Catalytic Nitrate Removal in a Trickle Bed Reactor: Direct Drinking Water Treatment


M. Bertoch, Bergquist, A. M., Gildert, G., Strathmann, T. J., and Werth, C. J., “Catalytic Nitrate Removal in a Trickle Bed Reactor: Direct Drinking Water Treatment,” Journal-American Water Works Association, vol. 109, no. 5, pp. E144, 2017.


Palladium (Pd)-based catalysts hold promise as an alternative water treatment technology for nitrate (NO3), but practical application requires a flow-through reactor that efficiently delivers hydrogen (H2) from gas to water. A trickle bed reactor (TBR) packed with a 0.1 percent by weight (wt%) Pd–0.01 wt% In/γ-Al2O3 (indium and porous aluminum oxide) catalyst was evaluated to address this challenge. Catalytic activity generally increased with H2 superficial velocity (0.65–29.6 m/h) and liquid (deionized water) superficial velocities from 14.8 to 26.6 m/h before decreasing at 38.5 m/h. This decrease corresponded to a change in flow regime and suggests that optimal TBR performance occurs at the transition from pulse to bubble flow. An optimal TBR activity of 19.5 ± 1.3 mg NO3/min-g Pd was obtained; this is only ~18% of the batch reactor activity as a result of H2 mass transfer limitations, but three to 15 times greater than activities obtained with previous flow-through reactors. Catalyst deactivation occurred in the TBR after 41 days of operation, motivating the need for improved fouling mitigation strategies.


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