United States
Environmental Protection
Agency
Solid Waste
and Emergency Response
(5306W)
EPA530-F-97-042
October 1997
www.epa.gov
Innovative Uses of  Compost
Bioremediation  and
Pollution  Prevention
         ach year agricultural effluents, industrial residues, and industri-
         al accidents contaminate surface waters, soils, air, streams, and
         reservoirs. A new compost technology, known as compost biore-
mediation, is currently being used to restore contaminated soils, manage
stormwater, control odors, and degrade volatile organic compounds (VOCs).
   Compost bioremediation refers to the use of a biological system of
micro-organisms in a mature, cured compost to sequester or break down
contaminants in water or soil. Micro-organisms consume contaminants in
soils, ground and surface waters, and air. The contaminants are digested,
metabolized, and transformed into humus and inert byproducts, such as
carbon dioxide, water, and salts. Compost bioremediation has proven effec-
tive in degrading  or altering many types of contaminants, such as chlori-
nated and nonchlorinated hydrocarbons, wood-preserving chemicals,
solvents, heavy metals, pesticides, petroleum products, and explosives.
Compost used in  bioremediation is referred to as "tailored" or "designed"
compost in that it is specially made to treat specific contaminants at spe-
cific sites.
   The ultimate goal in any remediation project is to return the site to its
precontamination condition, which often includes revegetation to stabilize
the treated soil. In addition to reducing contaminant levels, compost
advances this goal by facilitating plant growth. In this role, compost pro-
vides  soil conditioning and also provides nutrients to a wide variety of
vegetation.
           ) Printed on paper that contains at least 20 percent postconsumer fiber.

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 Soil  Bioremediation

 Heavy Metal Contamination
           r. Rufus Chaney, a senior research
           agronomist at the U.S. Department of
           Agriculture, is an expert in the use of
           compost methods to remediate metal-
           contaminated sites.  In 1979, at a denud-
 ed site near the Burle Palmerton zinc smelter
 facility in Palmerton, Pennsylvania, Dr. Chaney
 began a remediation project to revitalize 4 square
 miles of barren soil that had been contaminated
 with heavy metals.

   Researchers planted Merlin Red Fescue, a metal-
 tolerant grass, in lime fertilizer  and compost made
 from a mixture of municipal wastewater treatment
 sludge and coal fly ash. The remediation effort was
 successful, and the area now supports a growth of
 Merlin Red Fescue and Kentucky Bluegrass.

   Chaney has also investigated the use of com-
 post to bioremediate soils contaminated by lead
 and other heavy metals at both urban and rural
 sites. In Bowie, Maryland, for example, he found  a
 high percentage of lead in soils adjacent to houses
 painted with lead-based paint. To determine the
 effectiveness of compost in reducing the bioavail-
 ablility of the lead in these soils, Chaney fed both
 the contaminated soils and contaminated soils
 mixed with compost to  laboratory rats. While both
 compost and soil bound the lead, thereby reducing
 its bioavailability,  the compost-treated soil was
more effective than untreated soil. In fact, the rats
 exhibited no toxic effects from the lead-contami-
nated soil mixed with compost, while rats fed the
untreated soil exhibited some toxic effects.
      Photo courtesy of U.S. Department of Agriculture. ARS, Beltsville, MD.

Soil near the Burle Palmerton zinc smelter facility was so contaminated
with heavy metals that residents of neaiby towns were unable to grow
grass lawns and instead used stones and pebbles as shown above.
   In another study, Dr. Lee Daniels and P.D.
 Schroeder of Virginia Polytechnic Institute,
 Blacksburg, Virginia, remediated a barren site con-
 taminated with sand tailings and slimes from a
 heavy mineral mining plant. The application of
 yard waste compost revitalized the soil for agricul-
 tural use. The compost was applied at the rates of
 20 tons per acre for corn production and 120 tons
 per acre for a peanut crop.
         Photos courtesy of Virginia Polytechnic Institute, Blacksburg, VA.

A heavy mineral mining plant site with sand tailings and slime was
remediated for corn and peanut production with the application of
yard waste compost.
Organic Contaminants
   Dr. Michael Cole, an expert in the degradation
of organic contaminants in soil, remediated soil
containing 3,000 parts-per-million (ppm) of
Dicamba herbicide to nondetectable levels in 50
days. Cole mixed wood chips and mature compost
into soil to make the combined substrate 10 per-
cent (by volume) compost and wood chips and 90
percent contaminated soil. According to Dr. Cole,
Dicamba does eventually degrade in nonamended
soil; however, that process takes years instead of
days. In addition to speeding up the bioremedia-
tion process, use of compost can also  save money.
Traditional remediation by landfilling and inciner-
ation can cost up  to five times more than bioreme-
diation by composting technology.

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   According to Dr. Cole, compost bioremediation,
more than any other soil cleanup technique,
results in an enriched soil end product and leaves
the earth in better condition than before it was
contaminated.

Petroleum Hydrocarbon Contamination
   Soil at the Seymour Johnson Air Force Base
near Goldsboro, North Carolina, is contaminated as
a result of frequent jet fuel spills and the excava-
tion of underground oil storage tanks (USTs).
Remediation of several sites on the base is an ongo-
ing project since materials are continually loaded
or removed from USTs,  and jets are continually
refueled. The base deals with a variety of petrole-
um contaminants, including gasoline, kerosene,
fuel oil, jet fuel, hydraulic fluid, and motor oil.

   In 1994, the base implemented a bioremediation
process using compost made from yard trimmings
and turkey manure. Prior remediation efforts at
Seymour involved hauling the contaminated soil to
a brick manufacturer where it was incinerated at
high temperatures. Compared to the costs of haul-
ing, incinerating, and purchasing clean soil, biore-
mediation with compost saved the base $133,000
in the first year of operation. Compost bioremedia-
tion also has resulted in faster cleanups, since pro-
jects are completed in weeks instead of months.

   The remediation process at Seymour includes
spreading  compost on a 50- by 200-foot unused
asphalt runway, applying the contaminated soil,
then another layer of compost. Workers top off the
pile with turkey manure. Fungi in the compost
produce a substance that breaks down petroleum
hydrocarbons, enabling bacteria in the compost to
metabolize them. Clean-up managers determine the
ratio of soil to compost  to manure, based on soil
type, contaminant level, and the characteristics of
the contaminants present. A typical ratio consists
of 75 percent contaminated  soil, 20 percent com-
post, and 5 percent turkey manure. A mechanical
compost turner mixes the layers to keep the piles
aerated. After mixing, a vinyl-coated nylon tarp
covers the piles to protect them from wind and
rain, and to maintain the proper moisture and
temperature for optimal microbial growth.
Stormwater Management
         tormwater runoff is excess water not
         absorbed by soil after heavy rains. It
         flows over surfaces such as roads,
         parking lots, building roofs, driveways,
         lawns, and gardens. On its journey to
larger bodies of water (streams, lakes, and
rivers), municipal and industrial stormwater can
carry a wide range of potentially harmful envi-
ronmental contaminants, such as metals, oil and
grease, pesticides, and fertilizers. These types of
contaminants pollute rural water, damage recre-
ational and commercial fisheries, and degrade
the beauty of affected waterways, among other
things.

   Stormwater runoff must be treated before it is
discharged into water to meet the U.S.
Environmental Protection Agency's National
Pollutant Discharge Elimination System regula-
tions. To comply, some municipalities and
industries are turning to solutions that involve
compost technology instead of more expensive
traditional treatment methods, such as vegetated
filter strips or grassy swales (phytoremediation)
and holding ponds. These traditional methods
require much larger tracts of land than methods
utilizing compost and are limited in their
removal of contaminants. In one industrial area,
for example, a traditional holding pond required
3.5 acres and cost $45,000, while a compost
stormwater system, designed to handle the same
amount of runoff, required only 0.5 acre,
required less maintenance, and cost $17,300.

Compost Stormwater Filters
   The compost stormwater filter (CSF), one type
of bioremediator, is a large cement box with
three baffles to allow water to flow inside (see
figure on page 4). The CSF is designed to remove
floating debris, surface scum, chemical contami-
nants, and sediment from stormwater by allow-
ing it to pass through layers of specially tailored
compost. The porous structure of the compost
filters the physical debris while it degrades the
chemical contaminants.  Scum baffles along the
side  of the unit trap large floating debris and
surface films.

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  Typical CSF Unit
                                                 Energy
                                                 Dissipator
        The CSF bioremediator removes contaminants from stormwater by allowing water to flow through layers of
        specially tailored compost.
   This innovative stormwater filtration and biore-
mediation system uses a relatively small volume of
specially tailored compost made from leaves. The
compost is formulated to remove over 90 percent of
all solids, 85 percent of oil and grease, and between
82 to 98 percent of heavy metals from stormwater
runoff. A CSF typically has low operating and
maintenance costs and has the ability to treat large
volumes of water—up to 8 cubic feet per second.
When the compost filter is no longer effective, it
can be removed, tested, recomposted to further
remove any contaminants, and used in other com-
post applications, such as daily landfill cover since
the metals are bound by the compost.

Disposal of VOCs and Odor Control
          ompost bioremediation technologies
          also have been developed to remove
          VOCs that cause disagreeable or harm-
          ful odors in air. The removal process
          involves passing the contaminated air
through a patented, tailored compost. The compost
functions as an organic medium containing micro-
organisms that digest the organic, odor-causing
compounds. Industrial facilities have made use of
this compost technology to remove VOCs at the 99
percent level.

   Billions of aerosol cans are manufactured and
used annually in the United States in households,
 businesses, and industry. Many of these cans carry
 residues of paints, lubricants, solvents, cleaners,
 and other products containing VOCs. Disposing of
 used aerosol cans represents a significant expendi-
 ture, both to the communities that collect them
 through household hazardous waste programs and
 to the businesses and industry that generate, han-
 dle, treat, or store these wastes.

   Activated carbon is one technology that tradi-
tionally has been employed to treat these  cans prior
to disposal.  Canisters of carbon are used to physi-
cally adsorb VOCs from the cans. Activated carbon,
however, does not destroy the VOCs, but merely
stores them. Thus, once the carbon canisters
become saturated, they, in turn, must be
    Biofiltration vs. Bioremediation
  Biofiltration implies physically separat-
  ing particles based on their sizes.
  Bioremediation, by contrast, implies a
  biochemical change as contaminants
  or pollutants are metabolized by micro-
  organisms and broken down into harm-
  less, stable constituents, such as
  carbon dioxide, water, and salts.

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disposed of. This adsorbtive compost technology is
more suitable for some types of VOC-containing
products than is activated carbon, which is a poor
adsorber of acetone.

   Vapor-phase biofilters using compost are gaining
increasing attention as an alternative technology for
treating aerosol cans. This growth is due, in part, to
the high cost of conventional treatment and disposal
methods, as well as to new regulations concerning
VOC emissions from hazardous waste storage tanks
and containers. Unlike conventional VOC control
technologies, such as  activated carbon, biofilters actu-
ally break down hazardous contaminants into harm-
less products. They also offer low capital, life-cycle,
and operating costs—and require minimal mainte-
nance and energy. The energy required to power a
100 cfm airflow unit,  according to the manufacturer,
is rated at 20 amps. At 8  cents per kilowatt hour, the
cost of the requisite electricity is estimated at $1.80
per day. Additionally, according to one manufacturer,
vapor-phase biofilters maintain a consistent VOC
removal efficiency of 99.6 percent, even when
exposed to heavy or uneven surges of toxics.

Control of Composting Odors
   Rockland County, New York, recently
announced construction of a composting facility
with America's first large, industrial-sized, odor-
control bioremediation  system. The enclosed
55,000-square-foot facility will be  fitted with a
compost filtration  system that can process 82,000
cubic feet of air per minute. The air will be treated
using ammonia  scrubbers, then forced into an
enclosure stacked  with  compost and other  organic
materials that function together as an air filtration
system. The system binds odorous compounds,
which the micro-organisms in the compost then
degrade. This system has allowed  the Rockland
County Authority  to obtain a contractual guarantee
of no detectable odor at or beyond the site proper-
ty line from the contractor awarded the design,
construction, and  operating contract.

Biofilters in Municipal Use
   By converting its disposal operation from strictly
landfilling to one that utilizes a vapor-phase biofil-
ter, the Metro Central Household Hazardous Waste
collection facility in Portland, Oregon, saved nearly
$47,000 in hazardous waste disposal costs over an
18-month period. The facility used vapor-phase
Vapor-Phase Biofiltration
    One application of biofiltration technology
 involves placing punctured cans, contami-
 nated rags, or other items in the lower
 chamber of the biofilter. Next, the entire unit
 is heated to vaporize the contaminants.
 A small amount of air is then injected into
 the system to draw the now gaseous conta-
 minants through two separate layers of a
 compost-rich biomatrix. The bulk of the con-
 taminants are absorbed by the biomatrix at
 the first level, where most of the microbial
 activity takes place. The upper level serves
 as a surge control layer (to treat heavy or
 uneven surges of VOCs). Micro-organisms
 living in the biomatrix metabolize the
 absorbed organics as food, converting the
 pollutants into carbon dioxide and water
 vapor.
  Compost -
  Tray
  Direction of
  Air Floi

  Compost -
  Tray
 In a vapor-phase biofilter, air draws volatilized contam-
 inants upward through two trays of tailored compost.
 Micro-organisms in the compost metabolize the contam-
 inants, converting them into carbon dioxide and water
 vapor.

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 Benefits and Disadvantages of Using Vapor-Phase Biofilters
 Benefits
 •  Low capital costs
 •  Low operating costs
 •  Limited energy and
    maintenance requirements
 •  High reliability
 •  Consistent pollutant
    removal
Consistent destruction
rates
No hazardous combustion-
related byproducts
Destroys VOCs, and thus
does not require secondary
disposal (unlike activated
carbon)
Disadvantages
•  Requires consistent
   loadings
•  Requires more square
   footage of space than con-
   ventional disposal methods
biofilters to remediate over 38,000 aerosol cans. As
a result, it lowered its disposal costs from $505 per
loose-packed drum to $265 per drum (from $2.35
per can to $1.30), since the cans were no longer haz-
ardous and did not need to be handled as such.

References

Cole, M.A., X. Liu, and L. Zhang. 1995. Effect of compost
addition on pesticide degradation in planted soils. In
Bioremediation of recalcitrant organics. Edited by R.E.
Hinchee, D.B. Anderson, and R.E. Hoeppel. Columbus:
Battelle Press.

Chaney, R.L., and J.A. Ryan. 1994. Risk based standards
for arsenic, lead, and cadmium on urban soils. Frankfort:
Dechema.

Chaney, R.L. et al. Phytoremediation potential of Thlaspi
caerulescens and bladder campion for zinc-and-cadmi-
um-contaminated soil. Journal of Environmental Quality.
23: 1151-1157.

Fordham, Wayne. 1995. Yard trimmings composting in
the Air Force. Biocyde. 36: 44.

Garland, G.A., T.A. Grist, and R.E. Green. 1995. The com-
post story: From soil enrichment to pollution remedia-
tion. Biocyde. 36: 53-56.
 United States
 Environmental Protection Agency
 (5306W)
 Washington, DC 20460

 Official Business
 Penalty for Private Use
 $300
               Schroeder, Philip D. 1997. Restoration of prime farm land
               disturbed by mineral sand mining in the upper coastal
               plains of Virginia. Master's Thesis, Virginia Tech.

               Stewart, W.C., and R.R. Thorn. 1997. Test results and eco-
               nomics of using an innovative, high-rate, vapor-phase
               biofilter in industrial applications. Portland. Typeset.

               Stewart, W.C. 1994. Compost stormwater filter engineer-
               ing system. Environmental Excellence Award and
               Innovator of the Year Award Presented by the Association
               of Washington State Business. Mimeographed.

               For  More  Information

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