Presidential Green Chemistry Challenge: 2008 Greener Reaction Conditions Award
3D TRASAR® Technology
Innovation and Benefits: Cooling water touches many facets of human life, including cooling for comfort in commercial buildings and cooling industrial processes. Cooling systems require added chemicals to control microbial growth, mineral deposits, and corrosion. Nalco developed 3D TRASAR® technology to monitor the condition of cooling water continuously and add appropriate chemicals only when needed, rather than on a fixed schedule. The technique saves water and energy, minimizes the use of water-treatment chemicals, and decreases environmental damage from discharged water.
Summary of Technology: Most commercial buildings, including offices, universities, hospitals, and stores, as well as many industrial processes, use cooling systems based on water. These cooling systems can consume vast quantities of water. Also, unless mineral scale and microbes are well-controlled, several problems can arise leading to increased water and energy consumption and negative environmental impacts.
Mineral scale, which consists mostly of carbonates of calcium and magnesium, forms on heat-exchange surfaces; this makes heat transfer inefficient and increases energy use. Similarly, microbial growth can lead to the formation of biofilms on heat-exchange surfaces, decreasing exchange efficiency. Conversely, high levels of biocide intended to prevent biofilm cause several adverse effects including increased corrosion of system components. Gradually, the integrity of the system becomes compromised, increasing the risk of system leaks. The material from these leaks, along with metal-containing byproducts of corrosion and the additional biocide, are ultimately discharged with the cooling water. Every time water is discharged, called "blowdown", pollutants are released in the wastewater, and fresh water is used to replace the blowdown. Traditionally, anti-scalants and antimicrobials are added at regular intervals or, at best, after manual or indirect measurements show scale or microbial buildup.
In 2004, Nalco commercialized its 3D TRASAR® Cooling System Chemistry and Control technology. By detecting scaling tendency early, cooling systems with Nalco's technology can operate efficiently; in addition, they can use less water or use poor-quality water.
3D Scale Control, part of the 3D TRASAR® system, prevents the formation of mineral scale on surfaces, maintaining efficient heat transfer. The system monitors antiscalant levels using a fluorescent-tagged, scale-dispersant polymer and responds quickly when conditions favor scale formation. In addition, 3D Bio-control, also part of the 3D TRASAR® system, is the only online, real-time test for measuring planktonic and sessile bacteria. It uses resazurin, another fluorescent molecule, which changes its fluorescent signature when it interacts with respiring microbes. By adding an oxidizing biocide in response to microbial activity, 3D Bio-control generally reduces the use of biocide and also prevents biofilm from building up on surfaces, maintaining efficient heat transfer.
A proprietary corrosion monitor and a novel corrosion inhibitor, phosphino succinic oligomer, provide improved corrosion protection. In 2006, the 2,500 installations using the 3D TRASAR® system saved approximately 21 billion gallons of water. These installations have also significantly reduced the discharge of water-treatment chemicals to water-treatment plants or natural waterways.