Retrofitting of an Industrial Chemical Scrubber into a Biotrickling Filter: Performance at a Gas Contact Time below 1s

The present work provides a description and an assessment of the conversion of an odor-treating industrial chemical scrubber into a biotrickling filter and of its startup and operation during 5months at an empty bed residence time of about 0.9s. The system treats a gas flow rate of around 50,000m3∕h, with average concentrations of volatile organic compounds, NH3 and H2S, of around 10, 2, and <1 ppmv, respectively. The main actions undertaken during the conversion were the substitution of the recirculation pump and of the packing material and the modification of the makeup water and purge flow controls. Afterwards, the reactor was inoculated with sludge obtained from a waste water treatment facility, and immediately started up as a biotrickling filter. No significant operation issues were observed during the operation period, other than pH variations and a slight increase in pressure drop, proving that the biotrickling filter is a highly robust system. Relatively low removal efficiencies around 10 and 25% were found, for the volatile organic compounds and NH3, respectively. However, due to the low empty bed residence time, these corresponded to notable elimination capacities of around 18gC∕m3h and 3gN∕m3h. No nutrients were supplied to the bioreactor during the first 5months of operation other than those contained in the sludge employed as inoculum.