Document ID: EPA-HQ-RCRA-2008-0329-0236
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-01-02T05:00Z

Materials Characterization Paper

In Support of the

Advanced Notice of Proposed Rulemaking –

Identification of Nonhazardous Materials That Are Solid Waste

Biomass - Forest Derived Biomass and Pulp and Paper Residues

December 17, 2008

====================================================================

1.	Definitions of Forest Derived Biomass and Pulp and Paper Residues

The forest products industry generates large amounts of residual biomass
as timber is harvested and manufactured into marketable goods such as
lumber and paper. Forest derived biomass may originate directly from the
forest (logging residues) or from timber processing mills (primary mill
residues). Logging residues include tree tops and small branches that
are typically left uncollected during logging operations. Primary mill
residues consist of bark residues, coarse residues such as chunks and
slabs, and fine residues such as shavings and sawdust generated at
sawmills that process harvested timber. Other forest derived biomass
produced by this industry include residues from woodworking shops,
furniture factories, and truss and pallet manufacturing (secondary mill
residues). These materials have typically been used for their fuel value
in paper operations, as well as disposed of in landfills.

Another source of biomass fuels from the forest products industry is
pulp and paper residuals, including black liquor and wastewater
treatment sludges. Black liquor is generated in the kraft process, which
in 2000 accounted for 83 percent of domestic pulp production. Black
liquor consists of lignin and pulping chemicals used to separate lignin
from the cellulosic fraction of wood. Sludges, both primary and
secondary, are produced from wastewater treatment of process effluents.
Primary sludges originate from primary wastewater treatment operations
(i.e., sedimentation or primary clarification operations) and consist of
wood fiber and inorganic materials, while secondary sludges come from
secondary / biological treatment operations and are composed largely of
microbial biomass.  Note that use of sludges associated with municipal
wastewater treatment (i.e., sewage treatment) plants as fuel is
addressed in a separate paper. 

2.	Annual Quantities of Forest Derived Biomass and Pulp and Paper
Residues Generated and Used

Sectors that Generate Forest Derived Biomass and Pulp and Paper
Residues: 

NAICS 113310: Logging

NAICS 3221: Pulp, Paper, and Paperboard Mills

NAICS 32111: Sawmills and Wood Preservation

NAICS 32121: Veneer, Plywood, and Engineered Wood Product Manufacturing

Quantities and Prices of Forest Derived Biomass and Pulp and Paper
Residues Generated:   

Perlack et al. (2005) estimated production of logging and other removal
residues at 67.1 million tons, 41.9 million tons of which is available
for recovery. This is consistent with Milbrandt (2005), who estimated
total production at 62.4 million tons. McKeever (2004) estimated total
production at 103 million tons with 92.6 million tons available for
recovery. Unlike the other two studies, McKeever included 17.6 million
tons of stumps and limbs. Each of these three studies was derived from
the USDA Forest Service’s Timber Product Output Database.

Total primary mill residue production ranges from 86.8 to 91.4 million
tons (McKeever 2004, Perlack et al. 2005, Milbrandt 2005).

Pulp and paper mills produce the dry biomass equivalent of 52.1 million
tons of black liquor (Perlack et al. 2005) and between 4.2 and 5.8
million tons of wastewater treatment sludges (ITC 2002, Thacker 2007).

Gan (2007) estimates for forest residue a median total market price
(including transport) of $40 per dry ton with a range from $36 to $45.
Current prices for primary mill residues are undetermined, although
there is evidence to suggest that prices have increased substantially in
recent years (e.g., sawdust priced at $25 a ton in 2006 to over $100 per
ton in some markets in 2008) (Millman 2008).

No established commercial market for black liquor exists as it is
utilized within pulp and paper mills.  Prices for sludges are
undetermined.

Trends in Generation of Forest Derived Biomass and Pulp and Paper
Residues:  

Domestic primary mill residue production decreased from 113.4 million
tons in 1990 to 83.4 million tons in 2002 (McKeever 1999, Smith et al.
2004).

Domestic pulp and paperboard capacity decreased at an average annual
rate of 0.7 percent for the period from 2000 to 2007 (AF&PA 2008).

US timber harvest is expected to increase 24 percent by 2050 according
to the Fifth Resources Planning Act Timber Assessment (Haynes and Skog
2002). This increase will be exclusively in the harvest of nonsawtimber
trees.

Perlack et al. (2005) predict that by 2050 increases in availability of
logging and other removal residues by 23 million tons, pulping liquors
by 22 million tons, and primary and secondary mill residues by 16
million tons. An additional 60 million tons of forest biomass may also
be available should widespread fuel treatments for reducing fire hazards
be implemented.

3.	Uses of Forest Derived Biomass and Pulp and Paper Residues

Combustion Uses of Forest Derived Biomass and Pulp and Paper Residues:  

Logging residues, as defined by the Timber Product Output Database, are
not currently collected for combustion or non-combustion use.

Primary mill residues tend to be clean, uniform, concentrated, and with
a low-moisture content (Perlack et al. 2005). They are, therefore,
highly desirable as a fuel as well as for other purposes. Currently,
only between 1.7 and 1.9 million tons are unused (McKeever 2004, Perlack
et al. 2005, Milbrandt 2005).

Approximately 42 percent of all primary mill residues are used as fuel,
including 76 percent of bark residues, 12 percent of coarse residues,
and 56 percent of fine residues (Smith et al. 2004).

Essentially all black liquors produced in pulp and paper operations are
combusted as fuel in pulping liquor recovery furnaces.  These furnaces
provide process energy and recover pulping agents (e.g., sodium sulfide)
used to form fresh cooking liquor (Perlack et al. 2005, Carrott and
Carrott 2007).

In 2002, 21.9 percent of pulp and paper mill sludges were combusted as
fuel (Thacker 2007). An undetermined fraction of sludges was used as a
cement kiln feedstock and as a fuel pellet ingredient.

It has been estimated that thermal oxidation of paper sludge can
supplement as much as 11 to 34 percent of fossil fuel demand for a
medium size mill.  (CANMET Energy Technology Centre 2005.)

Non-Combustion Uses of Forest Derived Biomass and Pulp and Paper
Residues:

Logging residues left on harvested timberland help control erosion,
replenish nutrients, and maintain soil productivity. It is unknown what
fraction can be removed without disrupting these benefits, and this is
likely to vary by location.

Around 56 percent of primary mill residues are used for non-combustion
purposes. This includes 20 percent of bark residues, used largely for
shredded mulches, and 78 percent and 23 percent of coarse and fine
residues, respectively, used for woodpulp, nonstructural panels, and
animal bedding (McKeever 2004, Smith et al. 2004). The specific uses are
driven by economic considerations.

In 2002, 14.6 percent of pulp and paper mill wastewater treatment
sludges were applied to land as a soil conditioner, fertilizer, liming
agent, or mulch (Sippola et al. 2003, Thacker 2007). Around 11.7 percent
had other beneficial uses, including as papermaking fiber, industrial
absorbent, animal bedding, manufactured soil component, compost
feedstock, landfill barrier cover (Zule et al. 2007), acid mine drainage
control cover, building board/fixture (Scott et al. 2000), glass or
lightweight aggregate, and brick or concrete additive (Naik 2004,
Thacker 2007). Sludges are also being considered as a feedstock for
ethanol production (Fan and Lynd 2007).

Quantities of Forest Derived Biomass and Pulp and Paper Residues
landfilled: 

Of the residues described in this section, only pulp and paper mill
wastewater treatment sludges are landfilled to any appreciable extent.

In 2002, approximately 51.8 percent of sludges were disposed of in
landfills or lagoons, typically onsite (Thacker 2007, ITC 2002).  There
is a trend toward reduced disposal of sludges in landfills largely due
to higher landfilling prices and higher fossil fuel prices (Mahmood and
Elliott 2006, de Alda 2008).

Quantities of Forest Derived Biomass and Pulp and Paper Residues
Stockpiled/Stored:

The amount of logging residues that is uncollected is unknown, and these
tend to undergo rapid decomposition after timber harvest.

Black liquors are cycled through pulp and paper mills on a continuous
basis.

Stockpiled/stored quantities of primary mill residues and pulp and paper
mill wastewater treatment sludges are undetermined.

Exhibit 1:  Overview of Generation and Use of Forest Derived Biomass and
Pulp and Paper Residues

Commodity	Annual Quantity Generated 	Annual Quantity Used as Fuel	Annual
Quantity Landfilled	Annual Quantity in Other Uses	Total Quantity
Stockpiled as of 2007

Cement Kilns	Other

--------------- Million Tons ---------------

Logging Residues	41.9 – 92.6 	0 	0	0	0	0

Primary Mill Residues	86.8 – 91.4 	N/I 	35.3 	0	46.4	N/I

Black Liquor	 52.1	0 	52.1	0	0	0

Sludges	4.2 – 5.8	N/I	0.9 – 1.3	2.2 – 3.0	1.1 – 1.5	N/I

N/I =  not idetified

4.	Management and Combustion Processes for Forest Derived Biomass and
Pulp and Paper Residues

Types of Units Using Forest Derived Biomass and Pulp and Paper Residues
as a Fuel:

Forest derived biomass are used as a fuel in a variety of boilers
including Dutch ovens, fuel cell ovens, spreader stokers,
suspension-fired boilers, and fluidized bed combustion boilers (EPA
2003). Scrap wood may be co-fired with other fuels, primarily coal (Mann
and Spath 2001).

In the kraft pulping process, black liquor is combusted as a fuel in a
pulping liquor recovery furnace. Sludges may be combusted as a fuel in
hog fuel boilers, as a supplementary fuel, or in fluidized bed boilers
(Sell 1992).

Sourcing of Forest Derived Biomass and Pulp and Paper Residues:

Logging and primary milling residues are generated during timber harvest
and milling operations.

Black liquor is spent cooking liquor from the kraft pulping process (EPA
1995). Sludges originate from wastewater treatment and, in the case of
mills utilizing discarded paper sources, de-inking processes.

Processing of Forest Derived Biomass and Pulp and Paper Residues:  

Logging and primary milling residues may be chipped or sorted before
combustion so that they can be efficiently burned as fuel. They may also
be dried (cured).

Black liquor undergoes a series of concentrating steps before being
combusted as a fuel.  Weak black liquor is first concentrated to about
55 percent solids by a multiple-effect evaporator system, and then to
around 65 percent by a direct-contact evaporator or indirect-contact
concentrator (EPA 1995, EPA 2002).

Pulp and paper mill sludges typically undergo mechanical dewatering
before being combusted as fuel, with minimum solids content of around 40
percent needed for sustained combustion (Sell 1992, Caputo and Pelagagge
2001). Some sludges are dried to 70 to 95 percent solids (Thacker 2007).

State Status of Forest Derived Biomass and Pulp and Paper Residues Use
as Fuel:

According to state responses to a 2006 survey by the Association of
State and Territorial Solid Waste Management Officials (ASTSWMO 2007),
Iowa and Mississippi have approved the use of pulp and paper residue as
fuel rather than as a waste.  This use in these states has a
pre-approved status, suggesting that a case-by-case approval process for
designation of beneficial use is not necessary for this use (ASTSWMO
2007, p.B-25).  In addition, Michigan reports that in at least one
instance the use of pulp and paper residues as fuel has been approved as
a beneficial use.

As of September 2006, approximately 50 percent of states had renewable
fuels portfolio standards requiring that varying percentages of power
generated within the individual states come from alternative fuels
(including biomass) by a designated future date; several more states
have enacted such regulations since then (DOE 2006).  

5.	Forest Derived Biomass and Pulp and Paper Residues Composition and
Impacts

Composition of Forest Derived Biomass and Pulp and Paper Residues:

The heating values of forest derived biomass and pulp and paper residues
depend upon moisture content. 

The heating value for dry (0 percent moisture) woody materials is
typically between 15.5 and 16.4 million btu/ton (7,750 to 8,200 btu/lb)
(Wright et al. 2006). Wood fired in the lumber and pulp and paper
industries has an average moisture content of 50 percent, with a heating
value of between 9 and 10 million btu/ton (4,500 to 4,980 btu/lb) (EPA
2003, EIA 2008).

The average heating value of dry black liquor is 11.8 million btu/ton
(5,880 btu/lb) (EPA 1995), with a range of 11.6 to 13.4 million btu/ton
(5,820 to 6,680 btu/lb) (Niemelä and Alén 1999). The heating value of
hydrated black liquor as enters the recovery boiler tends to be 20 to 25
percent less (i.e., average 9.1 million btu/ton (4,560 btu/lb) with a
range of 9.0 to 10.4 million btu/ton (4,510 to 5,180 btu/lb)) (Niemelä
and Alén 1999).

A mixture of primary and secondary sludges as generated by the pulp and
paper industry may have a heating value of 3.6 million btu/ton (1,810
btu/lb) at 63 percent moisture (Tarnawski 2004). Sell (1999) and EIA
(2008) describe an average sludge heating value of unknown moisture
content of 12.0 and 7.5 million btu/ton (6,000 and 3,760 btu/lb),
respectively.

Emissions Impacts of Using Forest Derived Biomass and Black Liquor as a
Fuel:

To evaluate the environmental impacts of burning forest derived biomass,
we examined the emissions associated with burning wood in a boiler and
compared these values to the emissions associated with the combustion of
conventional fossil fuels, as summarized in Exhibit 2.  The estimates in
the exhibit suggest that the combustion of wood results in higher PM
emissions than natural gas or distillate oil, but lower PM emissions
than coal or residual oil systems. Therefore, they fall within the range
of typical fuels. The data in Exhibit 2 also suggest that wood results
in lower SO2 emissions than most conventional fuels.  The estimated NOx
emissions associated with wood combustion are similar to those
associated with distillate and lower than the NOx emissions for other
conventional fuels. 

Combustion of black liquor as a fuel in a recovery boiler with an
electrostatic precipitator yields 0.2 lbs. particulate matter per MMBtu.
Combustion without pollution controls emits vastly higher particulate
matter, ranging upwards of 15 lbs./MMBtu. Regardless of pollution
controls employed, SO2 emissions equal 0.6 lbs./MMBtu, while CO
emissions are 0.9 lbs./MMBtu. (EPA 1995, p.10.2-5)

  

	Lifecycle Emissions Impacts: Use of forest derived biomass as a
replacement for traditional primary fuels may eliminate the
environmental impacts associated with extraction and processing of
traditional fuels.  In addition to the emissions impacts of combustion
described above, Exhibit 2 lists the quantities of the total
cradle-to-gate emissions for these fuels based on typical processes in
the United States in the late 1990s, with wood scrap combustion
presented as an indicator of the emissions likely from the combustion of
wood debris.  Note that there may be impacts associated with the
processing of wood debris into useable fuel that are not accounted for
in the values presented in Exhibit 2.  In addition, there may be
alternative uses (e.g., mulching) that are environmentally preferable to
combustion.

  Exhibit 2:  Comparative Impacts of Wood Combustion versus Alternative
Primary Fuels

Pollutant	Wood	Coal	Distillate Fuel Oil	Residual Fuel Oil	Natural Gas

	Combustion	Combustion	Combustion plus Upstream	Combustion	Combustion
plus Upstream	Combustion	Combustion plus Upstream	Combustion	Combustion
plus Upstream

	----------------------------- lb./MMBtu ---------------------------

Criteria Pollutants

PM2.5	-	-	-	-	-	-	-	-	-

PM10	0.019	0.054	0.054	0.011	0.011	0.093	0.093	0.009	0.009

PM, unspecified	-	-	0.246	-	0.012	-	0.012	-	0.004

NOx	0.167	0.482	0.504	0.173	0.234	0.367	0.428	0.301	0.417

VOCs	-	0.006	0.014	0.001	0.363	0.002	0.367	0.009	0.524

SOx	0.008	1.446	1.469	0.209	0.394	1.593	1.781	0.073	1.985

CO	1.511	0.068	0.085	0.036	0.082	0.033	0.079	0.058	0.282

Pb	1.33x10-4	8.93x10-6	9.19x10-6	4.60x10-6	5.61x10-6	5.80x10-5	5.90x10-5
-	2.72x10-7

Hg	-	2.05x10-6	2.14x10-6	1.58x10-6	1.77x10-6	8.67x10-6	8.85x10-6	-
7.18x10-8

Source:

Franklin Associates 1998.

Note:

“-” signifies data not available; may equal zero.

The emission information presented in this table is derived from Life
Cycle Inventory (LCI) data, as compiled by Franklin Associates.   LCI
data identifies and quantifies resource inputs, energy requirements, and
releases to the air, water, and land for each step in the manufacture of
a product or process, from the extraction of the raw materials to
ultimate disposal. The LCI can be used to identify those system
components or life cycle steps that are the main contributors to
environmental burdens such as energy use, solid waste, and atmospheric
and waterborne emissions.  Uncertainty in an LCI is due to the
cumulative effects of input uncertainties and data variability.  

There are several life cycle inventory databases available in the U.S.
and Europe.  For this paper, we applied the most readily available LCI
database that was most consistent with the materials and uses examined.
These LCI data rely on system boundaries as defined by Franklin
Associates, as described in the documentation for this database,
available at:   HYPERLINK
"http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf" 
http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf .  

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Caputo AC, Pelagagge PM. 2001, Waste-to-energy plant for paper industry
sludges disposal: Technical-economic study. J Haz Mat B81: 265-283.

Carrott, PJM, Carrott MML. 2007, Lignin – From natural adsorbent to
activated carbon: A review. Bioresource Technol 98: 2301-2312.

de Alda JAGO. 2008, Feasibility of recycling pulp and paper mill sludge
in the paper and board industries. Resources, Conservation and Recycling
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Fan Z, Lynd LR, 2007, Conversion of paper sludge to ethanol, II: Process
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Haynes RW, Skog KE. 2002, The Fifth Resources Planning Act Timber
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Mahmood T, Elliott A. 2006, A review of secondary sludge reduction
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McKeever DB. 2004, Inventories of Woody Residues and Solid Wood Waste in
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Wall Street Journal, March 3, 2008.

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E, Alén R, Sjostrom E, Eds. Springer-Verlag, New York. 316 pp.

Perlack RL, et al. 2005, Biomass as Feedstock for a Bioenergy and
Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual
Supply (ORNL/TM-2005/66, Oak Ridge National Laboratory, Oak Ridge, TN).

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Sell NJ. 1992, Industrial Pollution Control: Issues and Techniques. 2nd
Ed. Wiley, John & Sons, Inc. 420 pp.

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 Other materials are sometimes identified as Forest Product Industry
(FPI)-derived fuels in the literature;  these include wood products
found in bales of cardboard (old cardboard container, or OCC, rejects),
turpentine and derivatives, biogases recovered from industrial waste
water treatment systems or landfills, methanol from strippers, and
“tall oil” from pine processing.  These are not discussed in detail
here for a variety of reasons.  In some cases (e.g., biogases and
turpentine) they are included in other discussions.  In other cases, it
is not clear whether the materials are already considered part of
another material (e.g., OCC rejects) or are used as fuel with any
frequency (e.g., tall oil). 

 Biomass production estimates are presented on an annual basis.

 The summary table in the reference does not always specify which types
of biomass are included, however, it is likely that woody biomass is
included.  For example, Nevada specifies “wood”.

 Also called the gross or higher heating value.

 We note that the emission factors for wood presented in Exhibit 2
represent averages for wood-burning boilers.  In addition, the wood
reflected in the emissions data may include wood other than forest
derived biomass.

Biomass - Forest Derived Biomass and Pulp and Paper Residues

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