Process Engineering for Pollution Control and Waste Minimization_12 pot

Gonzales Los Alamos National Laboratory, Los Alamos, New Mexico and New Mexico State University, Las Cruces, New Mexico 1 INTRODUCTION Ecological risk assessment is defined as “the quali

material and energy balances many be found in a number of chemical engineeringtexts, such as Felder and Rousseau (4) and others.

3 ADDITION OF CHEMODYNAMICS

In order to take LCA beyond its usual scope to assess a waste site remedy, weneed not only to include the mass and energy balances for environmentalcompartments, but also the models and mechanisms of inter- and intramediatransport The concepts and models of chemodynamics are provided in significantdetail by Thibodeaux (5), and by Reible and Choi (6) For the purposes of thisdiscussion, it is assumed that appropriate models of the fate and transport ofcontaminants for a case are known, estimated, or available in some fashion Sincethe objective of the LCA in remediation is to assess the burden being placed onthe environment by various remedies, the application of realistic and appropriatemodels is essential and found in references above (5,6) for certain cases

applied to this integrated management methodology for comparison to the firstattempt Thus, methods can be evaluated for risk-based remediation or manufac-turing as in LCA for the most economical approach It should be noted here thattechnology is on a moving time line, and what is successful and economical todaywill need to be reassessed several times in the future as chemical fate andtransport modeling, our understanding of the environment, technologies, andregulations all change In this manner, “new” technologies such as monitorednatural attenuation (MNA) can be assessed alongside and with active remedies asdescribed in the example below.

5 EXAMPLE OF ASSESSMENT

The Petro Processors, Inc (PPI), site is one of the most significant Superfund sites

in the United States While it is not directly under Superfund, due to agreementamong the parties and existing consent decree in the U.S District Court, MiddleDistrict of LA, it provides an excellent example, via hindsight, of the utility ofLCA for risk-based remediation methodology as described by Constant et al (8).Details of the site(s), being named Brooklawn and Scenic, for the nearbyroadways, may be found at EPA’s Region VI Web site (9), and are not describedhere The site(s) contain approximately 400,000 tons of chlorinated hydrocarbonwastes, including hexachlorobenzene, hexachlorobutadiene, TCE, DCE, lowerchlorinated products, and numerous other petrochemical wastes of similar nature.The mixture forms a dense, nonaqueous, viscous phase, which is currentlycovered and maintained by hydraulic containment of the groundwater and recov-ery of the organic phase (both of which are treated on-site) under strict regulatoryrequirements Louisiana State University (LSU) has served as the Court’s Expertfor the last 10 years regarding cleanup of this site, with the role being researchinto advanced technologies and assisting the court in monitoring and assessingthe remediation

Just prior to LSU’s involvement, the remedy was to remove the waste,stabilize the material, and place it in a lined 1 × 106 yd3 vault, with somehydraulic containment and recovery of site areas found difficult to remove due tothe high water table However, due to volatile emissions exceeding fence-linelimits, the removal method was abandoned The next remedy to be put in placewas active hydraulic containment (expansion of the previous pumping layout),with several hundred wells to remove organics and contaminated water over thelong term in order to protect the underlying aquifer and prevent migration Todate, only about 1% of the free-phase material has been removed, but containmentappears successful, at the expense of treating millions of gallons of watercontaining only trace contamination levels As this pumping method was beinginstalled at Brooklawn, via ongoing research by LSU and site personnel for

augmentation of the pumping operation by both passive and active technologies,intrinsic biodegradation and hence natural attenuation was studied and thenincorporated into the remedy The addition of biodegradation, sorption, disper-sion, etc as required within the lines of evidence of MNA as presented by EPA(10), has had a significant impact on the remedy of the PPI site.

It appears at this time that active pumping of significant water volumes may

be greatly reduced, while still focusing on source removal (NAPL), with theunderstanding that significant residuals remain bound in these systems The MNAcomponent is proposed to contain and reduce the size of contaminated ground-water over time, with acceptable risk Thus, using the same receptors and riskissues, incorporation of MNA into the PPI remedy promises to reduce signifi-cantly the cost of the remedy, without increasing eco- or human health risk In arecent comparison, starting with the same source and endpoints, in the same timeframe, MNA with limited hydraulic containment (a few source removal wells)was evaluated against active hydraulic containment and recovery (many pumpingwells across the site) for the Scenic site of PPI This assessment includedmonitoring and other costs associated with these technologies, and a 70% costsavings was found by incorporation of MNA into the remedy This was duemainly to the reduced number of wells to be installed and the significant reduction

in treatment of produced water While this example case of remedy comparisonhas occurred during the remediation of PPI, it clearly shows that we have the tools

of LCA, risk-based remediation, and MNA at our disposal When properlyintegrated, one can provide acceptable waste management schemes prior toinitiation of a manufacturing project or site remediation However, as technologychanges, as stated earlier, this assessment must be ongoing

REFERENCES

1 T E Graedel, Streamlined Life-Cycle Assessment, pp 97–98 Englewood Cliffs, NJ:

Prentice Hall, 1998.

2 P C Schulze (ed.), Measures of Environmental Performance and Ecosystem

Condi-tion Washington, DC: National Academy Press, 1999.

3 R J Walter, Practical Compliance with the EPA Risk Management Program New

York: Center for Chemical Process Safety of the AIChE, 1999.

4 R M Felder and R W Rousseau, Elementary Principles of Chemical Processes,

pp 81–86 New York: Wiley, 1978.

5 L J Thibodeaux, Chemodynamics: Environmental Movement of Chemicals in Air,

Water and Soil New York: Wiley, 1979.

6 B Choy and D D Reible, Diffusion Models of Environmental Transport Boca

Raton, FL: Lewis Pub., CRC Press, 2000.

7 S T Hwang J Environ Sci Health, A, vol A27, no 3, pp 843–861, 1992.

8 W D Constant, L J Thibodeaux, and A R Machen, Environmental Chemical

Engineering: Part I—Fluxion; Part II—Pathways Trends Chem Eng., vol 2,

pp 525–542, 1994.

9 U.S Environmental Protection Agency (EPA) Region VI Website, Information on Superfund sites, Louisiana, Petro Processors, Inc., http://www.epa.gov/earth1r6/ 6sf/6sf-la.htm.

10 Robert S Kerr Environmental Research Center (U.S EPA), Natural attenuation short course materials, Ada, OK, December 2–4, 1997.

Risk-Based Pollution Control and

Waste Minimization Concepts

Gilbert J Gonzales

Los Alamos National Laboratory, Los Alamos, New Mexico and

New Mexico State University, Las Cruces, New Mexico

1 INTRODUCTION

Ecological risk assessment is defined as “the qualitative or quantitative appraisal

of impact, potential or real, of one or more stressors (such as pollution) on flora,fauna, or the encompassing ecosystem.” The underlying principles behind riskreduction and integrated decision making that are detailed in U.S EnvironmentalProtection Agency (EPA) strategic initiatives and guiding principles includepollution prevention (1) Pollution control (PC) and waste minimization (WM)are probably the most effective means of reducing risk to humans and theenvironment from hazardous and radioactive waste Pollution control can bedefined as any activity that reduces the release to the environment of substancesthat can cause adverse effects to humans or other biological organisms Thisincludes pollution prevention and waste minimization Waste minimization isdefined as pollution prevention measures that reduce Resource Conservation andRecovery Act (RCRA) hazardous waste (2) Reduced risk is one benefit of thesepractices, and it results most directly from lower concentrations of contaminantsentering the environment from both planned and accidental releases

Although it is difficult to quantify the reductions in the release of inants to the environment that have resulted from reductions in waste, thereductions have most assuredly reduced risk to humans and the environmentposed by toxicants Using examples from Los Alamos National Laboratory(LANL), we will discuss the interrelatedness of pollution prevention/waste min-imization with risk reduction and how risk assessment can be generally applied

contam-to the field of pollution prevention and waste minimization While emphasis inthis chapter is on “ecological risk assessment,” the concepts and principles canalso be applied to human health risk assessment For purposes of this chapter,distinction is not made between pollution prevention, waste minimization, re-cycling or other waste management techniques, and other related terms Rather,emphasis is on source reduction, which includes any practice that reduces theamount of contaminant entering a waste stream or the environment

It is evident that the EPA’s hierarchy of general pollution prevention andwaste minimization methods is implicitly related to risk reduction (2) Thepreferred method, source reduction, results in the greatest reduction in human andecological risk from contaminants Source reduction is followed in effectiveness

by recycling, treatment, and disposal While it is possible, depending on thetechnology used, that recycling and treatment may increase risk to worker healthbecause of increases in contact handling of waste, the prioritized list (sourcereduction → recycling → treatment → disposal) generally results in a decrease

in risk to the public and the environment as one progresses from the leastpreferred to the most preferred method The reason for this is simple Thepreferred method results in little, if any, release of contaminants into the environ-ment compared to the less preferred methods; with the less preferred methods,not only does the quantity of contaminants potentially released into the environ-ment increase, the potential to release them increases With this premise, it is thenimportant to realize the magnitude of risk reduction achieved by employingpollution prevention and waste minimization at facilities such as LANL

2 SITE DESCRIPTION AND CHARACTERIZATION

LANL is located in north-central New Mexico, approximately 60 miles northwest

of Santa Fe (Figure 1) LANL is a U.S Department of Energy-owned complexmanaged by the University of California that was founded in 1943 as part of theManhattan Project to create the first nuclear weapon Since then, LANL’s mission

to design, develop, and test nuclear weapons has expanded to other areas ofnuclear science and energy research

The Laboratory comprises dozens of individual technical areas located on

43 square miles of land area; about 1400 major buildings and other facilities arepart of the Laboratory The Laboratory is situated on the Pajarito Plateau, whichconsists of a series of fingerlike mesas separated by deep east-to-west–oriented

RIO ARRIBA COUNTY SANTA FE COUNTY

VAL CO.

SANDO-SANDOVAL COUNTY LOS ALAMOS COUNTY

SANDOVAL COUNTY

WHITE

SANTA FE NATIONAL FOREST S

AN

TAF

To Santa Fe

LOS ALAMOS COUNTY

RIO ARRIBA COUNTY

TAOS COUNTY

SANDOVAL

FE COUNTY BERNALILLO COUNTY

LOS ALAMOS COUNTY

Pajarito R oad East Jemez Road

Technical Area boundaries County boundaries Other political boundaries Major paved roads

ROCK

NM

CO UT

AZ

TX OK

canyons cut by intermittent streams (Figure 2) Mesa tops range in elevation fromapproximately 7800 ft on the flanks of the Jemez Mountains to about 6200 ft attheir eastern termination above the Rio Grande.

Researchers at Los Alamos work on initiatives related to the Laboratory’scentral mission of enhancing global security as well as on basic research in avariety of disciplines related to advanced and nuclear materials research, devel-opment, and applications; experimental science and engineering; and theory,modeling, analysis, and computation As a fully functional institution, LANL alsoengages in a number of related activities including waste management; infrastruc-ture and central services; facility maintenance and refurbishment; environmental,

FIGURE 2 Overhead view of the topography in and around the Los Alamos National Laboratory.

ecological, cultural, and natural resource management; and environmental ration, including decontamination and decommissioning As result of the scien-tific and technical work conducted at Los Alamos, the Laboratory generates,treats, and stores hazardous, mixed, and radioactive wastes.

resto-About 2120 contaminant potential release sites (PRSs) have been identified

at LANL The LANL PRSs are diverse and include past material disposal areas(landfills), canyons, drain lines, firing sites, outfalls, and other random sites such

as spill locations Categorizing contaminants into three types—organics, metals,and radionuclides—Los Alamos has all three present The contaminants includevolatile and semivolatile organics, polychlorinated biphenyls (PCBs), asbestos,pesticides, herbicides, heavy metals, beryllium, radionuclides, petroleum prod-ucts, and high explosives (3) The primary mechanisms for potential contaminantrelease from the site is surface-water runoff carrying potentially contaminatedsediments and soil erosion exposing buried contaminants The main pathways bywhich released contaminants can reach off-site residents are through infiltrationinto alluvial aquifers, airborne dispersion of particulate matter, and sedimentmigration from surface-water runoff Like many other sites, the predominantpathway by which contaminants enter terrestrial biological systems is the inges-tion of soil, intentional or not

Diverse topography, ecology, and other factors make the consideration ofissues related to contamination in the LANL environment complex “Since 1990,LANL’s environmental restoration project has conducted over 100 cleanups Theenvironmental restoration project has also decommissioned over 30 structures andconducted three RCRA closure actions during this period Schedules have beenpublished for the planned cleanup of approximately 700 to 750 additional sites.This schedule encompasses a period of about 10 years, beginning with fiscal year

1998 The number of cleanups per year varies from approximately 100 in fiscalyear 2002 to 18 in fiscal year 2008 An important and integral part of thispollution prevention technology and of identifying interim protection measures isecological risk assessment” (3)

3 POLLUTION PREVENTION AND WASTE MINIMIZATION

AT LANL

The pollution prevention program at the Laboratory has been successful inreducing overall LANL wastes requiring disposal by 30% over the last 5 years.The program is site wide but has facility-specific components, especially for thelarger generators of radioactive and hazardous chemical wastes Past reductionsindicate that waste generation in the future should be less than that projected TheSite Pollution Prevention Plan for Los Alamos National Laboratory (4) describesthe LANL Pollution Prevention and Waste Minimization Programs, including ageneral program description, recently implemented actions, specific volume

reductions resulting from recent actions, and current development/demonstrationefforts that have not yet been implemented.

More specifically, LANL has achieved reductions in the generation ofhazardous waste, low-level radioactive waste (LLW), and mixed LLW These andtwo other waste types are defined as follows:

Hazardous waste—Any substance containing waste that is regulated byRCRA, the Toxic Substances Control Act, and New Mexico as a SpecialWaste

Low-level radioactive waste (LLW)—Radionuclide-containing substanceswith a radionuclide activity (sometimes referred to as concentration) ofless than 100 nCi/g

Mixed LLW—Substances containing both RCRA constituents and LLW.Transuranic radioactive (TRU) waste—Radionuclide-containing substanceswith a radionuclide activity (concentration) equal to or greater than

100 nCi/g

Mixed TRU waste—Substances containing both RCRA and TRU waste.Estimated reduction rates of chronically generated waste, by waste type,over a 6-year period are (D Wilburn, personal communication, 2000)

Hazardous waste: 11%/yr (65% from 1993 to 1999)LLW: 11%/yr (67% from 1993 to 1999)

Mixed LLW: 12%/yr (72% from 1993 to 1999)Production of TRU and mixed TRU waste combined has increased by anaverage of 38%/yr (228% from 1993 to 1999)

The Laboratory has dozens of pollution prevention projects ongoing andplanned Some of the efforts are pollution prevention and waste minimization inthe strictest sense and some (e.g., separation of waste types or satellite treatmentfollowed by centralized treatment) are pollution control in the broadest sense,including efforts where cost savings is the primary goal and pollution control is

a secondary benefit Three examples of pollution control/waste minimization atLANL follow

Generator Set-Aside Fee-Funded (GSAF) Plutonium Ingot Storage Cubicle Project “An aliquot casting and blending technique is under imple-

mentation at LANLs Plutonium Facility The aliquot process allowsout-of-specification plutonium to be blended with other plutonium so thatthe final mixed batch meets specifications and is uniform This avoidsthe cost and waste generation related to reprocessing out-of-specificationplutonium ingots through the nitric acid line In addition the moreuniform product will reduce the reject rate and will avoid reprocessingand remanufacturing wastes This project will fabricate a storage system

with 20 cubicles It is expected that 12.5 m3 of TRU waste can be avoidedover the 25 year life of the cubicle system This project has an estimated100% return on investment when prior investments are included in thebase project cost This project is the final step necessary to achievealiquot blending The GSAF program is funding purchase of the storagecubicle and the operating group has programmatic support for installingand qualifying the cubicle.”

GSAF Reduction of Acid Waste and Emissions “The Laboratory’s

Analyti-cal Chemistry Sciences Group’s performance of analytiAnalyti-cal services at one

of the Laboratory’s technical areas requires the dissolution of up to20,000 samples per year The current process is hot plate digestion whichrequires large quantities of chemicals, mostly acids, and results in thevolatilization and release to the atmosphere of 90% of those chemicals.The yearly consumption of HNO3, HCl, HF, HClO4 and NH4OH isestimated to be 3395 kgs About 3095 kgs of these chemicals arevolatilized and become air emissions from the stacks; the balance isdiluted and discharged to the Laboratory’s Radioactive Liquid WasteTreatment Facility via the LLW acid line The stack emissions constituteabout 30% of the Laboratory’s annual hazardous air pollutant discharges

By switching to a microwave and muffle furnace oven process, annualconsumption of the chemicals listed above can be reduced to about 370kgs, an 89% reduction It is estimated that implementing the new processwill reduce the Laboratory’s hazardous air pollution discharges by threetons The estimated return on investment for this project is 82%.”

Waste Minimization and Microconcentric Nebulization for Inductively pled Plasma-Atomic Emission Spectroscopy “One of the most popular

Cou-techniques for multi-element analysis is inductively coupled plasmaatomic emission spectroscopy (ICP-AES) The most common method ofintroducing samples into the ICP torch is pneumatic nebulization Thestandard nebulizers, in conjunction with typical spray chambers, exhibitvery low transport efficiency Because of this inefficiency the ICP-AESgenerates almost a liter per day of rinse water that consists primarily ofdilute nitric acid mixed with other contaminants The other contaminantscan be TRU waste, LLW, mixed LLW or hazardous waste depending onthe samples analyzed Under this project an existing microconcentricnebulizer will be deployed with the ICP-AES and optimized for analysis

of trace elements in a variety of plutonium-containing matrices It isexpected that using an optimized microconcentric nebulizer will reducethe daily rinse water from the spray chamber drain to about 50 ml Thisrepresents a 95% or 200 l/yr reduction in the volume of waste requiringdisposal A 50 liter per year reduction in LLW plastic sample containers

is expected Reducing the volume of samples in the glovebox will

simplify the ICP-AES operation, reducing various risk parameters Thereturn on investment ranges from 10–50%.”

4 ECOLOGICAL RISK ASSESSMENT

Ecological risk assessment is defined as “the qualitative or quantitative appraisal

of impact, potential or real, of one or more stressors (such as pollution) on flora,fauna, or the encompassing ecosystem.” The Laboratory is employing the EPA’siterative and tiered approach to ecological risk assessment whereby less complexassessments with greater conservatism and uncertainty are employed first, fol-lowed by the advancement of potential problem areas and contaminants toprogressively more complex and realistic assessments with lower uncertainty Thepurpose of this section is not to present ecological risk assessment methods, asthere are many excellent sources on this subject (5–8) Rather, the purpose is tointroduce concepts in ecological risk assessment that could be considered indesigning pollution control and waste minimization programs

4.1 History at the Los Alamos National Laboratory

Ecological risk assessment (“ecorisk”) at the Laboratory is a work in progress.Methods for ecorisk screening and “tier 2” assessments have been in developmentand implementation since approximately 1993 Most screenings and assessmentscompleted at the Laboratory thus far are based on the U.S EPA hazard quotientmethod, whereby hazard quotient values are calculated for receptors for eachcontaminant by area and may be thought of as a ratio of a receptor’s exposure atthe site to a safe limit or benchmark:

HQij is the hazard quotient for receptor I to COPC jexposureij is the dose to receptor i for COPC jsafe limit is an effects or no effects level, such as a chronic no-observed-adverse-effects level (NOAEL)

4.1.1 Screening

In 1995 a very conservative method for screening contaminants and contaminatedareas was developed (9) The method involved the selection of ecologicalendpoints that focused on animal feeding guilds, a listing of candidate contami-nants, exposure/dose–response estimation, estimation of food and soil ingestion,and risk characterization A comparison value or safe limit was based on foragingmode, behaviors, types of food consumed, the amount consumed, and NOAELs

or radiation dose limits when available The safe limits for radionuclides werelargely laboratory-derived rat-based values used in human risk assessments

As such, this and the use of other conservative factors or assumptions resulted in

a method that likely overestimated potential risk by orders of magnitude, cially for radionuclides At least one application of the method is known to haveoccurred (10)

espe-Currently at LANL, ecorisk screening encompasses qualitative “scopingevaluation” as the basis of problem formulation and “screening evaluation” toidentify contaminants of potential concern (COPCs) by exposure media Thescreening evaluation focuses on identifying sites that require further investigationand risk characterization (11) A key component to the screening evaluation, andone of interest to PC/WM, is the ecological screening level (ESL) concept AnESL is basically a contaminant safe limit, or acceptable effects level, below whichmeasurable effects are not expected ESLs are most useful in units of contaminantamount per quantity of soil, so that measurements of contaminant levels in soilcan be quickly and directly compared The ESLs are developed for each ecolog-ical receptor of interest, each chemical, and are media specific They are deter-mined so that if an area has levels of a chemical above the ESL in any medium,then the area is deemed to pose a potentially unacceptable risk to ecologicalreceptors Calculations of ESLs require toxicity information, including toxicityreference values (TRVs), preferably chronic NOAELs, and knowledge of transfercoefficients including bioconcentration and bioaccumulation factors Details onthis information and on the process for calculating and selecting ESLs aredocumented in a LANL report (11); however a summary is provided here

Nonradionuclides. “Although soil ESLs are based on exposure of trial receptors—plants, invertebrates (earthworms), and wildlife—they are deter-mined differently for each receptor The different approaches are required because

terres-of the different ways that toxicological experiments are performed for theseorganisms For plants, earthworms and other soil-dwelling invertebrates, effectsare based on the concentration of a COPC in soil Therefore, ESL values aredirectly based on effects concentrations and modeling is not required For plantsand invertebrates the soil ESL was ‘back-calculated’ from No-Observed-Effect-Concentrations Exposure to wildlife, however, is dependent on exposure of theorganism to a chemical constituent from a given medium (such as soil or