[Purification of dichloromethane waste gas in a biotrickling filter].

An experimental investigation on purification of dichloromethane waste gas was conducted in a 50 mm diameter biotrickling filter packed with randomly-stacked polypropylene. A heterotrophic population was acclimated from facility's secondary sludge, and was further inoculated over the surface of the packing. The inoculation process lasted about 30 days, and then a biofilm was developed. The counter-current operation was carried out in the filter. The pH and temperature of the circulating liquid were controlled as 7.0 +/- 0.5 and 28.5 +/- 2 degrees C respectively. The biofilm system was well accommodative to the fluctuation of operating conditions. When the concentration of dichloromethane was in the range of 0.7 to 3.12 g/m3, and the gas empty-bed residence time was 15.7 s, the removal efficiency of 72.0 to 99.1% could be achieved. It was also showed that the acid environment in the filter could refrain the degradation of dichloromethane.