1

MEMORANDUM | 26 October 2012

TO Tab Tesnau, US EPA ORCR

FROM Jason Price, Wiles Kase, and Eric Reker, Industrial Economics, Incorporated

SUBJECT Generation, Management, and Processing of Paper Processing Residuals

Pursuant to Technical Directive 1 issued under Work Assignment B-01, this memo 

summarizes information that IEc obtained on the generation and management of paper 

processing residuals (PPRs). Based on our review of the relevant literature and our 

contacts with industry representatives, this memo presents the following data:

 The quantity of paper processing residuals generated on an annual basis in the 

U.S.

 The portion of paper processing residuals burned as an energy source, 

distinguishing between onsite use and offsite use.

 The quantity of paper processing residuals managed through other (non-fuel) end 

uses such as land application and landfilling.

 The type and level of processing for paper processing residuals used as fuel.

We obtained information on the generation and use of paper processing residuals from 

representatives of the American Forest & Paper Association (AF&PA) and the Recycled 

Paperboard Technical Association (RPTA).1 Based on an informal survey of their 

member companies, these representatives provided the following information with 

respect to the generation and use of paper processing residuals:

 Generation of paper processing residuals: Paper recycling facilities generate 

between 450,000 and 600,000 tons of PPRs (including old corrugated cardboard) 

per year (although these data are not for the most recent year and the amounts are 

likely to have changed with the increase in recycling). These values reflect the 

residuals generated by the initial screening process (i.e., to remove metals), 

materials that do not break down during processing (e.g., paper treated to repel 

water), and fibers too small to be re-used. There are no definitive data on what 

portion of this material is old corrugated cardboard, but a broad array of types of 

recovered fiber, such as old magazines, old newsprint and office paper, are 

increasingly used at paper recycling mills as recovery rates approach 70 percent 

of all paper produced.

 

1 The information provided in this section is based on personal communication with Tim Hunt of the AF&PA and Amy Schaffer 

of the RPTA, October 19, 2012.

BACKGROUND

GENERATION AND USE 

OF PAPER PROCESSING 

RESIDUALS
2

 End uses: Roughly 30 percent of paper processing residuals (approximately 

135,000 to 180,000 tons) are burned for their fuel value. Between six and ten

companies currently burn paper processing residuals in 15 to 20 different mills. 

At mills that burn paper processing residuals as a fuel onsite, the percentage of 

this material burned ranges from 55 to 100 percent of the PPRs generated onsite. 

In addition, at some mills, paper processing residuals provide up to 20 to 25 

percent of the total solid fuel energy consumed onsite. Thus, paper processing 

residuals represent a significant source of energy for these facilities. PPRs are 

not burned during solid fuel boiler downtime or when combustion conditions and 

fuel availability dictate a different mix of solid fuels to meet boiler performance 

characteristics. The 70 percent of PPRs that are not burned for energy are mostly 

landfilled, with minimal amounts used for land applications.

 On-site versus off-site usage: Of the roughly 30 percent of PPRs burned as a 

fuel, a large majority is burned on site. The representative from the AF&PA 

estimates that no more than 5 percent of PPRs are burned offsite. As noted

above, only 15-20 of the 100+ paper mills across the U.S. burn PPRs as fuel. 

Many facilities (particularly recycle mills) use natural gas in their boilers and are 

unable to use solid material as a fuel source. Unless an arrangement can be made 

with another boiler in the area to use the material, the PPRs generated at facilities 

that use natural gas boilers are landfilled. 

IEc reviewed several sources related to the nature and extent of processing that is 

regularly performed on PPR prior to use as a fuel, including public comments submitted 

to the EPA under the NHSM Rule, journal articles, and industry websites. Excluding 

public comments on the NHSM rule, limited information was readily available on the 

subject, primarily focusing on paper processing in Europe and the United Kingdom. We 

were able to obtain one peer reviewed journal article on the subject, which did not contain 

information on PPR processing in the US. However, the information in this article, which 

focuses on processing in Europe, describes processing measures for PPR similar to those 

found in the public comments. In conducting this research, we identified processing 

information for both recycling process residuals and pulp & paper sludge, which are 

defined as follows:

 Recycling process residuals (RPR): paper fiber that is unusable (due to 

impurities, fibers too small for recycling process) resulting from the recycling 

process.

 Pulp and paper sludge (PPS): pulp and paper wastewater treatment 

residuals.

To summarize, various methods are used to dewater and appropriately size PPR for use as 

fuel. PPS generally requires more intensive processing than RPR, particularly dewatering.

RECYCLING PROCESS RE SIDUALS

According to the public comment submitted to the EPA under the NHSM Rule Package 

by nine major industry representatives, including the AF&PA, the American Wood 

Council, and the Biomass Power Association, some processing occurs before burning 

PROCESSING OF PAPER 

PROCESSING RESIDUALS
3

RPR for energy.

2

 Processors generally use a slotted screen to select cellulosic fibers that 

are too small for paper production, which are considered to have adequate heating value. 

Some plants will then use hydraulic presses to squeeze unwanted moisture out of the 

residuals before shredding the material to the optimal size for combustion.3

The measures for processing of RPR described in AF&PA’s comment are corroborated in 

the literature we were able to obtain. The literature states that to select the fibers too small 

for paper production or the recycling process, plants use a slot screening mechanism.4

Infrequently, some plants may apply a drying process to these residuals before firing 

them, but the minimal processing needed to convert these materials into valuable fuel is 

generally an attractive feature.5

PULP AND PAPER SLUDGE (PPS)

Information submitted in the public comment from AF&PA mentioned above indicates 

that significantly more processing is required before PPS can be used as a fuel. The 

overwhelming majority of pulp and paper mills remove water from PPS prior to use as a 

fuel (or in other applications), using belt and screw presses, steam heated filter presses, 

and sometimes steam heated rotary driers for additional dewatering.6Information 

submitted by one mill describes the processing of PPS in its plant: 

“Process waters carry the fibers rejected by the screens and cleaners and the fines to 

the water treatment system. Gravity settling in the primary clarifier removes the 

solids from the process water. The settled solids, called clarifier WWTR, are pumped 

from the clarifier to the filter press. Water is squeezed out of the WWTR and it is 

hauled to the fuel pile for the multi-fuel boiler.”7

Another mill process is as follows:

“The mill generates combined primary and secondary WWTR using three parallel 

rotary screen thickeners (RSTs) followed by screw presses. The RSTs and screw 

presses are optimized to provide the highest possible solids content. The dewatered 

WWTR is stored on a pad, then transferred to the boiler fuel reclaim area, and 

 

2

American Forest & Paper Association, et al., public comments submitted on the Rule to Categorize Non-Hazardous 

Secondary Materials That Are Solid Waste (EPA-HQ-RCRA- 2008-0329) and Commercial and Industrial Solid Waste Incineration 

Units: Reconsideration and Proposed Amendments (EPA-HQ-OAR-2003-0119). Comment ID EPA-HQ-RCRA-2008-0329-1946-A1. 

February 21, 2012. P. 55.

3

American Forest & Paper Association, et al., public comments submitted on the Rule to Categorize Non-Hazardous 

Secondary Materials That Are Solid Waste (EPA-HQ-RCRA- 2008-0329) and Commercial and Industrial Solid Waste Incineration 

Units: Reconsideration and Proposed Amendments (EPA-HQ-OAR-2003-0119). Comment ID EPA-HQ-RCRA-2008-0329-1946-A1. 

February 21, 2012. P. 55.

4 Gavrilescu, D. “Energy from biomass in pulp and paper mills.” Environmental Engineering and Management Journal, Vol. 7, 

No. 5, 537-546. September/October 2008. P. 540.

5 Gavrilescu, D. “Energy from biomass in pulp and paper mills.” Environmental Engineering and Management Journal, Vol. 7, 

No. 5, 537-546. September/October 2008. P. 542.

6

American Forest & Paper Association, et al., public comments submitted on the Rule to Categorize Non-Hazardous 

Secondary Materials That Are Solid Waste (EPA-HQ-RCRA- 2008-0329) and Commercial and Industrial Solid Waste Incineration 

Units: Reconsideration and Proposed Amendments (EPA-HQ-OAR-2003-0119). Comment ID EPA-HQ-RCRA-2008-0329-1946-A1. 

February 21, 2012. P. 53.

7

American Forest & Paper Association, et al., public comments submitted on the Rule to Categorize Non-Hazardous 

Secondary Materials That Are Solid Waste (EPA-HQ-RCRA- 2008-0329) and Commercial and Industrial Solid Waste Incineration 

Units: Reconsideration and Proposed Amendments (EPA-HQ-OAR-2003-0119). Comment ID EPA-HQ-RCRA-2008-0329-1946-A1. 

February 21, 2012. P. 48.
4

transported to the fluidized bed boiler, along with hog fuel, on a series of 

conveyors.”

8

In their public comment submitted to the EPA under the NHSM Rule Package, Verso 

Paper Corp. states that they employ an activated sludge treatment (AST) process and 

secondary holding tanks to separate out cellulosic fibers from wastewater. According to 

the comment:

“After excess secondary sludge is removed from the treatment loop, at three of 

Verso’s mills it is mixed with primary sludge in blend tanks prior to being dried on 

belt presses to a suitable moisture level for burning or other uses. Sludge is 

introduced into the mills’ solid fuel feed systems by means of conveyers, where it 

becomes thoroughly mixed with other fuels in the conveyer systems before being 

introduced into the mills’ combination boilers. At one mill, primary sludge is dried 

separately by means of screw presses, while secondary sludge is dried using a belt 

press. The two fuels are fed separately by conveyers onto the mill’s main solid fuel 

conveyer, which transports the bark/sludge mixture to a surge bin. The fuel is passed 

through a “waste heat dryer,” where it is briefly exposed to boiler flue gas before 

being fed into the combination boiler.”9

As with RPR, the literature we were able to obtain corroborates the description of the 

level and type of processing of PPS provided in public comments. Gavrilecu (2008) states 

that maximum mechanical dewatering of sludge prior to combustion is essential. The 

paper also claims that recyclers and paper processors may mix PPS with dryer secondary 

materials to improve energy output.10 Increasingly, PPS will undergo fluidized bed 

combustion, as it works particularly well with the wet sludge produced in de-inking mills. 

Gavrilescu states that, “in this process, air is bubbled through a bed of inert material 

(usually sand or limestone), which greatly improves the combustion process.”11 Plants use 

varying processing methods for each type of PPS produced in “the common effluent 

treatment processes” (de-inking sludge vs. sludge from paper mill waste-water treatment 

plants, effluent sludge, etc.).12

 

8

American Forest & Paper Association, et al., public comments submitted on the Rule to Categorize Non-Hazardous 

Secondary Materials That Are Solid Waste (EPA-HQ-RCRA- 2008-0329) and Commercial and Industrial Solid Waste Incineration 

Units: Reconsideration and Proposed Amendments (EPA-HQ-OAR-2003-0119). Comment ID EPA-HQ-RCRA-2008-0329-1946-A1. 

February 21, 2012. P. 48.

9

Verso Paper Corp., public comments submitted on the Rule to Categorize Non-Hazardous Secondary Materials That Are Solid 

Waste (EPA-HQ-RCRA-2008- 0329) and Commercial and Industrial Solid Waste Incineration Units: Reconsideration and 

Proposed Amendments (EPA-HQ-OAR-2003-0119); and National Emission Standards for Hazardous Air Pollutants for Major 

Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters: Reconsideration and Proposed Amendments 

(EPA-HQ-OAR-2002-0058). Comment ID EPA-HQ-RCRA-2008-0329-1942. February 20, 2012. P. 6-7.

10 Gavrilescu, D. “Energy from biomass in pulp and paper mills.” Environmental Engineering and Management Journal, Vol. 

7, No. 5, 537-546. September/October 2008. P. 541.

11 Gavrilescu, D. “Energy from biomass in pulp and paper mills.” Environmental Engineering and Management Journal, Vol. 

7, No. 5, 537-546. September/October 2008. P. 541.

12 Gavrilescu, D. “Energy from biomass in pulp and paper mills.” Environmental Engineering and Management Journal, Vol. 

7, No. 5, 537-546. September/October 2008. P. 542.