Reclaim Technology Advances, but the Aroma Lingers
Operators can choose from a growing list of water treatment options

By Bryant P. Ruder

One of the most frequently asked questions in the carwash industry is, "What type of reclaim system should I look at?"

Some typical answers could be:

• Use a cyclone separator. ("No, I want to do more than that.")
• Bag it. ("Sounds interesting.")
• Pass the water through a media filter. ("Sounds even more interesting.")

These are just some of the options that are available to the vehicle wash industry.

Close-up view of a typical bag-type filter reclaim system.

The cyclone separator has been a part of the carwash industry for years. This is a simple way of spraying a lot of water onto a vehicle very inexpensively. With this method the water is not filtered, which means that much of the dirt and oil in the water is transferred to the cloth and the carwash equipment. The overspray water also sticks to the walls of the carwash tunnel. This results in a dark film on tunnel walls and equipment requiring constant cleaning.

Bag filter systems have made a successful appearance over the past couple of years. They are usually sold skid-mounted and fit into just about any equipment room. The skid includes a pumping station with controls. When the carwash calls for water, the pump starts and distributes water to the different pieces of equipment.

The bags are constructed from a cotton material, the weave of which is meshed to different sizes allowing for options in micron size. The tighter the weave, the finer the filtering.

The solenoid valves on this media filtration system allows the reclaim unit to backflush automatically.

High pressure pump manufacturers recommend 10-micron water or less feeding their pumps. Something to remember: the smaller the micron requirements, the more often the filter bags will have to be cleaned or replaced.

When the filter bag is full it acts like a vacuum sweeper--the flow becomes restricted. Since the filter bag is designed to catch the dirt in the water, don't be discouraged when you have to clean or replace the bags. This is what it is designed to do--filter dirty water. Seasonal washing, geographic conditions and water volumes determine the frequency of bag replacement.

The filter bag canisters have lids that are easily removable. This allows for quick replacement of the bags. If you have a bag filter system that has two different mesh bags in it, the larger micron-sized bag is usually the first filter. This filter catches most of the large dirt particles. The second filter, normally with a smaller micron range, filters to the final level.

Media filtration or depth filtration is another filtration option. Pit water is sucked from the reclaim tanks by a pump and pushed through a filter media. Since all of the water is forced into the media tank the water must be filtered. After the water has been filtered it can be stored for use or sent directly to the vehicle wash equipment.

One problem with depth filtration is the water being filtered soon creates a path that most of the water follows. This is called channeling. When channeling occurs the water quality is reduced, due to the lack of water contact with the filter media. Backflushing the filter bed reduces channeling. Backflushing causes the flow of water to be reversed, resulting in the media being lifted, breaking up the route and thus eliminating the channeling. The backflushing sequence should be automatic.

There are several different filter media options being used with this type of filtration. The most popular are activated carbon, diatomaceous earth, silica sand and glass. The activated carbon and diatomaceous earth are considered porous filter media, which absorb impurities. As the pit water passes through the media bed, the particles begin filling the voids of the filter media. Eventually, backflushing will not remove the impurities and the filter media will need to be replaced. The frequency of replacement depends on the carwash volume, seasonal conditions and geographic location of the carwash.

Silica sand and glass are non-porous filter media. They filter by having each separate piece of media set or laid next to each other, trapping the impurities in the filter bed. During backflushing the dirt is released and the filter flushes clean. Heavy oil loads can cause the filter media to clump together and stop filtering. Backflushing the contaminated media may not break up the clumps and media replacement will be required. Proper pretreatment of the reclaim water prior to filtering will reduce media contamination.

The lids on these filter bag canisters are easy to remove, allowing for easy replacement.

Odor control is a particular area of concern in water reclamation. Should the reclaim water be treated with bleach, fragrance or ozone? Whatever treatment is used, be sure it is automatic. Don't wait until you smell the odor and then react to it. By the time the odor has gotten into the carwash hallway and then into your office, several of your customers have already left with this unpleasant odor permeating their vehicles.

Some believe a cure to this problem is to circulate the pit water in order to eliminate odors. What this actually does is aerate the water--which feeds the odor-causing bacteria. When the flow stops, the bacteria start growing again. Most operators only treat their reclaim system for odor during the summer months, but it is a year-round occurrence--bacteria do not take the winter off. Due to the colder water the bacteria simply do not grow as fast, but the smell is still there.

Bleach fades quickly

Bleach has been used for years to reduce the morning smell that comes from the carwash since it kills the bacteria that cause the unpleasant odor. Unfortunately bleach has a short life span when dumped into several thousand gallons of dirty water. Bleach may also alter the pH level of the reclaim water, which can affect the cleaning process. If you are adding bleach to a reclaim system that is using activated carbon filtration, the bleach is absorbed into the reclaim filter media once the water starts flowing.

View of the distribution plumbing in a typical media or depth filtration reclaim system.

Pouring a fragrance into the center trench and reclaim tanks works for awhile, but again, due to the volume of water in the reclaim system, the fragrance is consumed rapidly. Using a metering pump to add the deodorant into the pits during business hours would be the best.

The third and easiest method to control odor is to add an automatic ozonator to your carwash. There are several different ways to produce ozone. Ultraviolet light and corona discharge are the most common.

Ultraviolet (UV) light can actually be used two different ways. One technique is to have the reclaim water pass over a water jacket. The jacket keeps the lamp dry and allows the UV light to kill the bacteria that causes the odor. With this setup, no ozone is actually used. This process has a downside: the reclaim water is normally dirty and the dirt film attaches itself to the water jacket. When this happens, the UV light cannot penetrate the film and the disinfecting stops. The water jacket requires constant cleaning.

The other UV application requires air to pass across the lamp, which discharges ozone. By pumping or sucking air across the lamp's surface, you can inject the ozone into the center trench or reclaim pits. Thus, UV technology works well in damp as well as dry conditions. Typically, a UV lamp will produce 1-2 grams of ozone, which is sufficient to eliminate pit odor.

Corona discharge produces ozone from an arc generated by a high voltage and low voltage electrode. Once the ozone is produced it can be injected in the same manner as the ultraviolet ozone. Corona discharge can produce larger amounts of ozone. This process requires dry, low humidity air. These conditions are not always available in carwashes. An air prep is required in front of the corona discharge units to pretreat the air before entering into the ozone chamber. When the air is not properly treated the efficiency of the unit is affected.

There are several different ways of introducing ozone to a carwash reclaim system. While circulating the reclaim pit water, a simple venturi injector can introduce ozone into the water stream. This flows throughout the reclaim settlement tanks, reducing the odor. Bubbling ozone into the settlement pits is another way of introducing ozone into a reclaim system. The tiny bubbles have contact with the water thus reducing the reclaim odor.

Bacteria will return

Ozone is effective for roughly 20 minutes once introduced into water. Overnight, the bacteria typically start growing again and the odor returns. When filtered water has been pumped to a holding tank the odor can return. The only way to stop this would be to drain these tanks every night or before you open, turn on the equipment that reclaim water is used at and purge the system with refreshed reclaim water.

There are several manufacturers of reclaim equipment who can provide information on different systems. Discuss your needs and any restrictions that you are working with. Don't ask the price and buy the cheapest package. Most likely you will not achieve the goal that you set for your operation. In some locations the reclaim package may equal the cost of the equipment package, especially if you need a true closed loop, "zero" discharge system.

The costs of water and sewer are increasing. Reviewing your past water and sewer bills, you can see a positive return from your filtration reclaim investment. Purchase the equipment that allows you to grow, not the equipment that addresses only your current needs.

Bryant P. Ruder is vice president of the Car Wash Division of Sobrite Technologies, Inc. in Eureka, IL. He can be contacted at (800) 762-7483.

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