UV Photolysis for Accelerating Pyridine Biodegradation

• Published in: Environmental science & technology 2014-01, Vol.48 (1), p.649-655
• Main Authors: Zhang, Yongming, Chang, Ling, Yan, Ning, Tang, Yingxia, Liu, Rui, Rittmann, Bruce E
• Format: Article
• Language: English
• Subjects: Acids; Analytical chemistry; Applied sciences; Biodegradation; Biodegradation, Environmental; Biofilms; Biological and medical sciences; Biological treatment of waters; Bioreactors; Biotechnology; Biotransformation; Circulation; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Kinetics; Mineralization; Organic chemicals; Oxidation; Oxidation-Reduction; Photolysis; Pollution; Pyridines - chemistry; Pyridines - isolation & purification; Pyridines - metabolism; Succinic Acid - chemistry; Succinic Acid - metabolism; Ultraviolet radiation; Ultraviolet Rays; Wastewaters; Water Pollutants, Chemical - isolation & purification; Water Pollutants, Chemical - metabolism; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es404399t

Pyridine, a nitrogen-containing heterocyclic compound, is slowly biodegradable, and coupling biodegradation with UV photolysis is a potential means to accelerate its biotransformation and mineralization. The initial steps of pyridine biodegradation involve mono-oxygenation reactions that have molecular oxygen and an intracellular electron carrier as cosubstrates. We employed an internal circulation baffled biofilm reactor for pyridine biodegradation following three protocols: direct biodegradation (B), biodegradation after photolysis (P+B), and biodegradation with succinic acid added (B+S). Succinic acid was the main UV-photolysis product from pyridine, and its catabolic oxidation generates internal electron carriers that may accelerate the initial steps of pyridine biodegradation. Compared with direct biodegradation of pyridine (B), the removal rate for the same concentration of photolyzed pyridine (P+B) was higher by 15 to 43%, depending on the initial pyridine concentrations (increasing through the range of 130 to 310 mg/L). Adding succinic acid alone (B+S) gave results similar to P+B, which supports that succinic acid was the main agent for accelerating the pyridine biodegradation rate. In addition, protocols P+B and B+S were similar in terms of increasing pyridine mineralization over 10 h: 84% and 87%, respectively, which were higher than with protocol B (72%). The positive impact of succinic acidwhether added directly or produced via UV photolysisconfirms that its catabolism, which produced intracellular electron carriers, accelerated the initial steps of pyridine biotransformation.