United States
Environmental Protection
Office of Research and
Washington, DC 20460
April 1992
Eighteenth Annual
Risk Reduction Engineering
Laboratory Research
Abstract Proceedings


                                            April 1992
                      Eighteenth Annual
Risk Reduction Engineering Laboratory Research Symposium
                        Abstract Proceedings
       Sponsored by the U.S. EPA, Office of Research and Development
                  Risk Reduction Engineering Laboratory
                          Coordinated by:

              Science Applications International Corporation
                      Ft. Washington, PA  19034
                         Project Officers:

                           Gordon Evans
                         Emma Lou George
                      CINCINNATI, OH 45268
                                                        Printed on Recycled Paper

      These Proceedings  have been reviewed in accordance  with the U.S. Environmental
Protection Agency's peer and administrative; review policies and approved for presentation and
publication.  Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.              i

       Today's rapidly developing technologies and industrial practices frequently carry with
them the increased generation  of materials, that  if improperly dealt with, can threaten both
public health and the environment. The U. S. Environmental Protection Agency is charged by
Congress with protecting the Nation's land, air,  and water resources.  Under a mandate of
national environmental laws,  the Agency strives to formulate and implement actions leading to
a compatible balance between human activities and the ability of natural systems to support and
nurture life.  These laws direct the EPA to perform research to define our environmental
problems, measure the impacts, and search for solutions.

       The Risk Reduction Engineering Laboratory is  responsible for planning, implementing,
and managing research, development, and demonstration programs to provide an authoritative,
defensible engineering basis in support  of the policies, programs, and regulations of EPA with
respect to drinking water, wastewater, pesticides, toxic substances, solid and hazardous waste,
and Superfund-related activities. This  publication is one of the products of that research and
provides a vital communication link between researchers and users.

       These Abstract Proceedings from the 1992 Symposium provide the results of projects
recently completed by RREL and current information  on projects presently underway. Those
wishing additional information  on these projects are urged to  contact  the  author or the EPA
Project Officer.

       RREL sponsors a symposium each year in order to assure that the results of its research
efforts are rapidly transmitted to the user community.
                              E. Timothy Oppelt, Director
                         Risk Reduction Engineering Laboratory

       The Eighteenth Annual Risk Reduction Engineering Laboratory Research Symposium was
held in Cincinnati, Ohio, April 14-16, 1992.  The purpose of this Symposium was to present the
latest significant research findings from ongoing and recently completed projects funded by the
Risk Reduction Engineering Laboratory (RREL).

       These Proceedings  are organized into two sections, Sessions A and B, which contain
extended abstracts of the paper presentations. A list of poster displays is also included. Subjects
include remedial action, treatment, and control technologies for waste disposal, landfill liner and
cover  systems,  underground  storage  tanks,   and  demonstration  and   development  of
innovative/alternative treatment technologies for hazardous waste.   Alternative technology
subjects include thermal destruction of hazardous wastes, field evaluations,  existing treatment
options, emerging treatment processes, waste minimization, and biosystems for hazardous waste
destruction.                             !

                             TABLE OF CONTENTS
Session A
      Solidification/Stabilisation of High Level Inorganic and Organic
      Soils at Robins Air Force Base  .	.  . .  .

Review of Soil Vapor Extraction Microcomputer Models   	  .5

Remediation of Lead Contaminated Soil .....;...	•-.	•... .11

Destruction of Organic Wastes Using Concentrated Solar Radiation	  16

Assessment of Relative POHC Destruction at EPA's Incineration
Research Facility	.20

PACS vs CO as Surrogates for Trace Combustibles	25

High Energy Electron Beam Irradiation: An Emerging Technology
for the Destruction of Organic Contaminants in Water, Wastewater,
and Sludge	28

Carbon  Dioxide Cleaning of Contaminated Surfaces	32

Evaluation of Three Oil Filter Designs for Pollution Prevention
Effectiveness	36

The Waste Reduction Evaluations at Federal Sites Program	39

Measuring Pollution Prevention	.43

Two Pollution Prevention Technology Evaluations for the Printed
Circuit Board Industry		46

Evaluation of Emulsion Cleaners at Air Force Plant Number 6	50

Evaluation of Filtration and Distillation Methods for Recycling
Automotive Coolant  	55

The Use of Hydraulic Fracturing to Enhance In Situ Bioremediation	59

In Situ Treatment of Soil Contaminated with PAHs and Phenols	62

Long-Term Durability of Solidified/Stabilized Materials 	67

Session A (continued)
      Metals Partitioning Resulting from Rotary Kiln Incineration
      of Hazardous Waste	•	72

      Engineering Analysis of Metals Emissions from Waste                '
      Incinerators Field Data	77

      Effect of Municipal Waste Combustion Ash Monofill Leachate
      on Selected Containment Barrier Components	 81

      Solidification/Stabilization for Lead Battery Site - A Two
      Stage Program	86

      Rotary Kiln Incineration of Spent Pdtiiner from
      the Manufacturer of Aluminum  . .,.	 90

      Selective Recovery of Nickel and Cobalt from Electromachining
      Process Solutions	  . 96

Session B
  r  -T--' ^                               I

      Treatment of Dilute Hazardous Waste Streams by
      Sorption/Anaerobic Stabilization ..;....	..."...  101
      Development of a Novel Biofilter for Aerobic Biodegradation
      of Volatile Organic Compounds (VOCs)	110

      Onsite Biological Pretreatment Followed by POTW Treatment
      of CERCLA Leachates  .......'	 . .	. .  114

      Two U.S. EPA Bioremediation Field Initiative Studies:
      Evaluation of In-Situ Bioventing .	  118

      Measurement of the Effect of Temperature on Oxygen Uptake  ...........  124

      A Fundamental Kinetic Study of the Anaerobic Biodegradation
      of Chloroform and its products with Various Co-Substrates
      in Mixed Culture Chemostats  .  . .'•	  130
      Emissions of Organics from Bioslurry Reactors Treating Soil
      Contaminated with Wood  Preserving Waste	  135

      Design of Full Scale Debris Washing System	138

Session B (continued)
      Treatment of Hazardous and Toxic Liquids Using Rochem
      Disc Tube Technology	.  .  143

      The Site Demonstration of the Retech Plasma Centrifugal Furnace	  146

      Site Demonstration of the Soiltech Anaerobic Thermal Processor	  149

      The Site Investigation Robot	  152

      Evaluation of the Air-Sparged Hydrocyclone	  155

      Assessment of Binding Energies Between Organic Contaminants
      and Soils and Sediments	  160

      Bioavailability and Biodegradation Kinetics of Organics in Soil	  163

      Removal of Creosote from Soil by Thermal Desorption	  170

      Slurry Reactor Bioremediation of Soil-Bound Polycyclic Aromatic
      Hydrocarbons	174

      Adsorptive Filtration for Treatment of Metals at Superfund Sites	  179

      Phase Separation and Soluble Pollutant Removal By Means of
      Alternating Current Electrocoagulation	  184

      Fluid Extraction-Biological Degradation of Organic Wastes	  189

      Remediation of Leaking USTS on Native American Lands	  194

      Laboratory Study of Interactions Between Polychlorinated
      Biphenyls and Quicklime	 . . . ;	  .  200

      Risk Reduction Engineering Laboratory (RREL) Treatability Database  	205

      Development of  Biodegradation Kinetics for Mixed Substrate System	  206

Remedy Screening Tests for Extraction Technologies
Ari Selvakumar, FW Enviresponse

Ozone/Ultraviolet Light Treatment of Dithiocarbamate Pesticides in WasteWatef
Mark Briggs, Radian Corp              ;

Alternatives for "Clean" Production      ;                          •         '       .. '
Mary Ann Curran, U.S. EPA, RREL    '

Research Study Opportunities at EPA's Test and Evaluation Facility
Francis Evans, U.S. EPA, RREL        :
RREL Superftind  Technical Support Program
Ben Blaney, U.S. EPA, RREL          j
Development of Small-Scale Evaluation Techniques for Fungal Treatment of Soils*
Frederic Baud-Grasset, U.S. EPA, RRELi
Subsurface Remediation of Gasoline  by Air Sparging and SVE
Chien Chen, U.S. EPA, RREL
                                     I                        "                •-•
Ultrasonic Enhancement of Soil Washing
Asim Ray, FW Enviresponse           |

Innovative Clean Technologies Project   i
Angel Martin-Dias, Center for Hazardous (Materials Research

Onsite Anaerobic Biological Process Addressing Explosives and Pesticides
Ronald Crawford, University of Idaho   j

Screening Methodology for Assessing Cleanup Technologies for Leaking Underground Storage
Tank Sites                            !
Chi-Yuan Fan, U.S. EPA, RREL

Pesticide Treatability Data Base         i
David Ferguson,  U.S.  EPA, RREL

Development of Biodegradation Kinetics for Mixed Substrate Systems
Rakesh Govind, University of Cincinnati j
Waste Analysis Plan Review Advisor (WAPRA) to Assist RCRA Permit Reviewers
Daniel Greathouse, U.S. EPA, RREL   !                                    ,

Leachate Recirculation as a Remedial Action at Problematic Municipal Solid Waste Disposal
Stephen Harper, Engineering Science

RREL Remedy Screening Lab
Gerard Roberto, Center Hill Facility

Pilot Program for the  Treatment of Mining Wastes, Butte, Montana
Jonathan Herrmann, U.S. EPA, RREL

Results from the U.S. EPA Municipal Solid Waste Innovative Technology Evaluation Program
Lynann Kitchens, U.S. EPA, RREL

RREL RCRA Corrective Action Technical Support Program
Doug Grosse, U.S. EPA, RREL

Characterization of Inorganic Wood Preserving Waste:  F035
DanPatel, SAIC

SITE Demonstration of the Horsehead Resource Development Co.,  Inc.
Marta Richards, U.S. EPA, RREL

NATO/CCMS: Pollution Prevention Strategies for Sustainable Development
Harry Freeman, U.S. EPA, RREL

Pollution Prevention in Public Agencies
Emma Lou George, U.S. EPA, RREL                •

Treatability Tests on Ash from Incineration of Spent Potliner Waste (KO88)
Vijay Rao, IT Corporation

Feasibility of Rubber Battery Casings as a Fuel Substitute
James Stumbar, FW Enviresponse

U.S. EPA Waste Minimization Assessment Centers
William Kirsch, University City Science Center

California EPA WRITE Program
Robert Ludwig, California Dept. of Toxic Substances Control

Contaminated Soil and Debris Technology Transfer Program
Joyce Perdek, U.S. EPA, RREL

CERCLA Treatability Guidance          \
Jim Rawe, SAIC

Evaluating Physical and Biological Changes in Soils Caused by Superfund Treatment
Pat Lafornara, U.S. EPA, RREL
The Municipal Waste Landfill as a Biological Reactor
Norbert Shoemaker, Gulf Coast Hazardous Substance Research Center

Scanning Electron Microscope Monitoring of Biological Granular Activated Carbon Hazardous
Waste Treatment Processes              \
Steven Safferman, U.S. EPA, RREL     i

Utilization of the Incineration Research Facility for Superfund Treatability Testing
Howard Wall, U.S. EPA, RREL         j

                               SOLIDIFICATION/STABILIZATION OF
                             HIGH LEVEL INORGANIC AND ORGANIC
                               SOILS AT ROBINS AIR FORCE BASE

                               Terry Lyons
                               U.S. EPA, RREL
                               26 Martin Luther King St.
                               Cincinnati, OH 45268
                               (513) 569-7589

                               Paul V. Dean
                               PRC Environmental Management, Inc.
                               1505 Planning Research Dr., Suite 220
                               McLean, VA  22102
                               (703) 883-8806
        Solidification/stabilization technologies have been applied widely and generally have been
effective in immobilizing metal and other inorganic contaminants at hazardous waste sites.  Solidifica-
tion/stabilization technologies have been less effective in immobilizing organic contaminants, because
solidification alone may not reduce the mobility and toxicity of hydrophobia constituents. In addition,
treatment of wastes containing volatile organic compounds (VOC) by solidification/stabilization generally
has consisted of partitioning VOCs to the air either through aeration (such as materials handling and
mixing) or through heat of reaction with treatment reagents.

        To constitute treatment under Superfund, a solidification/stabilization technology must
demonstrate a significant reduction (90 to 99 percent) in the concentration of chemical constituents of
concern. During the last 10 years, various innovative solidification/stabilization technologies have
emerged that are capable of treating wastes containing organic as well as inorganic contaminants.
These innovative solidification/stabilization technologies have  involved the use of surfactants and other
reagents that chemically stabilize contaminants in conjunction with solidification.

        One innovative solidification/stabilization technology,  developed by Wastech, Inc., is currently
being tested in the U.S. EPA Superfund Innovative Technology Evaluation (SITE) program at Robins Air
Force Base (Robins AFB) in Warner Robins, Georgia. An on-base landfill  cell of approximately 1.5 acres
was used for the disposal of industrial wastewater treatment sludge, as well as solvents, cleaners, paint
removers,  hydraulic fluids, and oils. Those wastes were deposited in the cell over a period of
approximately 16 years ending in 1978.   Soils at the site are contaminated with a variety,of VOCs, such
as 1,2-, 1,3-, and 1,4-dichlorobenzene, trichloroethylene, benzene, toluene, ethylbenzene, and xylenes,
and with chromium, nickel, and lead.

        The Wastech solidification/stabilization technology is being evaluated to determine the
effectiveness of the technology in treating organic and inorganic contaminants. The evaluation of the
Wastech technology will include determining the structural properties of the treated waste and assessing
the loss of VOCs during the treatment process and during post-treatment  curing.

METHODOLOGY                         !

        The first phase of the Wastech treatrhent technology involves adding proprietary liquid chemicals
and catalysts to the waste, which will result in the formation of micelles. According to Wastech, after
exposure to the liquid reagents, the contaminants are chemically stabilized and volatilization stops. The
second phase of the treatment involves physical solidification and stabilization in a mixture of pozzolanic
binders and Portland cement The resulting grout-like mixture is deposited into containers or  in
engineered excavations for curing and disposal.

        The evaluation of the Wastech technology will consist of a pilot-scale demonstration at Robins
AFB.  The evaluation will be based primarily 0n 1) determining if the technology can reduce the level of
organic contaminant extractability as measured by total waste analysis (SW 846 Methods 8240 and
8270), and 2) determining if the Wastech technology reduces leachability and mobility of both organic
and Inorganic contaminants as measured byithe Toxicity Characteristic Leaching Procedure (TCLP) and
other leaching procedures such as TCLP-Disjtilled Water.  The technology evaluation also will be based
on the structural properties of the treated waste, the loss of VOCs during treatment and curing,  the
volume and mass increase of the treated waste, and treatment variability from  batch to batch.

        Contaminated soil from the Robins A'FB site will be excavated, screened, and conveyed by a
screw auger to the treatment mixer.  At each excavation location, a 4-foot diameter casing,
approximately 10 feet long, will be driven  into the landfill, using a vibrating hammer. The casing will
allow clean removal and temporary storage of overburden without adjacent overburden collapsing into
the hole. After the overburden has been augered out, a modified mud bucket  will collect the
contaminated soil in single 1- to 2-cubic-yard lifts. The excavated waste will be transported directly to
the screen and screw conveyor in the mud bucket, minimizing material handling and attendant VOC
emissions. The overburden will be used to backfill the excavation following waste removal.

        The mixer is trailer-mounted and contains mixing paddles and two high-speed rotary cutting
blades. Calibrated load cells (scales) are located under each leg of the mixer, providing the accurate
weight of all materials added. With the mixer in the trailer  are storage tanks for water, liquid reagent and
catalyst, pozzolanic binders,  and portland cement, as well  as a control booth and wet scrubber/carbon
adsorption system to control air emissions,  the mixer will be kept under negative pressure, with the air
drawn through a tank of scrubber water and then through  two canisters of granular activated carbon that
are staged in series.                       :

        Raw- and treated-waste samples collected during the technology demonstration will be analyzed
by a variety of chemical and  physical tests (Such as Methods 8240, 8270, TCLP and unconfined
compressive strength). To account for any interferences introduced by the treatment reagents and
process water, a reagent mix "blank" batch will  be run using  clean sand.  The sand and water, as well as
the "treated" material, will be sampled and analyzed upon discharge from the mixer.

        Loss of VOCs during treatment and curing will be  measured in two ways.  First, for each batch
of soil treated in the mixer, the scrubber water and carbon canisters will be analyzed for VOCs.
Sampled clean water and carbon will be used for each treatment batch. Second,  upon discharge  of
treated waste, a tared 5-gallon bucket will be filled with the waste, immediately covered, weighed, and
placed inside a glove box with Inflow and outflow ports (see  figure).  The glove box then will be sealed
and purged with nitrogen, using a low-volume air pump. Activated carbon tubes, in series to prevent
breakthrough, will be attached to the outflow port and the  bucket cover removed.  Carbon tubes will be
changed daily for one week and analyzed for VOCs.

                            REPRESENTATIVE GLOVE BOX

       A borehole program at the Robins AFB site to identify excavation locations for the technology
demonstration was conducted in July and August 1991.  Soil samples were collected from various
locations at a depth of 6 to 8 feet.  Representative results of the borehole sampling program are shown
in Tables 1 to 3.


       Bench-scale testing results should be available in March or April 1992. A pilot-scale field
demonstration currently is scheduled for April or May 1992.

                    TABLE 1.  VOCs AT ROBINS AFB - METHOD 8240

                          Concentrations are in mg/Kg (ppm)
Sample Location
1 ,2-DIchloroethene (total)
1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
i 98
, 33
TEX » Total toluene, ethylbenzene, and total xyienes; no benzene detected.



                          Concentrations are in mg/Kg (ppm)

1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
1 ,2,4-TrichIorobenzene
2-Methyl naphthalene
; A
i 336
, 2,560
Sample Location

                      TABLE 3. METALS AT ROBINS AFB - TCLP

                          Concentrations are in mg/L (ppm)
                                                 Sample Location
i 0.371
I 0.371


                                 Chi-Yuan Fan
                 Superfund Technology Demonstration Division
                    Risk Reduction Engineering Laboratory
                     U.S.  Environmental  Protection Agency
                            2890 Woodbridge Avenue
                           Edison, New Jersey 08837

      Soil Vapor Extraction (SVE) is a process in which volatilization of
residual organics is enhanced and contaminated gas is removed from subsurface
soils.  The technology is commonly used to remediate volatile organic
compounds released from underground storage tank (UST) systems.  Across the
nation, numerous consultants have designed and operated SVE for cleaning up
gasoline and solvents contaminated soil.  However, despite the wide
application of SVE systems, only scanty information is available for
evaluating the feasibility of SVE technology and predicting the efficiency of
system performance.

      The US EPA Risk Reduction Engineering Laboratory has recently prepared a
document to provide guidance for designing and implementing a soil vapor
extraction treatability study in support of remedy selection at Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) sites.  As
stated in the guidelines, screening and evaluation of the SVE technology
applicability necessitates understanding SVE processes through modeling
techniques at an early stage of the technology implementation.

      A model is a physical or mathematical construct that simulates or
approximates the behavior of an actual physical process.  Models are used to
understand processes or portions of processes that have a high degree of
complexity or cannot be readily understood by direct observation.  In leaking
underground storage tanks site or hazardous waste site evaluations, models are
particularly valuable since modeling the behavior of a soil-vapor-groundwater
system prior to the construction of a remediation system can reduce the cost
associated with trial and error system design and operation.

      If SVE processes can be adequately modeled, then the remedial design
consultant will be better able to examine the process feasibility, to predict
potential performance, and to develop system engineering design criteria prior
to SVE implementation.  This paper presents a brief overview of the identified
micro-computer models that simulate soil vapor transport due to the influences
of a SVE system and evaluate the feasibility of using SVE system for site


      To effectively design a SVE system, an understanding of the mechanisms
controlling the fate and transport processes and the site characteristics
which affect them is required.  The major processes that affect SVE are
advection, diffusion, dispersion, partitioning, and abiotic and biological

       Mathematical models have been developed to describe results of
 laboratory SVE column experiments, as well as results from field scale
 implementation of SVE.  In order to identify models which are applicable for
 use in evaluating SVE systems, a larger group of models, subsurface vapor
 transport models, was examined.  The models within this group consist of seven
 model types:                                      ,      ,
        Models developed to simulate laboratory column studies.
        Models developed to simulate laboratory pilot (sandbox) studies.
        SVE screening models.
        Models developed to simulate the effect of SVE at the field scale.
        3-D vapor flow models for field scale applications.
        3-D multi-phase fate and transport models having a vapor flow
        component for field scale applications.
        Groundwater flow models used to approximate vapor flow.
        Radon gas fate and transport models.

      While each of these types of models is important in describing some
 portion of subsurface vapor transport,  this presentation addresses only those
 models which can simulate SVE systems  on a personal  computer.   Table 1
 summarizes four general  types of models which are discussed  in the following

      1.   Column Models — Column models are developed to simulate laboratory
 column studies that gauge the relative  importance of various  fate and
 transport  processes under simplified land controlled  column conditions.   SVE
 treatability study and research have been conducted  with column studies  with
 computer modeling.

      Wilson (1991)  developed  a SVE  column model  to simulate one dimensional
 flow in  laboratory column studies.  The model  considered local  equilibrium
 betv/een  vapor phase,  aqueous  phase, adsorbed  state,  and  nonaqueous  liquid
 phase.^  Advection and diffusion/dispersion in  the vapor  and aqueous  phases are
 taken into account,  and  biological  degradation is also modeled  as  a  first-
 order process occurring  in the aqueous  phase.   In addition, the user  can
 determine  the sorption parameters based  on the test  results according to
 Freundlich,  Langmuir,  and  BET adsorption  isotherms characteristics.
      2.  Screening  Models  - SVE  screening  models  are models which are
 primarily  used  in a  semi-quantitative fashion  to  estimate whether SVE is
 feasible for  application at a  specific  site.   In  addition, such a model may
 provide estimates of  some  design parameters for sizing a SVE system.  Johnson
 et al. (1990, 1990a)  presented a practical  approach  to screening the
 feasibility of using  SVE at a  particular site.  The  approach is based on
 equations which estimate VOC removal rates  and pressure  distributions related
 to various SVE design parameters.  Based on this  approach two models.
 HYPERVENTILATE and VENTING, were developed.

     HYPERVENTILATE was developed as a user friendly, interactive, software
 guidance system that operates as a "decision tree" for investigating the
 potential implementation of SVE at a ^iven site.  It was designed for the
Apple Macintosh HyperCard environment,  and consequently requires the HyperCard
program for operation.  The model will  not completely design a vapor
extraction system, predict exactly how many days  it should be  operated, or


predict the overall effectiveness of a SVE system.  It was designed to be used
as a guide to a structured thought process to: (a) identify and characterize
required site data, (b) decide if soil venting is appropriate at a site, (c)
evaluate air  permeability test results, (d) estimate the minimum number of
extraction wells, and (e) estimate how resultsat agiven site might differ from
the ideal case.  The organizational basis used in Hyperventilate is a system
of multiple card files.  The main card stack is called "Soil Venting Cards".
Since individual cards within this stack may require further explanation,
there are secondary card stacks that can be accessed through individual cards.
These secondary stacks include the "Soil Venting Help Stack", the "Air
Permeability Test" stack, the "Aquifer Characterization" stack, and the
"System Design" stack.  Most of the SVE system parameters are estimated under
the topics that deal with SVE feasibility, system design and field testing.

     VENTING — This screening model for estimating the VOC removal rate from
the vadose zone under SVE conditions assumes steady gas flow, equilibrium
partitioning between the free product and vapor phases and complete mixing of
free product and vapor to estimate the reduction  in mass of each component of
the contaminant over the time of extraction.  The mass balance portion only
considers partitioning from the free product phase into the vapor phase.  It
assumes contributions to the vapor phase by the aqueous and adsorbed phases
are negligible.  The key parameter which controls the results of VENTING is
the volumetric gas flow rate which is in contact with the contaminated soil.
The flow rate may either be input directly based on field measurements or may
be estimated from the gas permeability of the soil and the vent pressure.   If
the gas permeability is not known, "VENTING" provides a method of estimating a
value for this parameter using air permeability test data.

     3.  Three-Dimensional Vapor Flow Models  — This category of subsurface
vapor transport models addresses the three-dimensional flow of soil vapor
through a porous medium due to the pressure gradient established by an
extraction well.   Such models do not consider the contaminant concentrations
in the  soil  vapor  but  do simulate the compressibility of  the vapor.  CSUGAS is
one of  this  type models.   It  is a three  dimensional, finite difference model
which numerically  simulates the flow field of a compressible gas  in a porous
medium  due to  the  influences  of a SVE system.  The finite difference method is
used to numerically  approximate a solution to the system  of equations.   Use of
this method  allows for application to a  heterogeneous and isotropic porous
medium  with  gaseous  flow under steady state or transient  conditions.  The
model  can  be used  to select design parameters, determine  the feasibility of
SVE at  a  particular  site,  or  evaluate proposed modifications to existing SVE

     4.   Ground  Water  Flow Models  —  Another  approach which  has been  used  to
predict the  pressure distribution  and flow  of a  SVE  system  for  design  purposes
 is  to  use ground  water flow models.   The equations describing  vapor and  ground
water  flow in a  porous medium are  similar enough  to  warrant  the use of  ground
water  flow models  to approximate  the  pressure field  and  flow of a  given system
design.  The advantages  of using  ground water models are that  many of  these
models  are readily available,  well  documented, validated, and  may already  be
familiar to  the user.   MODFLOW is  a  commonly  used ground water flow model.
This  model  is a three-dimensional,  finite difference ground water flow model
 developed by the USGS as a modular model capable of  simulating many  hydrologic
 systems (McDonald and Harbaugh 1985).   It has several  optional  features which

 are not applicable for simulating air flow.  The model is divided into
 'packages", each of which represents a hydrologic or computational featurel
 Packages are further divided into ''modules" which are subroutines designed for
 use in a particular package.  For $VE applications, the two packages that are
 the most important are the Block Centered Flow (BCF) Package which simulates
 flow within a porous media and the Basic Package.  The Basic Package includes
 definition of:  the number of rows; columns and layers in the finite
 difference grid, timing of the analysis, the initial pressures (head for
 ground water), the boundary conditions, the timing and format of the output
 and a volumetric balance.         [

 CONCLUSIONS                       i

      Recent designs of SVE systems for VOC removal have mostly been
 empirically based due to the simplicity of the process and to a lack of
 analytical  tools capable of aiding in system design.  While it is possible to
 empirically design a SVE system which will extract VOC vapors, design of an
 efficient system which will effectively target the entire contaminated soil
 volume and  reduce VOC residuals to an acceptable level,  requires predictive
 capabilities,  especially at sites with very heterogeneous soils and/or widely
 varying topography.   Predictive capabilities such as those provided  by a
 correctly applied model are needed to estimate the change in effectiveness of
 a  system due to varying the blower ;size,  well  configuration, screened
 interval, and  other system parameters.

      Many numerical  model have  beeri  used  in actual  field  situation to evaluate
 the effectiveness of SVE  in removing organic vapors.   Modeling yields
 meaningful  results when the appropriate background  information is used.
 Sensitivity analyses  reveal  the importance of  soil  moisture,  temperature,
 heterogeneities  of the  soil  and other factors  in  controlling the migration of
 volatile constituents through the u'nsaturated  zone.   Furthermore, the process
 of contaminants  desorption from soil  particles, which  occurs  through  three
 consecutive mass transport steps,  plays an  important  role  in  determining final
 cleanup  efficiency and  will  generate  significant  differences  in  removal rate
 between  the various  types  of soils and  volatile organic components.

 Acknowledgments.   The author thanks Dr. John Eisenbeis of  Camp Dresser & McKee
 Inc., Denver, Colorado  for his  study on the  soil vapor extraction numerical
 models assessment  under EPA Contract No. 68-03-3409, WA 3-09.


 Johnson, P.C.; C.C. Stanley, M.W. Kemblowski, D.L. Byers and J.D. Colthart
 1990. A Practical Approach to the Design, Operation, and Monitoring of In Situ
 Soil Venting Systems. Ground Water Monitoring Review, 10(2) p. 159.

 Johnson, P.C.;  M.W. Kemblowski and J.D. Colthart. 1990a. Quantitative Analysis
for the Cleanup of Hydrocarbon Contaminated Soils by In Situ Soil Ventina
Ground Water, 28(3) p. 413.

McDonald, M.G.  and A.W.  Harbaugh. 1988. A Modular Three Dimensional  Finite
Difference Ground Water Flow Model.  USGS Book 6.

Sabadell, G.P.; J.J. Eisenbeis, D. VanZyl and O.K. Sunada. 1988.  CSUGAS -
Flowfield Model For In Situ Volatilization of Organic Compounds in Soils,
Colorado State University Report to Argonne National Laboratory.

Wilson, D.J. 1991. Movement of a Volatile Organic Compound in a Soil Vapor
Extraction Column. (Unpublished paper)








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                                          Walter Urban
                                 Foster Wheeler Enviresponse, Inc.
                                    2890 WoodbrkJge Avenue
                                    Edison, New Jersey 08837
                                         S. Krishnamurthy
                               Risk Reduction Engineering Laboratory
                                    2890 Woodbridge Avenue
                                    Edison, New Jersey 08837
        Lead contaminated soil in urban areas is of major concern because of the potential health risk to
children. Many studies have established a direct correlation between lead in soil and elevated blood lead
levels in children (Fairey and Gray,  1970;  Neri et al.,  1978;  and Rabinowitz and Bellinger, 1988).  In
Minneapolis, Minnesota, Mielke et al. (1983)  reported that 50% of the Hmong children with lead poisioning
were in areas where soil lead levels were between 500 and 1000 micrograms per gram (ug/g), and 40% of
the children suffering from lead  poisioning lived in areas where soil lead levels exceeded 1000 ug/g.

        In urban areas, lead pollution in soil has come from many different sources. The sources include
lead paint, lead batteries and  automobile exhaust.  Olson and Skogerbee (1975) found the following lead
compounds in soils where the primary source of pollution was from automobiles:  lead sulfate, lead oxide,
lead dioxide, lead sulfide, and metallic lead. The primary form of lead found was lead sulfate. Lead batteries
contain  metallic lead, lead sulfate, and lead dioxide.  The primary form of lead found is lead sulfate. Lead
sulfate, lead tetraoxide, white lead, and other forms of lead have been used in the manufacture of paints for

        At present, two remediation techniques, solidification and Bureau of Mines fluosilicic acid leaching,
are available for lead-contaminated sites.  The objective of the present investigation at the Risk Reduction
Engineering Laboratory(RREL), Edison, was to try to solubilize the lead species by appropriate reagents and
then recover the contaminants by precipitation as lead sulfate, using environmentally acceptable methods.
A multistep extraction process was developed. The apparatus used for mixing was a LabMaster mixer, with
variable speed and high-shear impeller.

        Previous work had used nitric acid for dissolving metallic lead.   Owing to the environmental
concerns, it was decided to use acetic acid in the presence of oxygen. The theoretical justification for this
approach is the favorable redox potential for the reaction between metallic lead, acetic acid, and gaseous

        In the first step a water slurry of lead-contaminated soil is reacted with ammonium carbonate to
convert  lead sulfate to lead carbonate. After filtration, the soil is reacted with gaseous oxygen in an acetic
acid medium.  In this second  step metallic lead and lead carbonates are solubilized as lead acetate. The
soil is filtered and then reacted  (third step)  with manganese acetate.  This step converts lead dioxide to
soluble lead acetate, leaving insoluble manganese compounds as a byproduct. The filtrates from the three
steps are combined to precipitate insoluble lead sulfate, which  is a usable product.


        To determine what mixing speed and oxygen flow rate to use, 5.0 grams of metallic lead was mixed
at different mixing speeds and at different oxygen flow rates in the presence of sand for one hour. The sand
was added to keep the metallic lead dispersed throughout the solution. At the beginning and end of the
runs, the pH of the lead-sand-acetic acid mixture was measured to determine if the desired reaction was
occurring. The dissolved oxygen concentration was measured every 10 minutes. At the end of the run, three
samples were taken for determination of lead by atomic absorption spectroscopy.

        The second experiment performed was a rate of reaction study.  In this study, every ten minutes
a sample was taken out for lead determination to find how long it takes for maximum metallic lead solubility
to occur in the  presence of the oxygen.  These tests were done for 70 minutes.  Three different sets of
conditions were studied. In the first set of conditions, 10,000 milligrams per liter (mg/L) of metallic lead was
mixed in 1.0M acetic acid with an oxygen flowj rate of 73.4 milliliters per minute (mL/min).  In the second
set of conditions, 20,OOOmg/L of metallic lead was mixed in 0.01 Molar(M) acetic acid with an  oxygen flow
rate of 73.4ml_/min. In the third set of conditions, 10,000 mg/L of metallic lead was mixed in  0.1 M acetic
acid with an oxygen flow rate of 73.4 mL/min. Temperature pH, and oxygen solubility were also determined.
The lead concentrations in the sample were determined via atomic absorption spectroscopy.

        The solubilization of lead dioxide involves the use of manganese acetate to reduce and solubilize
the lead dioxide. 1.15 grams of lead dioxide was added to a beaker containing 500 mL of 1.0 M acetic acid.
To twelve beakers of this mixture, manganese acetate was added at the following levels: 0.5,  1.0, 1.5, 2.0,
2,5 and 3.0 grams. The contents were mixed for a period of one hour,  then filtered.  Three samples were
taken from the filtered solution for lead determination.
        In separate experiment, samples of silt loam from Bayou Bonfouca,  Louisiana were spiked with
10,000, 5,000 and 1,000 milligrams per kilograms (mg/kg) of lead. Four different types of lead were added
to the silt loam.  Lead sulfate, white lead, lead dioxide, and metallic lead were added to the soil in the ratio
6:2:1:1.   The extracting solutions in the following steps were added at  a ratio of 8:1. The first step was to
add ammonium carbonate solution to convert the lead sulfate to lead carbonate The sample was mixed for
5 minutes. Three samples were taken from the filtrate for lead analysis. The second step was to add 1.0
M acetic acid to the sample in the presence of oxygen to solubilize the lead carbonate, metallic lead, and
white lead. The lead in solution was determined by atomic absorption spectroscopy.  After the second step,
the residue was leached with deionized water. The leachate was analyzed for lead. The filial step involved
the use  of manganese acetate in 1.0 M acetic acid as a means of removal of the lead dioxide from the soil.
At the 10000 parts per million(ppm) lead level, the above procedure was done twice to see if any additional
lead could be extracted.


        The solubilization of metallic lead in a sand medium showed the  importance of choosing the proper
mixing speed and  oxygen flow rate.  As the  oxygen flow rate was increased from 24.1  ml/min to  59.5
ml/min, an increase in the solubility of metallic lead was observed. Oxygen flow above 59.5 ml/min did not
result in an increase in metallic lead solubility. Increasing the mixing speed from 400 revolutions per minute
rpm) to 800 rpm caused almost a 25% increase|in metallic lead solubility. Metallic lead solubility at 400 rpm
averaged 63%, while at 800 rpm mixing speed^ metallic lead solubility averaged 84%.

        The complete results for the manganese  acetate test can be found in Table 1.   The use of
manganese acetate showed that, when added at a level  of 1.0gram/500 milliliter (g/mL), more than 55% of
the lead dioxide (2000mg/L)  dissolved.   Additional  manganese acetate  appeared to result in a slight
decrease in lead dioxide solubility.

Manganese Acetate Used
Lead Added
Lead in Solution
(ppm) (%)
        In the rate of reaction studies, the solubilization of lead varied depending upon the ratio of metallic
lead to acetic acid. When metallic lead was added at 10000 mg/L rate to a 1  M solution of acetic acid
representing approximately 10 to 1  reagent to lead ratio, 72% of the added lead was in  solution in 10
minutes. After 20 minutes, 89% of the added metallic lead was found to have dissolved. The increase in
metallic lead solubility was then much slower and levels off at 60 minutes with 95.5% of the lead going into
solution.  When the ratio of reagent to  metallic lead was 1.3 to 1, 73.3% of the  metallic lead went into
solution within 10 minutes.  After seventy minutes, the metallic lead solubility had only increased to 80.2%
of the added lead.  When lead was added at 20,000 mg/L to a 0.01 M acetic acid solution, lead solubility
leveled off at 10 minutes of 4.8% of the added lead going into solution.  After the first ten minutes, lead
solubility decreased and pH rose above 9.6.

        The  results of experiments with lead-contaminated  soils are summarized in Table 2. Using soil
spiked with lead at 5000 mg/kg  of soil, approximately 82% of the lead went into solution from the above
procedure.  In the first step where carbonation was done, only 0.7% of the lead  went into solution. In the
oxidation step, 63.8% of the applied lead went into solution.  Leaching the residue with water resulted in an
additional 3.5%  of the lead being removed from the soil. The final step where manganese  acetate was
added resulted in an additional 14.2% of the added lead going into solution.

        Using soil spiked with lead at 1000 mg/kg of soil, approximately 80% of the lead went into solution.
The carbonation step resulted in  1.9% of the lead going into solution. The oxidation step resulted in 57.6%
of the lead going into solution.   Leaching the  residue with deionized water resulted in the removal  of
additional 4.4% lead from the soil. The addition of manganese acetate resulted in 15.9% of the added lead
going into solution.

        The 10000 mg Pb/kg of  soil sample was run through the three-step process twice.  After the first
 run through the three-step extraction procedure, 82.9% of the lead added was in solution. The second run
through the three-step procedure resulted in an additional 6.4% of the added lead being solubilized. A total
 of 89.3% of the added lead was  solubilized by duplicating the three step process. The oxidation step in
the first set of extractions resulted in 65.1% of the lead going into solution.  The  manganese acetate
 extraction step resulted in 13.8%  of the added lead being solubilized. The second set of extractions resulted
 in an additional 4.6% of the lead being removed in the oxidation step with the remaining lead removal being
 divided between the deionized water and manganese acetate leaching steps.

        After the above treatment, the soil was subjected to the Toxicity Characteristic Leaching Procedure
 (TCLP) test. The soil passed the test with a value of 3 parts per million (ppm) in the leachate.



Reagent used
Ammonium Carbonate
Oxygen and Acetic Acid
Deionized Water
Manganese Acetate

Ammonium Carbonate
Oxygen and Acetic Acid
Deionized Water
Manganese Acetate

Lead input
Lead in solution
Removal efficiency


Ammonium Carbonate
Oxygen and Acetic Acid
Deionized Water
Manganese Acetate
Ammonium Carbonate
Oxygen and Acetic Acid
Deionized Water
Manganese Acetate
Deionized Water
  First Extraction
10000              5.0
10000            847.3
10000            207.3
10000            183.2
10000           1242.8

Second Extraction*
10000              0.7
10000             62.6
10000             32.7
10000             12.2
10000              5.2
*  Here the removal efficiency was calculated bn the starting concentration in the first step.

CONCLUSIONS                           I

       The results in the silt soil show that a three step process involving manganese acetate, ammonium
carbonate, acetic acid and oxygen has the potential for effectively removing lead sulfate, lead dioxide,
metallic lead, and white lead from a soil.   The three step extraction process resulted in 80% or greater
solubilization of the lead that was added to a silt loam.

       At present,  research is continuing  on the study of this process for removing the lead compounds
of concern in urban environments and more data will be available when the conference is held.


1.      Fairey, F. and Gray, J.  1970.  Soil lead and pediatric lead poisoning.  S. C. Med. Assoc. 66:79-82.

2.      Neri, I., Johansen, J,, Schmitt, N,, Pagan, R,, and Hewitt, D. 1978.  Blood lead levels in children in
       two British Columbia communities, in Hemphill, D. ed. Twelfth Trace Substances Conference. Univ.
       of Missouri, Columbia, MO. pp 403-410.

3.      Rabinowitz, M.  B. and  Bellinger, D. C.  1988.  Soil lead-blood lead relationship among  Boston
       children. Bull. Environ. Contam. Toxicol. 41:791-797.

4.      Mielke, H. W., Blake, B., Burroughs, S., and Kissinger, N. 1983. Urban lead levels in Minneapolis:
       The case of the Hmong children. Environ.  Res. 34:64-76.

5.      Olson, K. W. and Skogerbee,  R. K.  1975.   Identification of soil lead compounds from automotive
       sources. Environ. Sci. Technol. 9:227-230.

                           Barry Bellinger, John L. Graham, and Joel M. Berman
                                     Environmental Sciences Group
                                  University of Dayton Research Institute
                                            300 College Park
                                        Dayton,;OH 45469-0132
        We have recently demonstrated that the rate of many gas-phase photochemical reactions can be increased
 by initiating these reactions at elevated temperatures i(e.g., > 400°C) (1,2). The development of very high-
 temperature photochemistry has raised exciting possibilities for applications such as the destruction of toxic
 organic wastes (1-3). Since concentrated sunlight contains a considerable quantity of near-UV photons (X. > 300
 nm) that can be used to initiate photochemical reactions, as well as infra-red (IR) photons that can serve as a
 source of considerable thermal energy, the solar induced thermal/photolytic destruction of hazardous organic
 wastes appears to be technically feasible.

        Our initial laboratory studies using simulated, broad-band, solar radiation (filtered xenon arc emission) in
 conjunction with a thermoelectrically heated flow reactor have clearly shown that the destruction rates of target
 compounds can be significantly increased and the production of stable reaction intermediates reduced as
 compared to identical thermal exposures (1,2). We have developed relatively simple global kinetic and
 photochemical models that empirically describe the experimental results. However, the details of the
 photochemistry and spectroscopy are poorly understobd and the need for further investigation is clear. In this
 paper, we present the results of a detailed study of the high-temperature photolysis of chlorobenzene in a gas-
 phase, oxidative environment using a new flow reactor system utilizing a pulsed, tunable laser system as the near-
 UV photon source.
        The experimental portion of this research program was conducted on two dedicated instrumentation
systems. Absorption spectra were obtained on a system referred to as the High Temperature Absoiption
Spectrophotometer (HTAS), while the reaction data was taken with a system called the Advanced
Thermal/Photolytic Reactor System (ATPRS).      •

        The HTAS consists of a specially designed high-temperature absorption cell illuminated by a deuterium
lamp, with the absorbed radiation dispersed by a 0.25'M monochrometer and detected with a 512 channel optical
multichannel analyzer. Temperature dependent absorption spectra were obtained up to 750°C.

        The ATPRS is a modular instrument comprised of a tunable pulsed laser illumination system, high
temperature reactor, and dedicated analytical systems.  The tunable pulsed laser system consists of a Nd:YAG
laser (Continuum, Model 682-20) coupled to a dye laser (Continuum, Model TDL-51). The reactor is a slender
cylinder measuring 4 mm by 250 mm.  Downstream of the reactor is a cryogenic trap that is cooled to -160°C

using chilled nitrogen.  For analysis, the exhaust gases are purged to an in-line programmed temperature GC
(Hewlett-Packard, Model 5890) fitted with a hydrogen flame ionization detector and a mass selective detector
(Hewlett Packard, Model 5970) which was operated in a scanning mode. During normal operation the GC is fitted
with dual columns for simultaneous mass spectrometric (GC/MS) and hydrogen flame ionization (GC/FID)
detection of the effluent from the cryogenic trap.  Alternatively, for analysis of light species (e.g., carbon
monoxide, methane, etc.), the GC was operated as a conventional system using gas samples collected in Tedlar
bags attached to the cryogenic trap's exhaust port.
        Figure  1 presents data on the thermal and thermal/photolytic destruction of chlorobenzene. As can
readily be seen by comparison of theseFigures, the rate of destruction of chlorobenzene is accelerated with the
addition of ultra-violet radiation. Furthermore, fewer (and different) products are formed following
thermal/photolytic treatment that are decomposed a lower temperatures than the products formed under purely
thermal degradation conditions.

        The photochemical quantum yield for chlorobenzene destruction was calculated to achieve a maximum
of 0.536 at 700°C and the destruction of chlorobenzene was also enhanced by a factor of 4300 at this temperature.




! ^
Chloribenzent //7>K
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l-HetliDl-noplitholtnt / // /Ifti
l-Prcpengl-benzent /' // f,\\ In'
2-Chloroptienol // /.' BS
3-Chlorophenol // /If ?li
: (tcenaphtholene // '/| It
^ Benzeoe ; I , 1 i, '1
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, '
   300       m       m      600
                  ExposureTeuperoture, C
3M       1M       SN      fM
                fxpnvt Tetperttwi, C
Figure 1. Comparison of product yields from the thermal and thermal/photolytic oxidation of monochlorobenzene
at I0 - 883 mW/cm2 @ 280 nm. [ClBz]0 = 2.95 x 10'5 mol/L.  R.T. = 10.0 s.  Of particular note is the reduction
in quantity, yield, and stability of the thermal/photolytic by-products. Significantly, this is an apparent change in
oxidation mechanism resulting in different products.

        Data on this and other compounds demonstrate the potential viability of destruction of toxic wastes using
concentrated solar radiation.                    ;

        There appears to be several advantages of solar destruction over thermal destruction which include:

        1.  Increased destruction efficiency of the parent and by-products;
        2.  Control of vaporization of toxic metals through lower operating temperatures;
        3.  Control of NOX formation through lower operation temperatures;
        4.  Recovery of excess thermal energy that can be used for thermal desorption
            of solids and sludges;
        5.  Control of CO, CO2, and toxic organic emissions through substitution of solar
            energy for conventional fuels;       j
        6.  Cost savings due to lower fuel costs, increased materials lifetime, and reduced size
            and complexity of air pollution control devices;
        7.  Increased public acceptance through iise of a renewable, non-polluting
            energy source for a non-incineration waste disposal technology.

        Apparent major disadvantages include:

        1.  The unreliable availability of solar radiation;
        2   Cost of collection and concentration Of solar radiation;
        3.  Lack of an off-the-shelf technology to construct a working pilot-
            or full-scale system.

Our task is to develop an approach that utilizes the advantages and to minimize the disadvantages.

        One approach that has been previously proposed is to develop a hybrid two-stage system targeted for
detoxification of contaminated soils and other solids [3]. With this concept, a hybrid primary unit (possibly an
indirectly-fired rotary drum design) may  be used to thermally desorb organics from solids, while a secondary solar
reactor would be used to thermal/photolytically destroy the desorbed organics. An auxiliary heat source is
necessary to operate the process continuously during intermittent cloud cover and maintain night-time operation.
The desorbed organic matter during dark operation may be stored by cryogenic trapping or sorption on carbon for
destruction during light periods. Since the total volume of material desorbed is small, the photolytic reactor
should readily handle the stored off-gases during light operation. This approach maintains the previously listed
advantages for solar based waste destruction while minimizing two of the three disadvantages.  The hybrid
primary unit allows continuous operation, thus eliminating the concern over the unreliability of sunlight.

1.    Graham, J. L. and Dellinger, B. Solar Therinal/Photolytic Destruction of Hazardous Organic Wastes.
      Energy, 12, No. 3/4, pp . 303-310,1987.

2.    Graham, J. L., Dellinger, B. and Klostermaii, D., Glatzmaier, G., and Nix, G., Disposal of Toxic Wastes

      Using Concentrated Solar Radiation. In: Emerging Technologies in Hazardous Waste Management II,
      American Chemical Society, Washington, DC, Chapter 6,, April 1991, pp. 83-104.
3.     Bellinger, B., Graham, J. G., Herman, J. M., and Klosterman, D. High Temperature Photochemistry
      Induced by Concentrated Solar Radiation. In: Proceedings of the National Academy of Sciences on
      Potential Applications of Concentrated Solar Photons. Solar Research Institute. National Research
      Council. 1990.

                               Gregory J.  Carroll
                      U.S.  Environmental  Protection Agency
                     Risk Reduction Engineering Laboratory
                             Cincinnati,  Ohio 45268

                                Johannes W. Lee
                               Acurex Corporation
                           Jefferson,  Arkansas  72079

     As part of their permitting process, hazardous waste  incinerators must
undergo demonstration tests, or "trial burns", during which their ability to
meet EPA performance standards is evaluated.  Among the performance standards
is a minimum destruction and removal efficiency  (ORE) for  principal organic
hazardous constituents  (POHCs) in the incinerator waste feed.

     In accordance with the regulations promulgated under  the Resource
Conservation and Recovery Act (RCRA), selection  of POHCs for incinerator trial
burns is to be based on "the degree of difficulty of incineration of the
organic constituents in the waste land on their concentration or mass in the
waste feed." (I)  In order to predlict the relative difficulty of incinerating
specific compounds, several "incinerability" ranking approaches have been
proposed, including a system based on POHC heats of combustion and a system
based on thermal stability under pyrolytic conditions. (£)
     The latter ranking system was'developed by  the University of Dayton
Research Institute (UDRI) under contract to the  U.S. EPA Risk Reduction
Engineering Laboratory  (RREL).  The system is supported largely by non-flame,
laboratory-scale data and is based on kinetic calculations indicating that
post-flame pyrolysis of poorly-mixed waste/air pockets is  the primary
contributor to emissions of undestroyed organic  compounds. (2-4)  The subject
tests were conducted to develop data on POHC behavior in a larger-scale,
conventional incineration environment.


     Testing took place in the rotary kiln incineration system (RKS) at the
U.S. EPA Incineration Research Facility (IRF) in Jefferson, Arkansas.  The RKS
consists of a primary combustion chamber and a secondary (afterburner)
chamber.  Flue gas exiting the afterburner flows through a quench section,
which is followed by a venturi scrubber and a packed-column scrubber.
Downstream of the packed column is a secondary air pollution control system
(APCS) consisting of a demister, activated-carbon adsorber, and a high-
efficiency particulate filter.    >

       Mixtures  of 12  POHCs,  consisting  of compounds  from  each  of 7  proposed
 incinerability  classes,  were formulated for  the  tests.  Table  1  lists  the  test
 compounds  in  decreasing  order of predicted thermal stability.

      Feed  batches,  consisting of 3  Ib of POHC mixture  added  to 5 Ib of a clay
 adsorbent  material, were fed to  the kiln in  1.5  gal  fiberpack-containers.
 Compound concentrations  in Mixture  #1 (Tests 1,  2, and 3)  ranged from  8 to 10%
 by weight, with the exception that  n-nitroso-di-n-butylamine was present at
 only  2% for safety  reasons.   POHC concentrations in  Mixture  #2 (Tests  4 and  5)
 were  tailored to achieve the desired hydrogen/chlorine ratio.

      Five  kiln  operating modes were investigated: a  baseline condition; 3
 failure modes (thermal,  mixing,  and matrix); and a worst-case  combination  of
 the 3  failure modes.  Target conditions for  key  test parameters  are indicated
 in Table 2.

      Permit restrictions and health and safety concerns precluded operating
 the entire system (kiln,  afterburner, APCS)  under failure  mode.  Therefore,
 failure mode  operation was attempted in the  kiln only and  it was the kiln  exit
 (as opposed to  the  stack) at which  flue gas  POHC concentrations  were measured
 in order to determine relative DREs. (J5)


     No semivolatile POHCs were  detected  in the  kiln exit  gas  during Test  1
 (baseline), Test  3  (mixing failure), and  Test 4  (matrix failure).   Only low
 levels of volatile  POHCs were observed  in  these  3 tests.   In contrast, Test  2
 (thermal failure) and Test 5  (worst-case) yielded detectable levels of 3 of
 the 7  semivolatile  POHCs  and  significant  levels  of all 5 volatile POHCs.

     Table 3  presents kiln-exit  POHC DREs  for each test.  A  "greater than" ORE
 in the table  indicates that  the  POHC was  not detected in the kiln-exit flue
 gas for that  test.  The  lower ORE limit  in such  cases is calculated using  the
 practical  quantitation limit  (PQL)  for  the POHC  in the exit  gas.   Since the
 exact  POHC concentration may  be  anywhere  between zero and  its  PQL,  the exact
 POHC ORE may  be anywhere between this lower bound and 100%.

     In the following discussions,  "incineration failure" refers to poor
 destruction of  POHCs in the  kiln, resulting in low (less than 99.99%) kiln-
 exit DREs.   As  expected,  incineration failure does not appear to have taken
 place during  the  baseline operating conditions.   Likewise, the attempts to
 achieve incineration failure  in Test 3  (mixing failure) and Test 4  (matrix
 failure) appear to have fallen short.  DREs during each of those three tests
were uniformly  above 99.99%.   The close distribution  of DREs among the POHCs
makes identification of a correlation between predicted and observed POHC
ranking extremely difficult.   Interpretation  of the data is further
complicated by the fact that kiln-exit concentrations of 7 of the POHCs Were
below their PQL.  While it may be said that DREs for  those POHCs  are "greater
than VX%'", their exact values are not known.

                     TABLE  1.  POHC  MIXTURE  COMPOSITIONS
                Concentration (wt %}

              Mixture 1        Mixture 2
  (Freon 113)
  hexane (Lindane)
  1,1,1-Tri chloroethane
  Diphenyl disulfide
  benzene (Methyl yellow)










Temperature required to achieve 99% destruction in 2 sec under
pyrolytic conditions; based on experimental, laboratory studies of
mixtures (4)                    ,
                      TABLE 2.  TARGET TEST CONDITIONS


Feed (Ki
temperature ;
[°C (°F)] [molar]
weight Charges/

Includes 0.9 kg (2 Ib) water added.

                       TABLE 3. KILN-EXIT POHC DREsa (%)
Tetrachl oroethene
Freon 113
Diphenyl disulfide
Methyl yellow
Test 1
>99. 99969
>99. 99969
>99. 99922
>99. 99969
>99. 99969
Test 2
(thermal )
>99. 99901
>99. 99961
>99. 99961
Test 3
>99. 99957
>99. 99966
>99. 99966
>99. 99914
>99. 99966
>99. 99966
Test 4
>99. 99909
>99. 99928
>99. 99986
>99. 99928
>99. 99928
Test 5
* Based on feed formulation data.
  ">" indicates POHC not detected in kiln exit gas; lower-bound ORE computed
   using PQL.

     Tests 1, 3, and 4 did yield measurable emissions of the 4 POHCs which
were predicted to be most difficult to destroy.  As would be expected, this
resulted in lower DREs for those POHCs than for the majority of the other
POHCs.  Among the more significant anomalies was 1,1,1-trichloroethane, which
sometimes had measured DREs substantially lower than similarly-ranked POHCs.
This may be due to the fact that 1,1,1-trichloroethane is a common product of
incomplete combustion (PIC), and can be reformed during the incineration

     Incineration failure does appear to have taken place during the thermal
failure and worst-case modes (Tests 2 and 5).  Low to moderate DREs were
quantifiable for 8 of the 12 POHCs in those two tests, and the 4 POHCs not
detected are those predicted to be the easiest to destroy.  In contrast to the
1,1,1-trichloroethane discussion above, the unexpectedly-low ORE for Freon 113
in Tests 2 and 5 cannot be explained by PIC formation.  Nonetheless, despite
the fact that the four predicted most-difficult-to-destroy compounds did not

 follow the  expected rank order in  tests  2  and  5,  a  strong  correlation  with  the
 ranking system predictions  exists  for the  two  tests.  (5)

 CONCLUSIONS                       I

     As discussed  above,  each  of the  tests yielded  emissions  of  some POHCs  at
 concentrations below their  PQLs.   This presents a challenge  in that the  exact
 DREs for such  compounds  are essentially  unknown;  they  are  greater  than the
 DREs computed  using the  PQLs.   As  a result of  the unknowns,  exact  ordering  of
 observed POHC  ranking is  not possible.   This was  the case  with diphenyl
 disulfide,  methyl  yellow, nicotine and n-nitroso-di-n-butylamine during  each
 of the five tests,  and with nitrobenzene,  lindane and  hexachloroethane during
 Tests  1,  3  and 4.                  !
     In order  to evaluate how  well the observed POHC incinerability ranking
 order  correlated with that  predicted  by  the UDRI  ranking system, a statistical
 test was applied to the data.   The:Spearman rank-order coefficient provides a
 measure of  the confidence with which  it  can be stated  that a  statistically-
 significant correlation exists.    i

     Because the exact DREs for several  POHCs  are unknown, discrete rank-order
 coefficients could  not be determined.  Rather, ranges  of coefficients  based on
 assumed DREs were  computed.  Best-case assumptions  suggest that a
 statistically-significant correlation  at the 99%  confidence level between the
 predicted and  observed ranking orders may  exist for each of the five tests.
 If one  were to adopt  the worst-case assumptions,  the correlation between
 predicted and  observed orders  would be below the  90% confidence level  for
 Tests  1, 3,  and 4.   However, it  can be concluded  with  certainty that
 statistically-significant correlations exist for  Test  2 and Test 5 at  the 99%
 and 95% confidence  levels,  respectively, even under the worst-case scenario.
 REFERENCES                         j

 1.    Code  of  Federal  Regulations; iTitle 40, Part 264, Subpart 0.

 2,    Guidance on Setting Permit Conditions and Reporting Trial Burn Results:
      Volume II of  the Hazardous Waste Incineration Guidance Series.
      EPA/625/6-89/019, U.S. Environmental  Protection Agency, 1989.

3.    Dellinger, B.,  P. Taylor, and D. Tirey.  Minimization and Control of
      Hazardous Combustion  Byproducts. EPA/600/52-90/039, 1991.

4.    Taylor,  P., B.  Dellinger, and C. Lee.  Development of a Thermal-
      Stability-Based  Ranking  of Hazardous Organic  Compound Incinerability.
      Environ.  Sci. Techno!..  Vol.  24, No.  3, 1990.
5,    Lee, J.,  W. Whitworth, and L. Waterland.   Pilot-Scale Evaluation  of the
      Thermal Stability POHC Incinerability Ranking - Draft Test Report.
      U.S.  Environmental  Protection Agency Contract No. 68-C9-0038, 1991.

                     J.H.J. Thijssen, M.A. Toqan, A.F.S. Sarofim, andJ.M. Beer

                       Dept of Chemical Engineering and Energy Laboratory

                              Massachusetts Institute of Technology

                                   60 Vassar Street 31-261

                                    Cambridge, MA 02139

                                     Tel. : (617) 253 0876

In the continuous monitoring of trace combustibles we are presented with two fundamental problems:
there are too many trace combustibles regulated to be able to practically monitor all those compounds
individually in real time, and the control of the combustion and incineration devices according to hundreds
of parameters would be impractical. Therefore, surrogates, that can be easily monitored, are necessary to
represent the concentrations of large groups of those trace combustibles. Traditionally, carbon monoxide
has been used for this purpose because of its role in the final oxidation step of all hydrocarbons. However,
it has been found frequently, that CO concentrations measured correlate poorly with concentrations of air-
toxics obtained from stack sampling. This is plausible if one realizes that the critical role of CO presumes
that the trace combustibles should remain reactive to the point of sampling. However, when trace
combustibles escape to low temperature regions of the combustion system (eg. because of poor mixing),
oxidation rates might become so low that the trace combustibles become largely unreactive, not forming
any CO in the process. Thus the trace combustibles might go undetected by the surrogate monitoring

It was thus proposed that surrogates are measured which are more chemically similar to  the trace
combustibles and which are equally, or preferentially more, refractory than the trace combustibles. PACs
were found to be very refractory to oxidative destruction and they can be measured in low concentrations
in real time (1). In experiments being carried out the use of PACs as surrogates for trace combustibles
emissions is compared to the use of CO for that purpose. In the experiments the formation and •
destruction of PACs, as well as of CO, is studied in detail in a turbulent natural gas diffusion flame which is
doped with an aromatic compound (toluene). CO measurements are made using a conventional CEM
apparatus, and PACs are monitored by means of the MIT laser induced fluorescence (now LIF) system
which has  been developed under a separate project(2), and characterized in detail by a physical sampling
method described elsewhere.


All combustion experiments are carried out in the M.I.T. Combustion Research Facility (CRF), a tunnel
furnace with a maximum thermal input of 3.0 MW. The CRF consists of a number of separate, water cooled,
sections, a variable number of which may be refractory lined on the inside. It is equipped with a Variable Swirl
Burner (VSB) which allows the flow and mixing pattern in the near burner region to be controlled.

 Secondary ("overfire") air can be introduced through a, separate, secondary air injection section and
 dopants may be injected through probes. The pRF allows both physical and optical access to the
 horizontal plane of symmetry through ports in all sections. For the experiments described in this paper the
 CRF was configured as shown in Fig. 1. A detailed description of the MIT CRF is given in Beer et at2.

 All fluorescence experiments are done using the LIF/LLS system depicted in Fig. 2. The excitation source
 is a 5 W (multi line) argon ion laser, operated at;its 488 nm line. The laser beam, modulated (at 1000 Hz) by'
 a light chopper, is directed to the sampling volume by two beam steerers. A sampling volume, of 2 mm
 diameter and 60 mm length, is observed by the detection system which consists of a single lens, colored
 (OG 515) fitters, a Jarrell Ash 25 cm focal length monochromator (with a stepper motor wavelength
 selector) and an EMI 9558 QB photomultiplier tube, thermoelectrically cooled to 263 K. The PMT output is
 collected by an EG&G 5105 lock-in amplifier, tjjned to the chopper reference frequency. An IBM PC/AT
 serves for data acquisition and process control The attenuation of the laser beam by the flame, necessary
 for correction of the LIF signal, is determined by the use of a power meter in the port opposite to the LIF
 instrument.                               I

 In the combustion experiments, no windows are used to avoid effects of fouling, inevitably associated with
 windows. The furnace, under normal operation^ is operated with a slight underpressure, so as to avoid
 possible damage to the optical equipment by Combustion fluctuations. Due to the underpressure, and the
 favorable geometry of the power meter (narrow view angle), there is no observable effect, of the radiation
 from the flame upon the measured signal.
 Physical samples from the CRF are drawn through a stainless steel water cooled probe into a
 Dichloromethane (DCM) Sampling system, consisting of two refrigerated baths of DCM in series (243 K
 and 203 K respectively) in which the PACs are to be dissolved. The DCM sample (with the PACs),
 including the amount used for rinsing the probe,  is-concentrated by Kuderna Danish evaporative
 concentration and analyses by HPLC-UV, GC-FID and GC-MS(SIM)


 In all experiments, the fire box is run at a near stoichiometric fuel  equivalence ratio.  Secondary fuel, in the
 form of a monocyclic aromatic compound, in particular toluene, is added in the entrance of the cylindrical
 section. This fuel has a small concentration (order of 102 ppm), so that the fuel equivalence ratio is only
 marginally affected. Secondary air,  to yield an oxygen mole fraction of --0.06, is injected in the cylindrical
 section to oxidize the PACs formed.
                                          i                                 '
 Test are run with equal amounts of the secondary fuel injected, as well as one blank test, in which no
 secondary fuel is injected at four different temperatures (in the range between 1400 and 2000 K). In each
 test detailed measurements are made of temperatures, velocities, and major species and trace
 hydrocarbon species, along all axial center linelstations of the furnace in both fuel rich and fuel lean zones
 of the combustion system.                  :

Those measurements illustrate the processes by which PACs, trace combustibles, and CO are being
formed and destroyed and thus the propensity of both PACs and CO as surrogates for trace combustibles
can be assessed from a fundamental point of view.


1.     J. M. Beer, W. F. Farmayan, J. D. Teare,  M. A. Toqan, (Electric Power Research Institute, 1985),

2,     J. H. J. Thijssen Toqan, Majed A., Beer,, Janos M., Sarofim, Adel F., in Second International
        Congress on  Toxic Combustion By-Products: Formation and Control R. Seeker Koshland, C.,
       Eds. Salt Lake City, Utah, U.S.A., 199t),

                                          primary air

1 i
T5I fire box _
ri n

iii iii

III 1 1


                    i  i
                            sampling ideations

         Figure 1 : configuration of the MIT CRF
to stack
                                           _X	monochromator

                                       5 W argon laser
power meter                                            chopper

                  Figure 2 : Schematic of the MIT LIF System


                                     William J. Cooper1
                                     Thomas D. Waite2
                                     Charles N. Kurucz3
                                    Michael G. Nickelsen1
                                         Kaijun Lin1
                               1 Drinking Water Research Center
                                Florida International University
                                      Miami, FL33199
                                      .(305) 348-3049

                       2 Department of Civil and Architectural Engineering
                                     University of Miami
                                   Coral Gables,  FL 33124
                                      (305) 284-3467

               3 Department of Management Science and Professional Engineering
                                     University of Miami
                                   Coral (Sables, FL 33124
                                      (305) 284-6595
       As a result of the widespread presenbe of hazardous organic contaminants in aqueous
matrices, considerable research is being conducted on treatment technologies for removing these
compounds from contaminated environments.  Historically treatment process efficiency focused
only on the removal of the solute of interest Ifrom solution, with little or no concern for the
formation of potentially hazardous reaction by-products. An extension of this approach is the use
of carbon adsorption and aeration stripping. In the case of carbon the solutes are concentrated and
then incinerated during the carbon regeneration  process. Aeration stripping for the removal of
volatile chemicals at worst transfers the problem directly into the atmosphere and at best transfers
it to carbon or another adsorbent.

       A more realistic approach to the problem of the disposal of toxic and hazardous organic
waste chemicals will be the development of treatment processes that result in, or facilitate, the
mineralization of the chemicals. Probably the best known process to achieve this is the use of
ozone, O3, most often in the presence of various catalysts for its decomposition, e.g. ultraviolet
(UV) light and/or hydrogen peroxide, H2O2.  Other chemical/physical processes that are receiving
attention are supercritical oxidation and wet oxidation.  Bioremediation can also be considered an
ultimate disposal process. Incineration of wastes has certain demonstrated advantages, but also a
high potential for the formation of reaction  by-products that may be as bad or in some instances
worse than the starting materials.

       The current innovative treatment process being evaluated is the use of high energy
electrons for the ultimate disposal of hazardous  organic contaminants from aqueous matrices.
When high energy electrons impact an aqueous  solution reactive transient  species are formed. The

three transient species of most interest, in the removal of hazardous contaminants from aqueous
matrices, are the aqueous electron, e"«,, the hydrogen radical, H-, and the hydroxyl radical, OH-.

       This paper describes the use of high energy electrons for the destruction of chloroform,
trichloroethylene (TCE), tetrachloroethylene  (PCE), benzene, toluene, and phenol from aqueous
solution. The experimental parameters examined are: absorbed dose, water quality (with and
without the addition of 3% clay), and carbonate ion concentration.
       The Electron Beam Research Facility (EBRF) is located at the Miami-Dade Central District
Wastewater Treatment Plant located on Virginia Key, Miami, Florida. The facility consists of a
horizontal 1.5 MeV insulated-core transformer (ICT) electron accelerator capable of delivering from
0 to 800 krads absorbed dose.  The electron beam is scanned at 200 Hz to give a coverage of 48"
wide and 2" high.

       Influent streams at the EBRF are presented to the scanned beam in a falling stream
approximately 48" wide and at the design flow of 120 gpm is 0.15" thick.  Total power
consumption,  including pumps, chillers and other auxiliary equipment is about 120 kW.

       The experiments presented in this paper were conducted by preparing 3,000 gallon (11,355
L) solutions of the compounds slated for study in either a 4,600 or 6,000 gallon tanker. The
tanker is then directly connected to the influent of the EBRF, where the solution is pumped and
irradiated.  All contaminants were studied at 0.1,  1.0, and  10 mg L1, pH 5, pH 7 and pH 9, with
and without the addition of 3% clay.
        Initial results using high energy electron radiation were presented at the 17th Annual RREL
Research Symposium.  By changing the experimental design and eliminating the use of methanol,
as a carrier for the organic contaminants studied, we have begun to develop a better understanding
of the removal processes and more realistic estimates of removal efficiency than previously

        Tables 1 -3 summarizes the calculated d0 B0, d0.90, and d0.a9 values for TCE with and without
the addition of 3% clay at three different pH levels.  That is, the absorbed irradiation dose required
to remove 50%, 90%, and 99% of the initial concentration of TCE from solution. From these
results, it appears that our initial removal efficiency estimates were at least 10-fold higher than
when methanol is eliminated from the experimental matrix.  That is, equivalent solute removal is
now possible with about 10-fold less energy. In addition to increased removal efficiency we have
conducted extensive studies on solutions of up to 3% clay and have show that the presence of the
suspended matter only moderately affects removal efficiency and in some instances actually
increases removal efficiency.

        Since  carbonate ion is an excellent scavenger of OH-, the in situ concentration of carbonate
ion was controlled by pH adjustment.  For trichloroethylene and tetrachloroethylene lowering of the
pH (i.e., less available carbonate ion) did not seem to enhance removal efficiency. This is because
these halogenated compounds are primarily removed by e'^,.  Chloroform, however, did show a

 decrease in removal efficiency at lower pH values.  This is opposite from what was expected.  At
 this time the reason for this phenomenon is unknown.  For the aromatic compounds benzene,
 toluene, and phenol removal efficiency was enhanced by pH adjustment.  This is attributed to the
 lower carbonate ion concentration available at lower pH values. That is, less OH- scavenging by
 carbonate ion.                             \

        Reaction by-products identified for a majority of the compounds studied included: chloride
 ion, low molecular weight aldehydes and low molecular weight carboxylic acids. All organic
 reaction by-products were identified in sub-micromolar concentrations.  From these results it
 follows that the remaining concentration of starting material was completely mineralized to halide
 acids, carbon dioxide, and water.
        In conclusion, the use of high energy electrons appears to be a promising treatment
technology for the ultimate destruction of hazardous contaminants from aqueous matrices.  This
innovative treatment technique has the ability:to completely mineralize a variety of hazardous
compounds without the added problem of a secondary treatment technique for ultimate
contaminant disposal as in carbon adsorption iand/or aeration stripping.  Furthermore, high energy
electron radiation has demonstrated the destruction of these hazardous contaminants in a variety of
water qualities ranging from treated groundwgter to water containing up to 3% suspended solids.
Kurucz, C.N., T.D. Wait, W.J. Cooper and M.C3. Nickelsen.  Full-Scale Electron Beam Treatment of
Hazardous Wastes - Effectiveness and Costs in Proceedings of the 45th Annual Purdue University
Industrial Waste Conference. Lewis Publishers, Inc., 1991, pp 539-545.

Kurucz, C.N., T.D. Waite, W.J. Cooper and M.G. Nickelsen.  High-Energy Electron Beam Irradiation
of Water, Wastewater and Sludge, in Advances in Nuclear Science and Technology. Volume 23, J.
Lewins and M. Becker, Eds., Plenum Press, N.Y. N.Y., 1991  (in press).

Nickelsen, M.G., W.J. Cooper, T.D. Waite, an
 Table 1.   Summary of the Doses Required to Remove 50%,  90%,  and 99% of TCE From
           Aqueous Solution.
Table  2.  Summary of the Doses Required  to Remove  50%,  90%,  and  99%  of TCE From
          Aqueous Solution.
                                    Target at 7.62 fitt (1,000 ng/L)
Table 3.  Summary of the Doses Required to Remove 50%, 90%, and 99% of TCE From
          Aqueous Solution.
                                   Target at 76.2
   5  Rep #1
     Rep #2
   7  Rep  #1
     Rep  #2

                                       Thomas J. Powers
                              Risk Reduction Engineering Laboratory
                  Office of Environmental Engineering Technology and Development
                               Office of Research and Development
                          United States Environmental Protection Agency
                                26 West Martin Luther King Drive
                                     Cincinnati, Ohio  45268
                                 Phone Number:  (513) 569-7550
       Cleaning of contaminated surfaces presents many challenges. Surfaces can be cleaned in many
 ways and, depending on the cleaning method,;produce many waste by-products.  Many of the wastes
 produced will be hazardous or toxic and therefore require proper containment, capture and disposal.
 One cleaning or surface preparation method is, blast finishing. Blasting technology is not new.  Within
 the past two decades, modified or specialized blast media have been selected to enhance the surface
 cleaning and preparation process. Older methods utilize natural abrasives such as water and sand.
 The newer methods employ glass beads, steel shot, steel grit, aluminum oxide, silicon carbide, garnet
 grain, walnut or pecan shells and plastic beads to create variations in abrasive action.

       A ranging study was conducted to determine the applicability of pelletized carbon dioxide as a
 media for removal of lead-based paint from wooden doors, and to characterize the occupational
 exposures to airborne lead and total particulate.  Personal breathing zone and work area samples were
 collected to  assess the airborne concentrations of lead particulate.  Aerodynamic particle size
 distribution were determined using Marple Series 290 Cascade Impactors.  Residual surface levels of
 lead were determined using the   Housing and Urban Development (HUD) wet-wipe method and a
 particulate adhesive sampler (PAS).


       The blast cleaning of surfaces is an art form which has been used throughout industry as a quick
 and highly efficient method of surface preparation for coatings or reuse.  Certain applications have
 become more sophisticated due to environmental constraints. As a result of these considerations,
 containment systems and pollution recovery systems are expected.  Current  regulations in many states
 require adequate capture and disposal of blasting sand that has been used to clean chromium, lead or
 other coating materials.                     '         .            •

      The use of carbon dioxide as a blast media, can offer several advantages over other materials
 and methods.  One positive feature of using CO2 is the reduced volume of solid and liquid waste
 requiring disposal. A fifty to one  ratio is not uncommon.  A second favorable feature  is that the surface
finish of metals may  not be altered; if desired, the degree of removal may be tailored so that original
 undercoat is left and thus remains for refinishing.  One disadvantage to the use of this process is the
 CO2 level in the work area may be high and a second drawback would be that while CO2 pellets
 remove most rust, sand or some other abrasive media; blast may be required to meet current paint
 preparation specifications related to profiling and "white metal" surface.

      A video dramatically presents the blasting cleaning process using pelletized CO2. This video
explains applications which  have a proven performance history.  Carbon dioxide surface cleaning can
be an effective method if it is applied properly.

       Each cleaning process has five factors for evaluating the effectiveness of cleaning contaminated

       1. Surface to be cleaned,

       2. Penetration of cleaning agents,

       3. Type of contamination to be removed and disposed of,

       4. Disposal method, and

       5. Total cleaning cost.

       The cleaning process can be physical/mechanical or chemical or a combination of both.
 Common physical/mechanical methods include polishing, sanding, grinding and blasting. The chemical
 methods typically are acids, alkalies, solvents, and water.  Almost any combination can be used in a
 variety of sequences to produce the desired effect.

       The most common surfaces to be cleaned are metals,  concrete, plastic, fabrics, and wood.
 These surfaces may be contaminated with benign compounds, unknown substances, toxic substances,
 hazardous wastes, and radioactive substances.

       The factors for evaluating the effectiveness of cleaning  a surface will depend upon:

       1. Thickness of contaminant,

       2. Penetration of the substrate

       3. Bonding characteristics,

      4. Required reaction, and

       5. By-products.

A good cleaning process requires surface decontamination, sub-surface removal,  preparing the surface
for sealant and proper collection and disposal of residues. Surface cleaning methods available should
include but not necessarily be limited to, 1) mechanical wipe, 2) chemical wipe/rinse, 3) physical
abrasion, 4) chemical penetration, and 5) penetration by mechanical means. The selection of abrasive
cleaning agents will depend upon the surface contamination, hardness of surface, and blasting material
hardness.  The blasting process can be both a cleaning and  a finishing method.  Blasting can remove
surface contamination and roughen the surface for the application of paint. Blasting is also used to
remove surface irregularities and create a specific surface finish.

      The CO2 process utilizes pelletized carbon dioxide, which is metered into an air stream on
demand. This air stream is then directed through a nozzle at  high velocity and the solid  CO2  particles
impinge on the article to be cleaned. The collision between pellets and the work piece causes the
kinetic energy of the pellets to be rapidly converted to heat which causes the CO2 to sublime.

      The cleaning effectiveness of carbon dioxide pellets relative to the substrate being cleaned is
determined by:

      1. Composition of substrate         [

      2. Mass and density of CO2 pellets   !

      3. Velocity of CO2 pellets

      4. Dwell time of CO2 pellets

      5. Angle of impact
      6. Temperature of the surface        ',

      7. Distance between nozzle and surface to be cleaned.

The proven applications of carbon dioxide cleaning include material preparation, technical cleaning,
paint removal, and decontamination.         \


      The ranging study conducted on lead paint removal from wood doors revealed some very
important aspects of using the pelletized CO2 process:

      1.   Personal breathing zone and work area concentrations respectively, were approximately 2
           and 4 times the OSHA Permissible Exposure Limit (50 (xg/m3) for lead during removal of
           lead-based paint from wooden doors.  Work area sample concentrations are higher than
           the personal breathing zone concentrations because they represent concentrations
           measured closest to the point of generation of the participate (i.e.r the samples were
           positioned approximately 2 feet from the workpiece).
                                         i                                 '
      2.   Cascade Impactors were used to determine the cumulative particle size distribution of lead
           and total paniculate aerosol. The jmass median diameter (MMD) of total particulates for
           two personal breathing zone and two work area samples are 13.5 and 10.5 microns and 28
           and 24 microns, respectively. The MMD of lead for two personal breathing zone and two
           work area samples are 13 and 17imicrons and 38 and 41  microns, respectively.  Particles
           larger than 10 micron equivalent diameter are essentially all removed in the nasal chamber.

      3.   Samples collected for assessing lead-particulate fall-out in the test room showed
           concentrations that ranged from 730 to 1,300 (ig/ft2.

      4.    Residual surface concentrations of lead using the wet-test method ranged from 330 to
           5,000 jig/ft* (average = 3,500 ng/ft2). All but one of these samples exceeded the
           Department of Housing and Urban Development (HUD) interim surface guidelines of 200 to
           800 |ig/ft2. Residual surface concentrations of lead using the tape-lift method ranged from
           84 to 3,800 ng/ft2 (average = 1,320 jig/ft2). Half of these samples were less than the HUD
           interim surface guidelines.

      5.    Baseline concentration of gaseous carbon dioxide in the test room was 1,000 parts per
           million (ppm). Measurements made at approximately 15-minute intervals during the carbon
           dioxide blasting ranged from 2,000 to 30,900 ppm (n = 11, arithmetic average =  10,700
           ppm). By comparison, the OSHA PEL's 10,000 ppm for an 8-hour time weighted average,
           30,000 ppm for a 15-minute short-term excursion limit, and 50,000 ppm for an immediately
           dangerous level to health.

      Sampling and analytical methods used to measure surface cleanliness have been investigated
recently by the Risk Reduction Engineering Laboratory. A dozen sampling methods were investigated
and each technique appeared to have certain advantages. The analytical quantatfoe and qualitative
methods will vary with the type of contamination on the surface.  All of the cleaning procedures require
a surface testing method to determine the appropriate cleaning agents and system to produce the
desired result - a "clean" surface. The question becomes  "how clean is clean?" This can only be
defined using the proper sampling and analytical methods.


      Major conclusions on the pelletized carbon dioxide cleaning process are:

      1.  Selecting proper sequence of methods for each application produces high efficiency.

      2.  Surface testing is a  mandatory requirement for evaluation.

      3.  Several cleaning methods used together may enhance efficiency.

      Pelletized carbon dioxide blasting appears to be a viable technology to remove lead-based paint
from wooden surfaces (e.g., doors).  The removal efficiency of the technology can be enhanced by final
cleaning procedures.  Environmental control systems can be developed to minimize fugitive paniculate
release and gaseous carbon dioxide. This technology can significantly reduce the quantity and nature
of the waste generated during paint removal and produces no liquid waste. Hence, it offers
outstanding environmental gains regarding hazardous waste minimization.


                           Lisa M. Brown
               U.S. Environmental Protection Agency
                   26 W. Martin Luther King Dr.
                      Cincinnati, Ohio  45268
     Used oil and discarded oil filters are a major source of
waste in the U.S.  Two possible ways of minimizing these wastes
are the use of reusable oil filters and the use of filters that
extend oil life.  Reusable filters may reduce waste since they
can be cleaned and reused instead of being discarded.  Filters
that reduce the rate at which engine oil deteriorates in quality,
allowing the oil to be used longer between oil changes without
harm to engine life, generate less oil and filter wastes due to
fewer oil changes.             >

     A oil filter testing program was started in January 1991 as
a part of the California/EPA Waste Reduction Innovative
Technology Evaluation  (WRITE) Program.  The California/EPA WRITE
program is now in its third year of technically and economically
evaluating waste reduction technologies.  The WRITE Program is a
national research demonstration program designed to evaluate the
use of innovative engineering and scientific technologies to
reduce the amount and/or toxicity of wastes generated from the
manufacture, processing, and use of hazardous materials.  This
work was done under a Mission of Support Policy Agreement between
the U.S. EPA and the California Department of Toxic Substances
     In this testing program, three types of diesel engine bus
oil filters (reusable wire mesh, disposable fiber, and disposable
paper) underwent an engineering and economic evaluation at the
Orange County Transit Association (OCTA) in Garden Grove, CA.
The two major objectives of the testing were (1) to assess the
performance of three different types of oil filters and (2) to
determine if the oil life could be extended.  Testing parameters
included efficiency, ease of use, economics, and environmental
impacts, such as the reduction of number of oil filters and/or
the frequency of oil changes.
METHODOLOGY                    '.

     This program was designed !to test alternative filters on
twelve OCTA fleet buses with Detroit 6V92T diesel engines.  The
twelve test buses selected were identical in manufacturer and age
and were dispatched from the same division.  The buses were as
similar as possible in mileage, type of service route, and
previous routine oil analysis results.  Three sets of buses were
grouped at random; each set included four buses with identical
primary filters and secondary centrifugal filters.  Four buses


were the baseline test vehicles with regular spin-on pleated
paper primary filters.  The second set of four buses were
equipped with a composite synthetic media primary filter.  The
third set of buses used a reusable screen for the primary filter.

     During the 4-month test period the twelve selected buses
were sampled weekly each Saturday between the dates of May 18
through September 21, 1991.  On each bus a special device was
installed that allowed extraction of a sample of the circulating
oil.  A brass fitting called a "probalyzer" was installed on the
oil recirculation line downstream from the primary filter.  The
fitting had an internal valve that could be opened to access the
flow of oil while the motor was running.  The oil samples were
analyzed weekly for a series of physical and chemical properties.
These parameters Were used as a tool to monitor and evaluate the
adequacy of the motor and engine oil.  In addition, biweekly
particle counting tests were conducted on the samples in an
attempt to gauge the particle removal efficiencies of the

     Data were analyzed for the following parameter groups:

1.  Wear elements - Iron, Chromium, Lead, Copper, Tin, Aluminum,
     Nickel, Silver, Manganese, Antimony, Cadmium, Titanium
2.  Contaminants - Silicon, Boron, Sodium
3.  Additives - Magnesium, Calcium, Barium, Phosphorus, Zinc,
4.  Physical and Chemical Parameters - Flash point, Fuel,
     Viscosity, Water content, Percent solids, Glycol, Soot, TEN
5.  Particle Counts - >5, >10, >15, >25, and >50 urn

     Test parameters can be grouped into those that primarily
reflect the quality of the oil and those that are indicative of
potential engine problems.  Viscosity and percent solids indicate
oil quality.  Metallic wear elements, water content, glycol
content and contaminants are indicators of potential engine
problems.  These parameters were monitored based upon guidelines
provided by the Detroit Engine Company.


     Overall, no differences could be observed among the twelve
buses except for wear metals and particle counts <25 urn.  Samples
from the buses with synthetic fiber filters had slightly higher
metal concentrations than those with other filters due to one bus
that had consistantly higher concentrations throughout the test.
Samples from these buses also had the lowest concentrations for
particles with diameters <25 urn.  These buses were followed by
the buses with reusable filters, then by buses with regular
filters.  In addition, all of the buses went beyond the 6,000
miles oil filter change limit currently in place by OCTA.  Ten of
the twelve buses operated the full 4-month period without an oil
and filter change.  Miles traveled ranged from 14,429 miles to
21,571 miles.



      Using conventional oil test methods  (excluding particle
 count analyses)  no significant differences were  observed in
 recirculating oil quality between the reusable and  non-reusable
 filters.   With regard to partiple count,  the  composite  synthetic
 media filters maintained significantly lower  particle counts for
 particles  less than 25 urn in sjize than the other two filters.
 Considering the pleated paper filter versus the  reusable filter,
 the  reusable filters showed better performance for  the  particles
 <25  urn.  The differences in performances  between filters
 disappeared as particle sizes -Increased.

      Oil and filter changes at OCTA  are currently performed
 approxiamately every 6,000 milies.  This program  found that  the
 test buses were able to travel far; beyond this distance without
 unacceptable deterioration of oil  quality.  The  type of filter
 used appeared to have no significant effect.  It appears that bus
 engine manufacturer recommendations  for oil change  intervals are
 highly conservative and may be safely increased  for fleets  that
 conduct routine oil quality mohitoring like OCTA.

      Oil filter changes not including the cost of oil are
 estimated  to cost $30 each for the pleated paper filter and $40
 each for the composite synthetic media filter.   Since the
 reusable filter is  not replaced at each oil change,  it  is
 necessary  to amortize its  $364'installed  cost over  an estimated
 10 year life.   Adding labor and expendable parts cost (e.g.   .
 gaskets) the estimated cost of cleaning the reusable filter is
 slightly lower at $27.50 per cleaning,  based upon 8  cleanings per
 year.  Fewer cleanings result in a higher cost per  cleaning due
 to constant amortization cost.   Basically, there is  no
 significant difference in  the comparative cost of using the three
 filters tested.   However,  the use  of  the  reusable reduces the
 disposal of 8  filters per  year per bus.   For a fleet of 450  buses
 (OCTA), this  is  100  drums  of oil filter waste per year.

      If the interval  between oil changes  were increased from
 6,000 to 18,000 miles,  the annual  cost  savings would be
 approximately  $350 per bus per year and annual oil disposal  would
be 170 gal  per bus per year less based  on 48,000 miles  driven per
year.  For  OCTA this  would be  a  savings of $157,000 per year and
decreased oil disposal  of  1390  drums per  year.

     As stated previously,  synthetic  filters did a better job of
 filtering out particles <25 microns in the oil.   The reduction of
these particle counts may  be helpful  in extending the engine's
life.  However, research is needed to quantify the relationship
between engine oil particle counts and engine life between
overhauls.   If reduced particle counts should have a significant
effect in increasing  engine life, the potential  economic benefits
are large.

                                       James S. Bridges
                             Risk Reduction Engineering Laboratory
                                 26 W. Martin Luther King Drive
                                    Cincinnati, Ohio 45268
       The Waste Reduction Evaluations At Federal Sites (WREAFS) Program is a cooperative research,
development and demonstration (RD&D) program between the US Environmental Protection Agency and
the Federal community at large. The three primary objectives of the WREAFS Program are to : 1)
conduct waste minimization assessments and case studies; 2) conduct pollution  prevention research
and demonstration projects jointly with other Federal activities; and 3) provide technology and
information transfer of pollution prevention results.  Since the initiation of the WREAFS Program in 1988
within the Risk Reduction Engineering Laboratory's Pollution Prevention Research Branch, the Federal
community has initiated constructive action and demonstrated awareness of the significance of pollution
prevention in the production and consumption of goods and services for the Federal government
nationwide and abroad. This abstract provides a summary of the current cooperative RD&D projects
within the Federal community under the aegis of the WREAFS Program.


       The waste minimization assessments are conducted  by an assessment team that is composed
of personnel from EPA, personnel  from the cooperating Federal facility, and others who can provide
technology and processing expertise. The assessments follow the procedures described in the EPA
report, Waste  Minimization Opportunity Assessment Manual.  (EPA/625/7-88/003) which is available from
the Center for Environmental Research Information (CERI), Publications Unit, 26 West M.  L. King Dr.,
Cincinnati, Ohio, 45268. This Manual provides a systematic procedure for identifying ways to reduce or
eliminate waste generation. The conduct of a waste minimization assessment results  in the waste
generating activity identifying solutions and RD&D needs. The active participation as part of the waste
minimization assessment team also provides on-site training for Federal personnel, encouraging
continued use of the EPA Manual at other waste generating activities within a Federal Department.  This
hands-on experience is one reason for targeting at least one joint waste minimization  assessment
between EPA and each of the fourteen Federal Departments.  Results from completed waste
minimization assessments are documented with a report and project summary for technology transfer to
both the public and private sectors.
       Completed waste minimization assessments available through CERI include:
Waste Minimization Opportunity Assessment:
Philadelphia Naval Shipyard
Waste Minimization Opportunity Assessment: Fort Riley,







 Waste Minimization Opportunity Assessment: US Coast
 Guard Support Center, Governors Island, New York

'Waste Minimization Opportunity Assessment: Naval
 Undersea Warfare Engineering Station, Keyport,

 Hospital Pollution Prevention Case Study

 Waste Minimization Opportunity Assessment: Optical
 Fabrication Laboratory, Fitzsimmons Army Medical
 Center, Denver, Colorado

| Waste Minimization Opportunity Assessment: Scott Air
 Force Base

 Waste Minimization Opportunity Assessment: US Coast
iGuard Base Ketchikan, Alaska and

 Waste Minimization Implementation Plan: US Coast
 Guard Base Ketchikan, Alaska are results of a joint
 project between EPA's Region 10 Federal Facilities
 Program and RREL
       Other planned and ongoing waste minimization assessments to be completed in FY 92 include
joint assessments with the Department of Interior's Bureau of Mines, the US Army's facility in Ft. Carson,
Colorado, the Department of Agriculture's Research Service in Beltsville, Maryland, the Department of
Treasury's Bureau of Engraving and Printing and the US Department of Energy's Sandia National
Laboratories.                               ;

       The Tidewater Interagency Pollution Prevention Program (TIPPP)  is a cooperative effort among
EPA, DOD, and NASA to take advantage of the (capabilities of well-defined communities  to develop a
pilot program, establishing an integrated multi-media pollution prevention plan that includes both short-
and long- term projects with results that will be transferable to other Federal and public  communities.
Through a number of WREAFS sponsored pollution prevention assessments at selected  operations at
each of the host facilities, pollution prevention recommendations will be considered for implementation
or further demonstration.  The host facilities are located at Ft. Eustis, Langley AFB, Langley NASA, and
Navy Base Norfolk.  WREAFS is also developing a series of Pollution Prevention Fact Sheets on
processes, products, and various activities prevalent at TIPPP installations to assist with  more generic
short-term issues. It is anticipated that TIPPP facility managers will  utilize the P2 information to reduce
the generation of wastes from selected processes and each alternative will be documented and
transferred throughout the Federal community.  At the end of FY 92 RREL support to TIPPP should
Include up to thirty waste minimization assessments and fifteen P2 Fact Sheets. Due to  the importance
and widespread transferability of the results from RREL support to the TIPPP, the majority of WREAFS
resources have been allocated for the TIPPP  projects.


       A number of RD&D needs have arisen from the conduct of waste minimization assessments
since there are not optimum solutions available for every waste generating problem.  When a solution is
not technically sound or does not exist, or solutions are not economically feasible, the stage is set for

RD&D. The WREAFS Program has concentrated on waste minimization assessments during the first
three years and with the successful completion of these assessments and case studies, it is felt the
WREAFS Program will target RD&D within the Federal community for the next several years. The
Pollution Prevention Research Branch has conducted RD&D activities within the Federal community over
the past three years such as: the evaluation of emulsion cleaners at US Air Force Plant No. 6; waste
reduction from chlorinated and petroleum-based degreasing operation with Auburn University for Tyndall
AFB; the evaluation of a wet to dry Navy spray paint booth; reclaiming fiber from newsprint with USDA;
and investigating and developing wood/plastic composites with USDA's Forests Product Laboratory.

        RD&D projects  planned and on-going for FY 92, in addition to what will  result from the TIPPP,
include support to the Air Force and Navy.  The WREAFS Program is planning technical support to the
Naval Civil Engineering  Laboratory (NCEL) for a joint project with a FY 92 start regarding industrial
wastewater treatment plants (IWTP).  This in-house study calls for a feasibility analysis to determine
future needs which consider pollution prevention solutions to current and future pollution generating
issues as well as emerging waste management technologies. The initial meeting for this technical
support project is for RREL to host a workshop on January 29, 30, and 31.

        Tinker AFB and RREL are working on a joint RD&D project designed to evaluate five major
chemical waste generators as the overhaul/repair processes associated with CFC's, electroplating,
component cleaning, painting/de-painting, and vapor degreasing.  The objective of this project is to
identify and assess alternative processes that will enable the Oklahoma City - Air Logistics Center to
minimize waste generation while meeting overall mission objectives.  By the end of FY 92, completed
activities will include baseline data gathering,  alternative identification and characterization,  alternative
assessment, and selection of alternatives.

    The objective of another Tinker AFB - RREL joint RD&D project is to minimize the amount of
hazardous chemicals used in plating by implementing electrochemical metallizing (EM). Using
computerized numerical control, serni-automatic, or fixed  station systems for EM plating of parts which
are currently bath plated, EM plating will reduce chemical usage thus reducing the amount of hazardous
wastes being generated in the  repair and overhaul  of gas turbine engines.  This project includes seeking
an acceptable substitute for chrome plating, providing a demonstration line for semi-automatic EM nickel
plating, performing cost comparisons between tank plating and EM, and assessing the quality of the
parts being plated.  The impact of EM plating could be substantial for reducing  chemical requirements.


        Technology transfer continues to result from project reports and project summaries of
completed  WREAFS projects.  As  noted earlier, the waste minimization assessments provide an
opportunity for training and change in culture to thinking  pollution prevention rather than end-of-pipe
control.  It  is important for the  Federal community to be leaders in pollution prevention and to provide
examples to others in the private and public sectors. A number of pollution prevention
workshops/conferences or parts of environmental  conferences which include pollution prevention have
participants from the Federal community. This technology transfer allows for an integrated approach to
the problems of waste  generation  in the United States.  Stepping down from the aloofness of sovereign
immunity, the Federal government and business are working together toward pollution prevention
solutions.  The WREAFS Program is  providing the forum and technical foundation for the
encouragement of pollution prevention research in the Federal community. Using lessons  learned RD&D
for pollution prevention answers throughout the Federal community, joining RD&D resources to find
solutions to common waste generating  problems, and working together to bring about the cultural
change in thinking pollution prevention are the goals of the WREAFS technology transfer efforts.

        Federal scientists and engineers are invited to share RREL facilities and interact with RREL
scientists and engineers in promoting a research cooperative for Federal facilities.  It is the vision of
RREL that scientists and engineers from other Federal Agencies would be assigned to RREL for a
specified period to work on a pollution prevention research project of that Agency or assist RREL with
pollution prevention research projects that will be applicable to all Federal facilities. The contacts, joint
RD&D, and training will benefit both EPA and the other Agencies. Participation in this "cooperative" is
strictly voluntary.                            ;


       The WREAFS Program takes on many facets in  its endeavor to support the Federal community
with pollution prevention research. There has been a number of RD&D products that have been
completed and a number of on-going efforts, but perhaps the most important impact will come from any
resulting cultural change brought about by conducting a waste minimization assessment or reading a
RD&D report. The Federal facilities "cooperative" is one idea that should be a big benefit for the Federal
community and pollution prevention once support is provided. It is necessary for all of the fourteen
Departments to take an active role in pollution prevention and be an example to the rest of the world.

                             MEASURING POLLUTION PREVENTION

                                       David G. Stephan
                                       James S. Bridges
                              Risk Reduction Engineering Laboratory
                                     Cincinnati, Ohio 45268
       To assess progress in pollution prevention, estimates or measurements of the amounts of
pollution actually prevented have to be made. Such estimates or measurements tell us how far we have
come and, possibly, how much farther there is to go in utilizing pollution prevention as a tool for
improving environmental quality.  They can, theoretically, be used to assess progress on a scale ranging
from the individual facility or even the individual process or activity generating wastes to a scale as large
as a geographical area such as a county, a state or even the United States as a whole.

INDUSTRIAL SOURCES                                  .

       A major step in being able to assess pollution prevention progress by industry was the provision
in the recent Pollution Prevention Act requiring the addition of a "toxic chemical source reduction and
recycling report" to the annual Toxics Reduction Inventory (TRI). This report, beginning in 1992, will
attempt to quantify the pollution prevention progress actually occurring with respect to certain toxic
chemicals used by industry. Progress will be assessed through the tabulation of such information as the
quantities of the chemicals entering wastes or otherwise released to the environment, the amounts
recycled at the facility or elsewhere, etc.

       Roughly a year ago, an early version of this source reduction and recycling report was evaluated
"in the field" by Battelle Columbus Operations under a Pollution Prevention Research Branch support
contract (1). The draft report form was distributed to nine companies which had volunteered their
services to "test" it. The companies were provided with the form and its instructions and asked to
complete the form and then to meet with Battelle evaluators. By interviewing the companies, the
evaluators tried to ascertain 1) the clarity/understandability of the form and its instructions, 2) the ease or
difficulty of responding to the questions, 3) the reliability and meaningfulness of the data reported, 4) any
concerns over confidentiality of the data requested and 5) the overall "burden" of responding and to
obtain suggestions for improvement:

       In addition, the draft report form was sent to several industrial trade associations and public
interest environmental groups for their reactions.

       As might be expected, the field test participants and the trade associations had very similar
comments but the environmental groups commented from a different perspective. All commenters
agreed that the purpose of the forms should be to collect the data needed to describe pollution
prevention progress, to encourage pollution prevention, to express progress to the public and to identify
opportunities for further pollution prevention. Commenters also agreed that the definition of terms
needed to be clarified, especially terms such as open-loop and closed-loop recycling.

       On the other hand, industry and public interest groups differed on how closely the TRI and RCRA
reporting processes should be connected.  Environmental groups wanted to see a close tie between
these reports while industry reviewers felt that even the qualitative connection proposed  in the form would
be difficult to implement. There was also considerable variance in views as to the level of detail available
or appropriate for reporting.  Industry commenters expressed concern that the report would not always

 capture a true picture of their pollution prevention activities.  They also felt that requirements to report
 expected progress might be converted into auditable goals. A major issue involved the "starting point" to
 be used as a baseline for assessing progress. It was felt that firms that had already aggressively
 implemented pollution prevention would suffer in comparison with firms that had done nothing to date
 and still had "the low-hanging fruit to pick." Another item that elicited much comment related to the so-
 called Production Ratio or Activity Index aimed at normalizing data from year to year based on the level of
 production or activity taking place at a facility.  Itjwas urged that flexibility be allowed in choosing the most
 appropriate Index for each chemical being reported.

        With the passage of the Pollution Prevention Act, a mandated set of source reduction and
 recycling questions will be added to the TRI beginning in 1992. These questions and the instructions
 related to them have benefitted from the results pf this field test and from considerable other input from a
 wide variety of industrial, public interest and other groups over the last year or so.


        Battelle was also asked to develop a methodology for  measuring pollution prevention progress in
 the agricultural sector (2).  Focus was placed on: three types of agricultural pollution: fertilizers, pesticides
 and concentrated animal wastes. With regard to fertilizers and pesticides, it was felt that application rates
 could serve as simple surrogates for "wastes generated" and that, generally speaking, reductions in
 amounts applied from one year to another would approximate pollution prevented. It was recognized,
 however, that many factors other than the introduction of pollution prevention techniques affect amounts
 applied. For fertilizers, amounts are impacted, for example, by type of crop, crop rotations, weather and
 market factors. For pesticides, one must also consider, for example, cyclical infestations and pesticide
 fo'rmulations available. The pesticide situation is,  of course, considerably more complicated because of
 the many, many different types and potencies of [pesticides whereas fertilizer pollution is essentially limited
 to the three major nutrients, potassium, phosphqrus and nitrogen.  Because of the normal year-to-year
 variations, it was felt that data on application rates would have  value only to detect trends over extended
 periods such as 5 or 10 years.                 '
        With respect to animal  wastes, the possibilities for accomplishing true "source reduction" are
 quite limited. The primary methodology examined from the standpoint of how to assess pollution
 prevention progress was the use of growth hormones to increase the amount of product (meat, milk,
 eggs) per unit of manure excreted.

        In all cases, Battelle's proposal was to survey a representative sample of farmers to determine the
 rates at which various pollution prevention techniques were being applied.  From this information along
 with data on how much pollution is prevented by: each technique, an estimate of overall pollution
 prevented could be made.

        Battelle's findings in the agricultural area, while not providing any specific methodology ready for
field testing, should help in providing a basis for 1) refining and expanding the list of pollution prevention
 practices applicable to agricultural activities, 2)  measuring reduced fertilizer or pesticide use rates under
 different circumstances and 3) estimating the adoption rate for various agricultural pollution prevention


       A third task assigned to Battelle (3) was to develop a methodology for measuring pollution prevention
progress occurring as a result of actions or decisions taken during the design stage of a product.  This is
important since the TRI will collect information only on pollution prevented during the manufacturing
stage.  Yet, through astute product design decisions, much pollution can and will be prevented during
other stages of the product's life than the manufacturing stage; most importantly, perhaps, pollution
prevention as a result of product design will primarily occur during product use and at the time the
product's useful life ends and the product, itself, becomes a waste.

       Since a designer is able to influence the raw materials used, the production process employed,
the way in which the product is used, its life, its "repairability," its recyclability and even the mode of its
eventual disposal, product design decisions which beneficially influence any of the above potential
environmental impacts should be acknowledged. This effort is an attempt to define how this might be


1.     Otfenbuttel, R. F. and Smith, L. A. Source Reduction Measurement Methodology for Consumer
       Products. Unpublished final report (Task 1, WA 0-12, Contract No. 68-CO-0003, Battelle
       Columbus Operations), Risk Reduction Engineering Laboratory, U.S. Environmental Protection
       Agency, Cincinnati, Ohio, 1991.

2.     Concepts for Measuring Pollution Prevention Progress in United States Agriculture.  Unpublished
       final report (Task 2, WA 0-12, Contract No. 68-CO-0003, Battelle Columbus Operations), Risk
       Reduction Engineering Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio, 1991.

3.     Source Reduction Measurement Methodology for Consumer Products. Unpublished final report
       (Task 3, WA 0-12, Contract No. 68-CO-0003, Battelle Columbus Operations), Risk Reduction
       Engineering Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio, 1991.

                         FOR THE PRINTED blRCUIT BOARD INDUSTRY
                                       Teresa M. Harten
                              U.S. Environmental Protection Agency
                                      26 W M L King Drive
                                    Cincinnati, Ohio 45268
                                        (513) 569-7565
       The Minnesota/EPA Waste Reduction Innovative Technology Evaluation (WRITE) Program is
 one of seven programs nationwide in which EPA and cooperating states or local governments
 evaluate and demonstrate the engineering and ^conomic feasibility of selected waste reducing
 technologies in a manufacturing or fully operational setting. The program in Minnesota, which began
 in mid 1989, targets the metal finishing industry; specifically rinsing operations within metal finishing
 operations, as the focus of the evaluations. The 5 technology evaluation projects planned for the full
 life of the Minnesota/EPA Program and subsequent technology transfer activities are intended to
 speed the early introduction of cleaner, pollution preventing technologies in the metal finishing
 Industry.  This extended abstract presents final results from the first project and preliminary results
 from the second project conducted under the Program.


 PROCEDURE                              :

       Micom, Incorporated is a medium-sized job shop circuit board manufacturer employing
 approximately 240 people at its plant  in New Brighton, Minnesota.  Under a number of  military and
 commercial contracts the company produces an average of 1000-1200 square feet of double sided
 multilayered panels per day.  In 1989, annual revenue was $17 million.

      The evaluation took place at the sensitize, line where a number of process baths  including
 etchant ("micro-etch"), activator, accelerator, electroless copper and rinse tanks, first etch and then
 chemically deposit copper onto the insides of the circuit board holes.  Drag out from two of the line's
 process baths, the micro-etch and the electroless copper baths, was a significant source of waste
 copper discharged in the rinse water waste stream  leaving the line. This rinse water had to be treated
 by an on-site ion exchange unit for copper removal before it could be  discharged to public sewer.

      Baseline samples and measurements were taken over a two week period to determine the
 initial drag out rate in milliliters per square foot of board plated. Enough sample sets were taken to
 calculate 12 values for the drag out which were then averaged.

      For the first modification, the hoist system was  slowed from the baseline withdrawal rate of 100
ft/min for the micro-etch line and 94 ft/min for the electroless copper line to 11 ft/min for the micro-
etch line and 12 ft/min for the electroless copper line.  Samples were taken and measurements made
to determine the drag out after modification 1 was put in place.  Again, the number of sample sets
enabled 12 drag out values to  be calculated.

      For the second modification, the withdrawal rate was set at an intermediate rate between
baseline and modification 1, and the drain time over the bath was increased. Withdrawal rates were

40 ft/min for both micro-etch and electroless baths, and drain time was increased from a baseline of
3.4 seconds to 12.1  seconds for the micro-etch line and for the electroless line from 5.2 seconds to
11.9  seconds.  Samples were taken to provide 12 calculated values for drag out.


      Both modifications reduced drag out significantly. Baseline drag out from the micro-etch bath,
12.1  ml/tf , was reduced to 6.7 ml/fl2 or 45% by modification 1, and the electroless copper bath drag
out was reduced from 6.0 ml/ft2 at baseline to 3.0 ml/ft2 after modification 1, for a reduction of 50%.
After modification 2, the micro-etch drag out was 7.1  ml/fl2, a reduction of 41% from baseline, and for
the electroless bath, drag out was 2.9 ml/fl2, a reduction of 52%.

      By reducing drag out in these amounts, 203 and 189 grams of copper per day were prevented
from being discharged as waste in the rinse water waste stream, for modifications 1 and 2
respectively.  Because copper concentration in rinse water was reduced, the potential for conserving
rinse water flows was also shown, although this was not directly tested. Rinse water flows could be
turned down proportionate to the reduction in drag out and still maintain the same rinsing efficiencies.

      The economic savings due to these reductions were calculated by taking into consideration
avoided cost of treatment of the rinse water and avoided charges for water and sewer service.  If
implemented, the first modification would save the company $3350 - $2640 savings in treatment costs
and  $710 in avoided water and sewer costs. The same figures for implementing the second
modification would be $3120 - $2460 in treatment costs  and $660 in avoided water and sewer
charges. Since no capital costs were incurred in making the changes, payback would be immediate.

       In the first project, the waste reducing capabilities of two simple rinsing modifications were
demonstrated at a Minneapolis area printed circuit board manufacturer. The no cost, low technology
changes made were 1) slowing the withdrawal rate of racks containing the printed circuit boards as
they were pulled from an etchant process tank and an electroless copper process tank and
2) combining an intermediate withdrawal rate with a longer drain time over the process tanks. Both
modifications significantly reduced drag out of concentrated copper containing bath solutions into the
rinse water systems.



       The second project took place at a flexible circuits manufacturer which employed
approximately 1800 and had annual sales of $92 million in 1989.  Two technologies were tested  for
their ability to reduce waste: 1) soft absorbent polyvinyl alcohol (PVA) rollers replacing  hard rubber
squeegees to reduce drag out in a horizontal cleaning operation and 2) adding a conductivity
activated flow controller to reduce rinse water in a tin lead plating line.  The company had  identified
the cleaning operation and the tin lead line as its largest waste generators and the areas it believed
offered the largest potential for waste reduction. Waste streams from both lines were treated on site
by lime precipitation, sludge pressing and drying and off site sludge disposal as hazardous waste.
Treated waste water was discharged to sewer.

       Initial testing was conducted in May, 1991.  While testing was completed for the conductivity
flow controller evaluation at that time, the company continues to monitor the cleaning line to
determine sponge roller effects on cleaning ba^h life.

       The PVA "sponge" type rollers were tested for drag out reduction at an acid cleaning tank
which was part of a larger cleaning operation that removed oil, grease, and chromate conversion
coating from flexible copper sheets in preparation for the application of photoresist.  In testing the
sponge rollers, baseline samples taken over a two hour period included enough sample sets to
provide 10 drag  out values.  During baseline testing the line was operated  using the  hard rubber
squeegees that come as standard equipment with the cleaning units.  Next, for the evaluation phase,
the squeegees were removed and replaced with PVA sponge rollers. Sampling again was performed
over a two hour period to provide 10 sets of samples for drag out calculation.  Samples were
analyzed for copper concentration as an indicator of drag out. In both baseline and evaluation
sampling, flexible circuit throughput was also tracked to enable a drag out per square foot calculation.

       In the second evaluation at the flexible circuits manufacturer, a conductivity sensor and flow
controller were installed at a tin lead plating line to reduce rinse water flow from the triple
countercurrent rinse system.  Before  installation of the flow controller, baseline flow was measured
using a totalizing flow meter at the influent line to the rinse system.  Flows  were recorded every 8
hours for a one week period; conductivity was &lso recorded  over this period to help establish a set
point for the conductivity flow controller.      :

       After baseline sampling, a conductivity sfensor was installed in the final rinse tank and
connected to a controller. The controller was set to activate a valve at the rinse water influent line
when the sensor reached the set point of 30 mS.  When conductivity reached this level in rinse water,the
valve opened and allowed rinse water to flow to the rinse tanks.  The 30mS level was chosen as the
approximate median level of the conductivity readings found during baseline testing. The company
believed this to be a conservative estimate for the  contamination that could be tolerated by the
system and still maintain effective rinsing. Again during evaluation, flow was recorded every 8 hours
over a one week operating period. During baseline and evaluation monitoring, throughput of flexible
boards was also tracked.


      Testing of the sponge rollers for drag out reduction at the cleaning line showed the sponge
rollers to be successful in reducing drag out. Baseline testing of the hard rubber rollers determined
that drag out was originally occurring at the rate of 27.6 ml/fr. After installation of the sponge rollers
drag out was reduced to 9.8 ml/ft2, a 64% reduction from baseline.  Rinse water could be
proportionately reduced without compromising rinsing efficiency.
      While drag out, as measured by copper concentration  in the bath and rinse tank following it,
was reduced, the increased rate of copper build-up in the cleaning bath tank suggested that the tank
would have to be replaced more frequently since the company used bath copper concentration as a
measure of bath  contamination  and as an indicator for bath replacement. At present, the company is
conducting a longer term study to determine the impact of the rollers on bath life.  This information is
critical to drawing a comparison between waste  generated using hard rubber versus  sponge
squeegees. The economic evaluation will also have to await this information before the two  can be

      For the other evaluation conducted at the flexible circuits manufacturer, baseline testing of the
rinse flows to the tin lead line showed that 1.41 gallons/fl? of rinse water were used in the triple
countercurrent rinse system before installation of the flow controller.  After the conductivity sensor and
flow controller were installed rinse water flow was reduced to 0.64 gallons/fl2, a reduction of 55%.

      The economic analysis showed that this reduction in rinse water would save $132/yr in avoided
water and sewer utility charges and $877/yr in avoided rinse water treatment costs. The total savings
per year of $877 divided into the $500 installed cost of the flow controller/sensor combined with its
$50/yr operating cost, results in a payback of 7.5 months.

CONCLUSION                                         ,

      The evaluation  of the flow controller at the flexible circuits manufacturer clearly showed that
waste could be reduced and savings achieved when used on a tin lead line rinse system. The results
are not yet available for the sponge rollers installed at a cleaning line; although it reduced drag out
significantly, the increased build up of copper in the cleaning bath required more frequent bath
replacement. The company continues to monitor the change in bath life to provide a more complete
picture of waste generated and associated costs before and after the change to sponge rollers.

                             EVALUATION OF EMULSION CLEANERS
                                AT AIR FORCE PLANT NUMBER 6

                                       Johnny Springer, Jr.
                                 Waste Minimization, Destruction
                                 and Disposal Research Division
                              Risk Reduction Engineering Laboratory
                                      Cincinnati, Ohio 45268
                                         (513)  569-7542

                                           Gary Baker
                           Science Applications International Corporation
                                  635 West 7th Street, Suite 403
                                      Cincinnati, Ohio 45203
   The eva'uation of emulsion cleaners at Air Force Plant 6 project is an offshoot of the Waste
Reduction Evaluation at Federal Sites (WREAFS)S Program conducted within the Pollution Prevention
Research Branch. The WREAFS program consists of a series of demonstration and evaluation projects
for waste reduction conducted cooperatively by the U.S. Environmental Protection Agency (EPA) and
various divisions of other federal agencies. The purpose of this project is to provide assistance to Air
Force Plant 6 personnel by documenting the relevant work by other aircraft fabrication facilities to
support comparison of cleaner qualification performance with trichloroethylene for the vapor degreaser
operations at Air Force Plant 6.


   Air Force Plant No. 6, located in Marietta, Georgia, is  operated for the Air Force by Lockheed
Aeronautical Systems Company. The facility is part of the Aeronautical Systems Division (ASD), whose
headquarters is located at Wright-Patterson Air Force Base near Dayton,  Ohio.  There are six vapor
degreaser units that utilize trichloroethylene  (TCE) to prepare steel and aluminum parts for a variety of
subsequent manufacturing steps in the production of C-130 aircraft.

   Although the usage of trichloroethylene has decreased from 1.2 million pounds in 1988 to about
650,000 pounds in 1990, the decrease has been largely due to a diminishing workload at the plant.
Lockheed Environmental Department and Materials and Processes Department staffs are interested in
substitution of the current solvent with appropriate cleaners due to concerns about worker safety and
health  in addition to the environmental impacts of the current solvent.  The eventual goal of the facility is
to substitute water-soluble emulsion cleaners to pbviate use of 650,000 pounds of TCE.

   During the initial phases of this project, it was decided to investigate  research conducted by other
aircraft manufacturing entities prior to conducting full scale testing of a targeted list of cleaners. As a
result of canvassing various businesses within the aircraft manufacturing  industry, it was determined that
a substantial amount of research was currently being conducted. The  facilities conducting research
were cooperative in sharing information and as a result, it was  decided to document research currently
befng conducted and submit a report to Lockheed to use as a starting point for determining where to
begin their research.

    The information for this report was developed by documenting research performed by Boeing
Aircraft, Air Force Engineering Service Center (AFESC), General Dynamics, Lockheed  Missile and Space
Company (LMSC), Martin Marietta and Northrop. This research information was particularly useful since
Lockheed qualification criteria are based on Air Force (military specifications), Lockheed and Boeing
tests.  Lockheed currently conducts significant subcontractor work for Boeing.  Also, data and
information for the report was accumulated from emulsion cleaner manufacturers/suppliers and an
international workshop on solvent substitution.

Boeing Aircraft                                                     -

    Boeing Aircraft Corporation has been investigating the replacement of solvent and  vapor degreasing
processes  for the past three years. Specifically, Boeing has ongoing research efforts with requirements
similar to Air Force Plant 6 at three locations.  Boeing is evaluating cleaners at its Wichita, Puget  Sound,
and Kent Space Center facilities in actual shop trials. Shop trials are pilot programs designed to
evaluate the performance of a given solvent during  actual production. The  Puget Sound plant
manufactures commercial aircraft; the other two facilities are strictly involved in  military aircraft
production. The Boeing site that offers data most relevant to the Plant 6 program is located at  the Kent
Space Center.

Air Force Engineering Service Center (AFESC)

    AFESC has been active in solvent substitution over the past several years. One of their projects is
substitution of cleaners with  biodegradable solvents. This project was conducted in three phases.
During Phase I, nearly 200 companies were contacted and 185 different  solvents were  obtained for
testing. These tests looked at biodegradability, ability to dissolve soils, cleaning efficiency, and
corrosiveness (if able to pass the other three).  From these tests, the most promising were identified for
further testing in Phase II.

    During  Phase II testing, solvents were subjected to extensive performance testing at the field test
facility at Tinker AFB, Oklahoma. AFESC evaluated enhancement methods  (ultrasonic  and mixer
agitation at various temperatures)  on  a revised list of solvents which originated in Phase I. Phase III
tests evaluated solvents during implementation.  The cleaners evaluated  in Phase III were the same
cleaners evaluated in Phase  II.

    The U.S. DoE is sponsoring continuation work.  They are working on a related project which will
study solvents and their ability to clean approximately 20 different "soils" (this term is Used to refer to any
processing contaminant that must be removed from a part surface). These  tests will focus on
performance and corrosion rather than biodegradability.  Once the most promising  cleaners are
identified, additional tests will be performed for recyclability and VOC emissions.  It  is hoped that the
information from the earlier report can complement  this report in order to form a comprehensive
database on solvents.

General Dynamics

    Of the research efforts investigated for this study, General Dynamics  is the most comprehensive
program. The program is being conducted at the Fort Worth  Division and is currently in shop trial. The
program initially evaluated 40 cleaners and screened to five cleaners.  One of the five cleaners was
eliminated due to corrosion test concerns. The four remaining candidate cleaners were optimized with
General Dynamics' input.  One product is compatible with the solvent regeneration process in use at
General Dynamics and is  currently being used in the shop trial program.

Lockheed Missile and Space Company (LMSC)j

   LMSC staff have been involved in evaluating non-hazardous cleaners since August 1989.  Their goal
has been to find suitable replacements for l.l.t-trichloroethane (TCA) used in vapor degreasers.  The
LMSC program seeks to replace all TCA used in a variety of processes throughout their facility.
Cleaning performance, compared with TCA, as well as the etching and corrosion effects on magnesium
and aluminum surfaces were evaluated.       |

Martin Marietta

   Martin Marietta staff in Denver have completed an aggressive solvent substitution program that
sought to replace TCA. Numerous tests were performed on cleaners to clean aluminum soiled with fish
oil, mineral oil, glycerine, machining oil, layout Clye, and aluminum mill stamps.


   Northrop  used a different strategy for evaluating cleaners: they simply told the manufacturers to send
them their best formula with instructions for use and the product would either pass or fail.  No
experimentation or cleaning optimization was attempted.


   The final report has been compiled for this project.  The report contains information on the
evaluation of various substitute cleaners on the conformance of the emulsion cleaners to be
Implemented at Air Force Plant No. 6 with specific qualification test criteria. The document contains the
specifications for qualification tests in 17 areas. The 17 test areas are:
               Corrosion between
               faying surfaces
               Effect on Cd plated
               Effect on Adhesion
               Water break-free
Sandwich corrosion
Intergranular Attack
Corrosion Resistance

Paint Adhesion
 It also contains a list of ten cleaners that were targeted for evaluation.  Table 1 presents a summary of
 the cleaners evaluated by the various organizations in the determination of a substitute for halogenated
 solvents.  This table provides information on what cleaner(s) were tested. It also provides the reason
 why a cleaner was disqualified from further testing and which cleaners are currently being investigated in
 pilot tests. Although in most cases the companies conducting the research  sought to replace TCA, the
 industrial  processes are analogous to those conducted at Air Force Plant 6.


* Grace Duraclean 282
* Turco 6778
* Turco 4215 NCLT
• Turco 3878
* Blue Gold
* Brulin 815 GD
* Hurri-Klean
* Quaker 624 GD
* Polychem 2000
* Novamex
* Rochester-Midland
(Biogenic SE373
Bioact EC7
Simple Green
Coors Bio T
Oakite Inproclean 2500
3D Supreme
RB Degreaser

























* Lockheed Air Force Plant 6 target cleaners

       a - Evaluated
       b - Selected for implementation or further evaluation
       c - Implemented
       d - To be evaluated

Eliminated due to:

       (1) Phosphates
       (2) Flammability concerns
       (3) Not easily recyclable
       (4) Unacceptable etching of magnesium substrate
The document concludes with a chart that compares the performance criteria of the various companies
to the criteria required by Lockheed.


        EPA is continuing to work in cooperation with Lockheed Aeronautical Systems Company-
Georgia and Air Force Aeronautical Systems Division to investigate the potential for implementing
emulsion cleaners as a replacement for trichloroethylene (TCE). The substitution of emulsion cleaners
for TCE Is currently being implemented at Air Force Plant No. 6.  Lockheed has selected cleaner Brulin
815 GD from this report for pilot testing. As a follow-up to successful pilot testing, further testing is
planned in 800 gallon and 3400 gallon tanks respectively.  Lockheed  is providing funding for the pilot

        It Is anticipated that this substitution will function as a degreasing solvent as well as an alkaline
cleaner.  It will reduce tankage and eliminate or reduce substantially the use of chlorinated solvents at
Air Force Plant 6. EPA will  be cooperating with Lockheed and Air Force personnel to document the
successes, problems and costs associated with the change.  The results can then be transferred to
similar facilities in the Department of Defense or the Department of Energy, and can serve to expedite
the use of emulsion cleaners at other facilities.


                                        Paul M. Randall
                              U.S. Environmental Protection Agency
                              Pollution Prevention Research Branch
                                    Cincinnati, Ohio  45268


                                       Arun R. Gavaskar
                                    Columbus,  Ohio  43201
       Government regulations and high waste disposal cost of spent automotive coolant have driven
the vehicle maintenance industry to explore on-site recycling.  The USEPA in cooperation with the New
Jersey Department of Environmental Protection (NJDEP) and the New Jersey Department of
Transportation (NJDOT) evaluated two commercially available technologies that have potential for
reducing the volume of spent automotive coolant.  The objective of this study was to evaluate the
quality of the recycled coolant, the pollution prevention potential, and the economic feasibility of the
        Engine coolants are intended to provide protection against boiling, freezing, and corrosion.
Through use, the coolants lose some measure of these functions because of accumulation of
contaminants and the depletion of additives such as corrosion inhibitors and anti-foam agents.  The
recycling process  attempts to restore the functions of the coolants to standards specified in ASTM D
3306-89 and SAE J1034 (for automotive coolants) and ASTM D 4985 and SAE J1941 (for heavy-duty

        The first technology involved chemical filtration to recycle spent coolant and was manufactured
by FPPF Chemical Co. This technology consisted of two separate units; a fleet size unit that operates
on up to 100 gal of stored spent coolant and a smaller portable unit that operates on a per vehicle
basis and does not require prior collection and storage. The process for both units is similar. The
stored  spent coolant is drawn into a  100 gal plastic holding tank from which it is circulated through
filters,  aerated to form oxides of dissolved metals, and refiltered. The coolant pH is measured after
initial filtration and compared to a chart that shows how much additive is needed to raise the pH to 9.5.
The high pH helps to reduce the corrosivrty of the coolant.  In addition to raising the pH, the hydroxide
portion of the additive precipitates soluble  metals which are continuously filtered out.  The additive also
contains a blend of inhibitors, polymers, and surfactants to improve coolant quality.  Following pH
adjustment, the freezing point of the  coolant is checked with a  hand-held refractometer. A chart tells
the operator how much virgin coolant must be added to achieve a freezing point of -34 F or lower. The
portable unit had an ion exchange column to further reduce metals.

        Primary batches of spent coolant (as received) were run through the fleet-size unit and portable
unit. The primary batches represented stored spent coolant from the automotive and heavy-duty
vehicles operated by NJDOT.  Three "spiked" (altered spent coolant) batches were also run. The
purpose of these  salts- and acid- spiked batches was to create exaggerated conditions to test the limits
of the recycling process.  A blank, consisting of virgin coolant and tap water, was run through the fleet-
size unit.  Samples of the spent, virgin, and recycled coolant were collected for analysis.

        The second technology evaluated was one of distillation to recover automotive and heavy duty
engine coolant. This coolant recycling unit was: manufactured by Finish Thompson, Inc (FTI). The unit
operates on up to 15 gallons of spent coolant per batch.  Spent coolant is poured into the distillation
still along with an additive to control boiling. The unit is switched on and allowed to operate until water
and ethylene glycol are distilled off into two separate clean drums outside the unit. This may take
about 12 to 15 hours for a full 15-gallon  load of spent coolant depending upon the amount of water
present. Water distills out first at atmospheric pressure into the processed water drum. As the
temperature rises, the vacuum pump switches on automatically and starts drawing out the glycol.  The
vapors are condensed by using tap water as the heat exchanger fluid or by using an optional chiller.
The condensate enters the primer tank, where it mixes with the  primer (ethylene glycol) and overflows
into the processed glycol drum. The processed [glycol and processed water can then be mixed in equal
proportions. Three gallons of distillation residue collects at the bottom of the still and is emptied out,
typically after five batches. Primary and spiked batches of spent coolant, similar to those run on the
filtration units, were also tested on this distillation unit.
        In this study, results of the analyses were compared against ASTM and/or SAE standards. After
recycling with the filtration unit, the boiling and freezing points of the coolant were brought as close to
standard as possible through use of the hand-held refractometer and alteration of the glycol-to-water
ratio. None of the recycled samples from the primary batches met the corrosion standards as
measured by the ASTM D 1384 and D 4340 tests.  The spiked recycled samples, however, met the
corrosion standards for the ASTM D 1384 test.( This variation may be because the amount of corrosion
Inhibitor added is based on the pH of the spent coolant.  Since the acid-spiked samples had lower pHs,
adding more corrosion inhibitor to the coolant resulted in better corrosion resistance.
                                           j                                           "
        The spent and recycled coolants from the filtration units were characterized chemically and
levels of contaminants, such as metals, chlorides, oil and grease, etc., were measured to determine if
these constituents affected performance.  After recycling, although levels of chlorides and sulfates were
not noticeably reduced in the coolant, the level of metals was considerably reduced.  This retention of
chlorides and sulfates in the recycled coolant may contribute to corrosion.

        After recycling with the distillation unit, freezing point was measured by a hand-held
refractometer and the ratio of processed water |o processed glycol was adjusted to meet freezing point
specifications. The freezing and boiling points were  in agreement with the recommended standard.
Both pH and corrosivity of the recycled coolant were also within specified limits. Corrosivity was
measured in terms of the weight loss of metal test specimens exposed to the coolant for two weeks.
The recycling process was able to restore the spent coolant to within specifications as compared to the
ASTM D 3306 standard.  The aluminum corrosion test (ASTM D 4340) was also run. This test
evaluates the effectiveness of recycled coolant to inhibit corrosion of cast aluminum alloys under heat
transfer conditions. This test is important because of the growing usage of aluminum instead of cast
fron In automotive engines. The batches were recycled to within the acceptable standard for this test.

The spent and recycled coolants were characterized chemically and contaminant levels were also
measured to determine if these constituents affected performance. The levels of calcium, magnesium,
iron, and zinc were reduced considerably in the recycled coolant.  Changes in levels of lead and
aluminum were hard to estimate due to low analytical recoveries and low starting levels of these metals
in the spent coolant.

        For both filtration and distillation, the pollution prevention potential was measured in terms of
the volume and hazard reduction. Volume reduction addresses gross wastestreams (i.e. spent
coolant, filters).  Hazard reduction involves individual pollutants( i.e. ethylene glycol, heavy metals )
contained in the wastestreams. The estimate of the amount of coolant that NJDOT disposes of
annually was based on the amount of new coolant that NJDOT uses annually decreased by 10% to
account for the environmental loss of coolant through leaks in the  vehicles cooling  systems.  Because
the coolant is recycled rather than disposed of, the volume reduction was calculated to be 8,812 gals.
The volume of sidestreams generated for disposal during recycling for filtration (e.g. filters) and
distillation {  e.g. residue ) were approximately equal.

        For filtration, the economic evaluation took into account the capital and operating costs of the
recycling equipment as well as the savings provided by decreasing the amount of raw materials (virgin
coolant, water) and reducing disposal costs.  Because of the relatively high price of virgin coolant and
the high volume of virgin coolant purchased by NJDOT, the recycling process was  found to have a
payback period of less than one year. This is assuming that the filtration unit is able to produce coolant
that meets quality standards.

        For distillation, the economic evaluation also took into account the capital and operating costs
of the recycling equipment as well as the savings provided by decreasing the needed amount of raw
materials (virgin coolant and water) and by reducing disposal costs.  The purchase price of the
recycling unit at the time of this evaluation was $ 5,115. Due to the  relatively high  price of virgin
coolant and high volume of virgin coolant purchased by NJDOT, the  payback period was much less
than one year. The payback varies  depending  on the amount of spent coolant generated annually by
the user.  For example, if a generator purchases 100 gals of coolant annually, the recycling unit may
not be economical.  A slightly larger generator,  with 500 gal/yr of purchased coolant, would have a
payback period of approximately seven(7) years.  The payback improves as the amount of coolant
purchased becomes larger.
        Although recycling by filtration has great waste reduction and economic potential, the filtration
unit evaluated in this study would require additional improvements to ensure an acceptable quality of
the recycled product.  Some possible areas of improvement are adjusting the method of determining
the amount of additive used and implementing a means of anion (chlorides and sulfates, etc.) removal
such as ion exchange.

        The distillation evaluation also shows good waste reduction and economic potential. The
NJDOT facility could potentially reduce waste from over 8000 gals to approximately 400 gal/yr.  The
recycled product in the distillation evaluation also fared very well in the selected ASTM performance
tests and the chemical characterization analyses.  Boiling point, freezing point, pH, and corrosion
resistance function of the coolant were restored to specifications. Metals, salts, and organic
contaminants were also removed.

        Several automotive and heavy-duty engine manufacturers are also beginning to evaluate

recycling. Such studies involve relatively expensive testing which may be costly for small repair shops
to conduct on their own. Some repair shops have already undertaken recycling based on information
provided by vendors to address the increasing cost of disposal. But in general, initial reaction to
recycling coolants in the automotive industry has been cautious, given the demanding nature of the

       This study was funded by the U.S. Environmental Protection Agency under Contract No. 68-
CO-0003 to Battelle.  It has been reviewed in accordance with the EPA peer and administrative review
policies and approved for presentation and publication.  Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.

             Stephen Vesper . Lawrence Murdoch
                 Mark Kemper, David Kreuzmann',
Rebecca Brand1, Phillip Cluxton
            Frank Sheehy
                          K. Pete Paris'
              Wendy Davis-Hooven,
 Department of Civil and Environmental Engineering,
              Center Hill Laboratory,
              Cincinnati, Ohio 45224,
   US EPA, Risk Reduction Engineering Laboratory
Municipal Solid Waste Research Management Branch
            Soils & Research Section
              Center Hill Laboratory,
              Cincinnati, Ohio 45224

       Bioremediation was determined to be a viable method of degrading the hydrocarbon
contaminants at a fuel distribution and storage facility in Dayton, Ohio. Laboratory tests done by the on-
site contractor indicated that percolating water containing oxygen and nutrients through the soil would
result in biodegradation of the contaminants. The site is underlain by silty clay till of relatively low
hydraulic conductivity, so conventional methods of delivery were expected to result in either slow rates of
percolation, and thus slow rates of remediation, or excessive drilling costs. Therefore, the site was
selected as a candidate for hydraulic fracturing, a technique of creating high permeability channel ways
in tight soils.


       The site was divided into two areas: one to be treated by using hydraulic fracturing (HF) and the
other to be treated using a conventional well (CW). The same injection fluid was to be introduced into
each. The two areas were sampled at the beginning of the project then again during treatment.

       Hydraulic fractures were created by injecting cross-linked gel at a constant rate into a lance-like
device composed of a casing and an inner  rod, both of which are tipped at one end with a hardened
cutting surfaces that form a conical point. A drive head at one end of the lance secures both the casing
and the rod. Individual segments of the rod and casing are 1.5m long and they are threaded together
as required by the borehole depth.

       During the field work, the lance was driven to depths of as much as 4 meters. The rod and point
were removed, leaving soil exposed at the bottom of the casing. Another device composed of steel
tubing with a narrow orifice at one end, was inserted into the casing. Water pumped into the device
formed a jet that cut laterally into the soil. The jetting device was rotated, producing a disc-shaped notch
extending 10 to 15 cm away from the borehole. A simple measuring apparatus, built from a steel tape
extending the length of the tube and making a right angle bend at the end of the tube, was inserted into
the casing to verify and measure the radius of the slot.

       Hydraulic fractures were created by injecting the cross-linked guar gum gel into the casing.
Injection rates of 60 to 90 liters per minute were used for the tests. Lateral pressure of the soil on the
outer wall of the casing effectively sealed the casing and prevented leakage of the slurry. The fractures
nucleated at the notch and grew away from the borehole.

        During a typical procedure to create the fractures, the onset of pumping was marked by a sharp
 Increase in pressure of the injection fluid to between 200 and 350 kPA (30 and 50 psi). This onset of
 fracture propagation, however, was marked by an abrupt decrease in pressure, with pressures in the
 range of 70 to 170 kPa (10 to 25 psi) during propagation. After one fracture was created, the rod and
 point were inserted and the lance driven to a greater depth where another fracture was formed.

        The conventional well was created by drilling a 10 cm borehole to a depth of 4 m.  This hole was
 filled with sand to a depth of 1.5 meter, a half inch PVC pipe was inserted, then sealed in place by filling
 the rest of the borehole with bentonite.

        The week after the fractures were created, continuous split spoon samples were taken to
 determine the location of the hydraulic fractures, to determine the soil stratigraphy and to study the
 chemical and microbial conditions in the soil. The borings were made at radial distances of 1.5, 3.2, arid
 5 meters with respect to the fractured and unfractured wells. Samples for BETX (benzene, ethyl
 benzene, toluene and xylene) were taken directly from the split-spoon and placed in 300 ml of methanol.
 The remaining sample was sealed in ziplock bags and placed in iced coolers for analysis of TPH (total
 petroleum hydrocarbons), moisture, and pH in the lab.

        Microblal populations were determined by aseptically removing 1 gram samples, sonicating to
 release the organisms from the soil, then plating on R2A medium incubated at 29°C. To determine the
 number of gasoline degrading microorganisms; in 1 gram, the samples were plated on non-nutritive salts
 medium and the plates incubated at room temperature in a gasoline-fume atmosphere. Microbial activity
 was determined by monitoring the hydrolysis of fluorescein diacetate (FDA). Fluorescein diacetate was
 dissolved in acetone at a concentration of 2 mg/ml. One gram of soil plus 0.5 ml of the FDA solution
 were added to 100 ml of 60 mM phosphate buffer (pH7.6). These were incubated on a shaker at 12°C
 for 24 hrs. The cultures are centrifuged, then filtered and the color development measured at 490 nm.

        Water containing oxygen and nutrients is currently being injected into the wells. The flow rates
 and pressures are being monitored. At 8 week intervals the site is resampled for chemical, physical and
 microbial conditions.


        Four hydraulic fractures were created in  the contaminated area (HF). The depth of each fracture
 was 2.3 m (HF2.3), 2.6 m (HF2.6), 3.2 m (HF3.2), and 4 m (HF4). We have estimated the general
 geometry along cross-sections through HF (Figure 1). The fractures appear to be roughly flat-lying to
 gently dipping toward the parent borehole. The  uppermost fractures at HF appear to have the steepest
 dip, roughly 30°, as it climbs from the parent borehole to the ground surface north of the borehole. The
 other three fractures at HF dip from approximately 30° within 1.5 m of the borehole, but then flatten to
 dips of 10° to 15° at greater distances on the northern side of the borehole.  None of the deeper fractures
 reached the ground surface.  Two fractures were discovered 3.2 m south  of HF and they were inferred to
 be the lowest two fractures, as shown on the crdss-section.  The geometry of the fractures is locally
 inconclusive due to lack of recovery.

       Creating the fractures produced broad domes at the surface, with maximum displacements of 12
to 23 mm, over areas roughly 9 to 14 m in maximum dimension. Most of the domes are roughly equant
 in plan, although the point of maximum uplift is almost always at a point other than the point of injection.
As a result, the fractures appear to be asymmetric with respect to the points of injection.

       The results of the chemical, physical and microbiological analyses of the initial soil condition are
complete.  The contaminant concentrations at the site were nonuniform but the whole area was

contaminated. For example, benzene ranged from a maximum of about 14 ppm to a minimum of 1 ppm.
Ethyl benzene ranged from 40 ppm to about 1 ppm. The pH of the soil was between 7.2 and 8.  Starting
soil moistures are in the range of 9 to 16%. The number of gasoline degrading and heterotrophic
microbes ranged between 104 and 105 CPU (colony forming units)/ gram soil.  .


       Hydraulic fracturing was shown to be a feasible procedure at this contaminated site. The size
and shape of the fractures were as planned. Enough information was gathered at the site in the initial
assessment to evaluate the post treatment effects of the hydrofracturing as compared to a conventional
injection well arrangement. The site conditions make it conducive to bioremediation (e. g. pH about
neutral, significant hydrocarbon degrading microbial population).  Significant progress is expected in the
coming months and an update will be given at the meeting.
                              FRACTURING   BOREHOLE
             Fill (crushed .limestone)
             Light Brown Silty Clay
             Olive Green Clay/No Clasts
             Light Grey Silty Clay with Rock Fragments
             Light Brown Stiff Mottled Clay with Rock Fragments
             No Sample Recovery
Fracture #
Figure 1.  Cross section showing stratigraphy and hydraulic fractures in the HF treatment area.


                  Guggilam Sresty,  Harsh Dev, and Joseph Chang.
          IIT Research Institute,  10 W. 35th Street,  Chicago,  II  60616

                                 Janet Houthoofd
            RREL, USEPA,  5995 Center Hill Road,  Cincinnati,  Oh 45224

       The wood preserving industry1 uses more pesticides  than any other
 industry worldwide (1).  The major chemicals used are creosote,
 pentachlorophenol, and CCA (copper, chrome and arsenate).   It is reported that
 between 415 to 550 creosoting operations within the United States consume
 approximately 454,000 metric tons of creosote annually.  When properly used
 and disposed off, creosote does nof: appear to significantly threaten human
 health.  However, due to improper disposal and spillage  at old facilities,
 creosote and other wood preserving chemicals have found  their way into surface
 soils.  Active wood preserving sites generate an estimated  840 to 1530 dry
 metric tons of hazardous contaminated sludge annually, which is  classified as

       Creosote,  obtained from coal tar,  contains a large number  of chemical
 components.  The three main families of compounds represented in creosote are;
 polycyclic aromatic hydrocarbons (PAH),  phenolic,  and heterocyclic compounds.
 Creosote is composed of approximately 85% PAHs,  10%  phenolic compounds and 5%
 heterocyclic compounds.  There are approximately a total of 17 PAHs present in
 creosote.   The four most prominent compounds belonging to  the PAH family  are
 naphthalene,  2-methylnaphthalene,  phenanthrene,  and  anthracene.   These four
 compounds  represent approximately 52% of the total PAHs  present  in creosote.
 There  are  approximately 12 different phenolic compounds  present  in creosote
 among which phenol is the most abundant,  representing 20%  of the total
 phenolics.   In addition,  the various isomers of  cresol represent about 30%  and
 pentachlorophenol (PCP) represents 10% of the total  phenolics.   There are
 approximately 13 different heterocyclic  compounds  present  in creosote.  Among
 these the  nitrogen containing compounds  are  the  most abundant, representing
 approximately 70% of the total heterocyclics.  The balance is distributed
 between sulfur and oxygen containing heterocyclics.

                 ;                 I                  '
      All  of  these compounds possess toxic properties  and  some of  them, for
 example, PCP,  when subjected to high temperature environments are  suspected
 precursors  in the formation of dioxins.

     In this  paper the results of  an ongoing,  USEPA  funded,  cooperative
 agreement(are described.   The purpose of  this  project is to  determine  the
 treatability  conditions for the removal  of wood  preserving  contaminants
 present in  soil  by in situ thermal -treatment.  The goal was  to find
 appropriate time and  temperature conditions  for  the  treatment of soils by the
 in situ radio frequency (RP)  soil decontamination process.    The  in  situ RF
 heating process  utilizes  electromagnetic  energy  in the radio frequency band to
 heat up the soil rapidly,  uniformly,  and  without .injection of heat transfer
media or on site combustion.   The in situ RF process can be used to heat the
 soil to a temperature range of 150°-200°C.     The contaminants are vaporized
 and or  boiled oat  along with  water vapor  formed by the boiling of native soil
moisture.   The gases  and  vapors  formed upon heating the soil are recovered  for
on site  treatment  by  means  of a  gas  collection system.,

      The feasibility of the in situ RF soil decontamination process was first
demonstrated for petroleum hydrocarbons at a site of a jet fuel spill (2).  In
this field experiment approximately 500 cu. ft. of sandy soil was heated to a
temperature range of 150-160° C.  It was demonstrated that 94 to 99 percent of
the aliphatic and aromatic hydrocarbons present in the spill site were removed
(2).  In various other laboratory feasibility studies, the treatment
conditions for the removal of the following contaminants has been established:
perchloroethylene and chlorobenzene from sandy soil (3), jet fuel from clayey
soil (4), PCBs from sandy/clayey soils (3), phenanthrene,  pentachlorophenol
and phenol from sandy/clayey soils (5).  All of these studies except the one
with jet fuel were done with clean soils which were spiked with the
contaminants in the laboratory.  In this paper we present the results of
feasibility studies performed with contaminated soil obtained from a wood
preservative site.                                        •   .


Full Scale Implementation;  The RF soil decontamination process is a two-step
process which operate simultaneously once the average temperature of the soil
exceeds 50° C.  These steps are:  heating of the soil, and vaporization and
recovery of the contaminants.

      In the first step of the process, the soil is heated to temperatures of
150° to 200° C by means of an electrode array inserted in bore holes drilled
through the soil.  Selected electrodes are specially designed to permit both
the application of RF power while collecting vapors by application of a vacuum
down hole.  The vapor collection system is an integral part of the electrode
array since vapor collection points are physically integrated and embedded in
the array.  A vapor containment barrier is used to prevent fugitive emissions,
and provide thermal insulation to prevent excessive cooling of the near
surface zones.

     Prior laboratory and field experiments (2-5) have shown that high boiling
contaminants can be boiled out of the soil at much lower temperatures than
their actual boiling point.  This occurs due to the presence of an
autogenously established steam sweep which helps to improve the rate of
vaporization of such high boiling materials.  Another phenomenon which
operates during in situ heating is the development of effective permeability
to gas flow.  The increase in permeability is confined to the heated zone,
thus creating a preferred path of gas and vapor flow towards the soil surface.

      The second step of the process is the collection, recovery, and on-site
treatment of the vapors and gases formed by heating of the soil.  The
collected waste gases are transported to an on-site treatment system.  The
first vapor treatment step is cooling and condensation of the vapors from the
gas stream.  The uncondensed gases are further treated to remove contaminants.
This treatment may consist of carbon adsorption, combustion in a gas-fired
afterburner, and/or gas scrubbing in an alkaline scrubber.  The specific gas
treatment steps used depend upon the nature and amount of contaminants
expected in the gas stream.

      The liquid phase is separated on site into two fractions: the aqueous
phase and the organic phase.  The aqueous phase is treated on site through a
carbon bed and a filter.  The organic phase is stored, pending ultimate
destruction at an approved treatment facility.

 Tgeatabilitv Study;  The soil treatability experiments were performed by
 heating a 3-ft column of soil packed into a 1.5 in. diameter, 4-ft long
 stainless steel pipe.  The pipe was connected at the top via heat traced
 tubing to a glass water-cooled condenser.  The outlet of the condenser was
 connected to a vacuum flask which was pre-charged with 50 to 70 mL of
 methanol.  The side-leg of the vacuum flask was connected to a wet-test meter.
 The flask was kept in an ice bath.

      The bottom port of the reactor was connected to a source of heated nitro-
 gen or superheated steam.  Zero grade nitrogen was obtained from a cylinder,
 heated through a heat traced line and delivered at the base of the soil col-
 umn.  When steam was needed, a three-way valve was used to pump water into the
 heat traced line.  The water was pumped by a positive displacement metering
 pump, capable of delivering 0 to 10 mL/min.   The temperature of both nitrogen
 and steam was adjusted to approximately match the average temperature of the
 soil in the reactor.  The soil column was heated by externally wrapped heating
 tapes.  Both internal and external thermocouples were used to make sure that
 the soil was at the desired temperature.

       The results of the treatability experiment were determined by analyzing
 and comparing the results of soil samples taken while the reactor was being
 packed and of treated soil removed .from the  reactor at the end of an
 experiment.   The variables being studied in  these experiments are the
 treatment temperature,  time,  flow rate of steam,  type of  flowing fluid sweep,
 viz., nitrogen versus steam and type of soil matrix (field soil  versus
 Standard Analytical Reference Matrix or SARM I  soil as prepared  by EPA).   In
 selected experiments mass balance will be made  by analyzing the  aqueous
 condensate phase collected in the water cooled  condenser.
                           TABLE 1.   EXPERIMENTAL CONDITIONS

Soil type
Soil weight, g.
Contaminants spiked

Treatment temp. , °c
Treatment time at temp., hrs.
Sweep Gas
Flow rate, L/min
Time, hrs.
Flow rate, L/min*
Time, hrs.
Experiment No.






*  at treatment temperature

      The experimental conditions for five experiments are summarized in Table
1 (additional experiments are underway).   All experiments were performed with

 soil  obtained from the wood treatment  site.   In experiments 2 to  5, Aroclor
 1242  was  spiked on the soil to determine the  removal efficiency of PCB by the
 in  situ process.
Treatment Temperature, ° C
Treatment Time at temp., hr
Benzo ( b ) f luorant hene
Benzo ( k ) f luoranthene
Benzo ( a ) pyrene
I ndenopyr ene
D ibenzo ( a , h ) anthracene
Benzo ( g , h , i ) perylene





Percentage Removal
Experiment No.
      The results of experiments 1 to 5 are summarized in Table 2.   In this
table the percentage removal for PAHs and PCP is presented.  The results show
that treatment at a temperature of 200 to 230° C for a period of 70 hr. is
sufficient to remove the PCP and the three ring PAHs to their analytical
detection limit.  Thus nearly 100 percent removal of these compounds from the
soil can be achieved.  High removal efficiency was also obtained for pyrene, a
four-ring PAH.  All of these compounds have a normal boiling point  less than
400° C.  For other compounds with higher boiling points and having  four or
more rings, the removal efficiency was (lower.  In experiments 2 through 5,
Aroclor 1242 was spiked into the soil.  The initial concentration of Aroclor
was 1078, 1150, 1240, in experiments 2 to 4, respectively.  The final Aroclor

 concentration in the soil from these  three experiments was 48, 14,and 34 ppm.
 Thus the  average removal of the Aroclor  in the three experiments was 95.6,
 98.8 and  97.3 percent.   Thus treatment at 230° C can reduce the PCB
 concentration below 25  ppm.   Additional  analyses of the condensate are being
 performed to  close the  mass balance for  the PAHs, PCP and the Aroclor.  More
 experiments are  being done on SARMfl  soil to provide comparative data for the
 standardized  soil.
      The results of the treatability experiments performed have shown that
heating of soil to  a temperature range of 200° to 230° C is sufficient to
remove PCP and all  the  four-ring PAHs with boiling .point of less than 400° C.
As before, it was again demonstrated that it is not necessary to heat the soil
to the boiling point of the pure component in order to obtain substantial
removal from soil.  The results have also demonstrated the feasibility of the
removal of Aroclor  1242 from soil in the temperature range of 200-230° C.


1.    Mueller, J. G., P. J. Chapman, and P. HapPritchard.  Creosote
      Contaminated  Sites.  Environmental Science and Technology, 23(10):1179-
      1201, 1989.

2.    Dev, H., Enk, J., Sresty, G., Bridges, J.  In Situ Decontamination by
      Radio Frequency Heating—Field Test.  IIT Research Institute.  Final
      Report C06666/C06676.  Prepared for USAF, HQ AFESC/RDV,  Tyndall AFB,
      Fla., May 1989.

3.    Dev, H., J. Bridges, G. Sresty, J. Enk, N.  Mshaiel, and M. Love.  Radio
      Frequency Enhanced Decontamination of Soils Contaminated with
      Halogenated Hydrocarbons.  EPA/600-2-89/008.  U.S. Environmental
      Protection Agency, Cincinnati, Ohio, 1989

4.    Dev, H., and G. Dubiel.  Optimization of Radio Frequency (RF) In Situ
      Soil Decontamination Process.  Draft Final  Report, IITRI Project No.
      C06691.  ANL Contract No. 83482402.  June 1990.

5.    Sresty, G.C., Dev, H., Gordon, S.  M., and Chang,  J.  Methodology for
      Minimizing Emissions by Remediation of Environmental Samples? Containing
      Wood Preserving Chemicals, Draft Final Report, IIT Research Institute.
      US EPA Contract No.  69-D8-0002, Work Assignment  No. 22,   IITRI Project
      No.  C06693C022.

                                          Diana R. Kirk
                                            U.S. EPA
                              Risk Reduction Engineering Laboratory
                                     5995 Center Hill Avenue
                                     Cincinnati, Ohio 45224
                                         (513) 569-7674
                                         Paul L Bishop
                         Department of Civil and Environmental Engineering
                                    741 Baldwin Hall (ML #71)
                                     University of Cincinnati
                                   Cincinnati, Ohio 45221-0071
                                         (513) 556-3675
   One of the major concerns with the solidification/stabilization (S/S) process for final containment of
hazardous wastes or other teachable materials is the uncertainty relative to long term stability of the
material in the environment, where it will be exposed to many influences which may cause deterioration.
The potential for and degree of weathering needs to be evaluated.

   This research addresses the potential weathering of waste forms and the effects of aging and
weathering on leaching from these waste forms.  The overall objectives of this research are to assess the
long-term durability of stabilized/solidified wastes from Superfund sites and to verify existing
durability/leaching models.  Specific objectives include the development of accelerated aging and
weathering tests for determining long-term durability, evaluating the influence of wet/dry cycling on
durability and leaching characteristics,  evaluating the influence of waste form cracking on sample
porosity and permeability, and use of the results obtained to validate existing durability and leaching
  The stabilized/solidified waste samples were prepared from sludges containing .02 M concentrations
of lead nitrate, sodium arsenite and cadmium nitrate with a water/binder ratio of 0.7.  The sludge was
solidified with different waste-binder ratios of portland cement, iime/flyash, and kiln dust using ASTM C-
109 into 3" diam x 6" cylinders, 2" x 2" x 2" cubes, and 3" diam x 1" disks and cured for 28 days.  These
samples were then aged in weathering chambers, which allow specimens to be exposed to static
conditions (elevated temperatures and/or pressures and/or submersions) and recirculating sprays for
simulated times of 20, 50, and 100 years.  The set of control samples (not aged) and the test samples
(aged) were then tested for porosity, permeability, leach tested (TCLP, ANSI 16.1, and Sequential
Leaching), wet/dry cycles, unconfined compressive strength, and acid weathering.

    Stabilized/solidified samples were subjected to Arrhenius aging techniques to accelerate the aging
 process.  Accelerated aging refers to accelerating the conditions a treated waste will experience during
 the aging process. Many environmental factors may affect a material over its lifetime, such as changes
 due to wet/dry, wind and rain erosion and weathering or erosion due to groundwater action.  The
 procedure developed for artificially aging the waste forms is based on the Arrhenius model. The
 equivalent age function is based on the activation energy of the material.

    The age function, known as the Arrhenius equation is:
t. = service time
ta = accelerated time
Ea = activation energy
k  = Boltzman's constant
Ts = service temperature
Ta = accelerated temperature
    This formula provides a means for determining the equivalent age (service time, ts) a specimen would
experience at a given natural temperature (service temperature, Ts).  These times and temperatures are
modelled as accelerated temperature (U for a given accelerated time (tj for the material specific
activation energy (£„).

    In this research, Thermogravimetric Analysis  (TGA) was used to determine the waste specific kinetic
parameters for the Arrhenius aging equation. Thermogravimetry measures the weight changes in a
sample as a function of temperature or time. The mode of thermogravimetry used for this study is
known as dynamic thermogravimetry, in which (different sample types were heated  in an environment
whose temperature changed in a pre-determined manner at a linear rate.  The resulting mass change
versus temperature curve provided information concerning the thermal stability and composition of the
sample. This information was then used to determine kinetic parameters of the material, specifically the
activation energy.

    Cement-based immobilization systems rely heavily on pH control for stabilization of metal
contaminants. Over time, acid in leachants in contact with the waste form will penetrate the  specimen
and gradually leach waste matrix materials and |metals into the surrounding environment.  An intensive
study was undertaken to identify the leaching rnechanisms involved by evaluating the pH profiles within
leached specimens and the physical and chemical properties of the leached material. The pH profile
along the acid penetration route in the cement-based waste forms was identified by splitting the samples
and applying various pH color indicators. The effect of acid attack on density and  porosity changes and
pore size distribution was also studied.

    Monolithic and crushed test specimens which have been subjected to accelerated aging  procedures

based on the Arrhenius model were acid weathered using a leachant with an acidity comparable to that
expected to be encountered by the waste form over the period of time simulated by the aging process.
The monoliths were suspended in an extractor at a 10:1 (g leachant/sq cm monolith surface area) ratio
for 48 hours. Crushed samples were extracted for 48 hours at a 20:1  (W/W) leachant: solid ratio.  Aged
samples were analyzed for leaching depth, leached zone porosity and wet/dry resistance, and the
leachate is analyzed for contaminants.  The resulting samples, which simulate aged and weathered
waste forms, were then subjected to various leaching tests, including the TCLP and the ANSI 16.1  test to
determine whether the aged specimens leach differently than control samples.

   The possibility of leaching hazardous substances from solidified wastes in land disposal sites is
increased if the solidified monolith is fractured during weathering.  It is, therefore, desirable to determine
if the monolith fractures during weathering and, if it is fractured,  what is the extent of fracture. The
method used to determine the amount of surface fracture was laser holographic interferometry.
Holograms were made by recording a diffraction grating on a photographic plate.  The interference of a
reference beam and an object beam created by a laser beam created the fringe patterns  on the
photographic plate. Cracks were seen in the hologram as a discontinuity in the fringe pattern.  The
object (sample), optics, and plates were placed on an isolation table consisting of a 3000  pound granite
table top.  Epoxy dye injection was used to determine the inner fractures and cracks.

   Another technique used to evaluate deterioration of solidified wastes include resonance frequency
and pulse velocity.  This was done in collaboration with the Department of Energy  (DOE)  to evaluate this
technique for assessing waste form durability.  The evaluation of this parameter required the
determination of the natural frequency of the specimens after each aging cycle.  In resonance frequency
testing a sample was excited by the application of an ultrasonic wave generator. The frequency of the
waves was varied until the specimen vibrated in a resonant mode.; As specimens sustain damage, the
resonant frequency changes and this change can be used to assess the damage.
    Thermogravimetric Analysis (TGA) was run on pieces from three crushed cylinders of waste forms
made from a sludge containing lead nitrate, sodium arsenite and cadmium nitrate. Each sample was
analyzed under different physical conditions (small solidified pieces or as powder); under different
moisture conditions (saturation, air-dried, dried at 60° C and dried at 110° C); and for four different
temperature ramps from 2° C/min to 16° C/min, in order to investigate the effect that the physical
properties of the samples exhibited on the resulting TGA analysis.

    Using the Arrhenius Equation and the kinetic parameters determined from the TGA data, an
accelerated aging schedule was developed. The Arrhenius equation uses the activation energy (EJ
found from the TGA, Boltzman's constant (k), and a given  accelerated operating temperature (TJ for the
aging chambers.  The service time (t.)  was chosen to model two different times in the future, 50 and 100
years.  The service temperature to be modelled was taken from the average temperature in the greater
Cincinnati area over the last 100 years (Ts = 54.6° F).

    The time of contact of a waste form with leachant could significantly alter the potential for leaching
because it results in increased porosity and creation of a chemically altered surface layer. The pH in the
surface altered layer was found to vary from 5.0 to 6.0, which is very close to the pH in the bulk

 leachate. A reacting zone, where the pH abruptly changed from 6 to 12, sharply divided the altered
 surface layer from the remaining unleached waste form or "kernel".  The reacting zone was white in color
 and was about 100 microns in width for the samples with 0.6 water-cement ratio leached in 0.4 N acetic
 add solution for a total period of 29 days (Figure 1). SEM/EDX analysis indicated that in the surface
 layer,  most of the calcium and the stabilized metals were removed by the leachants. The metal
 contents of the kernel, however, were very close to those of the original material.  It was believed that
 the leaching boundary was formed by the inwarg1 diffusion and reprecipitation of calcium hydroxide
 crystals in front of the acid.                    i
	 Leached Cement—Based Waste Form
Leached  Layer	-|	 Unleached  Kernel
               Acetic  Acid

                             • Solid/solution
                      White Remineralization
                      Region (100 microns in  width)
           Figure  1.   Schematic profile,of  a leached  cement-based waste form.
    The porosity of the kernel was essentially the same as for the unleached controls, but the porosity of
the leached layer increased significantly. The pore distribution in the kernel was the same as in the
unleached samples, but the leached zone was significantly different.  The gel porosity of the leached
layers increased greatly due to the dissolution of calcium silicate hydrate matrix.
                                             i           '                    -                   ' '

    The leaching of metals was controlled by the acidity available in the leachant.  Dissolution of alkaline
materials left a silica-rich layer on the surface of khe cement-based  waste from. This surface layer
exhibited different properties than those of the unleached material.  The surface layer had a higher water
content, was lighter weight, and was soft and friable.  Furthermore, the abundant silicate content on the
solid surface detained a portion of the leached metals, while they moved through the leached layer into
bulk solution.  The leaching mechanisms of metals was idealized as five steps: (1) mass transfer of acids
from bulk liquid to solid surface,  (2) transport of acids through leached layer, (3) diffusion-controlled fast
dissolution reactions at leaching  boundary, (4) transport of metals through leached layer, and (5) mass
transfer of metals from solid surface Into bulk liqbid.

   The leaching of metals is a consequence of acid penetration. The distance from the solid/solution
interface to the front of the leaching boundary can be regarded as the depth of the leaching zone, where
the metals dissolve and diffuse out of the waste form.

   The position  of the leached layer can be predicted by knowing three measurable factors- the acidity
consumed in the leachant, leach time, and the buffering capacity of the waste form.  By knowing the
leachable fraction of metal contaminant,  the total amount of metal leached can be estimated from the
thickness of the  leached layer.

   These studies have shown that leaching is directly correlated to the amount of acid in contact with
the waste form, and that the leaching front moves progressively into the sample rather than being
diffused throughout the waste form depth.  Further studies indicate that the amount and extent of
leaching is essentially the same for samples exposed  to a weak acidic leachant over a long time period
as for a strongly acid leachant over a short time interval. Thus, the effect of acid leaching over a 50 or
100 year period  can be simulated by using proper strength acid leachant, equivalent to that specimen
would  see over the exposure period.

   Sample porosity and pore size distribution is very important in determining the degree of leaching
that will occur in a waste, since leaching is largely controlled by the amount of available surface area.  A
study conducted on solidified/stabilized  fly ash and flue gas desulfurization (FGD) sludge wastes
showed that acetic acid leaching increases pore volumes and  pore sizes.  It was found that pore
structures varied depending upon the wastes used and the solidification mix formulations tested.  The
higher the alkalinity in a sample, the greater the change of pore structure due to  leaching.  Changes in
pore structure were primarily due to leaching of calcium hydroxide, resulting from the attack of hydrogen
ions in the leachant. These findings essentially coincide with the porosity results for the metal sludge
used in this project.

    Future work will include the testing of radioactive/mixed waste samples obtained from  DOE for
utilization in the  weathering chambers.  Many ideas about optimum S/S techniques have originated from
actual laboratory investigations and use  of chemical and physical tests, but there has never been a
concrete relation between field leachate  quality and laboratory leachate quality. The application  of leach
tests in conjunction with weathering and aging techniques on  field  waste samples will provide valuable
data on existing short-term laboratory tests.  This will aid in devising  better techniques for making
predictions on the long-term durability of S/S waste forms.

                                        Marta K. Richards
                                  26 West Martin Luther King Drive
                                      Cincinnati, Ohio 45268
                                          (513) 569-7783

                                      Donald J. Fournier, Jr.
                                       Acurex  Corporation
                                  Environmental Systems Division
                                        NCTR Building 45
                                    Jefferson, Arkansas 72079
                                          (501)  541-0004
     In response to the need for data on the partitioning of trace metals from hazardous waste
 incinerators, an extensive series of tests was conducted in the summer of 1991 at the USEPA
 Incineration Research Facility (IRF) in Jefferson, Arkansas. These tests were conducted in the IRF's
 rotary kiln incinerator system (RKS) equipped with a pilot-scale Calvert Flux-Force/Condensation
 scrubber as the primary air pollution control system (ARCS). The purpose of this test series was to
 extend the data base on trace metal partitioning and to investigate the effects of variations in incinerator
 operation on metal partitioning. Another objective was to evaluate the effectiveness of the scrubber for
 collecting flue gas metals. This series is a continuation of an ongoing IRF research program
 Investigating trace metal partitioning and ARCS collection efficiencies. Two previous test series were
 conducted using the RKS equipped with a venturi/packed-column scrubber and a single-stage ionizing
 wet scrubber.

     The primary objective of this test series was to  determine the fate of six hazardous and four
 nonhazardous trace metals fed to the RKS in a synthetic, organic-contaminated solid waste matrix. The
 six hazardous trace metals used were arsenic, barium, cadmium, chromium, mercury, and lead. The
 four nonhazardous trace metals-bismuth, copper, magnesium, and  strontium-were included primarily to
 supply data to evaluate their potential for use as surrogates.  The test variables were kiln exit gas
 temperature, waste feed chlorine content, and  scrubber pressure drop. The test program objectives
 were to identify

     • The partitioning of metals among kiln ash, scrubber liquor, and flue gas,

     • Changes in metal partitioning related to variations in kiln exit gas temperature and waste feed
       chlorine content,                     ;                                                .

     • The efficiency of the Calvert scrubber for collecting flue gas metals, and

     • The effects of scrubber pressure drop on metal collection efficiencies.

    The  IRF RKS consists of a rotary kiln primary combustion chamber, a transition section, and a fired
afterburner chamber. The refractory lined kiln is 2.5  m long with an  internal diameter of 1.0 m.  The
afterburner chamber is  also lined with refractory and measures 3.0 m long by 0.9 m in diameter.  For
these tests, both the kiln and afterburner were fired on natural gas.  Total heat input to the kiln  varied
with test conditions, ranging from 200 to 580 kW (0.7 to 2.0 MMBtu/hr).  Calculated gas-phase residence
time through the kiln and afterburner sections averaged 2.3 seconds.
    The  main components of the Calvert scrubber ARCS used during these tests were the
condenser/absorber, Calvert Collision Scrubber,™ entrainment separator, wet electrostatic  precipitator,

caustic tank and injection pump, and variable-speed induced draft fan.  A schematic of the scrubber
system is shown in Figure 1.  In its normal configuration the Calvert scrubber pilot plant also includes a
quencher/saturator and a cooling tower.  However, these components were not used for this test
program because their functions were equivalently met by the existing RKS spray quench and closed-
loop heat exchanger.
          FROM IRF
               PUMP  CONDENSOR
                                                                                 (VARIABLE SPEED)
                        Figure 1. Schematic of the Calvert scrubber system.

    The combustion gas exiting the afterburner was saturated and cooled by the IRF spray quench to
approximately 82°C (180°F), then directed to the Calvert scrubber system.  The first component of the
Calvert scrubber is the condenser/absorber, which is designed to sub-cool the flue gas to about 50 °C
(122°F) and to scrub acid gases. The condenser/absorber is followed by the Collision Scrubber.™ The
Collision Scrubber™ splits the flue gas into two streams then uses a head-on collision to create fine
droplets and a large surface area to enhance the removal of paniculate and remaining acid gases as the
flue gas passes through the venturi. The pressure drop through the scrubber is controlled through the
use of a variable speed induced draft fan, which provides an operating range of 7.4 to 17.4 kPa (30 to 70
in WC).  A three-stage entrainment separator follows the Collision Scrubber™.  For this test series, Calvert
Environmental installed a down-flow, tube type wet electrostatic precipitator with an entrainment
separator between the first entrainment separator and the induced draft fan. Scrubber liquor collected in
the sump of the condenser/absorber was pumped to either the IRF heat exchanger or quench system
recirculation tank.

    The synthetic waste fired throughout the test program consisted of a mixture of organic liquids
added to a clay absorbent material. The base solid material was a calcined clay sold commercially as a
granular absorbent for spill  cleanup. The main components of the clay are hydrated  aluminum-
magnesium silicate, free silica, dolomite, and calcite. The organic liquid base for the synthetic waste
consisted of toluene with varying amounts of tetrachloroethene and chlorobenzene added to provide a
range of synthetic waste chlorine contents. Waste chlorine content in the combined feed was varied
from zero (no chlorinated organics added) to nominally four percent.  After mixing, the clay/organic
mixture remained a free flowing solid, similar to the unspiked clay absorbent. The synthetic waste was
continuously fed to the rotary kiln via a screw feeder at a nominal rate of 63 kg/hr (140 Ib/hr)  of which
approximately 14 kg/hr (30 Ib/hr) was the organic liquid matrix.  For all tests, the kiln rotation rate was
held  constant to provide a solids residence time of about an hour.

     0™o «it    ?!,    H.estl excef?t chromium and magnesium, were fed to the kiln by metering an
        S £  « S°l  iu" ? ,theTmetals Into the clay/°raanic liquid mixture at the screw feeder, just prior to
      £ ±25"t0  he WrV Tt? !fSt meta'S Were added to the sPikin9 solution as sol^le ni rate salts,
                S" °-f arsenicr W,hich was added as As*°3- Tne sPjke so1*'™ was metered at a rate that
     on        fol|owmg nominal synthetic waste feed concentrations  in mg/kg: As-35; Ba-420- Bi-400-
       ' ~u'425: prb-5°:  H9-5? Sr-430.  Chromium and magnesium are native to the clay absorbent at  '
  concentrations of about 50 mg/kg and 2 percent, respectively, and so were not spiked.

      The test variables  were kiln exit gas temperature, chlorine content of the synthetic waste feed and
  Calveit scrubber pressure drop.  The test program consisted of 11 test points, with each parameter
  varied over three  levels. Achieved conditions for the test variables are shown in Table  1  Taraet kiln exit
  gas temperatures were 538°, 816°, and 927°C (1000°, 1500°, and 1700°F). Target feed chlSrine
  concentrations were 0,  1, and 4 percent.  Thei scrubber pressure drop for Tests 1 through 9 was held
  asTiTn^                          Test points 10 and 11 were at the same nominal condftons
  as test point 8, but with scrubber pressure drops of 8.7 and 17.4 kPa (35 and 70 in WC), respectively
  All tests were performed at the same nominal afterburner exit flue gas O2 (9 percent) and afterburner exit

                                             e kiln                           '
                                    TABLED. TEST CONDITIONS
                               Average Kiln Exit

                               Gas Temperature
  Waste Feed

Chlorine Content
  Pressure Drop

(kPa)      (in WC)
     The sampling and analysis protocols were designed to track the partitioning of the test metals
among the RKS discharge streams (incinerator ash, scrubber liquor, and flue gas).  For each test
composite samples of the clay/organic liquid mixture, aqueous metals spike solution, kiln ash  and
scrubber liquor were collected. The feedrates and total quantity fed of the clay/organic liquid mixture
and the metals spike solution were carefully noted.  Kiln ash weights and scrubber liquor volumes were
also determined for each test.  The flue gas was sampled for metals at the quench and scrubber system
exits using a Method 101A train for mercury and a Method  5 train modified for multiple metals capture
for the remaining metals.                   ,                                             ^

     Sample preparation and analysis methods documented in EPA SW-846 were used for most
ffIIP ^Zherdig,fst.ion and ana|ysis of samples for mercury were in accordance with the procedures of
Method 7470 for liquid samples and Method 7471 for solid samples, with analysis by cold vapor atomic
absorbtion spectroscopy. Solid samples analyzed for the remaining test metals were digested following
the procedures of ASTM Method E886, Method A. The samples were fused in a flux containing a 4 to 1

ratio of lithium metaborate and lithium .tetraborate, followed by a final dissolution of the melt in dilute HCI.
The liquid samples were prepared for metals analysis in accordance with the procedures of Method
3010. Metals analysis was primarily by ICAP spectroscopy in accordance with the procedures of Method
6010, although graphite furnace atomic absorbtion spectroscopy in accordance with Methods 7060 and
7000 were used to analyze most samples for arsenic and bismuth, respectively.


Note:  At the time this abstract was prepared, the only laboratory data received were for samples
       analyzed for mercury.  However, it is anticipated that data on the remaining metals will be
       received in time for presentation at the symposium.

    Table 2 summarizes the mercury partitioning as a percent of the mercury fed. For all tests  mercury
concentrations in the kiln ash were below detection limits of 0.1  mg/kg. This is expected based on
mercury's high vapor pressure.  Table 2 shows that mercury recovery in the flue gas at the quench exit
ranged from 17 to 113 percent of the mercury fed, averaging 66 percent.  It is interesting to note that
although the recovery of mercury in the quench flue gas was good, the downstream recovery in the
scrubber liquor and scrubber exit flue gas was much lower.  An explanation for this  observation is
provided by Figure 2, which shows the mercury partitioning to the scrubber liquor as a function of the
waste feed chlorine content. For the three tests with no chlorine in the waste feed, mercury
concentrations in the scrubber liquor were  reported below detection limits of 0.004 mg/L. With
increased feed chlorine content to about 0.6 percent, mercury partitioning to the liquor increased to
about 7 percent of the mercury fed. Mercury partitioning to the liquor  increased to approximately 30
percent with a further increase in waste feed chlorine content to about 3.5 percent.  In the case  of no
chlorine in the waste feed, mercury is expected to be found  in the flue gas in its elemental form or as
mercuric oxide.  Both are practically insoluble in water, but would still be expected to be scrubbed from
the flue gas at the low temperatures reached in the Calvert scrubber. However, once collected  in the


                     Mercury Partitioning (% of mercury fed)  Mass Balance Closure (%)
Waste Feed Quench Scrubber
Chlorine Exit Exit

< 1.2
< 0.9
< 1.0
< 1 .0
< 1.0
< 0.8
< 1.1
< 1.2
< 1.1
Flue Scrubber
< 1.4
< 1.8
< 1.3
< 1.0
Around Kiln
Ash and
Quench Exit
Flue Gas
Around Kiln
Ash and
Efficiency (%)
> 99
80 .
  * Calculated as a percent of mercury fed using detection limit values for samples reported below

    detection limits.
  + NA - Data not available.

 scrubber liquor, these insoluble forms of mercUry likely settled to the bottom of the liquor storage tank
 and were not collected when the liquor sample was taken, even though the storage tank was mixed
 before the sample was collected.  For the tests: with chlorine in the feed, mercuric chloride may have
 formed in the flue gas. Mercuric chloride is soluble in water and is more likely to be collected during
 sampling of the scrubber liquor.  The scrubber liquor partitioning data further suggests that the
 conversion to mercuric chloride was directly related to the amount of chlorine available.
                                   Waste Feed Chlorine Content (°/
        Figure 2. Mercury partitioning to the scrubber liquor versus waste feed chlorine content.

     Table 2 also shows the efficiency of the Calvert scrubber for removing mercury from the flue gas.
Scrubber efficiencies were determined by comparing the emission rate of mercury measured at the exit
of the quench and at the exit of the Calvert scrubber system. Thus, no credit is given for removal by the
quench.  Collection efficiencies ranged from 58 to greater than 99 percent, averaging 79 percent.
Comparing Tests 10 and 11  with the remaining tests shows no apparent relationship between scrubber
pressure drop and collection efficiency over the range tested.  Measured mercury flue gas
concentrations ranged from 0.034 to 0.21 mg/dscm at the quench exit and from less than 0.001 to 0.028
mg/dscm at the scrubber exit.


     Although most of the metals data were not [received from the laboratory in time for this abstract, the
following conclusions can be made based on the mercury data received to date.

     •  As expected, mercury was volatile and was not found above detection limits in the kiln  ash.

     •  The recovery of mercury in the scrubber liquor increased directly with increased chlorine content
       in the waste feed. Insoluble elemental mercury or mercuric oxide are the expected forms in the
       flue gas for the tests without chlorine, wfiile the presence of soluble mercuric chloride is
     •  suspected in cases with chlorine present.

     •  Calvert scrubber collection efficiencies for mercury ranged from 58 to greater than 99 percent,
       averaging 79 percent.  These efficiencies exclude any contribution by the quench for collecting

                Engineering  Analysis of Metals Emissions
                     from Waste Incinerators  Field Data

                           R. G. Rizeq, W. Clark, and W. R. Seeker
                      Energy and Environmental Research Corporation
                                18 Mason, Irvine, CA 92718

                                   To be presented at the
                           18th Annual RREL Research Symposium
                              Cincinnati, Ohio, April 14-16, 1992
                                EXTENDED ABSTRACT

       Hazardous metals emitted from waste combustion devices pose a significant risk to human
health. In recognition of this, EPA/RREL has initiated a study to collect and evaluate all possible metal
emissions information from all combustion sources.  This paper is a summary of this ongoing study.

       The EPA has established risk-based limits on emissions of metals from waste combustion
systems.  These limits are established in the form of regulations for boilers and industrial furnaces firing
hazardous waste and in the form of permitting guidelines for hazardous waste  incinerators. The limits
can be quite restrictive and can often be the limiting factor on the  design of air pollution control devices
for such facilities or on the types and quantities of wastes which can be burned. Over the past several
years, a significant body of data has been accumulated on metals emissions from full scale waste
combustion devices including:

       •       municipal solid waste incinerators,
              sewage sludge waste incinerators,
              hazardous waste incinerators,
              boilers and industrial furnaces,
              medical waste incinerators,  and
              mixed waste incinerators.

In addition, a number of laboratory and pilot scale studies on metals emissions and control have been
conducted.  These data have been collected from tests with varying degrees of control, data quality,
and completeness of reporting. Often there has been little  attempt to analyze the data beyond the
specific goals for which each test was conducted. Additionally, there have been few attempts to collate
the data and analyze it as a single unit.

Scope and Advantages of this Study

       This presentation describes the analytical efforts of a project to assemble all available data on
metals emissions from waste combustion devices into a single data base, and  to analyze the,data in an
attempt to isolate and explain the fundamental parameters which control metals emissions from waste
combustion devices.  In particular, several concepts/questions based on fundamental mechanisms or
on common observations of metals emissions from combustion systems are proposed and examined  in
light of the data:

              Does metals volatilization dominate  partitioning ?
              Is volatilization controlled by combustion zone thermodynamic  equilibrium ?
              Does the metal feed rate control metals emissions ?

                Does the air pollution control device determine emissions ?

 Data and theory are analyzed and arguments are advanced to support and/or refute some of these
 concepts and their applications to metals behavior in waste combustion systems.

        This analysis will help identify the factors which control metals emissions from waste
 combustion devices.  Understanding of these factors and their implications will ultimately help the
 regulatory and permitting authorities to:

                set flexible testing procedures for facilities to show,compliance with emission  limits,
                determine reasonable default values for estimation of air pollution control device
                efficiency, and
        •       assess the maximum achievable control technology for metals emissions from waste
                combustion devices.

 In addition, the analysis will help the designers, and operators of waste combustion systems to minimize
 metals emissions.                          •


 The approach is to apply the current understanding to develop hypotheses on metals behavior based
 on fundamental concepts and common observations. These hypotheses are then examined against
 data relating metals emissions to waste characteristics and design/operating parameters. The steps to
 this  approach are:                          ;
                                           I                   '                     '
               determine the fundamental concepts/questions of metals behavior that need to be
               investigated and correlated to data,
               gather data and develop a data base,
               analyze data in light of the fundamental concepts/questions proposed and link metals
               emissions data with theory,
               identify correlations  with design and operating parameters, and
               draw conclusions from the analysis and provide recommendations for further work or
               testing improvements.        j

 Availability and Assembly of Field Data

       A data base is being established through collection of experimental data and fundamental
 studies taken from various types of waste incinerators equipped with different types of air pollution
 control devices (APCDs)  at various operating conditions.  The database includes detailed information of
 each facility's hardware and operating parameters such as:
               size and type of incinerator,
               type of APCD,                ;
               primary and secondary combustion zone temperatures,
               uncontrolled metals emissions,
       •       controlled metals emissions with detailed APCD operating parameters,
       •       feed rates of all wastes and metals,
       •       waste chlorine  content, and
       •       other pertinent information.

The database allows the data to be easily retrieved and classified to  aid comparison and analysis of the

behavior of metals and other pollutant emissions from various facilities under selected operating
Data Analysis

        This section presents the fundamental points of investigation in light of their relation to the
engineering analysis of field test data. Discussion focuses on:

               Statement of the fundamental concept of metals behavior
               Theoretical background
               Results from the engineering analysis of field data
        •       Conclusions / recommendations

The key fundamental concepts will highlight what influences  metals emissions in practical waste
combustion systems.  Therefore, to help set a base for a unified understanding of metals partitioning
behavior in various types of incinerators, several concepts can be developed.  Some detail of each
concept follows.

Importance of Volatilization

        The influence  of variation in volatilization temperature on the removal of metals from the bottom
ash from field data is analyzed. Additional data are available for the impact of temperature on metals in
kiln ash and fine particulates,  and on the flyash enrichment of volatile metals.  It is concluded that
metals volatilization dominates partitioning.  Notable exceptions are arsenic under certain conditions.

Metals Emissions may be Predicted by Equilibrium Thermodynamics

        If thermodynamic equilibrium  is controlling, then important parameters may include:

               Combustion zone temperature: Temperature strongly influences the emissions of
               volatile metals.

               Amount of chlorine  in waste: Chlorine  in waste increases emissions of most metals.

               Metals volatility:  Metals emissions are related to their volatility if the metals
               concentration  in the combustion gas is the equilibrium saturated concentration. Data
               for the emission concentrations of some metals as a function of metals volatility ranking
               are available from trial burns of several hazardous waste facilities including Aptus, 3M,
               Bros, and DuPont.

        Field  data shows that  trends in metals emissions  are consistent with the assumption of
combustion zone thermodynamic equilibrium. Effects of temperature and chlorine on metals emissions
can also be thermodynamically predicted.

Do Metals Feed Rates Control Metals Emissions ?

        If a metal's concentration is undersaturated in the combustion gas, due to the vaporization of all
of the metal fed to the combustor, then the metal's emission  rate is dominated by the feed rate of the
metal rather than its saturated concentration. Theoretical arguments and figures for the expected
behavior of metals emission rates as  a function of metals feed  rates are discussed.  A comparison plot,
generated from field test data, for metals emission rates as a function of feed rates shows that metals

emissions are influenced by feed rates when all of the metal vaporizes (i.e., the metal is unsaturated in
the combustion gas).                          .                                 ,

How Much are Metals Emissions Dictated by APCDs ?
        There are several types of air pollution control devices (APCDs).  Theoretical descriptions of
key APCDs are discussed and field test data for control efficiencies of various types of APCDs are
presented including:

        •       Particulate emissions from trial burns of several hazardous waste facilities with diverse
               APCDs including ESPs, baghouses, Venturis, scrubbers, and HEPA filters.

        •       Metals control efficiencies from various APCDs installed at municipal waste incinerators.

        •       Scrubber efficiency versus volatility temperature of several metals in a rotary kiln.

               Venturi/packed bed scrubber control efficiency as a function of volatility temperature of
               various metals for data obtained from the Mobay/EPA trial burn test program, 1988.

               Baghouse control efficiency versus metals (ranked according to their volatility)  from the
               Aptus/EPA trial burn test program, 1989.

        In conclusion, analyses of the above mentioned data indicate that air pollution control devices
dictate emissions.

Recommendations for Necessary Work                       .

        Remaining research issues include:

               Metals management requires more detailed understanding of the impact of systems
               design/operation and waste parameters on metals behavior.

               Important data gaps:         '



Kinetics of metals transformation under conditions simulating waste combustion.
Hexavalent chromium chemistry.
Arsenic volatilization chemistry.
Innovative techniques to change the size distribution of metals.
Fragmentation and fly ash particle size and dependence on waste stream
Interactions of metals with Ca, Al, Si within burning beds of metal containing
Impact of physical/chemical of the waste on the behavior of metals.
High temperature liquid metal viscosity.
Monitoring strategies for fine particulate matter and metals emissions.
Waste characterization techniques for metals behavior.
       Support for this project provided by the'U.S. EPA, Risk Reduction Engineering Laboratory
(Project No. 68-CO-0094) under the direction of Dr. C. C. Lee is gratefully acknowledged.

                                        David A. Carson
                                           U. S. EPA
                              Risk Reduction Engineering Laboratory
                                26 West Martin Luther King Drive
                                     Cincinnati, Ohio  45268
                                        (513) 569-7527

                                      Thomas A. Janszen
                             IT Corporation - Environmental Programs
                                      11499 Chester Road
                                     Cincinnati, Ohio  45246
                                        (513) 782-4700
       This study was initiated to investigate the effects of municipal waste combustion (MWC) ash
monofill leachate on lining components of an MWC monofill.  This includes geosynthetic materials and
natural clay (soil) liners. The ability of these materials to perform their design function for the life of the
facility and post-closure period is best estimated through accelerated test methods described herein.
The study consisted of two separate testing efforts, one aimed at evaluating selected natural clay linings
and the other at evaluating selected geosynthetics.  Both tests were  performed using the same waste.

        Leachate was collected from two sources, one considered modern, and the other considered
older technology.  Site A was a state-of-the-art MWC ash monofill leachate facility. This facility had a
scrubber, and ash disposed of in the monofill contained bottom ash, fly ash, and scrubber residue.  Site
B was an older MWC ash monofill leachate facility. This facility did not have a scrubber.  Ash disposed
of in the monofill contained bottom ash and fly ash.

       The following generic geomembrane types were selected at  random to be tested: high-density
polyethylene (HOPE), reinforced chlorosulfonated polyethylene  (CSPE-R), and polyvinyl chloride (PVC).
One filtration/separation geosynthetic was tested:  a nonwoven polyester geotextile.  Three compacted
soils (Illinois, Lufkin, and Nacogdoches) were evaluated to determine their resistance to the two MWC
ash leachates.

       The chemical resistance of three types of geomembranes and a nonwoven polyester geotextile
with samples of two MWC ash leachates was investigated in accordance with EPA Method 9090 and
associated supplementary guidance by determining whether the analytical and physical properties of
these materials were adversely affected by exposure to the two leachates. Analytical testing was
performed to fingerprint the geomembranes and the  geotextile so that the results of these compatibility
studies could be used for comparison to help assess other geosynthetics that might be potential
candidates for use in constructing lining  systems for MWC ash  monofills. In addition, a series of pouch
tests was performed in which samples of the two leachates were sealed in the pouches prepared from
the three respective geomembranes.

       Part of the study was performed to determine any changes in the hydraulic conductivity of
compacted soils exposed to MWC leachate.  The purpose of this study was to determine if the selected
compacted soils are chemically resistant to MWC ash leachate.  Three compacted soils were evaluated
to determine their resistance to two MWC ash leachates.  Samples of the three soils were compacted to
90 percent of proctor compaction (ASTM D 693) in double-ring permeameters. The compacted soils
were then permeated with water, followed by the MWC ash leachates, to determine the hydraulic
conductivity of the soil.

       The objectives of this study were: 1) to evaluate the hydraulic conductivity changes of MWC ash
leachate on natural clay liners; 2) to provide study results to support requirements for lining MWC ash
disposal facilities;  and 3) to determine if high-salt content of MWC ash leachate will affect the
permeability of natural clay liners; and 4) to determine the chemical resistance of geosynthetic products
to the collected leachates.                    ;
       A Sampling and Analysis Plan (SAP) was developed to establish procedures for obtaining
samples of ash and leachate from two MWC facilities selected for this study. Leachate was collected
from operating MWC facilities and their disposal monofills for use in conducting compatibility testing with
geosynthetic materials, and natural clay liners.

       The results of analyzing the leachate saimples at the end of each exposure period show that the
contents of the cells remained essentially constant throughout the exposures. . ,

Natural Lining Components                                                       ,

       Permeability changes to clay soils upon exposure to the two ash leachates were assessed using
SW 870's Appendix III C method, "Test Method for the Permeability of Compacted Clay Soils." Stainless
steel double-ring permeameters were used to evaluate the compatibility of three compacted soils with
two MWC ash leachates.  Six samples of each of the soils were compacted to 90 percent of standard
proctor compaction (ASTM D 693) in 15-cm permeameter molds.

       The compatibility test involved determination of the hydraulic conductivity of the compacted soil
to a standard leachate (0.005 N CaS04) followed by one of the two MWC ash leachates.  MWC ash
leachates from Sites A and B were used in this study.

       Compacted soil samples were prepared for hydraulic conductivity testing and their bulk density
was estimated.  A double-ring insert, filter, and insert guide were carefully lowered over permeameter
molds until the inserts were firmly seated in the compacted soil samples. The base plate/mold
assemblies were turned over and geotextile filter material was placed over each compacted soil surface.
Water (0.005 N CaSO4 solution) was poured on  each soil sample and a top plate was placed  on each
mold. Air pressure over the water was slowly increased until 3 to 5 psi was attained along with stable
baseline hydraulic conductivities.  The water was then removed from the surface of the soil samples and
replaced with MWC ash leachate.

       The pore volumes of leachate that passed  through the soil samples and the time increments
over which the leachate was collected were recorded for each compartment (inner and outer  rings) of
the double-ring permeameters. The collected data were used to calculate both the total pore volume of
leachate that passed through each soil sample and the hydraulic conductivity of each sample.

       Electrical conductivity (EC) was used as an index parameter to document the breakthrough of
the leachate through the soil samples. Leachate that permeated the soil samples was collected and
divided into two 15-mL aliquots.  EC measurements were made of the saturated paste extract of each
soil type, the water used in the study, and each of the MWC ash leachates.


       Tests were performed on the unexposed and exposed geomembranes.  This testing protocol
conformed to the testing requirements of Method 9090.  U.S. EPA Method 9090, which was specifically
designed to assess the  chemical resistance of geomembranes and waste liquids, is divided into two
parts; the first part deals with the exposure of geomembrane samples to a waste liquid, and the second
part  is concerned with the specific tests  performed on the geomembranes before and after exposure.  In
this test,  slab samples are immersed for  up to 4 months at 23° and 50 °C in a representative sample of
the waste liquid or leachate that would be contained by the geomembrane. Analytical and physical tests
are performed on the unexposed geomembranes for baseline data and on samples exposed to the
waste liquid for 30, 60, 90, and  120 days.

       Current U.S. EPA regulations require that all geosynthetics used in constructing a RCRA
hazardous waste management facility must be tested for chemical resistance with the waste to be
contained. Therefore, the U.S.  EPA has  proposed supplementary guidelines so that geosynthetics other
than geomembranes can be tested in accordance with Method 9090.  This guidance states that all
geosynthetics are to be exposed under the conditions described  in Method 9090.

       The analytical properties and the extractables of the exposed  samples were measured in
duplicate for the unexposed geomembranes, but only single determinations were made of the volatiles
contents. The volatiles and extractables were measured in accordance with Matrecon Test Methods 1
and  2. The tests indicate the type of leachate constituents that may have been absorbed by the
geomembrane (i.e., volatile or nonvolatile constituents) and whether the leachate extracted components
of the geomembrane compound such as plasticizers or antioxidants.

        Integrity changes to geomembranes and a geosynthetic material were tested by  exposing three
geomembranes and one geosynthetic material to the two field-collected ash leachates. Standardized
Method 9090 and current U.S. EPA guidance-specified test conditions were maintained; test criteria for
assessing integrity changes specified in  Method 9090  and U.S. EPA guidance were also  utilized.
 Natural Lining Components

        The passage of more than two pore volumes of MWC ash leachate (from Sites A and B) through
 three compacted soil samples (Illinois, Lufkin, and Nacogdoches) showed no significant changes in
 hydraulic conductivity of these soils.  Because the hydraulic conductivity values of the three soils to both
 MWC ash leachates did not significantly increase over the values to water, the soils were considered to
 be chemically resistant to both MWC  ash leachates used in the study.


        The results of the chemical resistance test of the three geomembranes and the nonwoven
 polyester geotextile at both 23° and 50 °C indicated that, within the 4 months of exposure to the two

 MWC ash leachates, the changes in analytical and physical properties were comparatively small. The
 results for the HOPE geomembrane and the polyester geotextile indicate that neither of these materials
 were affected by the immersion and thus are Considered to be chemically resistant to the two MWC ash
 leachates to which they were exposed. The GSPE-R geomembrane showed essentially no change in
 strength characteristics; however, the analytical properties which relate to the CSPE coatings showed
 slight increases in volatiles and weight and a decrease in extractables. The values of all three of these
 properties were continuing to change at the  end of the 4 months of exposure.  Also, there was a slight
 trend downward in ply adhesion.  During  the 4 months of exposure, the PVC geomembrane  also
 exhibited little change in properties, indicating short-term compatibility.  During the last 2 months of
 exposure, however, the PVC showed a trend that could indicate long-term lack of chemical resistance.
 To determine whether the trend is continuing, testing is underway with results expected in  1992.

        The results for the CSPE-R geomembrane samples in each leachate indicate that the polyester
 fabric reinforcement maintained its strength during the 5 months of exposure and showed  no trends
 toward change. The strength was judged by hydrostatic resistance, puncture resistance, and tensile
 properties.  Thus, like the polyester geotextile, this fabric is considered to be chemically resistant to each
 of the MWC ash leachates.  The CSPE coating showed slight effects of the immersion,  however, and
 slight continuing trends in the analytical properties.  For example, the results of testing the CSPE-R
 geomembrane showed that the geomembrane increased in weight (up to 7.4 percent),  but that this
 Increase resulted predominantly from water absorption.  There were slight decreases in extractables, in
 the case of the slabs immersed at 50°C.  Also, there was a slight decrease in the ply adhesion between
 the two layers of CSPE, which may reflect complete loss of adhesion to the  fabric or some apparent loss
 caused by the stiffening of the CSPE-R as a result of crosslinking.

        In the case of the HOPE geomembrane, there were slight increases  in the values for tensile at
 yield, modulus of elasticity, tear strength,  hydrostatic resistance, and hardness.  These changes may
 probably be attributed to a slight increase in  crystallinity and hardening of the HOPE geomembrane
 during the course of the exposure.  There was! also a trend toward a slight loss in weight during
 exposure, which may be a reflection of the extraction of the antioxidants from the HOPE compound.

        During the 4 months of exposure  to the two leachates, the PVC geomembrane samples showed
 an increase in volatiles contents, a decrease in weight, and signs of a slight loss of plasticizer, especially
 on exposure to the leachate with the higher concentration of salts.  In physical properties, the tensile
 strength tended  to decrease, and the elongation at break tended to increase. In stresses at 100 and 200
 percent elongation, the trends for most of the samples were slightly downward,  except during the last
 2 months, when the trends were upward, as were the puncture and hydrostatic  resistances. The
 hardness changes were small, but generally the trends were downward.


       Tests were conducted on selected natural and synthetic lining components involving exposure to
 specific collected MWC ash monofill leachate. Testing of natural lining components involved
 observations of hydraulic conductivity and electrical conductivity.  Testing of the geosynthetics involved
 U. S. EPA Test Method 9090 with modifications where required. The results of the testing indicate that
with proper engineering considerations, carefully selected materials can be expected to perform as

       These test results indicate a series of tests that are likely to be performed during the permitting
and prior to construction of any waste disposal facility and are to  be considered results specific to the
two leachate samples and  selected barrier components collected for the purposes of this study. No

inferences are to be made regarding the materials or procedures used herein regarding any other
combination of lining materials or waste that is intended to be contained. Site specific testing and
analyses are the only accurate way to determine lining component chemical resistance with the waste to
be contained. The test methods used in this study are currently accepted methods of accelerating long-
term exposure.

       The intention of this study was to determine if existing lining technologies were capable of
serving to contain MWC ash monofills. This study has determined that there are materials that do exist
that proved their potential utility under these accelerated exposure testing scenarios, on two specific
leachates.  Soil, geosyntetic material and leachate quality variations preclude the authors from
extrapolating any chemical resistance issues beyond the components and procedures discussed in the
study and project final report.
Koerner, Robert M., editor.  1990.  "Chemical Resistance Evaluation of Geosynthetics Used In Waste
Management Applications," Geosynthetic Testing for Waste Containment Applications. ASTM STP-1081.
American Society for Testing and Materials, Philadelphia, PA, 1990.

United States Environmental Protection Agency.  1986.  Test Methods for Evaluating Solid Waste. 3rd
Edition.  EPA/SW-846.  Office of Solid Waste and Emergency Response, Washington, DC.

United States Environmental Protection Agency.  1988.  Lining of Waste Containment and Other
Impoundment Facilities. EPA/600/2-88/052 (NTIS PB-89-129670).  Risk Reduction Engineering
Laboratory, Office of Research and Development, Cincinnati, Ohio.

                                  A TWO STAGE PROGRAM

                                       Jerry Isenburg
                                   University of Cincinnati
                                  USEPA Center Hill Facility
                                     5995 Center Hill Rd.
                                   Cincinnati, Ohio 45224

                                     Extended Abstract
       Solidification/Stabilization (S/S) technology uses binders added to hazardous waste such as
contaminated soil to accomplish two goals:

       1. to render the toxic metal in the soil insoluble (stabilize) and

       2. to develop physical strength for handling and disposal (solidify).

The binders contain a net alkalinity which resists leaching by acidic TCLP (EPA SW846, Method 3811)
solutions and also react to form hydraulic binding constituents.  The two goals are not necessarily
synonymous however.  Some solidifiers do not stabilize and some stable systems are soil like or even
slurries.  For disposal in land fills, both properties are desirable. The goal of this project was to collect
data on these properties to support S/S as a Best Demonstrated Available Technology (BOAT) for soils
contaminated by lead. This abstract is a partial summary of the on site engineering report (1).

       This project consisted of two stages.  Both stages are presented here chronologically since they
were not planned together but do depend on each other.  Both stages subjected a soil typical of lead
battery sites to a spectrum of carefully designed S/S recipes.  These recipes used only generic binder
systems. The primary target for the project was to attain TCLP lead concentrations below 5 mg/l, and
a secondary target was a minimum unconfined compressive strength (UCS) of 345 kPa (50 psi).

Site And Soil Characteristics

       The site chosen to supply the waste was a battery breaking site in Pennsylvania.  This choice
was made because the primary contaminant was lead, the site was accessible, and contamination from
organic wastes was a minimum.  Four samples  were taken. Results of an on site survey with a field
x-ray spectrophotometer indicated that two samples would contain over 20,000 ppm  lead and the
other two would contain a little less than 10,000 ppm lead.  The composite was expected to fall in
the range of 15,000 to 20,000 ppm lead. All soil was screened on site to pass a 3/8-inch sieve to
omit battery pieces, and the appearance of the soil was a dark damp silty-clay-peat.

       Analyses of the untreated soil after compositing of the four samples showed the following:

       1. Metals analysis of solids
         Iron           21000 ppm
         Lead          21000 ppm
         Aluminum       6700 ppm
         All others below 1000 ppm

        2. TCLP: elements failing Toxicity Characteristics level
          Lead: 91 mg/l,  limit: 5 mg/l

        3. Total Organic Carbon: 170,000 ppm

        4-. Moisture: 27.7%

        5. pH:   4.3


        We have previously demonstrated a method to design S/S recipes that will pass the TCLP test
 (2). The objective of this method is to create conditions at the end of the TCLP test which minimize
 the solubility of lead. Lead exhibits minimum solubility at about pH 8 to 10. To attain this desired pH
 at the end of the TCLP test, the indigenous alkalinity of contaminated soils needs to be augmented by
 the amount that will neutralize the acid specified by the TCLP plus enough to raise the pH to 8 to 10.
 We have previously developed a laboratory procedure to measure the acid neutralization capacity of
 solids (3). This test has been used to determine the acid neutralization capacity of several binders (4).
 These binder values have been previously used in a procedure to select types and amounts of binders
 for treating a lead contaminated soil at a battery disposal site (5).

        In this project three binder types were selected:

        1. all portland cement- has a dependable chemistry and high alkalinity

        2. 3 parts Type F fly ash to 2 parts  quicklime- minimum weight of alkaline binder

        3. 2 parts cement kiln dust to 1 part Type F fly ash- both waste products having low cost

        The mix design plots of p.H versus acid reactant added allow prediction of one mix design for
 minimum lead in TCLP leachate and another for minimum binder added to pass the TC list limit.  These
 two criteria lead to the following recipes:

  mix #1.16% portland cement- minimum cement level

        2. 20% portland cement- minimum lead in leachate

        3. 8.5% quicklime +  12.75% fly ash- minimum binder

        4. 10.5% quicklime + 15.75% fly ash- minimum lead in leachate

        5. 24% cement kiln dust + 12% fly ash- minimum kiln dust level

        6. 28% cement kiln dust + 14% fly ash- minimum lead in leachate

       These six mixes were prepared in a  standard laboratory mixer with sufficient water to reach
a common flow table consistency. They were cast in cylinders and cured in a 100% relative humidity
chamber for 28 days while set was being monitored by penetrometer on small samples.  Mixes one
and two set hard. Mixes three and four stiffened but did not set completely.  Mixes five and six did
not set by 28 days.  The UCS values for the  six mixes were, in order, 462, 503, 241, 207, 0, 0 kPa.


       The TCLP test were run on the UCS fragments. All the samples failed the TC level of 5 mg/l
of lead. In addition, the pH's at the end of leaching were, in order, 5.26, 6.31, 5.3, 6.12, 5.44, 5.73
where the target pH was 8 to 9.75.        j                           .         ,


       Another EPA project at Center Hill was evaluating the GANC/MANC test. The UCS fragments
from the first phase of this project were tested using the GANC/MANC test (5). The acid neutralization
capacity of the samples cured for the standard 28 days was less than was  predicted from an algebraic
combination of the 24 hour GANC test values for the mix ingredients.  Measurements of the lead
released during the GANC test (MANC) at various pH's showed that the  lead in the leachate would
have been low enough to pass the TC level if the pH had been in the target range of 8 to 1.0.

METHODOLOGY II                                                                 ,
       The original mix calculations were studied in relation to the actual GANC results for the mixes.
For each binder type, there seemed to be a single multiplier that would increase the GANC equivalents
of acidity measured on the waste such that the  prediction equation would give the GANC values
actually demonstrated by the mixes. These factors were used to predict the increase in binder required
to bring the  pH to the desired level.  The essence of this assumption is that the waste is more acid
than the GANG showed it to be in 48 hours of contact. The following three mixes were designed by
increasing the acidity of the  soil by a constant factor and increasing the binder quantities accordingly.
Note that the price of the high organic content was at least a doubling of the binder requirement.

 mix # 7. 45% Portland cement

       8. 31 % quicklime +  46.5% fly ash

       9.  93% cement kiln dust  +  46.5% fly ash                        ...-.,•

       A major change in  acid neutralization  capacity during curing of the sample has not been
observed in previous applications of the GANC test to mix designs. A study of the literature for factors
that could change the acidity of a soil between 2 and 28 days in these conditions led to identification
of possible organic reactions.  Cellulose molecules can be oxidized to acid groups when they are
activated by alkaline exposure. That suggests that the problem is the 17%  total organic carbon tied
up in the soil. To test this hypothesis, one more mix was prepared which removed most of the organic
materials by ashing the soil  at 300°C and then preparation of one of the failed mixes with correction
for the loss in water and organics weight during ashing.  The following mix  was chosen to complete
Phase II of this work:

mix  #10. 20% Portland cement based on weight before ashing- comparable to mix 2.

       The ashing process showed 17% weight loss from ignition excluding  the water loss on drying.
This  is not a complete removal of organics but the structures are probably oxidized enough to show
little  further changes in acidity.

       The mixes all set by 28 days.  The UCS values were, in order, 2612, 197, 178,  1618 kPa.
while the second and third mixes did not achieve the 345 kPa level desired, they did develop sufficient
strength for many disposal situations and can be expected to develop strength over a longer time.than
the cement samples.


       The pH at the end of the TCLP leaching tests was, in order, 11.11, 10.52, 11.65, and 8.90.
All of these would be predicted to pass the TC level of 5 mg/l of teachable lead. The  actual results
from the TCLP were, in order, Below Detection Limit (BDL) of 0.2 , 1.5, 0.51, BDL mg/l. All samples
of Stage II passed the TC level for lead!


       1. S/S is recommended as a BDAT for lead contaminated soil.

       2. Natural peat type organic materials in the soil appear to interfere with the effectiveness of
       the binders. This can increase the binder requirement for effective stabilization to over twice
       the level required in the absence of the organics.

       3. The current GANG test for raw soil is not able to detect the longer time organic reactions
       shown by this soil.

       4. Any of several generic binder systems can be used to achieve TC levels of lead teachability.

       5. Portland cement sets faster and provides the best strength at one month age  when used at
       the level required for stabilization.

       6. These mix design procedures will work reliably if all the acid/base reactions are  detected.

       1. The GANG test should be revised to account for organic acid/base reactions.

       2. Binder selection can be based on alkalinity and cost instead of previous testing only.

       3. Biological reduction of total organic carbon contents should be researched for sites such as
       the Brown's Battery Breaking  site.  Composting is a much more desirable treatment than
       burning to prepare the soil for S/S.


Report 1.  "Onsite Engineering Report For Solidification/Stabilization Treatment Testing Of Contami-
       nated Soils," IT Environmental Programs Inc.,  USEPA Contract No. 68-C9-0036, Manager:
       R. P. Lauch, RREL, in  preparation.

Paper  2. Isenburg, J. E.  and McCandless, R. M.,"Engineering The Solidification/Stabilization Of Heavy
       Metal Contaminated  Wastes," presented  at WASCON Conference, Maastrict, Netherlands,
       November, 1991, publication pending.

Paper   3.  Isenburg, J. E. and Moore, M. R., "Generalized Acid Neutralization Procedure (GANG),"
       Stabilization and  Solidification  of Hazardous, Radioactive, and Mixed Wastes,  2nd Volume,
       ASTM STP  1123, T.M. Gilliam and C. C.  Wiles, Eds.,  American Society  for Testing and
       Materials, Philadelphia, 1992, pp.  361-377.

Report 4. Isenburg,  J. E., "Binder Characterization Study," report in process

Report 5. "Solidification/Stabilization Treatability Assessment Report, Kassouf-Kimmerling Battery
       (KKB) NPL Site," by University of Cincinnati for USEPA  Region IV, Atlanta,  Georgia,
       September 1990.



                                  Ronald J Turner
                         U.S. Environmental  Protection Agency
                       26 West  Martin  Luther King Driye
                         Cincinnati,  Ohio   45268


     The process  of developing treatability information on the RCRA listed
waste, K088 (spent potliner from  the  primary  reduction of aluminum), consisted
of waste characterizations  at  three facilities, selection of the "worst case"
with respect to cyanide  and fluoride, and incineration. These data were made
available to ERA'sOffice  of  Solid  Wastes and the aluminum industry.

    Incineration  was selected  as  an appropriate treatment process as the spent
potliner samples  contained  over 30 percent  fixed carbon, greater than 5000
BTU/lb heat values, and  cyanide is destroyed  by thermal incineration.


    All primary aluminum produced in  the United States is made by the Hall-
Heroult Process.  Aluminum  is  refined by dissolving alumina in a molten
cryolite (NagAlF6) bath and  then  introducing electric  current.  The  reduction
takes place in carbon-lined steel and refractory cells or pots.  The carbon
liner serves as the cathode.   This lining becomes impregnated with the
cryolite and metal over  time and  failures occur.  A service life of 3 to 5
years for a potliner is  common. The upper portions of the carbon lining from
the bottom and side walls is "first cut" and  is classified as K088.   The
"second cut" material  is thermal  insulation and is not K088.  The mechanism by
which cyanide  is  formed  in  the potliner is  not discussed in the literature,
but carbides and  nitrides of aluminum are known to be present in the carbon
lining.  Table 1  presents a summary of the  K088 waste characterizations.
Facility Three was selected for the test burn program.


      The objectives for these tests were to  establish whether the potliner
could be incinerated and to characterize the  residuals.  The rotary kiln
incineration system at the  Incineration Research Facility,  Jefferson, AK.
was employed for  the tests.   Cyanide was considered as the principal organic
hazardous constituent  (POHC),  and is the primary constituent of concern.
Three tests were  conducted  under essentially  the same operating conditions,
except for exit temperatures.  The planned  incinerator operation conditions
are summarized in  Table 2.   These conditions  were chosen to maximize the
carbon burn out.  The actual kiln operating conditions achieved for each test
are summarized in Table 3.          f


      Three composite waste feed samples and two composite kiln ash samples
were collected.  One set of flue gas: analyses  was completed each test day.  The

scrubber system was operated at total recycle for the three test days, and one
composite scrubber liquor sample was collected.  Table 4 summarizes the
proximate and silica analysis results.  Approximately half of the original
carbon content was oxidized during the incineration test.  About 80 percent of
the ash content was discharged as kiln ash; the remainder was either
volatilized or entrained as particulate in the flue gas.

      Table 5 summarizes the cyanide concentrations for all samples analyzed.
The first test samples contained an average of 5,200 mg/kg total cyanide.  The
waste fed during the second and third days contained less cyanide, or about
3,500 mg/kg.  Kiln ash cyanide content varied from test to test, and from
sample to sample within a test day.  Measured levels were in the range of 60
to 330 mg/kg.  Kiln ash leachates contained estimated cyanide levels, ranging
from 0.5 to 0.6 mg/L for the Test 1 ash, and 3 to 4 mg/L for Test 2 and 3 ash.
No cyanide was detected in the scrubber liquor or scrubber exit flue gas

    The cyanide destruction/removal efficiency (ORE) data are given in Table
6.  The DREs were better than 99.9999 percent at both the scrubber exit and at
the stack for Test 1, and 99.99987 for Tests 2 and 3.  The fraction of cyanide
remaining in the kiln ash was calculated to be 2.7 percent of the feed, so
97.3 percent was removed by the incineration process.

Kiln ash fluoride levels were comparable to the waste levels (1.3 to 6.8
percent).  The leachate levels were generally less than 100 mg/L (one sample
result was 668 mg/L fluoride).  The kiln ash contained about 64 percent of the
waste feed fluoride.


      The kiln ash contained measurable cyanide and carbon burn out was not
complete.  The K088 material formed slag at temperatures above  1800 degrees F.
This was in contrast to the results of the preliminary ash fusion tests which
indicated a 2700 degree F fusion temperature.  About 20 percent of the kiln
ash collected was slag removed from the kiln after completion of the tests.
About a 30 percent reduction in waste weight occurred with this incineration
test.  Tests will be conducted to determine whether the fluoride in the kiln
ash requires further treatment to restrict its Teachability.

Whitworth, W.E., Lee, J.W., Waterland, L.R. Pilot-Scale Incineration Tests of
Spent Potliners from the Primary Reduction of Aluminum (K088).  U.S.
Environmental Protection Agency, Cincinnati, Ohio

Cadmi urn
Percent Moisture
Percent Ash
Percent Volatile
Percent Fixed Carbon
Ash Fusion Temp (°F)
Facility 1
145 i
8.7 1
Facility 2
Facility 3
5394 '
                          TABLE 2. TARGET TEST CONDITIONS
          Total waste feedrate
          Kiln temperature
          Kiln exit flue gas 02
          Afterburner temperature j
          Afterburner exit flue gaj> 02
          Scrubber blowdown flowrate
          Scrubber liquor flowrate|
          Scrubber pressure drop
          Scrubber liquor pH
                68 kg/hr (150 Ib/hr)
                980 °C(1,800°F) ,
                10  percent
                7  percent
                0  L/min (total  recycle)
                230 L/min  (60 gpm)
                1.5 kPa (6  in WC)
                7.5 to 8.0
                      TABLE 3. KILN OPERATING CONDITIONS
  Test 1
  Test 2
  Test 3
  Average natural gas feedrate
  scm/hr                        49!
  (scfh)                        (H720)
  kW                            504
  (kBtu/hr)                     (H720)

Test 1 Test 2
(1/15/91) (1/16/91)
Test 3
Average combustion air flowrate
scm/hr 408 410 395
(scfh) (14,400) (14,470) (13,950)
Average total air flowrate
scm/hr 1,297 1,320 1,249
(scfh) (45,790) (46,610) 44,090)
Average kiln draft
Pa 12 15 15
(in WC) (0.05) (0.06) (0.06)
Exit temperature
Range, °C 962-1,062 954-1016 922-1012
Range, (F) (1,764-1,944) (1,7649-1,861) (1,692-1,853)
Average, °C 999 984 972
Average, (°F) (1,830) (1,803) (1,781)
Exit 02
Range, % 9.6-12.3 9.9-12.8 9.7-11.4
Average, % 11.0 11.6 11.4
Average waste feedrate
kg/hr 66.4 62.2 66.8
(Ib/hr) (146) (137) (147)
Concentration, wt %
Samp! e
Test 1 (1/15/91):
Waste la
Kiln ash la
Waste Ib
Kiln ash Ib
Waste Ic
Test 2 (1/16/91):
Waste 2a
Kiln ash 2a
Waste 2b
Kiln ash 2b
Waste 2c
Test 3 (1/17/91):
Waste 3a
Kiln ash 3a
Waste 3b
Kiln ash 3b
Waste 3c






Total Fixed
plus volatile



Moisture Ash Silica










                       TABLE 5.  CYANIDE ANALYSIS RESULTS
Test 1 (1/15/91):
Waste la, mg/kg
Kiln ash la, mg/kg
Kiln ash la TCJ.P leachate, mg/L
Scrubber liquor filtrate la, mg/1
Scrubber liquor solids la, mg/kg
Waste Ib, mg/kg
Kiln ash Ib, mg/kg
Kiln ash TCLP leachate, mg/L
Scrubber liquor filtrate Ib, mg/L
Scrubber liquor solids Ib, mg/kg;
Waste Ic, mg/kg
Scrubber exit flue gas, /tg/dscm
Stack gas, /ig/dscm
Test 2 (1/16/91):
Waste 2a, mg/kg
Kiln ash 2a, mg/kg i
Kiln ash 2a,TCLP leachate, mg/L
Scrubber liquor filtrate 2a, mg/L
Scrubber liquor solids 2a, mg/kg
Waste 2b, mg/kg
Kiln ash 2b, mg/kg
Kiln ash 2b TCLP leachate, mg/L ;
Scrubber liquor filtrate 2b, mg/L
Scrubber liquor solids 2b, mg/dscm
Waste 2c, mg/kg
Scrubber exit flue gas, /ig/dscm i
Stack gas /ig/kg ;
Test 3 (1/17/91):
Waste 3a, mg/kg
Kiln ash 3a, mg/kg
Kiln ash 3a TCLP leachate, mg/L
Scrubber liquor filtrate 3a, mg/L
Scrubber liquor solids 3a, mg/kg
Waste 3b, mg/kg
Kiln ash 3b, mg/kg
Kiln ash 3b TCLP leachate, mg/L
Scrubber liquor filtrate, mg/L
Scrubber liquor solids 3b, mg/kg
Waste 3c, mg/kg
Scrubber exit flue gas, /ig/dscm
Stack gas, /ig/dscm
Total CN



Amenable Fraction
CN amenable, %



, NA
2,900 '










"NA « Not analyzed.
If total  CN not detected,  amenable CN analysis'not

                             TABLE 6 CYANIDE DREs
  Test 1
   lest z
   lest 3
Waste Feed:
  Waste feedrate, kg/hr               72              68           72
  Average CN concentration, mg/kg     5,240           3,4QO        3,560
  CN feedrate, g/hr                   377             231    .      256
Scrubber exit flue gas:
  CN concentration, /zg/dscm           <0.16           <0.15        <0.16
  Flue gas flowrate, dscm/min         29.5            34.6         35.2
  Flue gas CN emission rate, /fg/hr    <280            <310         <340
  CN ORE, %                           >99.99993       >99.99987    >99.99987
Stack gas:
  CN concentration, /zg/dscm           <0.14           <0.14        <0.15
  Flue gas flowrate, dscm/min         33.0     ,       35.5         36.6
  Flue gas CN emission rate, #g/hr    <280            <300         <330
  CN DRE,%                            >99.99993       >99.99987    >99.99987


                      David Dahnke, Dale Flynn, Scott Shuey and Larry Twidwell
Department of Metallurgical and Mineral Processing Engineering
     Montana College of Mineral Science and Technology
                   Butte, Montana  59701
                      (406) 496 4208

        An extremely large data base has been generated at Montana Tech for the treatment of a wide
 variety of sludge materials.  Emphasis has been given to the treatment of electroplating and
 electromachining sludge materials.  These investigations have shown that a series of hyclrometallurgical
 unit operations can be performed to selectively recover all metal values from the hydroxide waste
 materials.  Four publications (1-4) and ten master of science theses (5-14) have been completed that are
 directly related to this project, e.g., the theses include the following: Laney  has investigated the
 effectiveness of leaching electroplating and electromachining sludge materials in sulfuric acid and the
 use of solvent extraction reagents to recover copper and zinc from the produced multicomponent sludge
 leach solutions (5); Dahnke  has summarized research on zinc and iron solvent extraction, and his work
 produced the initial data upon which the phosphate process is based  (6); Arthur investigated the
 application of the phosphate process to chloride-bearing sludge leach solutions (7); Konda investigated
 Iron-zinc separations from high zinc solution in a sulfate solvent matrix (8);  McGrath studied the
 speclation of chromium in phosphate-bearing solutions and  the kinetics of chromium phosphate
 precipitation (9); Rapkoch studied the phosphate precipitation of trivalent cations from the
 ammonia/ammonium sulfate system (10); Nordwick conducted studies on the rate of conversion of ferric
 phosphate to ferric hydroxide (11); Quinn investigated the conversion  of chromium  phosphate to other
 more marketable products by soda ash fusion (12); Flynn investigated the use of cyanide complexation
 for separation of nickel from cobalt (13); and Shuey (14) is presently investigating refinements on the
 cyanide process for selectively separating nickel from cobalt and subsequently recoveririq the cobalt in a
 high purity form.

        Because of the problem of summarizing and representing such a large amount of data in the
 brief space available, the approach used in this presentation is to summarize the results and conclusions
 without including a great deal of detail concerning the separation process.   The authors are, therefore,
 relying on the reader to solicit copies of individual theses and publications of interest.  The emphasis in
 this presentation will be placed on the treatment of electrochemical machining sludges; especially on the
 selective separation of nickel from cobalt. Also, research that is presently in progress will be reported
 and discussed in the oral presentation, i.e., methods studied to recover high purity cobalt from nickel
 depleted cyanide solutions.

                                          ECM Sludges

        Electrochemical machining (ECM) sludge materials are produced as a result of electrolyte
 solution treatment. During the ECM  process, the work piece is dissolved into the electrolyte by an
 electrochemical depleting reaction. Because the efficiency and control of the ECM process is  partly
 dependent on the chemistry of the electrolyte solution, simple water treatment technologies are used to
 control the concentration of dissolved metals in'the electrolyte.  A highly oxidized Heavy metal hydroxide
 sludge results from the electrolyte treatment operations. After filtration, the sludge materials are
 generally supplied as a feed  material to a pyrometallurgical operation or are disposed of in  hazardous
waste sites. The waste material contains appreciable metal values.


        Phosphate precipitation has been investigated and demonstrated to be  successful for selectively
separating trivalent cations from divalent cations in complex mixed  metal leach solutions produced from
electroplating sludge materials by Twidwell, Dahnke, and others (1-4).  These investigators, have also
shown that trfvatent chromium can be effectively separated from trivalent iron in the  presence of divalent
nickel and cobalt (4). The flowsheet for the phosphate process is presented in Figure 1.

       The application of phosphate precipitation technology also has been shown to be appropriate
for treating ECM sludge leach solutions for the removal of iron and the recovery of chromium (2).
However, the separation of divalent cations such as nickel and cobalt one from the other requires an
approach other than phosphate precipitation. Figure 2 shows the unit operation sequence for the
treatment of ECM hydroxide sludge materials using cyanide complexation, nickelic hydroxide
precipitation, and cobalt recovery by acid  baking, redissolution and electrowinning.
 TO NON- *—I / L,


           TO NI/Co SEPARATION

                                                          NlgO 3 PRODUCT
 Figure 1.  Metal value recovery from electroplating
 and electromachining sludges.
                          Figure 2. Selective separation of nickel and
                          cobalt by cyanide complexation.
        The nickel-cobalt starting materials were prepared by treating ECM sludge by the flowsheet (2)
 presented in Figure 1, e.g., the sludge was leached in sulfuric acid, filtered, iron was precipitated and
 filtered as ferric phosphate, chromium was precipitated and filtered as chromium phosphate, and
 nickel/cobalt was precipitated and filtered as hydroxides.  The starting ECM sludge material was
 supplied by Lehr Corporation and its composition is presented in Table 1. The resulting nickel/cobalt
 hydroxide material composition is presented in Table 2.

        The nickel/cobalt material was treated as depicted in the flowsheet presented in Figure 2.
 Bench scale tests were conducted in one-liter reaction vessels and large  scale tests were conducted  in
 twenty liter batches. Solution pH, Eh, and temperature were monitored throughout each test.  Solutions
 and solids were sampled periodically during each test to establish the influence of time on the test
 results.  Solids were examined by both x-ray diffraction and scanning electron microscopy/energy
 dispersive (SEM/EDX) analysis. Solid compositions were determined by digestion and induction
 coupled plasma (ICP) analysis.  Solutions were analyzed by ICP procedures.

   Solids Composition, %
                Fe    Cr   Ni    Co   Nb   Ti   Mo  Al   Ca   Na
 LehrCorp.    11.34 4.88 14.88 3.97 0.78 p.28  1.5  0.03  0.68  11.20

 Starting Material Solid Content: 35.27%

Solids Composition, %
Lehr #2, Wet
Lehr #3, Wet
Lehr #4, Wet

   precipitate containing a nickel/cobalt ratio of 692/1 and a cobalt solution free (within detection limits)
   of nickel within ten minutes.

•  The influence of the amount of added cyanide on the purity of the nickelic hydroxide precipitate and
   cobalt bearing leach solution was evaluated for the following conditions: five gpl nickel, 1.25 gpl
   cobalt, pH 14, one hour residence time, and amount/rate of hypochlorite as above.  The
   stoichiometric requirement for cyanide (for complete complexation) is eight moles of cyanide per
   mole of nickel plus cobalt. Any cyanide above this amount would have to be oxidized prior to the
   oxidation of the nickelo-tetracyano complexes thus requiring the expense of additional oxidant.
   Therefore, the smallest addition of cyanide that produces acceptable products should be used.  The
   following stoichiometric amounts were experimentally investigated: 0.5, 0.75, 1.0, 1.5.

   The influence of the stoichiometric amount of cyanide is not important with respect to effective
   removal of nickel from the solution phase but is very important with  respect to the purity of the
   nickelic hydroxide solid. A deficiency of cyanide in solution significantly increases the level of cobalt
   contamination in the nickelic hydroxide precipitate. Therefore, an excess above the stoichiometric
   amount is required to maintain a high purity solid product.  The nickel/cobalt and cobalt/nickel  ratios
   in the solid phase and in the solution phase were (at 1.5 times the stoichiometric requirement) 690/1
   and 186/1, respectively.

•  The influence of the amount of added oxidant on the purity of the nickelic hydroxide precipitate and
   cobalt bearing leach solution was evaluated for the following conditions: five gpl nickel, 1.25 gpl
   cobalt, pH 14, one hour residence time, and 1.5 times the stoichiometric requirement of cyanide. The
   following hypochlorite (5.25%) amounts were investigated: addition (at a rate of 10 ml/minute) of 25
   ml (13.125 gpl), 50 ml (26.250 gpl), 75 ml (39.375 gpl), and 100 ml (52.500 gpl) per 100 ml of starting

   The influence of the amount of oxidant is  not important with respect to the purity of the precipitated
   nickelic hydroxide but is important with respect to the effective removal of nickel from the solution
   phase.  Greater than 75 ml of oxidant were  required for effective nickel removal from solution. The
   nickel/cobalt ratio in the solid phase for this condition was 591/1 and the solution nickel content was
   below the ICP detection limit (therefore, the cobalt/nickel ratio in the solution was greater than

                                  Cobalt Recovery by Acid Baking

        A survey of techniques to recover cobalt from the cobalt hexa-cyano complex was conducted
by Flynn (13). The techniques experimentally investigated included: direct electrowinning cobalt from
solution, acid baking/electrowinning of cobalt metal, and high temperature fusion.  The only treatment
technique shown to be feasible was acid baking/electrowinning.

        Preliminary test work was conducted to establish reagent requirements.  Evaporation  of one liter
of cobalt solution resulted in the formation of 194 grams of solid product. The off-gases were collected,
scrubbed and analyzed for cyanide during the bake operation. No cyanide was detected.  This is in
agreement with literature statements that no  undecomposed cyanide is produced during the
decomposition process.  X-ray diffraction analysis of the acid bake product confirmed that the product
was cobalt sulfate and other sodium, chlorine,  and sulfate compounds.  The cobalt concentration in the
product was approximately three percent.

        Sufficient quantity of this residue was produced to investigate electrowinning.  The solid was
dissolved in sufficient water to produce a solution containing 20 gpl cobalt (pH 5.9).  This solution was
placed in a small electrowinning cell using titanium anodes and lead cathodes with surface areas of 0.25
drrr. At a current density of 1.5 amperes and 6.5 volts, a deposit of 99+% cobalt metal was produced in
five hours.

        Other test work presently underway  includes: destruction of the nickel cyanide complex by
hydrogen peroxide with subsequent recovery of the cobalt by electrowinning; and recovery of the cobalt
by precipitation as a cobalt naphthate solid (a  marketable product).


        Experimental test work has shown that nickel and cobalt can be effectively separated and
 recovered in the form of marketable products from mixed metal hydroxide electrochemical machining
 sludge materials by first producing a mixed nickel/cobalt hydroxide material.  The nickel/cobalt
 hydroxide materials can be redissolved in a calistic cyanide solution.  Nickelic hydroxide can be
 selectively and effectively precipitated from the solution by a dilute hypochlorite solution. The resulting
 cobalt bearing solution can be reacted by acid baking/electrowinning to recover metallic cobalt.


     Twidwell, LG. and Dahnke, D.R. Metal Value Recovery from Metal Hydroxide Sludqes:  Removal of
     Iron and Recovery of Chromium.  NTIS PB-88176078. Cincinnati, OH.  Dec. 1987.  *

     Twiawell, LG. and Dahnke, D.R. Metal Value Recovery from Alloy Chemical Milling Waste:  Phase
     II.  EPA Contract No. 68-02-4432.  Dec., 1987.

 3.   Twidwell, LG., Dahnke, D.R., and McGratH, S.F.  Detoxification of and Metal Value Recovery from
     Metal Finishing Sludge Materials, jn:  H. Freeman (ed.), Innovative Haz. Waste Treatment
     Technology Series,  Physical Chemical Processes. Vol. 2, Chapter 2.6.  1990.  pp 515-61.

     Dahnke, D.R., Twidwell, LG. and Robins, R.G. Selective Iron Removal from Process Solutions by
     Phosphate Precipitation. Jn: J.E. Dutrizac and A. J. Monhemius (ed.), Iron Control in
     Hydrometallurgy, Ellis Horwood, Publisher; Chapter 23.  1986.  pp 477-503.

     Laney, D.G. The Application of  Solvent Extraction to Complex Metal-Bearing Solutions.  M.S.
     Thesis. Montana College of Mineral Science and Technology,  Butte, MT.  1984. 140 pp.

     Dahnke, D.R.  Removal of Iron from Acidic Aqueous Solutions.  M.S. Thesis.  Montana College of
     Mineral Science and Technology, Butte, MT.  1985.

 7.   Arthur, B. Treatment of Iron, Chromium, and  Nickel Aqueous Chloride Acidic Solutions by
     Phosphate Precipitation.  M.S. Thesis. Montana College of Mineral Science and Technology, Butte
     MT.  May 1987.

 8.   Konda, E.  Study of Ferric Phosphate Precipitation as a  Means of Iron Removal from Zinc Bearing
     Acidic Aqueous Solutions. M.S. Thesis.  Montana College of Mineral Science and Technology,
     Butte, MT. May 1986.                              »                               ay,

 9.   McGrath, S. Rate of Chromium  Precipitation from Phosphate Solutions.  M.S. Thesis.  Montana
     College of Mineral Science and Technology, Butte, MT.  May 1992.

 10.  Rapkoch, J. Effects of Substituting Ammonium Hydroxide for Sodium Hydroxide on Metal
     Phosphate Solubilities in Complex Metal Bearing Solutions.  M.S. Thesis.  Montana College of
     Mineral Science and Technology, Butte, Mf. May 1988.

 11.  Nordwick, S. Conversion of Ferric Phosphate Dehydrate to Ferric Hydroxide.  M.S. Thesis.
     Montana College of Mineral Science and Technology, Butte, MT.  May 1987.

 12, Quinn, J.  Conversion of Chromium Phosphate by Sodium Carbonate Fusion. M.S. Thesis. Montana
    College of Mineral Science and Technology, Butte, MT.  May 1988.

13. Rynn,  D.R. Recovery of Nickel and Cobalt from Electromachining Process Solutions.  M.S. Thesis.
    Montana College of Mineral Science and Technology, Butte, MT. May 1990.
14. Shuey, S., New Techniques for Separating  Nickel from Cobalt.  M.S. Thesis, Montana College of
    Mineral Science and Technology, May 1992.

                      U.S. EPA Symposium Presentation

  Treatment of Dilute Hazardous Waste Streams by Sorption/Anaerobic StabUization
                            Margaret J. Kupferle*
                               Tsaichu Chen
                             Vicente J. Gallardo
                             David E. Lindberg
                               Paul L. Bishop

                           University of Cincinnati
               Department of Civil and Environmental Engineering
                         Cincinnati, Ohio 45221-0071

                              DolloffF. Bishop
                             Steven I. Safferman

                     U.S. Environmental Protection Agency
                    Risk Reduction Engineering Laboratory
                        26 W. Martin Luther King Drive
                           Cincinnati, Ohio 45268

     Many wastewater streams contain dilute concentrations of organic pollutants that

are not treated effectively by conventional activated sludge processes. These

pollutants, however, can often be treated effectively anaerobically.  If the pollutants

were treated anaerobically, pass-through of the pollutants to the receiving stream and

stripping of volatile compounds during aeration could be minimized. To treat the entire

wastewater stream in an anaerobic digester would not be economical. However, if the

bulk liquid stream could first be passed through a sorbent bed such as granular

activated carbon (GAC) prior to aeration, only the sorbent material, a much smaller

volume, would require anaerobic stabilization at elevated temperatures.

* Presenter

      Feasibility studies have been completed for a system employing GAC coated with

 anaerobic biomass as the sorbent material. Two 87 L/day bench-scale systems were

 operated for 331 days, one treating unspiked primary effluent and one treating primary

 effluent spiked with 5% landfill leachate and fourteen hazardous organic compounds

 (Table 1). Each system had two stages (Figures 1 and 2). The first stage was operated

 as a sorption unit, and the second stage was operated as a stabilization unit. The

 sorption stage was operated at a two-day carbon retention time (CRT) and an empty

 bed contact time of 30 minutes.  The target CRT in the stabilization stage was 15 days;

 the hydraulic retention tune in this stage approached infinity because the supernatant

 associated with the GAC exchanges was separated from the GAC and returned to the


     In order to establish system capacity for removal of the spiked organic

 compounds, grab samples of the sorption stage influent and effluent were collected for

 GC/MS analysis of volatiles (EPA Method 1624B) and semivolatiles (EPA Method

 1625B) two tunes every three weeks. Grab samples of the off-gases were tested for

 spiked volatile compounds several times during the course of the study using gas

 chromatography with a PID/Hall detector. Sorption stage influent and effluent samples

 for monitoring total and soluble chemical oxygen demand removals initially were

 collected as daily grab samples and later as two-day composites.  Samples for

monitoring sulfate reduction and for assessing the impact of the sorption stage on other

wastewater characteristics important to the downstream aerobic process, e.g., total
suspended solids, nitrogen forms and total phophorus were collected and analyzed

according to EPA methods. In addition, pH, bicarbonate alkalinity, volatile acids, gas

production and composition, temperature, GAC bed volume, and influent, spike and

recirculation flowrates were routinely monitored throughout operation of the

experimental systems.

     Background concentrations of the selected organics in the primary effluent and

landfill leachate used as feed stock for the study varied substantially with time; the

chemical oxygen demand (COD) also varied substantially. The variability is related to

the diverse industrial contributions and combined sewer stormwater flows received by

the Mill Creek Plant, the source of primary effluent in the study. The variability of the

concentrations of the organics and COD entering the sorption stage of the process

provided a real world test of the process on low strength but complex wastewater.

     The spiked organic compound removal data for the year-long study are

summarized in Table 1. Average removals were the highest for the aromatic

compounds. Five of the sk aromatics added were removed at over 95% and the sixth,

phenol, had an 85% removal. Removals of chlorinated aliphatic compound ranged

from 50% for methylene chloride to 95% for trichloroethylene. Removals of phthalate

compounds were approximately 60%.  Removals of ketones ranged from 24% for

acetone to 93% for methyl isobutyl ketone. Analytical interferences due to the

ubiquitous presence of methylene chloride in the analytical laboratory may have

contributed to the low removals of methylene chloride. The spiked organics that

substantially passed through the process (acetone and the phthalates)  are readily

removed by subsequent efficient aerobic treatment.

      The data for the wastewater characteristics of the sorption stage influent and

 effluent samples are sumarized in Table 2 for both the unspiked and spiked systems.

 Average COD removals in both the unspiked and spiked systems consistently

 remained at 40-50% throughout the year-long study. The resulting reduced COD

 loading to the aeration process would substantially reduce air requirements and waste

 aerobic biomass (such as waste activated sludge) in subsequent aerobic treatment.

 Sulfate reduction in the range of 15% was observed in the two systems.  Total and

 volatile suspended solids (TSS and VSS) removals in the range of 20-25% and 4-7%

 were observed in the unspiked and spiked systems, respectively.  The difference in

 removal efficiency may be related to the presence of methanogenic activity in the

 sorption stage of the spiked system. Even at the short hydraulic retention time used in

 the sorption stage, methanogenic activity was noted in the spiked system; it was not

 observed in the unspiked system. Methanogenic activity in the spiked system was

 stimulated by the readily-degradable substrate, methanol, which was used as a carrier

 for the spike. The other parameters, i.e., nitrogen species and total phophorus, were
 not significantly affected by the presence of the sorption stage.

     This feasibility study, performed at bench-scale with complex real-world wastes,

 demonstrated that the experimental system was capable of consistently removing

40-50% of the influent COD for a year-long period. No GAC replacement was

necessary during this time. The reduction of COD discharged to the aeration basin

would reduce aeration requirements as well as aerobic sludge production in actual

application.  In addition, the stabilization process produces methane from the removed

COD which potentially would be recoverable as fuel for heating the reactor. When

hazardous compounds are present in the influent waste, the sorption stage is capable

of trapping significant amounts, preventing their pass-through to the aeration basin and

subsequent volatilization of the strippable chemicals. The sorption stage also

attenuates the effects of shock loads of compounds which may be toxic to the aerobic

portion of the plant. In addition, the combined sorption/anaerobic stabilization stage

retention time for GAC, and, therefore, biomass and sorbed organics, is extremely high,

maximizing the potential for degradation of compounds which are normally recalcitrant

at conventional treatment plant retention times.

            Recycle pump
Syringe pump
                             Feed pump
                       Feed Drum
       Figure 1. Sorption Stage of the Experimental
                   Bench-Scale System

Sight tube
  port for
        pump for —
     of supernatant
                                            Flexible sleeve
                                             coupling for
                                              ready for
   Figure 2. Stabilization Stage of the Experimental
                 Bench-Scale System

TABLE 1.  Spiked Compound Removals in the Sorption Stage of the Spiked System
Mean §D*
Methyl Ethyl Ketone1
Methyl Isobutyl Ketone*
Methylene Chloride3
Bis(2-Ethylhexyl)phthalate 4


Mean SD



  * SD » Standard Deviation
  L Ketone  2 Aromatic  3 Chlorinated aliphatic  4 Phthalate

TABLE 2.  Wastewater Characteristics Data Summary for Sorption Stage
Total COD**
Soluble COD**
NO3-N #
NO2-N #
Total P #
Influent Effluent Percent
mg/L mg/L Removal
Mean SD* Mean SD
* SD = Standard Deviation

Influent Effluent Percent
mg/L mg/L Removal
Mean SD Mean SD

                     VOLATILE ORGANIC COMPOUNDS (VOCs)
     Rakesh Govind, Vivek Utgikar, Y. Shan, Wang Zhao, Department of Chemical
     Engineering, University of Cincinnati,  Cincinnati, OH 45221 (513) 556-2666
     Gregory D. Sayles, Dolloff F. Bishop, Steven I. Safferman, U.S. EPA,, RREL,
                       Cincinnati, OH 45268 (513) 569-7629


       In recent years, the emission into the atmosphere of volatile organic
compounds (VOCs) has undergone increased regulation by EPA, OSHA and other
government agencies due to potential  human health hazards.  The sources of these
VOCs include releases during industrial production  arid use, from contaminated
wastewaters in collection systems and  treatment plants, and from hazardous wastes in
landfills and contaminated ground water.

       Conventional  methods for treating VOC emissions include adsorption on solids.
absorption in solvents, incineration and catalytic oxidation. One alternative  to these
conventional treatment methods is the biological destruction of the VOCs On gas phase
biofilters.  This method has the advantage of pollution destruction (as compared to
transfer to another medium) at lower operation and maintenance costs. The biofilter
method also can be combined with various stripping or vapor extraction separation
processes which effectively transfer VOGs from liquid or solid matrices into the gas
phase  entering biofilters.

       Many immobilized-cell reactors contain films of biomass growing on some type
of adsorbent particle. They include trickling filters used for wastewater treatment,
packed beds proposed for ethanol production, and several fluidized  bed designs for
anaerobic fermentations and aerobic and anaerobic wastewater treatment. Fluidized
beds of floe particles, such as tower fermenters and sludge-blanket reactors can also
be considered immobilized cell reactors because they represent the limiting  case as
the size of the support particle goes to zero.

       Immobilized cell reactors provide several advantages, the principal differences
being superior mass transfer at  higher cell densities, no washout problems, and
capability to operate  in a  continuous fashion.

       However immobilized cell  reactors share the common problem of mass transfer
resistance  associated with the biomass film, i.e., the substrate must diffuse in and
product must diffuse out.  This creates a region of low substrate and high product
concentration on the  inside surface of the biofilm, thereby severely inhibiting
metabolic activity. This requires that biofilm thickness should be minimized to prevent
diffusional  limitations from occuring in the process.

       Furthermore, for packed bed designs, growth of  biomass causes plugging of
the bed, causing high pressure drop  problems in the operation.  The growth of
biomass is especially rapid in aerobic systems.  Hence,  control of biofilm thickness is
an important part of  immobilized-cell reactor design.

      Traditionally, the term 'biofilter* has been used to define  processes that use
compost, peat, bark, soil,  or mixtures of these substances as the filter medium.   These
media serve as a support system for a microbial population. Filter media is underlain

with a gas distribution system, commonly perforated pipe. Gases flow through the bed
where the pollutants are adsorbed to the filter media.  After contact with the
microorganisms the pollutants are broken dqwn thus regenerating the adsorption
capacity of the bed.  Water is sprayed over the bed's surface or by humidifying the
influent gases. The terms "soil filters",  "soil biofilters", or "soil beds" delineate
processes where the filter media is soil. Soil biofilters are generally less permeable to
gas flow than biofliters that use compost, peat, or bark media thus a larger soil biofilter
area is required for the same back pressure.

      Biofilters and soil filters have been applied to control odors from wastewater
treatment plants and  industrial processes since 1953  (1). Recently, these processes
have been used for volatile organic compound emisssions removal from chemical and
process  industries (2,3,4).  Other processes mentioned in the literature that employ
biological treatment of waste gases include bioscrubbers and tricking filters (4,5).

      Recently, experimental data has been obtained on a packed bed biofilter for the
biodegradation of  methylene chloride, trichioroethylene,  and toluene (6,7).  Complete
removal  of these compounds from air was demonstrated using the packed bed biofilter
      This paper reports on the experimental study of the biodagradation of volatile
organic compounds present in the landfill leachates in a novel aerobic biofilter. The
most abundant compounds in  leachate streams were targeted for study. A stripping
study was carried out on the selected compounds to confirm Henry's law constant

      The predominant VOCs from a landfill leachate stream were treated  in a bench
scale biofilter. The following five chemicals (substrates) were targeted for this  study at
the following feed concentrations: Toluene: 450 ppm; Methylene Chloride: 150 ppm;
Trichioroethylene:  25 ppm, Chlorobenzene: 40 ppm, and Ethyl benzene:  20 ppm. The
compounds were fed in vapor form to the biofilter in air.  The required composition of
the compounds in the gas phase was achieved by making the synthetic gas mixtures  in
a cylinder and blending with air. This was done to ensure a uniform feed concentration
to the biofilter. Nutrient solution was circulated countercurrent to the gas through the
bed. The inlet and outlet gas streams were analyzed for the above five  chemicals using
a gas chromatograph (EPA standard method 602).

      The biomass acclimated to  the above compounds was obtained in the following
manner: Biomass from a pilot scale activated sludge plant treating hazardous waste
was suspended in the bioreactor (column 100 mm dia., 700 mm height). The bioreactor'
was fed daily With the five compounds. Nutrients necessary for biomass growth were
added periodically. The biomass from the bioreactor was transferred to the biofilter by
circulating the bioreactor suspension through the biofilter. It was found that the
biomass could be effectively transferred from the bioreactor to the support media in
the biofilter.

      The novel biofilter, developed through our research, consists of a square cross-
section (100 mm x 100 mm) extruded ceramic monolith structure (celite, Manville
Corporation, CA), with 99 square straight passages (6 mm x 6 mm). The biomass

exists as a uniform film immobilized on the inner surface of each straight passage.  The
biofilm is attached to the support material and enables simultaneous diffusion and
degradation of the organics.

      The  major differences between the novel biofilter and the other immobilized cell
bioreactors are as follows:

1.    The  immobilized cell biofilter contains straight passages for the flow of
      gas/liquid phase, thereby providing liquid phase shear, to maintain a. thin biofilm
      on the support structure.  This is distinctly different from a packed bed
      containing support particles, wherein the excessive biomass that shears off the
      particles becomes lodged in the interstitial spaces between the packed
      particles, and cannot leave the bed easily.  In the biofilter, the straight
      passages enable the excessive biomass growth to leave the biofilter due to the
      shear forces exerted by the flow of liquid through the straight passages.

2.    The  straight passages for gas flow also minimizes the pressure drop in the
      biofilter.  In the case of expanded packed beds, or fluidized beds, for typical
      adsorbents, such as activated carbon,  there is significant liquid pressure
      needed to expand the packed bed of particles or fluidize them. Minimizing the
      pressure drop also minimizes the pumping cost for the gas phase, which
      constitutes the major operating  cost for the biofilter process.

3.    Stratification of the microorganisms in the biofilter occurs for a gas stream
      containing mixed substrates.  In mixed substrate systems, the biomass culture
      immobilized in the biofilter at different heights gets naturally adapted to
      different organics, depending on their  biodegradation kinetics.  This
      stratification of the culture, not present in well-mixed systems, is a distinctive
      feature of plug-flow  type  bioreactors.
      Removal efficiency of the biofilter for a compound was defined as the amount of
compound removed from the gas phase;expressed as a percentage of the amount of
that compound fed to the biofilter through the gas phase. The removal efficiency can
be calculated simply by taking the ratio of the difference in the inlet and outlet
concentrations of the compound in the gas phase to the concentration of the
compound at the inlet.  It was found that the amount of compound removed from the
gas phase that can be accounted for by the increase in the liquid phase concentration
of the compound was negligible.  This meant that the compound removed in the
biofilter by the trickling nutrient flow was negligible as compared to the feed rate of
the compound.

      Figure 1 shows the percent removal efficiency for the five influent compounds
as a function of time.  Note that the percent removal efficiency for TCE is increasing as
the microorganisms are getting acclimated to the chemical. Measurements of the
cumulative net increase in carbon dioxide concentration, between the inlet and outlet
gas streams, have been made to confirm the overall carbon balance.  Measurements of
the increase in concentration of the  chloride ion in the liquid nutrient flow have been
made to confirm the degradation of the chlorinated compounds.  No degradation
products were found to exist, as determined by GC and  GC/MS analysis, in the outlet
gas stream. Careful measurement of the total gas phase pressure drop allows an
indirect measurement of the average biofilm thickness.  This parameter has been used

to confirm the validity of a lumped parameter dimensionless mathematical model, which
can be used to scale-up the biofilter.
       It has been shown that a biofilter is a viable technology for treating gas phase
organic contaminants. Complete aerobic degradation of trichloroehylene, although at
less than  100% removal efficiency, has been  demonstrated in the novel biofilter.
Furthermore, it has been demonstrated that the straight passages biofilter does not
plug-up due to biomass growth, as in the case of packed beds, and has an overall
lower gas phase pressure drop.






Carlson D.A. and Leiser, C.P. Soil beds for the control of sewage odors. J. Wat.
Pollut. Contr. Fed. 38:  829, 1966.

Ottengraf S.P.P. and van den Oever,  H.C. Kinetics of organic compound
removal from waste gases with a biological filter. Biotech. Bioeng. 25: 3089,

Ottengraf S.P.P., et. al. Biological Elimination of Volatile Xenobiotic
Compounds in Biofilters.  Bioprocess Engineering.  (Netherlands) 1: 61, 1986.

Ottengraf S.P.P. Biological Systems for Waste Gas Elimination., Trends
Biotechnol.  (Netherlands), 5/5, 132, 1987.

Brauer H. Biological Purification of Waste Gases. International Chemical
Engineering. 26, 3, 387, 1986.

Bishop F. and Govind, R. Degradation of gas phase contaminants in a Biofilter
Disclosure.  August 7, 1990.
Govind R. Biodegradation of organics in a Biofilter,  Quarterly Reports
Submitted to the Project Officer, U.S. EPA, 1990-1991.
        0                        30
                                  Time (day")

      Figure  1: Removal Efficiency  for the straight passages biofilter

                           POTW TREATMENT OF CERCLA LEACHATES

                E. Radha Krishnan, Roy C. Haught, Ruma Nath, and Srinivas Krishnan
                                         IT Corporation
                                       11499 Chester Road
                                     Cincinnati, Ohio  45246

                            Makram T. Suidan and Mohammed N. Islam
                        Department of Civil and Environmental Engineering
                                      University of Cincinnati
                                   Cincinnati, Ohio 45221-0071

                                       Richhrd C. Brenner
                              U.S. Environmental Protection Agency
                                  26 W. Martin Luther King Drive
                                     Cincinnati, Ohio  45268


     A study was conducted at the U.S. EPA's Test & Evaluation (T&E) Facility in Cincinnati, Ohio, to
investigate the effectiveness of two types of anaerobic fixed-film biological reactors in pretreating
hazardous landfill leachates containing synthetic organic chemicals (SOCs) prior to discharge to publicly
owned treatment works (POTWs).  Various anaerobic treatment processes have been used successfully
In the past to treat municipal leachates, with emphasis placed on chemical oxygen demand (COD)
removal. This study evaluated the processes of anaerobic biodegradation using upflow, packed-bed,
anaerobic filters (bench-scale and  pilot-scale) and an upflow, granular activated carbon (GAC),
expanded-bed, anaerobic reactor (bench- scale). These units are highly suited  for treating high strength,
Inhibitory wastes similar in characteristics to the leachate used in this study.

     Conventional wastewater treatment plants are often incapable of satisfactory removal of hazardous
substances from polluted water. The current method for treating hazardous landfill leachates usually
involves aerobic treatment, which may be inadequate under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) because of the following  reasons:

     a) Air stripping of volatile organic compounds,
     b) Incomplete treatment of semivolatile organic compounds, and
     c) Difficulty in degrading chlorinated compounds.
                                           i                     .              .
     Anaerobic biological pretreatment is expected  to reduce such problems because of the
substantially smaller volume of exhaust gas produced and the reductive dehalogenation capabilities of
anaerobic microorganisms.  The leachate for th? study was obtained from a  large commercial municipal
landfill (Rumpke) in Georgetown, Ohio. The leachate was  rendered hazardous by supplementing it wjth
a mixture of ten volatile and four semivolatile organic compounds. A list of these 14 toxic; organic
compounds, with their corresponding target concentrations, is provided in Table 1.

     The goals of this study were to:  1) establish the effectiveness of anaerobic pretreatment using
GAC, expanded-bed, anaerobic reactors and upflow, packed-bed, anaerobic filters in removing organic
compounds, Including chloroform;  2) compare the performance of the bench-scale, upflow, packed-bed,
anaerobic filter (B1) versus the GAC, expanded-bed, anaerobic reactor (B2);  3) compare the
performance of the bench-scale, upflow, packed-bed, anaerobic filter (B1) versus a similarly-operated
pilot-scale, packed-bed, anaerobic filter (P1); 4) evaluate the toxicity of chloroform in removal of toxic

organics in the leachate in each of the three bioreactors; 5) observe potential problems such as bed
plugging and calcium carbonate deposition on the GAG medium; and 6) determine the actual retention
time of the contaminants in the bench- and pilot-scale, packed-bed, anaerobic filters using lithium
chloride as a tracer material.  This paper reports on the performance of these systems over a period of 2
years during which effective process control was maintained.  The experimental treatment systems were
operated at the U.S. EPA T&E Facility in Cincinnati, Ohio.

Concentration (ua/L)
                 Acetone                                   10,000
                 Methyl Ethyl Ketone                          5,000
                 Methyl Isobutyl Ketone                       1,000
                 Trichloroethylene                             400
                 1,1-Dichloroethane                            100
                 Methylene Chloride                          1,200
                 Chloroform                             0 to 2,000
                 Chlorobenzene                              1,100
                 Ethylbenzene                                 600
                 Toluene                                    8,000

                 Phenol                                      2,600
                 Nitrobenzene                                 500
                 1,2,4-Trichlorobenzene                        200
                 Dibutyl  Phthalate                             200


     The bench-scale anaerobic pretreatment units consisted of an upflow, packed-bed, anaerobic filter
(B1) and a GAG, expanded-bed,  anaerobic reactor (B2). These units were fabricated using plexiglass
and installed to treat municipal leachates rendered hazardous by the addition of 14 SOCs.  The growth
support medium in the B1 column (15.2 cm diameter x 122 cm high) was 2.54-cm diameter
polypropylene pall rings. The growth support medium in the B2 column (10.2 cm diameter x 106 cm
high) was 1.0 kg of 16 x 20  U.S.  Mesh Granular Activated Carbon (GAC).  Each of these bioreactors was
coupled with a second-stage, bench-scale, aerobic treatment system (simulating a POTW) consisting of
a primary clarifier, aeration basin, and secondary clarifier.  Raw municipal leachate was fed to each
bench-scale anaerobic reactor from a sealed, chilled, mixed, oxygen-free, stainless steel reservoir
through stainless steel lines. A stock solution of the  SOCs was fed into the suction side of each recycle
loop along with the leachate. The pilot-scale pretreatment system (P1) consisted of a 129-cm diameter
by 229-cm high upflow anaerobic filter,  packed with polypropylene rings, coupled with a second-stage,
pilot-scale, primary clarification/activated sludge aerobic system.  All three anaerobic pretreatment units
were operated at 35°C and a pH range of 7-7.5.

     All the bioreactors were fed with the Rumpke leachate, which was characterized by COD levels
ranging between 400 and  2,500 mg/L.  Due to its relatively low biodegradable content during the first 6
months of the project, the leachate was supplemented with a mixture of equal portions of organic acids
(acetic, propionic, and butyric) to maintain the bioreactor influent COD at 1,600 mg/L  This practice was
discontinued during the course of the study in order  to evaluate biodegradation under the natural
varying COD concentrations of the leachate. Leachate sulfate concentrations ranged from 3 - 300 mg/L.

     The flow rate to the B1 and B2 columns was nominally set at 10 L/day. The leachate flow rate into
 P1 was Initially regulated at 0.57 L/minute.  Off gases from each of the bioreactors were measured using
 wet-tip gas meters, connected at the top of each of the units.  Daily measurements of total gas
 production, feed flow rates, spike flow rates, reactor temperatures, and reactor pH values were recorded.
 Samples were analyzed throughout the test period for SOCs, total and soluble COD, sulfate, and off-gas
 composition. Metals, SOC composition in the off gas, total and volatile suspended solids, and ammonia
 nitrogen were measured weekly on selected sampling periods.

     The experimental  period can be divided into five distinct phases for the B1, B2, and  P1 bioreactors.
 During Phase 1, each of the systems was acclimated for approximately two months to the Rumpke
 leachate.  In this phase, the leachate flow rates in the bioreactors were gradually increased and adjusted
 at design specifications. The leachate flow rate was adjusted to 10 L/day in each of the bench-scale
 bioreactors. This resulted in an empty-bed contact time (EBCT) of 2 days in bioreactor B1, and an
 unexpanded EBCT of 8 hours in bioreactor B2. During this phase, the P1 bioreactor was adjusted to an
 EBCT of 4 days corresponding to a leachate flow rate of 0.57 L/minute (820 L/day).  Bioreactors B1, B2,
 and P1 were inoculated with 100% concentrations (Table 1) of 13 of the 14 synthetic organic
 compounds (SOCs) within one month at incremental rates of 33% and 66% of the target level;
 chloroform was not introduced until the later stages of the study because of its potential toxicfty.  Phase
 2 experienced the design flow rates and 100% SOC concentrations (without chloroform) for five months.
 During Phase 3, the leachate flow rate was doubled for pilot-scale bioreactor P1, thus establishing an
 EBCT of 2 days similar to that in bioreactor B1. Recirculation rate ratios were also made  comparable for
 bioreactors B1 and P1 during this phase. During Phase 4, chloroform was included in the SOC mixture
 (at a concentration of 2 mg/L) for all three bioreactors.  Phase 5 can be divided into several distinct
 stages for the three anaerobic pretreatment units.  First, leachate flow rates were doubUsd (20 L/d) for
 bioreactors B1 and B2, thereby halving the EBCT in B1 and B2 to 1 day and 4 hours, respectively.
 Second, carbon washing was initiated on bioreactor B2 to evaluate the effects of carbon washing on the
 GAC system. Third, chloroform was removed from bioreactor P1 's SOC spike because of possible toxic
 effects, and the system was monitored to determine if performance could be recovered to pre-
 chloroform addition levels.


     Both B1 and B2 bioreactors were capable of removing through biodegradation most of the
 CERCLA compounds at efficiencies of 90% or higher, with the exception of 1,1-dichloroethane and
 dibutyl phthalate (which were removed at 80%! efficiency).  The packed-bed bioreactors removed
 ketones more efficiently than the expanded-bed bioreactor. Over 90% removal was observed for the
following compounds in B1, B2 and P1 systems: acetone, methyl ethyl ketone, methyl isobutyl ketone,
trlchloroethylene, methyiene chloride, nitrobenzene, and phenol. All the semivolatile compounds, with
the exception of dibutyl phthalate, were removed at 95% efficiency in the B1 and B2 systems.  In the P1
 bforeactor, over 75% removal was observed for toluene, over 60% removal for ethylbenzene and
chlorobenzene, and over 80% for 1,2,4-trichlorpbenzene and dibutyl phthalate. All of the volatile
aromatics showed higher removal efficiencies in the expanded-bed bioreactor compared to the packed-
bed bioreactors.

    The COD removal efficiency in the B1 and B2 systems averaged 42% and 48%, reispectively.
During the period  of the volatile acids addition, the primary COD removal mechanism was
methanogenic. After the volatile acids addition was stopped and the feed COD decreased, the COD
removal mechanism was due to a combination of methanogenesis and sulfate reduction.  The average
sulfate reductions in the GAC expanded-bed bioreactor and the anaerobic filters were 71 % and 65%
respectively, corresponding to an Influent sulfate concentration of 116 mg/L.

     The performance of the B1, B2 and P1 systems was similar prior to the introduction of chloroform
in the spike solution. Within 3 weeks after the addition of chloroform into the three units, however, the
P1 bioreactor showed a decline in the removal of some of the SOCs (including chloroform). SOC
removals continued to decline over a period of 4 months, at which time chloroform addition to the spike
mixture was discontinued for the P1 bioreactor. The B1 and B2 systems continued to receive
chloroform at a concentration of 2 mg/L until the termination of the study because the removal
efficiency in both bioreactors averaged 95%.

     During the initial period of the study (about 350 days of bioreactor operation), the less
biodegradable but more adsorbaWe aromatic compounds were removed more efficiently in the GAG,
expanded-bed anaerobic reactor than in the upflow, packed-bed, anaerobic filter.  However, after about
400 days of operation, problems such as bed plugging and calcium carbonate deposition on the GAG
medium disrupted the methanogenic activity in the B2 column. This problem was circumvented by
periodically washing 5% of the total carbon contained in the expanded-bed system using 0.1N HCI.
Therefore, in the long run, the anaerobic  upflow packed-bed filter systems were less susceptible to
operational problems and more  conducive to the growth of methanogens compared to the expanded-
bed anaerobic unit.  It should be noted, however, that the bench-scale, GAG, expanded-bed bioreactor
operated at one-sixth the empty-bed contact time of the bench-scale anaerobic filter and, for part of the
study, at one-twelfth the empty-bed contact time of the pilot-scale anaerobic filter.

     In order to verify the actual retention time of leachate in the B1 and PI packed-bed systems,
lithium chloride tracer studies were conducted.  The tests were conducted first, after the fourth phase of
the study (without cleaning the bioreactor media), and then after completion of the study (following
cleaning and repacking of the media).  Results of the first tracer study indicate some plugging in the P1
bioreactor.  Results  of the second tracer study are expected shortly.  The observed media plugging and
probable channeling in the.P1 unit may explain, at least in part, the poorer performance of the pilot-scale
anaerobic filter compared to the bench-scale anaerobic filter.

                                       OF 77V-S77I/BIOVENTING

           Gregory D. Sayles1, Robert E. Hinchee2, Richard C. Brenner', Catherine M. Vogel3 and
                                             Ross N. Miller4

                 1 U.S. EPA, Risk Reduction Engineering Laboratory, Cincinnati, OH  45268
                      2Battelle Laboratories, Columbus Division, Columbus, OH 43201
              3 U.S. Air Force Engineering Services Center, Tyndall Air Force Base, FL  32403
          4 U.S. Air Force, Center for Environmental Excellence, Brooks Air Force Base, TX 78235


        Bioventing is the process of supplying oxygen in-situ to oxygen-deprived soil microbes by forcing air
through contaminated soil at low air flow rates.  Unlike soil venting or soil vacuum extraction technologies,
bioventing attempts to stimulate biodegradative activity while minimizing stripping of volatile organics.  The
process destroys the toxic compounds in the ground.  Bioventing technology is especially valuable for treating
contaminated soils in areas  where structures and utilities cannot be disturbed because the equipment needed (air
injection/withdrawal wells,  air blower, and  soil gas monitoring wells) is relatively non-invasive.

        The U.S. EPA Risk Reduction Engineering Laboratory, with resources from the U.S.  EPA
Bioremediation Field Initiative, began two parallel 2-year field studies of in-situ bioventing in the summer of
1991 in collaboration with the U.S. Air Force.  The field sites are located at Eielson Air Force Base (AFB)
near Fairbanks, Alaska, and Hill AFB near Salt Lake City, Utah.   Each site has jet fuel JP-4 contaminated
unsaturated soil where  a spill has occurred in association with a fuel distribution network. With the pilot-scale
experience gained in these studies and others, bioventing should be available in the very  near future as an
inexpensive, unobtrusive means of treating large quantities of organically contaminated soils.


Eielson AFB
        At Eielson AFB, we are studying bioventing in shallow soils in a cold climate in conjunction with soil
wanning methods to enhance the average biodegradation rate during the year.  Roughly  1 acre  of soil is
contaminated with JP-4 from a depth of roughly 2 ft to the water table  at 6-7 ft.  Initial (pre-bioventing) soil gas
measurements taken in July 1991 ranged from 600-40,000 ppm total hydrocarbons, 0-13% O2, and 10-18%
CO2, indicating oxygen-limited biological activity and a high degree of contamination. Thus, addition of oxygen
as air to the site would be expected to increase the rate of biodegradation.  In comparison, atmospheric air
composition includes 21% O2 and 0.03% CO2.

        The test area was established by laying down a relatively uniform distribution of 24 air
injection/withdrawal wells and constructing  test plots within this test area (see Figure 1).  Air is injected from 2-
6 ft deep at an overall rate  of 60 cfm to  the test area or 2.5  cfm to each active well.  Thus, the test plots should
receive relatively uniform aeration.  Three 50-ft square test plots were  established. One plot is being used as a
control, i.e., bioventing only, no heating. The remaining two plots are being used to evaluate separately the
following two strategies of  combining bioventing with wanning of the soil above ambient temperature to
increase the rate of biodegradation year-round: (1) passive solar warming using plastic covering, and (2) active
warming by applying warm water from soaker hoses just below the surface. Water is applied at roughly 35°C
and an overall rate of roughly 1 GPM to the actively-warmed plot.

        In addition to the network of air injection/withdrawal wells, three-level soil gas  monitoring wells and
three-level temperature probes were installed throughout the site between 2 and 6 ft deep. In addition, one air
injection/withdrawal well and one soil gas monitoring well was installed in a nearby uncontaminated area for

 background measurements.  The venting of air and the trickling of unheated water to the actively-warmed plot
 began in September 1991.  Warming of the water began in October, 1991.  A plan view of the installation is
 presented in Figure 1.

         Periodically, in-situ respirometry tests are conducted to measure the in-situ microbial oxygen uptake
 rates.  Such measurements indicate the relative rate of biodegradation of the contaminants.  These tests involve
 temporarily (4 to 8 days) shutting the air off and monitoring the soil gas oxygen concentration with time. The
 decrease in oxygen concentration with time indicates a relative biodegradation rate at that time during the study.
 Oxygen uptake due to oxygen demands other than biological activity is calculated by conducting a parallel shut-
 down test in the  (uncontaminated) control area.  These tests allow estimation of the biodegradation rate as a
 function of ambient temperature and soil warming technique. Quarterly in-situ respiration tests will be
  - Groundwat*r mentoring vwl
• • Air InjMtion/wtthdrawal ml
S - Thr»-l«wl sol gai prob*
T - Thr»-towl thwmocoupte prob*
O - Air InjaeOon/wtthdraml MX
   (Currant* not h UM)
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                                               Bunding 1315
      Figure 1.  Plan view of the joint U.S. EPA and U.S. Air Force bioventing activities at Eielson AFB.

         At Hill AFB in Utah, we are evaluating bioventing at greater depths.  A 1-acre site is contaminated
with JP-4 from depths of approximately 35 ft to perched water at roughly 95 ft.  Here, bioventing, if
successful, will stimulate biodegradation of the fuel plume under roads, underground utilities, and buildings
without disturbing these structures.  A plan view of the installation is shown in Figure 2.  The air injection well
is indicated.  "CW" wells are soil gas "cluster wells" where independent soil gas samples can be taken at 10-ft
intervals from 10-90 ft deep, and "WW" wells are groundwater monitoring wells.  A cross-sectional view along
the path AA' in Figure 2 is shown in Figure 3.  Air is currently being injected from one well into the plume at
a rate of 40 cfm at depths from 30-95 ft.
         An inert gas tracer study,  regular soil gas measurements at several locations and depths, and semi-
annual in-situ respiration tests are planned to demonstrate the effectiveness of delivering oxygen and stimulating

biodegradation in a large volume of soil of substantial depth.  The inert gas tracer study involves temporarily  .,.
replacing the injection of air with the injection of argon or helium and observing the transport of gas in the soils
by monitoring for the inert gas at the various soil gas wells. The air injection rate will be increased semi-
annually to evaluate the trade-off between the gain in area of influence of the injected air for bioremediation and
the additional loss of air and volatilized organics to the atmosphere at the soil surface.
   Figure 2. Plan view of the joint U.S. EPA and U.S. Air Force bioventing activities at Hill AFB. CW are
 cluster soil gas monitoring wells, WW are groundwater monitpring wells, and the air injection well is indicated.
                 Path AA' indicates the location of the cross-sectional view shown in Figure 3.

 RESULTS                                                              ,                         "

         Progress to date includes installation of the pilot-scale equipment and initial soil sampling for total
 hydrocarbons during July and August 1991, continuous soil temperature monitoring since August 25, and an
 initial pre-heating in-situ respiration test conducted in early October (data not available at this time).  Figure 4
 shows soil temperatures at one location at three different depths for the actively-warmed and (uncontaminated)
 background area as a function of time through November 15,  1991 (data for the other plots was; not available at
 this time).  Clearly, the active-warming strategy is functioning well: as ambient temperatures fell during the
 fall, the actively-warmed plot remained above 10°C (except for a short period when soil temperature decreased
 to between 8 and 9°C), while the temperature at the background location dropped steadily toward 0°C.  The
 background area should drop well below 0°C during the winter since the annual average soil temperature at this
 location in Alaska is only about -2°C.  Note that the active warming is maintaining the temperature in the
 actively-warmed plot near the average summer temperature of about 11°C.
         Several problems caused inefficient performance  of the actively-warmed plot in its early operation.
 The first problem encountered was reduced water  flow rate from,the buried soaker hoses due to the     ;
 accumulation of silt around the hoses.  The low water flow rate resulted in the  steady decline of the temperature

between Day 30 and Day 56 (Figure 4).  Our goal was to maintain the soil in the actively-wanned plot between
10 and 20°C.  To remedy this situation, weekly high-pressure pulses are employed to clear the hoses. The
pulsing began on Day 56 and quickly resulted in increased soil temperatures (Figure 4).


   4750 -




   4S7O -  [E

CW - Son Gas Clutter Well
03 • Sand with Gravel and day
                                      D • Screened Interval   fHM - Sand wtth Clay Cloto
                                     =|-SiltySand        |  |- Sand
                                                                                       <- 4770
Perched Water
(Approx. Surtece)
Figure 3. Cross-sectional view at Hill AFB along path AA' (Figure 2) showing the relative locations of the air-
injection well, soil gas cluster and  groundwater monitoring wells, and some geological features of the site.
                                                   Time (Days)
    Figure 4. Temperature as a function of time at one location and three depths within the background and
                                   actively-warmed plots at Eielson AFB.

        Second, the soils were not being adequately aerated, probably because a large fraction of soil pore   :
 volume flooded due to the continuous trickling of water onto the plot. Table 1 shows the range in soil oxygen
 concentration measured in the three plots immediately before the initial respiration test.  Ideally, the forced
 aeration should result in a soil oxygen composition of at least 5-10% to avoid oxygen-limited microbial activity.
 The low oxygen concentration observed in some portions of the actively-warmed plot indicated rapid microbial
 activity, but also demonstrated that air was not being delivered efficiently to those areas.  In December, semir ,
 weekly  cycling of the water flow rate from high to very low was initiated to decrease the average  amount of
 water held in the soil in an attempt to increase the water-free pore volume.

Oxygen Cone. Range, %
        Progress to date at Hill AFB includes completion of the installation of the wells shown, in Figures 2 and
3 and initial soil sampling for total hydrocarbon levels as a function of depth. An example of one total
hydrocarbon distribution is shown in Figure 5 for soil taken during installation of well CW6.  This initial
characterization will be compared to final soil sampling planned for Summer 1993 to calculate net loss of
hydrocarbons due to bioventing.  The inert gas tracer study is planned for Spring 1992.
u -
30 -
60 -
7O -
80 -
90 -
inn -


        This paper summarizes the first 6 months of a 2-year joint U.S. EPA/U.S. Air Force study of in-situ
bioventing.  Already, the work at Eielson AFB has shown that active soil warming techniques are successful in
maintaining soil at warm temperatures during cold ambient temperatures.  The most efficient means of
delivering warm water to avoid blockage of the buried hoses, and the optimal water and air flow rates that
provide adequate warming and aeration, continue to be investigated.

        The bioventing studies at Hill and Eielson AFBs are generating valuable pilot-scale performance data
and field operational experience for a technology that in the near future could provide an cost-effective means of
in-situ cleanup of organically contaminated unsaturated soils. In addition, the soil warming techniques
investigated here will be applicable to enhancing biological treatment rates of unsaturated soils for any
bioremediation technology at any location where a significant portion of the year is too cold to allow satisfactory
biological activity.

               John R.  Haines,1 Todd Harrington,2 Mohammed Islam,2
                   Kevin Strohmeier,2 and Albert D.  Venosa1  .
                            and Environmental Engineering
                  Mail Location 71, University of Cincinnati
                             Cincinnati,  OH  45221

               2U.S. EPA, Risk Reduction Engineering Laboratory
                             Cincinnati,  OH  45268
      The effectiveness of bioremediation products intended for use on spilled
petroleum or refined petroleum products must be evaluated prior to a spill
occurrence.  The need for development of a test protocol for product
evaluation has led to initiation of work at RREL in Cincinnati.  Biological
degradation of petroleum hydrocarbons requires molecular oxygen as a terminal
electron acceptor.  The current method for testing efficacy of bioremediation
products involves monitoring disappearance of oil constituents over time by
gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS), both
of which are tedious and expensive.  Our laboratory is developing methods by
which 02 consumption and C02 production  can  be  correlated with  disappearance
of oil compounds.  This correlation, once established, will permit examination
of bioremediation products based oh 02 consumption/C02 production with  minimal
chemical analysis.  The goal of this work is to establish reliable methods for
assaying potential effectiveness of bioremediation products under various

      Protocol development will encompass seawater, freshwater, sediments,
beach material, and soils.  Various types of crude oil or refined products
will be examined as well as the effects of temperature and salinity on the
efficacy of bioremediation products.  Oxygen consumption, bacterial numbers,
and changes in oil chemistry will be measured over time.  When data collection
is completed, the various parameters will be correlated with oil disappearance
as measured by gas chromatography, and simpler, less expensive methods will be
proposed as a measure of bioremediation product effectiveness.

      This paper reports on the effect of temperature on microbial  degradation
of crude oil in closed systems.  Degradation was tracked by measuring oxygen
uptake in respirometers, decreases in aliphatic constituents of the oil, and
changes in oil degrader population^ over time.   Results will have an impact on
how bioremediation protocols will be conducted for determining product

 changes  in  oil  degrader populations  over time.   Results  will  have an  impact on
 how bioremediation  protocols  will  be conducted  for  determining  product
       Inoculum  cultures were maintained  by periodic  (three week)  transfers
 into  Bushnell-Haas  salts medium  supplemented with  1.0% w/v Alaska North  Slope
 (ANS)  crude  oil.   Inocula were prepared  by centifuging 300 ml of  culture and
 resuspending the  pellet in  a final  volume  of 60 ml of culture supernatant.
 Each  respirometer flask was inoculated with 1 ml "of  the concentrated  culture,
 except those flasks  serving as unihoculated controls.  The inoculum yielded
 about  2.5 X  104 cells/ml final concentration.  Flasks containing oil received
 5000 mg/L of the  ANS oil.

       Oxygen consumption was measured using N-CON respirometers
  (Larchmont,  NY). The N-CON system  uses  sensitive pressure switches to measure
 pressure drops  in sealed flasks  caused by  oxygen consumption.  The system then
 activates microsolenoid valves to feed 02 from a cylinder to balance the
 pressure in  the flasks with reference pressure cells.  The computer then
 calculates oxygen consumption based on the solenoid  valve volume  and number of
 pulses required to balance  the system.  The flask caps also include a
 reservoir for KOH solution  for absorbing C02 produced by oil  degrading
 microorganisms.   The KOH traps can  be renewed by means of a syringe valve and
 cannula penetrating the flask cap.

       Populations of microorganisms in the flasks were measured each time a
 sample series was collected for  chemical analysis.   Small samples (10-15 ml)
 of the flasks' contents were placed in a sterile reservoir on a Beckman  Biomek
 1000 laboratory robot.  The Biomek  fills a 96 well tissue culture plate with
 sterile medium, transfers and performs serial 10 fold dilutions of the sample,
 and layers oil (2 uL No. 2  fuel  oil) on the surface  of each well
 automatically.  The plates  thus  prepared are then covered and insulated  in the
 dark at room  temperature (22°C)  for 14 days.  After incubation,  a  multichannel
 pipettor is  used  to deliver 50 uL of a 0.1% w/v solution of
 p-iodonitrotetrazolium violet to each well of each plate.  After 30 minutes,
 positive wells were scored  by counting the pink wells in each row of
dilutions.   The data produced were for an eight tube Most Probable Number
 (MPN) procedure and the MPN of oil degraders per ml was computed using a PC
 based Fortran program.

      The remaining contents of each respirometer flask were treated by adding
 50 ml of CH2C12 to  initiate extraction.   The samples were extracted with
CH2C12 and had the CH2C12 exchanged with hexane prior to silica gel
chromatography.   The crude hexane extract was applied to a 60-200  mesh silica
gel column  for fraction separation.  The alkarie fraction was eluted by washing
the column  with hexane and the aromatic fraction was eluted  by washing
the column  with benzene:  hexane  (1:1) after the hexane washing.

      The respective fractions were then concentrated to a standard volume and
analyzed by GC and GC-MS.   The analytical conditions were:  injector

temperature, 250°C;  oven temperature programmed from 5 min initial  hold at
50°C to 300°C at  7°C/nrm; with a hold at 300°C for 35 min; FID detector, 350°C.
In the case of the GC-MS the ionization voltage was 70 ev.  The carrier gas
was He at 5 mL/min and the column was a 0.75mm  X 30mm DB-5 from Supelco,
Supelco Park, PA.  The GC was a Hewlett Packard 5880A and the GC-MS was a
Hewlett Packard 5970A with a 0.25mm X 30mm DB-5 column.  The other parameters
were the same as for the GC except the program rate was 8°C/nrin.   Oil  residue
weight was measured by drying a portion of the CH2C12 extract  and  weighing the
dried residue.

RESULTS                 '    '     :

      The oxygen uptake curves at 15° and 25°C  produced  by microorganisms
incubated with ANS crude were quite different.  At 15°C, the onset of oxygen
uptake occurred at 3 days and slowed in rate at 6 days.  At 25°C oxygen uptake
was rapid after 2 days and slowed after 5 days.  Uptake was more rapid at 25°
than at 15°.  At 15°C,  oxygen  uptake was  about  2500  mg/L,  which  is  about  23%
of theoretical. At 25°C, oxygen uptake was about 4500 mg/ L, which is about
42% of theoretical.  Potential oxygen uptake was calculated based'on complete
conversion of oil carbon to C02.   Total  conversion would have consumed about
10,600 mg/L 02.  The carbon content of the ANS crude was 82% based on
elemental analysis of duplicate samples by an  independent laboratory.

      Over the period of this experiment, numbers of oil degraders followed a
typical growth and decline pattern  (Fig.l).  At day zero the population  in
each flask was about 2.5 X 104 cells per mL. By day 9 the population had
increased by over five orders of magnitude, thereafter  the  population
declining slowly to about 107 cells per mL.

      Analysis of the oil content of flasks over the period of the experiment
yielded interesting results.  During incubation at 15°C, 95% of the resolvable
alkanes were consumed by day 5 of the experiment.  No aromatic hydrocarbon
data were available at this writing.  Degradation of labile alkanes was
essentially complete by day 5.  Oxygen uptake  was still  active after day  5,
indicating that microorganisms wefe consuming  less readily  resolved
hydrocarbons.  Analysis of the data showed very little  preference  for
degradation of normal alkanes over  branched alkanes  such  as pristane.
Pristane decreased in concentration almost as  rapidly as  heptadecane.  This
indicates some organisms can adapt  to utilize  branched  chains as well  as
straight chains  quite readily.  Oil residue weight had  declined from about
3500 mg/L to 3200 mg/L  at the end of the  experiment.  Figure 2 shows the
results of oil analyses from this experiment.

       Even though easily analyzed hydrocarbons were  consumed, significant
quantities of oil persisted in the  flasks. The easily resolved hydrocarbons
measured by GC represent a small fraction of the total  oil  mass.   Our
laboratory estimates the n-alkane fraction to  be.about  1% of the  oil.
 The difference  between oxygen uptake and oil  residue weights may  be due to
the fact that oil residue methods only provide a general  mass estimate.   The
extraction procedure will extract any compound that  preferentially partitions

 into CHjClj over water.  Some of these compounds will include partially
 metabolized  oil  compounds  and cellular lipids.

       A subsequent experiment was  conducted to  evaluate the response of
 microorganisms to  six different kinds of oil  or refined products.   Crude oils,
 light Arabian (LA),  South  Louisiana (SL),  Prudhoe  Bay (PB), and Weathered PB
 (WP) and Number 2  (F2),  and Number 6 (F6)  fuels were incubated  at  15 and 25°C
 as  previously described.   Trials were conducted with nutrients  or  without
 added nutrients  at both  temperatures.  In  general,  oxygen  uptake at 15°C  was
 lower than at 25°C.  At 15°C, oxygen consumption was about 3700 mg/L for LA,
 3200 mg/L for F2,  2700 mg/L for SL,  1600 mg/L for  PB and WP,  and 1000 mg/L for
 F6  with nutrients.   Without nutrients 02 consumption was lower.  The onset and
 early rate of oxygen uptake was the same for  LA and PB  crudes beginning  at
 three days.   Degradation of LA  continued rapidly until  12  days  and slowed.
 Degradation  of PB  slowed after  six days.  Degradation of SL began  at four days
 and slowed at seven  days.   WP oxygen uptake began  at five  days  and slowed at
 seven days.   Oxygen  uptake with F2 began at five days and  remained mostly
 constant until  18  days.  F6 oxygen uptake  started  at five  days  and remained
 slow for the  entire  experiment.
      The results of work  to date  show that the performance of microorganisms
degrading oil varies significantly with temperature and "nutrients  as expected.

      Our results indicate that the major portion of oxygen consumption  is
complete by less than  14 days of incubation at either 15 or 25°C.  The readily
degraded compounds are largely consumed in this period and therefore
experiments evaluating bioremediation products may be completed  in less  than
30 days.  Oil residue weight may not be a good indicator of degradation.  Long
period studies can concentrate on  metabolism of resistant structures left in
crude oils after preliminary weathering.  The variation in 02 consumption
resulting from different kinds of  oils shows that bioremediation products may
need to be tailored for the specific type of oil involved in a spill.
The data obtained with multiple oils also will aid in planning future
experiments with regard to sample  collection and analysis.  The lighter  fuels
and crude oils yielded the highest 02 consumption.   The lowest 02 uptake  was
associated with the heavy No.6 fuel and weathered PB oils.

      Testing of bioremediation products will  require careful attention  to the
parameters of microbial growth in the testing sequence.  The type of product,
the oil  product the remedial product is intended for,  the environmental
parameters affecting the remedial product, and the time scale that remedial
products are intended to act in, will require that testing protocols be
flexible in methodology and interpretation.

      Future work will  expand upon the preliminary results obtained to date in
this work.

                         10     15    20     25
                           TIME, DAYS
Figure 1. Most Probable Number of Oil Degraders over Time.

     35000  -*=•
     30000  --
     25000  --
J 20000  H-
     15000  --
      5000  --
                                                         target alkanes

                                                         residue weight
—  4000
—  3500
—  3000
—  2500
    2000 -
->-  1500
—  500
            0      2       4      6      8      10      12     14     16     18

                                         time, days
Figure 2.   Decline in Target Alkanes and Residue Weight as a Function of Time at


                                    l                                          - i

  Ashutosh  Gupta1, Joseph  R. V. Flora1, Gregory D. Sayles?, Makram T. Suidan1

                     1 Civil and Environmental Engineering
                   Mail  location 71,  University  of Cincinnati
                             Cincinnati,  OH 45221
                 U.S. EPA, Risk Reduction Engineering Laboratory
                              Cincinnati,  OH 45268
    The highly chlorinated methanes biologically degrade only extremely slowly
under  aerobic  conditions.   For example,  in  conventional wastewater  treatment
facilities,  these  toxic  compounds  would  likely  be  untreated  and  either  pass
through the  aerobic  bioreactor and appear in  the plant  effluent  or  be stripped
to the atmosphere  by the aeration.   Cost-effective technologies  to  destroy
these  priority pollutants  are  required due  to their prevalence at Superfund
sites, in landfill leachates and in industrial  effluents.  For example, the
1986 National  Priorities List  (NPL) database  indicates  that  chloroform  and
carbon tetrachloride appear at 24% and 7% of  all NPL sites,  respectively.

    It  is  well  known  that anaerobic biological treatment can  degrade the
highly chlorinated methanes efficiently  while metabolizing more  easily
degradable primary substrates.  However, recently  completed  research by the
U.S. EPA Risk  Reduction  Engineering Laboratory  revealed that chloroform can
severely limit the ability of  methanogenic  anaerobic treatment systems to
process readily, biodegradable  and  more refractory  constituents of a
multicomponent hazardous waste stream.                             :

   The type  of anaerobic environment utilized appears to  influence  the  impact
that these compounds  have  on an anaerobic process.   Recent data  collected from
a leachate-treatability  study  conducted  at  the  U.S.  EPA Test and Evaluation
Facility using parallel  anaerobic  reactors  operating under methanogenic and
sulfate-reducing conditions, respectively,  revealed  that sulfate-reduction
promoted efficient chloroform  degradation while, once again,  methanogenic
activity was adversely affected by  increased  levels  of chloroform in the

   Thus, the objective  of this study is  to  rigorously investigate the
anaerobic biodegradability  of  chlorinated methanes with primary emphasis on
chloroform.  The fundamental kinetics of transformation of carbon
tetrachloride,  chloroform,  dichloromethane  and  chloromethane are studied under
methanogenic and sulfate-reducing environments.  These kinetics are evaluated
in the presence of the co-substrates methanol,  formate and acetate.


   Six 10-liter stainless-steel chemostats  were assembled.   Each chemostat  is
equipped with  two constant  speed masterflex pumps to feed the nutrients and

the buffer.  The nutrients contain the necessary inorganic salts and vitamins,
while the buffers maintain a constant pH.  The masterflex pumps are channelled
through timers to enable variable flows.  The organic substrates are injected
with a 10-ml syringe pump.  The contents of the chemostats are kept completely
mixed with the aid of a variable speed mixer.  The primary substrate in the
feed to each chemostat and the corresponding anaerobic environment are listed
in Table 1.  The chloromethane will be an additional organic feed component.
Sul fate-reduction/Methanogenic
    The chemostats are operated at a 3  g/day COD loading.   Daily and  weekly
analyses are performed to monitor the performance of the chemostats.  The
daily  analyses include recording the feed rates of the buffer, nutrient, and
syringe pump (COD feed) solutions,  and measuring the pH, total gas production,
and temperature.  Appropriate  adjustments in the buffer solutions are made to
keep the pH constant  at 7.2.   Weekly analyses include measuring the COD and
sulfate concentration, volatile suspended solids (VSS), and volatile fatty
acids  (VFA) in the effluent. The percent composition of the effluent gas is
also determined.  These measurements allow  calculation of the fraction of the
COD removal attributable to methanogenesis  (methane formation), to sulfate-
reduction  (oxidation  of the organic feed components by the reduction of
sulfate),  and to  biomass production.  An example of the weekly COD balance is
presented  in Figure 1.  Steady state is confirmed and characterized by
constant levels of all parameters including measurement of the oxidation-
reduction  potential (ORP).

    In  the  methanogenic/sulfate-reducing systems,  an  abundance of iron  is
required as a microbial nutrient  and to precipitate the inhibitory sulfide
that is produced.  Iron is  introduced  in the chemostats with  the nutrient
solution.  Organic chelating agents have been used in the past to solubilize
iron in nutrient,solutions, but these  agents are not desirable as they serve
as  another source of  COD.   A detailed  investigation of the chemistry of the
anaerobic  environment resulted in an alternative procedure that does away with
these  chelating agents.


    As  of December 1991,  the first phase of the project was complete.   The
goal of the first phase was to obtain  an initial steady-state operation for
all the chemostats without  the presence of  chloromethanes.  Over four months

 of stable operating data, and weekly COD balance  on  all  the  chemostats
 indicate that the initial steady-state was  achieved  (an  example of the weekly
 COD balance for Chemostat I  is presented in  Figure 1).   To confirm steady-
 state, in-situ ORP measurements were performed  repeatedly.   The steady-state
 values for selected parameters are shown in  Table 2.  Note that the sum of the
 percent of COD removal by methanogenesis and by sulfate-reduction does not
 equal 100 because a fraction of the inlet COD is  used to produce biomass.
          2 -
          1 -
                                                          O influent
                                                          V gas + effluent
                                                          D effluent
    Figure 1. Weekly  COD  balance  for chemostat  I  through  December  4,  1991.

^   A  computer model  was developed to study the interactions of the various
ions present  in the systems. The  main motivation  for  this task was to  study
the effect of these interactions  on the availability  of the  nutrients,
especially in the case  of the sulfate-reducing  systems where large amounts of
sulfide are produced  that can cause precipitation of  the  important nutrient
metals.  A non-steady CSTR model  was prepared to  simulate equilibrium
interactions.  Refinement of this model is continuing.  The  results from the

model will be compared with experimental data.  These results will also be
presented at the symposium.


. • '• '
Removal of Inlet
Fraction of C
s %
OD Removal by
Sul fate-
reduction %

    As  expected,  the methanogenic systems  consumed  the  primary substrates  very
efficiently with all chemostats  exhibiting above 95% COD removal (Table 2).
However, the sulfate-reducing systems exhibited some more interesting

    i.       Acetate was readily  consumed by the sulfate reducers
            (chemostat IV).

    ii.      Although there was an abundance of sulfate in this
            chemostat feed (4500 mg/1), methanol was not consumed
            by the  sulfate reducers in chemostat V and no COD was
            utilized via sulfate-reduction.  While both the
            chemostats with methanol feed (chemostats  II and V)
            exhibited methanogenesis exclusively, differences were
            observed in their operation.  The most important was
            the difference in the ORPs, where the absolute value
            of the  ORP of the chemostat with sulfate was more than
            twice that of the chemostats with no sulfate.
            Consequently, very different behaviors between the two
            reactors are expected once the chloroform  feed starts.

    iii.     A competition was observed between sulfate reducers
            and methanogens for  formate utilization (chemostat
            VI).  Batch tests will be performed on the chemostat
            contents to evaluate the kinetic parameters in order
            to explain this behavior.

    The second  phase of the project  is  due to  start shortly.   During this
phase of the study, chloroform feed to the chemostats  will begin.  The results
of part of the second phase will also be presented at  the symposium.



                         Ronald F.  Lewis
                            U.S. EPA
                     26 West M. L.  King  Drive
                      Cincinnati, Ohio 45268

         Michael Smith, Judy Hessling,  and Majid Dosani
              International Technology  Corporation
                       11499 Chester Road
                      Cincinnati, Ohio 45246


     This  paper  is  a part  of  the  work conducted  for  a  joint
Superfund  Innovative  Technology  Evaluation (SITE)  project  and a
study for  the EPA's  Office  of  Solid  Waste  and Emergency Response
(OSWER)   that is  developing  information  for Best  Demonstrated
Available Technology (BOAT). The project was conducted at the U.S.
EPA Test and Evaluation  Center located at the Gest  Street Waste
Water Treatment Plant in Cincinnati,  Ohio.   The contaminated soil
chosen for the test  of the effectiveness of bioslurry reactors for
the degradation  of  wood preserving  wastes was  a  soil  from the
Burlington Northern NPL site in Brainerd, Minnesota.   The overall
results  of the  soil  treatment are presented in a  paper titled
"Slurry Reactor Bioremediation of  Soil-Bound  Polycyclic Aromatic
Hyrocarbons" by Alan Jones, Madonna Brinkmann,  and William Mahaffey
of Ecova Corporation.

     Air  sampling  was  conducted  to  characterize  the  off-gases
emitted from the bioreactors during the operations and to determine
organic constituent loss through volatilization.


     All five reactors were vented through stainless steel piping
into  a  manifold  system before  carbon filtration  and  eventual
exhausting to the outside air.  The air monitoring was conducted at
a point prior to the collective mainfold to obtain emissions from
two individual reactors.

     Two sampling trains were  constructed  to  collect samples for
volatile   and  semivolatile organics.   Volatile   organics  were
collected  in a SUMMA passivated  canister,  and semivolatiles were
collected  in XAD-2  resin tubes.   The  canisters and XAD-2 resin
tubes  were  installed in   the  venting  systems  for the  tested

     Four consectutive sets of  samples were collected from each of
the two  tested  reactors  during the first week of  operation. Two
sets of samples were collected during weeks  2 through 5, and one

 set  of  samples  was  collected during weeks  6,  7,  and  9.

     The air sampling program measured semivolatile,  volatile, and
 total hydrocarbons during the first nine weeks'of treatment.  Total
 Hydrocarbons   (THC)   as  methane  was  determined   according  to
 procedures  in U.S.  EPA Method  25A.   This sampling  was conducted
 continuously  at the main exhaust line for the first five days of
 operation.  Sampling for volatiles  (by modified  Method TO14)  and
 semivolatiles (by modified Method TO13) was conducted periodically
 during  the  first nine weeks  of  operation.

     The   background  ambient  air  showed   THC
averaging  3ppm on a dry basis.  During the charging
THC  emissions   gradually  increased  ;with  peak
averaging  390 ppm or 0.014 Ib/hr   from  17:51  to
1991.  A  table   will be  presented  showing the
emission rates,  and flow rates used to calculate
data are reported as methane because it was used as
gas during the sampling.
 of the reactors'
18:00 oh May 8,
emissions.  All
 the ceil ibration
     The emissions of THC dropped to 0.007 Ib/hr in a little over
6 hours, and  to  0.00176  Ib/hr in,just 24 hours.  Within 48 hours
the  THC emissions were  down  to  less than  0.0003 Ib/hr  and by
72hours were  less than 0.0002  Ib/hr.

     Semivolatile polynuclear aromatics  were detected during the
first  four  days of operation  with  napthalene  found at  8600
ug/sample, 2-methylnaphthalene at 1500ug/sample,and acenahpthene,
fluorene,  phenanthrene,  and  anthracene  going in  order from 703'
ug/sample to 23 ug/sample.   After four days all  samples were below
15ug/sample.  By day  3 the most volatile compounds,  naphthalene and
2-methylnaphthalene had already declined to less than 20 ug/sample.

     The  volatile organics  found  in greatest abundance  were:
xylene, toluene,  ethylbenzene; benzene, and styrene. Table 1 shows
the  results  of the  first  4  days  of measurement  of  12 volatile
compounds. The  samples  again show that  themajority  of emissions
occurred during  the first  few days  of  operation of  the  slurry


     It has often been stated that liquid aerated biotreatment of
hazardous compounds should be avoided because of the potential for
air pollution during the treatment.  The testing of air emissions
during this project shows that the major emissions are during the
charging of the  vessels  and a small amount  may continue for the
first few days.   The  problem of air emissions during charging of a
reactor can be similar or even greater  in charging incinerators or
other non-biological treatment units.

     The levels of both semivolatile and volatile organics found in
the air  emissions  of the  bioreactors dropped back to near  the
background level within four days.  Emission control systems can be
devised for operation of bioslurry reactors,  but  the cost benefit
may be  low when there  are no  major concentrations of  volatile
compounds present in the waste.   The microbes are quite efficient
in capturing and using most of the semivolatile compounds that can
be biodegraded.
TABLE 1.  Volatile Organic Emissions

carbon disulfide
methylene chloride
1,1, 1-trichloroethane
ethy Iben z ene
m- and/ or p-xylene

_ •


Day 4


               Michael L. Taylor, Majid A. Dosani, John A. Wentz, and Avinash N. Patkar
                                         IT Corporation
                                      11499 Chester Road
                                     Cincinnati, Ohio 45246
                                   Telephone: (513) 782-4700

                                        Naomi P. Barkley
                              U.S. Environmental Protection Agency
                              Risk Reduction Engineering Laboratory
                                     Cincinnati, Ohio 45268
                                   Telephone: (513) 569-7854


        In conjunction with promulgating Land Ban Disposal Regulations, the United States Environmental
Protection Agency (EPA) published (Federal Register, May 30,1991) an Advanced Notice of Proposed Rule
Making (ANPR) In which definitions for debris and contaminated debris were suggested as quoted below:

        Debris means solid material that: (1) has been originally manufactured or processed, except for
        solids that are listed wastes or can be identified as being residues from treatment of wastes and/or
        wastewaters, or air pollution control devices; or (2) is plant and animal matter; or (3) is natural
        geologic material exceeding a 9.5 mm sieve size including gravel, cobbles, and boulders (sizes as
        classified by the U.S. Soil Conservation Service), or is a mixture of such materials with soil or solid
        waste materials, such as liquids or sludges, and is inseparable by simple mechanical removal

        Contaminated Debris means debris which contains RCRA hazardous waste(s) listed in 40 CFR
        Part 261, Subpart D, or debris which otherwise exhibits one or more characteristics of a hazardous
        waste (as a result of contamination) as defined in 40 CFR Part 261, Subpart C.

        The ANPR also contains suggested techniques for decontaminating debris prior to disposal.  The
options listed include high pressure washing based, to a large  extent, on work performed by EPA/RREL.
This paper gives an overview of the development and assessment of high pressure washing technology
and presents an update on EPA's efforts to develop a full scale, semi-automatic, debris washing system


        Since 1987,  IT Environmental Programs Inc. (ITEP, a subsidiary of International Technology
Corporation) in conjunction with EPA/RREL in Cincinnati, Ohio, have been developing and conducting
bench scale and pilot scale testing of a transportable debris washing system which can be used on-site for
the decontamination of debris (1).

        During the initial phase of the debris decontamination project, a series of bench scale tests were
performed in the laboratory to assess the ability of the system to remove contaminants from debris and to
facilitate selection of the most efficient surfactant solution. Five nonionic, non-toxic, low foaming,
surfactant solutions (BG-5, MC-2000,  LF-330,  BB-100, and L-422)3 were selected for an experimental
evaluation to determine their capacity to solubilize and remove contaminants from the surfaces of
corroded steel pieces. The pieces of corroded steel were coated with a heavy grease mixture prepared in
   Manufacturers of these surfactants are: BB-ldO, Bowden Industries, Huntsville, AL; BG-5, Modern
   Chemical, Jacksonville, AR; MC-2000, Alcolac, Baltimore, MD; LF-330, GAF Chemicals Corporation,
   Wayne, NJ; and L-422, DuBois Chemicals, Cincinnati, OH.

the laboratory and these pieces of "debris" were placed in a bench scale spray tank on a metal tray and
subjected to a high-pressure spray for each surfactant solution for 15 minutes. At the end of the spray
cycle, the tray was transferred to a second bench scale system, a high-turbulence wash tank, where the
debris was washed for 30 minutes with the same surfactant solution as that used in the spray tank. After
trie wash cycle was completed, the tray was removed from the wash tank and the debris was allowed to air-
dry.  Before and after treatment, surface-wipe samples were obtained from each of the six pieces of
"debris" and were analyzed for oil and grease. Based on the results, BG-5 was selected as the solution
best suited for cleaning grease-laden, metallic debris.


       Based on the results obtained from bench scale studies, a pilot scale debris washing system
(DWS) was designed and constructed. The pilot scale DWS consists of a 300-gallon spray tank, a 300-
gallon wash tank, a surfactant holding tank, a rinse water holding tank, an oil/water separator, and a
solution-treatment system consisting of a diatomaceous earth filter, an activated carbon column, and an
ion-exchange column. The pilot scale DWS was demonstrated at a PCB-contaminated site in Hopkinsville,
Kentucky, and a pesticide-contaminated site in Chickamauga, Georgia.

Demonstration at the Ned Gray PCB Site.  Hopkinsville. KY — This site covers approximately 25 acres.
From 1968 to 1987 a metal reclaiming facility was operated at the site, which involved open burning  of
electrical transformers to recover copper for resale. Approximately 70 to 80 burned-out, PCB-
contaminated transformers were on site, along with large amounts of other materials, including asbestos-
covered pipes, automobiles, and miscellaneous scrap metal. The entire DWS was transported to the
Hopkinsville, Kentucky site on a 48-foot semitrailer and reassembled on a  24 ft x 24 ft concrete pad.  A
temporary enclosure, approximately 25 ft high, was also built on the concrete pad to enclose the DWS
and to protect the equipment and surfactant solution from rain and cold weather.  The demonstration took
place during December 1989 when ambient temperatures at the site during the demonstration ranged
from near 0° to 50°F.

       Prior to the initiation of the cleaning process, the transformer casings, ranging from 5 gallons to
100 gallons in size, were cut into halves with a metal-cutting saw.  A pretreatment sample was obtained
from one half of each of the transformer casings by using a surface wipe technique (2). The transformer
halves we"e placed into a basket and lowered into the spray tank of the DWS, which was equipped with
multiple w, .ter jets that blast loosely adhered contaminants and dirt from the debris. After the spray cycle,
the basket was removed and transferred to the wash tank, where the debris was immersed into a high-
turbulence washing solution.  Each batch of debris was cleaned for a period of  1 hour in the spray tank and
1 hour in the wash tank. During both the spray and wash cycles, a portion of the cleaning solution was
cycled through a closed-bop system in which the oil/PCB-contaminated cleaning solution was passed
through an oil/water separator, and the clean oil-free solution was then recycled into the DWS. After the
wash cycle, the basket containing the debris was returned to the spray tank, where it was rinsed with fresh
water. Upon completion of the cleaning process, posttreatment wipe samples were obtained from each of
the transformer pieces to assess the residual levels of PCBs. The before-treatment concentrations
ranged from 0.1 to 98 u.g/100 cm2. The posttreatment analyses showed that all the cleaned transformers
had a PCB concentration lower than the acceptable level of 10 u.g/100 cm2.

       After treatment of all transformers at the site, the spent surfactant  solution and the rinse water
were neutralized to a pH of approximately 8 by using concentrated sulfuric acid and were treated in the
water treatment system.The before- and after-treatment water samples were collected and analyzed for
PCBs and selected metals (cadmium, copper, chromium, lead, nickel, and arsenic).

       The PCB concentration in the water was reduced by the treatment system to below the detection
limit  of 0.1 u.g/L.  The concentrations of each of the selected metals (except arsenic) were reduced to the
allowable discharge levels set by the city of Hopkinsville for discharge into  the sanitary sewer.  Upon
receipt of the analytical results of the water, the treated water, which was stored in the holding tank, was
pumped into a plastic-covered, 10,000-yd3 pile of contaminated soil at the site. During this site cleanup,
75 transformers were cleaned in the DWS. All of these transformers were considered to be free of PCB
contamination and were sold to a scrap smelter.

Demonstration at the Shaver's Farm Srte. Chickamauga. GA - The second demonstration of the DWS was
conducted at a drum disposal site in August 1990. Fifty-five gallon drums containing varying amounts of a
herbicide, Dicamba (2-methoxy-3,6-dichlorobenkoic acid), and benzonitrile, a precursor in the
manufacture of Dicamba, were buried on this 5-acre site.  An estimated 12,000 drums containing solid and
liquid chemical residues from the manufacture of Dicamba were buried there during August 1973 to
January 1974. EPA Region IV had excavated more than 4000 drums from one location on the site when
this demonstration occurred. The pilot scale DWS and the steel-framed temporary enclosure used
previously at the Hopkinsville,  Kentucky Site were transported to this site in a 48-foot semitrailer and
assembled on a 24 ft x 24 ft concrete pad. Ambient temperature at the site during the demonstration
ranged from 75 to 105°F.                                                                  .

       Prior to treatment in the DWS, the 55-galIon, pesticide-contaminated, empty drums were sawed
into four sections.  Pretreatment surface-wipe samples were obtained from each section.  The drum
pieces were placed in the-spray tank of the DWS for 1 hour of surfactant spraying, then placed in the wash
tank for an additional hour of surfactant washing, followed by 30 minutes of water rinsing in the spray tank.
The drum pieces were then allowed to air-dry before posttreatment surface-wipe samples were obtained.
Ten batches of one to two drums per batch were treated during this demonstration. Pretreatment
concentrations of benzonitrile in surface-wipe samples ranged from 8 to 47,000 u.g/100 crn2 and
averaged 4556 |ig/100 cm2.  Posttreatment levels of benzonitrile ranged from below detection limit to
117 u.g/100 cm2 and averaged  10 uxj/100 cm2.  Pretreatment Dicamba values ranged from below
detection limit to 180 u.g/100 cm2 and averaged 23 u.g/100 cm2, whereas posttreatment concentrations
ranged from below detection limit to 5.2 u.g/100 Cm2 and averaged 1 u.g/100 cm2. The detection  limit for
wipe samples for dicamba and  benzonitrile was 5 ug/100 cm2.

       Upon completion of the treatment, the spent surfactant solution and rinse water were treated in
the water treatment system.  The before- and after-treatment water samples were collected and analyzed
(in duplicate) for benzonitrile  and Dicamba. The concentration of benzonitrile in the pretreatment water
samples was 250 and 400 u.g/L, and the posttreatment concentration was below the detection limit of 5
u,g/L The concentration of Dicamba in the pretreatment samples was 6800 and 6500 u.g/L, and the
posttreatment concentration was estimated to be less than or equal to 630 ug/L (value estimated due to
matrix interferences). Since the concentration of Dicamba in the posttreated water sample was possibly as
high as 630 u7L, the treated water stored in the polyethylene holding tank was pumped into an onsite
water-treatment system for further treatment by  EPA. Although the concentration of Dicarnba in
posttreatment water was ;n estimated value, it was decided to send the water to the onsite water-
treatment system prior to discharge as a precautionary measure.

       The test equipment was decontaminated with a high-pressure wash. The wash water generated
during this decontamination was collected and pumped into the onsite water-treatment system.  The
system and the enclosure were disassembled and transported back to Cincinnati in a semitrailer.


       The extensive experience gained under actual field conditions with the pilot scale DWS lead to
the following conclusions regarding the technology:  1) the desired  results were obtained using  the pilot
scale DWS - a marked reduction of organic contaminants on actual metallic debris from CERCLA sites was
achieved; 2) the generation of large volumes of contaminated waste water was avoided  by employing a
process water filtration  system  which operates concurrently with the debris cleaning process; and 3) the
pilot scale system as constructed is mechanically reliable and proved to be very rugged and amenable to
being transported from site to site. Thus the field studies convincingly demonstrated that the DWS
technology has definite promise for addressing the problem of decontaminating metallic debris at
hazardous waste sites. In addition, important information was also gained during these field
demonstrations which indicate  areas where improvements in the full scale system design could be made
and these are summarized in the following paragraphs.

       The pilot scale system is not a high throughput device and extensive manual handling of debris is
required. Due to the relatively small size of the spray and wash tanks debris larger than approximately
30" x 15" x 30" must be cut to size.  Debris must be manually placed into a basket which is lifted using a
fork-lift and then lowered into the spray tank.  The efficiency of the spraying treatment is limited by the fact
that the wire mesh on the sides of the basket interferes with the spray which emerges from nozzles on the
sides of the spray tank. It was determined that during the one hour spray cycle the best results were
obtained when the spray cycle was momentarily interrupted and the debris was manually repositioned to
enhance contact between the debris surfaces and the spray. The spray intensity was found to be
incapable of removing all of the heavy clay deposits from surfaces of drums excavated in Chickamauga.
As indicated in the above discussion, it is clear that the overall pilot scale process, although generally very
effective for removing hazardous contaminants, is labor intensive.

       When approaching the design of the full scale system the following goals were established:
1) the manual handling of debris is to be kept to a minimum, if not eliminated; 2) the overall throughput of
debris/day is to be markedly increased  (on the order of ten-fold) while not diminishing the effectiveness of
the process; 3) the usage of water is to  be increased somewhat, however recycling of process water to
minimize generation of wastewater is essential; 4) the full scale system should be mounted on one or two
normal-sized semitrailers which require no special permits; 5) the system is to be rugged enough to be
transported from site to site with minimal time and costs for mobilization/demobilization; 6) the system is to
include appropriate features to ensure the safety of workers operating the system and to ensure
containment of emissions potentially harmful to the environment. In an effort to address the goals for the
full scale DWS the following features have been incorporated into the design.  A schematic representation
of the full scale system is shown in Figure 1.

       The unit operations will entail initially loading a heavy duty basket with approximately two tons of
debris (typically metallic debris) which will then be lifted by means of a crane and placed in a 3000 gallon
tank. An innovative system will permit the debris to be directly impacted by high intensity detergent spray
while the debris is subjected to a tumbling action. In addition to the spray/tumbling phase, the debris will
be cleaned using a wash cycle in which the debris is immersed in cleaning solution and then a final
spray/rinse will be utilized to remove residual contaminated liquid from the surfaces of the debris.  The
contaminated liquids (detergent solution,  rinse solution) will be continuously treated using a transportable
process water treatment system which will include various treatment modules which will be implemented to
decontaminate the process water. In th?s fashion, the quantity of process water generated during the
debris cleaning process will be significar ly minimized.  The full scale DWS will be mounted on two
semitrailers. Site preparation will be minimal and is expected to entail leveling and placing of gravel or
crushed stone on which the trailers will  be parked.


1)     Technology Evaluation Report: Design and Development of a Pilot Scale Debris
        Decontamination System, U.S. Environmental Protection Agency. EPA 540/5-91-006a,
       August 1991.

2)      Field Manual for Grid Sampling of PCB Spill Sites to Verify Cleanup, U. S. Environmental
        Protection Agency, EPA 560/5-86/017, May 1986.


       This research was funded in its entirety by the United States Environmental Protection Agency's
Risk Reduction Engineering Laboratory under Contract No. 68-03-3413.  Naomi Barkley is the Technical
Project Monitor.

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                          TREATMENT OF HAZARDOUS AND TOXIC

                                       David LaMonica
                                  Rochem Separation Systems
                              3904 Del Amo Boulevard, Suite 801
                                   Torrance, California 90503
                                       (310) 370-3160

       Rochem Separation Systems, established in 1990 as a subsidiary of the international Rochem
Group, has advanced the treatment of hazardous and toxic liquids with its unique, patented Disc Tube
technology. Developed in 1987 at Rochem's design arid production facilities in Hamburg, Germany, the
,Disc Tube technology is a series of membrane modules that greatly reduce the problems that hamper the
effectiveness of other treatment technologies (i.e. fouling, scaling, cost, etc.). Applications of the Disc
Tube technology include reverse osmosis and ultrafiltration. Rochem was recently accepted into the
EPA Superfund Site program as a result of  its Disc Tube technology.


       The Rochem Disc Tube is constructed from a series of octagonal membrane cushions separated
by a series of plastic spacer discs. The discs support the membrane cushions but leave an open channel
flow path through the module (see Figure 1). The minimum clearance in the feed water flow path of the
Disc Tube is approximately one millimeter. The flow path through the module is radial, progressing from
the center of one disc to the edge of the cushion. The flow then makes a  180 degree turn and flows
inward over the other side of the membrane cushion. The flow path repeats for each membrane cushion
in the stack. The flow reverses direction every three inches. The turbulence created by the flow reversal
eliminates the concentration polarization, minimizing scaling and fouling while maintaining high energy
efficiency. Also, the Disc Tube operates effectively at increased turbidity and Silt Density Index (SDI)

RESULTS                                                               ,

       Rochem is currently operating its Disc Tube technology in reverse  osmosis (RO) systems at
various hazardous  landfill leachate sites throughout Europe, including one  at Schwabach, Germany. The
RO systems are being used at the sites to treat leachate seeping  into the  ground and contaminating
valuable ground water. The effluent produced from the ieachate treatment  process meets applicable
discharge standards by removing up to 99% of all dissolved solids  and BOD (see Table  1).


       The use of membranes for the reduction of difficult hazardous liquids was not economically
feasible prior to the advent of Rochem's Disc Tube concept. Due to the Disc Tube's unique design,
liquids that traditionally inhibit the use of membranes as a result of scale formation and biological fouling

are handled efficiently. In addition, by utilizing a combination of membrane systems to treat hazardous
liquids such as multi-component waste found at hazardous landfills, cost effective and efficient
treatment can be achieved. The most significant advantage this technology has over single membrane
systems is that all major contaminants are reduced to within prescribed regulatory limits. Also,
membrane performance is improved by selecting membranes chemically compatible with the waste to be
                                       FIGURE 1

                             DISC TUBE MEMBRANE MODULE
                              HYDRAULIC FLOW SCHEMATIC
                                            PEHMEATE   3R1NE
                                                HYDRAULIC DISC

                                                 MEMBRANE CUSHION
                                     TENSION ROD

                       TABLE 1

Parameter Untreated Leachate
El Conduct (u,s/cm)
PH Value (mg/l)
COD (mg02/l)
BOD (mgO2/l)
TOC (mg/l)
Hydrocarbons (mg/l)
Sulfate (mg/l)
Ammonium (mg/l)
Arsenic (mg/l)
Cyanide (mg/l)
Vanadium (mg/l)
Second Stage Permeate Rejection


                             THE SITE DEMONSTRATION
                                     OF THE
                                 Laurel Staley
                               Chemical Engineer
                  Superfund Technology Demonstration Division
                     Risk Reduction Engineering Laboratory
                      U.S.  Environmental  Protection Agency
                            Cincinnati, Ohio  45268
                                 (513)  569-7863
       Plasma is  highly ionized gas  that  contains  equal  numbers  of positively
 and  negatively charged particles.   Plasmas  can  be created  by  passing  gas
 through  an  electrical  discharge and thereby ionizing  it.   The Plasma
 Centrifugal  Furnace  (PCF),  developed by  Retech  Inc. of  Ukiah, California,  uses
 plasma generated by  a  transferred-arc torch to  vitrify  contaminated soil.  In
 this system,  soil  contaminated with .organic chemicals and  metals  is fed to the
 rotating PCF vessel.   The plasma torch is used  to heat  and melt the soil  at a
 temperature  of approximately  3000°F.,  As the soil melts, organic contamination
 is driven into the gas phase  which  is at an average temperature of 2000°F.
 Organic  contamination  is thermally  destroyed at these temperatures.   Exhaust
 gas  from the PCF is  treated downstream to remove  any unburned hydrocarbons,
 acid gas and particulate.   Melted soil is intermittently discharged from  the
 PCF  and  allowed  to air cool into a  glass-like solid mass.


      The PCF  was demonstrated  as part of the EPA's Superfund  Innovative
 Technology Evaluation  (SITE)  program in July 1991  at the U.S. Department  of
 Energy's Magnetohydrodynamics  Component Development and Integration Facility
 (CDIF) in Butte, Montana.   During th^ demonstration, the PCF. treated  1440  Ib
 of soil  contaminated with 28000  ppm  zinc oxide, 1,000 ppm  hexachlorobenzene
 and  10%  by weight  No.  2 diesel  oil.   This material was fed to the  PCF at  120
 Ib/hr.   To evaluate the performance  of the  system, the EPA sampled the feed
 and  all  effluent streams from  the process.  On  cooling,  the treated soil
 formed a glass-like matrix.  During  vitrification, organic contamination  in
the  soil  was  volatilized and thermally destroyed.


      Preliminary results from the demonstration indicate that the PCF
effectively immobilized the zinc contamination while thermally destroying the
hexachlorobenzene.  The vitrified soil produced by the PCF did not produce
Teachable quantities of zinc.    In fact, while the feed soil produced leachate

containing 982 mg/L zinc, the vitrified soil  produced leachate that contained
only 0.30 - 0.45 mg/L zinc.  While much of the zinc was volatilized during
vitrification, acid digestion of the slag revealed that it still  contained
between 6000 ppm and 9000 ppm zinc.  Although zinc is not regulated under the
TCLP rule, these results clearly indicate that the PCF was able to immobilize
the zinc that remained in the slag.  The Destruction and Removal  Efficiency
for hexachlorobenzene was greater than 99.99%.  Benzene was the only Products
of Incomplete Combustion detected at significant levels.

      Particulate emissions were 0.374 grains/dscf which exceeds  the RCRA
regulatory limit of 0.08 grains/dscf.  Emissions of NO  averaged  5000  ppm.
Because the flowrate of the stack gas is very low in the PCF,   NOX emissions
did not exceed regulatory limits.  These emissions remain a concern, however.
In full-scale PCF applications,
NO  and  additional  particulate  control  may be

      The results of the SITE demonstration of the Retech Plasma Centrifugal
Furnace indicate that it may be a practical vitrification technology.
Additional particulate and NOX control  may be necessary,  but  such  control  is
readily available and should not prevent this technology from being used at
sites where it is otherwise applicable.


                     SITE  DEMONSTRATION OF THE

                        Paul R. de Percin
           Superfund Technology Demonstration Division
              Risk Reduction Engineering Laboratory
                     Cincinnati, Ohio  45268

     In 1986, the U.S. Environmental Protection Agency  (USEPA)
established the Superfund Innovative Technology Evaluation  (SITE)
program to promote the development and use of innovative
technologies to clean up Superfund sites.  A SITE program field
demonstration was performed on the SoilTech Anaerobic Thermal
Processor (ATP) at the Wide Beach Development site in Brant, New
York during May 1991.  This technology is designed to thermally
desorb organic contaminants such as polychlorinated biphenyls
(PCBs) from soils and sludges.  During this demonstration, the
ATP was used in conjunction with dehalogenation using alkaline
polyethylene glycol  (APEG) reagents to chemically destroy PCB


     The SoilTech ATP is an innovative, indirectly-heated rotary
kiln system, using a physical separation process that thermally
desorbs organics from soils and sludges.   Dehalogenation is
accomplished by spraying the contaminated soil with a diesel fuel
and oil mixture which acts as a carrier for the APEG.  The kiln
provides intimate soil and reagent mixing combined with elevated
temperature and residence time to accelerate the APEG
dechlorination reactions.

     The ATP kiln  is  innovative because it has four distinct
zones.  The first  section is the preheat zone where the
contaminated feed  temperature is elevated to about 500°F.  The  -
next section is the retort zone where the soil is heated to
900°F,  either volatilizing or coking the hydrocarbons under
anaerobic conditions.  The third section is the combustion zone
where the kiln is  heated and non-condensable hydrocarbons are
destroyed.  The last  section is the cooling zone in which the
soil is cooled by  heating the preheat zone.  Sand seals allow-the
different zones to have separate operating conditions.       ,

     The unit is designed to handle 10 to 15 tons per hour 'of
solids containing  up  to 20 percent moisture and 10 percent
hydrocarbon content.  Wastes with greater than 20 percent
moisture require dewatering to improve process economics and
wastes with greater than 10 percent hydrocarbon content may
require multiple passes through the unit.

     During the remediation, the contaminated soils were
excavated from yards  and roadways, and staged in the contaminated
feed storage area.  Prior to entering the processor, contaminated
soil passed through a grinder.


     Between 1968  and 1978, about 40,950 gallons of waste oil,
some contaminated with PCBs, was applied to area roadways for
dust control.  In  1980, a sanitary sewerline was installed, and
PCB-contaminated soils were excavated and used as fill in several
residences.  As a  result of these activities, approximeitely
42,000 tons of soil were contaminated with PCBs.  Conteimination
levels in these soils ranged from the low tens of parts per
million (ppm) to over 5,000 ppm.


     The SITE technology demonstration had the following
obj ectives:

     1)    Assess the  technology's ability to remove PCBs and
          other organic contaminants from the soil,

     2)    Determine whether polychlorinated debenzo-p-dioxins
          (PCDD)  or polychlorinated dibenzofurans (PCDF)  are
          produced in the system,

     3)    Document the operating conditions of the SoilTech ATP,

     4)    Determine capital and operating costs of the ATP


     For the SITE demonstration, three tests were conducted
during full-scale remediation while the ATP was operated under
typical operating conditions.  Each test run consisted of 5.5
hours of solids and liquids sampling and 5 hours of concurrent
stack sampling.  The solid and liquid samples included
contaminated feed soil, treated soil, combined flue gas cyclone
fines and baghouse dust, preheat vapor cyclone fines, scrubber
liquor, condensed water (before and after treatment), vapor
scrubber oil, and preheat oil.  In addition to stack gases, the
non-condensable preheat and retort off-gases also were sampled
during each run.  Laboratory analyses included analyses of solid,
liquid and stack gas for PCBs, dioxins/furans, volatile organic
compounds (VOCs), and semivolatile organic compounds (SVOCs).
Extractable organic and inorganic chlorides were also analyzed in
an attempt to trace the fate of chlorine throughout the system.
A variety of other general chemistry and macronutrient analyses
were performed to characterize the feed and treated soils.

     The unit was operated at an average 6.3 tons per hour during
the three runs.  Other parameters, such as kiln temperature,
stack flow rates, etc., were maintained at essentially constant

     Key findings from the Wide Beach SITE demonstration are:

     1)    The SoilTech ATP removed PCBs from the contaminated
          soil to levels below the EPA-required cleanup
          concentration of 2 ppm.   The highest average treated
          soil PCB concentration was 0.073 ppm.


Dioxins and furans did not seem to be created.

No_major operational problems affecting the ATP's
ability to treat the contaminated soil were observed.

The average stack gas emissions were:
                    0.362     gr/dscf  (7% O2)
                    0.054          Ib/hr
                    3.87 x 10'4     Ib/hr
                    1.37 x 10"7
No VOC and SVOC degradation products were found in the

                              EXTENDED ABSTRACT
                                       for the
           US EPA Risk Reduction Engineering Laboratory Research Symposium
                                   Cincinnati, OH                              ,
                                   April 14-16,1992                                  '


                                    JimOsborn                                     "
                               Field Robotics Center
                             Carnegie Mellon University                 .   ,   .
                                Pittsburgh, PA 15213                            '   '

   Non-invasive imaging of the underground is an essential component of hazardous waste site
investigations, yet, despite advances in sensjor technology, high quality maps of the subsurface
are difficult to obtain. Subsurface mapping depends on the spatial correlation of individual
sensor measurements taken at multiple locations. Current manual data collection techniques,
however, are subOptimal for precisely positioning  subsurface imaging sensors and 
 obstacles while maximizing coverage of the surface.

   At each point in sampling grid, a pulse is transmitted into the ground and the energy
 reflected to the receiving antenna is recorded, digitized and pre-processed to remove pulse
 transmission effects and noise. Three dimensional data arrays are then formed using the position
 information associated with the records. The waveform recorded at each grid point is actually a
 composite of all radar reflections within the antenna's conical beam pattern due to the poor
 focusing of the  GPR antenna. However, since the spacing between surface grid  points is
 accurately measured, we are able to correlate all of the measurements and synthetically focus the
 antenna. Vertical-and horizontal sections of the resulting subsurface map are then displayed as
 color or gray-scale images and enhanced further with several filtering and feature detection

   SIR is an example of an emerging class of robots dedicated to the solution of hazardous waste
 problems. The spatially correlated information that Site Investigation Robot generates will be
 used to more effectively conduct the costly phase of site remediation. This, along with reduction
of human exposure will ultimately lower the expense of site cleanups. This  project is a
preliminary step towards broader capabilities in automated waste site investigations, such as
acquisition of a wider variety of data, environmental sampling, centralized site databasing, and
computer-aided site modeling.

Figure 1. The Site Investigation Robot prototype


                                         Theodore S. Jordan
                                 Metallurgical Engineering Department
                           Montana College of Mineral Science & Technology
                                        Butte, Montana 59701
      Throughout history, both the mining of ores and the extraction of metals from them has been guided
  by economic considerations.  Thus, the miner took those ores that were easiest to mine and the
  processor extracted those values that came out readily. Processing focused on improving metal
.- reqpyery to the extent that the cost of increased yields was more than.conipensated by,the values
  recovered, but those minerals whose extraction cost exceeded their value were left behind.  The result
  has been the accumulation of thousands of tons of partially depleted mineral resources, generally known
  as mil) tailings.                                                            .-;",     ,,

      Over one hundred years of extensive mining and milling operations has left the area of Butte,
  Montana, 'The Richest Hill on  Earth", with millions of tons of tailings containing varying amounts of
  metallic  minerals.  The initial mode of occurrence of these minerals was in the form of sulfides, the
  primary  source of base metals such as copper.lead, zinc, nickel, etc. Substantial amounts of such
  minerals remain in the tailings impoundments. Through exposure tolthe atmpspherei the elements and
  bacterial action, the sulfides, which are relatively insoluble in water, oxidize to soluble sulfates, creating
  acidic drainage, laden with heavy metals and harmful to plant, animal and aquatic life.  The watershed
  from this area, known as the Clark Fork Drainage, comprises the largest collection of Superfund Sites in
  the United States.                                                             ;   r;

     Naturally, extraction technologies have improved over the course of Butte's mining history, while ore
  grades have progressively diminished.  Thus, the oldest tailings are those containing the highest content
  of sulfides.  Sometimes overlain by more recently-produced and cleaner tailings, they still produce acidic
  effluent.               ,        ,      .           :                ,      •  ,       :       ,  :

     The work undertaken in this project  is directed toward developing means to reprocess old tailings in
  order to  remove a substantial percentage of the acid producers and, hopefully, to recover sufficient
  mineral values to offset some of the cost of removal and refreatment.

     The most modern method  of separating sulfide minerals is froth flotation (hereinafter referred to
  simply as flotation), wherein mineral surfaces are selectively rendered water repellent by subjection to a
  suitably controlled chemical environment within an aqueous slurry.  Prior to the advent of flotation early
  in the 20th century, the primary method  of separating sulfides from associated waste minerals was by
  gravity concentration, which is quite sensitive to particle size. While the lower particle size that can be
  separated by gravity concentration is in the range of 300 micrometers, flotation reduced the lower size
  limit to about 50 micrometers.  This development was especially significant in the processing of Butte
  ores, since the values in them are concentrated in the finer size fractions.

     The Butte area thus contains two general types of tailings, those from older gravity operations and
 more recently produced flotation tailings. As would be expected, the flotation tailings have been ground
 to a finer size and contain less mineral values than do the gravity tailings. Thus, the older gravity tailings
 are the more obvious target for remediation through removal of sulfides left behind by earlier processors,
 but retreatment of either type of tailing would be enhanced by the development of technology that would
 recover particles finer  in size than those recoverable by flotation.

    Tailings from the old Colorado Mill, a Superfund site containing about 250,000 cubic yards of gravity
concentration tailings, was the initial target of this project.  Preliminary tests indicated that this material
was an ideal  candidate for retreatment through the Air-Sparged-Hydrocyclone (ASH), to be described
later.  A proposal to evaluate the ASH with Colorado tailings was submitted to the U. S. Environmental
Protection Agency (EPA),  but shortly after its acceptance, the Potentially Responsible Party (PRP) for
Colorado Mill tailings withdrew permission for removal of a quantity of the material for the work.
Subsequently, a more recent tailing, resulting from  a flotation operation, was obtained and tested.


    Rotation  is conventionally carried out in stirred tank reactors in which ground mineral particles are
held in suspension in water, which disperses the necessary chemical reagents and to which air is added
and fractionated into fine bubbles by a rotor/ stator arrangement. In the agitated slurry, particles and
bubbles collide, with water repellent particles adhering to bubbles when collision takes  place. The
bubble/particle agglomerate levitates to the slurry surface and overflows to a suitable container, thus
separating water repellant from water wettable particles. Poor flotation recovery of small  particles is
thought to result from low probability of collision due to the reduced inertia attendant with light weight.

    Most of the attempts to develop more effective means of flotation have focused on  flotation machine
design. One such device  is the Air-Sparged  Hydrocyclone (ASH), which was developed! by Dr. J. D.
Miller of the University of Utah in the 1980's.  The ASH, diagrammed in Figure 1, increases the
probability of particle/bubble collision in two ways:  1)  particles enter the ASH  at a high tangential
velocity and,  2) the porous inner wall of the ASH admits a great number of fine  air bubbles in a swirling
layer in line of contact with the particle stream.  As in conventional hydrocyclones, lighter particles exit
upwards through the vortex finder and heavier particles leave through the bottom of the device.  In the
ASH, the lighter particles are the particle/bubble agglomerates.
                                            UNDERFLOW CONTROL SLEEVE

                                                         UNDERFLOW DISC
                                         DISC WtTH DESIRED DIAMETER IS INSERTED
                                         TO CONTROLTHE UNDERFLOW
                                Figure 1. Air-Sparged Hydrocyclone

  The ASH is licensed in Montana to Hydroprocessing and Mining of Montana (HPM), who have set up
a,pilot plant for its evaluation.


    Chemical analyses of the metal content of various size fractions of a randomly-selected sample of
Colorado Mill tailings, before and after size reduction by grinding, are presented in Table 1.

Tyler Mesh
As Received
—35 + 48
-48 + 65
-65 + 100
-100 + 150
-150 + 200
Calculated Head
After Grind
-35 + 48
-48 + 65
-65 + 100
-100 + 150
-150 + 200
Calculated Head
Weight %




Assay. %

Distribution. %







Inspection of the table points out the tendency of the metal-bearing minerals to report in the finer size

    Ground material was then passed through the ASH repeatedly to see if repeated treatment5
("scavenging") would bring about progressive flotation of a number of potentially toxic elements.
Resulting data are summarized in Table 2, in which UF signifies the underflow or rejected portion and
OF the overflow or concentrate. (Underflow from the first cycle becomes feed to the second cycle and
underflow from the second cycle is feed to the third cycle.)  Since concentrate is removed after each
test, feed to the succeeding cycle is lower in grade, which accounts for the progressive decrease in both

underflow and overflow grade.  In commercial milling operations, it is normal practice to scavenge the
ore stream to the extent required to give a desired recovery. The lower grade concentrates are returned
to preceding process cycles in order to achieve acceptable concentrate grades.

                                      THROUGH THE ASH
Analysis in Milligrams per Kilogram (ppm) in Solids
< 5.0
< 0.2
< 5.0
< .002
< 0.2
< 5.0
< .002
< 0.2
< 5.0
< 0.2
OF #2
< 5.0
< 0.2

OF #3
< 5.0
< 0.2
The above results led to submission of the proposal to EPA. Due to the refusal of the PRP to supply
sufficient material for complete testing, a sample of about 28 tons of tailings from the defunct Marget
Ann mill was obtained from New Butte Mining Company, who are interested in ASH technology and had
earlier cooperated with HPM in testwork on dump ore from the Butte area.  The Marget mill operated
briefly In the 1950's and appears to have been a technical  success but an economic failure.

   Preliminary examination showed the material to be quite low in metal values and somewhat
contaminated with organic matter.  It was also found that,  like most local tailings, metal content
increased with decreasing particle size. This is illustrated in Table 3.

   Three factorial design experiments at different levels of grind, collector and activator showed only
minor concentration of lead or zinc by flotation in a conventional laboratory machine. Tests in the ASH
pilot plant were carried out under various conditions, since success with this difficult material would
Indeed demonstrate the utility  of the ASH  in the flotation of fine mineral particles.
        a                                 :
   Nine campaigns were completed with,results similar to those obtained from the conventional
flotation machine. The low grade of the starting material made accurate analysis difficult and material
accounting was poor. Work on Marget Ann tailings was terminated after analysis of data from the ninth
run and remaining material and test products were returned to the tailings site.

Tyler Mesh Weiaht %

+ 100 7.0
-100 + 200 12.6
-200 (Dry) 3.0
-200 (Wet) 77.4
Calculated Head Assay

, , .042
Assav. %
Distribution. '



    It is concluded that the Air-Sparged-Hydrocyclone shows promise for recovering sulfide minerals
from materials typified by Colorado Mill tailings but thai each candidate for such treatment must be
evaluated by testing.

    Pilot plant work in the immediate future will focus on the quantity of Colorado Tailing that remained
after the preliminary work that led to submission of the project proposal. If this shows promise, another
tailing sample will be sought.  If results are negative, the project will be terminated.


                            Walter J. Weber, Jr., and Thomas M. Young

                         Department of Civil and Environmental Engineering
                                    The University of Michigan
                                Ann Arbor, Michigan  48109-2125
                                        (313)  763-1464
       Accurate assessment of the extents to which various hydrophobia organic contaminants will sorb
to different types of soils is critical to the development of realistic models of contaminant fate and
transport, as well as to the selection of effective remedial strategies.  Results of field studies show that
hydrophobia organic compounds persist longer and migrate more slowly than predicted by commonly
used ground water transport models, which are predicated on simple linear, reversible, equilibrium
sorption phenomena. The goals of this research are to develop: 1) an improved model of complex
sorption behavior in soils and, 2) a protocol which can be employed as a basis for the more realistic
selection of appropriate transport  models  and remedial technologies for contaminated subsurface sites.


       Three general classes of  binding  interactions between contaminants and soils can be identified
(1). Chemical sorption occurs when a bond, having all of the characteristics of a true covalent bond, is
formed between a functional group on the soil surface and the sorbed chemical. A second type of
interaction, which is common for polar solutes, is electrostatic or ionic bonding between the solute and
charged functional groups on the soil surface; an example is the bindjng of calcium ions to a clay.  Non-
polar solutes are typically bound to soils by relatively low energy dipole interactions with functional groups
on the soil surface.  Adsorption of a hydrophobia compound results from the cumulative effect of  these
binding interactions and repulsive interactions between the solute and the solvent that seive to drive
solute molecules out of solution and onto  soil surfaces.

       The wide range of forces  contributing to sorption phenomena results in great variations in binding
energies between particular solutes and soils. Most soils are intrinsically heterogeneous, generally being
comprised of a conglomeration of  various  mineral and organic surface types. The binding strength and
isotherm shape for sorption of a given contaminant on a given soil surface is determined by the
distribution of the energies of individual soil fractions. Uniform distributions of binding energies usually
result in linear isotherms at low surface coverages,  while variations in the binding energies of the various
components comprising a soil will  commonly yield non-linear isotherms (2).

       Sorption of hydrophobia organic contaminants on soils is frequently described by models that are
predicated on the assumptions that 1) soil organic matter is the principal, if not the only, soil fraction
exhibiting significant reactivity and 2) all soil organic matter has similar binding energies for non-polar
organic compounds. Sorption is therefore treated in these models as a linear, reversible process
dominated by weak physical binding reactions.  Several investigators have generalized this concept by
developing correlations that allow the prediction of partition coefficients from the knowledge of a solute's
hydrophobicity and a soil's organic carbon content  (3).

       A number of limitations have been observed in applying these correlations to diverse soil
systems. The correlations generally fail for soils pf  low organic carbon content, such as those typically
found in subsurface environments. Non-linear isotherms have been reported for a number of low organic
carbon subsurface soils (4,5).  The nature of the organic carbon present in the soil has also been shown to
influence the sorption of non-polar organic molecules.  More reduced organic matter, reflected by higher
C/O or H/O ratios, has a higher capacity to adsorb organic compounds than more oxidized organic matter
(2,6,7).  Furthermore, the  assumption of local equilibrium between contaminants and soils in ground water
systems has been shown  to be invalid in a number of experiments (1,8). Explanations for non-equilibrium

include extremely slow sorption rates (1,8,9) or hysteretic effects (10).  Consequently, contaminants
present in a soil for an extended time period may be more difficult to desorb than freshly added material
(11). The total effect of the foregoing  limitations is to call into question the accuracy of the microscopic,
linear, reversible, local equilibrium sorption model for despribing macroscopic solute transport in many
subsurface contamination situations.


       Selection of an inappropriate microscopic model of contaminant sorption can lead to significant
macroscopic modeling errors. For example, when a literature correlation developed for high organic
carbon surface soils is used to predict linear partitioning coefficients for low organic content subsurface
soils, the amount of sorption may well be underestimated, and the time required to complete a pump-and-
treat remedial scheme may therefore be far longer than predicted. Problems with literature correlations
can be avoided by conducting laboratory studies to generate isotherms specific to the soil-contaminant
system at a particular site. This method is not without pitfalls,  however. When the data span too small a
range of solution concentrations, isotherm non-linearities may be overlooked. Short equilibration times in
the laboratory may cause hysteresis or aging effects to be missed, resulting in underestimates of true
levels of contaminant binding by soils in the system. In each case the results will be overly optimistic
estimates of the ease of soil remediation. Ideally, the reactivity of each type of soil fraction could be
measured and a soil's binding strength for a contaminant could be calculated by using an appropriate
distributed reactivity model (2). The complexity, immense diversity,  and unknown structure of most soil
organic matter represent great obstacles to obtaining the data needed for routine use of this approach.
Alternatively, a tool might be developed to quantify binding strengths between specific contaminants to
be removed and soil samples from the site in question.


       Supercritical fluid extraction using non-polar gases such as carbon dioxide appears to offer a
reasonable basis for development of such a tool. The  chief advantage in using non-polar supercritical
fluids as extraction solvents lies in their controllable solvent strength and minimal solvent-solute
interactions. The solvent strength of supercritical fluids is directly related to their density, which can be
varied easily by changing the pressure in the extraction vessel.  Moreover, mass transfer is often orders of
magnitude faster in supercritical fluids than in liquid solvents because supercritical fluids have more
favorable diffusivities and viscosities.  Finally, supercritical fluids offer important practical advantages
because they are usually inert, non-toxic and relatively inexpensive.  Efficiencies approaching or
exceeding those of Soxhlet extractions have already been demonstrated for removing several organic
solutes from soil and other solid matrices using supercritical carbon dipxide-cosolvent mixtures. Solutes
studied include polynuclear aromatic hydrocarbons (12,13), polychlorinated biphenyls and DDT (14)

       In order to quantify the binding strength between a contaminant and a soil, non-quantitative
extractions can be performed at different pressures. Successive increases in extraction efficiency with
increasing energy input at higher pressures can then be used to calculate a distribution of binding
energies for the contaminant/soil system of interest. Changes in binding strength with aging of the
contaminant will be measured to develop a model of contaminant aging effects.  Finally, the binding
strengths  measured in the supercritical fluid extraction experiments will be compared with the
effectiveness of remedial schemes for soils including bioremediation, soil washing, and pump-and-treat
methods.  If a correlation  is found, supercritical fluid extraction may be a useful screening tool for
predicting remedial effectiveness.


       Supercritical fluid extraction appears to have great potential  as a new tool for examining the
sorptive behavior of soils based on the results  of studies that have already been conducted in this area.
The need to improve our understanding of these processes is amply demonstrated by the number and
severity of soil and sediment contamination incidents that have been reported and by current difficulties in
modeling the removal of hydrophobia compounds from soils and sediments.  It is our objective that the
research being conducted under this  project will improve our knowledge of the microscopic sorption

mechanisms operative in diverse types of soils and, consequently, increase the accuracy with which
macroscopic transport and remediation of contaminants can be predicted.

ACKNOWLEDGEMENTS                     |

        This work is supported in part under Cooperative Agreement No. 818213 with the U.S.
Environmental Protection Agency. The Project Officer is Dr. John E. Brugger, Releases Control Branch,
Risk Reduction Engineering Laboratory, U.S. EPA, Woodbridge Avenue,  Edison, NJ 08837-3679.


(1)     Weber, W.J., Jr., McGiniey, P.M., and Katz, L.E. Sorption phenomena in subsurface systems:
        concepts, models and effects on contaminant fate and transport. Water Res. 25:499-528,1991.

(2)     Weber, W.J., Jr., McGiniey, P.M., and Katz, L.E. A distributed reactivity model for sorption by soils
        and sediments: conceptual basis and equilibrium assessments. Environ. Sci. Technol. in review,

(3)     Karickhoff, S.W., Brown, D.S., and Scott, T.A. Sorption of hydrophobic pollutants cm natural
        sediments. Water Res. 13:241-248,1979.

(4)     Miller, C.T. and Weber, W.J., Jr. Modeling organic contaminant partitioning in ground water
        systems. Ground Water 22:584-592. 1984.

(5)     Miller, C.T. and Weber, W.J., Jr. Sorption of hydrophobic organic pollutants in saturated soil
        systems. J. Contam. Hydrol.1:243-261,  1986.

(6)     Garbarini, D.R. and Lion, L.W. Influence of the nature of soil organics on the sorption of toluene
        and trichloroethvlene. Environ. Sci. Technol. 20:1263-1269, 1986.

(7)     Grathwohl, P. Influence of organic matter from soils and sediments  from various origins on the
        sorption of some chlorinated aliphatic hydrocarbons: implications on Koc correlations. Environ.
        Sci. Technol. 24:1687-1693. 1990.

(8)     Miller, C.T. and Weber, W.J., Jr. Modeling the sorption of hydrophobic contaminants by aquifer
        materials-ll Column reactor studies. Water Res. 22:465-474,1988.

(9)     Bali, W.P. and Roberts, P.V. Long-term sorption of halogenated organic chemicals by aquifer
        material. 1.Equilibrium. Environ. Sci. Technol. 25:1223-1235,1991.

(10)     Horzempa, L.M. and DiToro, D.M. The extent of reversibility of polychlorinated biphenyl
        adsorption. Water Res. 17(8): 851-859,1983.

(11)     Steinberg, S.M., Pignatello, J.J., and Sawhney, B.L. Persistence of 1,2-dibromoethane in soils:
        entrapment in intraparticle micropores. Environ. Sci. Technol. 21:1201-1208,1987.

(12)     Hawthorne, S.B. and Miller, D.J. Extraction and recovery of polycyclic aromatic hydrocarbons from
        environmental solids using supercritical fluids. Anal. Chem. 59:1705-708.1987.

(13)     Hawthorne, S.B. and Miller, D.J. Extraction and recovery of organic pollutants from environmental
        solids and Tenax-GC using supercritical CO2- J. Chrom. Sci. 24:258-263,1990.

(14)     Brady, B.O., Kao, C.C., Dooley, K.M., Knopf, F.C., and Gambrell, R.P. Supercritical extraction of
       toxic oraanics from soils. Ind. Eno:. Chem. Res. 26:261-268,1987.


       Henry H. Tabak, U.S. EPA,  RREL,  Cincinnati, OH 45268  (513) 569-7681
 Rakesh Govind, Chao Gao, In-soo  Kim,  Lei Lai,  Department of Chemical Engineering,
                  University of Cincinnati, OH 45221 (513) 556-2666
       As  EPA  begins to remediate  Superfund  sites  using  permanent  treatment
technologies, such as  bioremediation, a  fundamental understanding of the kinetics
and the factors  that control  the rate of bioremediation will be required (1).  Biological
treatment  technologies  hold considerable promise for safe,  economical,  on-site
treatment of toxic wastes (2).  A   variety of biological treatment systems  designed  to
degrade  or  detoxify environmental contaminants are currently being developed   and
marketed.  Knowledge of the kinetics of biodegradation  is essential to the evaluation
of the persistence  of  most organic  pollutants in  soil  (3,4).   Furthermore, measurement
of biodegradation kinetics can provide useful  insights into the  favorable range of the
important environmental  parameters  for improvement of the microbiological activity and
consequently the enhancement of  contaminant biodegradation.

       A major  effort  is  currently underway to clean up aquifers  and soils  that are
contaminated by  organic chemicals, which has  generated  increased interest in the
development  of in situ bioremediation technologies.   Although  considerable data
exists  for rates  of biodegradation  in aquatic environments, there  is little information on
biodegradation  kinetics  in soil  matrices, where irreversible  binding to the  soil phase
may limit  the  chemicals bioavailability and ultimate degradation.   Knowledge  on
biodegradation kinetics in soil environments can facilitate decisions on the  efficacy  of
in situ bioremediation.

       Recently, increased interest  has been  directed towards obtaining quantitative
information on  pollutant sorption equilibria in  soils, since  the physical  state of the
compound  can influence  its  bioavailability.  Information  concerning the availability  of
hydrocarbons sorbed on  soil can be  useful in  choosing  the appropriate technology  to
treat subsurface contamination by gasoline, which  is released to the environment as a
result  of accidental  spills and leaking underground storage tanks.

       The main objective of this  research is  to quantitate  the  bioavailability and
biodegradation  kinetics of  organic  chemicals  in   surface  and  subsurface   soil
environments,  examine  the  effects of soil matrices and  soil  conditioning  (drying,
aging,  compaction),  and develop  a  predictive  model  for biodegradation  kinetics
applicable  to soil systems.
       Four separate  soil microcosm reactors were  designed,  assembled  and installed,
to simulate  contaminated  sites.    Each  microcosm reactor  consisted of  a glass
aquaraium (12  in.x  20  in.x  12  in.) with about 6  in. depth  of  soil.      Undisturbed,
uncontaminated  forest  soil from  Northern  Kentucky  was placed  in  each  microcosm
reactor.  The  reactor was then brought  into the laboratory,  and contaminated with  a
known class  of  compounds.  Initially,  our  study  was  confined  to phenols,  PAHs,

chlorinated phenols, and  aromatic  hydrocarbons.  Nutrients were periodically sprayed
on top of the soil surface, to simulate rainfall.  A known flow rate of carbon dioxide free
air  was  introduced  into the headspace  of  each  microcosm  reactor,  and the  carbon
dioxide concentration  in the  exit gases was carefully monitored.

       Each  microcosm  reactor represents  a  controlled  contaminated  site,  which
eventually will  have  acclimated  microorganisms  for  the  contaminating   organics.
Samples  were taken  from  the  microcosm  reactors  for  measuring  oxygen  uptake
respirometrically,  carbon  dioxide generation kinetics, and  other studies.

       Studies were conducted  with  soil slurry reactors, wherein  the oxygen  uptake
was  monitored respirometrically  (5).   Various concentrations of soil (2%, 5%,  10%) and
compound were mixed with  the  nutrient medium and stirred in the reactor flask.  The
flask was connected  to  the oxygen  generation flask  and pressure  cell  of  a 12 unit
VOITH electrolytic respirometer.

       The oxygen uptake data was then analyzed on the computer,  using the Monod
equation combined with a linear adsorption  isotherm, to determine  the soil adsorption
parameter, and the Monod  biodegradation parameters.  The model equations  for a soil
slurry  respirometer reactor flask have been  summarized  below.




   Caq  soil concentration [ mg/L ]

   Kd  soil adsorption coefficient [ L/mg ]

   KS   Michaelis constant [ mg/L ]

   C^   oxygen uptake [ mg/L ]

   Saq  substrate concentration in aqueous phase [mg/L]

,     ,Sp   byproduct [mg/L]

     Ss   substrate [ mg/L ]

„.    , t    time[HrJ      „                ,.              ,;

i     ,Y ,  yield coefficient [ mg/mg ]     ,

     Yp   bioproduct yield coefficient [ mg/mg ]

••:•••..  •& . .-...growth coefficient [1/Hr]

;         Carbon  dioxide  generation rates were measured in shaker flasks, wherein the
  .soil  sample was shaken with  the nutrients  and  compound. A packed bed of soda lime
  pellets  was used  to  absorb the  generated  carbon  dioxide. The upper bed  of soda  lime
  pellets  was used  to absorb the  carbon dioxide from the influent air, and the  lower  bed
  of soda lime pellets  was used to absorb carbon dioxide generated in the flask, due to
  biodegradation.                           ,

         The soda lime pellets  were then removed  periodically from the shaker flask,  and
  analyzed  for the  amount of carbon  dioxide generated.


         Three chemical  compounds, phenol, p-cresol, and 2,4  dimethyl  phenol,  were
  selected for the soil respirometric degradation test.  Three different compound
  concentrations: 50 mg/l,  100  mg/l,  and 150 mg/l,  and three  different soil
  concentrations, 2%, 5% and  10% were selected for the initial studies.

         Figure 1 shows the  oxygen uptake  curve for phenol at 100 mg/l concentration
  and  various soil concentrations: 2%,  5%, and 10%.

         A  newly developed adaptive random search technique was used to determine
  these parameters  from the  experimental data.   Table 1 presents the  results of the
  analysis for the experimental  data presented earlier in Figure 1.  it can  be  seen that
  the  Monod biokinetic parameters, u and Y  do  not vary with soil concentration, while
  other parameters  change dramatically at 10%  soil concentration.  This is expected due
  to the  fact that at higher soil concentrations, significant mass transfer effects occur in
  the  bioreactor  system.  This finding  can have  a significant impact on the design and
  operation of soil  slurry reactors.  Furthermore, the  physical  soil adsorption parameter,
  Kd,  decreases as the substrate concentration increases, which is expected  from  a
  nonlinear adsorption  isotherm.

         The experimental value for the  soil adsorption parameter, KOc reported in the
  literature (6)  is 27.  Since Kd  is  defined as KOc x (percent organic carbon in  soil), the
  experimental value of  Kd is  27  x 0.06 = 1.62.  The soil adsorption parameter values
  obtained from  respirometry are  in the range of 1.02 -  3.899.

       Figure 2 shows the cumulative carbon dioxide generation data for 5%  soil
 concentration and  phenol  concentration Varying from 0 to  150  mg/l.  The total  amount
 of  carbon dioxide generated increases with the  compound concentration.

       The  carbon dioxide generation  data  provides unambiguous measurement of
 biodegradation  kinetics for complete  mineralization  of  the compounds.   Reconciliation
 of  carbon dioxide  generation data with  oxygen  uptake information is important  in
 determining the biokinetics of not only biotransformation reactions, but also  for
 complete mineralization of the compound.


       Respirometric studies with soil slurry reactors provides  valuable insight  into the
 biodegradation kinetics of compounds adsorbed in soil phase.  It has been shown that
 a Monod kinetic equation  in conjunction with a linear adsorption isotherm can  provide
 reliable  estimates of the Monod kinetic parameters.   Experiments conducted  in our
 laboratory have demonstrated  that cumulative carbon dioxide measurement can be
 made for soil slurry systems.
(1)    Goring,  C.A.I., Hamaker,  J.W., Organic Chemicals  in the Soil Environment,
       Marcel Dekker, New York, 1972.

(2)    Boethling, R.S.,  Alexander, M., Microbial  degradation of organic compounds at
       trace  levels, Environ.  Sci.  Techno!., 13: 989-991, 1979.

(3)    Brunner, W., Focht,  D.D., Deterministic three-half-order kinetic  model for
       microbial degradation of  added carbon substrates  in soil, Appl. Environ.
       Microbiol, 47:  167-172,  (1984).

(4)    Anderson, J.P.E., Domsch, K.H.,  Quantification  of bacterial  and fungal
       contributions to soil respiration, Arch. Mikrobiol. 93: 113-127, 1973.

(5)    Tabak, H.H., Govind, R.,  Determination of Biodegradation kinetics with the use
       of  respirometry  for  development of predictive structure-b!odegrada1:ion
       relationship  models, Paper presented at the IGT Symposium,  Colorado Springs,
       CO,  December  1991.

(6)    Kenega, E.E.,  Goring,  C.A.I., Relationship between water solubility,  soil
       adsorption, Octanol-water partition, and  Bioconcentration of Chemicals in Biota,
       In  Eaton, J.C., Parrish, P.R., Hendricks,  A.C.  (Eds.) Aquatic Toxicology, ASTM
       STP 707, Philadelphia, PA:  American Society for  Testing  and  Materials,  1980.

       FIGURE i    Phenol biodegradalion  in soil slurry  reactor

                      Phenol concentration = 100 mg/L
                                  Time (hr)








         FIGURE 2   Phenol biodegradation in soil slurry reactor

                      Phenol concentration =  150 mg/L
                                  Time (hr)

  Table 1:  Phenol concentration = 100 rag/1
Soil concentration :
5% 10%

Monod parameters:
H [1/hrJ
Ks [me/Li
Y [me/me]
Yp Crne/me]
b fl/hrl
0.535 0.551
11.4 1.12
0.477 0.388
0.0209 0.00709
0.0295 0.00709

Adsorption parameter :
Kd IL/Bl
3.84 2.54

3.84 16.5
 RSSE: Residual sum of squared errors
 All  mass measurements are as COD
 Table 2: .Phenol concentration =  150  mg/1
Soil concentration :
• 2%


u. [1/hr]
Ks fmz/Ll
Y [me/msl
Yp (me/me) ;
b fl/hrl




Adsorption parameter :

Kd FL/el
1 .02 -


RSSE:  Residual sum of squared errors
All mass measurements are as  COD

            o>  g>  E E
            p  E o o
            C  O O LO
            O  IT) T- -I—

            ^  c\r oT ^
                               ^  LJJ
1/Boi 'Q31Va3N3O 2OO



                 Judy L Hessling, Edward  S. Alperin, and Arend Groen
                                       IT Corporation
                                    11499 Chester Road
                                  Cincinnati, Ohio 45246
                                      (513) 782-4700

                       Richard P. Lauch and Jonathan G. Herrmann                 ^
                          Risk Reduction Engineering Laboratory
                          U.S. Environmental Protection Agency
                             26 West Martin Luther King Drive    .
                                  Cincinnati, Ohio 45268
                                      (513) 569-7237


        Contaminated soil and debris (CS&D) pose a special problem because of their complexity and
 high degree of variability. Therefore, the EPA has determined that a detailed evaluation of treatment
 technologies for CS&D is needed to develop separate Land Disposal Restriction (LDR) standards
 applicable to their disposal. These standards are being developed through the evaluation of best
 demonstrated available technologies (BDATs).  Once these LDRs are promulgated, only CS&D wastes
 that meet the LDR standards will be permitted to be disposed of in land disposal units.

        As part of the effort to establish the standards, a thermal desorption treatability study was
 performed for the U.S. EPA to supply information as part of the data base on BDATs for CS&D
 remediation. Thermal desorption has been successfully tested at both the bench and pilot scale on a
 wide range of organic contaminants. During this'study, thermal desorption was investigated for removal
 of creosote from soil at a process temperature of 550°C.

        The contaminants of concern in the soil were polycyclic aromatic hydrocarbons (PAHs),
 semivolatile contaminants that boil at temperatures  ranging from approximately 215°C to greater than
 525°C.  Vapor pressures of these compounds vary depending on whether the contamination consists of
 one compound or a mixture of compounds. Because the -boiling points 'of various' mixes of
 contaminants are not known, bench-scale thermal desorption tests were performed to determine the
 optimum temperature and residence time required for removal of these compounds from the soil.  The
 thermal  desorption study was performed in two phases-bench-scale and pilot-scale.  Based on the
 results of the bench test, a pilot-scale test for the thermal desorption technology was performed at an
 operating temperature of 550°C and a residence time of 10 minutes to reduce the PAHs present in the


       The thermal desorption pilot plant evaluated under this project consisted of a continuously
 rotating  desorber tube partially  enclosed  within a gas-fired furnace shell. Small  baffles were  located at
 Intervals within the tube to provide soil mixing.  A stationary thermowell was extended from the dis-
 charge end into the tube with six thermocouples to  monitor the soil temperature and three to monitor
the gas temperature along the tube length. The furnace was a refractory-lined chamber.  The 14 equally

spaced burners were controlled by a standard burner control system with appropriate safety features.
Temperature measurements for furnace burner control or monitoring were taken by four thermocouples
that contact at various locations on the outer metal wall of the rotating tube beneath the furnace
refractor.  The furnace flue gas was discharged directly to the atmosphere through a remotely positioned
exhaust duct.  The desorber was rated at 320,000 British thermal units (Btu) maximum heat duty. A
nitrogen purge was continuously introduced to the desorber at a low rate of 2 cubic feet per minute to
help flush contaminants and to maintain an atmosphere that does not support combustion (i.e.,  <6
percent oxygen).  The residence time was measured before the study by placing colored aquarium
gravel into the feed hopper and visually observing its discharge from the desorber. The average
retention or residence time in the tube was calculated as the difference between the time the colored
gravel was placed  in the screw feeder and the time it was discharged.  Solids discharged from the
desorber during steady-state operation were weighed on a digital electronic scale to determine the  soil
feed rate.

       The Superfund soil that was tested during the project was a fine, sandy soil (75  percent of the
particles were between 0.1 and 0.4 mm in diameter). The soil had a relatively low moisture content of
approximately 10 percent and a heating value below 500 Btu/lb.

       Various temperatures and soil residence times were evaluated throughout the bench-scale
testing program. The results obtained for the removal of semivolatile organics from the  soil under
various operating conditions are summarized as follows:

        Run No. 1  (300°C at 10 min.) removed 96.4 percent
        Run No. 2 (425° C at 10 min.) removed 99.97 percent
        Run No. 3 (550°C at 10 min.) removed 99.995 percent
        Run.No. 4 (300°C at 20 min.) removed 97.4 percent
        Run No. 5 (550°C at 5 min.) removed >99.9999 percent

        Based on the results obtained during the bench-scale study, temperature and residence time
operating conditions  of 550°C and 10 minutes were established for  the pilot-scale testing program.  The
total residence time for the soil in the thermal desorption  system was 20 minutes.  This total residence
time included three phases:  1) bringing the soil to 550°C, 2) treating the soil  at that temperature for 10
minutes, and 3) cooling the soil before its discharge. Although the  bench-scale results indicate that the
run at 550°C and a 5-minute residence time provided the highest removal efficiencies for the semivolatile
contaminants, larger  particles were expected to  be introduced into  the pilot-scale unit, in which case the
feed streams might not be totally uniform and could contain "hot spots." Therefore, a temperature  of
550°C and a residence time of 10 minutes were  chosen to obtain better treatment of the contaminated

        Six sets of temporally related soil samples (waste feed and  treated residual) were collected
during the thermal desorption pilot test to evaluate the performance of the technology for the treatment
of creosote-contaminated soil. Additional samples of the off-gases  were collected to characterize the
emissions from the unit prior to the air pollution control equipment  to determine if any degradation
products were being formed.


        Table 1 presents the average concentrations of organic contaminants in the soil before and after
treatment on a dry weight basis.  On the average, total semivolatile organic contaminants were reduced
from 4635 milligrams/kilogram (mg/kg) to  less than the detection limit.   Hence, average removal of total
semivolatile organics was greater than 99.9 percent.

lndeno(1 ,2,3-cd)pyrene

580 ,
Total 4635
< 0.043
< 0.023
< 0.033
< 0.007
< 0.081
< 0.020
< 0.034
< 0.073
< 0.052
< 0.023
< 0.047
< 0.035
< 0.320
% Removal
> 99.99
> 99.89
> 99.98
> 99.94
:> 99.97
:> 99.99
> 99.98
> 99.99
:> 99.99
> 99.92
> 99.97
> 99.86
> 99.86
> 98.77
> 99.97
 NA = Not applicable.

        No appreciable reduction in lead or arsenic was observed during the study because of the low
operating temperature in relation to the boiling points of lead and arsenic; however, mercury, which has
a boiling point of 356°C, was reduced from 19.3 mg/kg to 0.8 mg/kg.

        Air sampling was performed to characterize the gases coming off the treatment system before
they reached any air pollution control  equipment. The results of the air analyses showed a
predominance of aromatic compounds. All of the more complex aromatics detected in pretreatment soil
were also detected in the off-gas.  In addition, phenolic compounds as well as volatile organic
compounds such as benzene, toluene, and xylene were detected in the air samples.  The fact that these
compounds were not detected in the soil indicates they could have been masked by the more concen-
trated contaminants in the soil or the possible degradation of the more complex PAHs to form lower-ring


        Bench tests should be performed first to determine the best operating temperature and
residence time for the pilot-scale desorber with specific soils.  For this study,  a residence time of 10
minutes at a temperature of 550°C was selected from bench-test results for optimum operation of the
pilot-scale desorber.  Volatile organic contaminants were below the detection limit in  both the
pretreatment soil and the posttreatment soil.

        On the average, the pilot-scale desorber reduced total semivolatile  organic contaminants from
4635 mg/kg to less than the method detection limit, a removal rate of greater than 99.9 percent. All  of
the individual semivolatile organics were reduced to concentrations below the method detection limits.
The highest average individual contaminant concentration in the pretreatment soil was 1028 mg/kg for
phenanthrene, and this concentration was  reduced to less than the method detection limit of 0.034
mg/kg in the posttreatment soil.

        The off-gas from the pilot-scale desorber contained all of the semivolatile organics in
approximately the same proportions that were present in the pretreatment soil. Some phenols and
volatile organic compounds (e.g., benzene, toluene, and xylene)  were detected in the off-gas.  This
indicates that some degradation of the higher-ring compounds to lower-ring compounds was taking

        No appreciable volatilization of lead or arsenic occurred  in the pilot-scale desorber. Mercury,
which has a boiling point of 356°C, was 90 percent vaporized from the soil  in the pilot-scale desorber.
Release of the mercury to the atmosphere was prevented by the high-efficiency paniculate air (HEPA)
filter and carbon adsorber.                                                 .


IT Environmental Programs, Inc.  1991. On-Site Engineering Report for the Low-Temperature Thermal
Desorption Pilot-Scale Test on Contaminated Soil. Volumes I and II.  Prepared for the U.S.
Environmental Protection Agency, Office of Research  and Development, Risk Reduction Engineering
Laboratory, under Contract No. 68-C9-0036.

                   Alan B. Jones, Madonna R. Brinkmann and William R. Mahaffey
                                       ECOVA Corporation
                                     18640 - N. E. 67th Court
                                   Redmond, Washington 98052
                                         (206) 883-1900
        ECOVA Corporation conducted pilot-scale process development studies in 1991 using a slurry-
 phase blotreatment design to evaluate bioremediation of polycyclic aromatic hydrocarbons (PAHs) in
 creosote-contaminated soil collected from a superfund site.  Bench-scale studies were performed as an
 antecedent to pilot-scale evaluations in order to collect data which would be used to determine the
 optimal treatment protocols. This study was performed for the U.S. EPA to supply information as  part of
 the database on Best Demonstrated Available Technology (BOAT) for soil remediation. The database will
 be used to develop soil standards for land disposal restrictions. This paper is a summary of the
 complete on-sfte engineering (OER) report that is available from the U.S. EPA.
        The site is a former railroad tie-treating facility. Two surface impoundments were used for the
 disposal of wastewater generated from wood-treating processes (Resource Conservation and Recovery,
 Act waste code K001). Although all wastewater and liquid creosote have been removed from the
 Impoundments, there is an estimated 12,500 cubic yards of soil and sludge  remaining that is
 contaminated with 2-,  3-, and 4+-ring PAHs.  There is also some groundwater contamination restricted
 to a relatively small area downgradient from the site.
        A landfarming operation has been conducted on contaminated soil and sludges at the site since
 1986.  Although this work has attained significant reductions in 2- and 3-ring PAHs, the degradation of
 the 4+-ring PAHs and benzene-extractaWe  hydrocarbons has  been less successful. A significant
 improvement In blodegradation rates of the 4-ring and larger PAHs is possible through the* use of slurry-
 phase biological treatment vs. landfarming.  In this process, the soil is suspended to obtain a pumpable
 slurry which Is fed to a large-capacity continuously stirred tank reactor (CSTR). The reactor is then
 supplemented with oxygen, nutrients, and, when! necessary, a  specific inocula of microorganisms to
 enhance the biodegradation process. This method of treatment has several advantages because the
 engineering and biotechnology required to provide an optimal  environment for biodegradation of the
 organic contaminants can  be controlled with a high degree of  confidence.  Often, biological reactions
 can be accelerated  in a slurry system-because of the increased contact efficiency between contaminants
 and microorganisms due to the higher sustained levels of bacterial  populations in the aqueous phase
 (e.g., 10-109 colony-forming units/millilrter (cfu/mL)).  In a 30% slurry this translates to 109-101°
 cfu/gram of sol! which is 10- to 100-fold higher than typically attainable in solid-phase treatment


        Physical characterization of the site soils indicated that there was a substantial amount of heavy,
 coarse-grained  particles. The percentage volume of soil fines which was less than  100 mesh was only
9%.  This suggested that there would be appreciable difficulties in generating a manageable slurry with
this soil. Another important observation was the presence of hardened inclusions of creosote which
were pulverized when substantial shearing forces were applied. Consequently, a soil pretreatment was
 required prior to charging pilot-scale reactors.  Normally,  a soil of this nature would be subjected to soil
washing to remove contaminants from oversize materials (+100 mesh) and  yield a pregnant slurry
enriched in smaller particulates (-100 mesh).  However, to meet the requirements of the EPA's program,
the pretreatment step chosen was a soil milling process which  crushed larger particles yielding a soil
enriched in -100 mesh particles.

       Pilot-scale bioreactors (5) were EIMCO 64-liter stainless steel containers incorporating an airlift
system and rotating rake attachment.  The reactors were filled with a 30% slurry (w/v, soil in water)
amended with nutrients and an inocula of PAH-specific degrading microorganisms.  Nutrients were
adjusted to provide an optimal ratio of Total Organic Carbon (TOC) : Nitrogen (N) : Phosphorous (P).  A
microbial evaluation of the contaminated soil was conducted to determine the size and diversity of
bacterial populations and the ability of these organisms to degrade polycyclic aromatic hydrocarbons.
Enrichment culture techniques and selective plating procedures were used to isolate and characterize
PAH degrading organisms.  Reactors were inoculated with specific PAH degrading organisms
indigenous to the soil (P. fluorescens, P. stutzeri, and Alcaligenes sp.) at a concentration of 9.3 x107
per gram of soil.  Rake speed, airlift volumes, temperature, pH, dissolved oxygen, and foaming were all
monitored over the course of the study.

       Chemical analyses were performed on composited soil samples to determine contaminant levels.
Analysis for semivolatile contaminant levels was performed according to EPA Method 8270 (SW-846).  In
addition, soil was analyzed for polycyclic aromatic hydrocarbons by HPLC (ECOVA Site Support
Chemistry [SSC-6]), total petroleum hydrocarbon (TPH) by infrared spectroscopy (IR) (EPA method
418.1), and total  organic carbon (TOG) and inorganic nutrient ions (NO3, NH4, PO4, SO4) by standard
chemical methods (ECOVA SSC-17, ECOVA SSC-14, ECOVA SSC-15, and EPA 375.4, respectively).  The
inorganic nutrient data were used to determine whether, based upon TOC, the levels and ratio of
nitrogen (N), o/ffto-phosphate phosphorous (P), and sulphur (S) were sufficient to support optimal
microbial activity. In addition, a soil toxicity test was performed using Microtox procedures.  The pilot-
scale study was conducted for 12 weeks.

       This project demonstrated
optimum treatment of PAHs by
slurry-phase biotreatment in stirred
batch reactors.  Baseline analyses
of PAH concentrations in the soil
are illustrated in Table 1.
Naphthalene,  acenaphthene and
fluoranthene were the constituents
present at the highest levels. Total
PAH levels in  these soils averaged
10,970 ± 1,515 gr. / kg dry soil
(parts per million, ppm).  The 2- &
3-ring PAHs constituted 5,890 ±
1,469 ppm and the 4- to 6-ring
PAHs constituted 5,080 ± 367 ppm
of the total.
lndeno(1 ,2,3-cd)Pyrene
Mean (5)
Std Dev.

        Pilot-scale results for
reductions In total PAH of 89.
with an overall PAH
reduction of 93.4 ±
3.2% over 12 weeks.
With respect to the
more biodegradable
and bioavailable  2- & 3-
ring PAHs, a reduction
of 95.9 ± 1.8% occurred
within two weeks with
only a slightly increased
overall reduction to
97.14 ± 2.2% over 12
weeks  (see Figure 2).
Reductions in the 4- to
6-ring PAHs, which are
less biodegradable and
bioavailable  and  usually
are not preferred
carbon sources for
bacterial growth, were
81.58 ± 6.7% after two
weeks.  After 12 weeks,
further significant
reductions were
observed in  the 4- to 6-
ring PAHs totalling
89.06 ± 4.8% (see
Figure 3). After nine
weeks, two of the five
reactors were
resuppiemented with
inoculum and two with
inoculum and surfactant
(Tween 80).  These
amendments did not
stimulate further
reductions in PAHs
during the time period
from week 9 to week

        Specific PAH-
degrading bacterial
populations were
monitored over time.
Bacteria were grown on
mineral salt agar and
mineral salt agar with
phenanthrene or pyrene
as carbon sources.
PAH biodegradation paralleled the bench-scale study results. Optimum
3 ± 3.9% occurred during the first two weeks of treatment (see Figure 1)

inonn ,
5 8000 i

0 J

' ^-"i : ! ' ' ' !•'•''
*^( A . , . ; i ; — • — * Reactor #1
t\ ' -\-— "-~: 	 •"*-• 	 ' 	 — ••---- .•---.; 	 -.--' ; 	
V \ \ " " .1 L — D — Reactor #2

\lir V ; ; ; ! ! ~~° — "Reactor #5
--^4;^^^^--— --^ —Reactor^
; y=»~-<^— * ^HZ^^^^f 	 *— 4
1 2 3 4 6 9 10 11 12
       Figure 1. Total Polycyclic Aromatic Hydrocarbons
9000 i

ci_ i



.it ii
r r ' ' '< " " " '"" r r 	 " 	 	
\ • • i • i • i i ma 	 i 	 jii

Vsj™,1 	 '• _; : ' ! [ -'—a— Reactor #2
L\\ : ...;:' :
V\\\i : : i ! f I , • , ~ — • — Reactor #4
\\ V •'.•:;,;
\v \ ! ~ ~ ~! 	 r~ ~"! I""" 	 ; 	 "" 	 1 ~^<> — Reactor #5

1 2 3 4 6 9 10 11 12
    Figure 2.  2- & 3-Ring Polycyclic Aromatic Hydrocarbons
                                                        • Reactor #i

                                                        • Reactor #2

                                                        • Reactor #4

                                                        • Reactor #5

                                                         Reactor #6
   Figure 3.  4- to 6-Ring Polycyclic Aromatic Hydrocarbons

media was used to screen for strains which might be capable of cooxidizing PAH's while growing on an
alternate carbon source. Specific PAH degrader population levels declined over the course of the
project (see Figure 4). The PAH cooxidizing populations exhibited the most significant and rapid
declines.  This may reflect that bacteria that utilize salicylate are more likely to degrade naphthalene.
Once naphthalene levels have been depleted, these populations may become carbon-source limited and
death will occur.  An interesting observation is that populations capable of utilizing pyrene and
phenanthrene as sole
carbon sources appear
to be sustained
throughout the study.
Between weeks 10 and
12, pyrene degraders
exhibit the most
significant population
declines.  Total
heterotrophic bacterial
counts also do not
appear to decline over
the 12 weeks. These
data suggest subtle
shifts in bacterial
populations from low-
molecular weight PAH
degraders to higher-ring
PAH degraders.
                            1.00E + 10

                            1.00E + 09

                            1.00E + 08

                         2  1.00E+07



IHMi   IT II I! ! ? ri H H   3ftn i  Iff la; i 4 jj 3 3K i [ [313 JI911 if  walgj (M

                                               • PMSS-PHEN

                                               ' PMSS-PYFt


                                   Figure 4.  Mean Value of Microbial Enumerations
                                                     MESH SIZING IN MILLIMETERS
                                                              POST MILLING
                                                                                8 WEEKS
        An important
phenomenon that
occurred with these
soils in the continuously
stirred tank reactors
(CSTRs) was a further
comminution of the soil
despite  extensive ball
milling.  Figure 5 shows
the effect of both the
milling and CSTR
comminution on particle
size distribution. After
milling, there was an
enrichment of the
particle  fraction smaller
in size than 0.21 mm at
the expense of larger
size particles.  This
allowed development of
a manageable slurry.
After 8 weeks of CSTR  stirring there was an enrichment in the fraction with particle sizes Jess than 0.15
mm.  This resulted in an appreciable thickening (viscosity) of the slurry itself and also an increase in the
extraction efficiency of  PAHs from soil particles. Between weeks 3 and 9 the levels of PAHs increased
with the most significant increases observed in the 4-to 6-ring PAH fraction. These phenomenon may
reflect the increased bioavailability of soil-bound PAHs due to comminution of soil particles which would
also contribute to increased slurry viscosity.  PAHs were reduced by 94%, of which 2- and 3-ring
compounds were degraded 97% and 4- to 6-ring compounds degraded by 90%. Factors contributing to
                                         Figure 5.  Particle Sizing Data

the lack of further decline of total PAHs may be: bacterial utilization of metabolic degradative
Intermediates as a preferential carbon source, a reduction of the more readily biodegradable 2- and 3-
ring PAHs to below levels which sustain an acclimation of biomass, the low bioavailability of the more
recalcitrant 4-, 5-, and 6-ring PAHs, or the generation of inhibitory metabolic end-products which repress
catabollc activity.


       Slurry-phase biotreatment of creosote-contaminated soils offers an efficient and rapid process
for reducing the toxic PAH components of this waste class (K001).  Soils from this superfund site
possess a robust population of PAH degrading  bacteria capable of efficient biodegradation of these
compounds.  Optimal biotreatment of these waste components can be stimulated by adjusting inorganic
nutrient levels, providing adequate aeration with mixing, and controlling the pH,  Finally, material
characterization of soils is critically important in assessing the feasibility of using slurry-phase reactors to
bloremediate contaminated  soils.


1.     Onsite Engineering  Report Of The Slurry-Phase Biological Reactor For Pilot-Scale Testing On
Contaminated Soil, Vols. I & II, by IT Environmental Programs, Inc, Cincinnati, OH. Technical Project
Monitor: Richard P. Lauch, Water and Hazardous Waste Treatment Research Division,  Risk Reduction
Engineering Laboratory, Cincinnati, OH.  October, 1991 (in review).              ,    .    ,


       The authors gratefully acknowledge the technical assistance of Christopher M. Krauskopf and
the expertise and assistance of Harlan A. Borow, both of ECOVA Corporation.  The authors wish to also
thank Richard Lauch, U.S. EPA/Cincinnati, for his helpful comments and guidance.

                             Mark M. Benjamin and Ronald S. Sletten
                     Dept. of Civil Engineering  FX-10, University of Washington
                              Seattle, WA 98195, Tel: 206-543-7645
        This project investigated the potential application of a combination adsorbent-filtration media for
treatment of heavy metals from Superfund sites. The media is comprised of ordinary filter sand onto
which a layer of iron oxide had been coated. The coating was applied by heating a solution of iron nitrate
to dryness under controlled conditions in the presence of the sand. The final product was about 1 to 2%
Fe by weight. The coating was a few micrometers thick on sand grains of diameter around 400 mm, and
it increased the surface area of the bulk solid from about 0.04 to about 7 m2/g.

        Since iron oxide is known to be a good adsorbent for heavy metals, it was hoped that the
modification of the surface of the sand would allow the sand grains to adsorb soluble heavy metals as
they passed through a column packed with the media. At the same time, it was anticipated that the
coated sand would perform comparably to plain sand as a media for collecting particulate metals.  Thus;
the goal of the project was to assess the ability of the coated sand media to remove soluble and
particulate metals simultaneously as water containing those species passed through the column.
        Runs were conducted using synthetic influents and a treated, metal-bearing water from a
Superfund site.  Preliminary runs used laboratory-prepared solutions containing 0.5 or 5.0 mg/L each of
three metals (Cu, Cd, and Pb).  Most of these tests were conducted at pH 9.0 using a 2-minute empty
bed detention time, corresponding to a hydraulic loading rate of about 11 gal/min-fr. Runs were also
conducted to characterize the effects on metal behavior of ammonia (as a complexing agent), EDTA (as
a chelating agent), or sodium dodecyl sulfonate (a surfactant) in the influent solution, and of biogrowth in
the column. At the end of the project, a few tests were run with a solution collected from a Superfund site
where conventional treatment is currently being applied.  During all runs, influent and effluent metals
concentrations were monitored, and, in most cases, soluble and particulate metals were analyzed

       After most runs, the media was backwashed to remove the particulates that had been collected.
It was then regenerated at pH around 2.0 to remove the soluble metals that had sorbed. The
backwashing step was skipped if the influent in the previous run did not contain particulate matter.
Regeneration efficiency was monitored and characterized as a function of operating conditions during the
regeneration step.
       In runs with 0.5 mg/L each of uncomplexed Cu, Cd, and Pb in the influent, the majority of the
influent metal load was soluble.  Between 7000 and 13000 bed volumes of influent were treated

effectively prior to substantial metal breakthrough. Before breakthrough, the metal concentrations in the
effluent were quite steady, with virtually no short-term fluctuations.  Typical effluent concentrations of total
Cu, Cd, and Pb were substantially less than 0.1 mg/L each.

       In the runs with influent nominally containing 5 mg/L of each uncomplexed metal (in reality,
influent metal concentrations varied between about 3 and 7 mg/L), most of the influent metal load was
particulate; soluble influent concentrations were typically around 1.5 mg Cd/L, 0.8 mg Pb/L, and 0.2 mg
Cu/L. For the purposes of this discussion, a "run" is defined as the time between sequential regeneration
cycles. Several batches of influent were treated during each run. During the course of these runs, the
media was backwashed over 20 times and regenerated about 10 times over a period of a few months,
with no apparent deterioration in performance.

       Atypical breakthrough  curve for these tests is shown in Figure 1. The total concentrations
(corrected for background) of all the metals in the effluent were well below 0.1  mg/L until about 150 to
200 bed volumes had been treated. Removal of soluble metal  was always significant throughout these
runs, and was very good at least until the point of particulate breakthrough. Particulate rnetals began
breaking through the column after about 200 to 400 bed volumes had been treated over a 6- to 12-hour
period. Typical removal efficiencies for soluble metals in the influent were 80% for Cu, 90% for Pb, and
98% for Cd, and typical overall  removal efficiencies (comparing total effluent and total influent) were 99%
or greater for all three metals (Table 1).
       1 T
      0.8 - -
    •S 0.6 -•
      0.2 •"•



                                         Bed volumes
Figure 1. Breakthrough curve showing total and soluble metals in column effluent as a function
of the volume of water treated. Influent conditions: Cu = Cd = Pb = 5mg/L; pH = 9.0, Empty bed
detention time = 2 min.

TABLE 1 . Soluble metals in column influent and effluent at various times during'run 1 5.

Time of Sample
Batch 1 , BV 3
Batch 1,BV 13
Batch 2, BV 3
Batch 2, BV 45
Batch 2, BV 63
Batch 3, BV 6
Batch 3, BV 260
Soluble Influent, mg/L

Cu Cd Pb
98 825 523
105 863 548
355 933 468
127 1603 683
160 1891 739
77 578 392
248 1710 697
Soluble Effluent, mg/L

Cu Cd Pb
23 26 3
23 17 39
.16 0 0
/ 25 27 84
24 31 140
23 12 83
63 59 109
% Removal of Soluble
Metals ,
Cu Cd Pb
77 97 99
78 98 93
95 >99 >99
80 98 88
85 . 98 81
70 ' 98 79
75 97 84
        Headless usually reached 25 psi near the time when particulate breakthrough occurred. At this
point, the column was backwashed with pH 9.0 water, and the next batch of influent was fed into the
system.  The backwash water typically contained a few hundred mg/L of each metal. After the first batch
of water had been treated, particulates broke through relatively soon after each backwash step. Thus,
backwashing with water adjusted to pH 9.0 did not return the column to its original filtration capacity.
However, despite the fact that particulates broke through the column more rapidly in batches 2 and 3
than in batch 1, the effluent values prior to breakthrough during treatment of all three batches were
comparable.  When breakthrough did occur, it was due to particulate metals passing through the column;
the columns did not appear to reach adsorptive saturation in any of the three batches.  Thus, it appears
that additional batches could have been run successfully before the column needed to be regenerated.

        The regeneration protocol was to circulate either 4 or 8 bed volumes of water adjusted to pH 2.0
through the column.  After two hours, an additional 4 to 8 bed volumes was  passed through the column
and not recirculated.  The metal concentration in the  recirculation fluid increased rapidly at first and then
only slowly thereafter. Based on these results, it appears that a recirculating period as short as 10
minutes would release a large fraction of the available metal. Metal concentrations in the first and second
regenerant solutions were as high as 3000 and 500 mg/L after the 5 mg/L runs, and about a factor of 5
lower after the 0.5 mg/L runs.                               ;

        Interestingly, only about 40 to 75% of the particulate metal load that was removed by the column
was recovered during the backwashing step. Most of the remainder was recovered during the acid
regeneration step, suggesting that once the particles collide with the media,  they form strong bonds to it.
Overall recovery efficiencies (backwash plus regeneration) Were almost always greater than 80% and
were often 100% ± 10% (Table2).                                                  ...  •

TABLE 2. Recovery of metals from the column after various treatments after run 15.

Batch #



Me Removed

Soluble Me




Total Metal



       When sufficient ammonia was added to the solution to keep all of the influent Cu and Cd (5 mg/L)
soluble, about 4000 mg each of Cu and Cd could be sorbed onto the media at pH 10.  Regeneration of
this column using a total of 16 bed volumes of regenerant solution at pH 2.0 recovered 93% of the sorbed
Cd and 100% of the Cu. Thus, at least some complexing agents do not interfere with the performance of
the media.  On the other hand, when EDTA was added at a ratio of 1.25 mols EDTA/mol metal,
breakthrough occurred very quickly, both at pH 10 and pH 4.5. The adsorptive filtration process appears
not to be applicable for waters containing such a strong chelator. In situations where complexed metals
need to be treated, tests investigating the behavior of the specific complex will be required.

       Sodium lauryl sulfonate is a surfactant that might interfere with the process by interacting either
with the metals or the surface of the media. Thirty mg/L of this surfactant had no noticeable effect on
metal sorption.

       In the one test that was run using media on which biogrowth had occurred, the biofilm apparently
reduced the capacity  of media for the metals by about 50%. This interference could probably be
reversed by exposing the column to a high  pH solution, which would solubilize a substantial amount of the

       One set of tests was conducted using a treated, metal-bearing wastewater from a Superfund site.
Unfortunately, this solution could not be treated under optimal conditions for our process, since massive
amounts of CaCO3 precipitated when the pH was raised to 9.0. Therefore, the water was treated at pH
8.0.  The only metal present in significant quantities in this water was Zn, for which the total and soluble
concentrations were in the ranges 0.6 to 4.0 and 0.3 to 0.6 mg/L, respectively. As shown in Figure 2,
typical total and soluble Zn concentrations in the effluent were 0.15 and 0.05 mg/L, respectively. Thus,
even though the test could not be run under optimal conditions, it did demonstrate that the adsorptive
filtration process could work on such a water. Chances are that the outcome would have been more
impressive if a water with lower Ca or alkalinity had been chosen for the test.

       1.0 -r
       0.8 --

       0.6 --
       0.4 --
       0.2 --
• Filtered Effluent

* Unfiltered Effluent

° Zinc blanks
                 4  ***   *»» ^AAAA****.*    *


                500    1000    1500    2000    2500   3000    3500    4000    4500

                                          Bed volumes
Figure 2.  Breakthrough curve showing total and soluble Zn in the column effluent during
treatment of water from a Superfund site (Run 3).  Prior treatment involved precipitation and
settling at pH = 8.0. Influent Zn concentrations quite variable with a mean value and standard
deviation of 0.73 ± 0.28 mg/L total and 0.40 ± 0.22 mg/L soluble Zn.
        To summarize, simultaneous sorption and filtration of Cu, Cd, and Pb are feasible using iron
oxide-coated sand under reasonable engineering conditions.  Soluble effluent concentrations of a few
tens of fig/L or less are achievable.  The media can remove particulate metals simultaneously from the
water, probably with an efficiency comparable to that achievable with conventional sand filtration.  The
media can be regenerated by exposure to an acid solution, yielding regenerant solutions containing metal
concentrations a few hundred times as concentrated as the influent. In our tests, filtration limited process
performance moreso than sorption, although this outcome is not generalizable: the limiting factor would
certainly depend on the specific chemical composition of the influent solution.


                                        Clifton W. Farrell
                                  Thomas W. Gardner-Clayson
                                    Electro-Pure Systems, Inc.
                                       10 Hazelwood Drive
                                    Amherst, NY  14228-2298
                                       Tel: (716)  691-2610
       Electro-Pure Systems (EPS) has undertaken a two-year laboratory program to investigate the
technical and economic viability of alternating current electrocoagulation technology (ACE Technology)
for Superfund site remediation. The ACE Technology offers a technologically simple mechanism to
achieve phase separation of liquid-solid slurries and liquid-liquid emulsions, and to remove soluble  ionic
pollutants (metals, alkaline metals, phosphate) from solution. Alternating current electrocoagulation was
originally developed as a treatment technology in the early 1980s to break stable aqueous suspensions
of clays and coal fines in the mining industry. The technology offers a replacement for primary chemical
coagulant addition to simplify effluent treatment, realize cost savings, and facilitate recovery of fine-
grained products that would otherwise have been lost.  The traditional approach for treatment of such
effluents entails addition of organic polymers or inorganic salts to promote flocculation of fine
partlculates and colloidal-sized oil droplets in aqueous suspensions.  These flocculated materials are
then separated by sedimentation or filtration. Unfortunately, chemical coagulant addition generates
voluminous, gelatinous sludges which are difficult to dewater and slow to filter. As an alternative to
chemical conditioning, alternating current electrocoagulation introduces into an aqueous medium highly-
charged polymeric aluminum hydroxide species which will neutralize the electrostatic charges on
suspended solids and oil droplets to facilitate their agglomeration (or coagulation).  These species  will
also coprecipitate many soluble ions.  ACE Technology prompts coagulation without adding any soluble
species and produces a sludge with a lower contained water content and which will filter more rapidly.
Through separation of the hazardous components from an aqueous waste, the volume of potentially
toxic pollutants requiring special handling and disposal can be minimized. Waste reduction goals may
be accomplished by integrating this technology into a variety of operations which generate contaminated

       Presented in this paper are preliminary results from the laboratory testing program conducted by
EPS under the auspices of the U. S.  EPA's Superfund Innovative Technology Evaluation (SITE)  program.
Performance data from a field test of a pilot-scale alternating current electrocoagulation unit are
summarized as well.


       Laboratory experiments were conducted in a bench-scale electrocoagulation  apparatus, referred
to as an ACE Separator™, on a series of synthetic wastes.  Two designs of the ACE Separator™ were
used:  a Parallel Electrode unit in which a series of parallel, vertically-oriented,  aluminum electrodes form
a series of monopolar electrolytic cells up through which the effluent passes, and a Fluidized Bed unit
which  consists of non-conductive cylinders equipped with rectilinearly-shaped, non-consumable metal
electrodes between which is maintained a turbulent, fluidized bed of aluminum alloy pellets.  Application
of an alternating current field to the electrodes prompts dissolution of the aluminum and formation of
highly  reactive polymeric hydroxide species. The Parallel Electrode ACE Separator™ was used in the
first year EPS  participated in the SITE program when the basic mechanism of electrocoagulation was

 believed to be electrostriction (polarization of electrical charges on colloidal particles by imposition of an
 alternating current electric field).  Experiments conducted with this version of the ACE Separator™
 primarily addressed the influence of frequency, residence time, field strength (electrode spacing), and
 current density of the applied AC current field.  The realization that treatment efficiency was primarily
 dependent upon aluminum ion production instead of upon the characteristics of the applied AC current
 field prompted development of the Fiuidized Bed ACE Separator™ which dissolves aluminum at least one
 order of magnitude more efficiently than the Parallel Electrode ACE Separator™. Experiments in the
 second year were conducted primarily with this newly-designed ACE Separator™.

         Experiments were conducted on two surrogate wastes which were prepared by EPS by
 combining measured quantities of the EPA's Synthetic Soil Matrix (SSM), supplied to EPS by EPA's
 Edison, NJ laboratory, with hydrocarbon and/or metal contaminants selected by EPS.  Both were
 prepared as stable aqueous suspensions of silt, clay and top soil containing approximately 1%
 suspended solids, with  or without spikes of toxic metals (Cd, Cr, Cu, Pb) and diesei fuel.  The clay
 surrogate waste contained solely the -40 mesh synthetic soil matrix fines while the second incorporated
 the fines fraction mixed with  1.5% No. 2 diesel fuel and 1% of a  strong surfactant. Experiments on
 metals and phosphate reductions were conducted on aqueous end-member solutions at neutral pH at
 two solution conductivities (1,500 and 3,000 (iS/cm). Metals and phosphate matrix experiments were
 conducted to determine the treatment conditions that would yield both acceptable metal reductions and
 a reasonable operating  cost (electrical power, aluminum consumption).  Electrocoagulation treatment
 efficiency was primarily determined by reductions  achieved in  the supernant phase of total suspended
 solids (TSS), turbidity, and soluble contaminant concentrations (metals, Chemical Oxygen Demand
 (COD)  for diesel fuel-spiked surrogates).  Improvements in solids settling rates and decreases in the
 moisture content of coagulated solids filter cakes were also measured.  Based upon the encouraging
 results of bench-scale tests of the Fiuidized Bed ACE Separator™, a portable, pilot-scale ACE
 Separator™ of this design with a nominal throughput capacity  of 70 gpm was designed, fabricated and
 tested for recovery of suspended colloidal-sized pigment (TiO2) from an industrial waste stream. The
 results  for treatment of the clay suspension surrogate, diesel-fuel  contaminated soil slurry  and metals-
 bearing solutions are summarized below.


 •   Clay-Metals Surrogate

        The clay suspension surrogate was spiked with four metal salts (Pb(NO3)2, CuSO4 • 5 H2O,
 CdCI2 • V4 H2O, CrCI3 • 6 H2O) at concentrations of 10-50 mg/l, thoroughly mixed, and
 electrocoagulated at operating conditions found to be optimum for effecting separation of clays from the
 surrogate.  While a  majority of the soluble metals strongly adhere to the clays, electrocoagulation
 enables agglomeration of the colloidal, metal-bearing clays and significant (>90%) reductions in the
 soluble metals loadings  (Table 1).  The filtration time for the treated surrogate decreased to
 approximately 50%  of that required for the  untreated  surrogate waste (3:02 minutes versus 6:00
 minutes).  Comparative chemical coagulant experiments with alum (AI2(SO4)3) and organic cationic
 polyelectrolyte flocculants  (Drew Polymer 485) were also conducted on the surrogate waste.
 Electrocoagulation yielded a faster filtration rate (2:15 minutes for 100 mis) than for either the  untreated
 slurry (7:30 minutes) or the alum-treated solution (3:53 minutes).   Polymer treatment had the same
 filtration rate.  Filter cake volume expressed as a percentage of the pre-filtered sludge volume seemed to
 be a minimum for ACE Separator™ treatment (6%) compared to alum and polymer treatment  (13-15%)
 The volume data indicate that the ACE Separator™-treated solids cakes are more compact and easier  to
 dewater than those for coagulant-treated samples.  Particle size analyses of the treated and untreated
 slurries  indicated that the mean size of the ACE Separator™-treated solids both in the supernant and
filtrate (25.2 and 35.1 microns, respectively) increased by a factor of 3-4 over that in the original slurry

(9.1 microns).  Larger particulate growth occurred as a result of electrocoagulatiqn than by either
polymer or alum addition (15 and 10 microns, respectively).
                                                       ACE SEPARATOR TREATED



: N.D.

*N.D.: Parameter not determined.
 •  Clay-Metals-Diesel Fuel Surrogate

        Electrocoagulation of the clay surrogate waste containing 1.5% diesel fuel and metals (Cu, Cd,
Cr, Pb)  produced effective reductions in suspended solids (112 to 12 mg/l), total carbon (230 to 110
mg/l) and total inorganic carbon (28 to 12 mg/l). Copper is reduced by 90-94%, cadmium and
chromium by 91-97% apd lead by 86-89% (Table 2).  No appreciable change in TOC loadings in the
supernant resulted from treatment; the TSS was reduced by approximately 90% from 222 to 19 mg/l.
Comparative chemical coagulant addition experiments were conducted for the diesel fuel contaminated
slurry. The following generalizations can be made for the treatment: alum and polymer treatments
generally required approximately 30% longer filtration times, ACE Separator™ and polymer treatments
reduce the total solids (TS) and TSS loadings to an equivalent degree (equal to four times the reduction
achieved by alum treatment) and better reductions in soluble metal  concentrations were usually achieved
with polymer and electrocoagulation treatment.  Particle size data confirm the appreciable enhancement
In the clay fraction as a result of electrocoagulation. The mean size of the ACE Separator™-treated
particulates both in the supernant and filtrate (188 and 20 microns,  respectively) has increased by a
factor of approximately 85 and 8, respectively, over that in the original slurry (2.2 microns).


                                                         ACE SEPARATOR TREATED
„ ..(Pig/I)
' 1,870

, 0.5


: N.D.

, 650
*N.D.: Parameter not determined.
 •  Metals and Phosphate Experiments                     .          .               ...:.'

        Matrix electrocoagulation experiments on the surrogate metals and phosphate-bearing solutions
 indicated excellent nickel, copper and phosphate concentration reductions.  Electrocoagulation by
 means of either design of the ACE Separator™ enabled in excess of 90% (concentration basis) of the
 phosphate and copper to be removed from solution at low aluminum and electrical power requirements.
 Reductions in the nickel concentration varied  between 78 and 91% (concentration  basis).  Table 3
 presents the analytical results for reductions for these three species from neutral solutions by means of
 both the Fluidized bed and Parallel Electrode  ACE Separators™ for representative matrix experiments.

 «  Pilot-Scale ACE Separator™ Demonstration
       A pilot-scale, portable Fluidized Bed ACE Separator™ equipped with four, 6" diameter'
electrocoagulation cells having a combined nominal throughput capacity of 70 gpm was designed and
manufactured. This unit was field-tested at a TiO2 pigment manufacturer to recbver fine-grained (<30n)
product from the overflow of a clarifier which contains 500-3,000 mg/l TjQ2. Electrocoagulation of the
overflow at a rate of 1-2 ampere-minutes/liter, corresponding to introduction of «15-17. mg/l aluminum,
followed by 5-10 minutes of gravity settling allowed recovery of 85-95% of the pigment! . Such treatment
reduces the TSS of the overflow stream from 2,000 mg/I to «50 mg/l; direct electrocoagulation of the
filtrate entering the, clarifier is another treatment possibility for enhancing its "operation. The. direct
operating  cost for this ACE Separator™ treatment required 5 KWH/1000 gallon's of electrical power and
«0.25 Ib. AI/1000 gallons for a total treatment cost of $0.50/1000 gallons.   Electrocoagulation enabled
recovery of »17 Ibs. TiO2/lOOO gallons that would  otherwise have been lost to a settling lagoon-'
Assuming a pigment price of $0.85/Ib. and an electrocoagulation operating cost of $0.50/1000 gallons
ACE Separator™ treatment will enable recovery of  *$14.00 of TiO2 from every 1000 gallons of clarifier

   FB 1.1 AMP, 180 SEC RT, 123 VAC
   FB 1.5 AMP, 540 SEC RT, 74 VAC
   PP 11.2 AMP, 240 SEC RT, 16 VAC
   PP 19.6 AMP, 168 SEC RT, 27 VAC

   FB 2.7 AMP, 150 SEC RT, 130 VAC
   FB 4 AMP, 120 SEC RT, 120 VAC
   PP 22.6 AMP, 144 SEC RT, 20 VAC
   PP 31.9 AMP, 221 SEC RT, 13 VAC

   FB 1.1 AMP, 144 SEC RT, 97 VAC
   FB 2.3 AMP, 14 SEC RT, 111. VAC
   PP 23.8 AMP, 60 SEC RT, 110 VAC
   PP 21 AMP, 225 SEC RT, 23 VAC
FB: Fluidized Bed ACE Separator™, PP:  Parallel Electrode ACE Separator11
RT: Retention Time

       ACE Separator™ treatment is effective in removing particulates from the soil suspensions,
Increasing the resulting mean particle size and, consequently, improving filtration properties.  The
technology has proven effective in reducing the metal concentrations in such slurries both by removing
the clays to which metal ions have adsorbed and by coprecipitating soluble species. The ACE
Technology is particularly applicable to zero discharge applications in which addition of chemicals, and
the inevitable build-up of residual concentrations would adversely affect the effluent quality or inhibit its
reuse.  Other applications of the ACE Separator™ are foreseen for the remediation of groundwater and
leachates (metals, COD/BOD removal), for enhancement of clay separation from aqueous chemistries
used in soil-washing operations, for the breakage of oil-in-water emulsions produced in the pumping of
hydrocarbon-contaminated groundwater and for removal of suspended solids from storm water runoff.
Industrial applications are envisioned for fine-grained product recovery (pigments, PVC) and for
extraction of suspended solids from waste streams which contribute to high BOD and COD loadings and
thus reduce POTW discharge surcharges. Overall treatment operating costs are nearly equivalent to
those for traditional chemical treatment; refinement in the engineering design of the electrodes and
process control mechanism are expected to further reduce these costs and thereby enhance the
economic attractiveness of this innovative treatment technology.


                  David M.  Rue and Robert Kelley
                   Institute of Gas Technology
                        3424 S. State St.
                        Chicago,  IL 60616
                  (312)  567-3711,  (312)  567-3809

                       Annette M. Gatchett
                  U.S. Environmental Protection Agency
              Risk Reduction Engineering Laboratory,
                  26  W.  Martin Luther King Drive
                   US EPA Cincinnati, OH 45268
                          (513)  569-7697


     The Institute of Gas Technology  (IGT) Fluid Extraction-
Biological Degradation  (FEED) Process extracts hydrocarbon
contaminants from soil and then biologically degrades the
pollutants in aerobic bioreactors.  The FEED process has the
potential to be an environmentally benign means of  safely and
economically degrading pollutants by overcoming bioavailability
limitations of the pollutants in  soil.  The process consists of
three stages; extraction, separation, and biodegradation.
Contaminants are first removed from the soil by solubilization in
supercritical carbon dioxide in an above-ground extraction
vessel.  The hydrocarbon contaminants are then collected in a
separation solvent, and clean CO? is recycled to the extraction
stage.  Separation solvent containing the organic wastes is sent
to the biodegradation stage where the wastes are converted to
CO2,  water,  and biomass.   All stages of the FEED process have
been successfully demonstrated.
     The extraction stage of the  FEED process relies on the
unique properties of supercritical .fluids (SCF) to  remove organic
contaminants from soil.  An SCF is a compound at conditions
exceeding its critical temperature and pressure.  Fluids in the ••'
supercritical range have viscosities and diffusivities between
liquids and gases with densities  close to those of  liquids.
Supercritical fluids have the solution characteristics of liquids
with better mass transfer capabilities.  Extraction and
separation are easily controlled  because changes in the pressure
(density) of an SCF can be used to change the solvation ability
of the fluid (1).
     Different compounds and classes of compounds have varying
degrees of solubility in individual SCFs.  Hydrocarbon compound
solubilities in supercritical CO2 as a general rule decrease with
increasing molecular size and with increasing aromaticity (2).
Alkanes are highly soluble, in supercritical CO2/  and larger
molecules as diverse as phenols,  pesticides, PCBs, dioxins, and
coal tar residues have been extracted from soils with
supercritical CO2.

     The biodegradation stage of the FEED process uses an aerobic
bioreactor.  In studies reported here an aerobic, PAH degrading
mixed-culture derived from contaminated soil was used.  The
bacterial cultures used for biodegradation at a specific site
will be selected based on site-specifics of the particular

METHODOLOGY                              ..  -   .

     The soil used for testing the FEED process was collected and
provided to IGT by Biotrol, Inc. (Chesha, MN).  Three soil
samples were taken by Ebasco from the North Cavalcade Superfund
Site in northeast Houston, Texas near the intersection of
interstate 610 and U.S. highway 59.  Biotrol mixed the three
samples and generated a composite sample which was sent to IGT.
The site was a wood preserving business, and the principal
pollutants are polynuclear aromatic hydrocarbons (PAHs) present
in creosote used as the wood preservative.  The soil was. stored
frozen at IGT until needed.  Analysis of the composite soil
labeled FEBD-1 by EPA method SW-846, 8100 revealed a total of
1925 ppm of PAH compounds.  This includes 50 ppm of 2-ring, 1132
ppm of 3-ring, 670 ppm of 4-ring, and 73 ppm of 5-6 ring PAHs.
     Extraction tests were performed in a batch supercritical
fluid extraction (SFE) unit purchased from LDC Analytical, Inc.
and modified at IGT.  Three 316 stainless steel vessels; a 55 ml.
extraction cell and two 150 ml separation vessels, are connected
in series and have individual pressure regulators and heaters.  A
metering pump with head chiller supplies CO2 to the system.
     Before each extraction test, 35 grams of soil is placed
between inlet and exit screens in the extraction cell.  Methylene
chloride is placed in the separation vessels.  The extraction
cell is pressurized with supercritical CO2,  and the separation
vessel pressures are set at 500 and 200 psig, well below the
critical pressure of CO2.   The extraction cell temperature is
then set.        •
     Extraction of contaminants begins when supercritical CO2 is
passed through the extraction cell.  After leaving the extraction
cell, the CO2 passes through an on-line UV spectrophotometer and
the two separation vessels.  Contaminants are collected in the
separation solvent and the scrubbed, depressxlrized CO2 is vented
from the unit through an activated carbon filter.  The fluid flow
is continued until the desired fluid to contaminant ratio is
reached.  After a test is completed, both the extracted soil and
the separation solvents are analyzed.
     All biodegradation tests were performed in batch mode in
clean 1000 ml Erlenmeyer flasks containing 250 ml of Basal Salts
Medium (BSM).  FEBD-1 soil extracts in ethanol  (2.5 ml) were
added to the flasks.  A 250 ul of 0.1 OD at 550 nm bacterial
suspension was added to the flasks which would give about 105
cells per ml.  The flasks were incubated at 30°C on a rotary
shaker operating at 150 revolutions per minute throughout the
experiment.  Triplicate or duplicate flasks we're sacrificed at

each sampling time to monitor bacterial numbers as measured by
viable cell counts, biomass as measured by protein content, and
residual PAH levels.  Bacterial cell counts were performed using
the drop plate method (3).  Biomass was measured as ug of protein
per ml of culture using a protein assay kit by Pierce Chemicals.

RESULTS                                             '

     More than twenty supercritical carbon dioxide extraction
tests have been conducted with sample FEBD-1 in the lab-scale SFE
unit.  The base test conditions were 2000 psig at 115°F using a
CO2 to contaminate ratio of 6800 Ib/lb and no methanol additive.
These four operating variables were changed in the test matrix.
     When the extraction pressure was 2000 psig and the
temperature was 90, 115, and 170°F,  the highest extraction levels
were achieved at 115°F.   Extraction of 2 to 6 ring compounds
increased from 90.6 percent at 90°F to 93.7 percent at 115°F and
declined significantly to 79.3 percent at 170°F.   The largest
declines in extraction levels at high temperature were for the
heavier 4 to 6 ring compounds.
     The effect of the ratio of carbon dioxide to contaminants on
extraction levels was studied with ratios of 2200 to 12300 Ib/lb.
Extraction levels of 2 to 6 ring compounds increased from 84.2
percent at 2200 Ib/lb to 93.7 percent at 6800 Ib/lb.  No increase
in extraction was obtained with higher CO2/contaminant ratios.
     Pressure effects on extraction were studied between 1100 and
4000 psig, all in the supercritical range.  The results of tests
conducted with and without 5 weight percent methanol added as an
extraction modifier are summarized in Table 1.


Test              E-5     E-4     E-3     E-6    E-12    E-13
Pressure; psig   1100    1500    2000    2000    4000    4000
Methanol, %         0       00       5       0       5
PAH Removal, %
Naphthalene      99.2    97.8    98.7    98.2    99.4    98.5
Phenanthrene     97.0    97.9    98.0    97.8    98.1    98.8
Benzo(a)pyrene   78.0    81.4    78.9    93.1    90.4    93.7
2 Ring PAH       99.2    97.8    98.7    98.2    99.4    98.5
3 Ring PAH       96.7    97.4    97.3    97.5    97.4    98.6
4 Ring PAH       90.0    91.9    90.9    97.2    96.2    97.1
5-6 Ring PAH     52.1    53.5    58.2    90.6    70.4    84.3

Total PAH        92.6    93.8    93.7    97.2    96.0    97.5

     Extraction levels increase with increasing pressure between
1100 and 4000 psig.  The largest extraction increases are
obtained for the heavier 4 to 6 ring compounds.  Adding 5 weight
percent methanol to the extraction CO, significantly increases
the extraction levels.  The greatest increases are again for the

heavier 4 to 6 ring contaminants.  A comparison of contaminant
levels in the soil after extraction using CO2 with and without
the methanol additive is presented in Figure 1.  Total
contaminants in the soil are reduced from 1925 to 50 ppm using
carbon dioxide with 5 percent methanol.
     The biodegradation of PAHs present in supercritical extracts
of FEBD-1 soil is presented in Figure 2.  The cells used for
biodegradation were pregrown in naphthalene and phenanthrene and
were washed thoroughly in BSM before inoculation.  After a lag
period of 40 hours, the total PAHs concentration reached a
treatmentendpoint of 52 percent of the initial concentration in
30 hours.  The same trends are evident with 2 through 6 ring PAH
     In a second series of similar batch experiments, the lag
period observed in the earlier experiments was eliminated by
pregrowing the culture in an ethanol Soxhlet extract of FEBD-1
soil.  Growth, as measured by protein content or bacteria
numbers, indicates that there is no increase in cell numbers due
to the presence of supercritical extract containing PAHs.
However, there is a significant increase in the protein content
due to the presence of supercritical extract.


     All three stages of the FEED process; extraction,
separation, and biodegradation have been studied in batch
reactors on the laboratory scale.  Supercritical carbon dioxide
extraction at 2000 psig and 115°F successfully removed more  than
93 percent of 2 to 6 ring PAHs from a contaminated soil.  The
addition of 5 weight percent methanol as an extraction modifier
increased the extraction levels to more than 97 percent and
enhanced particularly the removal of heavier 4 to 6 ring PAHs.
     The concentration of PAH compounds extracted with
supercritical CO, was  decreased by 53  percent in a bioreactor
after a 40 hour lag time and a 30 hour incubation time.  The lag
period was eliminated by pregrowing the bacterial culture in an
ethanol extract of the FEBD-1 soil.


1.   McHugh, M. and Krukonis, V.  Introduction.  In:
     Supercritical     .Fluid Extraction, Principles and Practice.
     Butterworths, 1988.

2.   Francis A  Ternary Systems of Liquid Carbon Dioxide.  J,
     Phvs-    Chem.  58: 1099-1114, 1954.

3.   Hoben, H.J. and Somasegaran, P.   Comparison on the Pour,
     Spread, and Drop Plate Methods for Enumeration of iRhizobium
     Spp. in Inoculants Made From Presterilized Peat.  Appl.
     Environ. Microbiol.  44: 1246-7,  1982.

2 Rings
3 Rings
4 Rings
5-6 Rings
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2-fing | 50
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5-6 ring I 73
total 1925
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1 1 1 1
  20    40    60    80    100    120
        Concentration in Soil, ug/g

CO2, 2000 psig        IHH CO2/MeOH, 2000 psig

CO2, 4000 psig        HI CO2/MeOH, 4000 psig
Temperature • 115 F
CO2/Contaminants • 6700 Ib/lb
CO2/MeOH - 95 % CO2, 5 % Methanol
40    60     80
      TIME, hours
        TOTAL PAHs

        4 RING
         2 RING

         5 & 6 RING



                               Robert W.  Hi Tiger
                  Superfund Technology Demonstration Division
                     Risk Reduction Engineering Laboratory
                     U.S.  Environmental Protection Agency
                            2980 Woodbridge Avenue
                           Edison, New Jersey 08837          ..        .   ,


      Cleaning up sites contaminated by releases from leaking underground
storage tanks (LUSTs) has  become a priority issue for EPA as the gap between
known releases and sites remediated continues to widen.  Nowhere is this gap
more prevalent than on the Native American reservations in this country.  In
most States it is common to see mounds of contaminated soil being removed from
service stations; old rusty tanks being removed and new tanks being installed.
These activities are promising signs that owners and operators of UST/LUST
facilities are trying to comply with the Federal and State regulations.
Unfortunately, such common occurrences outside the reservation are uncommon

      This problem is primarily attributed to jurisdiction in that most of the
funds that support UST/LUST activities are being channeled into State programs
which employ anywhere from 10 to 50 employees.  These programs are not
responsible for managing or implementing UST/LUST regulations on Native
American lands.  Although  the Indian lands represent a small percentage of the
National UST population, a unique situation is created whereby only one or two
Federal employees are responsible for overseeing and enforcing the Federal
UST/LUST regulations from  regional offices.  Region 9, for example, has only
one FTE (full time employee) to manage the UST/LUST activities on reservations
in California, Arizona, New Mexico, Nevada, and Utah.  Clearly, this is a
difficult if not an impossible task.           ,

      Recently, however,   a few programs are being established within some of
the Tribal governments to  address LUST issues and ensure compliance and
enforcement. The first steps taken in tackling the LUST issue was the
development of an UST/Lust tracking and prioritization system for managing
sites and ensuring that those sites which pose the greatest environmental
threat are addressed first.  The system would be utilized by both the US EPA
in Region 9 and by Tribal  authorities on different reservations.

SYSTEM DESIGN                              ;
                                                                              ' i

      The new system, named RUST! (Reservation UST Information), was developed !
by the Risk Reduction Engineering Laboratory and the EPA Region 9 UST/LUST
program.  RUSTI enables users to manage all UST related activities using a PC*.
The system was written in  Clipper V. 5.01 with several functions coded in
Microsoft C.  These languages offer considerable flexibility in operating
system environments (eg. LAN, stand-alone PC, multi-user PC) as well as
allowing for easy modification of the code.

      LUST sites involve enormous amounts of file review and paperwork; RUSTI
greatly simplifies and automates this "paper trail" by means of a customized,
electronic filing system and database.  Key UST/LUSt information is stored and
presented in the system in an easy to use and comprehend manner.  For examplei
if an individual needed to access information on a particular site, one could
access RUSTI and pull up a comprehensive file that illustrates all previous
activities (ie:  tank removals, site assessments, etc.) conducted at that
site.  Even an individual not directly involved with the site could quickly
understand the previous actions which occurred there; answer site-related
questions or make an educated decision as to the next logical step of
remediation.                                                            ,

      A set protocol established by the Regional office dictates the kind of
information needed to manage UST/LUST sites from new installations through
tank removals and closure.  The following UST/LUST activities represent the
bulk of their program:

         Tracking UST/LUST Notification Forms
         Oversight of UST Removals and Site Assessments
         Enforcing Leak Detection Requirements
         Managing Financial Responsibility
         Evaluation of Corrective Actions for Site Remediation
         Technical Support to Owners and Operators
         Compliance and Enforcement of Federal Regulations

      These activities are stored in three primary files, each file related  irt
some way to each other.  These files are:

      TRIBE:  Tribe name/code
              Associated correspondences

      SITE:   Site specific information
              Owner/operator information                                     .
              Tracking information
              Prioritization information
              Narrative sections

      TANK:   Site tank information

      All of these files are accessed either directly or indirectly via the  .
user  interface of the system.  RUSTI  is tailored in such a way that user£ can
make  quick assessments of the above activities within any of the three primary
files with just a few simple key strokes.  For example:  If the User were to
receive a telephone call requesting information about a site on the Nav^jO
Nation, the user would search the "Tribe" files under Navajo.  Other tribes
on-line would be filtered out, and the user would be presented a list of sites
which reside  on the  NAVAJO  nation..

      Additional searches can be made on any field which exists in any of
related databases previously mentioned.  These searches can then be combined
using "AND" or "OR" conjunctions and  the results displayed as in any simple
search.  Such search mechanisms, which are currently being used in many large
and  small scale database systems, provide unlimited flexibility in tailoring at
search to meet any users' needs.

      After  performing  the  search  and  selectively filtering  it using "AND" or
 "OR" combinations,  one  or more  records are  presented which adhere to the
 search criteria.  The user  then selects the site of interest by scrolling
 through a  list of sites.  The Site Information Screen  (see Figure 1) is then

                                NAVAJO  - SITE #3
       Name: Chevron  -  St.  Michaels
    Contact: Dan  J. Gallagher
     Add  1: AZ State Highway  264
     Add  2:
    City/St: St.  Michaels       AZ
     Chevron USA, Inc.
     Dan J. Gallagher
     PO Box 2833
     1300 South Beach Blvd.
     La Habra          CA
     90632-2833  (213)694-7903
                   RP         EPA
    Notific. Form:
    Removal Noti.:
    Removal Appr.:
      UST Removal: 05/01/87
    Confirmed Rel: 05/01/87
    LUST Resp Let:
    Site As. Recv: 12/13/89
    RP Workpl Rec: 10/11/90  04/18/91
     Remed. Init.:
     Remed. Compl:
    Site Clos App:
   Installation (Y/N):
      Operation (Y/M):
        Closure (Y/N):
    Abandonment (Y/N!):

Subst. Rel.: GASOLINE
  Qty. Rel.: UNKNOWN

Violation (Y/N): N
EPA Enforcement:
         EPA PM:
  Class: 3    No. Tank Records: 5    Groundwater Cont.: YES   Soil Cont.: YES
Enter , , , , , , 

, , or ? Figure 1 This screen display gives the user a comprehensive account of the Site activities, dates of correspondence, EPA approvals, release information, soil and groundwater contamination data, telephone numbers and addresses of owners/operators, classification rating and violation information. A variety of selections are available at the bottom of the Site Information Screen that pull up other files relevant to the Site selected. For example: if the user was interested in searching information on the types of tanks and contents stored at the example Navajo Site, they would select <"T"> and tank screen information would be displayed (see Figures 2 and 3). In addition RUSTI allows users to enter and edit specific site information into narrative files using standard word processor functions. By selecting on the site information screen (figure 1), the user accesses a menu for the narratives which include: (1) General information, (2) Site characterization, (3) Effects, (4) Corrective actions, (5) Operational considerations, (6) Enforcement, (7) Accounting information, and (8) Circuit Rider notes. These narrative "notepads" provide the user with a mechanism for managing and documenting all UST/LUST activities beyond the basic Regional protocol. 196

                          NAVAJO -   SITE   #3
Add 1
Add 2

: Chevron -
St. Michaels
: Dan J. Gallagher
: AZ State
Highway 264

: St. Michaels AZ


Select tank record
Chevron USA, Inc.
Dan J. Gallagher
PO Box 2833
1300 South Beach Blvd.
La Habra CA
90632-2833 (213)694-7903
to view/edit
Const. Mat. Rel.
                                Figure 2
                   NAVAJO - SITE # 3 - TANK # 1
Confirmed Release (Y/N): Y
          Tank Capacity:
Installation Date:  01/03/80
     Removal Date:  05/01/87
           Material of Construction: STEEL, SINGLE WALL
                      Tank Contents: PETROLEUM
               Corrosion Protection: UNKNOWN
                             Piping: UNKNOWN
                          Ownership: PRIVATE/CORPORATE
                         Compliance: INVENTORY RECONCIL.
          Overfill Protection (Y/N): Y
                      Upgrade (Y/N): Y
     Financial Responsibility (Y/N): N

During the transfer of hydrocarbon product from one tank to another
for the installation of cathodic protection equipment, inattentive
workers allowed approx. 200 gallons to spill into the subsurface.
                                Figure 3

      The prioritization algorithm utilized in this system provides a
methodology for site ranking using a variety of site characteristics.  These
characteristics are determined by posing a series of questions for the site.
Several answers are available for each question with each answer having a
different point value.  These values are summed and a classification number is
determined from this total.  Ten questions are provided and are as follows::   :

            Soil contamination (Y/N)
            Volume of soil contaminated
            TPH level in situ soil
            TPH level in stockpiled soil
            Groundwater contamination (Y/N)
            Free product on groundwater
            Contamination near domestic well
            Contamination near municipal well
            Benzene concentration
      •     Health / environmental risk (Y/N)

      A classification scheme was developed which associates a class number to
the site based upon the point summation from the above questions.  The classes
are summarized as follows:
Class 1
Class 2
Class 3
Class 4
Class 5
Class 6

This is the most severe classification which represents
significant human health and environmental risk.

This is the second most severe classification which represents
significant soil and groundwater contamination.  TPH levels in
soil exceed 2000 ppm and free product contamination is near either
municipal or domestic wells.

This class represents significant soil contamination and low level
groundwater contamination.  Groundwater contamination is not in
the proximity of municipal/domestic wells.

This class indicates soil contamination that requires remediation.
No groundwater contamination is present at this site.

This is the least severe classification denoting minimal soil
contamination and no groundwater contamination.

Insufficient/incomplete prioritization information.
      A centralized computer tracking and prioritization system serves as a
powerful and versatile tool for users that must deal with the remediation of a
large number of UST/LUST sites.  RUSTI provides considerable information at
the touch of a keystroke on all UST/LUST activities on Native American Lands
and classifies the sites based on potential and real environmental risk.  More
importantly, RUSTI provides the users with up-to-date information so that the
likelihood of work duplication is minimized both in the Regional offices and
in the Tribal governments.


      RUSTI also provides a standard reference structure to EPA and Native
American personnel not familiar with UST/LUST operating protocols.  By
prompting for data in a systematic format, users are made aware of what site-
related questions should be asked.  They are also reminded if critical site
information is missing from a given site file.  The system generates reports
and statistical information required by the Program Office quickly,
efficiently, and with a high degree of accuracy.  RUSTI may not be the answer
to the limited staff assignments that are responsible for the Native American
lands, but it does help EPA arid Tribal authorities maximize their efficiency
and productivity when cleaning up UST releases.


                                       Patricia M. Erickson
                                            U.S. EPA
                              Risk Reduction Engineering Laboratory
                                     5995 Center Hill Avenue
                                     Cincinnati, Ohio  45224

                              Robert L Einhaus and Issa Honarkhah
                                   Technology Applications,  Inc.
                                  26 W. Martin Luther King Drive
                                     Cincinnati, Ohio  45268
                                         (513) 569-7415
        Pdychlorinated biphenyl (PCB) contamination is a major concern at many sites across the
country, including more than 10% of the Superfund sites for which Records of Decision are available.
Under the Toxic Substances Control Act, material containing more than 50 parts per million (ppm) PCBs
must be treated by incineration (or equally effective treatment) or disposed in a chemical waste landfill.
Chemical destruction techniques equivalent to incineration have been the subject of numerous research
projects over the past 10-20 years.  High cost is the main disadvantage of conventional remediation
techniques; siting of both incinerators and landfills is becoming an additional obstacle.

        Liquids and sludges that contain PCBs are often solidified to improve waste handling
characteristics prior to remediation.  Solidification usually involves the addition of an alkaline material,
such as quicklime (calcium  oxide, CaO) or cement kiln dust.  In the  course of such bulking operations,
EPA staff noted an apparent reduction in  PCB levels following solidification, which might be attributable
to dilution during treatment, vapor phase  emissions, decomposition, or incomplete extraction of PCBs
from the solidified matrix prior to analysis.

        A laboratory study on this process commissioned by EPA yielded a draft final report in which the
principal investigator concluded that quicklime could completely destroy PCBs.  Reviewers determined
that the experiments and results described in the report did not justify the conclusions.  Therefore, EPA
began a study to repeat and expand the initial study, as well as to confirm field observations (1).
       The basic experimental approach was patterned after the experimental design us5ed in the initial
laboratory study conducted for EPA1.  A stock solution containing 1330 milligrams per liter (mg/L) 3,5-
dichlorobiphenyl (DCBP), 1050 mg/L3,3',5,5'-tetrachlorobiphenyl (TCBP), and 1330 mg/L 2,2'4,4',5,5'-
hexachlorobiphenyl (HCBP) were prepared in methylene chloride/methanol solvent. The stock solution
was used to spike a matrix comprised of equal-weight parts of diatomaceous earth, silicon dioxide and
     Reference 1 includes experimental details and the draft final report on the initial laboratory study.

acid-washed Ottawa sand. Replicate 50-g samples of the matrix were prepared, spiked with 50 mL of
the PCS stock solution, and allowed to dry at ambient temperature or at about 80 °C on a hotplate,
yielding matrix contaminated at 1330 ppm DCBP, 1050 ppm TCBP, and 1330 ppm HCBP.

       A series of open-vessel tests were conducted in which each of 10 PCB-spiked samples was
mixed with 120 g quicklime (91.4% CaO by Ca content).  At the start of the test, 50 mL reagent grade
water was added to each sample with vigorous manual stirring to  promote lime slaking (hydration), a
strongly exothermic reaction.  After cooling to <100°C, water was added to the treated mixture to
produce a thick slurry; the beaker was covered with a watch glass and the slurry was heated at 80-90°C
for 3 hours  (h), then left at ambient temperature.  Duplicate samples were acidified and prepared for
analysis at nominal times of 5-72 h after lime slaking.  In addition to the treated samples, 5 control
samples were prepared exactly as  described, with the exception that no quicklime was added.

       A series of four 24-h closed-vessel tests was performed in which 50-g PCB-spiked samples were
treated with  120 g alkaline material and a solvent.  The alkaline materials used in three tests were
quicklime, kiln dust, and an equal-mass mixture of the two, each slaked with 50  mL water. The fourth
experiment used quicklime slaked with 50 mL water/methanol (9:1 volumetric).  The reaction was carried
out in a resin reactor, fitted to connect a mechanical mixer, a thermocouple, a slaking-solvent reservoir,
and a solvent-trap system to collect volatiles and particulates emitted during the reaction.  At the start of
each experiment, the vessel was charged with  a well-mixed sample of PCB-spiked matrix and dry
alkaline material. After connecting the lid, a slight vacuum was drawn at the end of the solvent trap
(cold trap and bubbler). The slaking solvent was added to the dry mixture and stirred mechanically,
while vapor temperature and steam evolution were monitored. After slaking appeared complete,  the
treated mixture was allowed to cool, then slurried and heated as described for the open-vessel tests.

       Acidification of the treated mixtures with 7.2 molar hydrochloric acid was used to terminate any
reaction between hydrated lime and PCBs. Control samples received 600 mL water instead of acid.
After settling, the aqueous layer was decanted. The solid residue underwent three sequential
extractions,  using methanol, 50% methanol/50% methylene chloride, and methylene chloride.  After each
solvent addition, the mixture was sonicated and then centrifuged.  All solvent phases were combined
with the aqueous layer in a separatory funnel, shaken and allowed to separate.  The methylene chloride
layer was drained through sodium sulfate and diluted quantitatively with additional solvent.  Analysis was
performed by gas chromatography/mass spectrometry (GC/MS). The. overall method performance on
PCB-spiked matrix samples carried through the extraction and analysis procedure was 87.3-93.1%
recovery of the three congeners at relative standard deviations of 1.5-2.0%.

       A field sample was obtained from a site where lime solidification was applied to PCB-containing
sludges. The sample was homogenized, then  portions were acidified and extracted as described above.
Additional portions were extracted by the Soxhlet method (EPA Method 3540) using methylene chloride.
The extracts from both methods were subjected to additional florisil and gel permeation chromatography
to remove interfering constituents. Cleaned  extracts were analyzed by gas chromatography on a fused
silica capillary column followed  by electron capture detection.


Open-Vessel Tests

        Open-vessel tests showed large losses of PCBs following the addition of quicklime and water
 (Table 1). The greatest incremental decrease in concentration was observed at a  nominal reaction time
 of 5 h, immediately following the heating induced by quicklime slaking and subsequent heating on a
 hotplate. As soon as water was added to the  spiked matrix/quicklime mixture, the temperature rose to a

 maximum of 171-189°C and a particulate-laden steam column emanated from the beaker, suggesting
 that vaporization or steam stripping could be occurring. A substantial fraction of the DCBP loss in
 treated samples can be attributed to vapor losses, since the control (no quicklime) samples also showed
 high losses of DCBP.  The control samples showed much lower losses of TCBP and HCBP, indicating
 that these congeners have lower vapor pressures in the temperature range from ambient to 90°C.
 TCBP and HCBP losses in the treated samples could be due to vaporization and/or steami stripping at
 the higher temperature attained during quicklime slaking, as well as decomposition.
Table 1.
Percent PCB content remaining* at various times in open-vessel tests.
    Values for treated samples are averages of two; controls were not duplicated.

       Extracts of the quicklime-treated materials were analyzed for possible PCB decomposition
products.  Tentative identifications were based on comparison of measured mass spectra with library
spectra of known compounds. Concentration estimates were based on a response factor for each
product equal to that of deuterated chrysene.  Products included lesser-chlorinated biphenyls (mono-
penta congeners), and chlorinated biphenyls in which a methoxy or hydroxy group was substituted for
one chlorine. In addition, tetrachlorodibenzofuran (TCDF) was observed in all treated samples at
concentrations ranging from 1 to 14 ppm (0.07-1% of starting HCBP concentration).  This is the only
product where a response factor was calculated for the pure compound; a response factor of 0.359
relative to deuterated chrysene was calculated.

       Total product concentrations were estimated  to range from 12 to 229 ppm, with a striking
dependence on how the spiking solvent was removed from the sample prior to treatment.  In four
samples that were evaporated solely at ambient temperature, cumulative product concentrations were 48
to 229 pprn; three of these four samples produced 205-229 ppm total products, 1-5 ppm TCDF, and
peak temperatures above 180°C. The remaining six samples were heated at about 80°C prior to
treatment to remove residual spiking solvent. These pre-heated samples yielded total products of 12-50
ppm, Including TCDF concentrations of 4-14 ppra  It  appears that the presence of residual spiking
solvent favors formation of all observed products except TCDF.

       Total product concentrations in the open-vessel samples after 5 to 72 h reaction times ranged
from 0.3-6% of initial PCB concentration. These products in no way account for the bulk of the absent
PCB mass.  Losses to the vapor phase were suspected, based on  DCBP loss in the control sample and
apparent temperature dependence of losses of each congener.  A wipe test of interior surfaces of the
glove box In which these experiments were conducted showed significant contamination by all three
congeners.  Modelling showed that the observed time-dependent loss of PCBs was consistent with

volatilization expected for Aroclor mixtures at the experimental temperatures.

Closed-Vessel Tests

       Closed-vessel tests were conducted to determine if PCB losses observed in the open-vessel
tests were, in fact, due to vapor-phase losses of the spiked congeners, and  not losses of decomposition
products.  The apparatus was under slight negative pressure to prevent vapor concentration buildup
above the reaction mass.  Four tests were carried out, each allowing 24 h reaction time after the addition
of alkaline material and water.  Test results are shown in Table 2.  Extracts prepared from the solids in
the reaction vessel and solvent in the cold trap were analyzed separately for residual PCB and
decomposition products.

Table 2.        Percent recovery of PCB congeners from closed-vessel tests after 24  h reaction time.
               PCBs from the solid matrix plus the cold traps are summed  to yield total  recovery.
Kiln dust
Quicklime/Kiln dust
50 + 17 = 67
84 + 3.9 = 88
102 + 3.5 =106
87 + 6.7 = 94
75 + 2.0 = 77
89 + 1.3 = 90
110 + 1.0 =111
102 + 1.0 =103
64 + 1.0 = 65
89 + 0.5 = 90
122 + 1.0 =123
87 + 2.5 = 90
    Water added to slake the lime was spiked with 10% methanol (v:v).

       This set of experiments yielded essentially full recovery of the spiked PCBs in three of the four
variations.  In the first experiment, using quicklime alone, some PCBs may have been lost due to vapor
emission through poorly-fitted thermocouple and stirrer ports, or due to incomplete extraction of solids
adhering to reaction vessel walls, lid and cold trap connections. Vapor or paniculate emissions are
consistent with increasing recoveries of all congeners observed as quicklime was replaced with kiln dust:
the temperature should have decreased as CaO content in the alkaline material decreased, thereby
decreasing the tendency of gaseous species to escape the vessel.  Temperature could not be measured
during the reaction, since the thermocouple interfered with the stirrer.

       Although the closed vessel tests were expected to yield higher total recoveries than the open-
vessel tests if vapor phase losses were dominant  in the latter, we expected higher recoveries of PCBs
from the cold trap  in the closed vessels.  At 24 h, open-vessel samples had lost 75-87% of the initial PCB
spikes, with less than 6% accounted for in reaction products. Closed-vessel tests yielded only 0.5-17%
of the initial spikes in the solvent traps at the same reaction time.  Vapor condensation and paniculate
deposition  on  reaction vessel surfaces were visually observed during the closed-vessel tests.  These
factors probably account for the apparent reduction in PCB volatilization but could not be quantified
separately from the bulk solid matrix. Another factor that may have contributed to reduced volatilization
is reduced  reaction temperature,  resulting from poorer mixing (thus slower slaking) or from lower CaO
concentration  in kiln dust (thus less heat of hydration produced).

Field  Sample

       A sample was obtained from a site where lime was used to solidify PCB-containing waste.
According to sample documents, a bucket of material had been taken after various wastes were
composited and solidified, and then stored on-site.

        The sample was homogenized and then sub-sampled as needed for analysis.  Four replicate
 samples were acidified and extracted using the same procedure applied to open- and closed-vessel test
 samples.  Two additional samples were extracted using the Soxhlet method.  Gas chromatography with
 electron capture detection (GC-ECD) was applied to cleaned extracts. Peak profiles were compared to
 Aroclor standards; the best agreement was found for a mixture of Aroclors 1242 and 125-1; equal mass
 mixtures of these Aroclors were then used for calibration to quantify the field sample extracts.

        The acidification/extraction procedure  yielded an average PCB concentration of 200 ppm with a
 relative standard deviation of 4.2% for four replicate samples. The Soxhlet procedure yielded 218 and
 222 ppm PCBs on duplicate samples.  Prior to treatment, samples taken at various locations across the
 field site were reported to contain up to 157 ppm PCBs.  The field sample analyzed  in this study snowed
 that the treatment did not destroy PCBs to any measurable extent. Although both extraction procedures
 successfully extracted PCBs in this study, the characteristic Aroclor pattern was completely indiscernible
 when extracts were analyzed by GC/MS, owing to interference by numerous other compounds extracted
 from the sample.  If an analytical  laboratory attempted to analyze PCBs by GC/MS techniques, heavily
 contaminated samples might result in non-detection owing to masking by other contaminants. GC-ECD
 Is less subject to these interferences.
       Addition of quicklime and water to PCBs on an inert matrix resulted in very little PCB
decomposition. Less than 6% of the starting material was identified in reaction products.  Products
found routinely included partially-dechlorinated biphenyls, hydroxy-substituted PCBs, and TCDF. The
variety of products was decreased and total concentration of products was less than 1.4% of starting
PCB content when heat was applied to remove spiking solvent prior to treatment. These heated
samples typically exhibited more TCDF than unheated samples, but lower concentrations and less
variety of other compounds.  Only the unheated samples yielded methoxy derivatives.

       Vapor-phase losses of PCBs were significant in open-vessel tests. The effect was temperature
dependent, with the dichloro congener quite susceptible to evaporation at 90°C or lower, and the other
congeners more subject to evaporation or steam stripping at higher temperatures.  High temperatures
were achieved by slow water addition and vigorous mixing.

       A stored sample from PCB-containing sludge solidified with lime was found to contain about 200
ppm PCBs as Aroclors 1242 and 1254. The PCB content was extractable by  both the
acidlfication/sonication/extraction procedure used in this study and the more conventional Soxhlet
extraction.  No conclusions can be drawn regarding previous reports of PCB losses since splits were not
reserved  of samples analyzed by other laboratories.

       Treatment of PCB-contamlnated materials by quicklime and water, as  performed in these
experiments, did not result in the degree of dechlorination required for remediation  of contaminated
(1)     Einhaus, R. L, Honarkhah, I., and Erickson, P. M.  Fate of Polychlorinated Biphenyls (PCBs) in
       Soil Following Stabilization with Quicklime.  EPA/600/2-91/052, U.S. Environmental Protection
       Agency, Cincinnati, Ohio, 1991,114 p.

                      TREATABILITY DATABASE

                        .  Glenn M.  Shaul

                (513) 569-7408 Fax (513)t 569-7787
               Chief, Chemical Engineering Section
                      Toxics Control Branch
      Water and Hazardous Waste Treatment Research Division

1.   Purpose

The purpose of the RREL Treatability Database is to provide a  ,
thorough review of the removal/destruction of chemicals in
various types of media, including water, soil, debris, sludge and
sediment.  There are currently thirty-three treatment
technologies, thirteen aqueous matrices and five solid matrices
presented in the database.  Version 4.0 was released in January
1992 and is free of charge.

2.   Target Group

     The users of the database include federal, state and local
governments, universities, industry and consulting engineers.
These diverse groups share a common interest in needing reliable
treatability data for specific chemicals of environmental
interest.  Current distribution is approximately 1500.

3.   Organization

     The program contains physical/chemical properties for each
compound, as well as treatability data.  The treatability data,
summarizes the types of treatment used to treat the specific
compound; the type of waste/wastewater treated; the size of the
study/plant; and the treatment levels achieved.  In addition,
each data set is referenced with respect to source of information
and each reference is quality-coded based upon analytical
methods, reported quality assurance and quality control efforts
and operational information on process(es) sampled.

4.   Computer Hardware and Software

     The requirements are as follows:   IBM personal computer or
compatible; 8 megabyte hard disk storage; 640 K RAM memory; DOS
version 2.0 to 5.0, except version 4.0; and a 12 pitch printer.
The program has been compiled and does not require any
specialized software to operate it and it is menu driven for ease
of use.  The program can also be accessed through EPA's
Alternative Treatment Technology Information Center (ATTIC).
Please contact Joyce Perdek at 908-342-4380 for additional


     Rakesh Govind, Chao Gao,  Department of Chemical Engineering,  University of
                  Cincinnati, Cincinnati, Ohio  45221  (513)  556 2666
        Henry H. Tabak, U.S. EPA, RREL,  Cincinnati, OH 45268 (513) 569  7681


       Mixed substrate systems  are often  encountered  in pharmaceutical, food,
 wastewater processes and chemical manufacturing industries.  In  wastewater treatment
 systems, a number of organic compounds are present at the same time.  In these cases
 it is inevitable that the toxic, or  inhibitory substrates will be found  in mixtures with
 nontoxic,  or conventional wastes.   In the presence of alternative carbon sources, a
 number of possible substrate interactions can occur.   Extensive studies on
 biodegradation of single components have been  conducted  (1).  However,  there is
 insufficient information on the performance of biological treatment facilities for the
 removal of a specific chemical from wastewater, consisting of a mixture of organic
 pollutants.  There is a strong need for extensive  studies of  multisubstrate systems.  A
 broad data  base will help to understand the interaction and  removal rates of organic
 compounds in  mixtures. These studies  will also  help to establish  control mechanisms
 that regulate the relative utilization rates of mixtures.  In this paper, emphasis will be
 given on  a comprehensive  review of mechanisms, experimental methods, and
 modeling  studies  for  biodegradation of mixed  substrates.

       In biological treatment plants,  the substrate removal  pattern in  a  multisubstrate
 system may include simultaneous, preferential,  or sequential  utilization.   The diauxi'c
 growth observed by Monod (2) in Escheiichia coli suggests  that the very presence of a
 particular  substrate  in  a  wastewater stream   might  prevent  an   organism  from
 acclimatizing to another substrate until the first one has been  completely  metabolized.
 The blockage of metabolism of  one compound by another may lead to preferential  or
 sequential  substrate  removal from a multisubstrate environment.  Chian and  Dewalle
 (3) have presented evidence for the  sequential removal of  waste components during
 biological  treatment of a leachate from a sanitary landfill.  Deshpande and Chakrabarti
 (4), in a batch  reactor, demonstrated preferential  removal of  m-nitrobenzenesulfonate,
 sodium salt (m-NBS),  from  a mixture of m-NBS  and resorcinol,  compounds  that  are
 known to be present  in m-aminophenol (m-AP) manufacturing wastewaters,

      The  mechanism of substrate  utilization by a  bacterial cell  can  be generally
 described  as  a sequence of three  complex  processes: contact of  a cell  with the
 molecule of a  substrate; transport of the molecule into the cell; and  formation of the
 substrate  Intermediate.   On the basis  of this general mechanism,  it is  possible  to
 classify various types of  substrates into  three  main groups:  (a) single  components
 substrates, which  are  directly transportable; (b) multicomponent substrates, which  are
 represented by  a  mixture of several  single substrates;  (c)  complex substrates, which
 have to be changed externally prior to transportation into the cell.

      The specific research objectives  of  this  project are as follows:  (l)IEvaluate  the
 effect of  co-metabolites  on  biodegradation  kinetics;  (2)Develop  appropriate kinetic
data for organics with a variety of functional groups; (3)Develop appropriate kinetic
data of a  toxic organic  in  presence of multiple toxics from  homologous and  non-
homologous  series, as sole carbon source or in wastewaters containing  background
concentrations of biogenic  or toxic  organics; and  (4)Validate the  structure-activity

relationship model  for the biodegradation kinetics of the toxic compounds as single or
multiple components in a variety  of municipal / industrial wastewaters.


       Experiments were  conducted using a  12 unit VOITH electrolytic  respirometer for
the following mixed substrates: (1)Mixture of chemical and raw wastewater from the
primary effluent stream of a domestic  activated sludge treatment plant;  four chemicals
were studied at a concentration level of 100 mg/l :  Aniline, Catechol, Phenol and
Benzene.   (2)Mixture of chemical  and wastewater from the secondary  basin of a
domestic activated  sludge treatment  plant; four chemicals were studied  at a
concentration of 100 mg/l: Aniline,  Catechol,  Phenol  and Benzene.  (3)Raw wastewater
from the primary effluent stream  with no compound; and (4)Wastewater  from the
secondary  basin with no compound.

       The VOITH electrolytic  repirometer consists of a temperature  controlled
waterbath,  containing measuring  units,  an on-line microcomputer for  data sampling,
and a  cooling unit for continuous recirculation of waterbath volume.   Each measuring
unit consists of a reaction vessel, with the microbial inoculum and test  compound, an
oxygen generator, comprised of an electrolytic cell  containing copper sulfate and
sulfuric acid solution, and a pressure  indicator which triggers the oxygen generator.
The carbon dioxide  generated  is  absorbed by soda lime,  placed in the reaction flask
stopper.   Atmospheric pressure fluctuations  do not  affect the results since the
measuring  unit forms an  air  sealed system.   The uptake of oxygen by the
microorganisms in  the  sample  during biodegradation is compensated  by the
electrolytic generation of oxygen in  the oxygen generator, which is  connected to the
reaction vessel.  The amount of  oxygen supplied  by the  electrolytic cell is proportional
to its  amperage requirements, which is  continously  monitored by the microcomputer
and the digital  recorder.

       The nutrient  solution  used in  our studies was an OECD synthetic medium (5)
consisting  of measured  amounts  per liter of deionized distilled water containing  (1)
mineral salts solution; (2) trace salts solution;  and (3) a solution (150 mg/l) of yeast
extract as  a substitute  for vitamin solution.

       The microbial inoculum was an  activated sludge from The Little Miami
wastewater plant in Cincinnati, Ohio, receiving municipal wastewater.  The activated
sludge sample was  aerated for 24 hours before use  to bring  it to an  endogenous
phase.  The sludge biomass was added to the medium at a concentration of 30 mg/l
total solids.  Total  volume of the synthetic medium was 250 ml in the  500 ml  capacity
reaction vessels.  Reactor flasks either  contained 62.5 ml of  primary  effluent
wastewater mixed with  164  ml of deionized distilled  water or  125 ml  of  secondary
wastewater mixed with  101  ml  of deionized distilled water.

       In a typical  experimental run, duplicate  flasks were used for the  test mixture,
and reference compound (aniline).  The reaction vessels were incubated  at  25° C in
the temperature controlled  bath and stirred  continuously throughout  the  run.  The
microbiota of the activated sludge were not  preacclimated to  the substrate.  The
incubation period of the experimental  run was between 28-50 days.   A  comprehensive
description of the  procedural  steps  involved in the  respirometric tests  have been
presented  elsewhere (6).

       Kompala et al. (7) studied the cybernetic modeling  of microbial growth on
multiple substrates.  In this model,  the internal regulatory processes,  which underlie a
variety  of behavior in microbial growth on  multiple substrates,  are viewed «is a
manifestation of an invariant strategy to optimize some goal of the cells.  The model
proposed in this paper for describing the  degradation of multiple substrates is  based
on the  cybernetic model, and  allows the prediction of microbial growth behavior based
on growth data for single substrates.  The framework of this model  can be applied  to
batch or continuous culture growth  of several bacteria on different combinations  of

       In the sequential growth on multiple substrates,  the cells grow  first on the
fastest  assimilated substrate in the medium.  The  cells  may have acquired such  a
strong capability to optimize their growth  behavior in the  following manner:  Assume
that  in  a multisubstrate environment, there exist cells with different strategies of
responding  to the environment.  The cells  that arbitrarily choose  to grow first on the
fastest  substrate available  proliferate much faster  than the cells that  responded
differently.  Very quickly  all the cells that  remain in that environment will be those that
have responded in the most optimal manner.  Hence, it is reasonable  to  postulate  that
over many  years of evolutionary processes, in environments with varying menus of
substrates,  microbes have  acquired  the capability  to control their regulatory processes
to optimize their pattern.  The basic merit  of the cybernetic approach is that  it adopts a
mathematical simple description of a complex organism but compensates for the over-
simplification by assigning  an  optimal control motive to its response.

       The  microbial growth on  multiple  substrates can  be simplistically represented by
the following equation:
        B  + S|	   (1+Y,)B + Pr                      (1)
     where: B is the biomass excluding the key enzyme Er.
       Instantaneous maximum biomass productivity model was  proposed by  Kompla
(6).  This model  proposes that, in a multiple substrate  environment, at any instant t,
the organism  chooses  to synthesize the enzyme for the  substrate which  maximizes the
biomass growth rate at that instant.  The major limitations of the cybernetic model is
that it only predicts  an optimal allocation of existing resources to  the  enzyme
synthesis alternatives  .
       The cybernetic model equations for  biodegradation of multiple substrates  are
given  below:
                     e, S, C
                 K? K8f + S,

                 a, S) C


     dt    K?K8f + S,     dt
     dS,     !
     "dT - - Tt re''v'
                            (Ln C ) e, - p,e,
         max (rBJ)






 biomass concentration [ mg/l ]
 specific enzyme level
 ith key enzyme [ mg/l ]
 Michaelis constant [mg/l ] for pure compound i
  inhibition factor for Michaelis constant
 ith bioproduct [ mg/l ]
  rate of biomass production through consumption of S; [ mg/I/Hr ]
 rate of Ef synthesis [ mg/I/Hr ]
 ith substrate [ mg/l ]
   ith bioproduct concentration [ mg/l ]

     U|,     cybernetic model  variables

     V|     cybernetic model variables

     Y|    yield coefficient [ mg/mg ]

     Yp|    ith product yield coefficient [mg/mg]

     ctj     enzyme synthesis rate constant [1/1 ]

     Pi     enzyme decay rate constant [ 1/1 ]

     H°     growth coefficient [1/1 ] for pure compound i

     (if      inhibition factor for growth coefficient

       Note that the Monod equations in the  cybernetic model was modified to include
inhibition  from  other  substrates,  products  or biomass  as  initially proposed  by
Levenspiel  (8).

       The cybernetic  model equations were  used to obtain the kinetic parameters
from the cumulative oxygen uptake data obtained  for mixed substrate systems.


       Figures 1 through 4  show the cumulative oxygen uptake curves for aniline,
catechol, phenol  and  benzene in  clean  water, primary effluent and secondary effluent.
The oxygen uptake curve obtained for the wastewater  without the compound has been
shown for  comparison.

       Similarly, oxygen uptake  curves were obtained for binary mixtures of the four
chemical compounds  in clean water, primary  effluent and  secondary effluent.   Figure 5
shows the  oxygen uptake curve for a mixture of benzene and aniline  in clean water.
The cybernetic model  was applied using the  single compound  Monod parameters,  and
the calculated and  experimental  curve for clean water are shown in the Figure.  The
cybernetic  model parameters are summarized in Table  1.


       It has been  shown that the  Monod  kinetic  parameters obtained for the
degradation of single compounds in wastewater are statistically the same as those
obtained in  clean water.  This result  is significant, since most of the available Monod
kinetic parameters  in the literature, were obtained using clean water.   Furthermore, it
has been demonstrated that the oxygen uptake curves  for binary mixtures of
compounds  can be derived from single compound Monod kinetic parameters using the
cybernetic  model.   This allows  the prediction of biodegradation of compound mixtures
in clean water systems from single compound studies.  The extention of  this result for
dirty wastewater  is currently being developed.

1 . Tabak, H.H., Govind, R., Determination of biodegradation kinetics with the use
   of respirometry  for development of  predictive  structure-biodegradation
   relationship models,  Paper presented  at the ACS I&EC Division Special
   Symposium on "Emerging  Technologies for Hazardous Waste Management",
   Atlanta,  GA, 1991.

2. Monod, J.  Recherche suila croisceance des Cultures Bacteriennos; Hermann:
   Paris,  1942.

3. Chian, E. S. K.; Dewalle, F. B. Prog. Water Technol.  1975, 7, 235.

4. Deshpande, S. D.; Chakarabarti, T. Proceeding of the National  Symposium on
   Biotechnology; Jain, S. C., Ed.; Punjab University: Chandigarh,  India, 1982;  pp

5. OECD  guidelines for testing of chemicals.  EEC directive 79/831, Annex  V, part
   C: Methods for  determination of ecotoxicity, 5.2 Degradation, Biotic  degradation,
   Manometric respirometry, Method  DGX1, Revision 5. pp. 1-22, 1983.

6. Tabak, H.H., Govind, R., Determination of biodegradation kinetics with the use of
   respirometry for development of predictive structure-biodegradation  relationship
   models,  Paper presented  at the IGT Symposium, Colorado  Springs,  CO, 1991.

7. Kompala, D. S.;  Ramkrishna, D.; Tsao, G. T.,  Cybernetic   Modeling of Microbial
   Growth on Multiple  Substrates, Biotechnol. Bioeng., Vol. XXVI,  1272-1281,

8. Keehyun Han,   Levenspiel,  Octave,  Extended  Monod Kinetics for Substrate,
   Product, and  Cell  Inhibition, Biotechnol.  Bioeng., Vol.  32,  430-437,1988.
Table 1 Values for the  cybernetic model  parameters
             (For all substrates,  a; =0.001, (3j= 0.05, e10/e2o = 4.47/84.8)



                       100     150    200
                             TIME (HE)
  FIGURE 1.  Cumulative oxygen uptake curve for the following
  mixtures:  [1] Primary effluent  and aniline (100 mg/l); [2]  Secondary
  effluent and aniline (100 mg/I); [3] Clean water and aniline (100
  mg/i); Primary  effluent; [5] Secondary effluent.
              20    40   60   80   100   120   UO   160   180
                             TIME (HE)
FIGURE 2.  Cumulative oxygen uptake curve for the following
mixtures:  [1] Primary effluent and  catechol (100 mg/i); [2]
Secondary effluent and  catechol (100  mg/l);  [3] Clean water and
catechol (100 mg/l); Primary  effluent;  [5] Secondary effluent.

                    40   6°    8™r^°  12°   U°   16°   18°
                              TIME (HR)
                            80   100   120   UO   160  180
FIGURE 4.  Cumulative oxygen uptake curve for the following
mixtures: [1] Primary effluent and benzene (100 mg/I); [2]
Secondary effluent and  benzene  (100 mg/l);  [3] Clean water and
benzene (100 mg/I); Primary effluent; [5]  Secondary effluent.

                  10   15   20   25   30   35  40   45   50
FIGURE 5.  [1] Concentration of aniline varying as a function of
time, during the biodegradation  of a mixture of benzene and
aniline; [2]  Concentration of benzene changing as a function of
time, during the biodegradation  of a mixture of benzene and
aniline; [3]  Experimental oxygen uptake curve for a binary  mixture
of aniline and benzene; [4] Calculated oxygen uptake curve using
the cybernetic model; [5] Biomass concentration in COD units.
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