Pulseback of panel bed contactor for carbon and water

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Virginia Polytechnic Institute and State University


A method for removing chemical contaminants, such as phenol, from a stream of waste water has been proposed. The method uses a device for contacting water with activated carbon, called a "panel bed". In this device, water flows across a bed of activated carbon retained within a set of parallel louvers. Construction permits contaminants in the entering stream of water to be adsorbed on carbon particles, starting from the entrances of the spaces between the louvers. A pulseback technique is used to remove the region containing "contaminated" activated carbon. Pulseback is applied periodically after appropriate intervals of operation. This research aims to determine operating characteristics of a panel bed and focuses on the study of pulseback.

From a previous design of a panel bed filter for removing fly ash from stack gases, and from a basic study of characteristics of activated carbon adsorption isotherms, a panel bed was constructed which was believed to be suitable for contacting activated carbon with waste water.

Pulseback consists of a reverse transient flow of water across the panel bed of activated carbon. Detailed descriptions of pulseback equipment, data on the spill of carbon that accompanies pulseback, and correlation of the carbon spill data are included. The carbon spill during pulseback appears to correlate with "active time", where this term refers to the time during which a reverse pressure difference, created by the reverse transient flow of water, exceeds a critical minimum value necessary for any spill at all to occur. For the specific design of equipment used in this study, the spill is relatively small if the active time is less than 60 milliseconds. Beyond 60 milliseconds, for the specific equipment used, the spill is linear with active time, and occurs at a rate that appears related to Zenz's modification of the Francis weir formula to describe efflux of solids from a static bed through an opening.