United States
                             Environmental Protection
                             Agency
                   Solid Waste And
                   Emergency Response
                   (OS-220)
                                                                                    Directive 9200.5-252FS
                                                                                    November 1989
&EPA              Innovative Technology
                             Slurry-Phase  Biodegradation
 TECHNOLOGY DESCRIPTION

    Slurry-Phase Biodegradation (SPB) is
 potentially effective in treating various or-
 ganic contaminants. It involves the com-
 mingling of excavated contaminated soil
 and sludge with bioactive microorganisms
mass concentration. The residence time in
the reactor varies with the soil or sludge ma-
trix, the physical and chemical nature of the
contaminants, contaminant concentrations,
and the efficiency of the bio-oxidation reac-
tions. Upon completion of the process, the
slurry is dewatered and the treated soil is re-
             Figure 1: Schematic Diagram of a Typical Slurry-Phase
                      Biodegradation Treatment Facility
                                       To Aimnplwra
                                                           To Atmoiplw*
   Noo: *dip«*d tram MoTce, (no. tor Boot Alton t HnHon Ire
in a mobile batch reactor or an in-ground re-
actor. A typical treatment facility is shown
in Figure 1.
    Prior  to treatment, large-grained con-
stituents such as  stones and rubble are
physically removed from the waste. The
remaining waste is mixed with water to
create the desired slurry composition (50
weight percent solids maximum). The slurry
water may be contaminated ground water,
surface water, or another water source that is
brought on-site. The slurry is then mechani-
cally agitated in a reactor chamber which
creates arid maintains the appropriate ambi-
ent environmental conditions (e.g., nutrient
supply, temperature range, oxygen content,
and pH level) needed for maximum bio-oxi-
dation of the target contaminants. Microor-
ganisms may be added initially to seed the
reactor and/or atHfd continuously during
treatment to maintain the appropriate bio-
                                                                         effectiveness of this treatment on general
                                                                         contaminant groups is provided in Table 1.
                                                                            Factors limiting treatment effect! veness
                                                                         include the inherent biodegradability of the
                                                                         target contaminant, dissolved oxygen con-
                                                                         tent, operating temperature, soil/sludge char-
                                                                         acteristics, and the presence of reaction-in-
                                                                         hibiting compounds such as heavy metals,
                                                                         chlorides, or even biodegradation by-prod-
                                                                         ucts. Site-specific characteristics and their
                                                                         potential impact on the SPB  process  are
                                                                         listed in Table 2.
                                                                            Variables governing the biodegradation
                                                                         process and resulting effectiveness can vary
                                                                         greatly between laboratory and actual field
                                                                         conditions. Therefore, in order to accurately
                                                                         model the effectiveness of SPB treatment, it
                                                                         is necessary to conduct bench- or pilot-scale
                                                                         tests at each site of interest.
                                                                                       Table 1
                                                                            Effectiveness of Biodegradation
                                                                           Treatment on General Contaminant
                                                                               Group* for Soil and Debris
                                      deposited on-site.
                                         Advantages of SPB include the follow-
                                      ing: biodegradable organic compounds may
                                      be transformed into non-toxic compounds
                                      or mineralized; elaborate or sophisticated
                                      equipment is not required; and batch opera-
                                      tion may allow more accurate mass-balance
                                      determinations.  The major disadvantages
                                      are that the treatment time can be relatively
                                      slow and SPB is ineffective against  inor-
                                      ganic wastes. Applications and limitations
                                      of the SPB technology are discussed below.

                                      STTE CHARACTERISTICS AFFECTING
                                      TREATMENT FEASIBILITY

                                         SPB has the potential to (treat a wide
                                      range of contaminants such as pesticides,
                                      fuels, creosote, pentachlorophenol (PCP),
                                      polychkvinatedbiphenyls(PCBs), and some
                                      halogeriatedvolatiieorganks. Theprojected
                                                                                Treatablllty
                                                                                 Groups

                                                                              HOogmMd votattn
                                         HatogmMd Mntvotota
                                         Non-htiogwoMd
                                         PC84
                                         DtodnMFurm
                                         Oiganccymta*
                                                           Effectiveness
                                                             Insufficient DJU

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                 Tabto2
Slta-Spacif te Characteristics and Impacts on
  Sturry-Phas* Blodegradalton Treatment
QianctMtetfet
Impacting Proecu
FwaiMHty
VariaMawact*
competitor)
Waur sofabilty



Tamparatur* outslda
15* -70*0 rang*
Nutrtanl oaf Idancy
pH outslda
4.8 • 8.5 ring*
Mcrobial popuftUJon
Waurdtochargas
tndalrtmfcttmt

Praaanea at «t»vn»d
• HMvymauli
• Highly cntorlnattd
organic*
• Soma pasttddaa,
ftaroicidM
• inorganic sans
SoiMiudga composlton
(la.. c*y. humus)

R*Mon*for
ItA^mftHmt
rOfVmW
•MkotA^A
•TrtfMcx

by variation In bbtoglctl aaMy
Conumkwntt win tow lobbMy art
hardarioblodagrada

proosaa

La/gar, mom dVarta mterobW
population peasant In mis rang*
Lack of adaquata nutrlants (or
Motoglcal aaMy
InhMlen el Biological actMty
InaufNcrant population racufts In low
Wodagradallon rala*
Potantw anvtoraMntaf andtor
rtaatt Impact*

pamcte tta tor propar starry
cofflpoatlon
Can b* highly toxic lo
Clay and hufflus aovo oonianvnanii
ffloraUgMy

Action* to
IfnJmto
IH1D9CT8

Norw;
or tongv •^>o
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