FATE OF ESTROGENS IN A NITRIFYING SEQUENCING BATCH REACTOR RECEIVING A HIGH ORGANIC STRENGTH, NITROGEN-RICH INDUSTRIAL WASTEWATER

The fate of six estrogenic compounds during aerobic biological treatment of a high strength industrial wastewater was examined in a bench-scale sequencing batch reactor. Both free and conjugated forms of the estrogens were analyzed. Custom GC/MS analytical methods were developed by others and used during this study to measure both soluble and solids-associated estrogens. A complete mass balance was developed around the reactor for each individual estrogen compound by accounting for influent mass loading, effluent decant mass loading (liquid and solids-associated), mass loading in the biomass waste stream (liquid and solids-associated), and volatilization of the estrogens in the off-gas. The discrepancy between the influent and other mass loadings was attributed to biodegradation and/or biotransformation. Biodegradation/biotransformation levels of 77.3–99.9% were realized for individual compounds. Overall biodegradation/biotransformation levels of 99% were realized for the aggregate of estrogens tested. These removal percentages were realized for estrogens that were present individually at concentrations from 3.3 to 550 μg/L in the influent. This study corroborates successful removal of individual estrogens during operation of a pilot-scale membrane bioreactor (MBR) from a pharmaceutical manufacturing wastewater (Helmig et al., 2005), thereby further demonstrating the promising application of standard aerobic biological treatment methods to meet increasingly stringent discharge limits of estrogens from industrial operations.