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Less Toxic Auto Repair: Degrease with Aqueous

August 18, 2021

Most engine degreasers and brake cleaners contain petroleum distillates and other chemicals that are harmful to human health and the environment. These solvents may be used in enclosed parts washers, a simple bucket/small tank, or in aerosol form. Most are quite volatile and the fumes, or fine aerosolized particles (in the case of aerosol sprays) are released into the shop air, exposing and potentially harming employees. In addition, the volatile organic compounds (VOCs) present in these products contribute to smog formation.

Identifying economical, safer products within the local supply chain is challenging, especially with long-term supplier contracts for specific products.

Two aqueous alternatives are demonstrating equivalent performance to petroleum-based solvents without the toxic exposure, and eliminating most, if not all, solvent use and waste at some shops.

Ultrasonic washers use cavitation, or scrubbing bubbles, with an aqueous cleaner to remove grease from parts.  Enzymatic, or bio-based parts washers, use microbes in a slightly-heated solution to bio-remediate the contaminants, or break grease and oil down into carbon dioxide and water.

The Pollution Prevention Resource Center (PPRC) first learned of bio-based systems during a tour of South Seattle College’s (SSC) vocational auto repair shop. Use of aqueous degreasers allowed SSC to greatly reduce hazardous solvent use.  One of PPRC’s fellow technical assistance providers (TAP), the Toxics Use Reduction Institute at UMASS Lowell, shared this case study and testimonial video of Assabet Auto Tech’s vocational shop that converted to a bio-based washer and is saving over $3,000 per year with reduced solvent, PPE, and hazardous waste disposal.

More recently, PPRC visited an EcoBiz-certified auto repair shop in Oregon using a 30-liter ultrasonic unit and a dilute aqueous cleaning solution, essentially eliminating almost all solvent use on site. A second EcoBiz-certified shop expressed interest, and through an EPA grant, PPRC was able to procure an ultrasonic unit for them. Both shop owners are pleased with the systems and especially with reduced hazardous solvent exposure at the shop. The case study of these shops details their experiences, short payback, and presents tips for using ultrasonic cleaning in auto repair.

Simultaneously, the Minnesota Technical Assistance Program (MnTAP) has been working with the Leech Lake Band of Ojibwe, and was able to purchase and install one bio-based washer and three ultrasonic cleaners at four different repair shops.  They also provided recommendations to 21 auto repair shops on the Leech Lake Reservation. Overall, 13 vehicle service sites implemented less toxic degreasing alternatives, preventing the annual release of 1,200 pounds of VOCs (including 520 pounds of regulated hazardous air pollutants (HAPs)) and 51 pounds of solid waste from reduced usage of spray cans of degreasers.  Read more at Leech Lake Band of Ojibwe – Safer Degreasing Products.

There are several benefits of bio-based systems:  e.g., the solutions available for use in bio-based washers are often mild enough to wash parts by hand without gloves; Smart Wash SW-4, is suitable in most models and is Safer Choice certified and there are no wash residuals to dispose of as the bio-based cleaner and/or boosters are simply replenished as the volume diminishes over time.

Ultrasonic units are effective with a dilute solution of water and most any aqueous degreaser.  PPRC recommends searching for a third-party, environmentally certified product.   The photo below shows before and after cleaning performance with a 12:1 ratio of water to a Safer Choice all-purpose cleaner.  For ultrasonic units, consult local regulators to determine proper management of spent wash water, which in some cases, may require running through an oil-water separator, or other.

Washington auto repair shops: Your business may be eligible for financial reimbursement to replace hazardous solvent systems with aqueous, under Washington Department of Ecology’s Product Replacement Program!

Contact mgaither@pprc.org for more information.

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