Background:
Dry-cleaning is the process of garment cleaning with organic solvents instead of water. Most dry-cleaners are located in urban areas and may also be found in laundries, to supplement wet processing.
Since the late 19th century many different solvents have been used such as camphene, benzene, white spirit, benzine, tetrachloromethane, trichloroethene, chlorofluorocarbons and tetrachloroethene. The latter, also known as perchloroethylene (PER, Perc or PCE) or tetrachloroethylene has been the dominant dry-cleaning solvent used in the UK from the 1950s to the present day. Hydrocarbon solvents and siloxanes are used in some instances.
Potential Processes and Operations:
Most dry-cleaning machines are built around a main cage in which the garments to be cleaned are placed. Typically, a dry-cleaning cycle consists of an initial solvent wash, followed by a spin to remove the solvent, then a rinse in distilled solvent and further spin cycle and a final drying with warm air. The cleaned garments are then removed from the cage.
A small quantity of water and non-ionic, anionic or cationic detergents may be added to improve cleaning performance by removing water-soluble stains.
Dry-cleaning machines often incorporate solvent recycling operations and the main waste generated during dry-cleaning is the liquid still residues that remain after such operations. Still residues are either removed manually from each machine or pumped directly to a waste storage vessel.
Wastewater from any water/solvent separators is normally piped into a settling tank and may be treated prior to disposal to foul sewer.
Potential Contaminants of Concern:
| Contaminant type | Main group of contaminants | Location | |||
|---|---|---|---|---|---|
| Solvent storage and pipework | Process areas | Drainage conduits | Waste storage/disposal | ||
| Organic | Volatile organic compounds (VOCs) | • | • | • | • |
| Halogenated hydrocarbons | • | • | • | • | |
| Non-halogenated hydrocarbons | |||||
| Polycyclic aromatic hydrocarbons (PAHs | |||||
| Dioxins and furans | |||||
| Polychlorinated biphenyls (PCBs) | |||||
| Pesticides and herbicides | |||||
| Organometallic compounds | |||||
| Explosives | |||||
| Per- and polyfluoroalkyl substances (PFAS) | • | • | |||
| Persistent organic pollutants (POPs) | • | • | |||
| Inorganic | Metals | • | • | • | |
| Non-metals and common inorganic substances |
|
• | • | ||
| Asbestos |
|
||||
| Cyanides |
|
• | |||
| Radionuclides | |||||
| Other potential contaminants of concern |
Siloxanes are used as an alternative solvent. | ||||
- Guild of Cleaners and Launderers - Technical bulletin (2015)
- Defra Process Guidance Note 6/46(11) - Statutory guidance for dry cleaning (2014)
- CL:AIRE Technical Bulletin 22 - An overview of the uses of PFAS to assist with identification of sites of concern (2023)
- US Association of State and Territorial Solid Waste Management Officials (ASTSWMO) - Conducting Contamination Assessment Work at Drycleaning Sites (2010)
