Pollution Prevention in Substituting Alternative Technologies for OzoneeDepleting Solvents

By Fanan A. Riza and Michael iV Zatz

The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer restricted the production and consumption of the most widely used industrial solvent -- CFC-113. In 1990, the London Amendments to the Montreal Protocol tightened restrictions on CFC-113 while intro- ducing new restrictions on methyl chloroform (MCF), another widely used solvent. At the present time, developed country Parties to the Montreal Protocol (including the U.S.) are mandated to phase out their use of CFC-113 and MCF by the year 2000 and 2005, respectively.

In response to these restrictions, the solvent-using industries have developed numerous alternative

chemicals and processes to take the place of CFC-113 and MCF. CFC- 113 and MCF have been widely used for solvent cleaning in the electronics, metal, and precision cleaning industries, as well as in- dustrial solvents in dry cleaning, ad- hesives, and aerosol applications. In phasing out the use of these sub- stances, companies can take a pollu- tion prevention approach which consists of six distinct elements:

Top management commitment. Characterize company-wide sol-

Establish conservation programs. Characterize existing cleaning

0 Evaluate process alternatives.

vent use and losses.

processes.

Implement alternative processes. The use of this type of pollution

prevention approach will ensure that a company executes its phaseout of ozone-depleting sub- stances (ODSs) in an efficient and economical manner.

Top Management Commitment

The first element in a pollution prevention approach is the estab- lishment of a strong management commitment. A primary component of this commitment is the develop- ment of corporate policy concerning ODSs at the highest level. This method of policy making will serve several purposes. First, it

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26 Environmental Waste Management Magazine/March-April 1992

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demonstrates a total company com- mitment to the phaseout of ODSs, from the top executive to the staff in the factory. Second, it allows the company to increase environmental awareness among employees and the public. Finally, it ensures that realistic targets will be established on which a phaseout schedule can be based.

Characterize Company-Wide Solvent Use and Losses

After a top management commit- ment to the phaseout of ODSs in solvent applications has been estab- lished, the company should charac- terize company-wide solvent use by conducting a material balance to compare the total solvent quantity purchased versus where in the manufacturing process this solvent is used and lost. Solvent losses in cleaning operations often occur in degreasing equipment (through dragout, evaporation, and downtime losses), holding tanks (through evaporation and leakage), and during transportation of solvent and/or solvent-cleaned parts from one process area to another. This

charactellzation of- solvent use and losses will enable the company to cut emissions and solvent purchases by identifying manufacturing pro- cesses which are in need of mod- ification.

Establish Conservation Programs

The third element of the pollution prevention approach is the estab- lishment of a solvent conservation program. While the best way to eliminate the consumption and use of ODSs in solvent applications is to discontinue their use, significant reductions in consumption and emissions (in some cases as high as 85 percent) can be obtained by in- stituting a comprehensive solvent conservation program. Such a pro- gram would consist of two types of actions. First, improved operating practices would be used. To increase the efficiency of operations, a com- pany would conduct additional operator training courses aimed at increasing operator awareness and knowledge. Other operating prac- tices which could be implemented to conserve solvent include: preven-

tion of drafts around equipment, the use of solvent log books, minimiza- tion of dragout losses, and frequeni maintenance and inspection oj equipment. Second, engineering controls can be used to conserve sol- vents. One example of such a con- trol is an increase in the freeboard height in a vapor degreaser. The freeboard height is defined as the distance from the solvent vapor/aiI interface to the top of the degreasing tank Increasing this distance will greatly reduce the amount of solvent emissions due to diffusion. Conser- vation programs which include these components will streamline operating procedures and should result in a substantial decrease in solvent emissions and consumption.

Characterize Existing Cleaning Processes

Characterization of existing clean- ing processes is the fourth com- ponent of a pollution prevention ap- proach. The ultimate goal of this step is to determine the feasibility of limiting or eliminating solvent cleaning operations. To determine if solvent cleaning is necessary, one

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Environmental Waste Management Magazine/March-April 1992 21

should first determine the nature of the contaminants which are removed in the cleaning process, as well as the origins of these con- taminants. In addition, an inventory of all parts cleaned, including their size, geometry, and material com- position will aid in the analysis of existing and future cleaning proces- ses. After all of this information has been gathered, an evaluation of the necessity of solvent cleaning can be made. Options which are available to reduce solvent cleaning needs in- clude reducing or eliminating the contamination of parts during the manufacturing process by minimiz- ing the number of times a part is soiled, consolidating the type of soils by reducing the number of process- indmachining fluids, and segrega- tion and precleaning of parts there- by extending life of cleaning agents and making cleaning more efficient.

Evaluate Process Alternatives

The fifth element in the pollution prevention approach is the evalua- tion of process alternatives. This is likely to be the step which requires the most effort and involves con- ducting technical, environmental, and economic feasibility analyses for a variety of alternative chemicals and processes. The selection of an alternative chemical or process in- volves numerous factors which must be evaluated together to determine which alternative provides the most desirable combination of technical, economic, and environmental at- tributes.

Technical considerations are those qualities of a chemical or process which determine the effec- tiveness of the alternative as a re- placement. One example of a tech- nical consideration is defect rate. This is a w r e of t h a m d x z d parts which do not meet minimum quality specifications after cleaning with the alternative method. Ideally, an alternative cleaning method should result in zero defects. How- Zver, some facilities may only re- quire that the defect rate be lower than their current cleaning process to consider the alternative method technically acceptable with regard to defect rate. Other technical con- siderations for evaluating chemical and process alternatives to ozone-

depleting solvents include the fol- lowing: 0 Compliance with specifications: 0 Materials compatibility; 0 Effect of level of cleanliness on

subsequent processes: 0 Process control: 0 Throughput: 0 Ease of installation: 0 Floor space requirements: and 0 Operating and maintenance re-

An evaluation of these considera- tions, as well as any others which company management deems relevant, will ensure that an alterna- tive is technically feasible.

quirements.

Economic considerations are an obvious concern in most industrial settings. An analysis of initial costs associated with an alternative clean- ing method should include capital costs of equipment (including instal- lation and waste treatmenuhandling needs) as well as the costs of addi- tional permits which might be re- quired. Projections of operating costs are equally important and should include material, labor, maintenance, and utility costs (in- cluding energy and water). In this case, the effect of limited supplies of ozone-depleting solvents will have a significant effect on the economic analysis. The high price of solvents ~-fiEly to accompany-€&F limited supply, coupled with in- creasing excise taxes on these sol- vents, should make most alternative chemicals and processes more at- tractive.

The environmental, human health, and safety effects of potential ODS substitutes must also be care- fully evaluated in determining the most desirable alternative. CFC-113 and MCF use is being eliminated due to concerns over their effect on

Environmental

the stratospheric ozone layer, but one does not want to trade one en- vironmental problem for another. Since new environmental policy is emphasizing pollution prevention and risk reduction, it is prudent to move to cleaner products and processes that are less polluting, less energy intensive, and less dependant on raw materials. In addition, recent legislation, such as "right-to-know" laws, has provided the public with more information about chemicals used by specific plants and their as- sociated risks. Public information has made plants more accountable to the concerns of neighboring com- munities.

Each alternative has differing ef- fects on water, air, and land pollu- tion. In many areas, switching sol- vents can take you from an existing to a newlmodified source, subject to repermitting and more stringent controls. Limitations on VOC emis- sions may influence your choice of alternatives. To move fonvard, alter- natives should offer similar or better environmental, health, and safety properties than CFC-113 and MCF.

The U.S. Environmental Protec- tion Agency (EPA) is currently con- ducting a risk characterization for potential substitutes under Section 612 (Safe Alternatives Policy) of the Clean Air Act of 1990. This evalua- tion will involve a comprehensive analysis based on ODSs, flam- mability, toxicity, exposure effects, energy efficiency, degradation im- pacts, air, water, solidlhazardous waste pollution effects, environmen- tal releases, and global warming potential.

There are currently a large num- ber of alternative chemicals and processes available to replace ozone-depleting solvent use in the electronics, metal, and precision

universally-accepted processes are aqueous and semi-aqueous clean- ing. In aqueous cleaning, water with saponifier and surfactants is used in place of a solvent to clean a part. The process consists of four steps: wash, rinse, dry, and waste disposal. Waste disposal of contaminated water can be accomplished via recy- cling in a closed loop system. This way, the water is used many times in the cleaning process before it be- comes too highly contaminated and

e 4 e a i m g - i ~ . &&e--

e Management Magazine/March-April 1992

is released to a wastewater treatment facility for final disposal. The semi- aqueous process is similar to the aqueous process. Instead of using water with detergent in the wash stage, a blend of hydrocarbon/sur- factants is used. The remaining steps @e., rinse, dry, and waste dis- posal) are similar to aqueous processes. Again, a closed loop sys- tem can be used to minimize water treatment needs. Other altematives which are currently used in the place of CFC-113 and MCF solvent cleaning include ”no-clean” tech- nologies, the use of other chlorinated solvents, and the use of organic solvents. Hydrochloro- fluorocarbons (HCFCs) due to con- cerns about higher ODSs and toxicity will have limited use.

Implement Alternative Processes

After a thorough evaluation of all the potential alternatives has been completed, a company which has concluded that a cleaning process is necessary should begin implementa- tion of its most desirable alternative. The implementation of the selected alternative should be coupled with the introduction of conservation and recovery practices, if applicable. In addition, the implementation period is an excellent time in which to con- duct training workshops which focus on the new technology, as well as retraining workers on the basics of efficient operation.

By following the pollution preven- tion approach detailed in this ar- ticle, a solvent-using company will ensure that its phaseout of CFC-113 and MCF will be both efficient and economical. In fact, the process itself

benefit a wmpauy in “e- ways than just the identification of an acceptable alternative cleaning :hemica1 or process. Through demonstrating a top management ”itment, the company will show to its employees and to the ?ublic that it is serious about protecting the environment while maintaining product quality. The :haracterization of solvent use and .osses will allow the company to .den@ points in the manufacturing ?recess at which changes or

Znvironmental Waste Management Magazir

modifications are needed. The im- plementation of conservation programs will not only reduce sol- vent use and emissions, but will also reduce costs. A characterization of its existing cleaning processes may lead a company to the realization that they can consolidate cleaning operations, if not eliminate them completely. The evaluation of a wide variety of potential chemical and process altematives will result in selecting the alternative which best suits their specialized situation, and will have the added benefit that

the company’s technical staff wiU have an extensive knowledge of the latest in non-ODS technologies. Finally, the implementation of the right alternative cleaning method will help to streamline operations, increase productivity, reduce en- vironmental pollution, and most im- portantly, protect the stratospheric ozone layer.

Fanan A. Riza is a SeniorAssociate and Michael N Zatz an Analyst at ICF Incoporated, in Washington, DC

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March-April 1992 29

Standardization of L

to Landfill

as (LFG) Emission Regulations b y US. Prove Costly

By Richkrd D./abro& P.E. I 1

In response to growing concern over landfill gas (LFG) emissions, the United States Environmental Protec- tion Agency (U.S. EPA) published its first proposed regulations governing LFG management in May 1991. After promulgation, expected in 1992, states will have nine months to submit Dlans for meetinq the new regulations.

U.S. EPAs biggest challenge lies in developing regulations that are site-specific, since many variables including refuse age, moisture co& tent within the landfill and geographi- cal climate, affect LFG generation. Unfortunately, U.S. EPA currently proposes to use a mathematical model to estimate LFG emissions, which does not take site-specific characteristics into account.

30

testing parameters when better surrogate parameters exist. The proposed rule regulates non- methane organic compounds (NMOCs), which require expen-

Environmental W

sive laboratory analysis to quan- tify. Testing for total organic car- bons (TOCs) is a more reliable indicator of LFG emissions. In ad- dition, TOCs can be measured in- expensively with field instruments. The proposed rule includes technically flawed methods for designing LEG collection s ~ : tems. The mathematical model specified by U.S. EPA will result in oversized LFG collection systems on small landfills. As currently stated, the regulation is only ap- plicable to large landfills with cer- tain design characteristics.

0 The criteria for LFG collection systems, as specified in the proposed regulation, are inap- propriate for designing and operating a system economi- cally. For example, the proposed

e Management Magazine/March-April 1992