Past Issue

Water - Reclamation and Rain Harvesting

By Tom Gibney

10/01/17

Why invest in a wastewater reclaim or restoration system?

Here is the primary reason: if your water and sewer rates continue to climb each year, they will erode your profits. With tax revenues down in most cities, local governments have discovered a cash cow in the city water and sewer departments. In some parts of the country the water and sewer rates are increasing annually by double digits and are projected to continue doing so for the next five years. If your wash is facing these cost increases, the best way to control the impact of these costs is by looking at a water reclaim or water restoration system for your wash.

If you have been trying to reduce your water-per-car usage by reducing nozzle sizes to cut costs, take a look at it from another direction.

By using a properly sized water restoration system you can use all the water you want to wash a vehicle since you will be cleaning that water and using it over and over again.

If you are using a spot-free-rinse system and letting the reject water go down the drain, capture that water in an aboveground tank the same size as the RO storage tank, and use that water to mix your chemicals. This way you generate some revenue from that water before it has a chance to goto sewer.

What about collecting rain water from the roof of your wash building? In most cases, if you are not surrounded by heavy industrial businesses, the rainwater will be clean and soft water.

In the vehicle wash industry there are three types of water treatment systems available. They are re-use, reclaim, and restoration.

RE-USE SYSTEM

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

RECLAIM SYSTEM

In a reclaim system the waste-water is sent through a series of settling tanks like the re-use system to settle out the heavy solids using gravity. When the water is pumped out of the last settling tank the water is processed through some form of filtration or cyclonic separation to further reduce the solids to micron level. This water is then treated with ozone, UV, zinc, or copper oxide to kill the natural bacteria in hopes that the water won’t smell when re-used. The water coming from a reclaim system still contains most of the chemicals used in previous washes. Used chemicals are not removed in a reclaim system so there are limitations as to where this water can be successfully re-used in the wa

Bio Media.

RESTORATION SYSTEM

A water restoration system utilizes the same settling tanks as the re-use and reclaim systems and, when the water is pumped from the last settling tank, it’s sent through hydro cyclones which cyclonically separate any remaining solids down to 5 micron. The wastewater is aerated, which creates an environment where aerobic bacteria are present. Aerobic bacteria are 90 percent more aggressive in consuming chemical waste in the water. When aerobic bacteria consume waste in the water they give off a CO2 gas, which 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 bacteria 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.

NATURAL RESTORATION

Nature has always been best at resolving pollution issues. Natural bacteria exist in every part of our environment. The EPA has been successfully cleaning up petroleum contamination by injecting bacteria into the soil to consume contamination. During the recent oil spill in the Gulf the natural bacteria in the seawater consumed the leftover oil that wasn’t collected.

Septic systems use anaerobic bacteria to break down human waste. At sewer treatment plants, aerobic bacteria are used along with high levels of oxygen to biodegrade and clean wastewater.

Anaerobic Bacteria

Anaerobic bacteria prefer to be in a dark environment that is void of oxygen in the water. If you think about the settling tanks in a car wash, they are dark and have little access to oxygen. Anaerobic bacteria thrive in used car wash water. Anaerobic bacteria give off a gas that smells like rotten eggs. These are the same bacteria that are present in home septic systems.

Aerobic Bacteria

Aerobic bacteria become active in water that has high levels of oxygen concentrated in the water. Aerobic bacteria that consume chemical waste in the water turn it into a CO2 gas, which has no smell.

Over the years different companies have tried to inject oxygen in the wastewater by using a small air pump or floating membrane. These types of systems simply cannot infuse enough oxygen in the water to maintain an environment where aerobic bacteria can survive. In an all-natural water restoration system, oxygenis supplied by an oxygen blower that delivers high volumes of oxygen under low pressure, which is dispensed through aeration membranes that dispense oxygen in small bubbles.

Aerobic bacteria are used to consume the used car wash chemicals in the wastewater as long as the chemicals are biodegradable and compatible. I’ll address biodegradability of chemicals in the “Biodegradable Chemicals” section.

For the bacteria to consume the chemicals, the bacteria must come in contact with the chemicals in the water. To achieve complete cleaning of the chemicals from the water, the bio chamber is filled with bio media where the bacteria can live. This dramatically increases the surface area in the tank so the bacteria can consume the waste chemicals.

BIODEGRADABLE CHEMICALS

Wastewater coming from a car wash contains chemicals that are made up 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. In the past, biodegradability wasn’t an issue as all the wastewater went to the sewer. Biological restoration makes it essential that chemical suppliers formulate for biodegradability and compatibility.

Biodegradability of chemical components is classified by three terms. The first classification is “readily” biodegradable. This means that the natural bacteria present in the water can easily biodegrade the chemicals and turn them into CO2  gas and water.

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

The last classification is “not” biodegradable. These chemical components cannot ever be used in a biologic treatment system. These are chemicals that will kill the bacteria.

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 bacteria. Anionic chemicals are not compatible with nonionic or cationic chemicals. When anionic chemicals are used, the resulting mixture is very difficult for natural bacteria to biodegrade.

RAIN HARVESTING

As previously stated, rainwater can be a good source of clean soft water that can be used in the wash to make spot-free rinse water or to mix chemicals. It can be used to flush toilets or water the landscape.

The formula for rain harvesting is: for every 1,000 square feet of surface area, one inch of rainfall will generate 750 gallons of water. The best place to find information about rainfall in your area is the website www.weatherbase.com.

Storm-water retention systems are something cities are asking landowners to install so that the storm sewers don’t get all the rainwater at once. If you are asked to install a storm-water retention system, turn it into a rainwater harvesting system and use the rainwater in your wash.

Water will always be the lifeblood of the vehicle wash industry. Management of water and sewer costs will ensure your wash will remain profitable for years to come.

 

Tom Gibney is president of Aqua Bio Technologies and has over 25 years of experience in the vehicle wash industry.
He formerly was the vice president of the industrial division of Turtle Wax.
You can contact Tom via e-mail at tgibney@aquabio.co or visit the company on the web at www.aquabio.co.

 

 



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