Treatment of methanol in a dry biofilm reactor using tubular carrier

Abstract

A 13.4 l Dry Tubular Biofilm reactor (DTB), with 19 PVC tubes as carrier, was used to treat polluted air using methanol as a model pollutant. The design of this reactor was based on the creation of a mist by contacting the waste gas and a discontinuous liquid nutrient supply into an atomising nozzle. Air was fed into the reactor at specific gas flow rates from 60 to 230 m3/m3 · h, containing from 0.25 to 2.84×10-3 kg/m3 of methanol (volumetric loading rates from 1.4 to 4.7 kg/m3 · d). Biofilm growth was observed from the very beginning of the experiment although preferentially on the reactor's wall and not on the tubular carrier. Methanol degradation was observed to increase along the experiment and reached 1.24 kg/m3 · d. The efficiency of this system was limited by the clogging of the tubes used as carrier. The biofilm developed directly on the wall of the reactor had a specific methanol degradation rate of 1.08 kg/kgVSS · h, while only 0.6 kg/kgVSS · h of methanol were degraded after a long lag phase by the biomass developed inside the tubular carrier. Another experiment was carried out with the empty reactor without PVC tubing. In that case, a specific degradation rate of 4.15 kg/m3 · d was observed, which confirm that PVC tubular carrier was clearly not favourable to the process.