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Antibiotics and nanoparticles, emerging contaminants, present great environmental risks and human health concerns. Sludge adsorption, a biological wastewater treatment removal mechanism, targets ciprofloxacin (Cip) antibiotics, C60, and ZnO, leaving complex pollution in sludge anaerobic digestion. This study investigated the mechanisms through which individual and combined ZnO, Cip, and C60 affect sludge anaerobic digestion by studying their effects on CH4 production, metabolism, and microbial community. ZnO was generally more toxic to CH4 production than Cip. The ZnO + Cip complex was more influential (>29%) than ZnO or ZnO + C60, with short-lasting acute and additive toxicity effects on methanogenesis and degradation of protein and carbohydrate. ZnO + C60 and ZnO + Cip exerted apparent additional complex effects on Firmicutes, Aminicenantes, Chloroflexi, and Parcubacteria. These results would potentially aid toxicity control related to complex pollution, and improve energy production and reduce pollution risks when used in land applications.

This work investigated the individual and combined effects of zinc oxide, norfloxacin, and sulfamethazine on sludge anaerobic digestion-associated methane production, protein and carbohydrate metabolism, and microbial diversity. Norfloxacin and sulfamethazine (500 mg/kg) did not inhibit methane production, but inhibited its production rate. Zinc oxide nanoparticles with antibiotics inhibited hydrolysis, fermentation, and methanogenesis over varying digestion periods. Complex pollution had a greater impact on methane production than zinc oxide alone, with acute, synergistic toxicity to methanogenesis over short periods. Complex pollution also had varying effects on bacterial and archaeal communities during digestion. These results aid understanding of the toxicity of emerging contaminants in sludge digestion, with the potential to improve pollution removal and reduce associated risks.

Antibiotics and nanoparticles, emerging contaminants, present great environmental risks and human health concerns. Sludge adsorption, a biological wastewater treatment removal mechanism, targets ciprofloxacin (Cip) antibiotics, C

The inhibitory effects and biotransformation potential of the fluoroquinolone antibiotic ciprofloxacin (CIP) under anoxic (i.e., nitrate reducing) and anaerobic (i.e., sulfate reducing and methanogenic) conditions were investigated. Fermentation and sulfate reduction was inhibited in 10-80 mg/L CIP-amended sulfate-reducing cultures but recovered with prolonged incubation. Methanogenesis in the mixed culture was significantly inhibited at 80-100 mg CIP/L. No significant decrease of CIP concentration was observed under both sulfate-reducing and methanogenic conditions. However, a low degree of CIP biotransformation was observed in a fed-batch denitrifying culture after a lag time even though the microbial, denitrifying activity was gradually inhibited at 24-40 mg CIP/L. Furthermore, the degradation of CIP was accelerated with a CIP reamendment of the denitrifying culture. Two CIP biotransformation products in the denitrifying culture were detected and their proposed chemical structures suggest that the antibiotic quinolone moiety of CIP was intact.

The adsorption, inhibition, and biotransformation of the fluoroquinolone antibiotic ciprofloxacin (CIP) under aerobic conditions were investigated in this study. The maximum adsorption capacity and the Langmuir constant were 37.9 mg CIP/g VSS and 37 L/g, respectively. A glucose-fed aerobic culture was inhibited by CIP at 10mg/L or higher and the degree of inhibition increased with increasing CIP concentration. However, the microbial activity recovered to some extent with prolonged incubation under a semi-continuous feeding mode. A low extent of CIP biotransformation was observed in an aerobic, glucose-fed culture derived from poultry litter extract. LC/UV/MS analysis of the biotransformation product showed that only the piperazine ring was oxidized, while the antibiotic quinolone part of CIP was intact.

The objective of this study was to investigate effects of different concentrations of tetracycline (TC) on the microbial community and development of tetracycline resistance genes (TRGs) of sequencing batch reactors (SBRs). Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) were used to detect the structural changes of the microbial community and the variations of eight TC resistance genes tet(A), tet(B), tet(C), tet(E), tet(M), tet(O), tet(S) and tet(X), respectively. The results indicated that, trace TC could substantially change the structure of the microbial community. Bacteria which could not adapt to environment with TC were gradually replaced by those adapting to tetracycline. Shannon's diversity index (H) and Simpson's index (D) reached maximum values when the concentration of TC was 1 μg L(-1). The resistance genes in the activated sludge proliferated under the pressure of trace TC.