Preventing a Toxic Chemical Disaster: RMPs in Theory and in Practice

For many years, dry chemical scrubbers have been considered as low maintenance alternatives to wet scrubbers in controlling a worst-case toxic gas release scenario such as a chlorine leak at a wastewater treatment plant (WWTP). When the U.S. Environmental Protection Agency mandated the development and implementation of risk management plans in the late 1990s, the use of dry emergency gas scrubbers (EGS) has increased and remains steady.The basic concept of an EGS is a packed-bed chemical reactor consisting of a media containment vessel, the dry-scrubbing media, and a blower. One type of medium in use against chlorine gas claims an improved performance both in terms of removal efficiency and capacity. Many systems have been installed in domestically and abroad specifically for the control of a catastrophic chlorine gas release.When one of these systems is placed at a WWTP with several tons of chlorine on-site, there can be no question as to whether the EGS will perform as designed should the need arise. These questions were answered when a potentially devastating chlorine release occurred at the Moccasin Bend WWTP (Chattanooga, TN) in 2009 and the 9-year old EGS neutralized all of the chlorine that had leaked from a one-ton cylinder.Theory and reality highlight the benefits of a properly designed, installed, and maintained EGS for toxic gas control. The dry-scrubbing medium used in this example has proved its use can effectively help to save the priceless elements of a community facing a potentially catastrophic toxic gas release