United States
 Environmental Protection
 Agency	
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
 Research and Development
EPA/600/S2-89/011 Sept. 1989
 Project Summary
 Treatability Potential for  EPA
 Listed Hazardous  Wastes  in  Soil
 Raymond C. Loehr
  This  study developed comprehen-
sive screening data on the treatability
in soil of:  (a) specific  listed haz-
ardous organic chemicals, and  (b)
waste sludge from explosives pro-
duction (KO44)  and related  chem-
icals.  Laboratory  experiments were
conducted using  two soil types,  an
acidic soil (Mississippi soil) with less
than one  percent organic matter, and
a slightly basic  sandy loam soil
(Texas soil) containing 3.25% organic
matter. These experiments evaluated
the: (a) relative toxicity of the  chem-
icals and waste,  (b) degradation of
the chemicals and waste in the soils,
(c)  adsorption characteristics  of the
chemicals in the two soils, and  (d)
toxicity reduction that occurred dur-
ing degradation.
  The major conclusions were:
1.  The chemical  structure  of the
   compounds evaluated affected
   their relative toxicity. With chlo-
   rophenols, the relative toxicity
   was related to the position  of the
   chlorine group on the phenol ring.
   The order of relative toxicity was
   para >meta >ortho. The  same
   order appeared  to  occur for
   methylphenols  and  nitrophenols.
   The chemical  substituted on the
   phenol ring appeared to have  an
   effect on toxicity.  Nitro-substi-
   tuted phenols appeared to be less
   toxic than the methyl- or chloro-
   substituted phenols. Mixing of the
   chemicals with the  soils did not
   affect  the relative toxicity  of the
   chemicals in the two soils.
2.  Data characterizing  the chemical
   loss in the soil and in the water
   soluble fraction (WSF) extracted
   from  the  soil as  well as the
   toxicity  reduction  In the WSF
   could  be represented satisfac-
   torily by either first or zero order
   kinetics. In most cases, the data
   were represented by either kinetic
   parameter with  high correlation
   coefficients.
3. The rates  of chemical  loss were
   higher  in the Texas soil. Chloro-
   phenols with chlorine substituted
   in the  meta position had greater
   half-lives and lower loss rates.
   Chemicals with a nitro  group
   substituted in the phenol ring ap-
   peared to have a lower loss rate.
4. The  Freundlich equation de-
   scribed the adsorption of most of
   the chemicals with the two soils
   satisfactorily. The values  of  the
   Freundlich constant (Kf) for  the
   chemicals in the two soils were
   different For the acid  extracta-
   bles, the K, values generally were
   greater in the Mississippi soil. For
   the amines and alcohols,  the K,
   values  were greater in  the Texas
   soil.
5. The loss of the  applied chemical
   in the soil  and in the WSF as well
   as the reduction  of  the WSF
   toxicity were compared for nine of
   the chemicals. The chemical loss
   in the  WSF was about 1.5 times
   faster than the chemical loss in
   the soil. The WSF toxicity de-
   creased at about the same rate as
   the WSF chemical concentration.
   No enhanced mobilization  of  the
   applied chemical occurred  during
   degradation.
  This Project Summary was  devel-
oped by EPA's Robert S. Kerr Environ-
mental Research Laboratory, Ada, OK,
to announce key  findings of the
research project that is fully docu-
mented in  a separate  report of the
same title  (see Project  Report order-
ing information at back).

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Introduction
  This study  was conducted  to provide
comprehensive screening data on the
treatability in soil  of: (a) EPA  listed
hazardous organic chemicals, and  (b) a
specific hazardous waste and related
chemicals. The results provide data that
can be  used  when  permitting decisions
are made  related to: (a) management of
spills, (b)  remediation of  contaminated
soils,  and  (c)  the use of land as a waste
management alternative. The degradation
and partitioning  data  can  be used as
input  to predictive models that estimate
the movement of chemicals  in the un-
saturated zone of the soil.  The models in-
tegrate the processes that affect chem-
icals in soil (degradation and partitioning)
so that an assessment can be made of
the extent to  which  protection of human
health and the environment occurs. The
understanding that results  from the use of
such  models  allows the identification of
chemicals  and wastes  that require control
to reduce or eliminate  their hazard
potential prior to application to soil. Lab-
oratory  studies were  conducted  to de-
termine:  (a)  degradation kinetics, (b)
sorption, (c) toxicity of the  chemicals and
waste, and (d) the  reduction  in toxicity
that occurred during degradation.


Designated Chemicals and
Wastes
  The chemicals and  specific  waste that
were  part of this study   are  identified
hazardous wastes. These chemicals can
be expected to be components of  many
industrial  compounds  and wastes that
enter the soil from spills and inadequately
sealed impoundments (pits, ponds and
lagoons) and as part of wastes applied to
operating  land  treatment units.  The
chemicals  that were evaluated are  iden-
tified  in Table 1. The  specific hazardous
waste, and  chemicals related to that
waste, that were  evaluated are noted in
Table 2.
  Samples  of the  explosives  waste
sludge (K044) and  the chemicals  TNT,
RDX,  and  HMX  were obtained with the
help of the  U.S.  Army Toxic and Haz-
ardous Materials  Agency  (USATHAMA).
A sample  of wastewater treatment sludge
resulting  from  the  manufacture and
processing of explosives  was obtained
from the Holston Army Ammunition Plant
with the assistance  of USATHAMA. This
material was  stored at 4°C until required
for analysis and use.
Soils
  The intent of this study was to provide
comprehensive  screening data  on the
treatability of specific chemicals and a
hazardous waste in soil. The charac-
teristics of  the soil  will  affect  the
degradation, sorption, and treatment po-
tential and two soils with  different charac-
teristics were used. One  was an acid soil
with a low organic content and the  other
was a basic  soil with a higher  organic
content  and  cation  exchange capacity
(CEC). The  acid  soil, obtained from an
area near Wiggins, Mississippi, was sup-
plied by researchers at Mississippi  State
University  and was  referred to as Mis-
sissippi soil. The basic soil was obtained
from an area near Austin, Texas, that, to
the knowledge of the personnel of this
project,  had  not  been  exposed to  in-
dustrial  chemicals or  wastes.  This  soil
was referred to as Texas  soil.

Relative Toxicity and Chemical
Loading
  The  relative toxicity tests that  were
conducted were  not intended to  provide
information on  toxicity  from  a  human
health or safety or from an environmental
standpoint. Rather, these tests were used
as a relative toxicity screening method.
Such  tests also can be  used to  identify
the relative toxicity reduction that occurs
when  chemicals and waste are managed
by the land treatment process.
  Although no single bioassay procedure
can provide  a  comprehensive  toxicity
evaluation  of a chemical, a valid toxicity
screening  test can  provide  information
about the relative toxicity of a compound
and  can  help  predict  non-inhibitory
chemical application rates. The Microtox*
system  is  a relatively simple,  rapid and
inexpensive  test  and  was used  as the
toxicity screening method in this project
to determine: (a) the  relative toxicity of
the chemicals and wastes, (b) the non-
inhibitory  chemical  and   waste  loadings
used  in the  degradation  studies,  and (c)
the toxicity reduction that occurred in the
respective  studies.  The  use  of the
Microtox® procedure  to  screen  and
predict the treatability potential of waste
in soil has been evaluated and found to
be satisfactory.

Degradation Studies
  These experiments were conducted to
determine the removal  kinetics of the
designated chemicals and wastes in soil.
Several of the chemicals could  no
evaluated because of chemical reac
in the soils that made analytical detei
impossible. These were  Diphenylan
m-Phenylenediamine and Thiophenol
  Biodegradation  is  believed  to  be
most  important removal  mechanism
organic compounds in soil systems.
degradation of organics is accompli:
in  a  series  of  biochemical  reacti
through  which a  parent compouni
changed  or transformed  to  organic
inorganic end products. Complete de
dation is the  term used  to describe
process whereby constituents  are mi
alized to inorganic end products, inc
ing  carbon dioxide, water, and inorg
nitrogen,  phosphorus, and sulfur c
pounds. Aerobic soil bacteria possess
ability to  biochemically catalyze
oxidation of organic compounds. For
reason, and because the zone of in
poration at land treatment sites genei
is aerobic, the protocol used  in this st
allowed aerobic conditions and aerc
biodegradation reactions to occur.
  The primary goal  of  biodegrada
testing is to obtain an overall estimati
the  rate  at which  a  compound  will I
degrade  in a  soil environment. While
compounds appear in the environmen
pure  form, a  common approach
studying  removal rates of organic c<
pounds has been  to evaluate  indivic
compounds. Although this approach f
vides  an  understanding  of the  rerm
rates for  specific compounds, it is rec
nized  that during  actual land treatm
chemicals  normally are applied as n
lures. Interactions between compounds
a mixture within the soil matrix may p
mote  or  inhibit their removal from s
The noted chemicals (Tables  1  and
were  evaluated as individual compoui
using  standard laboratory microcos
and protocol.
  In this  study, no distinction  was mi
between  specific  loss mechanisms. I
moval rates can be  due to biodegrai
tion, chemical  degradation,  hydroly;
photolysis  and volatilization.  The che
icals that were evaluated did not have
high volatilization  potential and volatili
tion was  not considered an important
moval mechanism in these degradat
experiments.
  The rate of  degradation  was  expe
mentally  determined by measuring I
difference  between the  amount of co
pound initially added to  a soil  and tl
which was recovered after specified tii

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Table 1. Chemicals
Compound
Acid Extractables
Phenol
o-Cresol
p-Cresol
m-Cresol
2-Chlorophenol
3-Chlorophenol
4-Chlorophenol
2,3-Dichlorophenol
2, 4 -Dichlorophenol
2,5-Dichlorophenol
2, 6-Dichlorophenol
3,4-Dichlorophenol
2,4,5-Trichlorophenol
2,4, 6-Trichlorophenol
Pentachlorophenol
2, 4 -Dimethyl phenol
2-Methyt-4-Chlorophenol
3-Methyl-4-Chlorophenol
3-MeV>yl-6-Chlorophenol
p-Nitrophenol
2,4-Dinitrophenol
4, 6-Dinitro-o-Cresol
Thiophenol
Amines
Diphenylamine
m -Phenylenediamine
Toluenediamine
Brucine
Alcohols
Isobutyl alcohol
Allyl alcohol
Propargyl alcohol
1-Butanol
2, 3-Dichloropropanol
Methanol
Other
Carbon disutfide
2-Nitropropane
Thiourea
that were Evaluated in this Study
Formula

C6H60
C7HgO
C7H80
C7H80
CgH5CIO
CeH5CIO
CgH5CIO
CeH4CI20
CeH4C/20
C6H4C/20
CeH4CI20
CeH4CI20
C6H3CI30
CeHyClsO
CgHClsO
CgH100
C-fH^IO
C7H7CIO
C7H7C/0
CeHgNOj
CeH^Os
CTH^OS
CeHgS

C12H,,N
CeHeA/2
C7/VWH2>2
^23^26^204

C4H,00
CaHgO
C3H40
C4H,00
C3H6C/2
CH4O

CS2
0^7^02
CH4W2S
EPA Hazardous Waste
Number

U188
U052
U052
U052
U048
NOS
NOS
NOS
U081
NOS
U082
NOS
U230
U231
U242
U101
NOS
U039
NOS
U170
P048
P048
U014

X016
X017
U221
P018

U140
POOS
P102
U031
X006
U154

P022
U171
U219

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                Table 2.
The Hazardous Waste and Related Chemicals that were Evaluated
                       Specific Hazardous Waste
                         K044 -    Wastewater treatment sludge from the manufacturing and processing of explosives
                       Explosive and Munitions Manufacturing Chemicals



                                Compound               Formula
                                                  EPA Hazardous
                                                  Waste Number
2,4-Dinitrotoluene
2,6-Dinitrotoluene
TNT (2,4,6-Trinitrotoluene)
RDX +
HMX+ +
C7H6A/204
C7H6N204
C7H5N306
C3H6A/606
C^gNgOg
U105
U106
-
-
-
                           RDX = Hexahydrotrinitrotriazine
                          + HMX = Cyclotetramethylenetetramtramine
intervals. A plot of the disappearance of a
constituent originally  present  in  the
chemical/soil mixture versus treatment
time provided the following: (a) the type
of reaction (generally zero or first order),
(b) the reaction rate constants for the
zero or first order reactions, and (c) the
half-life (t1/2) time of each constituent of
concern. The soil used: (a)  had not had
previous exposure to industrial chemicals
or wastes, and  (b) did not receive any
pretreatment such as soil amendments or
specially  acclimated  biological  cultures
prior to these experiments. The  naturally
occurring soil microbial consortium  was
responsible for the  bioremediated re-
moval of the chemicals.
   Chemical mass  loadings  were  deter-
mined as  part of  the toxicity screening
evaluations and ensured that the loadings
at which the chemicals were applied did
not inhibit soil microbial activity. Soil pH
was not adjusted nor were supplementary
organic substrates used.

Adsorption Experiments
   The persistence of hazardous  organic
compounds in soils is related to reactions
that affect the transport and fate of such
chemicals.  One of  the most important
reactions is adsorption. Adsorption is the
process  by which  ions  or  molecules
present in one phase tend to concentrate
at a surface or interface. The tendency of
organic  molecules  to adsorb on soil is
              determined by the physical and chemical
              characteristics of the chemical compound
              and the soil to which it is added. The two
              driving forces  for adsorption are  the
              lyophobic  (solvent-disliking) character of
              a  solute relative to  a particular  solvent,
              and the affinity of the solute for the solid,
              such as electrical attraction.
                 Adsorption  is  the  major  retention
              mechanism for  most  organic  and  inor-
              ganic compounds in soils. As a result, the
              leaching potential of a chemical in soil is,
              in general, proportional to  the magnitude
              of the  adsorption (partitioning)  coefficient
              of that chemical in a soil. The adsorption
              potential of a chemical is governed  by
              the properties of both the soil and the
              chemical.  Important  properties  of the
              chemical that affect  adsorption  include:
              (a) chemical structure,  (b)  acidity of
              basicity  of the molecule (pKa or pKb), (c)
              water solubility,  (d) permanent charge, (e)
              polarity, and (f) molecule size.
                 At equilibrium, the solute remaining in
              solution  is in dynamic  equilibrium with
              that of the soil surface. At this point, there
              is a defined distribution of  solute between
              the liquid and solid phases. The preferred
              form  for depicting  this distribution  is to
              express the quantity qe (amount of solute
              sorbed per unit weight of solid  sorbent)
              as a  function of the  equilibrium  solution
              concentration (Ce) at a fixed temperature.
              An  expression  of  this type  is  an
              adsorption isotherm.
  An  adsorption equation that has be
used  widely for  solid-liquid systems
the Freundlich equation:

              Qe = Kf C,""
where qe is the equilibrium  distribut
coefficient (mg  of  chemical/gm  of  j
sorbent),  Ce is the equilibrium  chemi
concentration (mg/liter of solvent), and
and 1/n are  constants The constant,
is  related  to the capacity or affinity of I
adsorbent and the  exponential term,  1
is  an  indicator of the intensity, or how I
capacity of the adsorbent varies with 1
equilibrium  solute  concentration. T
Freundlich isotherm has had  success
describing sorption behavior of organ
and the adsorption  data generated in tl
study were evaluated by this equation.

Toxicity Reduction
   A major objective of this  study was
provide comprehensive  screening d<
on the treatability  of specific orgar
chemicals in soil. Hazardous constituer
that enter the soil are to be detoxified
immobilized. When a chemical is add
to  the  soil,  it  is transformed  into otr
products  through chemical  and biologic
reactions  with or without complete detc
ification  and immobilization.  Measuri
the loss of the parent compound does r
assure that  complete detoxification  a
immobilization  occurs. Intermediate d
radation  products, which  may  be

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mobile  and/or  toxic than  the parent
compound, may  be generated as  the
parent compound  degrades. Additional
information on the transformation and/or
detoxification  of a chemical is necessary
to establish that the loss of the parent
compound leads to the complete detoxifi-
cation  of the chemical  or waste.  Such
information can be obtained using  either
chemical or bioassay analyses.
  The reduction of toxicity that  occurred
in selected degradation studies was eval-
uated by determining the toxicity of the
water soluble fraction (WSF) of the chem-
ical/soil  mixture at  the  same sampling
intervals  used to  obtain the degradation
data. The chemical compounds that  can
be  extracted  with water  represent  the
potentially leachable  fraction of  the
chemical or any  intermediate chemical
detoxification  products. The  WSF of the
chemical poses  the greatest threat to
groundwater  contamination.   Hence,
evaluating  the loss of  the  potentially
leachable  fraction  of  a  chemical is
important.  The concentration of  the
parent chemical in the WSF also was de-
termined. This concentration  was  ex-
pressed in terms of quantity of  chemical
that was water extractable per kg of the
soil. To put the toxicity reduction data in
perspective, the WSF toxicity reductions,
 he WSF chemical  concentration reduc-
tions and the soil  chemical concentration
reductions were compared.


Conclusions
  Specific  conclusions  based  on  the
results of the project include:
 1.  The Microtox0 biological assay rep-
    resents an appropriate method with
    which to evaluate the EC50 toxicity
    of a chemical or waste.
 2.  Comparison of the  EC50 data indi-
    cated that: (a) the alcohols were less
    toxic than the acid extractable com-
    pounds,  and  (b)  within chemical
    categories, there were considerable
    differences in relative toxicity.
 3.  The chemical structure  of the com-
    pounds evaluated affected  the rela-
    tive  toxicity of  a compound. With
    chlorophenols,  the  relative  toxicity
    was related to the  substitution posi-
    tion  of the chlorine group on  the
    phenol ring.  The order  of  relative
    toxicity was para>meta>ortho. The
     EC50 data suggested that the  same
    order occurred  for  methylphenols
    and nitrophenols.
 4.  The chemical that  was  substituted
    on  the phenol ring appeared to have
    an  effect on toxicity.  Nitro-substi-
    tuted phenols,  even  when substi-
    tuted in the para position, appeared
    to less toxic than  the methyl-  or
    chloro-substituted phenols.
 5.  When the chemicals  were  mixed
    with two different soils, and  the EC50
    value of the water soluble fraction
    (WSF) of  the   soil  mixtures  was
    measured, the values also  indicated
    that chemicals  with the  chlorine in
    the  para  position  had the greater
    toxicity. Mixing of the chemicals with
    the  soils  did not affect the relative
    toxicity of the chemicals in the two
    soils.
 6.  In general, the acceptable non-
    inhibitory  chemical loading  rates for
    the  Mississippi  soil were lower than
    those for  the Texas soil.  There was
    no   consistent  pattern  for  the
    differences.
 7.  The chemical or waste loading pro-
    cedure (described in Table 9, Sec-
    tion  4 of  the full report)  resulted in
    chemical loadings that did not inhibit
    the non-acclimated organisms in the
    laboratory microcosms,  except  in
    one  case  (4,6-Dinitro-o-Cresol).  This
    procedure provided a good estimate
    of  initial,  acceptable  chemical
    loadings  that can be  used in  lab-
    oratory degradation studies.
 8.  Both zero and  first order kinetics
    provided adequate representation of
    the data. For most of the chemicals,
    the  data could be  fit to  either
    kinetics with high correlation coef-
    ficients.
 9.  The rates of  chemical  loss were
    higher in  the Texas soil than in the
    Mississippi  soil. There did  not  ap-
    pear to be any  pattern to the differ-
    ences in rates in the two soils.
10.  Chlorophenols with the chlorine  sub-
    stituted in the   meta position  had
    greater half-lives and therefore lower
    chemical  loss  rates. This was  par-
    ticularly evident  with the mono-, di-,
    and  trichlorophenols in the  Texas
    soil.
11.  Chemicals that  had a nitro group
    substituted  on the  phenol  ring  ap-
    peared to have a lower loss  rate.
12.  The Freundlich  equation described
    the  adsorption of the chemicals on
    the two soils satisfactorily, with  high
    correlative coefficients, except for a
    few chemicals.
13.  The  range  of  chemical concentra-
    tions evaluated  ranged from the low
    mg/l  concentrations to near or  at
    saturation  concentrations, and for
    most chemicals covered two to three
    orders of magnitude. For these con-
    centration  ranges,  a linear  ad-
    sorption relationship, i.e., n =  1, did
    not occur.
14. The values of the Freundlich  con-
    stant (Kf) for the chemicals in the
    two  soils were different.  For   the
    acid extractables, the Kf values gen-
    erally were greater in the Texas soil
    which  had the higher pH and the
    greater organic carbon  content. For
    the  amines  and  alcohols, the  K,
    values  were  greater  in  the  Mis-
    sissippi soil, which had the lower pH
    and the lower  organic  carbon
    content.
15. Two loading  rates, the Texas soil,
    and nine chemicals (phenol and eight
    chlorinated phenols) were used in
    this study.  Both first and zero order
    kinetics satisfactorily fit  the  water
    soluble fraction (WSF) chemical loss
    data and the toxicity reduction data.
16. The  higher  chemical loading  rates
    resulted  in higher  chemical concen-
    trations  in the WSF and higher  WSF
    toxicities  at  the beginning  of the
    experiments.
17. The  higher  chemical loading  rates
    generally resulted in slower chemical
    losses (higher half lives)  and slower
    toxicity  reduction.  However, at both
    loading  rates for each chemical, the
    chemicals were degraded and the
    toxicity was reduced. No differences
    due  to  the   loading  rates  were
    apparent in zero order kinetics.
18. The  loss  of  the chemicals  in the
    WSF was about 1.5 times faster than
    the loss of the chemical in the soil.
19. The  WSF toxicity for each chemical
    decreased as the soil chemical and
    the WSF chemical concentrations
    decreased.
20. The WSF toxicity decreased at about
    the same rate as the WSF chemical
    concentration  when the data for all
    nine  chemicals were compared.
21. No enhanced mobilization of the ap-
    plied chemicals occurred as the deg-
    radation and detoxification occurred.
22. No water soluble toxic products ap-
    peared to be formed as the chem-
    icals were degraded in the soil.
23. The  Freundlich  equation  described
    the sorption of 2,4- and  2,6-Dinitro-
    toluene in the two soils satisfactorily.
    It did not do  so for TNT, RDX, or
    HMX.

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24. No  loss of 2,4-Dinitrotoluene occur-
    red over a 47-day study even though
    the  loading rate  used  was de-
    termined to be acceptable using pro-
    cedures discussed  in  Section 4  of
    the full report. Degradation loss rates
    were obtained for 2,6-Dinitrotoluene
    and TNT.  First order kinetics were a
    better  representation for TNT than
    were zero  order kinetics.
25. The half life of TNT in the Mississippi
    soil was shorter, and the loss faster,
    than in the Texas soil.  No difference
    in the loss rates in  the two  soils for
    2,6-Dinitrotoluene was apparent.
26. The  sludge  resulting  from the
    manufacture and  processing  of  ex-
    plosives contained: (a) high concen-
    trations  of  nitrogen  and  COD,  (b)
    concentrations generally less than 10
    mg/l  for  heavy metals, and  (c) no
    TNT, RDX or HMX.
27. The  munitions  sludge had  a high
    toxicity as  measured  by  the
    Microtox® procedure. The constitu-
    ents  causing  the relative toxicity
    were in  the soluble  phase  of  the
    sludge.

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  Raymond C. Loehr is with the University of Texas at Austin, Austin, TX 78712.
  Scott G. Hullng is the EPA Project Officer (see below).
  The complete  report, entitled "Treatability Potential for  EPA Listed Hazardous
   Wastes in Soil," (Order No. PB 89-166 581/AS; Cost: $21.95, subject to change)
   will be available only from:
          National Technical Information Service
          5285 Port Royal Road
          Springfield, VA22161
          Telephone: 703-487-4650
  The EPA Project Officer can be contacted at:
          Robert S. Kerr Environmental Research Laboratory
          U.S. Environmental Protection Agency
          Ada, OK 74820
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
-., I
Official Business
Penalty for Private Use $300

EPA/600/S2-89/011
                                                       885
                                               8R(NCH
                                           IL
     CHICAGO

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