Evaluation of the fate of perfluoroalkyl compounds in wastewater treatment plants

Recent studies have shown that the wastewater treatment plant (WWTP) is a significant source of perfluoroalkyl compounds (PFCs) in natural water. In this study, 10 PFCs were analyzed in influent and effluent wastewater and sludge samples in 15 municipal, 4 livestock and 3 industrial WWTPs in Korea. The observed distribution pattern of PFCs differed between the wastewater and sludge samples. Perfluorooctane sulfonate (PFOS) was dominant in the sludge samples with a concentration ranging from 3.3 to 54.1 ng/g, whereas perfluorooctanoic acid (PFOA) was dominant in wastewater and ranged from 2.3 to 615 ng/L and 3.4 to 591 ng/L in influent and effluent wastewater, respectively. Principal component analysis (PCA) results provided an explanation for this variation in PFC distribution patterns in the aqueous and sludge samples. The fates of PFCs in the WWTPs were related with the functional groups. The PFOS concentrations tended to decrease after treatment in most WWTPs, whereas PFOA increased. The different fates of PFOA and PFOS in WWTPs were attributed to the higher organic carbon-normalized distribution coefficient of perfluoroalkylsulfonate (PFASs) than that of the carboxylate analog, indicating the preference of PFASs to partition to sludge. Although industrial WWTPs contained high concentration of PFCs, they are not the main source of PFCs in Korean water environment because of their small release amount. WWTPs located in big cities discharged more PFCs, suggesting household sewage is one of the significant sources of PFCs contamination in the environment.     

Occurrence and removal of pharmaceuticals in a municipal sewage treatment system in the south of Sweden

The occurrence and removal rate of seven pharmaceuticals (ibuprofen, naproxen, diclofenac, fluoxetine, ofloxacin, norfloxacin, ciprofloxacin), two metabolites (norfluoxetine, clofibric acid), one degradation product (4-isobutylacetophenone) and 3 estrogens (17α-ethinylestradiol, 17β-estradiol, estrone) were studied in the inlet and outlet of a tertiary sewage treatment plant (STP) in Sweden as well as between different treatment steps in the STP which includes a conventional activated sludge step. Pharmaceuticals in raw household and raw hospital sewage streams leading to the STP were as well investigated. Hydraulic retention times (HRT) of each treatment step was considered for sampling and for the calculation of the removal rates. These rates were above 90%, except for diclofenac, clofibric acid, estrone and ofloxacin. However, only diclofenac and naproxen showed significant effluent loads (> 145 mg/d/1000 inh). Diclofenac was not eliminated during the treatment and in fact even higher concentrations were found at the effluent than in the inlet of the STP. 17α-Ethinylestradiol was not detected in any of the samples. Results indicate that a STP such as the one in Kristianstad, Sweden, with a tertiary treatment is sufficient to remove significantly most of the investigated pharmaceuticals. The chemical treatment improved the removal of several pharmaceuticals especially the antibiotics, which showed step removal rates between 55 and 70%. The expected concentration levels of the pharmaceuticals in the surface water (dilution 1 to 10) close to the outlet of the STP are below the no-observed effect-concentration (NOEC). However, despite that this would imply no important effects in the aquatic environment one cannot rule out negative consequences nearby the STP because most of the NOEC values are derived from acute toxicity data. This may underestimate the real impact of pharmaceuticals in the aquatic ecosystem.     

Pharmaceutical and personal care products in tile drainage following land application of municipal biosolids

Land application of municipal biosolids (sewage) is a common farming practice in many parts of the world. There is potential for transport of pharmaceuticals and personal care products (PPCPs) from agricultural fields to adjacent surface waters via tile drainage systems. In this study, liquid municipal biosolids (LMB) (total solids=11,933 mg L(-1)), supplemented with selected PPCPs and the fluorescent dye tracer rhodamine WT (RWT), were applied to tile drained fields using two land application approaches. Objectives included evaluating the relative benefits of land application practices with respect to reducing PPCP loadings to tile drains, evaluating PPCP persistence in tile water, and determining whether rhodamine WT can be used to estimate PPCP mass loads in tile. The PPCPs examined included an antibacterial agent used in personal care products (triclosan), a metabolite of nicotine (cotinine), and a variety of drugs including two sulfonamide antimicrobials (sulfapyridine, sulfamethoxazole), a beta-blocker (atenolol), an anti-epileptic (carbamazepine), an antidepressant (fluoxetine), analgesic/anti-inflammatories (acetaminophen, naproxen, ibuprofen), and a lipid-regulator (gemfibrozil). Maximum observed PPCP concentrations in the spiked LMB were about 10(3) ng g(-1) dry weight. PPCPs were shown to move rapidly via soil macropores to tile drains within minutes of the land application. Maximum observed PPCP concentrations in tile effluent associated with the LMB application-induced tile flow event were approximately 10(1) to 10(3) ng L(-1). PPCP mass loads, for the application-induced tile-hydrograph event, were significantly (p<0.1) higher for surface spreading over non-tilled soil (incorporation tillage occurring 20 h post-application), relative to aerating soil immediately prior to surface spreading using an AerWay slurry deposition system. PPCP concentrations that were detected above the limit of quantitation (LOQ) in tile water during several precipitation-induced tile flow events that occurred post-application, included: triclosan (max. approximately 1.5 x 10(2) ng L(-1)), carbamazepine (max. approximately 7 x 10(1) ng L(-1)), atenolol (max approximately 4 x 10(1) ng L(-1)), and cotinine (max approximately 2 x 10(1) ng L(-1)). In spite of their presence in biosolids, the other PPCPs were not observed above LOQ concentrations during these events. PPCP concentrations were predicted from RWT concentrations over a 40 day study period. Tile mass loads as a percent of PPCP mass applied to soil ranged from 4.2%+/-SD of 9.2% to 7.1%+/-10.9% for the AerWay system and surface spreading plus incorporation treatments, respectively.     

Productivity of wastewater treatment plants in the Valencia Region of Spain

This study analyses the evolution of productivity over the 2008–2012 period for a homogenous set of 199 wastewater treatment plants that are located in the Valencia Region of Spain and utilize the same treatment technology, using the smoothed bootstrap Malmquist productivity index based on Data Envelopment Analysis (DEA). The results reveal a negative trend in productivity that is mainly the result of resource management rather than an inappropriate level of innovation or use of new technologies. In addition, the effect of exogenous factors on productivity is analysed using the Kruskal-Wallis (KW) test, finding that productivity levels were affected by the quality of the influent water and the size of the plants, but not by the other factors considered.     

Pharmaceutical chemicals and endocrine disrupters in municipal wastewater in Tokyo and their removal during activated sludge treatment

We measured six acidic analgesics or anti-inflammatories (aspirin, ibuprofen, naproxen, ketoprofen, fenoprofen, mefenamic acid), two phenolic antiseptics (thymol, triclosan), four amide pharmaceuticals (propyphenazone, crotamiton, carbamazepine, diethyltoluamide), three phenolic endocrine disrupting chemicals (nonylphenol, octylphenol, bisphenol A), and three natural estrogens (17beta-estradiol, estrone, estriol) in 24-h composite samples of influents and secondary effluents collected seasonally from five municipal sewage treatment plants in Tokyo. Aspirin was most abundant in the influent, with an average concentration of 7300 ng/L (n = 16), followed by crotamiton (921 ng/L), ibuprofen (669 ng/L), triclosan (511 ng/L), and diethyltoluamide (503 ng/L). These concentrations were 1 order of magnitude lower than those reported in the USA and Europe. This can be ascribed to lower consumption of the pharmaceuticals in Japan. Aspirin, ibuprofen, and thymol were removed efficiently during primary + secondary treatment (> 90% efficiency). On the other hand, amide-type pharmaceuticals, ketoprofen, and naproxen showed poor removal (< 50% efficiency), which is probably due to their lower hydrophobicity (logKow < 3). Because of the persistence of crotamiton during secondary treatment, crotamiton was most abundant among the target pharmaceuticals in the effluent. This is the first paper to report ubiquitous occurrence of crotamiton, a scabicide, in sewage. Because crotamiton is used worldwide and it is persistent during secondary treatment, it is a promising molecular marker of sewage and secondary effluent.     

Usage of fuzzy modeling for cultivation of forests irigated by wastewater treatment plants

Cultivation of forests and plant species by utilizing processed wastewater and sludge from the wastewater treatment plants is an effective method to reduce the release of harmful substances and provide favorable conditions for the development of agricultural sector under the shortage of water resources. For this purpose, the experiments have been carrying out to investigate the ability of species to absorb chemical elements under increased concentrations in wastewater, as well as other characteristics and features of species’ behavior in biological, chemical and physical aspects. The behavior is a result of complex cause‐effect dynamical interactions in ecological networks with unknown mathematical models of underlying functional relationships. There are two important features inherent in the investigation of cultivating species by processed wastewater: empirical modeling of species’ behavior and qualitative reasoning with imprecise information about this behavior.

Proceeding from analysis of chains of interactions viewed as functional mappings between factors and investigated objects, the paper proposes a solution to the development of fuzzy modeling tools to support the investigation process. The proposed architecture includes the following components: a model that describes an ecological network under investigation; artificial neural network modules that model complex direct cause‐effect interactions; a fuzzy inference system that provides the investigator with qualitative reasoning about these interactions within a framework of the model; and control system that, under the requests from the investigator, controls the operation of the above components.     

Occurrence of androgens and progestogens in wastewater treatment plants and receiving river waters: Comparison to estrogens

Research has shown that exposure to androgens and progestogens can cause undesirable biological responses in the environment. To date, however, no detailed or direct study of their presence in wastewater treatment plants has been conducted. In this study, nine androgens, nine progestogens, and five estrogens were analyzed in influent and final effluent wastewaters in seven wastewater treatment plants (WWTPs) of Beijing, China. Over a period of three weeks, the average total hormone concentrations in influent wastewaters were 3562 (Wujiacun WWTP)-5400 ng/L (Fangzhuang WWTP). Androgens contributed 96% of the total hormone concentrations in all WWTP influents, with natural androgen (androsterone: 2977 ± 739 ng/L; epiandrosterone: 640 ± 263 ng/L; and androstenedione: 270 ± 132 ng/L) being the predominant compounds. The concentrations of synthetic progestogens (megestrol acetate: 41 ± 25 ng/L; norethindrone: 6.5 ± 3.3 ng/L; and medroxyprogesterone acetate: 6.0 ± 3.2 ng/L) were comparable to natural ones (progesterone: 66 ± 36 ng/L; 17α,20β-dihydroxy-4-progegnen-3-one: 4.9 ± 1.2 ng/L; 21α-hydroxyprogesterone: 8.5 ± 3.0 ng/L; and 17α-hydroxyprogesterone: 1.5 ± 0.95 ng/L), probably due to the wide and relatively large usage of synthetic progestogens in medical therapy. In WWTP effluents, androgens were still the dominant class accounting for 60% of total hormone concentrations, followed by progestogens (24%), and estrogens (16%). Androstenedione and testosterone were the main androgens detected in all effluents. High removal efficiency (91-100%) was found for androgens and progestogens compared with estrogens (67-80%), with biodegradation the major removal route in WWTPs. Different profiles of progestogens in the receiving rivers and WWTP effluents were observed, which could be explained by the discharge of a mixture of treated and untreated wastewater into the receiving rivers.     

Occurrence, partition and removal of pharmaceuticals in sewage water and sludge during wastewater treatment

During 8 sampling campaigns carried out over a period of two years, 72 samples, including influent and effluent wastewater, and sludge samples from three conventional wastewater treatment plants (WWTPs), were analyzed to assess the occurrence and fate of 43 pharmaceutical compounds. The selected pharmaceuticals belong to different therapeutic classes, i.e. non-steroidal anti-inflammatory drugs, lipid modifying agents (fibrates and statins), psychiatric drugs (benzodiazepine derivative drugs and antiepileptics), histamine H2-receptor antagonists, antibacterials for systemic use, beta blocking agents, beta-agonists, diuretics, angiotensin converting enzyme (ACE) inhibitors and anti-diabetics. The obtained results showed the presence of 32 target compounds in wastewater influent and 29 in effluent, in concentrations ranging from low ng/L to a few μg/L (e.g. NSAIDs). The analysis of sludge samples showed that 21 pharmaceuticals accumulated in sewage sludge from all three WWTPs in concentrations up to 100 ng/g. This indicates that even good removal rates obtained in aqueous phase (i.e. comparison of influent and effluent wastewater concentrations) do not imply degradation to the same extent. For this reason, the overall removal was estimated as a sum of all the losses of a parent compound produces by different mechanisms of chemical and physical transformation, biodegradation and sorption to solid matter. The target compounds showed very different removal rates and no logical pattern in behaviour even if they belong to the same therapeutic groups. What is clear is that the elimination of most of the substances is incomplete and improvements of the wastewater treatment and subsequent treatments of the produced sludge are required to prevent the introduction of these micro-pollutants in the environment.     

Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China

The occurrence and removal of 13 pharmaceuticals and 2 consumer products, including antibiotic, antilipidemic, anti-inflammatory, anti-hypertensive, anticonvulsant, stimulant, insect repellent and antipsychotic, were investigated in four wastewater treatment plants (WWTPs) of Beijing, China. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Most of the target compounds were detected, with the concentrations of 4.4 ng L⁻¹-6.6 μg L⁻¹ and 2.2-320 ng L⁻¹ in the influents and secondary effluents, respectively. These concentrations were consistent with their consumptions in China, and much lower than those reported in the USA and Europe. Most compounds were hardly removed in the primary treatment, while their removal rates ranging from −12% to 100% were achieved during the secondary treatment. In the tertiary treatment, different processes showed discrepant performances. The target compounds could not be eliminated by sand filtration, but the ozonation and microfiltration/reverse osmosis (MF/RO) processes employed in two WWTPs were very effective to remove them, showing their main contributions to the removal of such micro-pollutants in wastewater treatment.     

Pathways and metabolites of microbial degradation of selected acidic pharmaceutical and their occurrence in municipal wastewater treated by a membrane bioreactor

Laboratory degradation tests with five acidic pharmaceuticals using activated sludge as inocculum under aerobic conditions were performed and microbial metabolites were analysed by liquid chromatography-mass spectrometry (LC-MS). Ketoprofen was partly mineralized as a sole source of carbon and energy and the metabolites determined by LC-MS suggest microbial ketoprofen degradation to proceed along the pathway known for biphenyls and related compounds. Bezafibrate, naproxen and ibuprofen were degraded only cometabolically whereas no transformation was obtained for diclofenac. Some biodegradation intermediates in these batch tests could be tentatively identified by means of LC-MS. The first step in microbial bezafibrate degradation appears to be the hydrolytic cleavage of the amide bond, generating well degradable 4-chlorobenzoic acid as one of the hydrolysis products. As previously found for mammals, ether cleavage and formation of desmethylnaproxen was the initial step in microbial degradation of naproxen. Two isomers of hydroxy-ibuprofen were detected as intermediates in the mineralization of ibuprofen. Laboratory studies suggest that naproxen and ibuprofen can be fully mineralized whereas more stable metabolites occur in microbial ketoprofen and bezafibrate transformation, that may deserve further attention. A LC-MS method for the trace analysis of these metabolites in water was developed and applied to municipal wastewater. Municipal wastewater treatment by a membrane bioreactor may gradually improve the removal of these pharmaceuticals.     

Fate of physical,chemical, and microbial contaminants in domestic wastewater following treatment by small constructed wetlands

In order to evaluate the efficacy of constructed wetlands for treatment of domestic wastewater for small communities located in rural areas, small-scale wetland mesocosms (400 L each) containing two treatment designs (a mixture of Typha, Scirpus, and Juncus species; control without vegetation) were planted into two depths (45 or 60 cm) with pea gravel. Each mesocosm received 19 L/day of primary-treated domestic sewage. Mesocosms were monitored (inflow and outflow samples) on a monthly basis over a 2-year period for pH, total suspended solids (TSS), 5-day biochemical oxygen demand (BOD(5)), total Kjeldahl nitrogen (TKN), dissolved oxygen (DO), and conductivity. Microbiological analyses included enumeration of fecal coliforms, enterococci, Salmonella, Shigella, Yersinia, and coliphage. Significant differences between influent and effluent water quality for the vegetated wetlands (p<0.05) were observed in TSS, BOD(5), and TKN. Increased DO and reduction in fecal coliform, enterococcus, Salmonella, Shigella, Yersinia, and coliphage populations also were observed in vegetated wetlands. Greatest microbial reductions were observed in the planted mesocosms compared to those lacking vegetation. Despite marked reduction of several contaminants, wetland-treated effluents did not consistently meet final discharge limits for receiving bodies of water. Removal efficiencies for bacteria and several chemical parameters were more apparent during the initial year compared to the second year of operation, suggesting concern for long-term efficiency and stability of such wetlands.     

Data evaluation of full-scale wastewater treatment plants by mass balance

Measured data of wastewater treatment plants (WWTPs) often contains errors. These errors can prohibit the use of WWTP data for process evaluation, process design, benchmarking or modelling purposes. In this paper a practical stepwise methodology is presented to check WWTP data using mass balances. The presented results show that poor WWTP data quality leads to large errors when calculating key operational conditions such as the solids retention time (SRT), oxygen consumption (OC) and the different internal conversions rates. By improving WWTP data quality using mass balance calculations useful new information becomes available for process evaluation, WWTPs design and benchmarking.     

Effects of design flow and treatment level on construction and operation costs of municipal wastewater treatment plants and their implications on policy making

Construction costs of 55 municipal wastewater treatment plants in Israel (secondary, advanced secondary, and advanced treatment) were analysed in order to derive cost functions expressing the effects of design flow and treatment level on construction costs. Three equations were derived (statistically significant, p<0.01), one for each treatment level. These indicate that economy of scale may become weaker as treatment level rises. Analysis of the distribution of construction costs revealed negative correlation (p<0.05) between the proportional cost of civil engineering and design flow, positive correlation (p<0.05) between the proportional cost of elecromechanical equipment and design flow, and no correlation between the proportional cost of electricity and control and design flow. Operation costs were found to be 20–70% more sensitive than construction costs to treatment level. The share of operation costs as part of the total annual costs was found to increase both with design flow and treatment level, whereas the share of construction costs concurrently decreased. The implication of the findings on policy, and consequently on treatment plants performance is discussed in the last part of the paper.     

Site-related airborne biological hazard and seasonal variations in two wastewater treatment plants

Results of a study conducted to assess the degree of airborne bacterial contamination generated by two wastewater treatment plants (WWTP) with different treatment systems and evaluate the dispersion of potential pathogens, have been described. Aerosols samples were collected in summer and winter with an agar impact sampler from several plant sites. External upwind and downwind controls were also examined. Total colony-forming counts of mesophilic and thermophilic bacteria, actinomycetes and streptomycetes, Gram-negatives, coliforms and sulfite-reducers were determined. Selective media were used in order to detect pathogenic bacteria. The lowest concentrations of mesophilic and thermophilic bacteria were 8 and 28 CFU/m(3) in plants A and B respectively, the highest >40,000 CFU/m(3) in both plants. Strains of Escherichia coli, Clostridium perfringens, Staphylococcus aureus and Enterococcus spp. were isolated in some sites of the two plants. Salmonella spp., Yersinia enterocolitica and Legionella spp. were never detected. The activities involving nebulization and mechanical aeration of wastewaters and the sewage inflows have proved to be of greatest potential risk. In both plants, we found a statistically significant dependence of bacterial contamination on the season for many of the analyzed parameters but a clear seasonal trend could not be observed.     

Occurrence and removal of N-nitrosamines in wastewater treatment plants

The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 μg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage. Aqueous removal efficiencies in activated sludge treatment were in general above 40% for NMOR and above 60% for the other nitrosamines, but could be lower if concentrations were below 8-15 ng/L in primary effluent. We hypothesize that substrate competition in the cometabolic degradation explains the occurrence of such threshold concentrations. An additional sand filtration step resulted in a further removal of nitrosamines from secondary effluents even at low concentrations. Concentrations released to surface waters were largely below 10 ng/L, suggesting a low impact on Swiss water resources and drinking water generation considering the generally high environmental dilution and possible degradation. However, local impacts in case a larger fraction of wastewater is present cannot be ruled out.     

Occurrence and removal of antibiotics, hormones and several other pharmaceuticals in wastewater treatment plants of the largest industrial city of Korea

Occurrence and removal efficiencies of 20 pharmaceuticals and personal care products (PPCPs) including antibiotics, hormones, and several other miscellaneous pharmaceuticals (analgesics, antiepileptics, antilipidemics, antihypertensives, antiseptics, and stimulants) were investigated in five wastewater treatment plants (WWTPs) of Ulsan, the largest industrial city of Korea. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The results showed that acetaminophen, atenolol and lincomycin were the main individual pollutants usually found in concentrations over 10 μg/L in the sewage influent. In the WWTPs, the concentrations of analgesic acetaminophen, stimulant caffeine, hormones estriol and estradiol decreased by over 99%. On the contrary, the antibiotic sulfamethazine, the antihypertensive metoprolol, and the antiepileptic carbamazepine exhibited removal efficiencies below 30%. Particularly, removal of antibiotics was observed to vary between − 11.2 and 69%. In the primary treatment (physico-chemical processes), the removal of pharmaceuticals was insignificant (up to 28%) and removal of majority of the pharmaceuticals occurred during the secondary treatment (biological processes). The compounds lincomycin, carbamazepine, atenolol, metoprolol, and triclosan showed better removal in WWTPs employing modified activated sludge process with co-existence of anoxic-oxic condition. Further investigation into the design and operational aspects of the biological processes is warranted for the efficient removal of PPCPs, particularly antibiotics, to secure healthy water resource in the receiving downstream, thereby ensuring a sustainable water cycle management.     

Antimicrobial resistance of fecal indicators in municipal wastewater treatment plant

Antimicrobial resistance of fecal coliforms (n = 153) and enterococci (n = 199) isolates was investigated in municipal wastewater treatment plant (WWTP) based on activated sludge system. The number of fecal indicators (in influent and effluent as well as in the aeration chamber and in return activated sludge mixture) was determined using selective media. Susceptibility of selected strains was tested against 19 (aminoglycosides, aztreonam, carbapenems, cephalosporins, β-lactam/β-lactamase inhibitors, fluoroquinolones, penicillines, tetracycline and trimethoprim/sulfamethoxazole) and 17 (high-level aminoglycosides, ampicillin, chloramphenicol, erythromycin, fluoroquinolones, glycopeptides, linezolid, lincosamides, nitrofuration, streptogramins, tetracycline) antimicrobial agents respectively. Among enterococci the predominant species were Enterococcus faecium (60.8%) and Enterococcus faecalis (22.1%), while remaining isolates belonged to Enterococcus hirae (12.1%), Enterococcus casseliflavus/gallinarum (4.5%), and Enterococcus durans (0.5%). Resistance to nitrofuration and erythromycin was common among enterococci (53% and 44%, respectively), and followed by resistance to ciprofloxacin (29%) and tetracycline (20%). The resistance phenotypes related to glycopeptides (up to 3.2%) and high-level aminoglycosides (up to 5.4%) were also observed. Most frequently, among Escherichia coli isolates the resistance patterns were found for ampicillin (34%), piperacillin (24%) and tetracycline (23%). Extended-spectrum β-lactamase producing E. coli was detected once, in the aeration chamber. In the study the applied wastewater treatment processes considerably reduced the number of fecal indicators. Nevertheless their number in the WWTP effluent was higher than 10⁴ CFU per 100 ml and periodically contained 90% of bacteria with antimicrobial resistance patterns. The positive selection of isolates with antimicrobial resistance patterns was observed during the treatment processes. Substantial concern should be paid to the isolates resistant to 3 or more chemical classes of antimicrobials (MAR). In treated wastewater MAR E. coli and MAR enterococci constituted respectively 9% and 29% of tested isolates.     

Persistence and prevalence of pathogenic and extended-spectrum beta-lactamase-producing Escherichia coli in municipal wastewater treatment plant receiving slaughterhouse wastewater

We compared the prevalence of pathogenic and extended-spectrum beta-lactamase (ESBL) – producing Escherichia coli in effluents of a municipal wastewater treatment plant (WWTP) receiving wastewater from a slaughterhouse. A total of 1248 isolates were screened for the presence of virulence genes associated with enterohemorrhagic E. coli (EHEC) (stx₁, stx₂, and eae) and extraintestinal pathogenic E. coli (ExPEC) (sfa/focDE, kpsMT K1, hlyA, papEF, afa/draBC, clbN, f17A and cnf). The prevalence of atypical enteropathogenic E. coli (EPEC) was 0.7%, 0.2% and 0.5% in city wastewater, slaughterhouse wastewater and in the treated effluent, respectively. One stx_1a and stx_2b-positive E. coli isolate was detected in city wastewater. The prevalence of ExPEC was significantly higher in city wastewater (8.4%), compared to slaughterhouse wastewater (1.2%). Treatment in the WWTP did not significantly impact the prevalence of ExPEC in the outlet effluent (5.0%) compared to city wastewater. Moreover, the most potentially pathogenic ExPEC were isolated from city wastewater and from the treated effluent. ESBL-producing E. coli was also mainly detected in city wastewater (1.7%), compared to slaughterhouse wastewater (0.2%), and treated effluent (0.2%). One ESBL-producing E. coli, isolated from city wastewater, was eae-β1 positive. These results showed that pathogenic and/or ESBL-producing E. coli were mainly detected in human wastewater, and at a lesser extend in animal wastewater. Treatment failed to eliminate these strains which were discharged into the river, and then these strains could be transmitted to animals and humans via the environment.     

Occurrence of emerging pollutants in urban wastewater and their removal through biological treatment followed by ozonation

This work reports a systematic survey of over seventy individual pollutants in a Sewage Treatment Plant (STP) receiving urban wastewater. The compounds include mainly pharmaceuticals and personal care products, as well as some metabolites. The quantification in the ng/L range was performed by Liquid Chromatography-QTRAP-Mass Spectrometry and Gas Chromatography coupled to Mass Spectrometry. The results showed that paraxanthine, caffeine and acetaminophen were the main individual pollutants usually found in concentrations over 20 ppb. N-formyl-4-amino-antipiryne and galaxolide were also detected in the ppb level. A group of compounds including the beta-blockers atenolol, metoprolol and propanolol; the lipid regulators bezafibrate and fenofibric acid; the antibiotics erythromycin, sulfamethoxazole and trimethoprim, the antiinflammatories diclofenac, indomethacin, ketoprofen and mefenamic acid, the antiepileptic carbamazepine and the antiacid omeprazole exhibited removal efficiencies below 20% in the STP treatment. Ozonation with doses lower than 90 μM allowed the removal of many individual pollutants including some of those more refractory to biological treatment. A kinetic model allowed the determination of second order kinetic constants for the ozonation of bezafibrate, cotinine, diuron and metronidazole. The results show that the hydroxyl radical reaction was the major pathway for the oxidative transformation of these compounds.     

Removal of selected pharmaceuticals, fragrances and endocrine disrupting compounds in a membrane bioreactor and conventional wastewater treatment plants

Eight pharmaceuticals, two polycyclic musk fragrances and nine endocrine disrupting chemicals were analysed in several waste water treatment plants (WWTPs). A membrane bioreactor in pilot scale was operated at different solid retention times (SRTs) and the results obtained are compared to conventional activated sludge plants (CASP) operated at different SRTs. The SRT is an important design parameter and its impact on achievable treatment efficiencies was evaluated. Different behaviours were observed for the different investigated compounds. Some compounds as the antiepileptic drug carbamazepine were not removed in any of the sampled treatment facilities and effluent concentrations in the range of influent concentrations were measured. Other compounds as bisphenol-A, the analgesic ibuprofen or the lipid regulator bezafibrate were nearly completely removed (removal rates >90%). The operation of WWTPs with SRTs suitable for nitrogen removal (SRT>10 days at 10 degrees C) also increases the removal potential regarding selected micropollutants. No differences in treatment efficiencies were detected between the two treatment techniques. As in conventional WWTP also the removal potential of MBRs depends on the SRT. Ultrafiltration membranes do not allow any additional detention of the investigated substances due to size exclusion. However, MBRs achieve a high SRT within a compact reactor. Nonylphenolpolyehtoxylates were removed in higher extend in very low-loaded conventional WWTPs, due to variations of redox conditions, necessary for the degradation of those compounds.