Should Cater to Carwash's Needs
A system should match wash equipment with operator's goals.
Recycling systems can be divided into three categories:
limited recycling (pumping stations, etc.)
multi-state filtration systems
The carwash industry includes several different types of wash operations, each with its own unique
needs and characteristics. These operations vary in the amount of water they use, the amount and type of
contaminants found and the chemicals used in their cleaning processes.
Given the above examples, it’s easy to see that water usage and wastewater characteristics in this industry are highly variable, depending not only on the type of carwash, but also on geographic location and time of year. For example, carwashes in northern climates have high loads of ice, salt and grit in the winter and spring months. All of these factors should be considered when choosing a recycling system.
For instance, a self-serve operator will use less water and have higher evaporation and carry-out losses than a tunnel wash, but the contaminants found in self-serve water will be more cumbersome. It is for this reason that “one size does not fit all” and each wastewater treatment systems should be engineered on a site-specific basis meeting the needs of each user.
On average, a self-serve facility uses 20 gallons of water per vehicle with a 5-10 gallon loss through evaporation and carry-out. Although the number of cars per day is relatively low, wash owners can expect to find almost anything in the water. The operator who sees farm equipment, off-road vehicles, boats on trailers and other vehicles coming into his bays will see heavily contaminated water that will require some form of treatment regardless of where it is discharged.
Tunnels can wash from 100 to 1,000 cars a day using an average of 80 gallons per car. This high water volume lends itself well to water recycling, since the water collection can be segregated in the trenches to permit separate treatment and reuse of wash and rinse water.
In-bay automatic carwashes often use friction and/or pressure along with chemicals to achieve a good quality wash. When comparing a friction-based operation to one that is pressure-based you must keep in mind that even though they are both in-bay automatics, they are completely different from a recycling standpoint:
Values of Recycling
Water recycling has many attractive benefits. The most beneficial is the substantial reduction in water consumption and sewer discharge costs.
For example, a carwash owner in south Florida who is currently using a partial recycling system is saving up to 80 percent on both his sewer and water bills. Prior to recycling, his utility expenses were averaging around $750 a month – they are now less than $200 per month.
The length of time before carwash operators can expect to see a payback depends on local sewer and water rates and the purchase price of the recycling equipment. Some carwash owners are able to get a payback after just a couple of months while others may take up to two years. New carwashes that make the decision to recycle can see an immediate payback in the reduction of impact fees alone.
Water restrictions are popping up all over the nation in some unimaginable areas. Hot summers this year and last have forced washes all over the country to close or restrict hours due to a lack of city water. In this scenario, not only does recycling and reusing save water, but it also gives a wash owner a sense of security that they can continue doing business as normal even under these restrictions.
Environmental problems and water shortages nationwide have public awareness at an all-time high. In response to this awareness, some carwashes are actually using recycling as a marketing tool. They are offering the concerned consumers a way to help “save the environment” without having to give up the luxury of a clean car.
Systems Vary With Needs
Limited recycling will typically provide minimal filtration of water, offering the carwash approximately 50 to 80 percent wash water reuse depending on the technologies used. These systems are designed to remove the heavy solids and give the operator wash-quality water for reuse.
In some situations, oxidation will be necessary to control the odors and bacteria growth. This is usually achieved either by the addition of an ozone system or by adding chlorine.
Multi-stage filtration systems can provide the carwash owner with 80 to 95 percent water reuse by incorporating the use of several water treatment technologies. The initial stage is designed to settle out heavy solids while separating oils from the wash water.
Once the water has completed this process, it enters stage two, where a majority of the filtration takes place. This stage typically incorporates aeration, filtration and ozonation to ensure the removal of dirt, oils and wastes while eliminating odors and organic buildup.
The final stage consists of several methods which filter, polish and re-pressurize the water just prior to feeding the carwash equipment.
Closed-loop recycling adds the final process of “total reuse” to the multi-stage filtration system to avoid any discharges to sewer or septic. This can be accomplished by several methods, which all have advantages and disadvantages.
Historically the early closed-loop systems filtered the water until it became too heavily contaminated with total dissolved solids (TDS), soaps or other contaminants. At that time it was hauled off-site and the process started all over. Other recycling system designs have incorporated the use of a small evaporator to burn off excess water regularly to permit the constant addition of fresh water.
Some recycling systems attempt to close the loop by creating rinse-quality water, which would eliminate the need for any new fresh water except to compensate for drive-off and evaporation. The important factor in all closed-loop systems is an awareness of the increased amount of maintenance and attention that will be needed to keep the system in balance.
Wash operators should talk to their equipment manufacturers and their water treatment professionals to help decide which system best fits the unique needs of the wash.
Full-service car washes come in a variety of shapes and sizes and may use a variety of chemicals. But regardless of these differences, the one consistent factor in all tunnel wash facilities is the large amount of water needed to operate them.
Brush-type automatics, with their lower usage of chemicals, generally have the easiest water to handle. With a water usage of between 30 to 45 gallons per car, this water is often reused successfully with minimal treatment.
Touch-free automatics consume a comparable amount of water per car, but the increased use of cleaning chemicals makes additional water treatment necessary before either reusing it or discharging.