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Water Treatment - Five Key Concepts to Consider

By John Gibney

05/01/19

Vehicle wash owners considering investing in a water recycling system for a new or existing location will benefit from learning more about the following five key concepts. The right water recycling solution will save more money, time, and the environment. The following are the top considerations before making a purchase.

1. TYPES OF WATER SYSTEMS

Reuse

This system utilizes three or more settling tanks to separate out most of the solids via gravity. Water is pumped back to the wash equipment for re-use from the last stage of the settling tanks. The water this system delivers contains suspended solids and also all the chemicals used in previous washes. In warmer weather, when this water is re-used, it will contain a rotten egg odor that is a gas emitted by the natural, anaerobic microbes in this water.

Reclaim

The wastewater in a reclaim system is sent through a series of settling tanks, similar to the re-use system, to settle out the heavy solids using gravity. When the water is pumped out of the last settling tank it is processed through a form of filtration, or cyclonic separation, to further reduce the solids to a micron level. This water is then treated with ozone, UV, zinc, or copper oxide to kill the natural microbes in an attempt to keep the water from having an odor when re-used. The water coming from a reclaim system still contains most of the chemicals that were used in previous washes. Used chemicals are not removed in a reclaim system, so there are limitations to where this water can be successfully re-used in the wash. The majority of the water system brands in the vehicle wash industry manufacture systems within this category.

Restoration

A water restoration system utilizes the same settling tanks as the re-use and reclaim systems. When the water is pumped from the last settling tank, it’s sent through hydro cyclones that cyclonically separate any remaining solids down to 5 micron. The wastewater is aerated, which creates an environment where aerobic microbes are present. Aerobic microbes are 90 percent more aggressive in consuming chemical waste in the water. When aerobic microbes consume waste in the water, they give off a CO2 gas that has no smell, so odor is never an issue when the water is reused. In the last step in a restoration system, the wastewater is sent through a biologic chamber where active aerobic microbes are grown to consume the chemicals in the water. With the chemicals removed, the water has been restored and can be re-used in all functions in the wash, with the exception of spot-free rinse water. In this system, 100 percent of the water captured can be reused.

Restored Spot Free

As technology has advanced, a new system has emerged that enhances the restoration system one step further. A restored spot-free system takes water from a full restoration system, processes it further, then sends that water to a reverse osmosis system to produce spot-free rinse water. This system provides the operator with the ability to use biologically restored water in all the stages of a wash.

2. OZONE VS. AERATION

Ozone-based water systems inject ozone gas and/or hydrogen peroxide into the process water to mitigate odor and chemically break down the used car wash chemicals. Using one or both of these substances kills off the very microbes that remove odor and consume used vehicle wash chemicals. As a result, the used wash chemicals remain in the processed water in an ozone-based system. Also, ozone systems require ozone gas replenishment and parts replacements — both of which can be quite costly.

Aeration-based water systems infuse oxygen into the water to mitigate odor and it also aids in the conversion of anaerobic microbes to aerobic microbes. The byproduct of this conversion is CO2 (which has no odor) and H20. Further processing sends the water through a biologic tank where the used wash chemicals are removed from the processed water. An aeration-based water system is completely safe to operate and requires quarterly nutrients and annual aeration air filter change.

3. CHEMICAL BIODEGRADABILITY AND COMPATIBILITY

Be sure your chemical supplier understands chemical biodegradability and compatibility. Wastewater coming from a vehicle wash contains chemicals, which consist of cationic, anionic, and nonionic chemicals. Most chemicals used are biodegradable. However, the time it takes to biodegrade varies. It’s very important that chemical manufacturers know and understand the biodegradability and compatibility of their chemicals when used in a natural biological water restoration or reclaim system.

Biodegradability of chemical components is classified by three terms:

Readily Biodegradable

“Readily” biodegradable means that the natural microbes present in the water can easily biodegrade the chemicals and turn them into CO2 gas and water.

Slow To Biodegrade

“Slow” to biodegrade means it requires high levels of oxygen concentration in the water and time for the microbes to biodegrade the chemical components. Slow-to-biodegrade components are difficult to use in a biologic treatment system. This is because there isn’t enough time for them to biodegrade before more of the same components are added to the wastewater. As a result, the concentration of these components continues to rise until the system is overwhelmed.

Not Biodegradable

“Not” biodegradable means these chemical components cannot ever be used in a biologic treatment system. These are chemicals that will kill the microbes.

The last factor that impacts the ability of bacteria to break down and biodegrade chemical components is whether the chemicals are anionic, cationic, or nonionic. Nonionic and cationic chemicals will readily mix together and be biodegraded by microbes. Anionic chemicals are not compatible with nonionic or cationic chemicals. When anionic chemicalsare used, the resulting mixture is very difficult for natural microbes to biodegrade.

4. DETERMINE ROI

After receiving quotes for a water recycling system, check the payback or return on investment (ROI). Typically, manufacturers will do a cost analysisfor you, but if they don’t, here’s how to calculate your ROI.

The first step is to find out what the city water and sewer costs are per measurable “unit” in your area. Cities measure a “unit” as either 750 gallons or 1,000 gallons, which will be shown on the water and sewer bill.  Once you know these costs, you can calculate your annual water and sewer costs. 

A water reclaim system will save you 45 percent of that cost, while a water restoration system will save you 85 percent of that cost. Therefore, to make the calculation, you would take your annual water savings and add that to your annual sewer savings to get your total annual savings. Divide the capital cost of the water recycling equipment and installation by your total annual savings; this gives your payback in years. After the payback in years of your capital cost, your total annual savings would drop to your bottom line as profit.

5. DO A SITE VISIT

Once you’ve narrowed your selection to one or two brands, a site visit will be highly beneficial. Most manufacturers will give you access to customers in your area, so that you can visit the site and see the system you will be purchasing in action. Ask the wash operator questions and take a look at the equipment. If you can get a sample of the water, do so. How does the facility look? Are the wash equipment and walls clean? How’s the quality of the vehicle wash product they are producing? Your active due diligence is well worth the effort.

 

John Gibney is the vice president and general manager for Aqua Bio Technologies, leading manufacturer of biologic water restoration, restored spot-free, reclaim, rain harvest, odor control, and reverse osmosis systems. John has 11 years in the vehicle wash industry. He can be reached via e-mail at jgibney@aquabio.co or phone (877) 881-9141 x 801.



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