Photoassisted Biodegradation of Irradiated Organics in Simulated Nuclear Wastewater

The extent of dehalogenation and degradation of toxic aromatic compounds in a nuclear wastewater was evaluated using a two-stage system consisting of a photolytic reactor followed by a biological reactor. Experiments were performed by varying the initial 4-chlorophenol (4-CP) concentration from 50 to 1000 mg/L. The UV pretreatment stage improved the overall efficiency of biodegradation of the recalcitrant compound by facilitating degradability in the biological stage. Removal efficiencies greater than 98% were achieved at 4-CP feed concentrations < 50 mg/L. Adding an H2O2 dose of 0.1 mg/L as an oxidant further improved biodegradation under optimum operating conditions for the entire system. Some known aromatic compound degraders such as Pseudomonas aeruginosa and Pseudomonas mendocina were detected in the consortium using the 16S rRNA genetic fingerprint technique. To the authors' knowledge, this is the first study on biodegradation of halogenated aromatic compounds that are copollutants of metallic radionuclides in radioactive wastewater.