The main difference between a conventional washing machine and an ozone washing machine is the addition of a pump/piping loop. Water from the washer drum is circulated through this loop. A venturi is used to inject the gaseous ozone. The ozone is generated in a three-step process; first air is compressed in an air compressor; next the resulting compressed air is passed through a pressure swing adsorption oxygen generator; and finally the oxygen is fed to corona discharge ozone generators.

The addition of gaseous ozone to the wash and rinse cycle offers several benefits to a laundry facility. Ozone is a strong chemical oxidant that treats the resulting wastewater such that the oil and grease are much less likely to redeposit on the fabrics. This allows for the quantity of rinse water to be significantly reduced. Since the ozone breaks down the organic contaminants, the resulting wastewater is much cleaner than that from a conventional industrial laundry. For most cases, the system wastewater may be directly discharged to a domestic sewer system without pretreatment. The addition of ozone also complements the cleaning chemicals so that less chemicals are required. This improved cleaning action is accomplished using cold water since the solubility of gaseous ozone in water is reduced as the water temperature increases.

The Ozone Laundry System is designed for simple operation and minimal maintenance. Once the wash program is set, system operation basically involves just turning the machine on to initiate the preset washing program. Cleaning chemicals are automatically injected into the washing machine. Like any industrial laundry, this system requires the handling of significant quantities of fabrics. A full-time dedicated operator is recommended. Operator-performed maintenance basically consists of periodically cleaning the filter baskets. A more extensive preventive maintenance program is also required.

The use of the ozone laundry system in place of rag disposal will decrease the amount of solid and/or hazardous waste generated. This helps facilities to meet the requirements of waste reduction under RCRA, 40 CFR 262; the Pollution Prevention Act (42 USC 13101-13109); and Executive Order (EO) 13148, Greening the Government Through Leadership in Environmental Management; and may also help facilities reduce their generator status and lessen the amount of regulations (i.e., recordkeeping, reporting, inspections, transportation, accumulation time, emergency prevention and preparedness, emergency response) they are required to comply with under RCRA, 40 CFR 262. In addition, the recycling of the contaminated rags will help facilities to comply with EO 13101, Greening the Government Through Waste Prevention, Recycling, and Federal Acquisition.

The compliance benefits listed here are only meant to be used as general guidelines and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g., the amount of workload involved.

Consult your local industrial health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing any wipe rag laundering program.

• Total costs are reduced by recycling wipe rags.
• Quantity of rags disposed of is significantly reduced.

For activities that are conventionally washing wipe rags:

• Total laundering costs are reduced.
• Water use is reduced.
• Cleaning chemical use is reduced.
• Hot-water use is eliminated.
• The chemical oxygen demand of the resulting wastewater is reduced approximately 71%.
• Washing cycle time is reduced.
• Laundered rags are cleaner.

• A significant capital investment is required. A system sized to annually clean 150,000 lbs. of wipe rags will cost approximately $75,000.
• The system uses patented equipment with only one supplier. In addition, the technology is relatively new and therefore long-term performance data are not available.
• To obtain maximum benefit from the system, a full-time operator is required.

To assess the systems economic advantage or disadvantage relative to the competing options, the attached spreadsheet program is provided. To use the program, enter the requested information on quantity of rags to be laundered, labor and utility costs, commercial rag cleaning service costs and rag disposal costs. The program will calculate the cost per pound of cleaned rags for the three options and the payback period for using the Ozone Laundry System. These results can then be used to justify a more detailed site-specific analysis. In general, the economics of the Ozone Laundry System are very favorable when the activity experiences a high rag loss rate, provides service for naval ships or when the activity disposes of rags at a high disposal cost.

Assumptions

• The laundry equipment ( i.e., washer, dryer & ozone machine) has a service life of 15 years.
• The interest rate used in the calculations is 8%.
• The costs are calculated for a rag loss rate of 10%.
• The price of baled rags is $0.40/lb. This is the current price under NSN 7920-00-205-1711.
• All of the cost for operating labor is included in the washing costs.
• The initial costs for baled rags is based on obtaining a 3-month supply.
• The dryer cost is based on a 45-minute drying cycle and a 3-minute cooldown cycle.
• The dryer utility costs were calculated based on their rated 370,000 BTU/hr gas supply and their two 1.5 Hp motors.
• The annual maintenance cost is assumed to be 2% of the equipment purchase and installation cost.
• Non-labor rag collection costs are assumed to be $100 per month.
• The cost per lost rag assumes that charges are only made for losses that exceed 10%.

• When ships are located out at sea and unable to access contractor rag cleaning services.
• When there are large discrepancies from one month to the next in the number of rags used/needed to be cleaned.
• When the facility is located in a remote location and unable to access contractor rag cleaning services.
• When it is difficult for the end user to keep track of the used rags. Contractors often issue a specific number of rags to a site per month. If rag loss rates are high (>20%), the site may have to determine the administrative costs associated with keeping track of the used rags and compare those costs with the lost rags fees imposed by the contractor.