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Three common P2 approaches are
New Technology (Equipment Upgrades)
In general, the process steps for wet cleaning are the same and are represented in the process map for dry cleaning (Figure A). Wet cleaning, like dry cleaning consists of four major steps including preparation, washing, drying, and finishing; however, a wet cleaning machine only washes the clothing. Clothing must then be transferred to a separate dryer (like older “transfer” dry cleaning machines). A detailed process map for wet cleaning was developed by Massachusetts Toxic Use Reduction and is available in their Training Curriculum for Alternative Clothes Cleaning. For further description and flow diagrams of the wet cleaning process see the U.S. EPA’s compliance resource entitled “ Profile of the Dry Cleaning Industry.”
Wet cleaning is desirable as an alternative because is uses only water, detergents, soap, sizing, and softeners, and does not produce hazardous waste (although some stain removal chemicals may be hazardous). Ultrasonic cleaning is being researched and developed as a possible alternative to traditional dry cleaning. Ultrasonic cleaning works by using the pressure of sound waves directed at a garment through a soap and water solution. The pressure removes the stains from the garments. Ultrasonic cleaning is also desirable because it produces no hazardous wastes or air emissions.
Carbon Dioxide Cleaning
Both supercritical and liquid carbon dioxide are being explored as methods for garment cleaning. Carbon dioxide technologies are desirable because they are non toxic, easily recycled, inexpensive, non-flammable, non-corrosive, and readily available. Liquid carbon dioxide is more favorable as it is safer than supercritical carbon dioxide.
Supercritical carbon dioxide works at high temperature and pressure. Grease and oils dissolve when exposed to supercritical carbon dioxide. Oil and grease can then be removed from the carbon dioxide and recycled by reducing the pressure. The carbon dioxide can then also be recycled.
Liquid carbon dioxide requires lower temperature and pressure than supercritical carbon dioxide. Liquid carbon dioxide can be combined with surfactants for more effective cleaning and can also be separated from dirt and greases and recycled.
The Topic Hub™ is a product of the Pollution Prevention Resource Exchange (P2Rx)
The Dry Cleaning Topic Hub™ was developed by:
Hub Last Updated: 2/26/2013