Inhibitory impact of the anticancer drug doxorubicin on anaerobic microbial community

•Doxorubicin can hinder biogas production rate.•The inhibition caused by doxorubicin was reversible.•Rapid drug sorption into the biomass was observed despite the low Kow value.•Methanosaeta and Methanobacterium were the most abundant archaeas in long-term exposure to doxorubicin. The inhibitory effect of the anticancer drug doxorubicin (DOX) on biogas production was evaluated in short-term and long-term exposure assays. The short-term assays reached the DOX IC50 value on 648 ± 50 µg·L−1. In addition, it was found that inhibition caused by the exposure of 10×103 µg·L−1 was reversible after removing DOX from the feeding synthetic medium. Furthermore, DOX can be rapidly sorbed by the biomass (despite the low Kow), which might contribute to the inhibitory effect. The results of long-term exposure assays, when the DOX volumetric loading rate was increased from 100 µgDOX·L−1·day−1 to 200 µgDOX·L−1·day−1, showed that biogas production and COD removal decreased rapidly. However, the methanogenic Archaeas could recover from this exposure, corroborating the results on short-term exposure assays. In conclusion, DOX can play a key role in inhibiting biological wastewater treatment processes if its concentration in hospital wastewater treatment plants increases abruptly. [Display omitted]