A one-step technological system containing activated sludge fed with synthetic domestic wastewater was applied to treat waste air polluted with tetrachloroethene (PCE). In the first stage of the experiment, air passed through a bioscrubber; in the second and third stages, it passed through the bioreactor containing activated sludge and bacteria immobilised in oak chips. These bacteria are active in PCE biodegradation. Process efficiency in the final stage of the experiment was high; the elimination capacity was 0.23 g m⁻³ h⁻¹ with the PCE mass loading rate of 0.58 g m⁻³ h⁻¹. It has been shown that in the activated sludge bioreactor, bacteria adapted to PCE biodegradation and the wood chips protected microorganisms from the toxic effects of pollution. The dominant strains of bacteria immobilised in wood chips have been identified. Most of them were Gram-negative rods – Pseudomonas aeruginosa, Pseudomonas putida, Ralstonia pickettii and Ochrobactrum anthropii. Only one strain was Gram-positive and of cylindrical shape. The results of the study indicate the potential of immobilised bacteria capable of degrading chlorinated aliphatic hydrocarbons for the air and wastewater treatment. The low cost of the treatment process is an advantage.

A laboratory scale sequencing batch reactor (SBR), fed with synthetic wastewater containing a mixture of organic compounds, was operated for nearly six months. Despite maintaining the same operational conditions, a deterioration of enhanced biological phosphorus removal (EBPR) occurred after 40 days of SBR operation. The P_rel/C_upt ratio decreased from 0.28 to 0.06 P-mol C-mol⁻¹, and C requirements increased from 11 to 32 mg C h⁻¹ g⁻¹ of mixed liquor suspended solids. A FISH analysis showed that the percentage of Accumulibacter in an overall community of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) dropped from 93% to 13%. An increase in abundance of Gammaproteobacteria (from 2.6% to 22%) and Alphaproteobacteria (from 1.8% to 10%) was observed. The number of Competibacter increased from 0.5% to nearly 9%. Clusters 1 and 2 of Defluviicoccus-related GAOs, not detected before deterioration, constituted 35% and 27% of Alphaproteobacteria, respectively. We concluded that lab-scale experiments should not be extended implicitly to full-scale EBPR systems because some bacterial groups are detected mainlyin lab-scale reactors. Well-defined, lab-scale operational conditions reduce the number of ecological niches available to bacteria.