United States Office of Air Quality EPA-453/R-93-025 Environmental Protection Planning and Standards June 1993 Agency Research Triangle Park NC 27711 Air EPA AIR EMISSIONS AND CONTROL TECHNOLOGY FOR LEATHER TANNING AND FINISHING OPERATIONS control technology center CTC EPA-453/R-93-025 AIR EMISSIONS AND CONTROL TECHNOLOGY FOR LEATHER TANNING AND FINISHING OPERATIONS CONTROL TECHNOLOGY CENTER SPONSORED BY: Emissions Standards Division Office of Air Quality Planning and Standards U. S. Environmental Protection Agency Research Triangle Park, North Carolina 2771 1 Air and Energy Engineering Research Laboratory Office of Research and Development U. S. Environmental Protection Agency Research Triangle Park, North Carolina 27711 June 1993 EPA-453/R-93425 June 1993 AIR EMISSIONS AND CONTROL TECHNOLOGY FOR LEATHER TANNING AND FINISHING OPERATIONS Prepared by: Barry F. Mitsch Reese H. Howle Samuel C. McClintock Alpha-Gamma Technologies, Inc. 900 Ridgefield Drive, Suite 350 Raleigh, North Carolina 27609 Under Subcontract to: Radian Corporation 3200 E. Chapel Hill Road/Nelson Highway Research Triangle Park, North Carolina 27709 EPA Contract No. 68-D1-0117 Work Assignment No. 79 Project Officer lliam Rosario Emission Standards Division U. S. Environmental Protection Agency Research Triangle Park, North Carolina 27711 Prepared for: Control Technology Center U. S. Environmental Protection Agency Research Triangle Park, North Carolina 27711 Acknowledgement This document was prepared for the EPA’s Control Technology Center (CTC) by Alpha-Gamma Technologies, Inc. under subcontract to Radian Corporation. The Alpha-Gamma project team included Barry F. Mitsch, Reese H. Howle, and Samuel C. McClintock. The EPA Work Assignment Manager was lliam Rosario. PREFACE The purpose of this document is to provide information to State and local agencies for use in assessing appropriate measures to control volatile organic compound (VOC) emissions from leather tanning and finishing facilities. Another objective of the report is to evaluate leather tanning and finishing processes and determine their potential to emit VOC’s and hazardous air pollutants (HAP’S) to the atmosphere. This document is the product of a study sponsored by EPA’s Control Technology Center (CTC). The CTC was established by EPA’s Office of Research and Development (ORD) and Office of Air Quality Planning and Standards (OAQPS) to provide technical assistance to State and local air pollution control agencies. Three levels of assistance are available through the CTC. First, the CTC maintains a hotline to provide telephone assistance on matters relating to air pollution control technology. Second, engineering assistance can be provided by the Center when appropriate. And finally, the CTC provides technical assistance through publication of technical assistance documents, development of personal computer software, and presentation of workshops on control technology subjects. This document represents the product of a CTC technical assistance effort. The CTC became interested in pursuing this project as a result of numerous calls from State and local agencies regarding control of VOC emission from leather tanning and finishing facilities. This document was developed using information obtained from available literature, information provided through Federal, State, and local air pollution control agencies, and information obtained from the leather tanning and finishing industry. TABLE OF CONTENTS Page 1.0 Introduction ............................................. 1-1 1.1 Objectives of the Report ................................. 1-2 1.2 Overview of the Report .................................. 1-2 2.0 Industry Description ....................................... 2-1 2.1 Characterization of the Industry ........ ..................... 2-4 2.2 References ........................................... 2-8 3.0 Leather Tanning and Finishing Processes ...................... 3-'1 3.1 Wet operations ....................................... 3-1 3.1.1 Soaking .................................... 3-3 3.1.2 Unhairing ................................... 3-3 3.1.3 Bating ..................................... 3-5 3.1.4 Pickling .................................... 3-5 3.1.5 Tanning .................................... 3-5 3.1.6 Trimming and Siding ........................... 3-7 3.1.7 Splitting .................................... 3-7 3.1.8 Retanning ................................... 3-9 3.1.9 Coloring .................................... 3-9 3.1.10 Fatliquoring ................................. 3-9 3.2 Dry Operations ....................................... 3-11 3.2.1 Drying .................................... 3-11 3.2.2 Conditioning ................................ 3-11 3.2.3 Staking and Milling ........................... 3-12 3.2.4 Buffing .................................... 3-12 3.3 Leather Finishing Operations ............................. 3-12 3.3.1 Coatings Used for Leather Finishing ............... 3-12 3.3.2 Application Methods for Leather Finishing ........... 3-19 3.3.2.1 Spray Systems .......................... 3-19 3.3.2.2 Roll Coating Machines ................... 3-24 3.3.2.3 Flow Coating Machines ................... 3-24 3.4 Additional Dry Operations ............................... 3-24 3.4 Waterproofing Operations .......... ..................... 3-28 3.5 References ........................................... 3-28 4.0 Characterization of Emissions ................................ 4-1 4.1 Sources of VOC and HAP Emissions ... 4-1 4.1.1 Leather Finishing'Operations .. .................. 4-1 4.1.2 . Waterproofing Operations .......... ............ 4-4 4.1.3 Solvent Degreasing ............................ 4-6 4.1.4 Miscellaneous Fugitive Emissions ................... 4-6 4.2 Factors Affecting VOC and HAP Emissions .................... 4-7 4.3 Volatile Organic Compound Emissions ....................... 4-9 4.4 Hazardous Air Pollutant Emissions .......................... 4-9 4.5 References .......................................... 4-15 LIST OF TABLES LIST OF FIGURES 1.0 INTRODUCTlON One of the major goals of the Clean Air Act Amendments of 1990 (CAAA) is to achieve compliance with the national ambient air quality standard for ozone. Title I of the amendments presents provisions for achieving the ozone standard. Among these provisions is a requirement that States adopt reasonably available control-technotogy (RACT) for major sources of VOC's. Under the amendments, a major source is defined as one with a potential to emit 100 tons or more of VOC's if that source is located in an area classified as marginal or moderate nonattainment for ozone. If the area is classified as serious nonattainment for ozone, the threshold for a major source is lowered to 50 tons per year. Further, the threshold for a major source is 25 tons per year in an area classified as severe nonattainment, and 10 tons per year in an area classified as extreme nonattainment. In addition, Section 184 of the CAAA creates the Northeast ozone transport region which includes 11 States in the Northeast corridor from Washington, DC, to Maine. In the transport region, a major source is one with a potential to emit 50 tons or more of VOC. Major sources in the transport region are subject to the same requirements as major sources in moderate nonattainment areas. The determination of RACT can be done on a case-by-case basis, but States typically adopt RACT as defined by Control Technique Guidelines (CTG's) issued by EPA. As of 1990, EPA had issued 29 CTG documents and was in the process of developing an additional 12 documents. The CAAA requires States to adopt RACT for both major sources in industries covered by CTG's, and for major sources in industries not covered by any existing CGT. These provisions of the CAAA have a potential impact on the leather tanning and finishing industry. Many leather tanning and finishing facilities may be reclassified as major sources under the stricter requirements of the Act. In addition, a large number of facilities are located in the Northeast transport region. The EPA has not issued a CTG for this industry and does not anticipate issuing a CTG document in the near future. Therefore, States are left with the burden of determining RACT for any major sources of VOC's in the leather tanning and finishing industry. 1-1 1.1 Objectives of the Report The CTC has received a number of calls from State and local agencies requesting guidance on controlling VOC’s from leather tanning and finishing facilities. One of the objectives of this report is to document existing emission control and reduction methods currently used in the industry. State and local agencies will use this information to help determine RACT for facilities in their jurisdiction. Another objective of the report is to identify and characterize the emissions of HAP’s from the industry. In Title III of the CAAA, Section 112(c) requires EPA to publish a list of categories of major and area sources for regulation that emit one or more of the HAP’s listed in the section. Presently, leather tanning and finishing plants are not on the list of major or area sources listed for regulation. The information contained in this report will be used to determine if leather tanning and finishing should be added to the list. 1.2 Overview of the Report The information contained in this document has been obtained from a variety of sources. Contacts were made with numerous State and local agencies that have leather tanning and finishing facilities located in their jurisdictions.