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Environmental Issues

Water recycling made easy

October 11, 2010
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A few decades ago most carwash professionals wouldn’t have considered trying to reuse waste water from their carwashes. Water appeared to be overly abundant, cheap and there weren’t many regulations about using all the water you wanted and simply dumping it down the drain. In addition, there weren’t many companies offering reliable technology to reuse the water.

Today, it’s not uncommon to pay two to three times the amount of your water bill as a fee for discharging your used water to the sewer. At some washes, this combined water and sewer bill can cost several thousands of dollars every month.

Federal, state and local regulations pertaining to what is in the water being discharged are highly evolved, becoming more and more restrictive, and monitoring of carwash discharges is certainly on the rise. At our own washes, we had county regulators monitoring our discharge with automatic sampling machines month after month. Pity to the operator that is out of compliance with the local sewer discharge ordinances!

Municipalities are finding it difficult to allow more carwashes to build, citing limited water supplies and sewer processing capacity as major concerns as they struggle to supply adequate water and sewer services to our nations burdening population. Some cities are mandating 80 percent recycling as part of the permit consideration process for new carwashes.

Increased recycling choices
Technology has certainly changed in the industry, as well. Several years ago, about all you could find in the marketplace were inline filter vessels, typically containing a high maintenance filter bag that required frequent and expensive changing.

Today there are a multitude of technical approaches to recycling your waste water. There are biological systems, cyclone filters, UV light systems, chemical precipitation systems, automatic back-washing filters with numerous types of media filtering a wide range of particle sizes, there are ozone systems, and bag filters.

With all of these various options available to the wash operator, how is one supposed to know which approach is the most effective and desirable for your particular wash?

Fortunately, the information age, along with a whole new breed of wash operator has emerged. With the advent of the internet you can find just about anything you desire. Savvy operators use this research tool to find qualified suppliers. Operators are better educated today, thanks in part to the availability of information and tools such as the internet.

Choosing the right system
In my opinion, there are five primary questions to consider.

1. How much water volume does the recycling system have to provide to meet my site requirements?

You have to have an understanding of the volume of water each washing equipment component will use in order to size the recycling system properly. When adding up the volume of water your equipment is using, try and plan for the future a little here. Maybe you’ll want to add another high pressure spray arch later, just think through it carefully and don’t buy a smaller system than you really need. Allow for a little expansion if possible.

2. Will the system remove the contaminants to a level that won’t damage my wash equipment?

Lots of washing equipment involves high pressure pumps that have very tight tolerances. Pumping recycled water with 50 micron particles in it would be similar to running your car engine with very dirty oil. These particles will certainly shorten the life of your washing equipment. In fact, we’ve heard of some pump suppliers voiding the warranty if the solids in recycled water aren’t removed to less than 20 microns. In this particular instance, smaller is better. Don’t settle for an unsubstantiated claim here either; a claim is just a claim, ask for some form of proof of filtration removal.

3. Will the water have a foul, offensive odor that might drive my customers away?

Bacteria are very opportunistic. Carwash waste water is full of nutrients and if left standing, even for a short time, bacteria will grow. It’s this bacteria and its short life cycle that cause the terrible odor. There are numerous ways to control bacteria. You can add a biocide, like chlorine, to the water. However, you’re already buying enough expensive chemistry for your wash. You don’t need to be buying even more.

Certain biocides can also be dangerous and difficult to handle safely. A better way is to produce the microbiological control agent onsite to kill these little beasts.

UV light and corona discharge generators are the generally accepted methods for this task. UV light has kill rate disadvantages and the ongoing expense of replacing the light bulb that generates the biocide. Plus, the effectiveness of the UV systems degrades rather quickly over time, so they work, but they don’t last.

Corona discharge ozone generators are my preferred approach for handling these pesky little creatures. It’s reliable and highly effective, if, and only if, the corona system is designed properly.

In fact, I was recently involved in a detailed study of corona discharge systems and found that most generator suppliers actually provided a corona discharge system that met their ozone production claims. However, they only produced what they claimed for a short time, in some cases for just a few minutes immediately after the system was turned on. Once these systems get hot, the ozone production dropped off dramatically.

Sizing an ozone generator is both a science and an art. Leave the sizing to the supplier. They should know enough about ozone demand and oxidation loading in a carwash application to size the system properly.

4. What are the maintenance requirements and costs?

While a pump and bag filter housing system will be much cheaper than buying a system that treats water, you have to be prepared for the replacement of the bags.

Some operators prefer automatic and self-cleaning systems that don’t require ongoing addition of any chemistry. The idea here is to minimize costs, not to add to your ongoing purchase of chemicals.

5. Consider the manufacturer’s capabilities.

Does the manufacturer of the recycling system have the technical resources and experience to support your project both before and after the sale? Do they have on staff technical support available to assist you with the permitting process? In many areas, the sewer impact fee can cost you tens of thousands of dollars.

A reputable and technically competent supplier can prepare a very strong technical argument to present to the permitting authority that can, in many cases, get this upfront fee significantly reduced, sometimes by as much as 75 percent.

This savings can help offset the capital expenditure for the recycling system, perhaps even reducing your out-of-pocket expense enough to pay for the entire recycling system. This is truly a win/win situation. You get the benefit of substantially reduced out-of-pocket expenditure and you get the ongoing savings associated with reduced water and sewer fees.

Another important issue is support after the sale. While your local distributor will assist with any mechanical issues, the company behind the distributor is paramount.

You may need a reliable source for ongoing technical support from competent professionals in case unforeseen problems arise. Having a solid company with experienced on-staff support means you’re only a phone call away from assistance.

Future destinations
Carwashing is still the great business today that it has always been. Technological improvements to equipment have made their impact in all phases of the business, including water recycling technology. The key to which equipment you purchase lies in what you want to accomplish for your business.

In my experience as an operator, there was no debate. Hands down, recycled water was far more beneficial to my business than poorly filtered water. My cars and washes were cleaner, the water and sewer bills were substantially reduced, my equipment maintenance was significantly less and, most of all, my customers were happier. After all, isn’t that the name of the game?

Robert Harvey is a chemical engineer with 28+ years experience designing, fabricating, installing and permitting industrial water treatment and recycling systems. He can be reached via email at: or by phone at: 770-662-5610.

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