Investigating the Processes Governing Hormone and Nonionic Surfactant Removal and Transport in On-Site Wastewater Treatment and Reuse

Measurable levels of endocrine disrupting compounds (EDCs) and pharmaceutically active compounds have been detected in septic systems at concentrations well above those shown to cause sexual and developmental abnormalities in vertebrate and invertebrate aquatic species. Specifically, compounds such as steroid hormones and nonionic surfactant metabolites (nonylphenols) are of particular interest because of their widespread use, high level of potency at low concentrations, and ubiquity in wastewaters. Although a few studies indicate that some of these EDCs could be partially removed or transformed during sewage and septic treatment, many of these compounds are still being found in the environment and in drinking water supplies. The results of our research indicate that using combinations of aerobic and anaerobic sand filters or sub-surface flow wetlands in on-site wastewater treatment systems can improve the overall quality of the final effluent and drastically reduces the concentration of steroid estrogens, nonylphenols, and estrogenic activity. Furthermore, the results indicate that the quality of treated effluent impacts the rate of transport and biotransformation of the steroid estrogens through soils after discharge from the on-site wastewater treatment systems. Thus, traditional systems with only a main tank and/or pump tank discharge relatively poor quality water (e.g., high TOC, high ammonia) with high EDC concentrations and estrogenic activity and has the potential to facilitate transport of such compounds to the groundwater environment. This presentation will highlight the key points of our findings among five full scale on-site wastewater treatment and non-potable reuse systems plus the implications of a bench-scale soil transport study.