Fish larval deformity caused by aldehydes and unknown byproducts in ozonated effluents from municipal wastewater
Zhiming Yan1, Yu Zhang1, Hongying Yuan1
1State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Abstract:
Ozonated secondary effluents (SEs) from municipal wastewater treatment plants (MWTPs) have been found to cause developmental retardation of fish embryos. This study explored the potential cause of the embryo toxicity formed in ozonated SEs by exposing Japanese medaka (Oryzias latipes) (d-rR) embryos to ozonated SE from a MWTP in Tianjin, China. The increase of ozone dose from 0.26 to 0.96 mg O3/mg DOC0 (consumed ozone per initial DOC), which produced total aldehyde (mixture of formaldehyde, acetaldehyde, propionaldehyde, and glyoxal) from 41.5 to 114.7 μg/L, resulted in an increase in the percentage of deformed larvae from 2.2% to 24.1%. Increases in larval deformity and embryo mortality were also observed in ozonated SEs from other MWTPs. The exposure experiment using the mixture aldehyde solution showed that the production of aldehydes could explain approximately 13.6% of larval deformity caused by ozonation of SEs. Pilot experimental results in Tianjin and Beijing, China showed that biofiltration as a post-treatment technology was effective in removing the aldehydes as well as reducing embryo toxicity caused by ozonation.
