AbstractThe wastewater treatment plants (WWTPs) are the biggest reservoirs of pharmaceutical residues discharged into the environment. Among many pharmaceuticals, derivatives of 5-nitrofuran, whose cytotoxicity and neurotoxicity have been proved, are widely used. The ability of such compounds to accumulate in water and sediments motivated us to analyze the ability of microbial communities of rural and municipal WWTPs to eliminate nitrofurantoin (NFT), nitrofurazone (NFZ), furaltadone (FTD), and furazolidone (FZD). Metagenomic analysis of microbial communities in rural and municipal activated sludge has provided information about the bacterial biodiversity in the WWTPs. In both samples, the most dominant phylum in terms of abundance was Proteobacteria followed by Bacteroidetes; however, microbial community of the municipal WWTP exhibited greater biodiversity than the one of the rural WWTP. The results of high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis of the samples and elimination kinetic calculations allowed the determination of FZD, FTD, NFT, and NFZ elimination half-time varying from 104 to 327 h and test system first-order half-lives in the examined WWTP samples (from 31 to 231 h). Moreover, a comparison of the effectiveness of the microbials from two treatment plants, a rural one and a municipal one, revealed the poorer performance of the microbial communities from the smaller, rural WWTP in disposal of the analyzed pharmaceuticals, as after 24 days, the rural WWTP community was able to eliminate from 20 to 62% of 5-nitrofuran derivatives, while the municipal consortium removed over 85% of the compounds from the cultures.