We have talked several times about reclaiming and reusing water in the car wash. We’ve discussed ways to size the reclaim system based on number of cars, wash volume, and water used per vehicle; how reusing reject water from your spot-free rinse system is an easy way to get two uses out of a gallon of water you were just putting down the drain anyway. We have looked at ways to maximize the effectiveness of your spot-free rinse while minimizing the volume of that rinse. If this is the first article about water reclamation you have ever read, and have no idea what I am talking about up until now, below you will find a short primer on water use in car washing in general and reclaim-water use in particular. Then we will answer the yucky stuff question and why your wash location may be partly to blame.
For vehicle washing, water is the primary means of rinsing the dirt, road grime, salt, and snow off the surface of the vehicle during the wash process. All soaps use water as the delivery medium from the chemical station out to the vehicle to assist in breaking up those contaminants. The higher the quality of water you use the higher the quality wash you will deliver.
There are three types of water used in vehicle washing:
1. Fresh water/tap water, either from a municipal water supply or private well. It ranges in quality from great to terrible. Two of the symptoms of poor quality tap water are high TDS (total dissolved solids) and either too high or too low of a pH reading. Simple tests conducted at the site by a car wash equipment representative will help with determining the quality of the fresh water. Water is an increasingly expensive commodity, and fresh water use in a vehicle wash application should be carefully considered, and applied so as to maximize its value.
2. Spot-free water, which has, either naturally or by processing, a TDS count below 20 PPM (parts per million). The overwhelming majority of spot-free systems in current use are reverse osmosis. RO systems have an impact on water conservation as most equipment will require two gallons of fresh or tap water to make one gallon of product. There are ways to reuse this extra gallon of “reject” water. Talk to your car wash equipment representative about how to reuse that reject water.
3. Reclaim water, i.e., water that has been used in the wash process, then cleaned, and reused. Many municipalities now require some form of reclamation or recycle system prior to permitting and having such a system may assist in avoiding expensive impact fees. You may ask whether you can recycle all of it in a “closed loop.” For wash quality it is always better to have some fresh water in every cycle — 90 percent is for practical reasons about the highest usage recommended.
Okay, now that everyone is up to speed, let’s tackle some yucky stuff scenarios. There are several ways your reclaim water may become problematic or even unusable to wash vehicles.
One of the more common ways to shorten the effectiveness of your reclaim water is to put the brine discharge from your water softener into your reclaim tanks. For every cubic foot of resin in your softener it takes 60 gallons of water and 15 pounds of salt to regenerate. Most of that salt will stick to the resin for the purposes of softening water. Some of it, to the average of about 4,000 PPM of sodium chloride, will go down the drain as the brine discharge.
If you have a softener direct the brine discharge to the sanitary sewer directly.
So at a site with a moderate sized softener, 10 cubic feet of resin times 60 gallons of brine discharge per cubic foot, that is enough salt to raise the sodium chloride level in the 4,500 gallons of water in the reclaim tanking system by 530 PPM. The softener flushes twice a week, raising the salt level by more than 1,000 PPM a week — wash quality to suffer shortly. Please, if you have a softener, either direct the brine discharge to the sanitary sewer directly, or at least past the reclaim tanks to the oil/water separator.
Salt used on roads to melt ice for safety is often washed off cars in states where salt is allowed. The Northeast, Midwest and Plains states have lots of areas where this is done; this is geographic problem. The salt will build up in the tanks quickly and the only real solution is dilution. For instance, on snow weeks, run one day a week on fresh water. That will dilute the salt in the tanks and enable the wash to keep cleaning customers’ cars well.
In California, and some other places, they don’t allow salt for ice removal, they use sand, and in parts of California you are not allowed to use a softener with brine discharge, so in those areas your geographic location kept you from being a road salt victim and helped you from making the softener-brine-discharge mistake. It is outside the scope of this article to discuss all the ways being geographically located in California is a hindrance to your car wash or any other business for that matter. But if you want to discuss that, look me up at the Car Wash Show in Las Vegas April 4-6, 2017.
Road Salt Alternatives
In the areas where they don’t allow salt for snow removal, they sometimes use magnesium chloride in a liquid form to melt the ice. To get this to stick to the road so it can melt the ice, they spray it on with sorghum. Sorghum is a grain, similar to wheat. It is drought tolerant and was grown in ancient times in Egypt. Current uses include cereal and animal feed in the United States. In other places it is used to brew beer. For our purposes it makes a very sticky molasses. It is in the molasses form we see it blended with magnesium chloride to aid in ice melt and snow removal. When this goop is kicked up off the road by the tires it sticks to the vehicle’s undercarriage and side panels and is then washed into the car wash reclaim tanks. We have seen this cause solenoid valves to become stuck in the open position in some cases. Occasionally running fresh water through those valves is one way to solve this problem.
Less common issues with yucky stuff in reclaim systems are often chemistry related. Chemicals react with each other sometimes positively. In a process we developed along with a chemical manufacturer, for instance, we use a hydrogen peroxide injection system in conjunction with ozone for water clarity and odor
Ozone and peroxide enhance each other to do a better job than they would do separately.
control. The ozone and peroxide enhance each other to do a better job than they would do separately. In vehicle washing, MSOs (mineral seal oils), found in some finish waxes and drying agents, will allow a buildup to occur that is usually visible on the strainer basket of the reclaim system. The pictures on pages 18 and 22 are extreme examples of what that looks like.
Another yucky stuff chemical example is pH balance. Neutral is 7 to 7.4 on the pH scale. Most municipalities want the pH of discharge between 5 and 9. Sometimes it may be too far to the low, acidic side of the pH scale and get a powerful stench out of the reclaim water. This is often true if the acid being used has a high sulfuric content. I have heard the smell described as rotten eggs or, in the extreme, compared to a tire fire.
We’ve touched on some examples of things that can create issues with your reclaim system’s water. This is by no means a comprehensive list. As with most things, I could go on and on and on. If you are having issues with your reclaim system’s water, whether clean ability, odor, sticky valves, or even all three, contact your car wash equipment supplier and start talking about it. If they are any good, and they can’t answer your questions, they will know whom to ask.
Charles Borchard is the vice president of operations for New Wave Industries, the manufacturer of PurClean Spot-free Rinse Systems and PurWater Water Recovery Systems. He is in his 28th year in the water treatment business. He can be reached via email: email@example.com if you have questions about this article.