EPA/540/R-92/080
                                           December  1992
       SITE-Emerging Technologies:
  Laser Induced Photochemical Oxidative
Destruction of Toxic Organics in Leachates
            and Groundwaters
                  by
   Energy & Environmental Engineering, Inc,
      Research and Development Division
         Somerville, MA  02143
  Cooperative Agreement No.  CR 815330020
            Project officer

            Ronald F. Lewis
  Buperfund Technology Demonstration Division
     Risk Reduction Engineering Laboratory
            Cincinnati/ Ohio 45268
 RISK REDUCTION ENGINEERING LABORATORY
  OFFICE OF RESEARCH  AND  DEVELOPMENT
  U.8.ENVIRONMENTAL PROTECTION AGENCY
        CINCINNATI, OHIO  45268

-------
                            DISCLAIMER
     The information in this document  has  been  funded in part by
the United  States Environmental Protection Agency under Cooperative
Agreement No.  CR 815330020 to Energy and Environmental Engineering,
Inc. The document has been subjected to  the Agency's administrative
and peer review and has been approved for publication  as  an EPA
document. Mention of trade  names  or commercial  products does not
constitute endorsement or recommendation for use.
                                11

-------
                             FOREWORD
     The U.S. Environmental Protection Agency (EPA) is charged by
congress  with  protecting  the  Nation's   land,  air,  and  water
resources. As the enforcer of  national environmental laws, the EPA
strives to  balance human  activities  and  the ability  of natural
systems to support and  nurture life. A key  part of the EPA's effort
is its  research  into our environmental problems to  find new and
innovative solutions.

     The   Risk  Reduction  Engineering   Laboratory   (RREL)   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 the EPA with  respect to
drinking water, wastewater,  pesticides, toxic substances,  solid and
hazardous   wastes,   and   superfund-related   activities.   this
Publication is one of the products of that  research and provides a
vital  communication link between  the  researcher  and  the  user
community.

     Now  in  its  sixth year,  the  Superfund Innovative Technology
Evaluation  (SITE)  Program is  part of  EPA's research into cleanup
methods  for  hazardous waste  sites around  the nation.  Through
cooperative  agreements with  developers,  alternate  or innovative
technologies  are refined at  the  bench-and  pilot-scale level and
then  demrnstrated at  actual   sites.  EPA  collects  and evaluates
extensive performance data on  each technology to  use  in  remediation
decision-making  for hazardous  waste sites.

     This  reports  documents the results  of laboratory and pilot-
scale  field  testing  of  Laser  Induced  Photochemical Oxidative
Destruction  of toxic wastes in groundwater.  It  is  the first in a
series  of reports  sponsored   by  the  SITE  Emerging Technologies
Program.
                              E. Timothy Oppelt, Director
                              Risk Reduction Engineering Laboratory
                                ill

-------
                         ABSTRACT

Laser Induced Photochemical Oxidative Destruction of Toxic Organics
                           in Solution

Organic  compounds  and  specifically  chlorinated  aromatic  and
unsaturated organics are major contarainants in groundwaters.  These
latter species also tend to rank hxgh on the list of EPA priority
pollutants,  even  at the  low (ug/1) concentrations that  they are
normally found in groundwaters.  The technology described in this
report has been developed under the Emerging Technologies section
of the Superfund Innovative Technology Evaluation (SITE) Program to
photochemically oxidize organic compounds in wastewater by applying
ultraviolet  radiation  using an  excimer  laser.   The  photochemical
reaction  is  capable  of  producing the  complete destruction  of
moderate  to extremely low  concentrations  of  toxic organics  in
water.  The energy supplied by the laser  is  sufficient to stimulate
photochemical reactions between the organics  and hydrogen peroxide
employed  as a chemical  oxidant,   causing  photo-oxidation  and/or
phototransformation of the toxic species  to carbon dioxide,  water,
and the corresponding halogenated acid.  Additionally the radiation
is not absorbed to any  significant extent by the water molecules in
solution.  The process  has been developed as a final treatment step
to reduce organic  contamination in groundwater and industrial waste
waters to acceptable discharge limits.

Optimum  conditions  for  the  complete  destruction  of  several
different classes of compounds were developed and demonstrated in
the laboratory.

This  report  is submitted  in  fulfillment of cooperative agreement
number CR-815330-02-0  by Energy &  Environmental Engineering, Inc.
under  partial  sponsorship of  the  USEPA.   This  report  covers the
period from October 1988  to September  1990,  with the completion of
work  in September 1990.
                                IV

-------
                    TABLE OF CONTENTS

                                                            Page
Disclaimer                                                 ii
Foreword                                                  iii
Abstract                                                   iv
Figures                                                    vi
Tables                                                    vii
Acknowledgements                                         viii

I. Executive Summary                                        1

II. Introduction                                            2

III. Conclusions and Recommendations                        3

IV. Background Information                                  4

     A. Process Description                                 4

     B. Potential Applications                              7

          1. Introduction                                   7
          2. Superfund Sites                                7
          3. Industrial Waste Streams                       8

     C. Competitive and complementary Technologies          9
          1. Physical Treatment Processes                   9
          2. Chemical Treatment Processes                   10
          3. Biological Methods                             10
          4. incineration                                   11

V. Experimental Results                                     12

     A. Experimental Procedures                             12

     B. Initial Irradiation and Oxygenation Experiments     17

     c. Hydrogen Peroxide Results                           25

     D. Status                                              37

VI. Quality Assurance                                       42

VII. Evaluation of The LIPOD Process                        43

-------
                    LIST OF FIGURES

                                                            PAGE
1.    Process Flow Scheme                                      5

2.    Overall Reaction Chemistry                               6

3.    Impact of Irradiation Dose and Inlet Concentration on
     Extent of Reaction (Chlorobenzene saturated with air)   19

4.    Schematic of Test Facility for Non-Aerated Fluids       21

5.    Schematic of Aerated Recycle Apparatus                  22

6.    Process Flow Oxygenation Schemes                        24

7.    Destruction of Chlorobenzene by various Oxygenation
     Schemes                                                 26

8.    impact of Irradiation Dose on Extent of Reaction        28

9.    Impact of Hydrogen Peroxide Concentration on
     Reaction Rate                                           29

10.  Extent of Reaction During the Initiation Stage          31

11.  Impact of Irradiation on the Reaction Rate of
      Several Organics During the Propagation Stage          32

12.  Impact of Feed Concentration on Reaction Rate
     (Solution Irradiated at 1 Photon/Molecule)              34

13.  Impact of Feed Concentration on Reaction Rate
     (Solution Irradiated at 10 Photons/Molecule)            35

14.  The Impact of Irradiation Wavelength on the
     Destruction of Chlorobenzene                            36

15.  impact of Irradiating a Portion of the Fluid            38

16.  Destruction of M8W Waste Leachate                       41
                                vi

-------
                    LIST OF TABLES

                                                            PAGE

1.    Toxic Concentration and Absorbance                      15

2.    Ionic Species concentration and Absorbance              16

3.    Calculation of Maximum Extents of Reaction as
     Limited by Dissolved Oxygen                             18

4.    Batch Photolysis of Chlorobenzene Solutions
     Saturated with Air                                      19

5.    Destruction of Various Toxics by Laser                  30

6.    Semivolatile GC/MS Analysis of Real Waste  6/19         39

7.    Semivolatile GC/MS Analysis of Real Waste  6/28         40

8.    Operating Comparison of UV Oxidation Processes          44

9.    Cost Comparison of LIPOD to Other Toxic Organic
     Removal and Destruction Processes                       46

10.  Lipod cost as a Function of Capacity                    47
                               Vll

-------
                         ACKNOWLEDGEMENTS

This document was prepared under cooperative agreement number
CR-815330-02-0  by  Energy  &  Environmental  Engineering,  Inc.,
Somerville  Massachusetts  under  the  sponsorship  of  the  USEPA.
Ronald  Lewis  of  the  Risk  Reduction  Engineering  Laboratory,
Cincinnati,  Ohio was  the  project  officer  responsible  for  the
preparation of this  document and is deserving of  special thanks for
his helpful comments and advice throughout the project.

Participating in the development of this report for E3I, were Dr.
Michael  Mohr,  and   Dr.  William  Jackson.    Special  thanks  and
recognition are  deserving  of  Dr.  James Porter for his innovative
thoughts, Gopi Vungarala, Dave Tremblay.  Ann Jeffries, Don Streete
and our Laboratory staff for their endless efforts.
                               Vlll

-------
I    EXECUTIVE SUMMARY


In the two-year period from October  1988 to September 1990, Energy
and  Environmental   Engineering,  Inc.   conducted  a  laboratory
investigation  of  a  new  process  for destroying toxic  organic
compounds in dilute waste water solutions.  In this process, Laser
Induced  Photochemical Oxidative  Destruction  (LIPOD),  solutions
containing 10 to 200 ppm of organic  compounds were irradiated with
laser  generated  ultraviolet  radiation  in  the  presence  of  the
oxidant hydrogen peroxide.


The  effects  of  organic  concentration,  irradiation  exposure,
wavelength and oxidant concentration on the destruction efficiency
were   determined   for   a  series   of   representative   organic
contaminants, and a  preliminary design for a larger scale process
was completed.


Summary of Results

The  experiments  showed  that  the  LIPOD  process  is capable  of
destroying  from  90  to 99 percent of  the  organic contaminants in
dilute waste  water  solutions.   The  destruction process  occurs in
two  steps.    Some  of the  contaminant is  destroyed during  the
irradiation period of about one minute.  The destruction continues
after the solution is removed from the radiation field for a period
of hours until essentially complete destruction  is achieved.

Economic comparison of the LIPOD process with competitive processes
indicates that the LIPOD process can offer significant cost savings
over other ultraviolet treatment processes and carbon adsorption.

-------
II   INTRODUCTION

The Superfund Innovative Technology Evaluation (SITE) Program was
implemented  to  accelerate  the  development  and  application  of
innovative cleanup technologies at hazardous waste  sites across the
country.   The SITE  Program is  comprised  of the  following  five
component programs:


     . Demonstration Program

     . Emerging Technologies Program

     . Measurement and Monitoring Technologies Development Program

     . Innovative Technologies Program

     . Technology Trensfer Program


This  report  surmarizes  the  results  of  a  two-year  bench-scale
evaluation of the Laser Induced Photochemical  Oxidative Destruction
(LIPOD)  process,   sponsored  by  the  SITE  Emerging  Technologies
Program.

The LIPOD  process, is  based  on the photochemical  destruction  of
toxic  organic chemicals  in  dilute aqueous  solutions.    Energy
supplied by an excimer laser is absorbed by the organic molecules,
rendering them oxidizable by the oxidant hydrogen peroxide w^ich is
added to the solution.  The advantage of this process is that the
narrow band ultraviolet radiation is preferentially absorbed by the
organic molecules and hydrogen peroxide, with little being absorbed
by the surrounding water molecules.

Aromatic  and  aliphatic   organic   compounds,   and  particularly
chlorinated organics, are major contaminants  in ground waters at or
near hazardous waste  sites.   These species also  rank high on the
Environmental   Protection   Agency's   (EPA)   list   of   priority
pollutants,  even  at the parts  per billion  concentrations  often
found in the waste  waters.  Because of the very low concentrations,
detoxification of these waters is difficult and expensive.  Carbon
adsorption  and  UV  ozonation  are  currently in  use.    The  LIPOP
process shows promise of better performance  at a lower cost.

-------
Ill  CONCLUSIONS AND RECOMMENDATIONS
     CONCLUSIONS

     Laboratory scale testing of the LIPOD process has shown that
     the process  is capable of destroying 90  percent  or more of
     toxic  organic  compounds  in  dilute water  solutions.    The
     effects  on destruction efficiency of organic concentration,
     oxidant  concentration  and   irradiation  dosage  have  been
     determined for a series of representative organic compounds.
     On the basis of these results, the cost  of a commercial scale
     process  has  been  estimated  and found to be very competitive
     with  existing technologies which  are  now in use  for waste
     water detoxification.


     The chemistry  of the  LIPOD process  proceeds in two  steps, an
     initiation  step  followed  by  a  propagation  step.    In  the
     initiation step, some destruction  of the organic  occurs during
     the short duration  of the irradiation.  when  the solution is
     removed  from the radiation field, propagation of  the  oxidative
     destruction  continues over a  period of  hours  until  more than
     90 percent of  organic har been destroyed.


     RECOMMENDATIONS

     Results  to date suggest that  the  LIPOD  process  has  excellent
     potential for  effective removal of  organics from dilute waste
     waters   and  that  further  development  of  this  process  is
     warranted.    Treatability studies  in  the  laboratory using
     actual  waste  water samples  from  hazardous  waste  sites  are
     needed   to   establish  how  the  process  performs  on waste
     containing a variety of organic compounds and inorganic salts.
     Successful completion of these treatability studies would lay
     the  groundwork for  larger scale field testing of the process.

-------
IV   BACKGROUND INFORMATION

A.  Process Description

     Laser Induced Photochemical Oxidative Destruction  (LIPOD) is
     a process^developed at Energy and Environmental Engineering,
     Inc.  (E3I)   to  oxidize   low  levels  of  toxic organics  in
     contaminated waters  to non-toxic species.   The process has
     been  under  development  for  the past  seven years,  and its
     efficacy  relies on  the   use  of a  coherent electromagnetic
     radiation source in the UV portion of the spectrum to activate
     an exothermic process  in  the presence of an oxidant so as to
     initiate  a  chain oxidation reaction.   The UV  source  is an
     excimer laser which provides a high intensity, coherent energy
     source.   The  oxidant  is  hydrogen peroxide which is miscible
     with  water  in all proportions  and  thus provides sufficient
     oxygen  and  or  hydroxyl  radicals to completely  oxidize the
     toxic molecules.

     Unlike  other UV  irradiation  processes  in which  the  toxic
     molecules must be exposed continually to the UV  radiation with
     both hydrogen peroxide and ozone present as chemical oxidants,
     this process requires no ozone and  the contaminant  is exposed
     to the UV light source only for a very short time (< SOsec) to
     initiate  the  oxidative chain reaction.   Our  investigations
     have  shown   that   only   a   portion  of  the  fluid  to  be
     decontaminated  needs to be exposed to the UV radiation source
     in the presence of hydrogen peroxide.  This exposed fluid can
     be  contacted with  unexposed  fluid  and additional hydrogen
     peroxide  and  the entire  fluid  pool will  undergo  the chain
     oxidation reaction.

     A typical process flow scheme is shown  in Figure 1  , the  reed
     stream containing the toxic species and  the chemical oxidant,
     hydrogen peroxide, flow countercurrent to the laser beam in  a
     photochemical   reactor   where   the  toxic  compounds  are
     irradiated.   The overall reaction  chemistry  is depicted in
     Figure 2  .  When oxidizing halogenated organics,  the reaction
     byproducts are  carbon dioxide,  water,   and  the  corresponding
     halogen acid.

-------
WASTE
WATER
 CHEMICAL
  OXIDANT
 STORAGE
                FC
                                 INITIATION
PHOTOCHEMICAL
   REACTOR
                    SOLID
                    RESIDUE
            METERING
             PUMP
                                                    LASER
                            ^
         EFFLUENT
      STORAGE TANK AND
        PROPAGATION
         REACTOR
                      DECONTAMINATED
                         EFFLUENT
           Figure 1. Process Flow Scheme

-------
             UV Coherent Light Source
             Photolysis Reactor
             Oxygen Source
CaHbX + ( a + 0.25(b-1))O2    »  a CO2 +     H2O + HX
          0.5(b-1))H2O2    »  a CO2 + (2a+b-1) H2O + HX
     Figure 2. Overall Reaction Chemistry

-------
B.   Potential Application

1.   Introduction

     Since  the  industrial  revolution  in  the  United  States,
     industrial  waste  products  have  been  generated  in  ever
     increasing amounts and, in general, have been discarded in a
     very  haphazard  manner.    Little  thought was  given  to  the
     suitability of the industrial and municipal  landfills that
     were typically used  for disposal.  The Times  Beach and Love
     Canal cases have dramatically  illustrated  the  folly of past
     practice.

     In the 1970s,  increasing  public  concern with  the quality of
     the environment led  to federal legislation to  manage newly
     generated hazardous wastes as  well as  a separate program to
     deal with the  cleanup  of  existing uncontrolled  waste sites.
     This   legislation  is  commonly   known  as  the   Resource
     Conservation   and  Recovery  Act  (RCRA)  of  1976  and  the
     Comprehensive   Environmental   Response,   Compensation,   and
     Liability  Act  (CERCLA)  of   1980,  respectively.     CERCLA
     established the  Superfund program to provide a mechanism for
     expeditious  cleanup  of  the  worst  of   these  sites  and  has
     provided  the  focal  point  for marketing  a  wide   range  of
     services involved with the cleanup effort.

     Ground water contamination at  hazardous waste  sites results
     from leaching action from those landfills containing hazardous
     materials and  can be  composed of a variety of toxic organics.
     Among the most difficult of these  to deal with are a class of
     chemicals  known as  aromatic  organic  compounds.    They  are
     pervasive; they are not biodegradable; they are among the most
     toxic chemicals to be dealt with in the  Superfund Program; and
     they do not lend themselves to  simple destruction techniques.

     In addition to  the cleanup of Superfund  sites, a market exists
     for the neutralizing of toxic wastes in those industries that
     can  no longer dump  their  waste products  in  landfills  or
     discharge contaminants into water streams.  To a large extent,
     these  industries have  been  able  to   recycle the  hazardous
     chemical compounds, but small amounts of these materials must
     be  destroyed  prior  to  release   of   the  effluent  to  the
     environment.

2.   Superfund Sites

     The clean up of existing hazardous waste sites represents one
     of the most difficult and costly problems facing our society
     over the next  fifty years.  The clean  up activity associated
     with the  Superfund program  is estimated  by the  Office of
     Technology Assessment to  be  more  than  $100 billion with the
     cost of treating ground water contamination comprising more

                                7

-------
than 50 percent of the total.

Typically, the ground water at these  sites will contain trace
amounts of  organic contaminants that have  leached  from old
landfills.  The ground water clean  up program will  normally
consist of the following elements:

*    Taking   measures  to   prevent   further   leaching   of
     contaminants  into the aquifer.

*    An Assessment  of  the  plume  of  contamination  in  the
     aquifer   as   well   as   the   nature  and   amounts   of
     contamination.

*    Removal  and  treatment  of contaminated  groundwater with
     the  treated  water  either discarded or  returned  to  the
     aquifer.

Much of the early effort at cleanup has involved relocation,
removal, or on-site containment of hazardous materials and not
permanent destruction.  To  some  extent,  this only serves to
transfer  the  problem to another  location  to be  dealt with
another  day-    The   expressed desire   is   for  destructive
treatment  or  a   permanent  stabilization of the  hazardous
materials.  However,  little progress has been  made toward this
end, particularly  for the expensive, difficult and uncertain
task of contaminated waste and ground water cleanup.

The LIPOD process  is well suited to the ground water cleanup
problem.   It  is  capable  of destroying the low levels  of
organic contaminants normally  found at a  lower cost than
competing processes.   LIPOD represents a vast improvement in
the currently available technologies because it:

*    More   effectively   destroys  organic   compounds  than
     competing technologies.

*    Does  not  require   significant  post  treatment   as  do
     competing physical separation technologies.

*    Can be built in  such a manner as to be easily transported
     and operated  at  individual waste sites.


industrial Waste  Streams

The Resource Conservation and Recovery Act of 1976 (RCRA) , as
amended by the Hazardous  and Solid  Waste Amendments of  1984
(HSWA)  prohibits continued placement of RCRA  regulated wastes
in  or  on  the  land,  including placement  in  landfills,  land
treatment areas,  waste piles, and surface impoundments.   This
has resulted  in the  need for  new waste  management techniques

                           8

-------
     to  deal with  the  3-5 billion  gallons  of  waste  solvents
     generated annually.  Additionally each year about 70 billion
     pounds of chemicals considered hazardous under RCRA are used
     in the United States.  Of this, about 80 percent are organic
     compounds used in  pesticide  formation;  paint  and adhesives;
     cleaning;  and chemical  intermediates.     Of  the  hazardous
     materials to be treated the treatment process  chosen for use
     will normally be custom designed for each application and will
     depend on the following:

     *    The type of chemical involved

     *    The concentration of the waste stream

     *    The potential uses for recovered chemicals

     In most cases,  an aqueous stream containing trace amounts of
     contaminants  must  be treated  further prior to  unrestricted
     release to the environment.   Present practice,  in most cases,
     is to use  activated  charcoal  post  treatment  for these waste
     streams.  In some cases, this will remain the  best practice.
     However, for  most  of the  organic  compounds encountered,  the
     LIPOD process will be  more cost effective.

C.   Competitive and Complementary Technologies

     The  technologies  described  below  can also be  used  to treat
     contaminated waste waters.   They  may  be used  prior to LIPOD
     treatment to  reduce  high  concentrations of contaminants,  or
     they may  be competitive with  the  LIPOD process in treating
     very dilute solutions, or they may be  used after the LIPOD
     process to  capture organics that may not be easily destroyed
     by the LIPOD process (e.g. aliphatic saturated and conjugated
     organic compounds).

1.   Physical Treatment Processes.

     These processes are  based on physical methods of separation
     and generally do not  result in destruction of the contaminants
     in the waste feed stream.  The most common  of these processes
     are distillation,  stripping,  and adsorption.

     Distillation processes are applicable to high organic content
     wastes  but usually  generate  a  large  volume  residual that
     Contains appreciable organic  contamination.  Incineration is
     often the principal  means of  handling this type of residual.

     Air  stripping  is  generally  used on waste  streams containing
     inw  levels of  volatile contamination  with  steam stripping
               for streams  containing  somewhat higher levels of
               -ion   However, some level of residual  contamination
                additionaei  treatment can often be  expected  from

-------
     these technologies.
     ^S30? an* rSSin adsorPtion are  commonly used to remove trace
     amounts of contaminants to achieve low organic concentration
     levels.     The   adsorptive   materials  will   contain   the
     contaminants and must either be incinerated or put through a
     restorative  process leaving  a  slurry mixture  that  can  be
     incinerated.


2.   Chemical Treatment  Processes.

     Most of the chemical processes of interest for  the treatment
     of organic hazardous wastes  make  use  of  oxidation to render
     the wastes harmless.  The  methods  use either high temperature
     conditions or a catalyst to bring this about.

     The  Wet  Air  Oxidation  process  and  a  somewhat  similar
     Supercritical Water Oxidation process  cause  reaction of the
     organic contaminants with free oxygen in the waste stream by
     raising the temperature and pressure of the aqueous wastes to
     very  high  levels.    The  organic materials  are  generally
     converted  completely  to carbon  dioxide  and water  by these
     processes .

     UV/ozonolysis and other oxidation processes such as peroxide,
     potassium  permanganate, and  hydrogen  peroxide  treatments do
     not normally achieve total destruction  and must be considered
     as  a  pretreatment  step  for a  second  treatment technology,
     usually a biotreatment process.

3.   Biological Methods.

     Biological treatment processes used for the removal of organic
     solvents and other volatile organic compounds from industrial
     waste  streams can be  divided into two major categories: (l)
     aerobic processes,  and  (2)  anaerobic  processes.   In aerobic
     systems   microorganisms  use oxygen to  biologically oxidize
     compounds.   Anaerobic,  or oxygen-free,  biotreatment systems
     make use of a reducing metabolic process.  Typically a series
     of  reactions  involving  acetogens  (acid  generating)   and
     methananogenic bacteria cause organic compounds to be broken
     down into methane and simple organic acids.

     F*ch  of  these   processes  can  be  further subdivided  into
     suspended growth or attached growth systems. Suspended growth
     systems are characterized  by microbes moving freely within the
     w^te  stream or  being suspended by  mechanical  agitation.
     Attached  or  "fixed  film"  growth  systems  have   layers  of
     microbes attached to a suitable medium that comes into  surface
     contact with the  waste stream.


                                10

-------
      ™™      t5eatment   systems  are  generally   open  surface
     impoundments which require large land areas and considerable
     capital investments.   Aerated processes have the potential to
     produce significant air (and odiferous) emmisions.   Being open
     to  the environment,  the  treatment  plants  are subject  to
     weathering and their design features and biological kinetics
     are stressed by precipitation and temperature extremes.

4.   Incineration.

     Incineration  is  the  principal  disposal  alternative   for
     nonrecoverable,    flammable    solvent    hazardous    wastes.
     Incineration possesses several advantages as a hazardous waste
     disposal  technology,  including the following:

          Thermal destruction by incineration provides the ultimate
          disposal of hazardous wastes, minimizing future liability
          from land disposal:

          Toxic components of hazardous wastes  can be converted to
          harmless or less harmful compounds:

          The volume of  waste material may be reduced significantly
          by incineration: and

     -    Resource recovery (i.e., heat value recovery) is possible
          through combustion.

     While  incineration as a hazardous waste management technique
     possesses many potential advantages,  there are also two major
     potential  drawbacks:    environmental  impacts  and  costs.
     Incineration has the potential to affect both air and surface
     waters via stack emissions and fugitive emissions of volatile
     compounds,  and  the   production  of  solid wastes   (ash  and
     scrubber  liquors and scrubber sludge).

     Incineration facilities permitted to operate by  EPA under the
     provisions  of  RCRA  are  required  to   meet  environmental
     standards in the following areas:

          They must meet destruction and removal efficiency (ORE)
          standards.

          They must meet standards for the release of acid gasses
          from the stack,  including HC1.

          They must meet standards for the emission of particulates
          from the stack.

          They must meet  standards for limitation of emission of
          toxic air pollutants (e.g.,  toxic metals)  from the stack.


                                 11

-------
     Costs  of incineration are higher  than  most hazardous  waste
     management  alternatives.   Incineration  costs more  because  of
     the  large  energy  input requirements and  the  high  cost  of
     environmental  controls.    These  costs  vary widely depending
     upon waste  characteristics,  incinerator design, and various
     operational considerations.

Y    EXPERIMENTAL RESULTS

A.   Experimental Procedures

     Laser  destruction experiments were carried out  on a series  of
     hydrocarbons in dilute solutions, using air, dissolved oxygen,
     sodium nitrate,  and hydrogen peroxide as oxidants.

     The performance  of  these processes was measured in terms  of
     its  ability  to  destroy  toxics,  relative  to  the  maximum
     achievable  toxic destruction capability.   This  capability  is
     measured as the  difference between relative destruction with
     the light on and with  the  light  off.
     The relative destruction achieved  is defined as:
        E  =
                   — c
                     ^-out*
     where   C-  =  Inlet Feed Toxic Concentration to reactor

             C  .= Outlei: Feed Toxic Concentration, with Irradiation
             -out*
             C  =  Outlet Feed Toxic Concentration, no Irradiation
     which  is°the  relative destruction of the toxic with the light
     on  less the  destruction  obtained in  the  absence of  light.
     This  latter  term  accounts for  evaporation,  absorption  and
     other  processes  which  can  occur  in  the absence  of light.

     The maximum achievable value of E, (E^J , is obtained when  C
out
     =  0.
     The  process  performance  is then  measured  in  terms of  the
     destruction efficiency, defined as      .
      in  terms  of concentrations,  the expression reduces to:
     Percent  destruction  achieved = 100X  ---  =  100 X
                                                        c   - c
                                                        ^-out   '"o
                                          F               C
                                          '-'ma*               out
                                12

-------
   usedfo^r^3^6 measure °f Process performance and
   used  for  all  the data presented herein.
    H^         reP°rted< the percent of destruction achieved
was determined  as a  function of:

      . Toxic  Compound speciation

      . Oxidant  speciation

      . Aqueous  concentration of toxic

      . Concentration of oxidant

      . Irradiation Dosage

      . Irradiation wavelength, and

      . Time

To  assist in the  understanding  of the  results,  absorbance
coefficients  were  measured for  each  of  the  hydrocarbons
studied,  and  for a number of common  ionic species which might
be present in contaminated waste water.

A Lambda Physik excimer  laser was used to produce the coherent
light  source.   The  laser  was  calibrated  and  optimized  to
produce  energy  at  specific  wavelengths.     The  laser  was
calibrated daily before each experimental run, monitoring the
input  energy  to the reactor and the  output  energy  from the
reactor.

Analysis  of the toxic solutions before and after irradiation
was performed on a Hewlett Packard 1090 HPLC.  The  HPLC was
calibrated daily before each run and compared  to a five point
calibration   curve  generated  for  each  organic  compound.
Preparation of  standards and HPLC analysis were performed in
accordance with the methods approved by the EPA in the final
QA/QC plan accepted by the EPA for chemical analysis of water
and waste water.   Water blanks and 50  ppm  solutions  of the
toxic  compounds as standards were  all  analyzed before each
experimental  batch of irradiated samples, thus, ensuring some
degree  of  accuracy and  precision  in  the   observed  toxic
concentration changes.

Toxic  concentration  changes  in  the  water   solutions,  by-
nroducts  and column effluents were determined and monitored
bv observing  any changes on the five point calibration curves
apnerated  for  each  of  the toxic  species.    Complementary
?nalvses  were carried  out in  our GC/MS  laboratories  on the
nCre  and  irradiated  samples  to   identify   any  irradiated
products,  while  observing  the changes  in  initial  toxic

                           13

-------
concentrations .
Tnn HP*LC System used included a reversed phase RP18 Lichospher
iuu,  5  micron  column  with  100 by  2.1  mm dimensions  and a
variable  wavelength  Diode  Array  UV  Detector.    Irradiated
samples were collected in duplicate  at five time intervals of
u, 10, 30 50, &  80 minutes.   Upon collection the  samples were
analyzed on the HPLC and then stored in amber colored vials.
The samples in the vials were monitored over time to determine
the continued destruction.

50 ppm solutions  of the toxic compounds were made up in a 17
liter bottle.   The solutions were  fed to the  photochemical
reactor  by a  variable  speed  peristaltic pump,  set  at  30
ml/min.  When using hydrogen peroxide as the oxidanr the toxic
solutions  were  mixed  at  a mixing tee  with  the  peroxide
solution and then fed into a I  meter by 2 . 3 cm by 0 . 8 cm flow
reactor.   The solutions flowed countercurrent to  the  laser
beam  and  were  irradiated  in the  reactor.   The  irradiated
samples were then collected  from an exit port  in amber colored
vials with teflon lined caps for analysis.

Total organic carbon  (TOC)  analysis was  carried  out on the
duplicate  samples collected,  on a  Dohrman  carbon analyzer,
which measures any change in the total organic carbon content
of a  compound  as  the reaction proceeds over time.

PH measurements were continuously taken of the toxic solutions
before and after  irradiation.

Toxic Components

The   compounds   listed   in  Table   1    were   selected  as
representative  of toxic organics found  in waste  water.   UV
absorbance was measured for  each compound in the concentration
range of 10 to 200 ppm.  Absorbance  values are shown  in Table
1.  The absorbance measurements were carried out in the  190 to
250 nm  range  of the  spectra on a UV spectrophotometer .  The
absorbance at the standard irradiation wavelength  is  reported
in Table 1.

-------
          Table  1. Toxic Concentration and Absorbance


    Toxic Compound      Concentration,ppm        Absorbance

    Chlorobenzene            50                     1.49

    Dichloroethene           50                     1.30

    Dichloroethane           50                     0.33

    Benzidene               50                     1-44

    Hexanoic Acid            50                     0-41

    Bis-2-chloroethylether  50                     0.37

    Methyl  Ethyl Ketone     50                     O-38
     Chlorobenzene Cone.           Absorbance

     200                                1.580

     150                                1.548

     100                                1.526

      50                                1.492

      10                                1.260
Additionally the absorbance at the standard wavelength of 100 ppm
solutions  of  some common  ionic  species which may  be  present in
contaminated waste water were also obtained,  (Table 2).
                                15

-------
 ionic  species            Concentration^*           Absorbance

 Magnesium Chloride            100                      Q

 Magnesium Sulphate            100                      0>289

 Magnesium Nitrate             100                      1 546

 Sodium Chloride               100                      0_751

 Sodium Sulphate               100                      0.609

 Sodium Nitrate                100                      1.560

 Calcium Chloride              100                      0.727

 Calcium Sulphate              100                      0.362

 Calcium Nitrate               100                      1.564

 Water                                                  0.253

 Table   1  results  showed  that  Benzidine,  t-Dichloroethene  and
 Chlorobenzene exhibited high absorbances,  Hexanoic  Acid and Methyl
 Ethyl   Ketone  showed  modest  absorbance  values   while  Bis-2-
 Chloroethyl  Ether and t-Dichloroethane showed low absorbances.
 The  absorbances of the ionic  species  showed  very  low absorbance
 values in aqueous solutions  and except for solutions containing
 nitrates, the spectral values were not significantly different from
 that of pure water.   Therefore,  only nitrate containing solutions
 were  expected  to have  any adverse  or  impeding  effect  on  the
 process.   This  adverse  effect  may  be overcome by  shifting  the
 irradiation   wavelength.      Because   of   its   high  absorbance
 coefficient,  Chlorobenzene at 50 ppm concentration  was selected as
 the  representative compound  on which  most of  our  experimental
 studies were carried  out.

 50 ppm solutions of  Chlorobenzene were made up  and  a five point
 calibration curve established,  from which all concentration changes
 were measured.   Analysis  and close monitoring of the standard 50
 ppm solution with time showed that even after  a  3 month period the
 concentration had only changed by a factor of  <  10%.  This enabled
 us  to   monitor  concentration  changes  of  the  laser irradiation
 process during irradiation and for long periods  after, since there
 was not  a significant change in  the standard 50 ppm  solution.

The standard 50 ppm solutions were run on the HPLC before  and after
each set of the irradiated samples were analyzed each day.  It was
observed that there was no significant changes in the  standard with

                                16

-------
theeiaserSs^Tf  ^ W6re observed in the samples were due to
the laser  stimulated  reactions  initiated by the LIPOD process.

B.   Initial  Irradiation  and Oxygenation Experiments.

Initial  experiments  on the process  were  carried  out  employing
various  concentrations  of chlorobenzene  solution  in a batch mode
using  a  quartz cell.    The  emphasis of these  tests  was  to obtain
samples  of the irradiated toxics to determine  the  formation of any
by-products,  and  to establish run conditions and equipment design
rcr  the  continuous  flow  system.    As  these  experiments  were
exploratory  and  preliminary in  nature,  a  batch  cell system was
used,  thereby avoiding  complications that  could  arise  from  a
continuous flow system.

The  oxidation process  was initially thought  to  be  produced  by
dissolved  oxygen  in solution.   Calculations summarized in Table 3
show the maximum extent of reaction that  should be achievable ••'ith
various  toxic species as  is  limited by saturated oxygen  dissolved
in solution.   Table 4 and Figure 3 show  the destruction obtained
for   air   saturated   chlorobenzene   solutions    at   different
concentrations and  irradiation  dosages.   These results  indicated
that  at  very low  toxic  concentrations  <12.5 ppm,  competitive
absorption takes  place  between  the water and the toxic molecules.
Under  these  conditions  the ratio of  light  absorbed by  the water
molecules  to  the  light  absorbed  by the toxic molecules becomes an
important  limiting  factor in the photolysis  process.   At higher
toxic concentrations  >50  ppm the amount of oxygen  dissolved in the
solution is  too  low  to allow complete  oxidation of  the toxics.
Therefore best results were achieved at concentrations  between 12.5
and 50 ppm.

These  results led  us to  investigate  two schemes  for effectively
oxidizing  the  toxic solutions,  recycle  aeration   and  chemical
oxygenation.    The  baseline   case   against  which   all  of  the
oxygenation methods were  compared, is the system shown in Figure 4
where  the feed  solution  is  saturated   with  air  but no further
aeration occurs.   For all of the aeration  experiments, 50.0 ppm
chlorobenzene solutions were fed into the system and irradiated at
0 (method  Blank), 1,  3,  5,  and  10 photons per molecule.   Figure 5
shows  a  schematic  of the recycle  aeration  system,  using air and
pure oxygen as the  oxidant.


Aerated  Recycle systems

In cases where the oxidant  was insoluble  in water  (air,  oxygen)
aeration rates were achieved by aerating a recycle stream to  its
saturation value  and  then controlling the recycle rate.   At  0.208
atm and    70°F, the oxygen concentration in  an  oxygen  saturated
solution  is  2.9X10-7  gmmoles/  cc,  based  on  the  Henry's  law
constant.  In this  system the feed solution  flows  in the  reactor


                                 17

-------
                           Table 3
       Table 3. Calculation of Maximum Extents of Reaction as limited by

       dissolved oxygen




Basis:   Toxic + a02 — > bH20  +  cC02  +  dHCl  +  e  N02



         Oxygen saturation concentration  =     2.90E-07  gmol/cc

Toxic

Chlorobenzene
Benzidine
Dichloroethane
Dichloroethene
Hexanoic Acid
Bis-2-Chloroethyl Ether
Methyl Ethyl Ketone

Toxic

Chlorobenzene
Benzidine
Dichloroethane
Dichloroethene
Hexanoic Acid
Bis-2-Chloroethyl Ether
Methyl Ethyl Ketone



7
17
2
2
9
5
5



1
17
2
2
9
5
5

a

. 0
. 0
.5
. 0
. 0
.0
.5

a

.0
. 0
.5
. 0
.0
.0
.5

M

112 .
184 .
98.
96.
116.
142.
72.

M

112.
184.
98.
96.
116.
142.
72.



56
20
96
96
10
40
10



56
20
96
96
10
40
10
Toxic Cone.
(12.5 PPM)
gmol/cc
1. 11E-07
6 . 79E-08
1. 26E-07
1.29E-07
1. 08E-07
8.78E-08
1.73E-07
Toxic Cone.
(12.5 PPM)
gmol/cc
4 .44E-07
2.71E-07
5.05E-07
5. 16E-07
4 .31E-07
3 . 51E-07
6.93E-07
Maximum
Extent

of
Reaction*
0 .
0 .
0 .
1 .
0.
0 .
0.
Maximum
Extent
37
2 5
92
00
30
66
30

Of
Reaction*
0.
0.
0.
0.
0.
0 .
0.
09
06
23
23
07
17
03
a = Stoichiometric coefficient of oxygen  for  oxidation  reaction

M = Molecular weight of toxic compound

PPM = Parts  per million, mass:mass


*   Reaction extents for oxidation reactions  are  calculated

    as follows                                   ,,4.1
                                   [-Moles  Oxygen  Present]


Extent of  reaction =
                               Id

-------
                            Table 4
    Table 4.  Batch Pnotolysis of Chlorobenzene Solutions Saturated with Air


          Coutlet/Cinletat Vari°US  Inlet  Concentrations
Photons

molecule
Photons

molecule
 1
 3
 5
10
 1
 3
 5
10
                       3.125
 0.53
 0.39
 0. 37
 0.24

1 -
              inlet
                 12.5
                              out
 / c

0. 43
 0.2
0 .09
0.06
                                             50
inlet
    0. 49
    0. 29
    0. 15
    0. 09
                            (C    / C       )
                            (  out     inlet)
 0. 47
 0.61
 0.63
 0.76
0.57
 0.8
0.91
0. 94
    0. 51
    0.71
    0.85
    0. 91
                                                     100
0. 72
0.72
0. 58
0. 22
0. 28
0. 28
0.42
0.78

-------
|0
     ORE
                        468
                       Photons / Molecule
12
                        Inlet Concentration
               —3.125 PPM —12.5 PPM ^-50 PPM -*- 100 PPM

      Figure 3.   Impact of Irradiation Dose and Inlet
                  Concentration On Extent of Reaction
                  (Chlorobenzene saturated with air)

-------
  Outlet
 Collection
   Tank
                Sample
                Syringe
          Laser
            Mini
          Controller
                       Sample
                       Withdrawal
                       [Septum
                      Sample
                      Syringe

               Peristaltic Pump
                                   Inlet
                                 Collection
                                   Tank
                     Power
Photochemical
                     etectorn    Test Cel1
 Power
Detector
'Sample
Withdrawal
Septum
                                                  Power
                                                  Meter
                               Chart
                              Recorder
Figure 4.  Schematic of Test Facility for Non-Aerated
             Fluids

-------
reactor     Th   x^i? Solution'  takes place at the inlet end  of the
                  Ul
               x      °f  the  "action,  however,  occurs  at  the
        ?I,?/H     mixln<3  zone  between the toxic  and  the  aerated
                "^  the Ught  ^"sion P°rt of the reactor.  The
                reacted ""id leaves the reactor and is split into
nnn^nrr       af recycle  stream  and  a  product  stream.    The
concentration  of  air and/or  oxygen  in  the  recycle stream  is
restored to saturation levels by the aerator.   The recycle  rate is
controlled independently of the toxic solution  feed rate, and thus
controls the rate of oxygen to toxic  in the reaction zone.

Chemical Oxygenation

The  next  oxygenation technigue  examined  was  that   of  chemical
oxygenation employing hydrogen peroxide and sodium nitrate as the
oxygenating source,  (Figure 6).

First considering Sodium Nitrate,  absorbance experiments indicated
that aqueous  solutions of dissolved sodium nitrate, absorbs energy
in the  ultraviolet  region  of  the spectrum.   It was further known
that nitrates can act as electron acceptors,  and so could act as an
oxidant for the toxic solutions.   Since sodium nitrate is highly
soluble  in water,   the  problem of  dissolved   oxygen  solubility
limitation could be  overcome with the use of the sodium nitrate as
an oxygen  carrier.    In  these  experiments,  SOppm  solutions  of  a
mixture  of sodium  nitrate  and  chlorobenzene  were fed  into  the
reactor and irradiated.

The next experiments were conducted with hydrogen peroxide as the
chemical  oxidant.    In  these  experiments   (Figure   6)  hydrogen
peroxide is mixed at a mixing tee with the toxic solutions prior to
entering the reactor. The mixed solutions  of hydrogen peroxide and
toxic then flows down the reactor towards the laser.  The hydrogen
peroxide is very soluble  in aqueous solutions  and the oxidant level
can be  set at any desired value.   The general chemical  reaction
equation,  involving  hydrogen peroxide as  the  oxidant  is  shown in
Figure  2,

C6H5X +  14  H202  — hv ---- > 6 C02 +  16  H20 + HX


and was used to determine stoichiometric requirements.

For each experiment  run, the laser pulse frequency and toxic feed
flow rate  were set  to deliver  the  desired  irradiation dosage of
0135  and 10 photons / molecule.   The toxic  and oxidizing agent
concentrations were continuously monitored at the feed  and effluent
nnrtsbv  the  HPLC.   The  irradiated  and  non-irradiated  reactor
erfluent were  collected  and  analyzed within  thirty minutes after
the samples were collected from the  reactor.
                                22

-------
    Outlet
   Collection
    Tank
Peristaltic
  Pump
                                   Air Reservoir
ro
                  Sample
                  Syringe
                Sample
                Withdrawal1
                Septum
            Laser
              Mini
            Controller
^    .   Return
Recycle   Air
1
Aerato
\
/
c

r
S
                             n
                                       Blower
                           Sample
                           Syringe
  Inlet
Collection
  Tank
                                    Peristaltic
                                     Pump
                              Sample   L3
                              Withdrawal
                              J  Photochemical   |_
                           Power   Test Cell
                           Detector
                        Power septum
                     M Detector
                                                      Power
                                                      Meter
                                      Chart
                                     Recorder
       Figure 5.  Schematic of Aerated Recycle Apparatus

-------
                Recycle Oxidation

                       Reactor
    Toxicant Feed Solution
      in Equilibrium with
      0.208 atm Oxygen
                          A) Air
               Chemical Additive Oxidation
                        Reactor
Chemical Additive
Hydrogen Peroxide
  Laser Beam

     Effluent
Oxygenator
         B) Oxygen
 -TX. Laser Beam

 =i Effluent
 Figure 6.  Process Flow Oxygenation Schemes

-------
                              e
conditions had b«n achieved  in%h
                                                      -"ruction
                                              e"SUre Steady State
                                                             HPLC
                             "
sodium nitrate as a potential oxidant, no destruction occurred.  It
was deduced  that sodium nitrate is such a strong absorber of the
radiant energy at  the  wavelength used,  that very little radiation
was available to interact  with  the chlorobenzene
When considering air and oxygen in recycle aeration, destruction
was achieved, increasing with oxygen partial pressure, but only at
the  expense  of  high  irradiation  dosages.   These  results  were
discouraging, however, the results obtained with hydrogen peroxide
as  the  oxidant  led  to unique  discoveries discussed  in  the  next
section.
c.   Hydrogen  Peroxide  Results

The  toxic  destruction   using  hydrogen peroxide  as  the  oxidant
(Figure  7)  shows  destruction  equivalent  to using  oxygen  as  the
oxidant.  However,  these data are  the  results of samples analyzed
immediately after  being collected  from the  reactor.

Upon review and reanalysis of some of the  experimental samples, in
November  1989, the  following discovery was made, which was used to
set the  final  research  objectives  and  experimental parameters.

For  most  of   the  experiments  run  before  November  1989   on
chlorobenzene,  our  specific  target compound,  samples  were only
analyzed  right after they were  collected.   However, these samples
were stored in amber colored teflon lined capped vials,  and so were
available  to   be reanalyzed at a  later  date.   The  initial HPLC
analyses  gave results  that   were  far   from  encouraging,  but
reanalysis  and comparative review of the samples being stored in
the dark to the  initial  results  showed the  destruction  of  the
chlorobenzene  had continued during sample storage.   Similar results
were observed  for  all the samples  reanalyzed.

It was  discovered   and  confirmed  after several analyses that the
chlorobenzene  concentration and the Total Organic Carbon content of
the samples  sealed  in  the  amber  colored vials had diminished to
extremely low  levels in comparison to the  initial analyses   It was
subsequently substantiated  that reactions  leading  to  the toxicant
destruction were continuing for extended periods of time after the
initial  irradiation exposure period,  when  varying  stoichiometric
concentrations of hydrogen peroxide were present in the toxic  feed
solution ?   Further ^experimentation  and  analysis  showed that the
                                25

-------
                     INITIATION STAGE
 ORE  o.4
                   n  i  i  i i  i i m
                                                   100
                       Photons / Molecule
           -•- Air (2.0)             — Oxygen (6.0)
           -*-Sodium Nitrate (1.0)    ~*~ Hydrogen Peroxide (1.0)

           The Figure in Brackets Above Represents the Stoichiometric
           Oxygen Fraction Delivered.


Figure 7.    Destruction of Chlorobenzene by

              Various Oxidation Schemes

-------
which  con?inutn  Her lr/adiati°n source initiates a chain reaction
nronaaaM na ^     ^°nd  the  exP°su^  period  and   into  a  dark
?he toxicantseventually  leads to complete destruction of


A further test  was  carried  out, by irradiating a 1 liter solution
of  50  ppm chlorobenzene  containing  stoichiometric  quantities  of
hydrogen   peroxide.    The  gas  evolved  from  the  solution  was
CK  ^ f,     Calculation  show that  64.5  cc • s  of carbon  dioxide
should be produced  under  complete  oxidation conditions, presuming
that water and  hydrogen chloride stay in the aqueous phase.  sixty
eight  (68) cc's of  gas were measured, and this gas was soluble in
caustic solution indicating the presence of carbon dioxide.

Preliminary  studies  suggested  that the  reaction   rate  in  the
propagation stage was proportional  to the irradiation dosage during
exposure  to  the laser light  source.  Further,  it was found that
chlorobenzene and eventually the other  toxicants tested were also
reduced to non-toxic  gaseous species of carbon dioxide and water,
by observing and monitoring the total organic carbon  (TOC)  content
of the toxicants.  The TOC concentration was reduced significantly
as  the  reaction propagated  in  the dark,  correspondingly  we also
monitored and observed similar decreases in the pH as  the reaction
continued.  These results led to examination of the LIPOD process
as a laser stimulated initiation of the  destruction process,  which
leads to a propagating destructive  oxygenation reaction in the post
exposure  period.

After  running   50 ppm chlorobenzene  solutions  at three different
irradiation dosages  of 1,  3,  and 10  photons / molecule (Figure 8)
and at three different stoichiometric hydrogen peroxide ratios of
0.5,  1.0 &  1.5,   (Figure  9)  attention  was  focused  on  the
experimental   parameters    of   10   photons   /molecule  and   unit
stoichiometric  hydrogen peroxide.

Irradiation of  the  chlorobenzene solutions under these conditions
showed that after initial  laser irradiation, percentage destruction
was only 31%,  (Table 5, Figure 10).  However, continuous monitoring
of the reaction process with time in the propagating phase without
the  light  showed  that  greater  than   98%  destruction  of  the
chlorobenzene was achieved  after 115.5  hours,  (Figure 11).

Similar experiments were run on six other toxic compounds  (Table 5,
Fiaure 11)   The parameters were calculated for all other compounds
and  the  experimental  conditions  set  to  achieve   similar  run
parameters  as   that  of  the chlorobenzene case.   Monitoring and
analysis  of  these  tests  were  similarly  on an  initiation  and  a
propagation phase basis.

All the toxic compounds tested (except for t-dichloroethane)  showed
initial destructions  between 18  and  30  %,  while  testing over time
showed thaVthe destructions achieved had increased  significantly

                                27

-------
00
        ORE
                                     50 PPM Feed
               Concentration of Hydrogen Peroxide = 3.1 x 10"6 g-mole/cc
                 	i	i	\	i	i	i	
                    20
40     60    80    100
 Reaction Time (Hours)

  Photons / Molecule
120
140
       Figure 8.   Impact of Irradiation Dose on Exient
                    of Reaction

-------
ORE
1.0

0.8

0.6

0.4

0.2

0.0
                                                   * D
                  50 PPM FEED IRRADIATED AT 10 PHOTONS/MOLECULE
           CONCENTRATION OF HYDROGEN PEROXIDE = 3.1 x 10-6 gmole/cc
                                         6.2 x 10"6 gmole/cc
                                         9.3 x 10~6 gmole/cc
        0       20      40      60      80     100     120
                     Reaction Time (Hours)
                      H2O2 TO CLBZ RATIO
           + 0.5 STOICHIOMETRIC     * 1.0 STOICHIOMETRIC
           a 1.5 STOICHIOMETRIC

   Figure 9.   Impact of Hydrogen Peroxide
                 Concentration on Reaction Rate
  (HYDROGEN PEROXIDE ADDED AT 0.5,1.0 AND 1.5 TIMES STOICHIOMETHSC RATE)

-------
       Table  5.   Destruction of Various Toxic  Organic  Compounds  by  Laser
Compound       Irradiation  Dose
                (photons/molecule]
Benzene
Chlorobenzene
Chlorophenol
Dichloroethene
Benzidine
Phenol
10
10
10
10
10
10
            Initiation
             Destruction
              (percent)
29
31
34
18
48
35
         Propagation
          Time (Hr)
 96.0
113.5
 72.0
624.0
288.0
 72.0
Final  Destruction
  Achieved after
     Propagation
      (percent)

         91
         98
        >99
         88
         88
        >99
     The  system was  found  to  be dependenton an  initiation  and  a prpoagation
phase.   Limited destruction was  achieved  during  the photochemical  initiation
phase for all compounds irradiated.  Greater destruction  can  be achieved during
this phase only  at  the  expense  of applying  gieater  irradiation dosage.
     Analysis  and  observation  of the propagation  process  showed significant
changes in the final destruction achieved after a number of days depending on the
concentration  of the toxic organic compound present, the concentration of the
hydrogen  peroxide,  and the  irradiation  dose  applied  during  the  initiation
phase.
                                          30

-------
ORE
1.0

0.8

0.6

0.4

0.2

0.0
            50 PPM FEED IRRADIATED AT 10 PHOTONS/MOLECULE
             20
               40     60     80    100
                 Reaction Time (MIN)
           * CHLOROBENZENE
           a DICHLOROETHENE
                            * CHLOROPHENOL
                            x BENZENE
120    140
    Figure 10.   Extent of Reaction During the
                  Initiation Stage
         (HYDROGEN PEROXIDE ADDED AT STOICHIOMETRIC RATE)

-------
    ORE
                  50 PPM FEED IRRADIATED AT 10 PHOTONS/MOLECULE
                              i      i      i      i
                 100
200    300   400    500
Reaction Time (HOURS)
600
700
       + CHLOROBENZENE   * CHLOROPHENOL
       x BENZENE         O BENZIDINE
                  n DICHLOROETHENE
                  A PHENOL
Figure 11.  Impact of Irradiation on the Reaction Rate of
            Several Organics During the Propagation Stage
             (HYDROGEN PEROXIDE ADDED AT STOICHIOMETRIC RATE)

-------
          water   and  a  halogenated  acid,  given  by  a  simplified
equation approximating to:                              ^j-mpuriea


CAX +  (2a  +  0.5(b-l))H202 —hv—> aC02 +  (2a +  b-l)H2O + HX


In  July 1990,  a series of experiments with chlorobenzene were
begun, to determine  the effect  of toxic species  concentration and
irradiation  dosage  on  the  destruction efficiency  of  the LIPOD
process.   Chlorobenzene at concentrations  of  10,   20,  &  50 ppm
(mg/L) and irradiation dosages of 1 and 10  photons /  molecule were
used  in these  experiments.   The data  of the  results  shown  in
(Figures 12 and  13)  shows that  as toxic concentration diminishes,
there is an increase in the destruction  in the initiation phase but
there is reduction  in the rate of destruction in the propagation
phase.

The  observations  can  be explained  as follows.    As  the toxic
concentration  is reduced, the laser beam  penetrates further into
the  fluid,  and  a greater  fraction  of the  toxic  molecules are
exposed to the laser beam.  However, in the dark propagating  phase,
the reaction  becomes diffusion controlled with  the  reaction rate
being proportional  to  the  remaining  toxic and  hydrogen peroxide
concentrations.

This  conceptual  picture is supported  by  the data  presented  in
(Table  5,   Figure 11),   where  the  percent  destruction achieved
obtained in the  initiation and  propagation phases of the reaction
for all the compounds studied are presented.  The data  show that
the components which  exhibit high absorption coefficients achieve
the  greatest  amount  of  destruction  in  the  initiation   phase.
Correspondingly    those   compounds   with   compact    molecular
configurations and correspondingly high diffusivities tend  to show
faster reaction  rates in the propagation phase.

Impact of Irradiation Frequency

In order to reduce  the  possible reaction  interferences  caused  by
nitrates  in   solution,  50  ppm  chlorobenzene solutions were
irradiated  at a higher wavelength.    In  the  higher  wavelength
region,  the nitrate anions in solution show negligible  absorption.
Figure  14 represents  the  data  obtained in this  experiment    The
reaction shows  a similar  profile as,  was  obtained  at  the  lower,
i->=uv->_j.i_ni .JIIWTT^.             ..	j_j+.j_,4_^^_ -.r,^> nr-ni-iartal-inn
reaction snows a aa.iuj.j-aj.  ^^^^.^--—  —-
more energetic wavelength, with the same  initiation and propagation
Phase reaction characteristics, but at  an  overall  slower rate in
achieving  the  same  percent  destruction achieved.   This  slower
reaction9rate in ^propagation  phase  can be  attributed  to the
                                 33

-------
ORE
200      400      600      800

   Reaction Time (HOURS)
                 Chlorobenzene Concentration
                         Q20ppm   <>50ppm
                                                 1000
     Figure 12.  Impact of Feed Concentration

                  on Reaction Rate

         (HYDROGEN PEROXIDE ADDED AT STOICHIOMETRIC RATE)
             (SOLUTION IRRADIATED AT 1 PHOTON/MOLECULE)

-------
ORE
                200      400      600      800

                    Reaction Time (Hours)


                    Chlorobenzene Concentration
                 MOppm     a20ppm    <>50ppm
1000
      Figure 13.  Impact of Feed Concentration

                    on Reaction Rate

           (HYDROGEN PEROXIDE ADDED AT STOICHIOMETRIC RATE)
              (SOLUTION IRRADIATED AT 10 PHOTONS/MOLECULE)

-------
ORE
                 200         400        600

                   Reaction Time (Hours)
1000
 Figure 14.   The Impact of Irradiation Wavelength
               on the Destruction of Chlorobenzene
              (Hydrogen Peroxide Added at Stoichiometric Rate)
              (50 PPM CLBZ Irradiated at 10 Photons/Molecule)
                 (Irradiation Wavelength 28.5% > Normal)

-------
lower energetics of the  photons  at  the higher wavelengths.

Propagating Reaction Effectiveness

To test  the effectiveness of and  a possible  mechanism  for the
propagation reaction, an experiment was run in which  one fourth of
a 50  ppm chlorobenzene solution was irradiated and  then mixed with
the other  three fourths  of  non-irradiated solution,(Figure 15)
This  remixed  solution was monitored to determine the  extent  of
reaction  initiated  by  the  irradiated  molecules  and  hydrogen
peroxide,  to  see  if  the  fraction  of irradiated  molecules were
energetic enough to propagate  the oxygenation reaction.

Analysis of the results shown in Figure 15  shows that greater than
25% destruction was  achieved.    This  indicated that a  reaction
between irradiated and non-irradiated species does take place which
can eventually  lead to the destruction of  all  species.   However,
the reaction rates in  the  propagation phase is slower than in the
case  when the whole fluid pool  is irradiated even at one guarter of
the photon /molecule dosage.

Real  Waste Testing

In September 1990,  the LIPOD process was  tested  on  the leachate of
a landfill from a municipal solid waste burning facility.

A sample from  this waste facility was analyzed earlier in the year
for its organic content,  (Tables  6 and 7) .  The method used for the
real  waste  testing in September was based on  the total  organic
carbon  (TOC)  content  of  the  sample after filtration with 0.45
micron filters.   TOC  analysis  was done on the filtered  samples
shortly after arriving at E3I.   Based on the  TOC results  of 1200
ppm total  organic  carbon  in  the  sample,  the  concentration  of
stoichiometric  hydrogen  peroxide needed to totally  oxidize this
organic carbon  content of the  sample was calculated and employed
for the tests.

The results of  Figure 16  show that at the time of  writing this
report, after  six days,   the  destruction achieved  was 56  and  75
percent using five  and ten photons /molecule irradiation dosages
respectively.-  using stoichiometric  hydrogen peroxide.

D.   status

The process is  currently operating at the  bench scale level in  a
system with  1   GPM  capacity when  treating a toxic  waste  stream
containing 32PPM of total  organic carbon in solution.  The  impact
of   absorption   coefficient,    irradiation    dosages,    toxic
concentration,  hydrogen peroxide concentration and  the £«""« °J
common ionic species  in  solution on the destruction achieved and
reaction rate have been  determined for the six target compounds.
The ability of  the process to destroy  a given toxic compound is

                                37

-------
     1.0


     0.8


ORE 0-6


     0.4


     0.2


     0.0
D
     D
                      4       6     8     10

                      Reaction Time (Days)
                                          14
    Figure 15.   Impact of Irradiating a Portion
                   of the Fluid
                    (50 PPM CLBZ Irradiated at 4 Photons/molecule
                    1 Liter of Irradiated Solution Mixed with
                    3 Liters of Non-Irradiated Solution)

-------
Table 6. Semlvolatile GC/MS Anal
Compound
Phenol
Benzyl alcohol
2-Methylphenol
Isophorone
Benzoic acid
Dimethyl phthalate
Diethyl phthalate
Di-n-Butyl phthalate
Nitrobenzene
2-F1 uorobi phenyl
Terphenyl
2-Fluorophenol
2,4,6 Tribromophenol
Standards
1,4 Dichlorobenzene
Naphthalene
Acenaphthene
Chyrsene


24.29
7.29
1.49
1.33
162.80
1.06
5.00
1.18
125.46
96.08
102.47
164.37
210.48
Conentration (mg/L)
40.00
40.00
40.00
40.00
40.00

-------
Table 7. Semivol atile GC/MS Analysis of Real Waste (6/28)
Compound
Phenol
Benzyl alcohol
2-Methyl phenol
Isophorone
Benzoic acid
Dimethyl phthalate
Diethyl phthalate
Di-n-Butyl phthalat
Nitrobenzene
2-F1 uorobiphenyl
Terphenyl
2-Fluorophenol
2,4,6 Tribromophenol

Standards
1,4 Dichlorobenzene
Naphthalene
Acenaphthene
Chyrsene
Perylene
Concentration (mg/L
24.60
8.17
1.11
1.41
83.00 1

6.72

3.46
3.90
3.92
5.91
10.37

Concentration (mg/L)
40.00
40.00
40.00
40.00
40.00

-------
ORE
        0
2345

Reaction Time (Days)

 Photon / Molecule
   A 5     D10
  Figure 16.  Destruction of MSW Leachate
                 (Hydrogen Peroxide at Stoichiometric Rate)
                  (1200 ppm Filtered with 0.45 ^m Filter)

-------
measured in terms of  the  net  destruction achieved.

Summarizing results using hydrogen peroxide  as  the oxidant,  the
impact of the hydrogen peroxide concentration  on  reaction kinetics
is shown in Figure  10.  The stoichiometric quantities of H,0, used
in typical  applications  are  small.    Propagation  phase reaction
rates increased with  increasing peroxide concentration but in all
cases over  the ranges  studied greater than  95% destruction  was
achieved.  Figure 9  shows  the  impact of irradiation dosage, showing
that the greater  the  irradiation  dose received in the initiation
phase of the reaction,  the more rapid  the destruction rate during
the propagation phase.  Again, complete destruction  is attained in
all cases,  but this  observation provides a design  tr^>de off between
power cost to  initiate  the reaction and effluent storage reaction
capital  cost  to  contain  the  reaction  while  it  proceeds  to
completion in  the absence of  light.

Figure 15 shows the  impact of  toxic concentration  on  reaction rate.
Higher destruction  is seen to occur during the initiation phase as
the toxic concentration diminishes.   This  is  as  a conseguence of
the fact that the laser beam is able to penetrate further into the
photochemical  reactor  at lower  concentrations  because of  less
absorption by  a  smaller  number of toxic molecules.   Thus  as  the
toxic flows through the  reactor it is  exposed to  the  beam for a
longer period of time and hence exits the reactor at higher levels
of destruction.   However, in the  propagation  phase, the reaction
rate is species dependent, with the kinetics  following the law of
mass  action.    So,  the  higher toxic concentrations  react  more
rapidly during the  propagation phase  of the reaction.

The  impact  of common  ionic  species normally  found  in  waste  and
ground water on the  destruction^achieved were also determined.  Six
ionic species  were  examined  Na , Ca  ,  Mg  ,  Cl ,  SO42.,  and N03., of
which only the nitrate showed any form of impedance  on the reaction
process at the 193nm wavelength employed.  Nitrate  ions were found
to absorb  the radiation  at  the  lower wavelength,  however, tests
done at  a  higher wavelength showed that we  could overcome this
deficiency  since the  nitrate  ions  did not  absorb at  this  new
wavelength.

VI.  Quality Assurance

A  Quality  Assurance  Project  plan  for  "The  Laser  Stimulated
Photochemical Oxidative Destruction of Toxic Organics in Water" was
submitted  by  E3I in  December, 1988  to Dr.  Ronald Lewis, USEPA
Project Officer.  A  review of the  QA project  plan was received  in
February  1989. E3I responded to the  review comments  in a  revised
OA nroie'ct plan,  which  was  sent  to  Dr.  Lewis  in  July, 1989.
Revision 1 of  the QA project plan was accepted  by the USEPA  and
adhered to throughout the project.  As research proceeded,  results
directed attention toward several  new  areas for investigation.   The
work plan  for the  project  was expanded  and  altered somewhat  to

                                42

-------
were
accommodate   additional   experimentation.     These   changes
discussed  in  detail  and  approved by  the  project  officer
A technical systems audit of the  laser project experimental process
was  conducted  on  August  29-30,  1990.   The  following  areas of
laboratory operation were reviewed  for conformance to the quality
assurance  project  plan and standard  good laboratory  practice:

     Standard Operating  Procedures
     Sample Collection
     Analytical Methods
     Preparation of  Standards
     Instrument Calibration
     Quality  Control Procedures
     Preventative  Maintenance
     Documentation
     Safety
     Waste Disposal
     Reporting

Laboratory and technical  systems  for  the project were  determined to
be in control.  Procedures and documentation were found in order.


VII  Evaluation of the LIPOD Process

Based  on the experimental results,  the  following  criteria  were
established for the  successful application of the technology:

     1.   The UV radiation must be at a wavelength where the energy
           is  not significantly'absorbed  by the water molecules.

     2 .   The UV  radiation must  be  absorbed  by   the  hydrogen
          peroxide and the toxic organic.

     3.   The energy of  the absorbed photons must exceed the bond
          energy of  the   absorbing molecule  so as to be  able to
          cause  excitation and  fragmentation   and  thereby  a
          reaction.

     4.   A source of hydroxyl radicals, such as hydrogen peroxide,
          must be present to initiate the oxidative chain reaction.
          When using dissolved oxygen in  water as the oxidant, the
          effective  chain reaction does not occur, and the toxic is
          oxidized only  at  the expense of using high  dosages  of UV
          radiation.

Aromatic and  unsaturated organics,  which normally appear high on
the priority  pollutant list, meet the  above criteria and are  thus
good candidates for  the  successful application of the technology.


Table  8  shows an  operating comparison  between  the  UV oxidation

                                43

-------
         Table  8.  Operating Comparison of  UV Oxidation  Processes
Process
Issue
I r r ad i a t i on
Intensity
(Photons/Molecule)
Input Power
(KUatt-Hr/MGal) *
Hydrogen Peroxide
Requirements
(Crams/Cram "TOC")
Ozone Requi rements
(Gram/Gram "TOC") **
Power Output
Power Input
Power Source
Lou Intensi ty UV
Radiation Processes
Low
.005
27.1
H
1950
.1
High
.OH
79.1
990
2865
.1
Lou Pressure UV Lamp
LI POO
Low
.05
13.4
2.4
0
.01
High
2
53.2
4.8
0
.01
Excimer Laser
High Intensi ty u,"
Radiation Processes
Low
386
371
2.4
0
.1
High
115
-------
processes.  The UV processes require an oxidant,  normally hydrogen
peroxide, and  an  energy source to overcome the  activation energy
barrier  associated  with  the  oxidation  reactions.    The  high
intensity UV process uses the UV light source to supply  the energy.
The low  intensity UV process  uses  a  combination of the UV light
source and ozone to supply the activation energy. A comparison of
the high and low  intensity UV  radiation  processes and  LIPOD shows
a  clear  advantage  of  the  LIPOD  process  due  to its  ability  to
initiate a  chain  oxidative reaction which continues to propagate
the oxidation  reaction  in the  absence of any light.   This feature
could possibly allow the LIPOD process the  potential of being used
as an insitu "chemical"  remediation process.  Because the output to
input power  efficiency  of the laser  is less than  that  for  a  UV
lamp, the lamp power requirements are equivalent to that for the
low intensity UV process.  However,  the laser process requires far
less  peroxide  and  no  ozone  to  accomplish  the same level  of
destruction.   Similarly,  the  high  intensity UV process requires
modest peroxide levels  and  no ozone.   However,  the  irradiation
intensity  and  hence the  power  requirements   are  substantially
greater  than  in  the  LIPOD  process.    This is  due  mainly  to  the
coherence of the laser beam,  which allows the beam to maintain its
high intensity as it moves  further away from  its source.   It  is
also beam coherence and intensity  that leads  to  the  ability of the
process  to  initiate  a chain  oxidation reaction.   Tables 9  and  10
show  cost  comparisons  and  projections of  LIPOD's  costs  as  a
function of capacity respectively.

Carbon adsorption which  is the most commonly utilized technology in
the final clean up of trace  contaminants in aqueous waste streams
and  LIPOD  processes have  several  components   in  common.    For
example,  a typical 10 gpm polishing  system  would  require that both
employ the following:

          *     Pumps and piping,

          *     Instrumentation and controls,

          *     Filtration equipment to  remove potentially
                interfering suspended  solids.

In comparison to carbon  adsorption, however, the LIPOD process will
require additional capital for the laser.   For the trace amounts of
aromatic compounds for which LIPOD is especially well  suited, the
additional  capital  cost will  be  offset by the  reduced operating
cost of  the  LIPOD process:  eg.   The  cost  will be  recovered in a
period of  several  months.    Also the  carbon  adsorption process
recmires continual supply of activated carbon or alternatively the
use of expensive regeneration equipment.  This process also requires
the disposal of spent carbon as a hazardous  waste.

Based on  previously acquired information, and the effectiveness of
the present technology,  it is estimated  that the LIPOD process will

                                45

-------
   Table 9.
Cost Comparison of LIPOD to other Toxic Organic  Compound Removal
and Destruction Processes
 Basic  Data

 Feed flow rate
 Inlet  chloroaromatic concentration
 Destruction  &  Removal Efficiency  (ORE)
 Annual Capacity Factor
 Carbon cost
 Carbon disposal cost
 Carbon Loading
 Hydrogen Peroxide Cost
 Electric Power costs
 UV lamp Replacement
 UV lamp life
 Capital Recovery factor
 Process              LIPOD
 Capital Cost        $78,000

 Electric Power
 efficiency              .01

 Annual Operating
 & Maintenance costs
 (excluding labor)
 Electric Power

 Peroxide

 Laser Gases

 Carbon Cost

 Lamp Replacement

 Other Chemicals

 Maintenance &
 Insurance  (2% of
 capital cost)

 Capital recovery

Total

Cost per 1000
Gallons treated
                                  .815 GPM
                                   50  ppm
                                  . 99
                                   70 percent
                                 $ 3.00/lb
                                 $ 1.50/lb
                                   10 mg/gram
                                 $ 1.10/lb
                                   7.65 cents/KWHr
                                 $ 65/lamp (65 watts lamp)
                                   1 year
                                  .177 (10 years @ 10%)
                   Low  Intensity
                   UV radiation

                    $55,200
                          .1
High Intensity
 UV radiation

   $170,000
                                             . 1
776
2,571
1,969
0
0
0
1,560
13.806
$20,682
$68.94
$ 63,538
7,892
0
0
924
0
1, 104
9.770
$83,228
$277.43
$ 39,147
2, 571
0
0
37 , 045
0
3,400
23 .856
$106,019
$353 .40
    Carbon
Adsorption

  $30,000
                                                                             175
                                                           46, c:
                                                            7 , 5 0 C
                                                               60C
                                                           $59 ,585
                                                           $198.61
                                         46

-------
      TABLE 10.  LIPOD COST AS A  FUNCTION OF  CAPACITY
Capacity (GPM)

Capital Cost

Annual Operating
Cost (Excluding Labor
and 70% operating  factor)

Electric Power

Peroxide

Laser Gases

Maintenance & Insurance

Capital recovery

Total                     $

Cost Per 1000
Gallons Treated
               81,600
                  952


                3, 154


                2,415


                1, 632


              14 ,443


              22,596



              $61.42
                     10


                   360,000
                     9,518


                    31,541


                    24, 151


                     7,200


                    63, 720


                $  136,130



                    $37.00
     100


   2,160,000
      95,183


    315,415


    241,509


     43 , 200


    382 , 320


$ 1,077,627



     $29.29
                    LIPOD COST AS  A FUNCTION OF CAPACITY
              c
              A
              P
              I
              T
              A
              L

              C
              0
              5
              T
S^OOQOOO \
 11090004
                   $19,000
                         0.1
                                    SOppm
             BASIC DATA
              TOXIC CONC.
          ORE : 0.99
        ANNUAL CAPACITY FACTOR - 70*
   HYDROGEN PEROXIDE COST : J 1,10/18
ELECTRIC POWER  COST -• 7.65 CENTS/KWHfl
  CAPITAL RECOVERY FACTOR > .177
                 1        10      100
                 CAPACITY (GPM)
                                                         1000
    o
    p
    £
    R
    A
    T
    I
    N
    G

    C
    0
    5
    T
                                                                 M
                                                                 G
                                                                 A
                                                                 L
                                      47

-------
offer substantial savings in cost over all competing processes in
the applications for which  it is designed,   with the per gallon
treatment cost estimated not to exceed $0.10-$0.20.

In  summary,   LIPOD's   favorable   attributes  include  complete
conversion of  toxic organics  to non-toxic  species,  competitive
costs,  and potential to provide in-situ "chemical" remediation to
subsurface contamination.  Unfavorable features of the process are
its inability to effectively oxidize non-absorbing species such as
aliphatic saturated and conjugated organic compounds,  and as of yet
a lack of thorough understanding of the effect of particulates on
the process performance.  Aliphatic  compounds  are  not usually very
toxic,  and particulates may be removed by filtration.
                                48

-------