BIOTRICKLING FILTERS FOR POTWs AIR TREATMENT: FULL-SCALE EXPERIENCE WITH A CONVERTED SCRUBBER

Author： Gabriel David Cox Huub H. J. Brown Jeffrey Torres Edward Deshusses Marc A.

ISSN： 1938-6478

Source： Proceedings of the Water Environment Federation, Vol.2002, Iss.5, 2002-01, pp. : 657-669

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Abstract

The purpose of this work was to evaluate the technical feasibility of converting chemical scrubbers to biotrickling filters at a publicly owned treatment works (POTWs). A full-scale chemical scrubber (10,000 cfm) at Orange County Sanitation District (OCSD) was converted to a biotrickling filter after some research was previously conducted in a laboratory pilotscale biotrickling filter. The principal odorous compound targeted by OCSD was hydrogen sulfide. Removal of volatile organic compounds (VOCs) was also desired. The conversion only required replacing the packing medium and the recycle pump, and modifying the controls and operation of the bioreactor. The original TriPack packing was replaced with an open pore polyurethane foam and a 0.75 HP centrifugal pump was installed to replace the original 7.5 HP pump. Significant H₂S removal was measured 5 days after startup, and in 8 days, a quasi-steady state was achieved with very good removal of H₂S. Under the conditions at OCSD, i.e., a gas contact time of about 2 seconds, inlet averaged concentrations of 15 ppm and peaks up to 31 ppm of H₂S were degraded to less than 1 ppm, the discharge limit at OCSD according to the South Coast Air Quality Management District (SC-AQMD), just after biotrickling filter start-up. Long-term operation of the biotrickling filter also demonstrated its capability to treat higher inlet H₂S concentrations while keeping outlet H₂S concentrations below 1 ppm proving the ability of the biotrickling filter to handle highly variable loads. Some operational conditions of the biotrickling filter such as the response to a temporary pH increase and the response after a 48 hours starvation period are also discussed in the present paper. Based on the experimental portion of this project, very good removal of H₂S can be obtained in biotrickling filters operated at much higher gas velocities than is usually reported in the literature.