اثر نرخ بارگذاري آلي بر پارامترهاي راهبري و ظرفيت بيوفيلتراسيون تولوين و زايلين از جريان گازهاي آلوده ي صنايع نفت و پتروشيمي

THE EFFECT OF ORGANIC LOADING RATE ON THE BIOLOGICAL REMOVAL OF TOLUENE AND XYLENE FROM CONTAMINATED GAS STREAMS

Biofiltration has proven to be an effective and economical technology to reduce VOC and other odiferous gases emitted from industrial sources. It provides significant advantages over conventional techniques such as absorption and adsorption for large air volumes of low gaseous pollutant concentrations. It is condsidered a clean technology with minimal energy requirements and low waste production. In this study, two labratory-scale biofilters were used for removal of toluene and xylene. The reactors were filled with a mixture of wood chips (0.5-2 cm) and municipal compost (80:20 vol.%) with a void space of 54%. The system was started and oprated under mesophilic conditions while keeping moisture content in the range of 60-70%. Overgrowth of microorganisms coupled with bed compaction reduced the void space resulting in increased pressure drop. To overcome these problems, the biofilter medium was emptied and mixed thoroughly and the system was restarted again. Under stready state conditions and at hydraulic residence time of 60 s, organic loading rate was gradually increased by increasing inlet concentration of pollutants. Results showed that at OLR values of up to 110 and 150 g m-3 h-1 for toluene and xylene, no signs of removal capacity limitations were observed. However, pressure drop considerations necessitated lower organic loading rates of 78±8 for toluene and 80±14 g m-3V-1 for xylene. Under these condition, it was possible to achieve elimination capacities of 73 ±4 g m-3h-1 and 73±14 g m-3h-1 and removal efficiencies of 94±6% and 91±8% for toluene and xylene, respectively.