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Estrogen Nitration Kinetics and Implications for Wastewater Treatment
Author(s) -
Gaulke Linda S.,
Strand Stuart E.,
Kalhorn Thomas F.,
Stensel H David
Publication year - 2009
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143009x407285
Subject(s) - nitration , chemistry , nitrite , estrogen , environmental chemistry , wastewater , estrone , nitrosomonas europaea , sewage treatment , nitrate , biochemistry , organic chemistry , environmental engineering , medicine , hormone , environmental science
Understanding estrogen‐removal mechanisms in wastewater treatment is imperative, as estrogens have environmental effects at trace concentrations. Previous research investigating co‐metabolic degradation of 17α‐ethinylestradiol (EE2) by ammonia‐oxidizing bacteria (AOB) revealed that, in batch tests where high nitrite‐nitrogen (NO 2 ‐N) concentrations occurred as a result of ammonia‐nitrogen (NH 4 ‐N) oxidation by AOB, an abiotic estrogen nitration reaction actually was occurring—not co‐metabolic degradation. This paper addresses nitration kinetics. A first‐order abiotic nitration model was developed that predicts nitration of EE2, 17β‐estradiol (E2), and estrone (E1) as a function of temperature, pH, estrogen (EE2, E2, and E1), and NO 2 ‐N concentration. A contact time of 3.6 to 4.1 days is required for 90% estrogen nitration at 500 mg/L NO 2 ‐N and pH 6.4. At 20°C and pH 6.4, the threshold NO 2 ‐N concentration for nitration to occur is 9 mg/L; therefore, estrogen nitration is not likely in activated sludge treatment of domestic wastewater, but has potential for high‐NH 4 ‐N‐strength wastewaters.