Process for degradation of nitrobenzene: Combining electron beam irradiation with biotransformation

Electron beam irradiations of aqueous solutions containing 15–30 mg/L of nitrobenzene at 60 kGy dose removed 78% of the contaminant. Three mononitrophenols were detected as by‐products of electron beam treatment of nitrobenzene. A mixed culture enriched on a mixture of 2‐, 3‐, and 4‐nitrophenol degraded both the residual nitrobenzene and the nitrophenol products. Percentage removal of nitrobenzene increased with increasing electron beam dose. This observation led to the conceptual design of a two‐stage electron beam microbial process for degradation of nitrobenzene. Three groups of pure isolates were characterized from the mixed culture based on their abilities to grow on cor‐ responding nitrophenol substrates: Group A, 2NP−3NP−4NP+; Group B, 2NP+3NP+4NP−; and Group C, 2NP−3NP+4NP−. Bacteria that grew on 3‐NP transformed nitrobenzene into ammonia in the electron beam‐treated nitrobenzene samples. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 306–312, 2001.