Pollutant degradation in biotrickling filters for waste air treatment is generally thought to occur only in the biofilm. In two experiments with toluene degrading biotrickling filters, we show that suspended microorganisms in the recycle liquid may substantially contribute to the overall pollutant removal. Two days after reactor start up, the overall toluene elimination capacity reached a maximum of 125 g m(-3) h(-1), which was twice that found during prolonged operation. High biodegradation activity in the recycle liquid fully accounted for this short-term peak of pollutant elimination. During steady-state operation, the toluene degradation in the recycle liquid was 21% of the overall elimination capacity, although the amount of suspended biomass was only 1% of the amount of immobilized biomass. The results suggest that biotrickling filter performance may be improved by selecting operating conditions allowing for the development of an actively growing suspended culture.
New features and peculiarities of anomalous self-sustained Hall E × B discharge have been discovered. The presence of a minimum density of ions n upon the magnetic field induction B is confirmed for a wide range of discharge parameters. Likewise, the operation mode for a maximum density at the optimal values of the radial and longitudinal components of magnetic induction was discovered. Both effects are accompanied by the changes in the position of the combustion zone E × B of the discharge in the anode-cathode interval and the transformation of the distribution function of the ion energy. The threshold nature of the processes in the plasma E × B of the discharge can be manifested on the curves n = f(B) as an abrupt 3 to 4 times decrease in density upon the increase in B by not more than 10%. An abrupt increase in the density of ions (up to 16 times), occurring with a slight increase in the density of neutrals (∼1.2 times), is recorded when there are jumps of the anode layer from the anode region to the cathode one and vice versa. A thin structure of ion energy spectra explained by the isomagnetic potential jumps, which generate ion density jumps in a narrow energy range, was found. In the search for the reasons for the restructuring of the discharge and generation of isomagnetic jumps, the possible effect of nonlocal gradient-drift and electron-cyclotron drift instabilities on electron mobility and ion acceleration is briefly discussed.
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