The main concerns in using reclaim water are that it smells, it makes the equipment dirty, and it leaves a film on the car. As Charles Borchard discussed in his article in the March 2018 issue of Auto Laundry News, the culprit in any one of the concerns stated above cannot be easily blamed on one specific thing. You must be willing to go through the process to find out the breakdown in your system as a whole. What you introduce into the water, how you treat the water, and your plumbing, must all combine and work together to give you the outcome you are looking for. Notwithstanding the importance of the rest of the reclaim process as a whole, in this article I would like to focus on the various processes that reclaim manufacturers use to treat car wash water, and how they react with various chemicals.
The purpose of a reclaim system, regardless of the size or industry, is to reuse as much water as possible. Reusing water, however, is a complicated business that requires a constant review and evaluation of best approaches and processes to employ efficient and cost effective means. In this day and age, we all are interested in the environmental impact and footprint our practices make, and wiser, more environmentally friendly treatments are being embraced.
Reclaim pits are designed to provide a containment system that promotes a suitable environment for solid settling. The cleaner the water is the less of an impact is felt throughout the system — everything from cleaner filters, spray nozzles, rinse water, and, of course, odor control. Cleaner wash water also plays an important role in pit pump-outs because many states consider the wastewater to be hazardous or, at the very least, contaminated.
There are several ways to approach treating reclaim water for odor control and removal of oil and greases that help to cause the odors and increase pump-out of reclaim reservoirs. Let’s take a look at a few of the most used methods in the industry.
Aeration provides oxygen to bacteria for treating and stabilizing the wastewater. Oxygen is needed by the bacteria to allow biodegradation to occur. Bacteria in the wastewater utilize the supplied oxygen to break down the organic-matter-containing carbon to form carbon dioxide and water. Without the presence of sufficient oxygen, bacteria are not able to biodegrade the incoming organic matter in a reasonable time. In the absence of dissolved oxygen, degradation must occur under septic conditions, which are slow, odorous, and yield incomplete conversions of pollutants. Under septic conditions, some of the biological processes convert hydrogen and sulfur to form hydrogen sulfide and transform carbon into methane. Other carbon will be converted to organic acids that create low pH conditions in the basin and make the water more difficult to treat and promote odor formation. Biodegradation of organic matter in the absence of oxygen is a very slow biological process.
Aeration of the reclaim reservoir is one of the ways to control odor and assist in the breakdown of most car wash chemicals. Aeration may raise the levels of dissolved oxygen enough to reduce or eliminate odors without further action. Oftentimes using an air purifier such as an AirSep unit to purify the oxygen being used in the aeration process will amplify the effect and also help to break down biodegradable chemicals at a faster rate. There are several ways to aerate the reclaim reservoir. Many use a venturi to draw in the ambient air or purified air into the circulating module of the reclaim system. This keeps the aerator above the ground for easier maintenance. Others may use an air pump or similar device to provide aeration. The benefit to aeration is simplicity and low maintenance for the end user. Cleaning the venturi and maintaining the air purifier would be the main task. The drawback to using aeration is that in warmer climates and where chemicals are over-used it may not be enough to completely keep the odor at bay.
A second way to reduce odor in reclaim tanks is the introduction of bacteria to the system. In addition to solids settling, the design of most reclaim pits promotes bacterial cleaning action. Bacteria can be designed to remove the oils and grease in the reclaim reservoir and hasten the biodegradable chemicals’ degradation. The removal of these items will go a long way in reducing odor.
The primary design of bacteria is to degrade various types of organic matter in a multiplicity of environments, including inside of humans! It is estimated that less than 5 percent of all forms of bacteria are pathogens (disease-causing) and that the other 95 percent are beneficial organisms just trying to make a living degrading whatever it is that they degrade best. For our purposes, we will be discussing environmental bacterial applications that target the waste components most readily found in commercial and industrial vehicle wash water.
Bacteria require very little to thrive in a wash-water environment and as a result of just a few specific parameters, they will provide a round-the-clock cleaning service that is second to none. So how does one find the right bacteria to help clean up vehicle wash water?
In the case of locating bacteria most suitable for cleaning up vehicle wash water, the important element is recognizing what the biggest contaminating constituents are of the water: petroleum hydrocarbons, various surfactant chemistries, and plain old dirt. Fortunately, there are perfected bacterial inoculants commercially available that have proven performance in various wastewater applications that target the degradation of petroleum chains, various surfactant concentrations, and organic matter. In addition, it would be really sweet if not only the water was cleaned up but the air too. Hydrogen sulfide odor is the prevalent in-your-face issue for most commercial and industrial wash applications. The right bacteria species can eliminate hydrogen sulfide odor within 24 to 48 hours after application.
The microbiology of a wash system is simple: dirty water has bacterial loads that come with the territory. The critical component here is that the indigenous bacteria (that’s the bacteria that ends up in a wash water stream by default, coming in with the dirt) is a hodgepodge of various types of colonies that almost always fail to provide any significant advantage; in fact, the result of the incomplete degradation of petroleum, dirt, surfactants, and other water contaminates is what causes the hydrogen sulfide odor in the first place. Some bacteria are designed by nature to utilizeall the carbon chains in these waste products without producing a noxious by-product such as hydrogen sulfide. Inoculating with a beneficial, high population of bacteria allows for competitive exclusion, or in lay terms: “Let the best microbe win!”
Competitive exclusion specifically occurs when one species of bacteria significantly outnumbers the other species in their aggressive pursuit of a food source — in the case of wash water, most notably petroleum hydrocarbons. Bacteria do not require much besides a food source to thrive. They do need a dissolved oxygen rate of at least 1, although more is certainly good. They like a pH range of between 6 and 8, and they especially like as long a retention time as possible but will “eat and run” in as little as an eight-hour retention. Aeration in a system provides welcomed oxygen and agitation, which makes microbes flourish. The result: natural hydrogen sulfide odor control, significantly reduced TSS and BOD levels, and much cleaner recirculating water that extends filter life and reduces clogged nozzles. In such a system a biomass will develop within the reclaim tank. Biomass is an accumulation of microbes that colonize onto the hard surface of the tank. This cell accumulation produces billions of new microbes daily, keeping the system in good biological balance.
The last process we will explore is using ozone as a treatment for reclaim reservoirs. Ozone is a powerful oxidant(far more so than oxygen) and has many industrial applications related to oxidation. Ozone can be manufactured in several ways: cold fusion, corona discharge, and by UV. Cold fusion and corona discharge are the preferred methods for reclaim water since the amount produced is much greater than by UV light. The amount created by UV is quite small compared to the other two methods and is commonly used on clean water applications that do not require much ozone for success. Therefore cold fusion and corona discharge options are best suited for reclaim water applications.
When paired with an oxygen concentrator, cold fusion and corona discharge units can produce enough ozone to easily control most issues that a wash will encounter. Ozone is generated onsite by a generator paired with the above mentioned oxygen concentrator and delivered to the wash water by venturi or nanobubble diffuser. Since the water is constantly turned over on most reclaim systems, a smaller sized ozone generator is generally all that is needed to control the odor and remove unwanted dyes as well as other items from the reclaim stream.
Basically, ozone is radicalized oxygen; this means that it will revert to oxygen fairly quickly. It is much more powerful than chlorine and other oxidizers used in water remediation with the upside of leaving no residual to deal with. Ozone can remove the color associated with wash chemicals and kill bacteria on contact, thus helping to remove the odor associated with reclaim water. Ozone is also a micro flocculent: This means that it will bond smaller particles together allowing them to settle to the bottom of the tank system. Ozone will break down oils and greases allowing some settlement of these items in the reclaim tank.
We have discussed several methods that will help breakdown and/or remove petroleum hydrocarbons, various surfactants chemistries, and plain old dirt. However, over-introduction of silicone-based products, certain mineral seal oils, and outside influences can wreak havoc on the reclaim system no matter what treatment is being used.
Silicone tire shine, although very useful in the car wash, has no place in the reclaim pits. By it’s very nature, it will not biodegrade, settle out, or float to the top. This renders oil water separators and settling pits useless in controlling the issue. Over use or spills of high volumes of silicone-based products will cause slime balls to form within the pits that easily travel through the system no matter how much care is taken in treatment or settling. The slime balls will shatter when they hit most high-volume filtration devices and nozzles, then reform as a slimy film on the car, which is difficult to remove. Most operators combat this by diverting the flow of water from the tire shining directly to the sewer or using a water-based product that can be dealt with in the reclaim pits.
Certain mineral seal oils used in the car wash process will contain ammonia in order to keep algae from growing in the container during storage. Over usage of these beneficial products can disrupt the reclaim pits as well. The ammonia is highly detrimental to aerobic bacteria and can quickly turn reclaim pits towards a septic tank type system. More is not better when it comes to these products. Use as directed by the manufacturer and you should not have an issue.
Outside influences are often the culprit that can disrupt a reclaim system’s fragile balance. You can be treating the water with ozone made with oxygen, adding the latest designer aerobic bacteria, constantly recirculating your pits, your chemical introduction is right on spot, and all of a sudden you notice that the reclaim water smells. You are doing everything right, so what is happening? Most people don’t give it a second thought when they wash the parking lot into the pits, or clean the tunnel with straight acid or 14 pH cleaner. Most beneficial bacteria thrive in a 6-9 pH environment and none of them likes gasoline. You can wipe out a whole system in one night. Another, outside influence that can affect a reclaim system is well water. If not treated properly before use, well water can add salts, hydrogen sulfide, hardness, and sand to the reclaim pits. Well water is often to blame for reclaim water odor when it is coming from the freshwater rinse.
No matter your location there is a solution for you. Some areas of the world may be too hot for standalone aeration or too cold for living bacteria to thrive. Others may need a combination of the above-mentioned solutions to succeed. Generally, many start out with the option that seems best for their situation and then tweak the system to garner the results needed. We have found that ozone and bacteria are the two most popular methods in our industry, with many using both of them together to get the results required.
Dwight Royal is CEO, vice president of operations at Con-Serv Manufacturing. You can visit the company on the web at www.con-servwater.com.