Performance of a Full-Scale Biotrickling Filter Treating H_2S at a Gas Contact Time of 1.6 to 2.2 Seconds

摘要

Emission of objectionable odors is a major problem for wastewater treatment and other processing facilities. Biological treatment is a promising alternative to conventional control methods, such as chemical scrubbing, but historically, biotreatment has always required significantly larger reactor volumes than chemical scrubbers. In this paper, we present several aspects of the operation and performance of a chemical scrubber, retrofitted to operate as a biotrickling filter treating 16,000 m~3 h~(-1) of foul air with the original gas contact time of 1.6 to 2.2 seconds. In continuous operation for more than a year, the biotrickling filter has shown stable, performance and robust behavior for H_2S treatment, with pollutant removal performance comparable to using a chemical scrubber. Reclaimed water was used as a nutrient source for the process, and to maintain the pH in the biotrickling filter between 1.5 and 2.2, At a gas contact time of 1.6 seconds, H_2S removal was in excess of 95% for sustained inlet H_2S concentrations as high as 30 ppm_v. This corresponds to volumetric elimination rates of 95 to 105g H_2S m~(-3) h~(-1). Efficiencies of about 90% were observed under transient conditions at 2.2 seconds gas contact time for inlet concentration peaks up to 60 ppm_v. The biotrickling filter also removed significant amounts of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air, which is important in practical applications. Selected experiments, such as intermittent trickling operation and a one-month operation period at neutralpH, are also presented. Results indicate that the intermittent trickling operation does not have a significant effect on H_2S removal. However, when operated at neutral pH, biotrickling filter performance clearly decreased, probably due to an excessive chlorine supply to the reactor through the make-up water. The study demonstrates that biotrickling filters can replace chemical scrubbers as a safer, more economical technique for odor control.