United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-81-011 Apr. 1981
Project Summary
Impact of Resource
Conservation and Recovery
Act on FBC Residue Disposal
C. C. Sun, R. A. Newby, and D. L Keairns
The Resource Conservation and
Recovery Act of 1976 (RCR A) created
a new level of regulatory control of
solid waste disposal. The emphasis of
the Act is on identifying hazardous
wastes, regulating hazardous waste
from cradle to grave (RCRA Subtitle
C), and improving nonhazardous waste
disposal practices (Subtitle D). The
fluidized-bed combustion (FBC) process
for electric power generation produces
large quantities of residue (spent
sorbent and ash) which are subject to
RCRA control. The key provisions of
RCRA that have the greatest impact
on FBC residue disposal are Subtitles
C and D. This report provides an
assessment of RCRA and its current
regulations with respect to FBC resi-
due disposal and, of special importance,
the proposed Sec. 3001 regulations
for hazardous waste identification.
RCRA tests, in particular the Sec.
3001 extraction procedure (EP), were
performed on a variety of FBC residues
representing several process variations.
Results indicate that FBC residue is
nonhazardous. The impact of RCRA
regulations and criteria proposed prior
to promulgation on May 19,1980, on
FBC residue disposal is assessed.
This report on the impact of RCRA
contains the results of work defined
and completed as part of the spent
sorbent and ash disposal task of the
contract. Work on this specific task
was performed from January 1979 to
March 1980. Related documenta-
tion is found in the following reports:
"Disposal of Solid Residue from
Fluidized-Bed Combustion: Engi-
neering and Laboratory Studies,"
EPA-600/7-78-049 (NTIS PB 283-
082), issued in March 1978, which
presented the results of work per-
formed from January 1976 to Jan-
uary 1977
"Experimental/Engineering Sup-
port for EPA's FBC Program: Final
Report, Vol. Ill, Solid Residue
Studies, EPA-600/7-80-015c, is-
sued in January 1980. The report
documents work performed from
January 1977 to January 1979 and
subsequent extensions from review
of the draft through October 1979.''
This Project Summary was develop-
ed by EPA's Industrial Environmental
Research Laboratory, Research
Triangle Park. NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
Fluidized-bed combustion (FBC) is an
emerging technology that is being
developed to utilize coal in an environ-
mentally acceptable manner. FBC
processes, operated at atmospheric
(AFBC) or at elevated (PFBC) pressure,
employ limestone or dolomite to remove
sulfur during combustion, thus elimina-
ting the need for flue gas desulfurization
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(FGD). Unlike the scrubber sludges, dry
granular solids of 0 to 6 mm in diameter
result from the FBC process. There are
two major sources of solid residue from
an FBC system: spent bed overflow
material and entrained carry-over. The
former consists largely of partially sul-
fated limestone or dolomite sorbent
(calcium sulfate[CaSO.i], calcium oxide
[CaO], calcium carbonate [CaCOs],
magnesium oxide [MgO]); and the latter
consists of finer particles of partially
sulfated sorbent and coal ash and char
entrained from the bed and captured by
a paniculate control system. The carry-
over is typically collected in several
stages of the paniculate control system
commonly represented by cyclones,
baghouses, electrostatic precipitators,
granular-bed filters, etc.
Major concerns for FBC residue dis-
posal are the high pH, total dissolved
solids (TDS), calcium, and sulfate (SO*)
levels in the leachate; the thermal
activity; and the quantity of solid to be
disposed of. Heavy metal elements and
total organic carbon (TOC) in FBC leach-
ate are typically below the drinking
water standards (DWS) or the detectable
levels.
On the basis of our findings, we have
concluded that residue disposal will not
be an obstacle in the commercialization
of the FBC process, but further investi-
gation is required. For example, will FBC
residue be classified as hazardous or
nonhazardous waste under the Re-
source Conservation and Recovery Act
(RCRA), and how will RCRA regulations
affect FBC residue disposal?
Conclusions
The fluidized-bed combustion (FBC)
process for electric power generation
produces solid wastes that fall under
the jurisdiction of RCRA. The key pro-
visions of RCRA that could have the
greatest impact on FBC residue disposal
are Subtitle C on hazardous waste man-
agement, in particular the hazardous
waste identification criteria under Sec.
3001 and Subtitle D, which regulates
disposal of nonhazardous waste.
Impact of Hazardous Waste
Identification Criteria on the
Classification of FBC Residue
(Subtitle C)
RCRA Sec. 3001 of Subtitle C requires
EPA's Office of Solid Waste (OSW) to
promulgate criteria for identification of
hazardous waste, which OSW began to
develop in 1977. In March 1978, a
first draft was released which contained
tentative hazardous identification meth-
ods. A toxic extraction procedure (TEP)
was drafted to determine the toxicity of
a waste. Those wastes whose TEP
leachate had 10 times the National
Interim Primary Drinking Water Regu-
lations (10 x NIPDWR) would be con-
sidered hazardous. Public comments
were requested on the draft regulations.
We responded by testing typical FBC
residues and reference materials (raw
sorbent and conventional FGD residue).
Results of our TEP testing and recom-
mendations on the TEP procedure were
communicated to EPA in 1978.
On December 18,1978, EPA formally
proposed in the Federal Register RCRA
Sec. 3001 regulations which were
scheduled to be promulgated in April
1980, following completion of this
report. The TEP was significantly modi-
fied on the basis of the additional infor-
mation supplied by public comments
(including our recommendations) and
was renamed the "extraction procedure"
(EP) with 10 x NIPDWR of heavy metal
elements as the hazardous criteria.
According to proposed Sec. 3001, a
waste can be classified as hazardous
either by being on the hazardous lists
(proposed by EPA on December 18,
1978, and August 22, 1979) or by pos-
sessing any of the proposed hazardous
characteristics. The FBC residue is not
on the hazardous lists and, therefore, its
classification must be determined from
the proposed criteria for hazardous
characteristics—ignitability, corrosivity,
reactivity, and toxicity. Of the four char-
acteristics, toxicity, for which EPA has
proposed an extraction procedure (EP)
and hazardous criteria (10 x NIPDWR),
causes the most concern for FBC resi-
due. Because of the potentially large
volume of residue from various indus-
trial sources and the limited data on
their potential hazard, EPA has proposed
a list of "special wastes" under Sec.
3004; "utility waste" is among these
five special wastes. Should FBC waste
be deemed hazardous according to Sec.
3001, we expect it would be classified
as a utility waste under the special
waste category and would be regulated
with partial exemption from the cradle-
to-grave regulations under hazardous
waste management Sec. 3002 to 3005.
On the other hand, should FBC waste be
identified as nonhazardous, it would fall
under the jurisdiction of Subtitle D, and
its disposal would then be regulated as a *
sanitary landfill waste.
FBC residue is not ignitable, corrosive,
or reactive according to the proposed
criteria. To determine if it is toxic, 17
FBC residues representing several
process variations, [atmospheric (AFBC)
and pressurized (PFBC) fluidized-bed
boilers/PFBC adiabatic combustor,
bed/carry-over, with/without carbon
burnup cell (CBC), once-through/re-
generative operation, limestone/dolo-
mite sorbents] together with reference
materials (FGD residues, conventional
ash, and raw sorbent) were tested using
the former TEP and the proposed EP
tests. Results that showed the EP leach-
ates to have Ag, As, Ba, Cd, Cr, Hg, Pb,
and Se below 10 x NIPDWR indicated in
the FBC residue to be nontoxic and,
thus, nonhazardous. The only exception
among the EP leachates of 17 FBC resi-
dues was the leachate from an Exxon
PFBC run with sorbent regeneration
which had an average As concentration
of 0.94 ppm (compared to the criterion
of 0.5 ppm). AFBC and PFBC fines
(< 15 //m) from the third-stage cyclone
and bag filter and PFBC regenerator bed
material had Cr concentrations in their
EP leachates (0.15 to 0.4 ppm) much |
higher than the others (< 0.1 ppm) and
were close to the criterion for Cr, 0.5
ppm. Future investigations, therefore,
should emphasize samples from these
sources.
We assumed that the FBC residues
would not contain chlorinated organic
pesticides and herbicides and, thus, did
not perform EP analyses for Lindane,
Methoxychlor, Toxaphene, or 2.4-D and
2.4.5-TP Silvex, which were also pro-
posed in Sec. 3001.
Bioassays and testing for radioactivity
were not included in the proposed iden-
tification methods for hazardous char-
acteristics (ignitability, corrosivity,
reactivity, and toxicity) and thus were
not carried out in our investigation on
FBC residues. However, EPA is con-
sidering expanding the hazardous char-
acteristics to include radioactivity,
genetic activity, bioaccumulation, and
additional aspects of toxicity (Advanced
Notice for Proposed Rulemaking, Fed-
eral Register, December 18, 1978).
Oak Ridge National Laboratory (ORNL)
conducted bioassays on fossil fuel
residues under DOE and EPA contracts
and reported that FBC residue showed
negative results in mutagenicity, in
aquatic and phytotoxicity, and in metal
elements, agreeing with our conclusion
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that the FBC residue is nonhazardous.
ASTM D19.12 also carried out bioassay
tests; results are less conclusive due to
difficulties encountered in sample pre-
paration, test procedures, and interpre-
tation of test results.
Impact of Nonhazardous
Waste Disposal Regulations
on FBC Residue Disposal
(Subtitle D)
According to the current regulations
promulgated on September 13, 1979,
eight criteria, including site selection
and leachate monitoring, apply to the
nonhazardous solid waste sanitary
landfills, where FBC waste would most
likely be disposed of. The most important
issues that can affect the FBC residue
disposal, however, a re the standards for
ground and surface water. Compliance
with RCRA and the National Pollution
Discharge Elimination System (NPDES)
under the Clean Water Act (CWA) is
required of a sanitary landfill. Efforts by
EPA are under way to consolidate the
solid waste permit system. Since efflu-
ent guidelines for FBC units and FBC
residue disposal facilities are currently
unavailable, engineering judgment
must be applied for designing, operating,
and managing the disposal facility to
avoid potential adverse environmental
effects. Because FBC leachates meet
the primary DWS which consists of
eight heavy metals, fluoride (F), and N03,
FBC residue disposal is expected to meet
the current standards for sanitary land-
fill— groundwater at the "disposal
facility boundary" must satisfy the
primary drinking water standards
(NIPDWR). Should the secondary DWS
(NSDWR) be included as they are currently
proposed (Federal Register, September
13, 1979), however, FBC leachate pH
would be a major concern as the pH of a
typical FBC leachate ranges from 9 to 12
while the pH of NSDWR ranges from 6.5
to 8.5. Total dissolved solids and SCu
exceed DWS but are marginally within
10 x DWS if a ten times attenuation/di-
lution factor is assumed. As soil atten-
uation and dilution can play a major role
in reducing leachate pH, TDS, $64, and
calcium, site selection and disposal
facility design are critical factors in
controlling potential ground-water con-
tamination. In addition, contamination
of groundwater due to those trace metal
elements and the microbiological activity
included in the DWS is not expected
because FBC test leachates meet both
the NIPDWR and the secondary drinking
water regulations (NSDWR). Radioac-
tivity, if any, should be similar to that of a
conventional power plant residue.
Impact of RCRA on Siting of
FBC Facilities
The key aspects of RCRA that would
affect the siting of new FBCfacilities are
provisions for hazardous and solid
waste disposal (Subtitles C and D) and
provisions for resource recovery (Sub-
title E). The increased costs of transpor-
tation and disposal of the waste brought
on by RCRA as well as the marketability
and transportation costs of FBC waste
products (should FBC residue be utilized)
will play an important role in siting FBC
facilities. Also, in light of the public
awareness created by RCRA, public
support or opposition is becoming in-
creasingly more important in siting
decisions for fossil-fuel energy facili-
ties.
Impact on FBC Economics
The economics of FBC systems are
sensitive to the total cost of sorbent,
including purchase, transportation, and
disposal. The major increase in disposal
costs resulting from RCRA are expected
to be associated with disposal site
selection, site operation, and solid
residue transportation. The sensitivity
of FBC economics to total sorbent cost
may lead FBC developers to consider
more seriously alternatives for reducing
the total amount of sorbent consumed, or
methods to reduce disposal cost such as
residue processing or utilization, if the
expected increase in the cost of solid
waste disposal resulting from RCRA is
significant. The technical and cost
effects of RCRA on FBC residue disposal
are such that they must be incorporated
in the development of the integrated
FBC system.
Recommendations
This report presents an assessment of
the effect of RCRA on FBC residue
disposal based on current regulations,
some of which were proposed but not
promulgated until this study was com-
pleted. We, therefore, recommend close
review of RCRA development and updat-
ing its impact as new rules and amend-
ments come into existence with specific
attention to the issues that follow.
Hazardous/ Nonhazardous
Waste Identification
This investigation was based on the
proposed RCRA Subtitle C regulations
in the Federal Register of December 18,
1978, in particular Sec. 3001 hazardous
waste identification. Changes in the
following may have an additional impact
on FBC residue disposal, and reassess-
ment may be required:
• EP test and leachate criteria
• Corrosivity/pH criteria
• Reactivity criteria with respect to
exothermic hydration of CaO and
CaS/concentration
• Bioassays, radioactivity testing
methods, and interpretation. Al-
though currently not a requirement,
FBC residues should be investi-
gated for radioactivity and genetic
effects, in terms of both legislative
requirement and better under-
standing of the potential hazard
from a technical point of view.
• Approach to identifying hazardous
waste—signal test versus multi-
stage screening.
In addition, Cr and As in the leachate
from FBC carry-over fines (<15 /urn) and
from the residue resulting from regen-
erative runs should be closely examined
in future investigations to confirm their
classification as nonhazardous.
FBC Disposal Practice
Based on this investigation, FBC
residue is nonhazardous and, therefore,
will be disposed of in a sanitary landfill.
Regulations and disposal criteria for
sanitary landfills under the RCRA Sees.
4004 and 1008 and the CWA will deter-
mine FBC disposal practice.
Since the groundwater criteria are
applicable at the "disposal facility
boundary," which will incorporate ef-
fects of soil attenuation and dilution,
these effects should be investigated
further. These effects are especially
important with respect to leachate pH,
TDS, SO*, and Ca should the secondary
DWS be included as part of the ground-
water criteria in the future. Control
technologies for major leachate variable
(i.e., pH, TDS, S04, and Ca) should be
evaluated in the event that dilution/
attenuation effects might not be suffi-
cient for some specific sites.
Other aspects of disposal, such as the
proper procedures for handling the FBC
residue, disposal site selection, facility
design, construction, operation, and
> U.S. OOVtBHUENTPBINTINO OfFCtlW.757-012/7081
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management, need to be investigated.
Engineering and economic evaluations
of FBC waste disposal should be carried
out, incorporating RCRA requirements
as part of an integrated effort to develop
commercial FBC systems.
C. C. Sun, R. A. Newby, andD. L Keairns are with Westinghouse Research and
Development Center. Pittsburgh. PA 15235.
D. B. Henschel is the EPA Project Officer (see below).
The complete report, entitled "Impact of Resource Conservation and Recovery
Act on FBC Residue Disposal," (Order No. PB 81-150 617; Cost: $11.00,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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