pulp and paper industry's diverse organics stream

WIDE RANGE OF FEEDSTOCKS

PULP AND PAPER INDUSTRY'S DIVERSE ORGANICS STREAM

By-products from the pulp and paper industry fall into many categories - from industrial sludges that are land applied or composted t o postconsumer fibers that are part of organics composting programs.

Conni Kunzler

T HE PULP and paper industry gen- erates a variety of organic residuals - from paper mill solids and wood ash to postconsumer recovered fiber - that are suitable for beneficial use via land application and com~osting. In 1999,47.3 mil-

lion tons of paper wereUrecycled, 'primarily into new paper and paper products. Over three million tons were used beneficially for land application and just over 300,000 tons were recovered via composting.

The pulp and paper industry is repre- sented by all types of mills - from those with a feedstock that is 100 percent recovered paper to those that use only wood fiber, and every combination in between. In 1999, recovered fiber's share of total fiber con- sumption a t U.S. mills was 36.5 percent. This is up from 36.1 percent in 1998 and 25 percent in 1988.

Production processes a s well a s paper grade manufactured vary greatly among mills. Therefore the types and amount of residuals produced also vary. Typically, however, pulp and paper mill by-products include wastewater treatment residuals (commonly referred to as sludge), wood ash, causticizing area waste, secondary fiber rejects and paper mill rejects.

The National Council for Air and Stream Improvement (NCASI), a nonprofit environ- mental research organization funded by the forest products industry, gathers data every five years on the solid waste management

More than three million tons of paper and pulp residuals (closeup view shown at left) were beneficially used for land application in 1999, with 300,000 tons recovered via composting.

practices of the U.S. paper industry (2000 data will be available in 2002). In 1995, according to NCASI, the pulp and paper industry produced about 5.8 million dry tons of wastewater treatment residuals. Of this, about half was beneficially used - 26 percent recovered for energy, 12 percent directly land applied, and one percent composted.

Wastewater treatment residuals include solids from primary treatment, secondary treatment or both combined. Primary treatment solids vary in composition depending on the type of mill but can include fiber, clay, inks and dyes, boiler ash, and other materials removed in separation of solids from raw wastewater. Secondary solids are comprised of microbial biomass from the biological treatment of wastewater.

Approximately 2.8 million tons of wood ash were produced in the pulp and paper industry in 1995; 28 percent was used for land application and construction, and less than one percent was composted. Higher residual ash content is more likely at deinking mills and those that produce a coated paper. Wood ash comes from the use of wood as a fuel in mill power boilers. Coal and other solids such as paper mill sludge or even tires also may be burned, resulting in a multifuel ash.

Causticizing area waste - lime mud, green liquor dregs, and slaker grit - are produced a t kraft pulp mills a s a chemical recovery processing by-product. These residuals have a high pH (8.4 to 13.0) and a lot of calcium. About 100,000 tonslyear are applied directly to agricultural/silvicultural land. About 1,500 tons were used in compost in 1995.

Paper mill rejects include dirt, other con- taminants, and some short fibers. These residuals do not include "broke," which is paper trimmings and off-spec paper often put right back into the papermaking process. In 1995, approximately 17,000 tons of paper mill rejects went to composting.

BENEFICIAL CHARACTERISTICS OF RESIDUALS Land application of pulp and paper resid-

uals provides plant nutrients and organic

On slopes in the Northwest (far left), juniper trees - which are considered a nearly unusable weed that can only be cut and left to burn or rot - are processed with a portable band mill (left). David Sintay (below) stands alongside furniture and paneling made from juniper wood that has been resawn and dried.

a way could be found to harvest the fiber economically. Juniper, explains Willis, is a beautifully grained, strikingly colored, hard wood that looks much like Australian Cypress but is generally a bit lighter and much less expensive. The wood dries well and, once dry, does not expand and shrink excessively. It also takes stains and finish- es well.

Despite its beauty and usefulness, harvest levels have traditionally been low. "That's mostly," Willis says, "because the tree is difficult to harvest and mill economically. The complication is that it is difficult or impossible to assess quality until a log is actually processed." To obtain good lumber, logs must be milled soon after felling, before thev drv excessivelv and unevenlv.

unit with elGctronic

rotating the logs, and sawing them into pre- cisely sized dimension lumber. The portable saw is moved to an area scheduled for juniper removal, where select trees are dropped, logs removed, and cants are sawn. They are taken to the company's processing facilities in John Day, where lumber is resawn and dried then turned into high quality furniture, floor- ing, paneling, and other products.

MATERIALS HANDLING METHODS By breaking down the logs where they are

harvested, the quality of the potential lumber can be checked on-site so only good wood is transported to the secondary processing facil- ity. Unusable material is stacked and left be- hind to provide wildlife habitat. The cants, which consist of almost entirely usable fiber, are now valuable raw materials that can be economically transported and processed. The application may have tremendous environ- mental consequences in, for example, the dangerously overgrown pine forests of the in-

and Dewatered

LIQUID SYSTEM ) ARRANGEMENTS with Direct Injection of Soil Compatible Waste Product

matter to soils and crops. Table 1 lists the concentrations of major nutrients for selected pulp and paper mill residuals. Municipal biosolids (wastewater treatment sludge) is included for comparison.

As the table shows, the paper residuals have relatively low concentrations of most nutrients (calcium and magnesium are exceptions). However, the nutrient concentrations depend on the source of the residuals (primary versus secondary sludge) and the specific mill. In general, primary sludges have lower nutrient concentrations than secondary sludges. The wastewater treatment processes t ha t generate secondary sludge concentrate some nutrients. In addi- tion, nutrients, particularly nitrogen, are commonly added to aid in wastewater treatment. Of the causticizing residuals, green liquor dregs contain the highest nutrient concentrations (except calcium). All causticizing residuals tend to have a high calcium concentration and a high pH. With their high pH, causticizing residuals and wood ash serve as good liming agents.

Perhaps the primary value of pulp and paper mill residuals to soils is the organic matter. Most pulp and paper residuals contain moderate to high levels of organic matter. Again, i t depends on the mill and type of residuals produced. Exceptions include wood ash and a few other residuals with a high ash content. The organic matter im-

C:N ratio. Therefore application rates must be limited and/or supplemental fertilizer needs to be supplied. The high C:N ratio is one reason in favor of composting pulp and paper mill sludge (composting lowers the C content).

The important composting characteristics of several pulp and paper mill residuals are listed in Table 2. Excluding wood ash, these residuals have a n ideal to slightly high moisture content for composting. Again excluding wood ash, the electrical conductivi- ty (EC) is very low but the pH varies greatly. C:N ratios vary widely depending on the source of the residuals. Because of the low nitrogen concentration (high C:N ratio), pulp and paper residuals are composted with high nitrogen feedstocks. Several composting facilities include wood ash in their feedstock mixture to decrease the moisture and increase the mineral content of the mix. Wood ash is also thought to reduce odors by adsorbing odorous compounds. (See "Wood Ash Finds Niche In Biosolids Composting," January, 1997).

COMPOSTING WASTEWATER SOLIDS William Thacker, a senior research engi-

neer a t NCASI, is conducting a survey on the experience with composting paper mill by-products. According to his research, about two dozen mills have one or more materials composted. In most cases the materi-

Depending upon the specific mill, pulp and paper residuals contain moderate to high levels of organic matter with relatively low concentrations of most nutrients.

Table 1. Major nutrients in selected pulp and paper mill wastewater sludges and causticizing residuals

Nltrogen (N) Phosphorus (P) Potassium (K) Calcium (Ca) Magnes~um (Mg) Sulfer (S) Materlal Range Mean* Range Mean* Range Mean* Range Mean* Range Mean * Range Mean*

- - - - - - Nuhent concentrations ~n g/Kg 5 -

Primaty sludge1 0.51-9.0 2.7* 0.01-4.0 1.6' Secondary sludgei 6.2-87.5 23.3* 0.42-16.7 4.2* Combined p&sl 1.1-59 8.5* 0.1-25.4 0.67* 0.12-10 2.2* 0.28-210 14.0* 0.2-19.0 1.55* 0.2-20.0 4.68* Combined p&s (Wl)z 1.4-41 29 1.3-5.8 3.4 0.37-6.0 1.37 2.7-90.2 29.5 0.11-1.0 0.65 - - All sludges (ME)3 0.1-61 1.1* 0.01-3.1 0.85* 0.08-3.4 0.46* 0.001-82 4.2* 0.05-3.7 1.8* 0.3-6.5 0.5* All sludges (AL)4 3.0-15.5 8.76 0.19-2.57 1.2 0.15-2.65 0.96 13.0-148 60.0 0.72-5.07 2.30 0.1-10.5 4.1 Lime muds1 2.0-3.0 1.78 1.07-5.7 2.83 ~0.2-1.16 0.44 281-499 379 2.35-10.4 6.23 0.5-4.0 2.0 Green liquor dregs1 1.6-4.2 2.7 0.13-1.17 0.67 0.33-11.95 4.63 35-322 194 5.85-42.7 22.65 6.2-21.7 14.2 Slaker grits1 1.3-5.0 0.67 0.23-1.68 0.81 1.32-5.98 2.70 340-391 364 3.7-10 7.17 0.2-2.9 1.2 Municipal biosolids <I .O-210 32.0 <1 .O-150 14.0 0.2-650 2.3 1.0-250 27.0 0.3-25.0 4.0 6.0-15 11.0 (for comparison)

~ - ~ ~~~ - - - . -

Adapted from 'Composition and land application ofpaper ma~iufacturing residuals," Cainberto et. al, 1997. Agricultural Uses of By-products and Wastes, Eds: Recheigl and MacKinnon. American Chemical Society Notes: *Indicates the median value. Otherwise the mean value is given; 'From NCASI survey of 54 mills; range and median for K, Ca, Mg and S are for all sludges - primary, secondary and combined; 2From survey of 7 mills in Wisconsin combining primary and secondary sludges; 3From survey of 8 mills in Maine, all sludges; 4From survey of 7 mills in Alabama, all sludges; 5To convert g/kg to percent, divide by 10

proves soil structure, soil biology, and moisture retention and helps to prevent nutrients from leaching.

However, because of the low nutrient concentration, land application of paper mill residuals can lead to temporary immobiliza- tion of nutrients in the soil. This is particularly important for nitrogen. The carbon to nitrogen (C:N) ratio of pulp and paper residuals is typically high (see Table 2), reflecting the fact that these residuals originate from wood products. Secondary sludge, with more nitrogen, tends to have a more moderate

a1 is sludge. "Much of the activity is in the Northeast, where there are smaller mills and higher landfill t ipping fees," says Thacker. "There's not a big variety of by- products being composted a t the moment, and while most are sending the materials to a composter, a few mills are composting on- site." Thacker's study for NCASI is due out in spring 2001.

One of the paper companies composting i t s was tewater t r ea tmen t residuals i s Menasha Corporation (see "Bringing Com- posted Feedstocks To Market," October,

At its Otsego, Michigan mill, the Menasha Corporation operates a 50-acre compost site that produces a soil amendment from sludge and hardwood fines, and a topsoil made from sludge and sand. "We feel good that we have a green process here," says a Menasha manager. "It's true cradle to grave, and it's good stewardship."

Table 2, Composting characteristics of pulp and paper mill residuals*

Moisture C/N C N EC Asht (% wet wgt,) Ratio (% dry wgt.) (% dry wgt.) pH (dS/m) (% dry wgt.)

Paper niill sludge1 - - - - 7.7 0.2 -

Secondary paper mill sludge2 - 41.5 50.6 1.12 - - -

Bleached newsprint pulp & paper mill sludges 71.4 218 48 0.22 4.6 0.59 1.64 Paper mill sludge4 76.9 218 48 0.22 4.4 0.2 2.1 Mixed deinking, primary & secondary5 40 to60 89 32 0.36 - - 49 Primary paper mill sludge (wood fiber wastep 74 - - 0.3 6.1 - - Primary paper mill sludge - bleached kraftlNSSC7 - >I68 16.8 <0.1 9.4 - 69.3 Paper mill rejects - bleached kraftlNSSC7 - >357 35.7 t0.1 8.6 - 3.2 Mixed primary, secondary and de-inking sludges8 67 48 42 0.87 - - 25 Short paper fiber - low ash sample9 61 238 31 0.14 8.1 - 45 Short paper fiber - low ash sample9 52.4 560 30 0.05 9.3 - 43 Short paper fiber - high ash sample9 41 264 17 0.06 10.5 - 80.2 Wood ash10 31 93 18 0.2 12 13 -

Wood ash7 - >76 7.6 <0.1 12.2 - 86.4 - - - ~ ~ -- - -

'Sources (all of the references are from the Journal of Compost Science and Utilization, published by The JG Press, Inc. V01ume:lssue are indicated in parenthesis) 'Chong and Cline, 1994; (23); 2Evanylo and Daniels, 1999 (72); 3Jackson and Line, 1997 (5:3); 4Jacobsen & Line, 1997 (5:l); 5Sesay et al., 1997 (5:l); fiLine, 1995 (3:l); 'Campbell et al., 1995 (37); *Larsen & McCartney, 2000 (8:2); Fkinci et a/, 2000 (8:2); roCampbel1 et a/., 1997 (5: l ) tValues for % ash can be used to roughly estimate % organic matter by subtracting %ash from loopercent, e.g. paper mill sludge has an ash value of 2.1 percent (dry weight) so the estimated organic matter is 97.9 percent (dry weight)

1998). At its Otsego, Michigan mill, which produces corrugated medium, Menasha has partnered with Jim Glas of Renewed Earth, Inc. to compost about half of the 60,000 cu- bic yards of paper mill sludge produced each year on a 50-acre site next to the mill. The other half is land applied.

"We haven't landfilled one drop of sludge since 1974," says Dave Merkel, technical manager with the Menasha Paperboard Di- vision. "We started experimenting with composting in 1992 and then worked on per- mitting, and went into full-scale production about four or five years ago." The operation produces a soil amendment from paper mill sludge and hardwood fines, and a topsoil made from sludge and sand. "Our products are sold mostly to landscapers, golf courses, departments of transportation, and a host of other government agencies and private businesses," says Merkel.

The mill, which uses both recycled corrugated and wood chips to manufacture its end product, turns out a sludge that is beneficial and highly conducive to composting. "It has worked out well for us," says Merkel, "and we feel good that we have a green process here. It's true cradle to grave and it's good stewardship."

COMPOSTABLE POSTCONSUMER PAPER According to the American Forest & Pa-

per Association (AF&PA), over 6.5 million tons (less scrap) of compostable postconsumer paper and paper products are produced annually. This includes paper yard bags, waxed corrugated containers, milk cartons, paper plates, cups, napkins, and towels. A study conducted by BioCycle for AF&PA in 1999 concluded that 300,000 to 325,000 tons of postconsumer paper were composted. This is up about 60 percent from the 1998 estimate of 200,000 tons.

The estimate includes paper composted in the municipal and institutional, industrial and commercial sectors as well as paper yard bags.

Waxed corrugated cardboard from super- markets, meat packing plants, produce dis- tribution centers, and furniture and appli- ance distributors accounts for much of what is composted. To help link these sources to composters able to take such fiber, AF&PA established a n online directory in 1998 (www.afandpa.org). The searchable directory contains contacts for nearly 100 composters who accept paper feedstocks, a s well as other categories of processors. Com- posting and other recycling sites can be added online.

The volume of waxed boxes destined for composting is likely to decrease slightly in the future. "New innovations in the paper industry are eliminating the need for wax coatings in some applications," says Dave Stuck, executive director of the Container- board and Kraft Paper Groups a t AF'&PA. "For example, when transporting broccoli, there is a new innovative corrugated box that eliminates the need for icing and therefore the waxing of the box." Nonwaxed boxes can be recycled with other corrugated, thus eliminating the need for an alternative management method such as composting.

Milk cartons, generated primarily a t schools and homes, can be recycled a t about a half dozen mills across the country. Many communities and schools, however, are not near a mill that accepts beverage cartons, and these are finding a home a t composting facilities. For example, the city of Plano, Texas collects beverage cartons from seven schools and 20 businesses. Organics are picked up daily by an automated, doubled- sealed truck and taken to the city's composting site 45 minutes away. According to

Heidi Smalley with the city of Plano, when the composting program is fully implement- ed, organics will be collected from 70 schools and businesses.

A 1999 AF&PA study conducted in con- junction with Dartmouth College's composting program showed that high quality compost can be produced using laminated paper products, including milk cartons, as feedstock. The study also found that paper products such as cups, plates, and bowls recovered from an inst i tut ional food service setting degrade a t a rate consistent with other organic constituents.

Napkins, towels, tissue, and other soiled papers - as well a s paper beverage cartons - also are included in residential organics collection programs. Residential food, soiled paper, and yard trimmings com- postables collection is part of the city of San Francisco's "Fantast ic Three" program which started in April, 1999 and has grown to more than 15,000 households plus businesses (see "San Francisco Takes Residen- tial Organics Collection Full-Scale," Febru- ary, 2000). The program is anticipated to expand city wide to more t han 128,000 households over the next three-and-a-half years. "The paper products provide a carbon rich balance to the feedstock and help absorb liquids," says Jack Macy, organics recycling coordinator for the city of San Francisco. "In fact, we encourage people to Wrap their food in newspaper or used paper bags to keep the containers for composta- bles clean."

Some communities also are composting other types of papers, often for lack of a recycling market within an economical distance. For example, a pilot program in Austin, Texas that began in September is collecting boxboard at curbside along with yard trimmings for composting. "We have a market for our other papers, but not for this, so we are having residents put out their boxboard in paper grocery bags along side any yard trimmings they might have," says Sam Farias, senior planner for the city of Austin. "We have been testing the composting of this material with the yard trimmings."

WOOD RESIDUES As a result of technological innovations

o ~ e r the past 20 years, about 95 to 99 percent of wood fiber that goes into mills is uti- lized. Secondary fiber that is not processed into products is generally used as fuel. "The pulp and paper industry is not really a source of scrap wood for composters or other processors," says Brad Williams, manager of AF&PA's Timber Management and Supply group. Therefore, t he primary sources for used and scrap wood are the municipal waste stream, construction and de- molition activities, deconstruction, pallets, primary timber processing, and land clcar- ing for utilities, highway construction: and other projects.

According to the U.S. Department of Agri- culture's Forest Products Lab in Madision, Wisconsin, 162 million tons of waste wood

-- -- - --

A 1999 AF&PA study showed that high quality compost can be produced using laminated paper products, including milk cartons, as feedstock.

were generated in 1998, (see "How Woody Residuals Are Recycled in t he United States:" December, 1999). About 132 million tons were recovered, combusted, or not usable. Another 29 million tons were available for recovery. To help communities and businesses with wood residues and by-products connect with processors that recover these materials and use them for new products, in 1996 AF&PA initiat,ed the National M'ood Recj~cling Directory. Updated in 1999, this online directory (urw~r.afandpa.org) contains over 700 processors.

DIVERSION ORIENTATION The paper industry has always seen land

application, composting and other beneficial uses for pulp and paper as great options for paper fiber that cannot be traditionally recycled. "The goal. really, is to keep fiber out of t he landfill and pu t i t to use," says Th7illiams. The most accessible fiber streams - and the most amenable for composting - are wastewater treatment residuals and wood ash, and postconsumer paper and paper products. The value and precedent for land application and composting these materials continues to grow. They have proven to be a good source of carbon, organic matter and nutrients.

Conni Kunzler is an independent consultant working wit17 the American Forest & Paper As- sociation. Slze is based in Arlington, Virginia.

I I Request for Proposals I I Bl~~cs te ln Solid \.\'aste Agency and the lo\va Dcpal-tment of Katural Resoul-ces \ \ , i l l re\-ie\\. qualifications of conlpanics to PI-ovide consulting ser\,iccs I-elated to the analysis of the fcasibilit!, of anael-obic d ~ g e s t ~ o n of orgaliic solid \\.astes In Linn County lo\\-a.

Scope of the Feasibility Stud!.: Bluestem is seeking a multif:iccted and 111o1-ough fea sibilit\- study of anaerobic digestion (AD) in Linn Count!. that \\.ill address a wide scope, including but not limited to the iollo\\.ing items:

t.1-aluation of the success and railur-e of .AD systems in otlicl- localities; anal\,sis of digestel- design options; idcntific,~tion of organic Ivastcs in Linn Count!- huitahle lol- ,411; assessment of the impact of . \L) on the ovc~-all \\.astt' mdnagement s!.stem: potential qua l~ ty? quantity 'ind uses fol- .-\I) h!-pl-otiucts: siting ' ~ n d pel-mitting issues o p p o r f i ~ n ~ t i c s and options for fundinp; anal!.sis o i cionomic iaitors iniludlng isl3ital anti c)perdtio~ial costs and o\\.nc~.ship alicl.nati~.es.

I I I:LII-tlicr details '<nd I-equil-cments ma), be o b t a ~ n e d online 'It \ \ \ \~~\ . .hlucstenl .o~-g 01-

b!. callins leli .\l!.rom, 13li1estcn-i \l'aste I'lanncr, at 3 19.398.12;S I/ I'rol-x>sc~ls i 1 01-iginal and 6 copies I must he I-eceived b! -1:OOi'nl. Central Standard I r ime o n .-\ugl~st 17111, 2001 (fasts not acce~tc t l i to 111c follo\\ing:

Bluestem Solid IVaste Agency Att11: Jeff RIyroln

6301 Kirkwood Rlvd., S\I: P.O. Box 2068, Cedar Rapids, 1A 52406

pulp and paper industry's diverse organics stream

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