Mark J. Benotti

Evaluation of a photocatalytic reactor membrane pilot system for the removal of pharmaceuticals and endocrine disrupting compounds from water

A photocatalytic reactor membrane pilot system, employing UV/TiO(2) photocatalysis, was evaluated for its ability to remove thirty-two pharmaceuticals, endocrine disrupting compounds, and estrogenic activity from water. Concentrations of all compounds decreased following treatment, and removal followed pseudo-first-order kinetics as a function of the amount of treatment. Twenty-nine of the targeted compounds in addition to total estrogenic activity were greater than 70% removed while only three compounds were less than 50% removed following the highest level of treatment (4.24 kW h/m(3)). No estrogenically active transformation products were formed during treatment. Additionally, the unit was operated in photolytic mode (UV only) and photolytic plus H(2)O(2) mode (UV/H(2)O(2)) to determine the relative amount of energy required. Based on the electrical energy per order (EEO), the unit achieved the greatest efficiency when operated in photolytic plus H(2)O(2) mode for the conditions tested.

Endocrine disruptors and pharmaceuticals: implications for water sustainability

The presence of pharmaceuticals and endocrine disrupting compounds (EDCs) in the environment raises many questions about risk to the environment and risk to human health. Researchers have attributed adverse ecological effect effects to the presence of these compounds, particularly EDCs, though there is no consensus on what risk, if any, these compounds pose to human health. The scientific community is in the process of developing a better understanding of the occurrence, fate, and transport of pharmaceuticals and EDCs in the environment, including a better characterization of human exposure via drinking water. This paper provides a brief review of pharmaceuticals and EDCs in drinking water, as well as uses examples from Lake Mead, Nevada, USA, to highlight the issues associated with their fate and transport. Lastly, the effects of natural or anthropogenically driven processes, like natural seasonal flow or climate-change/prolonged drought are discussed as they are factors which can drastically alter environmental concentrations of these compounds. Without question, the propensity for the contamination of fresh water will rise as (1) human population continues to grow or (2) patterns of natural surface water slow and wastewater becomes a larger fraction of flow further highlighting the need for a more comprehensive understanding of their environmental behavior.

Reversible Reduction of Estrone to 17β-Estradiol by , , and Isolates from the Las Vegas Wash

Environmental endocrine-disrupting compounds (EDCs) are a growing concern as studies reveal their persistence and detrimental effects on wildlife. Microorganisms are known to affect the transformation of steroid EDCs; however, the diversity of estrogen-degrading microorganisms and the range of transformations they mediate remain relatively little studied. In mesocosms, low concentrations of added estrone (E1) and 17β-estradiol (E2) were removed by indigenous microorganisms from Las Vegas Wash water within 2 wk. Three bacterial isolates, sp. strain LVW-9, sp. strain LVW-12, and sp. strain LVW-PC, were enriched from Las Vegas Wash water on E1 and E2 and used for EDC transformation studies. In the presence of alternative carbon sources, LVW-9 and LVW-12 catalyzed near-stoichiometric reduction of E1 to E2 but subsequently reoxidized E2 back to E1; whereas LVW-PC minimally reduced E1 to E2 but effectively oxidized E2 to E1 after a 20-d lag. In the absence of alternative carbon sources, LVW-12 and LVW-PC oxidized E2 to E1. This report documents the rapid and sometimes reversible microbial transformation of E1 and E2 and the slow degradation of 17α-ethinylestradiol in urban stream water and extends the list of known estrogen-transforming bacteria to the genera and . These results suggest that discharge of steroid estrogens via wastewater could be reduced through tighter control of redox conditions and may assist in future risk assessments detailing the environmental fate of estrogens through evidence that microbial estrogen transformations may be affected by environmental conditions or growth status.

Association between degradation of pharmaceuticals and endocrine-disrupting compounds and microbial communities along a treated wastewater effluent gradient in Lake Mead

The role of microbial communities in the degradation of trace organic contaminants in the environment is little understood. In this study, the biotransformation potential of 27 pharmaceuticals and endocrine-disrupting compounds was examined in parallel with a characterization of the native microbial community in water samples from four sites variously impacted by urban run-off and wastewater discharge in Lake Mead, Nevada and Arizona, USA. Samples included relatively pristine Colorado River water at the upper end of the lake, nearly pure tertiary-treated municipal wastewater entering via the Las Vegas Wash, and waters of mixed influence (Las Vegas Bay and Boulder Basin), which represented a gradient of treated wastewater effluent impact. Microbial diversity analysis based on 16S rRNA gene censuses revealed the community at this site to be distinct from the less urban-impacted locations, although all sites were similar in overall diversity and richness. Similarly, Biolog EcoPlate assays demonstrated that the microbial community at Las Vegas Wash was the most metabolically versatile and active. Organic contaminants added as a mixture to laboratory microcosms were more rapidly and completely degraded in the most wastewater-impacted sites (Las Vegas Wash and Las Vegas Bay), with the majority exhibiting shorter half-lives than at the other sites or in a bacteriostatic control. Although the reasons for enhanced degradation capacity in the wastewater-impacted sites remain to be established, these data are consistent with the acclimatization of native microorganisms (either through changes in community structure or metabolic regulation) to effluent-derived trace contaminants. This study suggests that in urban, wastewater-impacted watersheds, prior exposure to organic contaminants fundamentally alters the structure and function of microbial communities, which in turn translates into greater potential for the natural attenuation of these compounds compared to more pristine sites.