Assessing the sources, quantities, and trends on human waste contamination along protected south Florida ecosystem: A chemical tracer based study

The common occurrence of human derived contaminants like pharmaceuticals, steroids and hormones in surface waters has raised the awareness of the role played by the release of treated or untreated sewage in the water quality along sensitive coastal ecosystems. South Florida is home to many important protected environments ranging from wetlands to coral reefs which are in close proximity to large metropolitan cities. Since large portions of South Florida and most of the Florida Keys population are not served by modern sewage treatment plants and rely heavily on the use of inefficient septic systems; a comprehensive survey of selected human waste contamination markers is needed in these areas to assess water quality with respect to non-traditional micro-constituents. ^ This study reports the development and application of new sensitive and selective analytical methods for the fast screening of multiple wastewater tracers, classified as Emergent Pollutants of Concern (EPOC). Novel methods for the trace analysis of non-traditional markers of human-specific contamination such as aminopropanone were developed and used to assess the potential of non-traditional markers as wastewater tracers. ^ During our investigation, surface water samples collected from near shore environments along the South Florida were analyzed for fifteen hormones and steroids, and five commonly detected pharmaceuticals. The compounds most frequently detected were: coprostanol, cholesterol, estrone, β-estradiol, caffeine, triclosan and DEET. Concentrations of caffeine, bisphenol A and DEET were usually higher and more prevalent than the hormonal steroids. In general, it was found that common pharmaceuticals and steroids are widely present in major coastal environments in South Florida. It is also evident that aquatic bodies in heavily urbanized sectors such as the Miami River and Key Largo Harbor contain higher concentrations of several compounds while relatively open bay waters and agricultural areas show reduced chemical signatures. Concentrations of hormones in the Little Venice area of Marathon Key were above the Lowest Observable Effect Levels (LOELs) for several species, indicating that biological resources in this area are at risk. Water quality issues in some of these coastal water environments go beyond eutrophication, thus EPOC should be the target goal for future mitigation projects. ^

The nitrate to ammonia and ceramic (NAC) process for the denitration and immobilization of low-level radioactive liquid waste (LLW)

Hazardous radioactive liquid waste is the legacy of more than 50 years of plutonium production associated with the United States' nuclear weapons program. It is estimated that more than 245,000 tons of nitrate wastes are stored at facilities such as the single-shell tanks (SST) at the Hanford Site in the state of Washington, and the Melton Valley storage tanks at Oak Ridge National Laboratory (ORNL) in Tennessee. In order to develop an innovative, new technology for the destruction and immobilization of nitrate-based radioactive liquid waste, the United State Department of Energy (DOE) initiated the research project which resulted in the technology known as the Nitrate to Ammonia and Ceramic (NAC) process. However, inasmuch as the nitrate anion is highly mobile and difficult to immobilize, especially in relatively porous cement-based grout which has been used to date as a method for the immobilization of liquid waste, it presents a major obstacle to environmental clean-up initiatives. Thus, in an effort to contribute to the existing body of knowledge and enhance the efficacy of the NAC process, this research involved the experimental measurement of the rheological and heat transfer behaviors of the NAC product slurry and the determination of the optimal operating parameters for the continuous NAC chemical reaction process. Test results indicate that the NAC product slurry exhibits a typical non-Newtonian flow behavior. Correlation equations for the slurry's rheological properties and heat transfer rate in a pipe flow have been developed; these should prove valuable in the design of a full-scale NAC processing plant. The 20-percent slurry exhibited a typical dilatant (shear thickening) behavior and was in the turbulent flow regime due to its lower viscosity. The 40-percent slurry exhibited a typical pseudoplastic (shear thinning) behavior and remained in the laminar flow regime throughout its experimental range. The reactions were found to be more efficient in the lower temperature range investigated. With respect to leachability, the experimental final NAC ceramic waste form is comparable to the final product of vitrification, the technology chosen by DOE to treat these wastes. As the NAC process has the potential of reducing the volume of nitrate-based radioactive liquid waste by as much as 70 percent, it not only promises to enhance environmental remediation efforts but also effect substantial cost savings. ^

Determination of vertical and horizontal pathways of injected fresh wastewater into a deep saline aquifer (Florida, USA) using natural chemical tracers

Two deep-well injection sites in south Florida, USA, inject an average of 430 million liters per day (MLD) of treated domestic fresh wastewater into a deep saline aquifer 900 m below land surface. Elevated levels of NH3 (highest concentration 939 µmol) in the overlying aquifer above ambient concentrations (concentration less than 30 µmol) were evidence of the upward migration of injected fluids. Three pathways were distinguished based on ammonium, chloride and bromide ratios, and temperature. At the South District Wastewater Treatment Plant, the tracer ratios showed that the injectate remained chemically distinct as it migrated upwards through rapid vertical pathways via density-driven buoyancy. The warmer injectate (mean 28°C) retained the temperature signal as it vertically migrated upwards; however, the temperature signal did not persist as the injectate moved horizontally into the overlying aquifers. Once introduced, the injectate moved slowly horizontally through the aquifer and mixed with ambient water. At the North District Wastewater Treatment Plant, data provide strong evidence of a one-time pulse of injectate into the overlying aquifers due to improper well construction. No evidence of rapid vertical pathways was observed at the North District Wastewater Treatment Plant.