No abstract

The whole bed height of a bio®lter was divided into four individual reactor stages in series. This con®guration permits a measurement of the leachate pH of each stage individually and minimizes interstage mixing of the immobilized culture. The extent to which the residence time of pollutant in the ®lter bed in¯uenced biodegradation characteristics and the composition of immobilized culture under conditions of a constant loading rate was studied using a perlite bio®lter having an internal diameter of 50 mm and the bed height of each stage being 27 cm. The residence time of pollutant in the bed had no in¯uence on the removal ef®ciency and the elimination capacity of the whole bio®lter although some changes of these parameters in the individual stages were observed. The bio®lter achieved an elimination capacity of 140 gm À3 h À1 at removal ef®ciencies greater than 90%. Degradation activity decreased the pH value of the leachate to 3.5±3.0. Microbial analyses showed that styrene was degraded by eukaryotic cells at low pH values. At pH values above 4.0 prokaryotes were also present in the mixed culture.

Styrene vapors from contaminated air were eliminated using long-term adapted mixed microbial culture inoculated on four perlite packed biofilters (serial arrangement, up-flow configuration). During start-up the inlet concentration of styrene rose from 175 to 1300 mg/m3 of total carbon. The total actual residence time in the four biofilters was 24 s. Styrene was successfully degraded by the microbial population in the biofilter. An average of 66% of eliminated styrene was transformed to CO2. The removal efficiency of the pollutant was, after 18 d of start-up, nearly 85% at an organic load of 170 g/m3 per h. The concentration profiles along the bed height were linear for various pollutant inlet concentrations. The total amount of microorganisms in analyzed biomass from the biofilters was about 10(9) per gram of dry packing mass. The moisture content was around 80% in all biofilters.

Methane combustion in the presence of various types of perovskites supported on ceramic foams has been studied with respect to the CO and NOx formation. The effect of the catalyst composition and of the air-to-methane ratio on the CO and NOx concentration has been evaluated for different burner capacities.

Catalytic combustion of methane has been studied in the presence of catalysts supported on ceramic foams. Low concentrations of NOx (in the range of 5 - 50 mg m-3) were observed with all catalysts used. Concentrations of CO depended strongly on the type of the catalyst, its composition, methane throughputs and varied from 4 400 to 0 mg m-3. Minimum CO concentration (0 - 8 mg m-3) was gained with 0.04% Pt on ceramic foam modified with both alumina Al2O3 and lanthana La2O3.