods discussed earlier.


Segregation Technology .New developments insegregation technology can increase recoveryand recycling of hazardous waste. Notably,membrane segregation techniques have sub-stantially improved, Membrane separation hasbeen used to achieve filtration, concentration,and purification. However, large-scale applica-tions, such as those required in pollution con-trol have been inhibited by two factors: 1) re-placement costs associated with membrane useand 2) technical difficulties inherent in produc-ing large uniform surface areas of uniformquality. Because of the inherent advantages ofmembrane separation over more conventionalseparation techniques like distillation or evapo-ration, further development of membrane sep-aration for large-scale commercial applicationsis attractive. These advantages include lowerenergy requirements resulting in reduced oper-ating costs and a simpler, more compact sys-tem that generally leads to reduced capitalcosts. Commercial applications exist for all butcoupled transport designs, which are still at thelaboratory stage. All of these illustrated systemshave possible application for reduction of haz-ardous waste. However, microfiltration, ultra-filtration, reverse osmosis, and electrodialysisprocesses have more immediate application,Dialysis has been used on only a small scale;the high flow systems generally typical of haz-ardous waste treatments make its use imprac-tical. Gas separations by membranes do nothave immediate application to hazardous wasteuse. The development of new materials for bothmembranes and supporting fabrics and the useof new layering techniques (e. g., compositemembranes) have led to improved permeabilityand selectivity, higher fluxes, better stability,and a reduced need for prefiltering and stagedseparations.

Improved reliability is the most importantfactor in advancement of membrane separa-tions technology. New types of membraneshave demonstrated improved performance,Thin-film composites that can be used inreverse osmosis, coupled transport, and elec-trolytic membranes have direct application tothe recovery and reduction of hazardous mate-rials from a processing stream.

The major cost in a membrane separationsystem is the engineering and developmentwork required to apply the system to a particu-lar process. Equipment costs are secondary;membranes generally account for only 10 per-cent of system costs. However, membranesmust be replaced periodically and sales of re-placement membranes are important to mem-brane production firms. Currently the largestprofit items are for high-volume flow situations(e.g., water purification) or for high-value prod-uct applications (e. g., pharmaceutical produc-tions). Over 20 companies cover the membranemarket; the largest company is Millipore with1980 total sales of $255 million.

The predicted market growth rate for mem-brane segregations is healthy, generally 10 to20 percent annually of the present membranemarket ($600 million to $950 million). Chlor-alkali membrane electrodialysis cells for theproduction of chlorine and sodium hydroxidelead the projected application areas in hazard-ous waste with growth rates of 25 to 40 per-cent of the present market ($10 million to $15million), The recovery of chromic acid fromelectroplating solutions by coupled transportalso has direct application for the reduction ofhazardous waste. Other uses include ultrafiltra-tion of electrocoat-painting process waste andwaste water recovery by reverse osmosis. Theuse of membrane segregation systems in pre-treatment of hazardous waste probably is thelargest application for the near future.

Biotchnology.-Conventional biological treat-ments have been used in industrial waste treat-ment systems for many years (see tables 29 and30). Recent advances in the understanding ofbiological processes have led to the develop-ment of new biological tools, increasing the op-portunities for biotechnology applications inmany areas, including the treatment of dilutehazardous waste. The potential impacts ofthese advancements on waste treatment tech-niques, process modifications, and end-productsubstitutes are discussed here.

Biotechnology has direct application to wastetreatment systems to degrade and/or detoxify


Table 29.Conventional Biological Treatment Methods

Treatment methodAerobic (A)

anaerobic (N) Waste applications LimitationsActivated sludge

Aerated lagoons

Trickling filtersBiocontactorsPacked bed reactorsStabilization ponds

A Aliphatics, aromatics, petrochemicals,steel making, pulp and paper industries

A Soluble organics, pulp and paper,petrochemicals

A Suspended solids, soluble organicsA Soluble organicsA Vitrification and soluble organics

A&N Concentrated organic waste

Anaerobic digestion N Nonaromatic hydrocarbons; high-solids;methane generation

Land farming/spreading A Petrochemicals, refinery waste, sludge

Comporting A Sludges

Volatilization of toxics; sludge disposaland stabilization required

Low efficiency due to anaerobic zones;seasonal variations; requires sludgedisposal

Sludge disposal requiredUsed as secondary treatmentUsed as secondary treatmentInefficient; long retention times, not

applicable to aromatics; sludge removaland disposal required

Long retention times required; inefficienton aromatics

Leaching and runoff occur; seasonalfluctuations; requires long retentiontimes

Volatilization of gases, leaching, runoffoccur; long retention time; disposal ofresiduals

Aerobicrequires presence of oxygen for cell growthAnaerobicrequ!res absence of oxygen for cell growthSOURCE Off Ice of Technology Assessment

Table 30.lndustries With Experience in ApplyingBiotechnology to Waste Management

Industry Effluent stream Major contaminantsSteel

Petroleum refiningOrganic chemical

manufacture

Pharmaceuticalmanufacture

Pulp and paper

Textile

Coke-oven gas scrubbingoperation

Primary distillation processIntermediate organic

chemicals and byproducts

Recovery and purificationsolvent streams

Washing operations

Wash waters, deep discharges

N H3, sulfides, cyanides, phenols

Sludges containing hydrocarbonsPhenols, halogenated hydrocarbons,

polymers, tars, cyanide, sulfatedhydrocarbons, ammoniumcompounds

Alcohols, ketones, benzene, xylene,toluene, organic residues

Phenols, organic sulfur compounds,oils, Iignins, cellulose

Dyes, surfactants, solvents

chemicals.strains can

SOURCE Office of Technology Assessment

Development of new microbial 5. ability to concentrate nondegradable con-be used to improve: stituents.

1. degradation of recalcitrant compounds, Compounds thought to be recalcitrant, (e.g.,2. tolerance of severe or frequently changing toluene, benzene, and halogenated compounds)

operating conditions, have been shown to be biodegradable by iso-3. multicompound destruction, lated strains. Strain improvement in these4. rates of degradation, and species through genetic manipulations has lead


to improved degradation rates. Opportunitiesexist for applications of this technology inremedial situationsi.e., cleanup at spills orabandoned sites.67 The improvement of con-ventional biological systems through the devel-opment of specific microbial strains (super-bugs) capable of degrading multiple com-pounds has been proposed. However, this ap-proach faces engineering difficulties, and de-velopment of collections of organisms work-ing together might be preferable.

Development of biological pretreatment sys-tems for waste streams has some potential forthose wastes that contain one or two recalci-trant compounds. A pretreatment system de-signed to remove a specific toxic compoundcould reduce the shock effects on a conven-tional treatment process. In some cases, a pre-treatment system may be used with other non-biological treatment methods (i.e., incineration)to remove toxic compounds that may not behandled in the primary treatment system or tomake them more readily treated by the primarysystem. In other cases, pretreatment mightrender a waste nonhazardous altogether.

One area of research in advanced plant ge-netics is in the use of plants to accumulatemetals and toxic compounds from contami-nated soils. Current research is direct to fourareas. The first involves use of plants to de-crease the metal content of contaminated soils,through increased rates of metal uptake. Plantsthen could be used to decontaminate soilsthrough concentration of compounds in theplant fiber. The plants then would be harvestedand disposed. The second area of developmentfocuses on direct metal uptake in nonedibleportions of the plant. For example, the develop-ment of a grain crop like wheat that could ac-cumulate metal from soil in the nonusable partsof the plant would allow commercial use ofcontaminated land. A third area of research is

G. T. Thibault and N. W. Elliott, Biological Detoxificationof Hazardous Organic Chemical Spills, in Control of Hazard-ous Material Spills, Conference Proceedings (Nashville, Term.:Vanderbilt University, 1980), pp. 398402.

G. C. Walton and D. Dobbs, Biodegradation of HazardousMaterials in Spill Situations, in Control of Hazardous MaterialSpills Conference Proceedings [Nashville, Term.: VanderbiltUniversity, 1980), pp. 2345.

directed toward development of crops that cantolerate the presence of metal without incorpo-rating these toxic elements in plant tissue. Fi-nally, research is being conducted concerningthe use of plants in a manner similar to micro-organisms to degrade high concentrations ofhazardous constituents.

Changes in process design incorporating ad-vances in biological treatment systems mayresult in less hazardous waste, The develop-ment of organisms capable of degrading specif-ic recalcitrant materials may encourage sourceseparation, treatment, and recycling of processstreams that are now mixed with other wastestreams and disposed. The replacement ofchemical synthesis processes with biologicalprocesses may result in the reduction of haz-ardous waste. Two methods of increasing therate of chemical reactions are through highertemperatures and catalysts. One type of cata-lyst is biological products (enzymes) that inher-ently require milder, less toxic conditions thando other catalytic materials.

Historically, many biological processes (fer-mentations) have been replaced by chemicalsynthesis. Genetic engineering offers oppor-tunities to improve biological process throughreduced side reactions, higher product concen-trations, and more direct routes; thus, geneticengineering offers a means of partially rever-sing this trend. The development of new proc-ess approaches would require new reactor de-signs to take advantage of higher biological re-action rates and concentrations.

Biotechnology also could lead to substitutionof a less or nonhazardous material for a hazard-ous material, particularly in the agriculturalfield. One of the primary thrusts of plant gen-etics is the development of disease-resistantplants, thus reducing the need for commercialproducts such as fungicides. Genetic engineer-ing to introduce nitrogen-fixation capabilitieswithin plants could reduce the use of chemicalfertilizers and potentially reduce hazardouswaste generated in the manufacture of thosechemicals. However, two problems must be re-solved before large-scale applications: 1) thegenetic engineering involved in nitrogen fixa-


tion is complex and not readily achieved, andZ) the overall energy balance of internal nitro-gen-fixation may reduce growth rates and cropyield.

Major Concerns for Biotechnology.Althoughgenetic engineering has some promising appli-cations in the treatment of hazardous wastestreams, several issues need to be addressedprior to widespread commercialization of thetechnology: 8

l

l

l

l

The factors for scale-up from laboratorytests to industrial applications have notbeen completely developed. Limited fieldtests have shown degradation rates in thef ie ld may be much s lower than laboratoryr a t e s w h e r e p u r e c u l t u r e s a r e t e s t e d i np u r e c o m p o u n d s .B a s i c b i o c h e m i c a l d e g r a d a t i o n m e c h a -nisms are not wel l unders tood, The poten-t ia l exis ts for the format ion of o ther haz-ardous compounds th rough smal l envi ron-m e n t a l c h a n g e s o r s y s t e m u p s e t s a n d ,w i t h o u t t h i s b a s i c u n d e r s t a n d i n g , c h e m i -c a l p a t h w a y s c a n n o t b e a n t i c i p a t e d .The potent ia l exis ts for re lease of hazard-o u s c o m p o u n d s i n t o t h e e n v i r o n m e n tthrough incomplete degradat ion or sys temf a i l u r e .There is a possibility of adverse effects re-sulting fro-m the release of engineeredorganisms into the environment.

The potent ia l benef i ts of appl ied genet ics tohazardous was te probably outweigh these fac-tors. Although these factors must be addressed,t h e y s h o u l d m o t i v a t e r a t h e r t h a n o v e r s h a d o wr e s e a r c h i n t h i s a r e a .

Chemical Dechlorination With Resource Recovery.In the late 1970s private efforts were under-taken to find a reagent that would selectivelyattack the carbon-chlorine bond under mildconditions, and thus chemically strip chlorinefrom PCB-type chemicals forming a salt andan inert sludge. Goodyear Tire & Rubber Co.

made public its method, Sunohio and AcurexInc. have developed proprietary reagents, mod-ified the process, and commercialized theirprocesses with mobile units. These processesreduce the concentration of PCB in transform-er oil, which may be 50 to 5,000 parts per mil-lion (ppm) to less than 2 ppm. The SunohioPCBX process is used for direct recycling ofthe transformer oil back into transformers,while the oil from the Acurex process is usedas a clean fuel in boilers.9

Although, the development of these proc-esses was initially aimed at PCB-laden oils ofmoderate concentration (50 to 500 ppm), theirchemistry is generic in that it attacks the car-bon-halogen bonds under mild conditions,Thus, they are potentially applicable to pesti-cides and other halogenated organic wastes aswell as wastes with higher concentrations ofPCBs. The PCBX process has been applied topesticides and other halogenated waste withdetoxification observed, but without publishednumerical results or further developments.10Acurex claims it has commercially treated oilwith a PCB concentration of 7,000 ppm. I ntests performed by Battelle Columbus Labora-t o r i e s f o r A c u r e x , i t s p r o c e s s r e d u c e d d i o x i nconcentration in transformer oil from 380 partsper t r i l l ion (ppt ) to 40 20 ppt . Acurex andt h e E n e r g y P o w e r R e s e a r c h I n s t i t u t e h a v et e s t e d t h e e f f e c t i v e n e s s o f t h e p r o c e s s i n t h el a b o r a t o r y o n c a p a c i t o r s w h i c h c o n t a i n 1 0 0p e r c e n t P C B ( 4 0 t o 5 0 p e r c e n t c h l o r i n e , b yw e i g h t ) . T h e n e x t s t e p i s c o n s t r u c t i o n o f amobi le commercia l -scale faci l i ty which woulds h r e d , b a t c h p r o c e s s , a n d t e s t t h e c a p a c i t o rmaterial .11

The Sunohio (first to have a chemical dechlo-rination process approved by EPA) has fiveunits in operation. Acurex has four mobileunits in operation at this time and at least twoother companies currently market similarchemical PCB destruction services. Acurex,

W. p. pirages, L. M. Curran, and J. S. Hirschhorn, Biotech-nology in Hazardous Waste Management: Major Issues, paperpresented at The Impact of Applied Genetics on Pollution Con-trol symposium sponsored by the University of Notre Dame andHooker Chemical Co., South Bend, Ind., May 24-26, 1982.

@Alternatives to the Land Disposal of Hazardous Wastes, Gov-ernors Office of Appropriate Technology, California, 1981,

Klscar Norman, developer of the PCBX process, personalcommunication, January 1983.

llLeo Weitzman, Acurex Corp., personal communication,January 1983.


Sunohio, and licensees have been selling their As an alternative to incineration, these chem-PCB services for over a year. Acurex and The ical processes offer the advantages of no airFranklin Institute plan to commercialize their emissions, no products of incomplete combus-processes for spill sites involving halogenated tion, reduced transportation risks, and the re-organics. 12 cycling of a valuable material or the recovery

of its fuel value. Further, as with many chem-l=harles Rogers, Office of Research and Development, Indus- ical processes, there is t-he opportunity to di-trial and Environmental Research Laboratory (IERL), Environ-

mental Protection Agency, Cincinnati, Ohio, personal, com- r e c t l y c h e c k t h e d e g r e e o f d e s t r u c t i o n b e f o r e. . . .

munication, January 1983.

Hazard Reduction

Introduction

any product is discharged or used.

Alternatives: Treatment and Disposal

The previous section discussed technologiesto reduce the volume of waste generated. Thissection analyzes technologies that reduce thehazard of waste. These include treatment anddisposal technologies. These two groupingsof technologies contrast distinctly in that itis preferable to permanently reduce risks tohuman health and the environment by wastetreatments that destroy or permanently re-duce the hazardous character of the material,than to rely on long-term containment inland-based disposal structures.

In the United States, as much as 80 percent(by volume) of the hazardous waste generatedis land disposed (see ch. 4). Of these wastes,a significant portion could be treated ratherthan land disposed for greater hazard reduc-tion. In California, for example, wastes whichare toxic, mobile, persistent and bioaccumula-tive comprise about 29 percent of the hazard-ous waste disposed of offsite.13 14

Following a brief summary comparison, thissection reviews over 15 treatment technologies.Many of these eliminate the hazardous char-acter of the waste. Technologies in the nextgroup discussed are disposal alternatives. Theireffectiveness relies on containing the waste toprevent, or to minimize, releases of waste and

WMifbmia Department of Health Services, Initial Statementof Reaaona for Proposed Regulations (R-32 -82), Aug. 18, 1982,p. 23.

WaIifomia Department of Health Services, Current Hazard-ous Waste Generation, Aug. 31, 1982, p. 6.

human and environmental exposure to waste.In this category, the major techniques are land-fills, surface impoundments, and undergroundinjection wells.

This discussion begins with a comparison ofthe treatment and disposal technologies andends with a cost comparison. These discus-sions focus on the competitive aspects of thenumerous hazard reduction technologies.However, choosing among these technical al-ternatives involves consideration of many fac-tors, some of which are neither strictly tech-nical or economic. Choices by waste generatorsand facility operators also depend on Federaland State regulatory programs already in place,those planned for the future, and on percep-tions by firms and individuals of existing regu-latory burdens may exist for a specific waste,technology, and location.

Summary Comparison

For the purpose of an overview, qualitativecomparisons among technologies can be made.Based on principle considerations relevantacross all technologies, the diverse range ofhazard reduction technologies can be com-pared as presented in table 31. The table sum-marizes the important aspects of the aboveissues for each generic grouping of technol-ogies included. Individual technologies areconsidered in more detail in the following dis-cussions on treatment and disposal technol-ogies. For simplicity, the technologies aregrouped generically, and only a limited number


Table 31 .Comparison of Some Hazard Reduction Technologies

DisposalLandfills and

Impoundments Injection wellsEffectiveness How well It Low for volatiles, High, based on theory,

contains or destroys questionable for Iiquids but limited field datahazardous based on lab and field availablecharacteristics tests

Reliability issues: Siting, construction, and Site history and geology,operation well depth, construction

Uncertainities Iong-term and operationintegrity of cells andcover, Iiner life lessthan life of toxic waste

Envirornmental media Surface and ground water Surface and ground watermost affected

Least compatible Liner reactive, highly toxic, Reactive, corrosive,waste: b mobile, persistent, highly toxic, mobile,

and bioaccumulative and persistentCosts LO W, M o d , H i g h L-M LResource recovery

potential None Nonea Molte s t ,n al high.temperature fluid wall, and plasma arc treatments

Incineration and otherthermal destruction

High, based on field tests,except little data onspecific constituents

Long experience withdesign

Monitoring uncertaintieswith respect to highdegree of DRE,surrogate measures,PICs, incinerability

Air

Highly toxic and refractoryorganics, high heavymetals concentration

M-H (Coincin = L)

Energy and some acids

TreatmentEmerging -

high.temperaturedecomposition a

Very high, commercialscale tests

Limited experienceMobile units, onsite

treatment avoidshauling risks

Operational simplicity

Air

Possibly none

M-H

Chemical stabilizationHigh for many metals,

based on lab tests

Some inorganics stillsoluble

Uncertain Ieachate test,surrogate for weathering

None Iikely

Organics

M

Energy and some metals Possible building material .

bWaste for which this method may be less effective for reducing exposure, relative to other technologies Waste listed do not necessarily denote common usageSOURCE Office of Technology Assessment

of groups are compared, The principal consid-erations used for comparison are the following:

Effectiveness.This does not refer to theintended end result of human health andenvironmental protection, but to the capa-bility of a technology to meet its specifictechnical objective. For example, the effec-tiveness of chemical dechlorination is de-termined by how completely chlorine is re-moved. In contrast, the effectiveness oflandfills is determined by the extent towhich containment or isolation is achieved.Reliability .This is the consistency overtime with which a technologys objectiveis met, Evaluation of reliability requiresconsideration of available data based ontheory, laboratory-scale studies, and com-mercial experience.

A prominent factor affecting the relativereliability of a technology is the adequacyof substitute performance measures. Veri-fication that a process is performing as de-signed is not always possible and, whenpossible, verification to a high level of con-fidence may require days or weeks to com-plete and may not be useful for timely ad-justments. In some cases, key process vari-ables can be used as substitute measuresfor the effectiveness of the technology.Substitute measures are used either be-

cause they provide faster and/or cheaperperformance information, A disadvantageof surrogate measures is that there may notbe reliable correlation between the surro-gate measurement and the nature of anyreleases to the environment.

The reliability of a technology shouldalso be judged on the degree of processand discharge control available. This re-fers to the ability to: 1) maintain properoperating conditions for the process, and2) correct undesirable releases. Processcontrol requires that information aboutperformance be fed back to correct theprocess. Control systems vary categorical-ly with respect to two important time vari-ables:

1. the length of time required for infor-mation to be fed back into the system(e.g., time for surrogate sampling andanalysis, plus time for corrective ad-justments to have the desired effect);and

2. the length of time for release of dam-aging amounts of insufficiently treatedmaterials in the event of a treatmentupset.

In the case of landfills, once ground watermonitoring has detected a leak, damagingdischarges could have already occurred.


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If detection systems are embedded in theliner, then detection of a system failure isquicker and more reliable, and it offersmore opportunity for correction. Landfill-ing and incineration are examples wherethese time factors are important. In con-trast, batch treatment processes, as dis-cussed in the preceding section on WasteReduction, offer the distinct opportunityto contain and check any release, and re-treat it if needed, so that actual releasesof hazardous constituents are prevented.Other chemical and biological treatmentsare flow-through processes, with differentrates of flow-through. These treatmentsvary in their opportunity for discharge cor-rection. Generally, processes used in wastesegregation and recycling offer this kindof reliability.Environmental media most affected.This refers to the environmental mediacontaminated in the event that the technol-ogy fails.Least compatible waste.Some technol-ogies are more effective than others in pre-venting releases of hazardous constituentswhen applied to particular types of waste.Costs.Costs vary more widely amonggeneric groups of technologies than withinthese groups. Table 31 presents general-ized relative costs among these groups.The final section of this chapter gives someunit management cost details.Resource recovery potential.Treatmentsthat detoxify and recover materials for re-cycling are discussed under Waste Re-duction. However, some materials, aswell as energy, can be recovered withsome of the technologies reviewed in thissection. To the extent that materials andfuels are recovered and used, the genera-tion of other hazardous wastes maybe re-duced. Potential releases of hazardousconstituents from recovery and recyclingoperations must also be considered,

Treatment Technologies

In this section, treatment technologies refersto those techniques which decompose or break

down the hazardous wastes into nonhazardousconstituents. * Most of these treatments usehigh temperatures to decompose waste. Someof the promising emerging technologies causedecomposition by high-energy radiation and/orelectron bombardment. There are several im-portant attributes of high-temperature destruc-tion technologies which make them attractivefor

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hazardous waste management:

the hazard reduction achieved is perma-nent;they are broadly applicable to wastemixes; most organics, for example, maybe converted into nonhazardous combus-tion products; andthe volume of waste that must ultimatelybe land disposed is greatly reduced, -

In addition, with some of these treatments,there is a possibility of recovering energy and/or materials.** However, potential recovery ofenergy and materials is not the primary focusof this discussion.

Incineration is the predominant treatmenttechnology used to decompose waste. The termincineration has been given a specific mean-ing in Federal regulations, where it denotes aparticular subclass of thermal treatments, anddraft Federal regulations may give specificmeaning to the additional terms industrialboiler and industrial furnace. Although theFederal definitions affect the manner in whicha facility is regulated, unless specifically noted,

l Treatments can also be used to segregate specific waste con-stituents, or to mitigate their characteristics of ignitability, cor-rosiveness, or reactivity. Most of these are referred to as indus-trial unit processes, and their use is usually embedded in largertreatment schemes. A lengthy listing will not be reproduced here.Many were described in the preceding section on Waste Reduc-tion Technologies. The interested reader is also referred to anyindustrial unit operations manual. Another source is Chemical,Physical, Biological (CPB) Treatment of Hazardous Wastes, Ed-ward J. Martin, Timothy Oppelt, and Benjamin Smith, Officeof Solid Waste, U.S. Environmental Protection Agency, pre-sented at the Fifth United States-Japan Governmental Conferenceof Solid Waste Management, Tokyo, Japan, Sept. 28, 1982.

l *For example, the Chemical Manufacturers Associationclaims that a significant portion of the hydrochloric acid pro-duced in the United States and some sulfuric acid come fromincineration of chlorinated organics through wet-scrubbing ofthe stack gases. (CMA, personal communication, December1982.) Also, there is clear potential for metals recovery with theemerging high-temperature technologies.

Ch. 5Technologies for Hazardous Waste Management l 159

combustion or incineration are used inthis report to refer to the generic processes ofinterest, and do not necessarily mean specificfacility designs or regulatory categories.

Applicable Wastes

Liquid wastes are generally more easily in-cinerated than sludge or waste in granularform, because they can be injected easily intothe combustion chamber in a manner whichenhances mixing and turbulence. Wastes withheterogeneous physical characteristics andcontainerized or drummed wastes are difficultto feed into a combustion chamber. The rotarykiln is designed for sludge-like, granular andsome containerized waste. Recently, a newfirm has emerged (Continental Fibre Drum)which manufactures combustible fiber drumsfor waste containers. These fiber drums of or-ganic waste can be incinerated in speciallydesigned rotary kilns.

Elemental metals, of course, cannot be de-graded. Waste which contain excessive levelsof volatile metals may not be suitable for incin-eration. Under the high-temperature conditionsin an incinerator, some metals are volatilizedor carried out on particulate. Oxides of metalscan generally be collected electrostatically.However, some volatilized forms cannot beelectrically charged, resisting electrostaticalcollection. These include metallic mercury,arsenic, antimony, and cadmium, and verysmall particles.15 (Particles having insufficientsurface area also cant be adequately chargedand collected, ) Wet second-stage electrostaticprecipitators are designed for removing theseforms of volatized metals, but they are expen-sive and not in widespread use. High-pressuredrop-emission controllers have also been effec-tive, but their use is declining.

Technical Issues

There are approximately 350 liquid injectionand rotary kiln incinerators currently in ser-vice for hazardous waste destruction.18 Most

15Frank Whitmore, Versar, inc., persona} communication,August 1982.

Gene Crumpler, Office of Solid Waste, Hazardous and Indus-trial Waste Division, Environmental Protection Agency, personalcommunication, January 1983.

of these facilities may eventually be permittedas RCRA hazardous waste incinerators. A fargreater, although unknown, number of facili-ties may be combusting hazardous waste prin-cipally in order to recover their heating value.Under current regulations, these facilitieswould not be permitted as hazardous wasteincinerators. Under future regulations theymay become subject to performance standardssimilar to those in effect for incinerators, beprohibited from burning certain types of ignit-able hazardous waste, or be subject to some in-termediate level of regulation.

To regulate incinerators, EPA has decidedto use performance standards rather thanspecification of design standards. The currentregulations specify three performance stand-ards for hazardous waste incineration. 18 Thesestandards are described below:

1.

2.

3.

A 99.99 percent destruction and removalefficiency (DRE) standard for each prin-cipal organic hazardous constituent(POHC) designated in the waste feed. (Thisis the most difficult part of the standardto meet.) The DRE is calculated by the fol-lowing mass balance formula:

DRE = (1 Wout/Win) X 100 percent,where:

Win = the mass feed rate of 1 POHCin the waste stream going into theincinerator, and

Wout = the mass-emission rate of thesame POHC in the exhaust prior torelease to the atmosphere.

Incinerators that emit more than 4 lb ofhydrogen chloride per hour must achievea removal efficiency of at least 99 percent.(All commercial scrubbers tested by EPAhave met this performance requirement.)Incinerators cannot emit more than 180milligrams (mg) of particulate matter perdry standard cubic meter of stack gas. Thisstandard is intended to control the emis-sions of metals carried out in the exhaustgas on particulate matter. (Recent tests in-dicate that this standard may be more diffi-cult to achieve than was earlier thought.19)

Ibid.1840 CFR, Sec. 264.343.19Wrumpler, op. cit.


There are instances in which the incineratorperformance standards do not fully apply.First, the regulations do not apply to facilitiesthat burn waste primarily for its fuel value. Todate, energy recovery of the heat value of wastestreams qualifies for the regulatory exemp-tion.20 Second, facilities burning waste that areconsidered hazardous because of characteris-tics of ignitability, corrosiveness, and reactivityare eligible for exemptions from the perform-ance standards. Of the three, the exemption forenergy recovery applies to a greater volume ofhazardous waste. Finally, incinerators operat-ing at sea are not governed by RCRA butrather by the Marine Protection, Research, andSanctuaries Act of 1972. Regulations under thisact do not require scrubbing of the incineratorexhaust gas. In the future, EPA may requirethat incinerator ships operating in close prox-imity to each other scrub their exhaust gases.

With regard to combustion processes, themost important design characteristics are thethree Ts:

1. maintenance of adequate temperatureswithin the chamber,

2. adequate turbulence (mixing) of wastefeed and fuel with oxygen to assure evenand complete combustion, and

3. adequate residence times in the high-tem-perature zones to allow volatilization ofthe waste materials and reaction to com-pletion of these gases.

Finally, the DRE capability of these technol-ogies generally varies widely depending on thewaste type to which it is applied, Chlorine orother halogens in the waste tend to extinguishcombustion; so, in general, these wastes tendto be more difficult to destroy. An importantrelated misconception is that the more toxiccompounds are the more difficult they are toburn. Toxic dioxins and PCBs are popular ex-amples of highly halogenated wastes which areboth highly toxic and difficult to destroy, butthese should not imply a rule. Discussion ofwaste incinerability is included below.

2040 CFR, sec. 261.2 (c)(2].

Waste treatments with reliable high-destruc-tion efficiencies offer attractive alternatives toland disposal for mobile, toxic, persistent, andbioaccumulative wastes. However, these treat-ment technologies are not free of technicalissues. The first three issues noted below relatedirectly to policy and regulation, and the re-maining three issues summarize sources oftechnical uncertainty with respect to the verysmall concentrations of remaining substances.Improvements in policy and regulatory controlshould recognize these technical issues:

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Significant sources of toxic combustionproducts, emitted to the air, are not beingcontrolled with the same rigor as areRCRA incinerators. These include emis-sions from facilities inside the propertyboundaries of refineries and other chem-ical processing plant sites. In addition,boilers can receive and burn any ignit-able hazardous waste which has beneficialfuel value (see discussion on Boilers).Draft regulations governing boilers arecurrently being developed under RCRAand very limited reporting requirementsare brand new. Under the Clean Air Act,there is only very limited implementationgoverning the remaining facilities. Stand-ards have been set for only four sub-stances, and apply to only a small class offacilities.There are some problems with the tech-nology-based DRE performance stand-ards. EPA uses the technology-based per-formance standard for practicality, andfor its technology-forcing potential. How-ever, the performance standard overly sim-plifies the environmental comparisonsamong alternatives.

Complete knowledge about the trans-port, fate, and toxic effects of each wastecompound from each facility is unobtain-able. Thus, some simplified regulatory toolis needed. However, the most importantand known factors should be included inregulatory decisions. Notably, these couldinclude: the toxicity of the waste, the loadto the facility (the waste feed concentra-


tion and size of the facility), and popula-tion potentially affected. Future regula-tions, however, could endeavor to shapethe manner in which competing technol-ogies are chosen in a more environmental-ly meaningful way (see ch. 6),

Finally, the 99.99 percent DRE may beviewed as a forcing standard with re-spect to some high-temperature technolo-gies, but emerging high-temperature tech-nologies (notably plasma arc) may offermuch greater and more reliable DREs.Rather than forcing, it may discourage thewid

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