Metal Finishing Guide Book


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struction mode. Ozone is injected into this bed and the solvent is oxidized right on the carbon. No nitrogen oxides or carbon monoxide are formed in this process, and high destruction efficiencies are possible. Wet scrubbing can remove particulate as well as VOC. UV/OX systems are complicated, with many dampers, valves, and motors. Systems are large, and operating costs to produce ozone can be high. These systems have not been proven on very large airstreams. Another disadvantage is that a wastewater stream is produced. Biofiltration Biofiltration units have been successful in abating odors and some VOC streams. Large chambers charged with bacteria are used to convert VOC to carbon dioxide and other compounds. No nitrogen oxides are created with biofiltration and energy consumption is very low. However, bacteria need a relatively constant supply of solvents to remain active. Very large amounts of space are required and very little past experience in paint applications is available. CONCLUSION Applying the Right Solution It is quite clear that no one solution can be applied universally to all VOC abatement scenarios. The ideology of ���One Size Fits All��� is false and potentially costly. In choosing the right technology, it is important to examine both the process and the airstream constituents to be abated. A careful review of current and future regulations, along with local site considerations, i.e. utility costs, space constraints and local regulations should be used to select the appropriate solution to the end user���s problem. For paint/coating operations, effectively meeting today���s stricter VOC regulations is an ongoing challenge. For larger operations, meeting the challenge becomes a matter of improving overall system efficiencies and economics while retaining enough flexibility to adapt to new coating formulations. For smaller, previously unaffected operations, the challenge involves incorporating a new system into the overall operation and investing in new equipment. Careful consideration must be given to future growth and flexibility while working within the constraints of economic resource limitations. A well-planned environmental system can save many thousands of dollars, which can make a big difference to finishers trying to operate in a competitive industry. 700

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