Chapter 12
Composition and Land Application of Paper Manufacturing Residuals Downloaded by PENNSYLVANIA STATE UNIV on September 6, 2012 | http://pubs.acs.org Publication Date: July 1, 1997 | doi: 10.1021/bk-1997-0668.ch012
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J. J. Camberato , E. D. Vance , and Α. V. Someshwar 1
Faculty of Soils and Land Resources, Clemson University, 2200 Pocket Road, Florence, SC 29506-9706 National Council of the Paper Industry for Air and Stream Improvement, Box 141020, Gainesville, F L 32614-4501 2
Paper manufacturing generates sludge and causticizing residuals that can be used as soil amendments to enhance productivity of agricultural systems while maintaining high environmental quality standards. Crop response to land-applied sludge depends largely on its Ν content, and supplemental Ν is sometimes required to improve its effectiveness as a soil amendment. Slaker grits, green liquor dregs, and lime mud have high alkalinity and are effective agricultural limestone substitutes. Paper manufacturing residuals are generally low in metals and organic compounds of environmental concern. Successful utilization of residuals necessitates an accurate measure of nutrient content and alkalinity and a uniform, timely, and appropriate application to a suitable, well-managed soil-plant system.
Residuals from paper manufacturing include waste treatment sludges, bark and combination bark boiler ashes, lime mud, slaker grits, and green liquor dregs. Estimates of solid waste generation for 26 USA Kraft pulp and paper mills were obtained by the National Council of the Paper Industry for Air and Stream Improvement (NCASI) during two recent life cycle inventory surveys (Table I). Since nearly 80% of the chemical pulp produced in the USA isfromthe Kraft process, these data are a good representation of current pulp and paper industry residuals from chemical pulping. Boiler ash and sludges constitute the majority of pulp and paper mill residuals. The causticizing operations involved in the Kraft pulping and recovery process generate alkaline residuals such as lime mud, slaker grits, and green liquor dregs. These residuals are not produced in other forms of chemical or non-chemical pulping. Estimates of sludges produced in other forms of chemical pulping (e.g., sulfite and semi-chemical) and non-chemical pulping (e.g., direct recycled, deinking, groundwood, and nonintegrated) were obtained during a 1989 survey (Table Π). © 1997 American Chemical Society
In Agricultural Uses of By-Products and Wastes; Rechcigl, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.
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AGRICULTURAL USES OF BY-PRODUCTS AND WASTES
Table I. Summary from NCASI Surveys of Residuals Generated at Thirteen Unbleached Kraft and Thirteen Bleached Kraft USA Pulp Mills No. Mills
Mean
Median
Max.
Min.
kgwet/ODMTP
22
64.2
49.2
268.8
0.5
Combustion Ashes
kg/ODMTP
19
41.2
33.8
107.3
2.2
Lime Mud or Sludge
kg/ODMTP
12
71.9
46.0
284.2
0.9
Slaker Grits and Dregs
kg/ODMTP
18
19.2
11.1
66.9
0.4
Woodwaste, Bark Grit
kg/ODMTP
10
26.9
13.7
90.2
0.6
0
kg/ODMTP
20
29.9
20.3
204.1
0.5
Residual
Units 8
Downloaded by PENNSYLVANIA STATE UNIV on September 6, 2012 | http://pubs.acs.org Publication Date: July 1, 1997 | doi: 10.1021/bk-1997-0668.ch012
Wastewater Sludges
b
Other Solid Residuals
*Note that some mills bum their sludge in boilers, thus the amount reported may be less than the total generated. ODMTP - oven-dry metric ton of pulp. May include waste paper/paperboard, mill trash, construction debris, and cinders. Source: NCASI, unpublished data, 1993-1995. b
c
Table Π. Pulp and Paper Mill Sludge Generation Data from 1989 NCASI Survey Production Category
No. of Mills Reporting
Sludge Produced Mean
Median 8
lb/ADMTP -— Non-Integrated
25
48.5
34.5
Waste Paper
4
48.5
17.5
Deinking
8
380.0
390.0
Groundwood
10
52.0
40.5
Sulfite
10
85.5
62.5
Semi-chemical
7
23.0
13.5
Unbleached Kraft and Cross Recovery
21
24.5
18.5
Bleached Kraft
33
58.0
51.5
a
ADMTP - air-dry metric ton of pulp. Source: Adaptedfromréf. 1.
In Agricultural Uses of By-Products and Wastes; Rechcigl, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.
Downloaded by PENNSYLVANIA STATE UNIV on September 6, 2012 | http://pubs.acs.org Publication Date: July 1, 1997 | doi: 10.1021/bk-1997-0668.ch012
12. CAMBERATO ETAL.
Paper Manufacturing Residuals
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Paper manufacturing residuals have traditionally been landfilled but stringent regulations on the construction of new landfills has greatly increased the cost of disposal. Land application of these residuals to crop or forest lands represents a beneficial alternative to disposal. Based on their composition, mill residuals are classified as non-hazardous under the United States Environmental Protection Agency (USEPA) Resource Conservation and Recovery Act (RCRA). Under this Act, only nonhazardous materials can be land applied. Beneficial use through land application is based on their ability to favorably alter soil properties such as plant nutrient availability, soil reaction, or properties related to enhanced soil organic matter status such as cation exchange capacity, water holding capacity, tilth (physical condition of soil related to tillage, seedbed, and rooting media), and soil strength. This paper will review the composition and land application of wastewater sludges and causticizing residuals generated by paper manufacturing. Land application of wastewaterfromsludge treatment and boiler ashes are not discussed in this paper, but information on these topics can be obtainedfromother sources [wastewater-(2), boiler ashes (3-5)]. Waste Treatment Sludges Plant Nutrient, Metal, and Organic Content of Sludges. Essential plant nutrient concentrations for pulp and paper mill sludgesfromsurveys across the USA and typical nutrient levels for municipal sewage sludges are presented in Table ΠΙ. These data show that pulp and paper sludges vaiy substantially in plant nutrient composition and typically have lower levels of essential plant nutrients than municipal sewage sludges. Metal concentrations of paper manufacturing sludges and municipal sewage sludges are presented in Table IV. Median levels of As, Cd, Co, Hg, Pb, Sn, and Se are substantially lower in paper manufacturing sludges than in municipal sludges. Aluminum is perhaps the only metal that may be present in paper manufacturing sludges at higher levels than in municipal sludges. Thacker and Vriesman (6) report that the results of Extraction Procedure (EP) toxicity tests conducted by NCASI (14) and individual paper companies indicate that paper manufacturing sludges would rarely be classified as hazardous materials due to heavy metal content. The characterization data presented in Tables ΙΠ and IV pertains primarily to sludgesfromvirgin chemical pulping mills. Someshwar et al. (15) presented a detailed analysis of the composition of several deinking sludges, addressing chemical constituents and the results of EP toxicity and Toxicity Chemical Leaching Procedure (TCLP) characterizations. Their data showed that the composition of deinking sludges were comparable to thosefromchemical pulping operations and were also comparable or superior in quality to municipal sewage sludges. The EP toxicity and TCLP characterizations showed that all measured concentrations were less than 5% of hazardous waste thresholds. TCLP characterizations of sludgesfromvirgin pulping mills have also generally been found to be non-hazardous (e.g., Table V). Besides the TCLP analyses, only limited information on organic compounds in sludges is available. Only chloroform was found in detectable quantities (between 0.26 and 2.4 mg kg" dry weight-well below TCLP regulatory levels) in analyses of wastewater sludgesfroman integrated bleached Kraft/fine paper mill and an integrated 1
In Agricultural Uses of By-Products and Wastes; Rechcigl, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.
In Agricultural Uses of By-Products and Wastes; Rechcigl, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.
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1.37 29.5 0.65
0.37-6.0 2.7-90.2 0.11-1.0
8
a
8
—
5.11-28.2
0.15-2.65 13.0-148 0.72-5.07 0.1-10.5
0.19-2.57
3.0-15.5
—
13.5
0.96 60.0 2.30 4.1
1.2
8.76
—
4-1,000
0.2-650 1.0-250 0.3-25.0 6.0-15
