Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41-100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors measured by the oxidation assay accounted for an average of 23% and 28% of total PFASs (i.e., precursors and perfluorinated carboxylates and sulfonates) in groundwater and solids samples, respectively. One precursor in AFFF, perfluorohexane sulfonamide amine, was observed on several highly contaminated soil and aquifer solids samples, but no other precursors present in AFFF formulations were detected in any samples at this field site. Suspected intermediate transformation products of precursors in AFFF that were directly measured accounted for approximately half of the total precursor concentration in samples from the training site. The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluorinated carboxylates and sulfonates. The precursors that have persisted at this site may generate significant amounts of additional perfluorinated carboxylates and sulfonates upon remediation of contaminated groundwater or aquifer solids.

A new method was developed to quantify concentrations of difficult-to-measure and unidentified precursors of perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acids in urban runoff. Samples were exposed to hydroxyl radicals generated by thermolysis of persulfate under basic pH conditions and perfluoroalkyl acid (PFAA) precursors were transformed to PFCAs of related perfluorinated chain length. By comparing PFCA concentrations before and after oxidation, the concentrations of total PFAA precursors were inferred. Analysis of 33 urban runoff samples collected from locations around the San Francisco Bay, CA indicated that PFOS (2.6-26 ng/L), PFOA (2.1-16 ng/L), and PFHxA (0.9-9.7 ng/L) were the predominant perfluorinated compounds detected prior to sample treatment. Following oxidative treatment, the total concentrations of PFCAs with 5-12 membered perfluoroalkyl chains increased by a median of 69%, or between 2.8 and 56 ng/L. Precursors that produced PFHxA and PFPeA upon oxidation were more prevalent in runoff samples than those that produced PFOA, despite lower concentrations of their corresponding perfluorinated acids prior to oxidation. Direct measurements of several common precursors to PFOS and PFOA (e.g., perfluorooctanesulfonamide and 8:2 fluorotelomer sulfonate) accounted for less than 25% of the observed increase in PFOA, which increased by a median value of 37%. Exposure of urban runoff to sunlight, advanced oxidation processes, or microbes could result in modest, but measurable, increases in concentrations of PFCAs and PFSAs.

The corrosion of zero-valent iron (Fe0(s)) by oxygen (O2) can lead to the oxidation of organic compounds. To gain insight into the reaction mechanism and to assess the nature of the oxidant, the oxidation of methanol, ethanol, 2-propanol, and benzoic acid by the reaction of nanoparticulate zero-valent iron (nZVI) or ferrous iron (Fe[II]) with O2 in the absence of ligands was studied. At pH values below 5, Fe0(s) nanoparticles were oxidized by O2 within 30 min with a stoichiometry of approximately two Fe0(s) oxidized per O2 consumed. The yield of methanol and ethanol oxidation products increased from 1% at acidic pH to 6% at pH 7, relative to nZVI added. Product yields from 2-propanol and benzoic acid were highest under acidic conditions, with little oxidation observed at neutral pH. At pH values below 5, product formation was attributable to hydroxyl radical (OH.) production through the Fenton reaction, involving hydrogen peroxide and Fe(II) produced during nZVI oxidation. At higher pH values, the oxidation of Fe(II), the initial product of nZVI oxidation, by oxygen is responsible for most of the oxidant production. Product yields at circumneutral pH values were consistent with a different oxidant, such as the ferryl ion (Fe[IV]).

N-Nitrosodimethylamine (NDMA) is a member of a family of extremely potent carcinogens, the N-nitrosamines. Until recently, concerns about NDMA mainly focused on the presence of NDMA in food, consumer products, and polluted air. However, current concern focuses on NDMA as a drinking water contaminant resulting from reactions occurring during chlorination or via direct industrial contamination. Because of the relatively high concentrations of NDMA formed during wastewater chlorination, the intentional and unintentional reuse of municipal wastewater is a particularly important area of concern. Although ultraviolet (UV) treatment can effectively remove NDMA, there is considerable interest in the development of less expensive alternative treatment technologies. These alternative technologies include approaches for removing organic nitrogen-containing NDMA precursors prior to chlorination and the use of sunlight photolysis, and in situ bioremediation to remove NDMA and its precursors.

Electrochemical processes have been extensively investigated for the removal of a range of organic and inorganic contaminants. The great majority of these studies were conducted using nitrate-, perchlorate-, sulfate-, and chloride-based electrolyte solutions. In actual treatment applications, organic and inorganic constituents may have substantial effects on the performance of electrochemical treatment. In particular, the outcome of electrochemical oxidation will depend on the concentration of chloride and bromide. Formation of chlorate, perchlorate, chlorinated, and brominated organics may compromise the quality of the treated effluent. A critical review of recent research identifies future opportunities and research needed to overcome major challenges that currently limit the application of electrochemical water treatment systems for industrial and municipal water and wastewater treatment. Given the increasing interest in decentralized wastewater treatment, applications of electrolytic systems for treatment of domestic wastewater, greywater, and source-separated urine are also included. To support future adoption of electrochemical treatment, new approaches are needed to minimize the formation of toxic byproducts and the loss of efficiency caused by mass transfer limitations and undesired side reactions. Prior to realizing these improvements, recognition of the situations where these limitations pose potential health risks is a necessary step in the design and operation of electrochemical treatment systems.

Zero-valent iron nanoparticles (nano-Fe0) in aqueous solution rapidly inactivated Escherichia coli (E. coli). A strong bactericidal effect of nano-Fe0 was found under deaerated conditions, with a linear correlation between log inactivation and nano-Fe0 dose (0.82 log inactivation / mg/L nano-Fe0 · hr). The inactivation of E. coli under air saturation required much higher nano-Fe0 doses due to the corrosion and surface oxidation of nano-Fe0 by dissolved oxygen. Significant physical disruption of the cell membranes was observed in E. coli exposed to nano-Fe0, which may have caused the inactivation, or enhanced the biocidal effects of dissolved iron. The reaction of Fe(II) with intracellular oxygen or hydrogen peroxide also may have induced oxidative stress by producing reactive oxygen species. The bactericidal effect of nano-Fe0 was a unique property of nano-Fe0, which was not observed in other types of iron-based compounds.

For over 70 years, scientists have reported that certain synthetic and natural compounds could mimic natural hormones in the endocrine systems of animals. These substances are now collectively known as endocrine-disrupting compounds (EDCs), and have been linked to a variety of adverse effects in both humans and wildlife. More recently, pharmaceuticals and personal care products (PPCPs) have been discovered in various surface and ground waters, some of which have been linked to ecological impacts at trace concentrations. The majority of EDCs and PPCPs are more polar than traditional contaminants and several have acidic or basic functional groups. These properties, coupled with occurrence at trace levels (i.e., ,1 mg/L), create unique challenges for both removal processes and analytical detection. Reports of EDCs and PPCPs in water have raised substantial concern among the public and regulatory agencies; however, very little is known about the fate of these compounds during drinking and wastewater treatment. Numerous studies have shown that conventional drinking and wastewater treatment plants can not completely remove many EDCs and PPCPs. Oxidation with chlorine and ozone can result in transformation of some compounds with reactive functional groups under the conditions employed in water and wastewater treatment plants. Advanced treatment technologies, such as activated carbon and reverse osmosis, appear viable for the removal of many trace contaminants including EDCs and PPCPs. Future research needs include more detailed fate and transport data, standardized analytical methodology, predictive models, removal kinetics, and determination of the toxicological relevance of trace levels of EDCs and PPCPs in water.Key words: endocrine disruptor; pharmaceutical; drinking water; wastewater; treatment; review 449 ENDOCRINE DISRUPTING COMPOUNDS P ERHAPS THE MOST DIFFICULT PART of understanding the subject of endocrine disruption involves a definition of the term. The Environmental Protection Agency (EPA) has defined environmental endocrine disrupting compounds (EDCs) as exogenous agents that interfere with the "synthesis, secretion, transport, binding, action, or elimi- nation of natural hormones in the body that are responsible for the maintenance of homeostasis, reproduction, development, and/or behavior" (EPA, 1997). However, definitions and opinions on what defines an EDC vary greatly. It is generally accepted that the three major classes of endocrine disruption endpoints are estrogenic (compounds that mimic or block natural estrogen), androgenic (compounds that mimic or block natural testosterone), and thyroidal (compounds with direct or indirect impacts to the thyroid). As we will illustrate, the majority of research thus far has focused only on estrogenic compounds; however, disruption of androgen and thyroid function may be of greater or equal importance biologically.Although the topic of endocrine disruption is considered an "emerging issue" in the water industry, scientists have known about the ability o...

Chlorine disinfection of secondary wastewater effluent and drinking water can result in the production of the potent carcinogen N-nitrosodimethylamine (NDMA) at concentrations of approximately 100 and 10 parts per trillion (ng/L), respectively. Laboratory experiments with potential NDMA precursors indicate that NDMA formation can form during the chlorination of dimethylamine and other secondary amines. The formation of NDMA during chlorination may involve the slow formation of 1,1-dimethylhydrazine by the reaction of monochloramine and dimethylamine followed by its rapid oxidation to NDMA and other products including dimethylcyanamide and dimethylformamide. Other pathways also lead to NDMA formation during chlorination such as the reaction of sodium hypochlorite with dimethylamine. However, the rate of NDMA formation is approximately an order of magnitude slower than that observed when monochloramine reacts with dimethylamine. The reaction exhibits a strong pH dependence due to competing reactions. It may be possible to reduce NDMA formation during chlorination by removing ammonia prior to chlorination, by breakpoint chlorination, or by avoidance of the use of monochloramine for drinking water disinfection.