Most of the time, a car wash decides to reuse water because it makes financial, environmental, or legal sense to do so. The Clean Water Act makes it a law that car washes collect and properly get rid of their garbage.
Also, the US Environmental Protection Agency has made it illegal to build new drains that link to wells for getting rid of old cars. Once this rule is put into place, more car washes will have to look into reclaim methods.
Trichloroethylene, which is used in some grease removers and other substances, and benzene, which is used in gasoline and detergents, can be found in the waste stream of car washes.
The following ways are used in most reclaim systems: settling tanks, oxidation, filtration, flocculation, and ozone.
Most car wash recovery systems will provide water that is good for washing cars. This water will have a particle size of 5 microns and flow at 30 to 125 gallons per minute (gpm).
A variety of pieces of equipment can be used to meet the gallon flow needs of a normal building. For instance, high-concentration ozone treatment of water held in holding tanks or pits can get rid of the smell and color of recovered water.
Before you build, install, and run reclaim systems for your clients’ car washes, you need to find out whether they can connect to a sewer and whether they want to use an open or closed-loop system.
A general rule says that most uses can work in a closed-loop system: the amount of fresh water added to the wash system shouldn’t be more than the amount of water lost through evaporation or other means.
When you wash your car in different ways, you will lose different amounts of water. As the last step in the wash process, fresh water will always be added to make up for water loss through carry-off and evaporation. The last rinse brings back the water that was lost. To get rid of any leftover recycled water from the wash process, the last rinse pass should always be high pressure and low volume.
If there is sewer access at a car wash location, water cleaning equipment can give owners more options for which parts of the wash process will use recycled water and which will use fresh water. The choice will likely be based on how much the sewer use fees and tap or wastewater capacity fees are.