|HOME SCHEDULE AUTHOR INDEX SUBJECT INDEX|
PT04 Water Quality Monitoring
(PT063) Evaluation of risk and treatment options for hydrazine in effluents from CANDU Generating Stations.
Rodgers, D1, Dias, S1, Massey, R1, 1 Kinectrics, Toronto, ON, Canada
ABSTRACT- Hydrazine (NH2-NH2) is used as an oxygen scavenger to maintain low oxygen concentrations in boiler feed and lay-up waters in many nuclear and fossil thermal generating stations. Consequently, N2H4 may be present in effluents from boiler feed water, boiler blow-down and lay-up water. In aquatic effluents, N2H4 is a significant factor in the toxicity of some effluents, with LC50 values in the order of 0.5 mg/L (initial concentration) in Daphnia magna acute (48 h) toxicity tests. We surveyed Ontario CANDU stations to identify all station uses of N2H4; the media (air, water) to which releases occur; and to quantify concentrations and loadings of N2H4 associated with these releases. We summarized available scientific literature to characterize the environmental chemistry and fate of N2H4 under relevant conditions with particular regard to the influence of water chemistry, and to identify potentially significant reaction products and interactions with other contaminants. We applied this information to assess the environmental risk from operational release of N2H4 and to identify situations where treatment may be required before release. In continuing investigations of practical methods of N2H4 oxidation, we are examining the application of elevated temperatures and metal catalyzed hydrogen peroxide oxidation to facilitate N2H4 oxidation and the confounding effects of ammonia and morpholine.
Key words: Oxygen scavenger, Hydrazine, aquatic toxicity, oxidation
Internet Services provided by|
Allen Press, Inc. | 810 E. 10th St. | Lawrence, Kansas 66044 USA
e-mail firstname.lastname@example.org | Web www.allenpress.com
All content is Copyright © 2003 SETAC