The Schwelvollert, a highly colored carbonization wastewater deposit located in Saxony-Anhalt (eastern Germany) was the subject of extensive analytical studies. When sampled in autumn the pyrolysis effluent lake was found to be stratified in three distinct layers, each exhibiting different physicochemical and microbiological characteristics. Although no oxygen was detectable in the whole deposit, aerobic bacteria were shown to predominate among pollutant degraders: in the upper layers about 40–60% degraders of phenolic compounds in heterotrophic microbial communities were found. Neither nitrate-reducers nor sulfate-reducing or methanogenic consortia that degraded benzoate were detectable. However, nitrite-reducing benzoate degraders were found with MPNs ranging from 0.03 to 20/mL. The attempt to identify aerobic isolates from the top layer with the commercially available BIOLOG and API 20NE identification systems revealed their unsuitability for the determination of specific pyrolysis effluent bacteria. Although the aerobic bacteria with specific degradation abilities are not likely to use their abilities under in-situ conditions, they represent a degradation potential which might be useful for aerobic remediation strategies.