Improved nitrogen removal in dual-contaminated surface water by photocatalysis

Zhang, Yongming; Yan, Rong; Zou, Zhen; Wang, Jiewei; Rittmann, Bruce E.

doi:10.1007/s11783-012-0401-3

Cited by 5 publications

(2 citation statements)

References 26 publications

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“…Then, for the next seven days, the glucose concentration was decreased gradually from 300 mg/L to 0, while pyridine was increased gradually from 0 to 100 mg/L. Because pyridine and its derivatives are resistant to oxidation by dichromate in the COD assay, − we computed the theoretical chemical oxygen demand based on the following: C 5 H 5 N + 5.5O 2 + H + = 5CO 2 + H 2 O + NH 4 + . The computed chemical oxygen demand of the solution ranged from 321 mg/L (100% glucose) to 223 mg/L (100% pyridine).…”

Section: Methodsmentioning

confidence: 99%

“…Liquid samples were taken at time intervals to measure the concentrations of pyridine, NH 4 + , NO 3 – , and NO 2 – . For the B+S protocol, the concentrations of succinic acid added were the same as measured in experiments of pyridine UV photolysis of 2 h. Because pyridine and some aromatic products are not oxidized by dichromate in the COD assay, − we measured the loss of total organic carbon (TOC) to estimate the degree of pyridine mineralization.…”

Section: Methodsmentioning

confidence: 99%

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UV Photolysis for Accelerating Pyridine Biodegradation

Zhang

Chang

Yan

et al. 2013

Environ. Sci. Technol.

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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.

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