Screening of human antibiotic substances and determination of weekly mass flows in five sewage treatment plants in Sweden

Twelve antibiotic substances for human use, including trimethoprim and representatives of the fluoroquinolone (FQ), sulfonamide (SA), penicillin (PE), cephalosporin (CE), nitroimidazole (NI), tetracycline (TC), and macrolide (MA) groups, were subjected to a screening study at five Swedish sewage treatment plants (STPs) during one week in 2002 and one week in 2003. The analytes were extracted from raw sewage water, final effluent, and sludge by solid-phase extraction (SPE) or liquid-solid extraction (as appropriate) and then identified and quantified by liquid chromatography/tandem mass spectrometry. The mostfrequently detected antibiotics in the matrices considered in this study were norfloxacin, ofloxacin, ciprofloxacin, trimethoprim, sulfamethoxazole, and doxycycline. The other analytes were only detected in a few samples. Analysis of the weekly mass flows through each STP showed that FQs were partly eliminated from the water during sewage water treatment and the highest amounts of these substances were found in sludge. Sulfamethoxazole and trimethoprim were mainly found in raw sewage water and final effluent, but these substances had balancing mass flows, indicating that they too can withstand sewage water treatment. The mass flow patterns for doxycycline were more complex, with high amounts occurring in sludge in some cases, suggesting thatthe behavior of this analyte may be more strongly influenced by the treatment process and other variables at individual STPs. The environmental load (the sum of the amounts in the final effluent and sludge) normalized to the number of inhabitants in the catchment area of each investigated STP compared with theoretical predictions based on consumption data (in parentheses) showed good correlations: norfloxacin, 0.8 (0.9); ofloxacin, 0.3 (0.2); ciprofloxacin, 1.3 (3.5); sulfamethoxazole, 0.2 (0.4); trimethoprim, 1.1 (1.0); and doxycycline, 0.7 (0.4) mg per person per week. The results show that reasonably accurate predictions of environmental load of these antibiotics can be time-effectively derived from consumption data without additional measurements.     

Environmental exposure and risk assessment of fluoroquinolone antibacterial agents in wastewater and river water of the Glatt Valley Watershed,Switzerland

The mass flows of fluoroquinolone antibacterial agents (FQs) were investigated in the aqueous compartments of the Glatt Valley Watershed, a densely populated region in Switzerland. The major human-use FQs consumed in Switzerland, ciprofloxacin (CIP) and norfloxacin (NOR), were determined in municipal wastewater effluents and in the receiving surface water, the Glatt River. Individual concentrations in raw sewage and in final wastewater effluents ranged from 255 to 568 ng/L and from 36 to 106 ng/L, respectively. In the Glatt River, the FQs were present at concentrations below 19 ng/L. The removal of FQs from the water stream during wastewater treatment was between 79 and 87%. During the studied summer period, FQs in the dissolved fraction were significantly reduced downstream in the Glatt River (15-20 h residence time) (66% for CIP and 48% for NOR). Thus, after wastewater treatment, transport in rivers causes an additional decrease of residual levels of FQs in the aquatic environment. Refined predicted environmental concentrations for the study area compare favorably with the measured environmental concentrations (MEC) obtained in the monitoring study. Total measured FQ concentrations occurring in the examined aquatic compartments of the Glatt Valley Watershed were related to acute ecotoxicity data from the literature. The risk quotients obtained (MEC/PNEC < 1) following the recommendations of the European guidelines or draft documents suggest a low probability for adverse effects of the occurring FQs, either on microbial activity in WWTPs or on algae, daphnia, and fish in surface waters.     

Fluorochemical mass flows in a municipal wastewater treatment facility

Fluorochemicals have widespread applications and are released into municipal wastewater treatment plants via domestic wastewater. A field study was conducted at a full-scale municipal wastewater treatment plant to determine the mass flows of selected fluorochemicals. Flow-proportional, 24 h samples of raw influent, primary effluent, trickling filter effluent, secondary effluent, and final effluent and grab samples of primary, thickened, activated, and anaerobically digested sludge were collected over 10 days and analyzed by liquid chromatography electrospray-ionization tandem mass spectrometry. Significant decreases in the mass flows of perfluorohexane sulfonate and perfluorodecanoate occurred during trickling filtration and primary clarification, while activated sludge treatment decreased the mass flow of perfluorohexanoate. Mass flows of the 6:2 fluorotelomer sulfonate and perfluorooctanoate were unchanged as a result of wastewater treatment, which indicates that conventional wastewater treatment is not effective for removal of these compounds. A net increase in the mass flows for perfluorooctane and perfluorodecane sulfonates occurred from trickling filtration and activated sludge treatment. Mass flows for perfluoroalkylsulfonamides and perfluorononanoate also increased during activated sludge treatment and are attributed to degradation of precursor molecules.     

Stimulation of anaerobic digestion of thickened sewage sludge by iron-rich sludge produced by the fenton method

In batch mesophilic anaerobic digestion of a mixture of iron-rich sludge collected from Fenton treatment of molasses wastewater (MWW) and thickened sewage sludge from a municipal wastewater treatment plant, the methane content in the gas from the mixture was significantly higher than that from thickened sewage sludge only. When minerals in iron-rich sludge obtained by incineration were fed to thickened sewage sludge in semi-continuous experiments, the methane content obtained by digestion of thickened sewage sludge only increased approximately from 53% to 64%. These results suggest that iron-rich sludge can enhance methane production for thickened sewage sludge.     

Oxidative transformation of fluoroquinolone antibacterial agents and structurally related amines by manganese oxide

Various members of the popular fluoroquinolone antibacterial agents (FQs) have been frequently detected in municipal wastewater and surface water bodies in recent years. This study was conducted to gain a better understanding of the fate of FQs in the sediment-water environment. Seven FQs were examined for adsorptive and oxidative interactions with delta-MnO2 under environmental conditions and exhibited reactivity in the order of ciprofloxacin approximately enrofloxacin approximately norfloxacin approximately ofloxacin > lomefloxacin > pipemidic acid > flumequine. Four amines that are structurally related to the aniline and piperazine functional groups of FQs showed reactivity to oxidation by delta-MnO2 in the order of 1-phenylpiperazine > aniline > N-phenylmorpholine > 4-phenylpiperidine. Comparison among the above compounds clearly indicates thatthe piperazine moiety of FQs is the predominant adsorptive and oxidative site to MnO2. Product analyses showed that oxidation by MnO2 results in dealkylation and hydroxylation at the piperazine moiety of FQs, with the quinolone ring essentially intact. The reaction kinetics, reactivity comparison, and product characterization point to a surface reaction mechanism that likely begins with formation of a surface complex between FQ and the surface-bound MnIV, followed by oxidation at the aromatic N1 atom of FQ's piperazine moietyto generate an anilinyl radical intermediate. The radical intermediates subsequently undergo N-dealkylation, C-hydroxylation, and possibly coupling to yield a range of products. Even though the quinolone ring appears to be stable with respect to MnO2, it affects the overall reactivity and potentially product distribution of FQs via substituent effects. Results of this study strongly suggest that manganese oxides commonly present in soils will likely play an important role in the abiotic degradation of fluoroquinolone antibacterial agents in the environment.     

Hybrid life-cycle environmental and cost inventory of sewage sludge treatment and end-use scenarios: a case study from China

Sewage sludge management poses environmental, economic, and political challenges for wastewater treatment plants and municipalities around the globe. To facilitate more informed and sustainable decision making, this study used life-cycle inventory (LCI) to expand upon previous process-based LCIs of sewage sludge treatmenttechnologies. Additionally, the study evaluated an array of productive end-use options for treated sewage sludge, such as fertilizer and as an input into construction materials, to determine how the sustainability of traditional manufacturing processes changes with sludge as a replacement for other raw inputs. The inclusion of the life-cycle of necessary inputs (such as lime) used in sludge treatment significantly impacts the sustainability profiles of different treatment and end-use schemes. Overall, anaerobic digestion is generally the optimal treatment technology whereas incineration, particularly if coal-fired, is the most environmentally and economically costly. With respect to sludge end use, offsets are greatest for the use of sludge as fertilizer, but all of the productive uses of sludge can improve the sustainability of conventional manufacturing practices. The results are intended to help inform and guide decisions about sludge handling for existing wastewater treatment plants and those that are still in the planning phase in cities around the world. Although additional factors must be considered when selecting a sludge treatment and end-use scheme, this study highlights how a systems approach to planning can contribute significantly to improving overall environmental sustainability.     

Use of the chiral pharmaceutical propranolol to identify sewage discharges into surface waters

The discharge of relatively small volumes of untreated sewage is a source of wastewater-derived contaminants in surface waters that is often ignored because it is difficult to discriminate from wastewater effluent. To identify raw sewage discharges, we analyzed the two enantiomers of the popular chiral pharmaceutical, propranolol, after derivitization to convert the enantiomers to diastereomers. The enantiomeric fraction (the ratio of the concentration of one of its isomers to the total concentration) of propranolol in the influent of five wastewater treatment plants was 0.50 +/- 0.02, while after secondary treatment it was 0.42 or less. In a laboratory study designed to simulate an activated sludge municipal wastewater treatment system, the enantiomeric fraction of propranolol decreased from 0.5 to 0.43 as the compound underwent biotransformation. In a similar system designed to simulate an effluent-dominanted surface water, the enantiomeric fraction of propranolol remained constant as it underwent biotransformation. Analysis of samples from surface waters with known or suspected discharges of untreated sewage contained propranolol with an enantiomeric fraction of approximately 0.50 whereas surface waters with large discharges of wastewater effluent contained propranolol with enantiomeric fractions similar to those observed in wastewater effluent. Measurement of enantiomers of propranolol may be useful in detecting and documenting contaminants related to leaking sewers and combined sewer overflows.     

Nitrate content of lettuce (Lactuca sativa L.) after fertilization with sewage sludge and irrigation with treated wastewater

A romaine-type lettuce (Lactuca sativa L.) was cultivated over three crop seasons (spring 2005, spring 2006 and autumn–winter 2006) in six 36 m² plots in Alcázar de San Juan, Spain. A drip irrigation system was used to water all plots: five plots with drinking water and one plot with wastewater from the activated sludge system of a wastewater treatment plant (WWTP). One drinking water-irrigated plot was not fertilized (control). Five different treatments were applied to the soil: three organic mixtures (sewage sludge, sewage sludge mixed with pine bark and municipal solid waste with composted sludge) and a conventional fertilizer were applied to the four plots irrigated with drinking water. The last plot was irrigated with treated wastewater. The treatments were tested for their effect on plant growth and nitrate concentration in vegetable tissue. An increase in fresh weight in the lettuce was linked to the dosage of sewage sludge. The highest nitrate level was observed in the sewage sludge treatment in all crops and seasons, although, in general, all values were below the maximum limits established by the European Commission for nitrate content in fresh romaine lettuce. In the third crop season, a significant increase in nitrate content was observed in lettuce from organic treatments. Nitrate concentration in lettuce from irrigated treated wastewater was higher than control, although significant differences were not found.     

Dissipation of fragrance materials in sludge-amended soils

A possible removal mechanism for fragrance materials (FMs) in wastewater is adsorption to sludge, and sludge application to land may be a route through which FMs are released to the soil environment. However, little is known about the concentrations and fate of FMs in soil receiving sludge application. This study was conducted to better understand the dissipation of FMs in sludge-amended soils. We first determined the spiking and extraction efficiencies for 22 FMs in soil and leachate samples. Nine FMs were detected in digested sludges from two wastewater treatment plants in Delaware using these methods. We conducted a 1-year die-away experiment which involved four different soils amended with sludge, with and without spiking of the 22 FMs. The initial dissipation of FMs in all spiked trays was rapid, and only seven FMs remained at concentrations above the quantification limits after 3 months: AHTN, HHCB, musk ketone, musk xylene, acetyl cedrene, OTNE, and DPMI. After 1 year, the only FMs remaining in all spiked trays were musk ketone and AHTN. DPMI was the only FM that leached significantly from the spiked trays, and no FMs were detected in leachate from any unspiked tray. While soil organic matter content affected the dissipation rate in general, different mechanisms (volatilization, transformation, leaching) appeared to be important for different FMs.     

Behavior of fluoroquinolones and trimethoprim during mechanical, chemical, and active sludge treatment of sewage water and digestion of sludge

The behavior and fate of three fluoroquinolones (norfloxacin, ofloxacin, and ciprofloxacin), one sulfonamide (sulfamethoxazole), and trimethoprim were investigated at a sewage treatment plant in Ume?, Sweden, in 2004. This plant uses conventional mechanical, chemical, and activated sludge methods to treat the sewage water and digest the sludge; the dewatered digested sludge is pelleted (dry weight > 90% of total weight). Raw sewage water and particles as well as effluents and sludge from specific treatment areas within the plant were sampled. In addition to quantifying the antibiotics within the plant, we characterized the sample matrixes to facilitate evaluation of the results. Of the five substances examined, only norfloxacin, ciprofloxacin, and trimethoprim were present in concentrations higher than their limits of quantification. Norfloxacin and ciprofloxacin sorbed to sludge in a manner that was independent of changes in pH during sewage treatment, and more than 70% of the total amount of these compounds passing through the plant was ultimately found in the digested sludge. The results suggest that fluoroquinolones undergo thermal degradation during pelleting, but more studies are needed to confirm this. Trimethoprim was found in the final effluent at approximately the same concentration and mass flow as in the raw sewage, and could not be quantified in any solid sample. Predicted environmental concentrations, based on consumption data for Ume? municipality, correlated well with the results obtained, especially when the predicted concentrations were corrected to account for the amount of each active substance excreted in urine. The results obtained were compared to those of previous studies of these three substances' behavior and fate and were found to be similar, although some of the other plants studied employed the various treatment steps in different orders.     

A simple method for the determination of fluoroquinolone residues in tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus) employing LC-MS/MS QToF

The use of antimicrobials in livestock production is a powerful resource applied throughout the world to guarantee high yield and control bacterial diseases in aquaculture. However, residues of these substances in animal products represent a potential risk to consumer health when residue levels are above the established maximum residue limits (MRLs). Fluoroquinolones (FQs) are antimicrobials commonly used worldwide in aquaculture. The aim of this work was to develop and validate a simple analytical method for the simultaneous determination of norfloxacin, danofloxacin, enrofloxacin and ciprofloxacin levels in tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus) fillets using liquid chromatography–tandem mass spectrometry (LC-MS/MS) quadrupole time of flight (QToF). The FQs were extracted from the fillets with 1% acetic acid–methanol and 1% acetic acid–acetonitrile solutions using ultrasonic assistance. The clean-up was performed with hexane. Chromatographic separation was conducted in an XTerra RP18 column (2.1 × 150 mm, 5 µm) at 25 °C with a flow of 0.2 mL min^?1. The mobile phase consisted of 0.1% aqueous formic acid and acetonitrile, with gradient elution. The validation parameters for all FQs were linearity (>0.99), intra-day precision (CV of 1%–9%), inter-day precision (CV of 3%–17%), decision limit (63–126 ng g^?1), detection capability (76 –152 ng g^?1) and accuracy (90%–111%). The limit of quantification was lower than the MRL for each FQ, indicating that the method is suitable for the determination of the FQ levels in the fish fillets. The mass analyser of the QToF type was able to confirm the identities of the FQs with an error of the accuracy of the mass (reasons m/z) of less than 10 ppm.     

Occurrence and solid-liquid partition of sulfonated naphthalene-formaldehyde condensates in the aquatic environment

Sulfonated naphthalene-formaldehyde condensates (SNFC) are high production volume chemicals used in a variety of applications, for example, as concrete plasticizers, tanning agents, or dye dispersants. They enter the aquatic environment primarily by the wastewater path. The occurrence and fate of the monomers, which are different isomers of mono- and disulfonated naphthalene, was intensively investigated in previous studies. However, the environmental fate of the persistent higher molecular SNFC is so far widely unknown. This paper describes an ultrasonic extraction under alkaline conditions, followed by ion-pair HPLC with fluorescence detection for the analysis of SNFC oligomers from solid environmental matrixes such as sewage sludge, suspended solids, and river sediments. Limits of quantification of about 0.1 mg kg-1 d.m. were well below the measured concentrations in environmental samples. SNFC were adsorbed to suspended solids and river sediments in three major German rivers (Rhine, Neckar, and Danube) in concentrations typically up to several mg kg(-1) d.m. A total content of about 4 g kg(-1) d.m. was measured in a sewage sludge of a municipal wastewater treatment plant, which receives wastewater from a textile dyeing plant. Furthermore, the first quantitative field data on the partition of SNFC and their monomers between the aqueous phase and solid environmental compartments are presented. Solid-liquid partition coefficients (Kd) of oligomers with a chain-length ranging from three to six naphthalenesulfonate units were derived from the analysis of corresponding wastewater and sewage sludge samples and from suspended solids and river water samples, respectively. Determined Kd values were in the range from 10(2) to 10(4) L kg(-1).     

Dried sludges and sludge-based chars for H2S removal at low temperature: influence of sewage sludge characteristics

The use of sewage sludge as a precursor of adsorbent/ catalyst materials for environmental applications has been encouraged during the past few years. Due to the heterogeneous nature of sludges, there exists a lack of information regarding the characteristics of these low-cost precursors and how their physicochemical properties affect the final performance of materials prepared from them. In this work, three sewage-sludges collected at WWTPs with assorted sludge/wastewater treatment schemes were used as precursors of adsorbents/catalysts for H2S removal at room temperature. All the solidswere characterized to establish their textural properties and chemical composition, including the speciation of the adsorbents/ catalysts inorganic fraction. Thermal treatment (gasification) of the raw (dried) sludges increased the H2S removal ability in all cases. For these thermally treated materials, catalytic conversion to elemental sulfur and sulfate moieties was found to be the main route of H2S removal. Results indicate that adsorbents based on an iron/calcium-containing sludge were the most reactive and exhibited the highest capacities for H2S retention. Forthis particulartype of sludge, a reasonably good performance was observed even when the dried (raw) sludge was used as adsorbent/ catalyst. Alternatively, the oxidation of H2S by chars obtained from the other two sludges under study was related to their textural properties.     

Carbamazepine and its metabolites in wastewater and in biosolids in a municipal wastewater treatment plant

Pharmaceutically active compounds (PhACs) are discharged into the environment from domestic wastewater treatment plants (WWTPs). In this study, we determined the distribution of the anti-epileptic drug, carbamazepine (CBZ), and its major metabolites and caffeine in both aqueous and solid phases through different treatment processes of a WWTP. A method was developed to extract samples of biosolids using pressurized liquid extraction (PLE), coupled with cleanup of extracts using solid-phase extraction. Samples of biosolids and wastewater were analyzed for caffeine and CBZ and five of its metabolites, 10,11-dihydro-10,11-epoxycarbamazepine (CBZ-EP), 11-dihydro-10,11-epoxycarbamazepine (CBZ-DiOH), 2-hydroxycarbamazepine (CBZ-20H), 3-hydroxycarbamazepine (CBZ-30H), and 10,11-dihydro-10-hydroxycarbamazepine (CBZ-100H). The analytes were quantified using liquid chromatography-electrospray ionization tandem mass spectrometry. The recoveries of the analytes were 82.1-91.3% from raw biosolids and 80.1-92.4% from treated biosolids, and the limits of detection were 0.06-0.50 and 0.06-0.40 microg/kg on a wet weight basis for raw and treated biosolids, respectively. The behavior of carbamazepine and its metabolites, together with caffeine as a marker of domestic inputs, was investigated in the WWTP for the City of Peterborough, ON, Canada, which utilizes secondary sewage treatment technologies. CBZ, CBZ-2OH, CBZ-30H, and CBZ-DiOH were detected at concentrations of 69.6, 1.9, 1.6, and 7.5 microg/kg (dry weight), respectively, in untreated biosolids and at concentrations of 258.1, 3.4, 4.3, and 15.4 microg/kg (dry weight), respectively, in treated biosolids. However, CBZ-EP and CBZ-100H were not detected in any of the biosolid samples. CBZ and its five metabolites were detected in all wastewater samples collected from four different stages of treatment. The results showed that 29% of the carbamazepine was removed from the aqueous phase during treatment in the WWTP, while the metabolites were not effectively removed. Concentrations of caffeine were reduced by 99.9% in the aqueous phase, which appeared to be due primarily to degradation. Caffeine was also detected at concentrations of 165.8 and 7.6 microg/kg (dry weight) in raw and treated biosolids, respectively. Because of differences in hydrophobicity, CBZ is the primary analyte in biosolids, while CBZ-DiOH is the primary analyte in the aqueous phase of the wastewater. A mass balance calculation showed that the majority of CBZ and its metabolites exist in the aqueous phase (i.e., wastewater), ratherthan in the biosolids, 78 g of CBZ and its metabolites enters the Peterborough WWTP daily, and 91 g is discharged from the WWTP daily in the combined suspended solids and aqueous phases of the wastewater. The calculated daily inputs into the WWTP are somewhat less than the inputs of 192 g estimated from Canadian annual sales data for CBZ.     

Partitioning, persistence, and accumulation in digested sludge of the topical antiseptic triclocarban during wastewater treatment

The topical antiseptic agent triclocarban (TCC) is a common additive in many antimicrobial household consumables, including soaps and other personal care products. Long-term usage of the mass-produced compound and a lack of understanding of its fate during sewage treatment motivated the present mass balance analysis conducted at a typical U.S. activated sludge wastewater treatment plant featuring a design capacity of 680 million liters per day. Using automated samplers and grab sampling, the mass of TCC contained in influent, effluent, and digested sludge was monitored by isotope dilution liquid chromatography (tandem) mass spectrometry. The average mass of TCC (mean +/- standard deviation) entering and exiting the plant in influent (6.1 +/- 2.0 microg/L) and effluent (0.17 +/- 0.03 microg/ L) was 3737 +/- 694 and 127 +/- 6 g/d, respectively, indicating an aqueous-phase removal efficiency of 97 +/- 1%. Tertiary treatment by chlorination and sand filtration provided no detectable benefit to the overall removal. Due to strong sorption of TCC to wastewater particulate matter (78 +/- 11% sorbed), the majority of the TCC mass was sequestered into sludge in the primary and secondary clarifiers of the plant. Anaerobic digestion for 19 days did not promote TCC transformation, resulting in an accumulation of the antiseptic compound in dewatered, digested municipal sludge to levels of 51 +/- 15 mg/kg dry weight (2815 +/- 917 g/d). In addition to the biocide mass passing through the plant contained in the effluent (3 +/- 1%), 76 +/- 30% of the TCC input entering the plant underwent no net transformation and instead partitioned into and accumulated in municipal sludge. Based on the rate of beneficial reuse of sludge produced by this facility (95%), which exceeds the national average (63%), study results suggest that approximately three-quarters of the mass of TCC disposed of by consumers in the sewershed of the plant ultimately is released into the environment by application of municipal sludge (biosolids) on land used in part for agriculture.     

Rapid detection of Nocardia amarae in the activated sludge process using enzyme-linked immunosorbent assay (ELISA)

Nocardia amarae, a mycolic acid-containing bacterium, has often been reported to cause foaming of activated sludge in wastewater treatment plants. In this study, the number of N. amarae cells in the activated sludge process was estimated by enzyme-linked immunosorbent assay (ELISA) with anti-N. amarae polyclonal antibody. Use of the antibody enabled N. amarae to be detected at levels of 10(4) to 10(7) colony forming units. On the other hand, the antibody reacted with only a small portion of activated sludge, in which no N. amarae cells were detected by the plate count method. Competitive ELISA was employed to estimate the N. amarae cells in samples taken from a municipal wastewater treatment plant, including raw wastewater and activated sludge foam. The cell numbers estimated by competitive ELISA corresponded well with those obtained by plate counts. Hence, the antibody produced in this study was shown to be effective for the rapid monitoring of N. amarae in the activated sludge process.     

Dimethyl sulfoxide (DMSO) waste residues and municipal waste water odor by dimethyl sulfide (DMS): the north-east WPCP plant of Philadelphia

This study shows for the first time that overlooked mg/L concentrations of industrial dimethyl sulfoxide (DMSO) waste residues in sewage can cause "rotten cabbage" odor problems bydimethyl sulfide (DMS) in conventional municipal wastewater treatment. In laboratory studies, incubation of activated sludge with 1-10 mg/L DMSO in bottles produced dimethyl sulfide (DMS) at concentrations that exceeded the odor threshold by approximately 4 orders of magnitude in the headspace gas. Aeration at a rate of 6 m3 air/m3 sludge resulted in emission of the DMS into the exhaust air in a manner analogous to that of an activated sludge aeration tank. A field study atthe NEWPCP sewage treatment plant in Philadelphia found DMSO levels intermittently peaking as high as 2400 mg/L in sewage near an industrial discharger. After 3 h, the DMSO concentration in the influent to the aeration tank rose from a baseline level of less than 0.01 mg/L to a level of 5.6 mg/L and the DMS concentration in the mixed liquor rose from less than 0.01 to 0.2 mg/L. Finding this link between the intermittent occurrence of DMSO residues in influent of the treatment plant and the odorant DMS in the aeration tank was the keyto understanding and eliminating the intermittent "canned corn" or "rotten cabbage" odor emissions from the aeration tank that had randomly plagued this plant and its city neighborhood for two decades. Sewage authorities should consider having wastewater samples analyzed for DMSO and DMS to check for this possible odor problem and to determine whether DMSO emission thresholds should be established to limit odor generation at sewage treatment plants.     

Azole fungicides: occurrence and fate in wastewater and surface waters

The mode of action of azole compounds implies a potential to affect endocrine systems of different organisms and is reason for environmental concern. The occurrence and fate of nine agricultural azole fungicides, some of them also used as biocides, and four azole pharmaceuticals were studied in wastewater treatment plants (WWTPs) and lakes in Switzerland. Two pharmaceuticals (fluconazole, clotrimazole, 10-110 ng L(-1)) and two biocides (propiconazole, tebuconazole, 1-30 ng L(-1)) were consistently observed in WWTP influents. Loads determined in untreated and treated wastewater indicated thatfluconazole, propiconazole, and tebuconazole were largely unaffected by wastewater treatment, but clotrimazole was effectively eliminated (> 80%). Incubation studies with activated sludge showed no degradation for fluconazole and clotrimazole within 24 h, but strong sorption of clotrimazole to activated sludge. Slow degradation and some sorption were observed for tebuconazole and propiconazole (degradation half-lives, 2-3 d). In lakes, fluconazole, propiconazole, and tebuconazole were detected at low nanogram-per-liter levels. Concentrations of the pharmaceutical fluconazole correlated with the expected contamination by domestic wastewater, but not those of the biocides. Per capita loads of propiconazole and tebuconazole in lakes suggested additional inputs; for example, from agricultural use or urban runoff rainwater.     

Determination of surfactants and some of their metabolites in untreated and anaerobically digested sewage sludge by subcritical water extraction followed by liquid chromatography-mass spectrometry

Enormous amounts of sewage sludge are worldwide generated and released into the environment. Analysis of the most common and/or toxic chemicals in sludge should be mandatory before deciding its destination. Surfactants and some of their breakdown products are invariably the most common organic contaminants in domestic sewage sludge. For determining these compounds, we have developed a method based on extraction with subcritical water followed by liquid chromatography-mass spectrometry. On extracting surfactants and their metabolites from 50 mg of sludge, the efficiency of the water extraction device was evaluated in terms of pH of the extractant, temperature, and time of the static extraction. The best extraction conditions were obtained by using carbonate buffer (pH 9.4) at 200 degrees C as extractant, 10 min of static extraction at the pressure of 100 bar followed by 17 min of dynamic extraction. Analyte collection was performed by inserting a solid-phase extraction cartridge downstream the extraction cell. Compared to 16-h Soxhlet extraction with methanol, this procedure was remarkably more efficient in extracting anionic surfactants and acidic metabolites of nonylphenol ethoxylates (NPECs). A short survey was conducted to estimate concentration changes of target compounds after 14-d sludge anaerobic digestion. Results showed that 54-74% of both neutral and weakly acidic ethoxylate species were removed after residence of the sludge in the digester. On the contrary, little, if any, removal of anionic surfactants was observed after the digestion treatment. As expected, the level of nonylphenol increased under anaerobic conditions.