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Ever since the first carwash began using reclaimed water for the wash cycle, one of the biggest problems has been removing the dirt, sediment and sludge that settles in the bottom of the vaults and holding tanks.
Back then, the only efficient way was to have the local septic tank company come every three to four months (if you even did it that often) after closing hours and completely remove the water, sediment and sludge at a cost presently of $1,500 to $2,000 each time it is performed.
Today, a variety of systems exist to make cleaning carwash tunnel pits an easier process. One system uses a pair of pumps in the reclaim compartments to remove reclaim water and sludge into a bagging system.
How the system operates
A pump is placed in each of the first two-reclaim compartments where most of the sediment and sludge settles. Every hour (every two hours after closing) the first pump is automatically turned on with a programmable controller and runs for a period of 30-40 seconds then shuts off.
After a period of 15 minutes, the second pump is then activated and runs from 25-35 seconds. The reclaim water and sludge is pumped to a bagging system that retains the sediment, while the reclaim water leaches either back to the first vault compartment, or, is sent directly into the conveyor trench or catch basin. More pumps can be integrated into other vaults if desired.
In either a conveyorized tunnel or an automatic rollover, the bagger is placed in the wash area. The leached water can then be directed to the conveyor trench or catch basin. The bagger can also be placed alongside the building; it is not recommended the bagger be placed in the equipment room.
Filters, odors and using organics
Depending on the time of year and the volume of vehicles washed, the filter bags on average are changed approximately every four to six weeks. By eliminating the petroleum hydrocarbons and organics it is acceptable to lay the filter bags on a drying rack (such as a strong wooden pallet) for a period of a few days and then dispose of them in a land fill or into a dumpster according to local ordinances.
The primary ingredients used in the elimination of odor are accomplished by incorporating aeration along with our proprietary enzyme/bacteria soluble packets. These enzyme/bacteria, safe to humans and animals, consume the food source of the odor causing bacteria. This bacteria, petroleum hydrocarbons and other organics, are turned into carbon dioxide and water, eliminating odor.
What about the TSS (total suspended solids) in the reclaim water?
TSS are dramatically reduced when incorporating both systems, on average to 150/180 ppm. Tests of reclaim water at various carwashes have shown that within a short period of time, diesel and oil hydrocarbons can be controlled to 100ppm in a short time – less than one month.
At an estimated a cost to the operator of $1,500 to $2,000 every three months to pump the reclaim vaults, this system will pay for itself in less than two years.
Andy Pazz is the owner/operator of Laguna Ltd., www.laguna-ltd.com. With over 30 years in the carwashing industry, Pazz started Laguna Ltd. in 1995. He is also the author of “How to Build a Successful Exterior Tunnel Carwash.”