For several years, ODS-containing solvents have been used by maintenance organizations as degreasers for metal components. Due to current bans on these hazardous substances, ODS-free alternatives have been developed for cleaning/degreasing applications: 1) Aqueous, 2) Mechanical, 3) Semi-Aqueous, and 4) Petroleum Distillates (Aliphatic Hydrocarbons).

The most environmentally sound ODS alternative is aqueous cleaning. According to the Army Technical Bulletin on Environmentally Safe Substances for Use with Communications-Electronic Equipment, these are water-based systems that are used for soil removal. In this system, the designated area is wiped clean with a mild solution of detergent and water. The weakest detergent that will achieve the maximum results should be chosen. Following wiping, the area must be thoroughly rinsed with water (if possible warm-hot). For electronic equipment, a final rinse must be applied using distilled or de-ionized water. Finally, the components must be completely dry before use. The wastewater generated by this system, provided it meets the local discharge requirements through toxicity tests, may be discharged into the local sewer system. This cleaning application is used to remove both organic and inorganic soils, as well as light oils and residues left by other cleaning processes.

The second ODS-free alternative available is mechanical cleaning. This system utilizes equipment that uses a combination of hydroblasting and heat in order to remove organic and inorganic soils. This equipment also requires a detergent that may be recirculated throughout the system. For more information on this type of system, please refer to Pollution Prevention data sheet 8-II/A-1.

The third alternative that is currently in use is semi-aqueous degreasers. According to The Product Substitution Guide for the Oil Field Service Industry, this process combines water with various ODS-free solvents for heavy degreasing applications. This method, although not as environmentally sensible as aqueous cleaning due to the use of solvents, is more effective than the previous system in the removal of heavy organic soils. The contaminates resulting from this system must be removed and treated accordingly or a large waste stream could result if not recycled.

The fourth and final process used to replace ODS containing solvents are petroleum distillates (aliphatic hydrocarbons). These are non-chlorinated solvents which can be used for immersion tank cleaning and wiping applications. When this type of process is employed, the weakest strength solvent that will achieve maximum results should be chosen. This method is most suitable where rapid drying is required. Unfortunately, most of the alternative solvents dry at a much slower rate than the chlorinated ones. In addition, unlike their chlorinated counterparts these alternatives are not universal. Where one ODS containing solvent was required to clean various types of equipment in numerous applications, now a combination of replacement solvents must be employed in order to achieve similar results. Of the four available alternatives, this is the least beneficial to the environment. Although these solvents do not contain ozone-depleting substances, some have high volatile organic compound (VOC) content and may have a low flash point. The wastes generated from this system are still considered hazardous wastes and should be disposed of in accordance with local, state, and federal regulatory agencies.

• Does not deplete ozone layer.
• For non-mechanical systems:
  • Unused portions of product are biodegradable; and
  • Relatively low operative and capital costs.
• For non-petroleum distillate systems:
  • Low toxicity.
• For mechanical and aqueous systems:
  • Eliminates Volatile Organic Compounds (VOC);
  • Not flammable or combustible; and
  • Significant reduction in hazardous substances used.
• For semi-aqueous and petroleum distillate systems:
  • Relatively low amounts of waste produced.
• The semi-aqueous system works well in low temperatures.

• For the aqueous systems:
  • Possible costs increase in water and energy;
  • Possible increase in floor space; and
  • Possible increase in drying time for components due to low VOC content.
• For the mechanical systems:
  • Time consuming; and
  • Higher initial capital costs.
• For both the semi-aqueous and petroleum distillate systems:
  • Relatively low flash points (Possible flammable or combustible); and
  • Possible high VOC content.
• For the semi-aqueous systems:
  • Difficult recycling by distillation; and
  • Possible rinsing and drying required.
• For the petroleum distillate systems:
  • Slower drying time than TCE;
  • Possible exposure to benzene; and
  • Possible oily residue.

According to The Product Substitution Guide for the Oil Field Service Industry, the costs for purchasing, treatment, cleanup and disposal of hazardous chemicals would decrease using any of the alternatives. For example, since 1987 the costs for cleanups in Prudhoe Bay have been estimated at over $2.5 million. With the elimination of these hazardous materials, there would be no costs for cleanups. Another cost that would be eliminated is transportation of hazardous wastes. Using Prudhoe Bay as an example, the cost to transport one 55 gallon drum of hazardous waste could range from $500 to $1000. With the exception of petroleum distillates, the alternatives would greatly reduce this cost if not eliminate it altogether. Following is an example of an economic analysis of a mechanical system (aqueous jet parts washer) and a vapor degreaser (1,1,1 Trichloroethane).

Assumptions:

• Aqueous detergent consumption: 200 lbs.
• Aqueous detergent cost: $2/lb.
• Annual filter changeouts: 12
• Replacement filter cost: $10/filter
• Labor required for inspection of parts for aqueous system: 600 hrs./year
• Labor required for parts scrubbing, cleaning, and inspection using vapor degreasing: 800 hrs./year
• Maintenance labor equivalent for both systems.
• Labor rate: $30/hr.
• Aqueous system electricity consumption: 4,800 kw·hr.
• Vapor system electricity consumption: 9,500 kw·hr.
• Electricity rate: $0.08/kw·hr.
• Process water consumption: 5,500 gallons/year
• Process water purchase rate: $0.002/gallon
• Aqueous system sludge disposal cost: $700/year based on two 55-gallon drums
• Laboratory profile analysis of sludge: $1,000/yr.
• Sewer discharge cost: $8.24/1000 gallons
• TCA solvent procurement cost: $3,500/yr. based on 200 gallons/year consumption of TCA
• Solvent disposal: $1,700/year based on seven 55-gallon drums of spent solvent and soiled rags
• Solvent profile analysis: $2,500/year

Annual Operating Cost Comparison for Aqueous Jet Parts Washer and TCA Vapor Degreasing