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Improving wash water quality

October 11, 2010
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In the past, installing reclaim equipment and using it in the everyday operation of washing cars was second choice.

Most of the complaints stemmed from early methods of recycling. Re-using spent water involved sucking water from a single mud tank prior to sewer.

Equipment in the 1980s and 1990s was cumbersome and expensive to purchase and maintain. Since the cure cost more than the problem, the purchase of the reclaim system could not be justified.

Savings
Reclaimed water is water that is recovered and treated to a point to make it acceptable for use in the wash portion of the total wash and rinse process. Reclaimed water should be used as the muscle to remove the solids from the vehicle, followed by a fresh-water rinse and in some locations a post rinse of spot-free water.

The spot-free final rinse will remove the dissolved solids found in 90 percent of all freshwater sources. The use of three different sources of water will deliver the most desirable results.

From a cost standpoint, being able to recover 80 to 90 percent of your total water usage is a substantial, not to mention the expense for the sanitary sewer that is normally more than the cost of the water.

Total the cost of the recovery unit and the expense to implement the system in your location. The average savings in sewer and water can range from 50 to 90 percent, depending on the amount of fresh water that can be converted to reclaim.

When contemplating building a new facility, be sure to contact the municipality or utility provider that will service your anticipated location. Find out the cost of water and sewer for the size meter you will be using, any impact fees and, of course, any planned rate hikes in the near future.

Bacteria issues
Once you’ve determined if reclaim can be a definite benefit financially, it is time to discuss methods of implementing a system.

By law, carwash soaps and solutions are manufactured to be biodegradable. For most tunnel operators, the reclaim water remains on cloth equipment overnight. Bacteria will grow rapidly and cause the green, brown and black residue found on the cloth. Most of this buildup is caused by the rapid growth of bacteria in the degrading process.

Equipment holding reservoirs that hold reclaim water overnight will grow a black, leafy substance at the water line. This slimy growth will continue to grow during nonuse periods.

The odor you smell for the first few cars every morning is caused by the oxygen-starved bacteria. This dead bacteria is what produces hydrogen sulfide odor (rotten-egg smell). This odor, combined with the residue left after the evaporation, gives potential reclaim users mixed signals. Are the large savings on water, sewer and related fees worth the problems that accompany the recovered water?

Nothing is easier than using fresh water for all applications; however, the ongoing non-refundable cost is staggering. If you want a gut-wrenching experience, try totaling your last five years of water and sewer bills.

Solutions
A cheap and easy fix for overnight bacteria growth is to tee a fresh city water line into the reclaim line. The city line would have a ball valve or electric valve.

An inexpensive timer or the carwash controller could actuate the electric valve. At approximately 10 to 15 minutes prior to closing, the solenoid valve would open. City water would enter the reclaim lines, and the chlorine in the city water would kill the bacteria that normally cause the buildup on cloth, equipment, walls, floor and pumping station reservoirs. After the carwash closes, the valve would shut off and revert back to reclaim for the next day’s operation.

Some operators inject a small amount of city water into the flow of reclaim. The chlorine in the city water will tend to lighten the color of the reclaim water, keeping it from turning septic in holding tanks and keep odors at a minimum.

Blending is similar to using a home shower valve. You can mix reclaim and fresh city water much like hot and cold to suit the particular application. For example, there would be no need to blend for washing under the car or tire/wheel cleaning. Blending valves could be installed on high-pressure pumping tanks or on spray tips that are aimed on mitters or other cloth close to the exit of the wash process.

Keep in mind that every drop of reclaim water that is used is a drop you are not going to pay water or sewer charges for. If blending uses 25 percent city water and 75 percent reclaim, you have lowered your monthly bill dramatically.

The bottom line is to be creative. You can have the best of both, low water and sewer bills and good quality reclaim water.


Jim Keller, (info@conservwater.com) is president of Con-Serv Manufacturing.

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