Beyond Reclaim: How to Deal with Dirt and Sludge

Your dream is about to come true – you can finally start building your carwash. You have finished the process (or so you think). The architect is finished with the plans; the civil engineer has approved them; you have your permit; you have selected the carwash equipment (after talking with everyone who manufactures carwash equipment); you have chosen the chemical supplier; and you are ready to go. But wait! What about the reclaim? There are more questions to ask. Do you pour it in place? Do you use pre-cast vaults or do you use septic tank vaults? Manhole steel covers, round fiberglass or hinged steel covers? What about pumping out the reclaim? How often will you do it? What does it cost? Sadly, not enough distributors can answer all these questions.

Ever since the first carwash began using reclaimed water for the wash cycle, one of the biggest problems was how to remove the dirt, sediment and sludge that settle in the bottom of the vaults or holding tanks. The only efficient way was to have the local septic-tank company come every three to four months, after closing for the day, and completely remove the water, sediment and sludge at a cost of $1,500 to $2,000 each time it is performed. But there is an alternative to all of this.

A sediment- and sludge-removal system operates by placing a pump in each of the first two reclaim compartments, as this is where most of the sediment and sludge settles. Each hour, the first pump is automatically turned on (with a programmable controller) and runs for a period of 30 to 40 seconds before it shuts off. After 15 minutes, the second pump is activated and runs for 25 to 35 seconds. The reclaim water and sludge is pumped to a bagging system that retains the sediment while the reclaim water leaches back to the first vault compartment or is sent directly into the conveyor trench or catch-basin. It’s possible to integrate more pumps into other vaults, as well.

In either a conveyorized tunnel or an automatic rollover, the filter bag cabinet can be placed in the wash area or on a concrete pad along an outside wall. The leached water can then be directed to the conveyor trench, catch-basin or back to the first reclaim compartment. The cabinet can also be placed alongside the building; it is not recommended that the cabinet be placed in the equipment room. The filter bags, on average, are changed approximately every four to six weeks, though it depends on the time of year and the volume of vehicles washed.

Here are some answers to common questions concerning sediment- and sludge-removal systems.

• How is the sediment disposed? We have found that, 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 landfill or directly into the dumpster, according to local ordinances.
• What about controlling odor, petroleum hydrocarbons and other organics? Gaining the primary ingredients in the elimination of odor is accomplished by incorporating aeration along with enzyme- and bacteria-soluble packets. These enzymes and bacteria, which are completely safe to humans and animals, consume the food source of the odor-causing bacteria (petroleum hydrocarbons and other organics), turning them into safe carbon dioxide and water, and also eliminating odor.
• Why not incorporate ozone or UV light? Both of these processes kill the bacteria but do not eliminate the most hazardous materials, among which are petroleum hydrocarbons and other organics. The advantage that enzymes and bacteria have over these processes is that the hazardous materials are consumed and then turned into harmless carbon dioxide and water.
• What about the Total Suspended Solids (TSS) in the reclaim water? The TSS are dramatically reduced when incorporating both systems.
• What about the Environmental Protection Agency? We have run tests of reclaim water at various carwashes and have found that within a short period of time, diesel and oil hydrocarbons can easily be controlled to 100 parts per million and fewer within a very short time – even a week or two.
• What is the return on investment? Without such a system, an operator could pay $1,500 to $2,000 every three months to pump the reclaim vaults. Considering this, a sediment- and sludge -removal system should pay for itself in less than two years.