Wastewater Treatment Plant Outlet Research Articles

Characterization of fecal indicator bacteria in sediments cores from the largest freshwater lake of Western Europe (Lake Geneva, Switzerland)

This study characterized the fecal indicator bacteria (FIB), including Escherichia coli (E. coli) and Enteroccocus (ENT), disseminated over time in the Bay of Vidy, which is the most contaminated area of Lake Geneva. Sediments were collected from a site located at ∼500m from the present waste water treatment plant (WWTP) outlet pipe, in front of the former WWTP outlet pipe, which was located at only 300m from the coastal recreational area (before 2001). E. coli and ENT were enumerated in sediment suspension using the membrane filter method. The FIB characterization was performed for human Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) and human specific bacteroides by PCR using specific primers and a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Bacterial cultures revealed that maximum values of 35.2×108 and 6.6×106CFUg−1 dry sediment for E. coli and ENT, respectively, were found in the sediments deposited following eutrophication of Lake Geneva in the 1970s, whereas the WWTP started operating in 1964. The same tendency was observed for the presence of human fecal pollution: the percentage of PCR amplification with primers ESP-1/ESP-2 for E. faecalis and E. faecium indicated that more than 90% of these bacteria were from human origin. Interestingly, the PCR assays for specific-human bacteroides HF183/HF134 were positive for DNA extracted from all isolated strains of sediment surrounding WWPT outlet pipe discharge. The MALDI-TOF MS confirmed the presence of general E. coli and predominance E. faecium in isolated strains. Our results demonstrated that human fecal bacteria highly increased in the sediments contaminated with WWTP effluent following the eutrophication of Lake Geneva. Additionally, other FIB cultivable strains from animals or adapted environmental strains were detected in the sediment of the bay. The approaches used in this research are valuable to assess the temporal distribution and the source of the human fecal pollution in aquatic environments.

Determination of atrazine in surface waters by combination of POCIS passive sampling and ELISA detection

Polar organic compound integrative samplers (POCIS) in combination with instrumental techniques such as LC-MS-MS were previously used to monitor environmental pollutants but the performance of alternative immunochemical methods such as ELISA (enzyme-linked immunosorbent assay) has been explored less. In the present study, POCIS technology was applied to surface water sampling in the Czech Republic, and ELISA was used as a detection technique for the herbicide atrazine. In the first study, 28 samples from streams around small municipal waste water treatment plants (WWTPs) were collected using two different devices (POCISpest and POCISpharm) over the course of 21 days. Elevated atrazine concentrations (up to 25 ng per POCIS) were found in samples down-stream of WWTPs. This observation was also confirmed in another two year study (4 sampling periods) investigating 7 river sites around a major city of Brno as well as the inlet and outlet of the city's WWTP. High atrazine levels were systematically determined at the outlet from the WWTPs (120-605 ng per POCIS). A decreasing trend in the atrazine concentrations in rivers around the city of Brno has been observed, with the highest levels observed within the first sampling period in spring 2007 (100-600 ng per POCIS, with an extreme value of 2760 ng per POCIS). Results of the atrazine ELISA were closely correlated with LC-MS/MS, which confirmed good applicability of ELISA as a cost-effective screening tool.

Seasonal changes in the concentration of anionic surfactants in estuarine sediments from the River Guadalete (Cadiz, Spain)

The presence and longitudinal and temporal distributions of the two main anionic surfactants, linear alkylbenzene sulfonates (LAS) and alkyl ethoxysulfates (AES), were monitored in surface sediments from the Guadalete estuary, located in the north of the Bay of Cadiz (SW of Spain). Seasonal samplings were performed for two years at three different stations; one of them located up-stream near the discharge outlet of a wastewater treatment plant (WWTP). A control station was also sampled in a tidal channel within the boundaries of a natural park adjacent to the estuary. LAS and AES concentration values ranged from 196 to 2864 ng g -1 and from 147 to 557 ng g -1 , respectively, the lowest values corresponding to the control station and the highest ones found near the WWTP outlet. A general decrease in the concentrations of both surfactants was found in summer, when degradation processes are faster, whereas the highest concentrations were detected during the wet months, when temperature decreases and rainwater exceeds the WWTP capacity, so untreated wastewater is discharged directly into the river. Due to differential sorption and degradation processes, the relative distribution of LAS homologues in sediments showed higher percentages for those having longer alkyl chains, whereas AES homologues with an even carbon unit number in the alkyl chain and AES ethoxymers with fewer ethylene groups were predominant. No hazard for aquatic organisms was foreseen at the concentrations found for both surfactants along the estuary.

Occurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland. Part II: Micropollutant removal between wastewater and raw drinking water

The occurrence and removal of 58 pharmaceuticals, endocrine disruptors, corrosion inhibitors, biocides, and pesticides, were assessed in the wastewater treatment plant (WWTP) of the city of Lausanne, Switzerland, as well as in the effluent-receiving water body, the Vidy Bay of Lake Geneva. An analytical screening method to simultaneously measure all of the 58 micropollutants was developed based on ultra performance liquid chromatography coupled to a tandem mass spectrometer (UPLC-MS/MS). The selection of pharmaceuticals was primarily based on a prioritization study, which designated them as environmentally relevant for the Lake Geneva region. Except for the endocrine disruptor 17alpha-ethinylestradiol, all substances were detected in 24-h composite samples of wastewater entering the WWTP or in the treated effluent. Of these compounds, 40% were also detected in raw drinking water, pumped from the lake 3 km downstream of the WWTP. The contributions of dilution and degradation to micropollutant elimination between the WWTP outlet and the raw drinking water intake were established in different model scenarios using hypothetical residence times of the wastewater in Vidy Bay of 1, 4, or 90 d. Concentration decrease due to processes other than dilution was observed for diclofenac, beta-blockers, several antibiotics, corrosion inhibitors, and pesticides. Measured environmental concentrations (MECs) of pharmaceuticals were compared to the predicted environmental concentrations (PECs) determined in the prioritization study and agreed within one order of magnitude, but MECs were typically greater than the corresponding PECs. Predicted no-effect concentrations of the analgesic paracetamol, and the two antibiotics ciprofloxacin and sulfamethoxazole, were exceeded in raw drinking water samples and therefore present a potential risk to the ecosystem.

Automated Determination of Linear Alkylbenzene Sulphonate (LAS) in Wastewater Treatment Plants Effluents Using on Line Solid-phase Extraction Followed by HPLC with Fluorescence Detection

Abstract An on line SPE (solid-phase extraction) method followed by HPLC with fluorescence detection has been developed and validated for determining the LAS in inlet and outlet effluents of wastewaters treatment plants. Filtered effluent samples were on line concentrated on a small polymeric reversed phase column, then the trapped LAS are separated on a specialty polar-embedded reversed-phase column and detected by a fluorimeter. The on line SPE method with fluorescence detection showed very good repeatability (from 1.5 to 11.7% depending on the sample loading volume) and robustness with detection limits of 1.5 μg l−1 for total C10–13 LAS loading a 5 ml sample volume. This automated method is a cost-effective way to determine LAS also in routine monitoring of inlets and outlets of wastewater treatment plants allowing to optimize treatment procedures.

Distribution and survival of faecal indicator bacteria in the sediments of the Bay of Vidy, Lake Geneva, Switzerland

The purpose of this study was to determine the concentrations and the horizontal distribution of faecal indicator bacteria (FIB) including Escherichia coli and Enterococcus sp. in the bottom sediments of the Bay of Vidy, City of Lausanne, Switzerland. A vertical distribution of FIB in sediments near the municipal wastewater treatment plant (WWTP) outlet was evaluated and their persistence in those sediments was monitored for a period of 90 days. High FIB levels were measured in the sediments sampled near the WWTP outlet pipe and the mouth of the Chamberonne River, at concentrations ranging between 105 and 107 CFU 100 g−1. FIB levels at 10 cm depth in the sediments near the WWTP outlet pipe ranged between 104 and 105 CFU 100 g−1, and were still detected in the top 6 cm after 90 days. Results of this study indicate that freshwater sediments of the Bay of Vidy constitute a reservoir of faecal indicator bacteria, which can persist in certain areas of the bay. Possible resuspension of FIB and pathogens may affect water quality and may increase health risks to sensitive populations during recreational activities. FIB survival in sediments for long periods is of considerable significance for the understanding of microbial pollution in water and for the management of risk at specific recreational coastal sites.

Origin and spatial–temporal distribution of faecal bacteria in a bay of Lake Geneva, Switzerland

The origin and distribution of microbial contamination in Lake Geneva's most polluted bay were assessed using faecal indicator bacteria (FIB). The lake is used as drinking water, for recreation and fishing. During 1 year, water samples were taken at 23 points in the bay and three contamination sources: a wastewater treatment plant (WWTP), a river and a storm water outlet. Analyses included Escherichia coli, enterococci (ENT), total coliforms (TC), and heterotrophic plate counts (HPC). E. coli input flux rates from the WWTP can reach 2.5 x 10(10) CFU/s; those from the river are one to three orders of magnitude lower. Different pathogenic Salmonella serotypes were identified in water from these sources. FIB levels in the bay are highly variable. Results demonstrate that (1) the WWTP outlet at 30 m depth impacts near-surface water quality during holomixis in winter; (2) when the lake is stratified, the effluent water is generally trapped below the thermocline; (3) during major floods, upwelling across the thermocline may occur; (4) the river permanently contributes to contamination, mainly near the river mouth and during floods, when the storm water outlet contributes additionally; (5) the lowest FIB levels in the near-surface water occur during low-flow periods in the bathing season.

Myocarditis: An expected health hazard associated with water resources contaminated with Coxsackie viruses type B

Enteroviruses, especially Coxsackie B viruses (CBVs), are responsible for approximately 50% of cases of viral myocarditis. In the present study, serum samples (160) were collected from acute myocarditis patients at different age groups and 104 samples of the same age groups as a control. Cholesterol, LDH, CPK, and GOT were measured for all serum samples (264). Also, to study the source of virus transmission, 72 water and 72 wastewater samples were collected from water and wastewater treatment plants at intakes and outlets. Water and wastewater samples were concentrated by filtration through Zeta-plus filter cartridges and reconcentrated by the PEG-6000 precipitation method. Serum, water, and wastewater samples were inoculated in BGM cells for three successive passages. RT - PCR with enterovirus primers was carried out directly for serum samples and for 1st and 3rd cell culture passages. The positive samples were used for neutralization assay using anti-CBV sera pool to determine the CBV followed by neutralization with separate antisera. The results showed that 50 (31.25%) serum samples from acute myocarditis patients and two (1.4%) samples from the controls were positive for enterovirus RT - PCR. For water and wastewater samples enteroviruses were present in 63.8% and 8.3% for intake and outlet of water treatment plants and, 66.6% and 47.2% for intake and outlet of wastewater treatment plants, respectively. The level of CBV serotypes was varied where CBV3 was dominant for all age groups of myocarditis patients and CBV2 and CBV5 were also detected while CBV2 was the main CBV in water samples and CBV2, 3 and 5 were detected in wastewater samples. The integration of cell culture-PCR reduces the time required for virus detection and enhances the sensitivity of the test.

Impact of an urban centre on the nitrogen cycle processes of epilithic biofilms during a summer low‐water period *

AbstractNitrogen transformations in epilithic biofilms of a large gravel bed river, the Garonne, France, has been studied upstream (one site) and downstream (four sites) of a large urban centre (Toulouse, 740 000 inhabitants).High biomass, up to 49 g AFDM m−2 (ashes free dry matter) and 300 mg chlorophyll a m−2 (Chl. a), were recorded at 6 and 12 km downstream from the main wastewater treatment plant outlet. The lowest records upstream and larger downstream (less than 16 g AFDM m−2 or 120 mg Chl. a m−2) could be explained by recent water fall (early summer low‐water period).Measurements of nitrogen exchange at the biofilm–overlying water interface were performed in incubation chambers under light and dark conditions. The addition of acetylene at the mid‐incubation time allowed evaluation of both nitrification (variation in NH4+ flux after the ammonium monooxygenase inhibition) and denitrification (N2O accumulation related to the inhibition of N2O reduction). Denitrification (Dw) and nitrification rates were maximum at sites close to the city discharges in dark conditions (up to 9.1 and 5.6 mg N m−2 h−1, respectively). Unexpected denitrification activities in light conditions (up to 1.4 mg N m−2 h−1) at these sites provided evidence for enhanced nitrogen self‐purification downstream.As confirmed by most probable number (MPN) counts, high nitrification rates in biofilm close downstream were related to enhanced (more than almost 3 log) nitrifying bacteria densities (up to 7.6×109 MPN m−2). Downstream of an urban centre, nitrogen transformations in the biofilm appeared to be influenced by the occurrence of an adapted microflora which is inoculated or stimulated by anthropic pollution. Copyright © 2002 John Wiley & Sons, Ltd.

Impact of an urban centre on the nitrogen cycle processes of epilithic biofilms during a summer low-water period This paper arose from the Eighth International Symposium on Regulated Streams (EISORS).*

Nitrogen transformations in epilithic biofilms of a large gravel bed river, the Garonne, France, has been studied upstream (one site) and downstream (four sites) of a large urban centre (Toulouse, 740 000 inhabitants). High biomass, up to 49 g AFDM m−2 (ashes free dry matter) and 300 mg chlorophyll a m−2 (Chl. a), were recorded at 6 and 12 km downstream from the main wastewater treatment plant outlet. The lowest records upstream and larger downstream (less than 16 g AFDM m−2 or 120 mg Chl. a m−2) could be explained by recent water fall (early summer low-water period). Measurements of nitrogen exchange at the biofilm–overlying water interface were performed in incubation chambers under light and dark conditions. The addition of acetylene at the mid-incubation time allowed evaluation of both nitrification (variation in NH4+ flux after the ammonium monooxygenase inhibition) and denitrification (N2O accumulation related to the inhibition of N2O reduction). Denitrification (Dw) and nitrification rates were maximum at sites close to the city discharges in dark conditions (up to 9.1 and 5.6 mg N m−2 h−1, respectively). Unexpected denitrification activities in light conditions (up to 1.4 mg N m−2 h−1) at these sites provided evidence for enhanced nitrogen self-purification downstream. As confirmed by most probable number (MPN) counts, high nitrification rates in biofilm close downstream were related to enhanced (more than almost 3 log) nitrifying bacteria densities (up to 7.6×109 MPN m−2). Downstream of an urban centre, nitrogen transformations in the biofilm appeared to be influenced by the occurrence of an adapted microflora which is inoculated or stimulated by anthropic pollution. Copyright © 2002 John Wiley & Sons, Ltd.

UV-disinfection of treated wastewater: possible effects on surface waters

UV-irradiation as an effective method of diminishing germs in the outlet of wastewater treatment plants was studied in a half-scale pilot-project sponsored by the State of Bavaria/BRD for a period of 3 years. Technical, physical and biological parameters capable of influencing this process were examined. The possibility to improve the hygienic and also the ecological structure of receiving waters was put to discussion. Possible effects of formed bypproducts upon the water biocoenosis of rivers were pointed out. The results demonstrated that UV-irradiation can diminish the number of germs in the outlet of a treatment plant to an extent which is sufficient to guarantee the maintenance of the bacteriological and presumably also the virological values set by the EC Bathing Water Directive. Nevertheless the UV-treatment process requires further technological development and research work concerning i.e. the improvement of hydraulic conditions, coat-forming on the quartz sleeves of the lamps, photochemical forming of by-products, after-growth and effects upon the localised benthic flora and fauna of the receiving water. It has to be stressed that a significant improvement of the bacteriological structure of flowing waters is only attainable, if the influx from non-point sources can be reduced simultaneously.

Survey of trihalomethane levels in Rhône-Alps water supplies. Estimates on the formation of chloroform in wastewater treatment plants and swimming pools

A survey undertaken in the Rhône-Alps region has shown that haloforms occurred in various water samples. Drinking water contained very low levels of haloforms. Whereas surface water and water at the outlet of wastewater treatment plants had significantly higher haloforms levels, both around 6 times more than drinking water. As for swimming pools, where high levels of haloforms were found, there is a possibility that some metabolites of human origin, such as citric acid and dihydroxybenzoic acid, might serve as precursors.