Thirty-five bacterial strains were isolated from wastewater sludge, with seven of the isolates belonging to risk group II and one to group I. The bacteria were identified to species based on the 16S rRNA sequence. Then, non-pathogenic strains (according to the DSMZ classification) were tested for the presence of enzymatic activities (amylase, lipase, protease, phytase, cellulolytic). Proceeding from the findings, two consortia for wastewater treatment were created from nine strains that were regarded promising: MG1 (based on four strains: Bacillus subtilis strain BAS21, Priestia megaterium strain BAS22, Pseudomonas baetica strain BAS23, Streptomyces albidoflavus strain BAS24) and MG2 (MG1consortium plus five thermotolerant strains: Bacillus subtilis strain BAS15, Bacillus licheniformis strain BAS16, Bacillus subtilis strain BAS17, Caldibacillus kokeshiiformis strain BAS18, Ureibacillus suwonensis strain BAS18). The new consortia were compared against the commercial Aquavicin-A product. In the control, the percentage of organic matter at the beginning was 13.21 % and remained practically unchanged by the end of the experiment – 13.05 %. The experimental treatments reduced this proportion. The best results were observed when using the MG1 consortium, where the organic matter content was reduced to 9.04 %; when adding Aquavicin-A and MG2, the reduction was insignificant (11.16 and 11.59 %, respectively). Two parameters of wastewater sludge – microbial numbers and the amount of organic matter – were significantly influenced by the MG1 consortium, which outperformed Aquavicin-A. The analysis of gases in sludge samples showed that the MG1 consortium, unlike the industrial product, completely removed ammonia, methylamine, and pyrrolidine. The findings indicate that the new consortia hold promise for wastewater sludge processing.