NATIONAL REPORT—Water treatment for systems such as cooling towers, chillers, heat exchangers and evaporative condensers has traditionally been one that has required the use of hazardous chemicals—e.g. chlorine, bromine, isothiazolinone, molybdate, phosphonate—to control calcium, bacteria, algae, scale, corrosion and biofilm. Because of the toxicity of the water treated with chemicals, it cannot be reused on property. A number of suppliers, however, have developed chemical free or similarly safe treatment systems that allow for the reuse of blow-down water while still providing a means to keep systems clean and running efficiently. Chemical free treatments vary from the introduction of atomic oxygen into the water to the application of an electronic field around piping. This article will examine some of the safer treatment systems on the market and provide real-use examples when possible.
Silver Bullet Water Treatment Co., LLC offers a patented technology that creates hydroxyl radicals (a natural non-toxic biocide) when injected into water, killing all bacteria, removing scale and preventing corrosion. Inside the Silver Bullet Water Treatment system, air from the surrounding environment is pulled into the Silver Bullet processor sleeves using pumps. The air passes through the sleeves, which contain UV lamps and patented components which create a gas that is bubbled into the cooling tower’s water supply. Water never passes through the Silver Bullet Water Treatment system.
Silver Bullet Water Treatment’s patented Advanced Oxidation Process (AOP) technology generates highly reactive hydroxyl and oxygen-free radicals. The hydroxyls and oxygen radicals oxidize contaminants in the water and kill bacteria, including Legionella, the cause of Legionnaire’s disease. Some of the remaining oxygen atoms combine with H2O to make H2O2, or hydrogen peroxide, which acts as a lasting biocide killing bacteria throughout the system. Other remaining oxygen atoms keep minerals such as calcium in solution, which prevents scaling. For calcium stuck on walls and surfaces, the reactive oxygen atoms break down the buildup so the calcium chips away and remains in the water. The Silver Bullet technology cuts water usage by increasing cycles of concentration, cuts electricity by removing scale and eliminates the need for toxic chemical delivery, storage and removal.
D.C. Hotel Saves Big with Silver Bullet System
Almost two years ago, a Silver Bullet system was installed at the Willard InterContinental Hotel in Washington, D.C. In the first 10 months of operation, the Willard was able to save over 500,000 gallons of water and over 30,000 kWh of electricity. The Willard also saw savings through reduced labor and maintenance time for the building’s HVAC system.
“Our system is designed to be used by a professional water treater,” says Murray Smith, Chief Sales & Marketing Officer for Silver Bullet Water Treatment Co. “We have priced our system to be equivalent to the cost of chemicals process. We are either at the same cost or less. We rent our system on a monthly basis. The end user gets to keep the water and energy savings. In many cases municipalities will provide credits. There is no big upfront capital.”
Conservation Solutions Corp. offers a FlowMark System that uses a pulse electronic frequency that changes the structure of the water. Nothing is introduced into the water; the FlowMark System simply wraps around chilled water piping or water supply piping and then is plugged in. How much pipe needs to be wrapped depends on the size of the pipe. There is no need to cut pipe or shut down the system to get started. FlowMark technology prevents scale buildup by neutralizing the natural charge that suspended solids carry which in turn makes the suspended solids the preferred location for scale to form. The FlowMark System helps restore heat transfer efficiency and lowers maintenance and energy costs. The need for some corrosion prohibitors is eliminated.
“We do a number of things that accomplish what chemicals would do,” says Dan Cook, President, Conservation Solutions. “We are getting energy savings by eliminating biofilm and calcium scale. Legionella and biofilm concern is eliminated. We lower the amount of particulates in the water. We can save a lot of water if it is hard water and a significant amount if it is soft water.”
Comfort Inn & Suites Benefiting from FlowMark System
The Comfort Inn & Suites Boston Logan International Airport has installed a FlowMark System for its cooling tower and heat exchanger. The FlowMark System, installed by Conservation Solutions, has sharply cut water use and eliminated the need for hazardous chemicals to control calcium, bacteria, scale, corrosion and biofilm.
The Comfort Inn’s new system cost $6,300 to install and saves the hotel roughly $5,685 in water and sewer, chemical, electricity and maintenance costs per year. The ROI is just 1.1 years.
“The larger the system, the quicker the payback,” Cook says. “We have some hotels in Florida where we are using some ozone systems in conjunction with Flowmark pulse technology. The ozone eliminates bacteria and algae.”
Scale Free Systems also offers a solution that halts corrosion, prevents and reverses the formation of scale, and controls biological growth without the use of chemicals.
“We do not try to change water chemistry at all,” says Bon Hanneken, Vice President and part owner, Scale Free Systems. “We protect the equipment from the water. We have control systems that monitor electrical activity in the water. Water goes through the control panel. We modulate the equipment. We bring the polarity of the equipment close to the polarity of the water. The materials in the water are positively charged. They want to attach to anything that has a negative charge. We bring that environment to a more neutral environment. We can usually cycle the water more times. We can save the customer water in and water out. The blow-down water can be used on-site.”
“The amount of electrical activity happening in the water is at a very low amount,” Hanneken adds. “You are not actually charging the equipment. There is a sacrificial anode in the water. We are providing a better path to ground for those mineral ions. We are providing a linear current for that electrical activity to go to ground through the anode.”
Electric Fields Control Corrosion, Scaling
Evapco, Inc. offers a non-chemical water treatment system called Pulse~Pure that utilizes electric fields to control corrosion, scaling and micro-biological growth. Pulse~Pure technology creates “seed crystals” from small suspended particles in circulating cooling water. As the Pulse~Pure treated water is cycled up beyond normal solubility, the calcium carbonate precipitates onto the seed crystals eventually settling out in the basin of the evaporative equipment as non-adherent powder. The result is clean heat transfer surfaces coupled with clear basin water.
Pulse~Pure technology controls biological growth by two physical mechanisms; agglomeration and electroporation. Agglomeration is the mechanism where seed crystals form with calcium carbonate and trap bacteria and other small particles in the growing matrix. Electroporation is the process of damage to the bacteria’s cell wall caused by the pulsed electric fields generated in the Pulse~Pure chamber.
Pulse~Pure technology controls corrosion by operating in an alkaline environment beyond the normal saturation for calcium carbonate. These operating characteristics allow calcium carbonate to act as a natural cathodic corrosion inhibitor. Corrosion potential is reduced further by the elimination of the need for feeding corrosive oxidizing biocides and other potentially harmful chemicals.
Trident System Incorporates UV Sterilization
The Trident Systems Non-Chemical Water Treatment System is a non-chemical solution for controlling scale, corrosion and bacteria. One pillar of the system is the Ecoflow Catalytic Water Conditioner. It works efficiently to create calcium carbonate crystals. The precipitation of these calcium carbonate crystals are the key to successful and consistent non-chemical scale control. The Harmsco Hurricane filtration is the second pillar of the system. The third pillar is UV sterilization which is industry proven to control bacteria.
Clearwater Systems’ Dolphin WaterCare approach toward water treatment is chemical free. The Dolphin system leverages pulse-power technology to impart a broad spectrum of electro-magnetic fields into the flowing cooling tower water. This removes the static charge from naturally-occurring particles and results in scale prevention. With the static charge removed the particles then become the preferred surface for minerals to precipitate around rather than forming scale on the surfaces of the cooling tower and HVAC equipment. The system operates in a saturated environment which is naturally non-corrosive. Additionally, there is no risk of chemical corrosion. Biological control is achieved through encapsulation and electroporation. Dolphin treated water typically has even lower biological counts than the accepted standards for drinking water.
Water treatment systems that are free of chemicals can qualify one for LEED points if one is pursuing LEED certification.
Glenn Hasek can be reached at firstname.lastname@example.org.