Biological reduction and hydrodechlorination of chlorinated nitroaromatic antibiotic chloramphenicol under H2-transfer membrane biofilm reactor

•The interaction of nitrate and chloramphenicol (CAP) was investigated in H2-transfered membrane biofilm;•Nitro reduction and completely dechlorination of CAP were realized;•p-aminobenzoic acid was detected and a novel degradation pathway of CAP was proposed;•Pleomorphomonadaceae plays a role in dichlorination of CAP. Chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a persistent pollutant that is widely present in environments. A H2 transfer membrane biofilm reactor (H2-MBfR) and short-term batch tests were setup to investigate the co-removal of CAP and NO3-. Results showed that the presence of CAP (