The EPA has recently proposed a revised schedule for issuing 6 Maximum Achievable Control Technology (MACT) National Emission Standards for Hazardous Air Pollutants (NESHAPs) of relevance to chemical and plastics manufacturers. The intent of these standards is to accelerate the use of advanced technologies to reduce the emissions of Hazardous Air Pollutants (HAP) and to thereby improve air quality. These standards have important consequences for some chemical manufacturing facilities. This article presents an overview of the new MACT standards.
Regulatory Background
Among the most ambitious requirements of the Clean Air Act Amendments of 1990 (CAA) are the Maximum Achievable Control Technology (MACT) standards being set for the reduction of emissions of Hazardous Air Pollutants (HAPs). HAPs, also known as toxic air pollutants or air toxics, are pollutants that (or may) cause cancer or other serious health effects such as reproductive problems, birth defects, or adverse environmental and ecological effects.
Although the U.S. Environmental Protection Agency (EPA) is required to set standards for 188 HAPs, standards have not yet been issued for most of these. The EPA must also occasionally review the list or revise it by rule. Six of the major source category groupings that apply to chemical manufacturing and distribution have currently proposed 10 year standards, which is the focus of this article. Effective dates are unclear for these standards. Proposed rules for a seventh category, Plastic Parts and Production (Surface Coating), were announced on December 4, 2002 but are not discussed here.
The MACT standards can require facility owners/operators to meet emission limits, install emission control technologies, monitor emissions and/or operating parameters, and use specified work practices. The EPA has been conducting analyses to support its technology requirements and was asked by Congress to promulgate the section 112(d) standards for 174 categories of major and area sources by November 15, 2000. All source categories are listed within section 112(c) of the CAAA. This list has been divided into three groups, or “bins” of MACT standards: the two-and four-year standards were required to be promulgated in 1994; seven-year standards in 1997; and ten-year standards in 2000.
The EPA sets MACT standards for both existing and new sources. Major stationary sources are defined as facilities that emits 10 or more tons of any one of the specified list of HAPs, or 25 tons per year (tpy) or greater of any combination of HAPs. MACT standards must not be less than the average emission level achieved by controls on the best performing 12% of existing sources, by category of industrial and utility sources. Thus, the MACT may be an "end of pipe" control technology or a pollution prevention-type process modification.
Determination of the MACT for each industry source category depends on the “MACT floor”. This is the minimum control level established through review of existing controls in a particular source category. The MACT floor ensures that the standard is set at a level of control at least as stringent as that already achieved by the better-controlled and lower-emitting sources in each source category or subcategory. For new sources, the MACT floor is the level of HAP emissions control currently achieved by the best-controlled similar source. In developing the MACT requirement, the EPA also considers control options and may establish standards more stringent than the floor based on cost considerations, public health and environmental impacts, and energy requirements.
The EPA has also identified 33 Urban Air Toxics, 30 of which emanate from small industrial operations. These generally are not major air pollution sources, such as chemical facilities that emit less than 10 tpy of a HAP. The plan is to require small emitters of listed urban air toxics to adopt the MACT, to be mandated by regulations. The EPA may develop MACT standards in rules that set maximum permissible emission levels for these Urban Air Toxic facilities by 2004.
A major concern to the EPA is how to estimate HAP emissions. A mass balance approach is not acceptable. Each facility must take a process-oriented view, analyze which of eight different emitting operations occur, collect process data, and use equations to estimate emissions from each process step.
MACT Hammer Day: May 15, 2002
When Congress amended the CAA in 1990 it included a mandate that MACT standards be adopted for many industrial facilities over the next 10 years. Further, Congress included a provision in section 112(j) that would mandate site-specific MACT standards if the EPA did not adopt industry-wide National Emission Standards for Hazardous Air Pollutants (NESHAPs) by May 15, 2002. Since establishing site-specific MACT standards for each major source of HAPs would be an immense burden for both industry and government regulators, this provision was called the "MACT hammer." Since the burden was thought to be great on all parties it was assumed that the EPA would be highly motivated to complete the MACT work within the anticipated schedule.
Unfortunately, the EPA missed the May 15 deadline for many source categories. Anticipating this eventuality the EPA issued a final rule on April 5, 2002 to extend until May 15, 2004 the deadline for companies to submit detailed applications for permits under which state air agencies would determine their HAP emission limits on a case-by-case basis. The promulgation delay by EPA forces industry and the state air agencies to make MACT determinations in absence of a specific rule, or based on proposed rules, rather than a final rule; thus the April 5, 2002 rule delayed the application of the hammer. If the MACT Hammer rule applies to your facility, you should thus evaluate its applicability on a case-by-case basis.
The EPA was sued over the April 5, 2002 rule, however, by the Sierra Club on April 25 in the Washington, D.C. Circuit Court. In a revised proposed settlement agreement filed on December 9, 2002, the EPA and the Sierra Club agreed to reduce the deadline extension by one year, or to May 15, 2003 (Sierra Club vs. EPA, D.C. Cir., No. 02-1135, 8/15/02). This deadline would apply only in the event that the EPA fails to meet its revised schedule for issuing the MACT standards. The Small Business Administration and the National Association of Manufacturers filed comments with the EPA on September 25, 2002 objecting to the settlement on cost grounds.
Newly Proposed/Final 10-Year MACT Standards
The six chemical source category groupings that are in the 10-year bin that originally had proposed MACT standard deadlines of May 15, 2002 are:
Mercury Cell Chlor-Alkali Plants
The EPA proposed a MACT standard rule for the chlor-alkali industry on July 3, 2002, which updates the mid 1970s NESHAP for mercury cell chlor-alkali plants. A final rule is due by October 30, 2003. These facilities are used to manufacture chlorine and caustic as co-products, and hydrogen as a by-product through the electrolytic decomposition of brine in mercury cells. Mercury recovery facilities are also covered. The proposed rule was published in the Federal Register. Section 63.8182 explains the applicability of the standard to various facilities. This proposal replaces one that was initially envisioned for the chlorine production industry more broadly.
Since mercury is a neurotoxin that is emitted to the air from a variety of sources (usually in the elemental or inorganic forms), transports through the atmosphere and eventually deposits onto the land or into water bodies, the human health effects of greatest concern are those on fetuses and infants. When deposited into surface waters, natural processes cam transform some of the mercury into methylmercury that accumulates in fish. The proposed MACT standard would limit mercury air emissions nationwide by about 9,100 pounds per year from the levels allowed by the existing mercury NESHAP for point and area sources. It would require significant reductions in emissions from point sources and significantly increased housekeeping, monitoring, and reporting requirements for the cell rooms. Specifically, a standard of 0.067 grams of total mercury emitted per megagram of chlorine produced is proposed for existing facilities with end-box ventilation systems, and half that level for existing facilities without end-box ventilation systems. For new or reconstructed chlor-alkali production facilities, the proposed rule prohibits mercury emissions.
Miscellaneous Organic Chemical Production and Processes NESHAP (MON)
and Miscellaneous Coating Manufacturing NESHAP
The MACT standard for MON covers batch processes including resin production, and formulation/blending operations, including paint, coatings, ink, and adhesives manufacturing. The MON source category includes many previously unregulated organic chemical processing units at major sources. The EPA issued proposed rules for this category on April 4, 2002. A final rule is due by October 30, 2003.
The proposed standard will require all major sources in the relevant source categories to meet HAP emission limitations and work practice standards reflecting the application of the MACT. The annualized cost of the MON rule would be $78 million, and $16 million for the Miscellaneous Coating Manufacturing rule. The proposed rules would reduce air toxics emissions by about 31,000 tpy from MON facilities and 6,000 tpy from miscellaneous coating manufacturing facilities. The proposed rules would also reduce volatile organic compound (VOC) emissions, which contribute to ground-level ozone (O3) formation.
The proposed action also includes provisions that allow industry to comply through an alternative, pollution prevention-based standard. The alternative standard requires significant reductions in the amounts of toxic air pollutants used during the manufacturing process. The rule would allow facilities to focus on improving processes by reducing solvent use.
Air toxics are emitted during the production of organic chemicals and coatings, such as paints, inks, and adhesives. Air toxics released from these industries include toluene, xylene, methylene chloride, methanol, and hydrogen chloride. Methylene chloride is considered to be a probable human carcinogen and the other pollutants can cause noncancer health effects in humans. The MON production source category has been created to include 23 listed source categories, primarily from the chemical process and the polymers and resins industry groups. The 23 source categories covered under MON are shown in Table 1.
| Table 1. Source Categories Covered Under the Proposed MON Rule |
|
Alkyd Resins Production |
The MON rule will affect some chemical processes that haven’t been previously covered by the NESHAP program. The proposed rules require excellent air emission MACT controls for potential emission reductions at process vents, storage tanks, equipment leaks, wastewater systems, and transfer operations at organic chemical and coating manufacturers. As with other MACT standards, those in the MON rule will affect major sources of HAP. Existing product processes with potential emissions below 1000 lb./yr of HAPs would be exempt from the MON rule. For new processes, this would be 3000 lb/yr of HAPs. Table 2 provides a summary of the MACT floor determinations for batch and continuous chemical processes at existing sources.
| Table 2. MACT Floor Determinations for Chemical Processes at Existing Sources | |||
|
Source Type |
Required Control |
Performance Level |
|
|
Process vents |
98% reduction |
Each continuous with a vent within a facility with a TRE ≤ 2.8 |
All batch vents within a product process with total product process HAP emissions ≥ 10,000 lb/year |
|
Storage tanks |
IFR/EFR or 95% reduction |
Tank with capacity ≥ 10,000 gal and HAP partial pressure ≥ 1.0 psia |
|
|
Wastewater |
same reductions as required by the HON |
wastewater streams with total VOHAP concentration
≥ 10,000 ppmw, |
|
|
Equipment components |
HON equivalent LDAR program |
All affected product processes |
|
The MON rule is being developed concurrently with the organic liquid distribution (OLD) NESHAP (see below), and potentially will regulate certain OLD sources (i.e., storage tanks, transfer racks, and equipment leaks) located at MON facility plant sites that will be required to meet the MON NESHAP rather than the OLD NESHAP. Thus, two of the most common approaches for preventing pollution (product reformulation or substituting less polluting products) are not available to these facilities. Similarly, these facilities cannot use recycling or reuse as a way of limiting the amount of these liquids.
The proposed equipment and work practice standards, however, would prevent pollution from two of the principal emission sources in OLD operations. For storage tanks, the EPA expects floating roofs to be used as a common alternative to add-on control technologies. For leaks from equipment such as pumps or valves, the required leak detection and repair program (LDAR) also would prevent pollution at the source without the need for add-on control equipment.
Organic Liquids Distribution (Non-Gasoline)
Several organic liquid chemicals, such as benzene, ethylbenzene, toluene, vinyl chloride, and xylenes, have been classified by the EPA as Group A human carcinogens. An OLD (non-gasoline) operation is the combination of activities and equipment used to transfer organic liquids into or out of a plant site or to store organic liquids on the plant site, which are carried out at storage terminals, refineries, crude oil pipeline stations, and various manufacturing facilities. Such operations take place at liquid terminal facilities, organic chemical manufacturing facilities, petroleum refineries, crude oil pipeline pumping and breakout stations, and other industrial facilities that have an organic liquid distribution operation. The EPA estimates that approximately 77,300 tpy of HAPs are emitted from facilities in this source category. Table 3 shows SIC/NAICS Codes for OLD entities regulated by this MACT requirement.
| Table 3. SIC/NAICS Codes for Organic Liquid Distribution entities regulated by MACT | |||
|
Category |
SIC |
NAICS |
Examples of Regulated Entities |
Industry |
2821 |
325211 |
Operations at major sources that transfer organic liquids into or out of the plant site, including: liquid storage terminals, crude oil pipeline stations, petroleum refineries, chemical manufacturing facilities, and other manufacturing facilities with collocated OLD operations. |
Federal Government |
N/A |
N/A |
Federal agency facilities that operate any of the types of entities listed under the ``industry'' category in this table. |
The EPA proposed a rule for this source category on April 2, 2002. A final rule is due by October 30, 2003. The proposed standards would result in the reduction of HAPs emissions from major sources in the OLD source category by about 28%. OLD plant sites that are potentially subject to the proposed MACT standards may also be subject to other NESHAP because of other activities that take place on the same plant site. For instance, some tank farms are used to store and transfer organic liquids onto or off a synthetic organic chemical manufacturing industry (SOCMI) plant site.
An OLD operation is subject to this proposed rule if it meets both of these criteria:
(1) The facility is at or is part of a major source of HAP emissions, and
(2) It has a total organic liquids throughput of 27.6 million liters (7.29 million gallons) per year or more either into or out of the operation.
How can OLD facilities meet these criteria and improve their environmental effects? The most important point is that the proposed rule requires the installation of strict emission controls at three emission points: storage tanks; transfer racks; and equipment leaks. The equipment used for the distribution of organic liquids and the control of emissions from that equipment is the same throughout the facilities included in the source category. By requiring use of advanced technologies, this rule encourages pollution prevention:
- Storage tanks would be required to control emissions by using a floating roof cover or a fixed roof cover and venting to a control device,
- Transfer racks -- Control would be required for racks that load 3.12 million gallons of liquids with an air toxics content of 5% or greater, and
- Equipment leak provisions will affect equipment that contains or has contact with an organic liquid that has air toxics content of 5% or greater for at least 300 hours a month. For such equipment, a LDAR program using an organic vapor detection instrument is required.
Hydrochloric Acid Production
Hydrochloric acid (HCl) is used in a variety of industrial processes including: refining ore for the production of tin and tantalum, pickling and cleaning of metal products, electroplating, cleaning boilers, neutralizing chemically basic systems, manufacturing fertilizers, dyes, textiles and rubber, and preparing various food products. HCl is also used as a laboratory reagent. An HCl production facility involves the collection of equipment used to produce, store, and transfer liquid HCl product for shipping at a concentration of 10% by weight or greater. Exposure to HCl and chlorine may produce a wide variety of human adverse health chronic and acute disorders including irritation of the lungs, skin, and mucous membranes; dysfunction of the central nervous system; digestive and respiratory problems; and skin irritation. The EPA proposed a rule for this category on September 18, 2001. A final rule is due by May 15, 2003. It is estimated that this proposed NESHAP would reduce nationwide emissions of HAP from HCl production by approximately 1,790 tpy.
This MACT covers both the HCl production source category and the fume silica source category. Facilities that produce, store, and transfer for shipping liquid HCl at concentrations of 10% by weight or more that are located at major HAP sources will be subject to newly proposed MACT standards. Meanwhile, regulated facilities also would be subject to the usual range of other MACT standard requirements, many of which would be incorporated by reference from the general NESHAP provisions. Most HCl production sources to be regulated by this proposal make HCl as a by-product. Any process that routes a gaseous stream containing HCl to an absorber and creates a liquid containing at least 10% by weight of HCl could potentially be regulated under this proposal. The combined source category (named HCl Production) is comprised of about 64 facilities in the U.S. This number represents the best information the EPA has as of this time; it should not be considered to be definitive as it is probably incomplete but it is considered representative.
This MACT is applicable to owners/operators of HCl production facilities that are located at or are part of a major source of HAP, except for the operations listed below. Operations not subject to this MACT include:
(1) Operations that produce liquid HCl are subject to one of the NESHAP listed below -
- NESHAP from the Pulp and Paper Industry;
- NESHAP for Steel Pickling--HCl Process Facilities and HCl Regeneration Plants;
- NESHAP for Pesticide Active Ingredient Production; and
- NESHAP for Hazardous Waste Combustors
(2) Operations that produce liquid HCl following the incineration of chlorinated waste gas streams and that are subject to the one of the requirements listed below -
- National Emission Standards for Organic HAPs from the SOCMI Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater;
- Incinerators: Standards for Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal Facilities; and
- Burning of Hazardous Waste in Boilers and Industrial Furnaces
(3) Operations where all of the HCl and chlorine (Cl2) vent streams from the equipment (including absorbers, storage tanks and transfer operations) at the HCl production facility are recycled or routed to another process prior to being discharged to the atmosphere.
Finally, any source that routes all of its HCl and Cl2 absorber, storage tank, and transfer operation vents back to the generating process or to another process rather than discharging them to the atmosphere is also exempt from the proposed HAP control standards.
The proposed MACT standards for this source category would implement the emission limits listed in Table 4. Besides the emission limits, sources would prepare and implement an LDAR plan to control fugitive emissions from equipment in HCl and Cl2 service. Although the proposed rule is short on details for such programs, the plans to be implemented must "detect leaks and repair them in a timely fashion." LDAR plans would be subject to the approval of the EPA.
|
Table 4. Proposed MACT Standards for the HCI Production Emission Limits |
|
|
Stream |
Emission limit |
|
HCl process vents |
12 ppmv HCl, or 20 ppmv Cl2 |
|
HCl storage tanks |
12 ppmv HCl |
|
HCL transfer operations |
12 ppmv HCl |
Flexible Polyurethane Foam Fabrication Operations
The EPA proposed a rule on August 8, 2001 to reduce emissions of toxic air pollutants from flexible polyurethane foam fabrication operations (a 7-Year Standard already exists). The final rule is due by May 15, 2003. This source category includes operations engaged in cutting, gluing, and/or laminating pieces of flexible polyurethane foam, including fabrication operations that are located at foam production plants, as well as those that are located off-site.
The proposal rule focused on reducing air toxics emitted from two foam fabrication emission sources. It enforced an existing industry trend to use:
1) non-air toxic based adhesives in loop slitter applications, which includes processes that use adhesives to bond foam to foam or to other substrates and then cut the foam using a loop slitter; and
2) controls on flame lamination equipment to reduce their hydrochloric acid (HCl) and hydrogen cyanide (HCN) air emissions by at least 90%. For instance, a typical new or reconstructed flame lamination operation would reduce its air toxic emissions by 6.5 tpy as a result of the proposed rule.
The EPA estimates no capital costs for facilities that use loop slitters and existing facilities using flame laminations to comply with the proposed rule. However, the proposed rule does not require existing major sources to use the flame lamination process -- it only requires that they submit an initial notification to the EPA to identify themselves. New or reconstructed facilities that use flame laminators would incur capital costs to purchase and install air pollution control devices (e.g., scrubber) and monitoring equipment. The EPA estimates this cost to be approximately $65,000 (per facility), for an annualized capital cost of approximately $9,300. Since the cost of control is a very small portion of industry revenues, the economic impacts associated with this rule are minor.
Reinforced Plastic Composites Production
The Reinforced Plastic Composites Production source category involves the production of plastic products from cross-linking resins, usually in combination with reinforcing materials and inorganic fillers. The production of products that do not contain reinforcing materials is also included in this category, as well as the production of intermediate compounds that are later used to make the final plastic products. These non-reinforced products were included because they are produced using the same types of resins, have similar emission characteristics and would use similar emission controls. Reinforced plastic composites production facilities emit HAPs, such as styrene, methyl methacrylate (MMA), and methylene chloride (dichloromethane). These HAPs have adverse health effects including headache, fatigue, depression, and irritation of skin, eyes and mucous membranes. Methylene chloride has been classified as a probable human carcinogen.
Final MACT decisions, however, have not yet been made for this source category. The EPA proposed a rule for this source category on August 2, 2001. A final rule is due by May 15, 2003. The proposed standards would regulate production and ancillary processes used to manufacture products with thermoset resins and gel coats. The EPA estimate that this proposed NESHAP would reduce nationwide emissions of HAP from these facilities by 65% or about 14,500 tpy.
The main pollutant of concern in this source category is styrene, which accounts for 90% of HAP emissions. The regulated industry believes that they can achieve substantial emission reduction through the use of best operating practices and are resisting the use of add-on control technologies for HAP control. This NESHAP will regulate approximately 488 production lines. The actual number of facilities covered by this rule will be significantly less than 488 due to co-location of different types of production lines at one site.
This source category currently contains 12 subcategories: open molding, pultrusion, gel coating, continuous lamination, filament winding, injection molding, compression molding, resin transfer molding, compounding (2), polymer casting, and centrifugal casting.
The proposed NESHAP provided several options for industry to comply with the MACT, thus providing industry the flexibility to decide which method is best suited for each subcategory:
- Open molding and centrifugal casting operations - This proposal would allow plants to choose to comply by meeting the individual MACT point value for each operation at the affected source, or by meeting the weighted average MACT point value for all open molding operations at the affected source. For open molding and centrifugal casting operations where the proposed rule would require the plant to meet a percentage reduction, the plant could use an add-on control device to achieve the required reduction or choose to meet a MACT point value that corresponds to that particular operation's percentage reduction.
- Continuous casting/lamination operations - The plant could demonstrate that each continuous casting line and each continuous lamination line meets the appropriate standard. Alternatively, the plant could average all the continuous casting and continuous lamination lines together, and demonstrate that they meet the appropriate standard. An additional alternative would be to capture the emissions from a plant's wet-out area in a permanent total enclosure that meets EPA's criteria, as specified in Method 204 in appendix M of 40 CFR part 51, and vent these wet-out emissions through a closed vent system to a control device achieving 95 % reduction of HAP emissions. Under this proposed rule, these alternatives could be used in combination to demonstrate compliance.
- Pultrusion operations - The plant could capture and vent the emissions to a control device that achieves the required percent reduction of HAP emissions. The plant could also elect to use direct die injection pultrusion machines with resin drip collection systems that meet the criteria specified. The rule also proposed an additional alternative only available to existing sources: the use of a wet-area enclosure with a resin drip collection system. For both new and existing sources, the plants could use the available options in combination to achieve compliance under this proposed rule.
- Ancillary Operations - For ancillary operations at all sources, such as cleaning, storage, and mixing/BMC operations at existing sources, the only option under this proposed rule is to comply with the specified work practice standards.
Summary
The EPA is issuing MACT standards to accelerate the use of advanced technologies to reduce HAP emissions from the chemical industry (among other) and to thereby improve air quality. Individual industrial facilities will investigate, develop, and assemble technical information on the performance, emissions, and economics of existing and emerging technologies that could be applied to meet the current and future MACT requirements. The basic steps involved are:
- Source Category Selection and Prioritization;
- MACT Rule Development Status;
- Technology Database Development and Population; and
- MACT Compliance Strategy Development.
We hope that this article has streamlined this process for the five reviewed source category groupings for small chemical manufacturing and distribution facilities in particular.
About the Authors
Barry Solomon serves as Associate Director of ChemAlliance, and is responsible for editorial content to the site, particularly in the area of environmental regulations. In addition to his role as Associate Director, Barry is an associate professor of environmental policy at Michigan Technological University. He has an MPA and PhD in Public & Environmental Affairs from Indiana University, and a B.A. in Social Ecology from University of California at Irvine. He has worked in the fields of environmental and energy policy for 20 years, including over 10 years at the U.S. EPA and U.S. DOE, and has authored or co-authored over 90 papers, reviews and reports and three books. He is currently the President-Elect of the U.S. Society for Ecological Economics.
Ying Han is a masters degree candidate in Environmental Policy, Department of Social Sciences, at Michigan Technological University. After graduating from the Tianjin Institute of Finance in China with a B.A. in 1997, she worked with the Hyundai Group, a global trading company, for three years. Her masters thesis is on the factors determining the development and marketing of "green" automobiles in the U.S.
