CHOOSING AN ODOR CONTROL TECHNOLOGY – EFFECTIVENESS AND COST CONSIDERATIONS

When decisions are made on an odor control technology, there are always two determinants that go into the final decision: odor removal effectiveness and cost. The former is one way manufacturers generate interest in their products. However, it still comes down to cost as to whether a specific technology or product is ultimately approved or rejected. Equal emphasis should be placed on both. While cost is very important, minimum performance criteria should be established. If a system costs less but offers a lower performance as well, it may or may not be cost efficient to save money on the front end. Cost evaluations are performed here to show a method of comparing technologies. Then an example scenario in which the criterion was to remove odorous gases below odor thresholds is presented to show a successful application of technology.Various odor control systems are cost effective at different air flows and different concentration levels. This paper presents advantages and disadvantages of five odor control technologies (wet scrubbers, biofilters, engineered media, granular activated carbon (GAC), and catalytic/regenerative carbon). Wet scrubbers have been shown to be an effective choice in high air velocity and flow applications. Dry-scrubbing technologies (engineered media, GAC, and catalytic/regenerative carbon) can be very effective at lower air velocities and have the ability to remove contaminant gases with high efficiencies. Biofilters have been shown to be effective at lower air velocity regions with the ability to have long media life.Cost comparison can be presented in several different ways. Cash Flow Analysis is proposed for determining which technology is the most cost effective. This type of analysis allows the end user to determine the actual cost of a system as a function of time. A comparison of the different technologies by initial cost, utility/maintenance cost, and accumulated cost, allows the customer to make a sound economic decision based upon his present needs and budgetary constraints. The contaminant most frequently cited in odor control applications is hydrogen sulfide and it is used for the Cash Flow Analysis in this paper. Two cash flow analyses were performed, a biofiltration application as a calculation example and a dry-scrubbing application as a comparison of two technologies. The biofiltration analysis showed a low maintenance cost for the system in terms of media replacement. The dry-scrubbing analysis determined engineered media to be more economical than catalytic/regenerative carbon in terms of initial investment and future cost for anywhere from 15 to 27 years. The catalytic/regenerative carbon showed less maintenance cost in terms of media replacement.