Participatory research to monitor lake water pollution

A participatory research team, concerned about water quality around Lake Geneva, particularly in the Montreux Bay region where some were lifeguards, ran sampling campaigns to determine summertime levels of lake water pollution. The participants were brought together serendipitously through a course organized by academic researchers and 'biohackers' from the community laboratory, Hackuarium. After discussion about lifeguards' gastrointestinal and dermatological ailments each season, the decision to pursue this participatory research project was made. In order to assess water quality, thereby testing the hypothesis that unsuspected pollution enters the lake each summer season, microbiological plating of water samples was proposed. Volunteers collected and analysed water samples over summer seasons (8 weeks in 2016, 2017 and 2020) from three sites around Montreux Bay, with tap and local river water samples as controls. Contamination of lake water was measured using standard microbiological methods, with growth media allowing quantitative assessment of abundance of several bacterial species. In particular, the focus was to quantify Escherichia coli, the classic bioindicator organism for raw sewage contamination. These open science data reveal peaks of bioindicator and other bacterial pollution in lake water samples during all sampling years. For the initial two sampling campaigns, increased microbial burdens occurred during a popular music festival, and were not simply dependent upon rainfall. In contrast, only scattered, lower level bioindicator pollution events occurred across the sampling period during the pandemic summer of 2020, when the festival was cancelled. This study confirms the power of participatory research: dedicated people on a budget can do meaningful environmental monitoring. These analyses suggest that better management, both to support water quality monitoring and for event organization, is essential, as sewage treatment facilities near many popular festivals, internationally, may need to cope with increased wastewater from visitors.

Sources, Spreading and Fate of Antibiotic Resistance Genes and Resistant Bacteria in Vidy Bay, Lake Geneva, Switzerland

Nadine Czekalski

Increasing numbers of multiresistant bacterial pathogens cause severe health problems on a global scale. Large quantities of bacteria and their resistance genes are discharged into natural environments via human and animal waste. Not much is known so far about the fate and further spread of resistance determinants in the environment. There is evidence that aquatic environments may function as important compartments for preserving and exchanging antibiotic resistance genes (ARG) from sewage and drinking water. Lake Geneva is the largest fresh water reservoir of Western Europe and supplies the surrounding cities. At the same time these cities discharge sewage into the lake. Lausanne is the largest city in the lake’s catchment and discharges the highest amount of treated, as well as in case of heavy rain events, partly untreated waste waters. Also two rivers, Chambering and Flown, transport untreated sewage (bypass), in case of storm events. Only 3.4 km from the sewage discharge point lake water is pumped for drinking water preparation for Lausanne. Many studies have reported on contamination of the bay with heavy metals, inorganic nutrients, organic carbon and fecal indicator bacteria due to the sewage discharge. The present thesis aimed on investigating the sources, spreading and fate of antibiotic resistant bacteria and antibiotic resistance genes in the Vida bay, Lake Geneva. In the first part of this dissertation, a screening for antibiotic- and specifically multi-resistant bacteria was carried out as one of the first studies in a Swiss waste water stream and the receiving fresh water lake. For this purpose, a combined set of culture based (viable bacterial counts on nutrient media supplemented with antibiotics) and molecular tools (detection and quantitation of antibiotic resistance genes from environmental DNA-extracts using quantitative real-time PCR) was applied. Raw hospital and communal sewage, as well as partly treated/mixed sewage, which is discharged into the lake via an effluent pipe 700 m off shore, were taken into account. Furthermore lake water samples nearby the end of the waste water discharge pipe and the drinking water pump as well as close to the two river mouths were analyzed. Finally, the role of Lausannes WTP was evaluated for its potential to remove resistant and multiresistant bacteria, as well ARG. Results show highest levels of multiresistant bacteria and ARG in both hospital and communal sewage. Incidence was found that the WTP is a selective environment for multiresistant bacteria and resistance genes. Moreover, lake water and sediments nearby the end of the WTP discharge pipe and the two river mouths exhibited significantly higher levels of resistant determinants as compared to samples from the drinking water uptake. If the level of antibiotic resistance close to the drinking water uptake represents the natural background level of the lake or whether it is impacted by the WTP plume remained open during this first survey. The spatial distribution and persistence of ARG discharged via waste water into lake systems has been evaluated for the first time in the second part of this thesis. 22 sediment cores were sampled along two major transects (leading either into the deep lake or along the south-western shore line to the drinking water uptake) and in the vicinity of the WTP discharge pipe in the Vidy bay. A subset of samples was also analyzed for contamination with a “conventional” pollutant of sewage (mercury), for which a similar transport behavior (particle bound) as for bacteria and their resistance genes is assumed. The microbial community composition in all sediment as well as in waste water samples was analyzed using ARISA. Strong pollution with both ARG and mercury was detected in close proximity of the WTP discharge pipe and both contaminants significantly decreased along the transect into the deep lake. In general however, the spatial contamination of mercury and ARG was only moderately correlated. While the mercury contaminated sediment surface area tended to have a pollution tail in south eastern direction, ARG showed only a slow decrease along the south western transect. These findings imply differences in transport and fate of mercury and ARG in the bay, or additional sources of ARG contamination. Analysis of the microbial diversity in the samples support these hypotheses. This study revealed feasibility of qPCR as a tool to semi-quantitatively track spatial ARG contamination in fresh water lake sediments. Not much is known yet on the antibiotic resistance background level of fresh water lakes and how this may be influenced by anthropogenic activities in the surrounding catchment. Water samples from 21 Swiss lakes have been collected and were analyzed for the prevalence of different ARG (2 sulfonamide resistance genes sul1 & sul2, 3 tetracycline resistance genes tetB, tetM, tetW and one plasmid mediated fluoroquinolone resistance gene qnrA). In order to document the abundance of these genes in the bacterial populations, they were normalized to bacterial 16S rRNA gene copy numbers. The lakes differ in size, geographical position, land use pattern, and trophical status. The composition of the microbial community of all lakes was analyzed using ARISA. Sulfonamide resistance genes were detected in all investigated lakes (0.2-4%, sul1 and 0.01-0.3%, sul2), with highest levels in Lake Baldegger (21%). Lake Baldegger also contained all of the three tetracycline resistance genes, which were found in only 4 other lakes. None of the lakes was positive for qnrA. Important anthropogenic catchment activities linked to sul gene prevalence could not be identified based on our data and may require further analysis and an additional variables to complete our data set. However, our study demonstrates contamination of Swiss lakes with sulfonamide resistance genes and the potential of fresh water lakes preserve these genes, even remote from direct sources of pollution.

EPFL2013

Origines et flux de biocides et de filtres UV dans les stations d'épuration des eaux usées

Cécile Plagellat

Adverse effects on the environment have become a matter of increasing concern considering the increase of industrialization and of the amount of commercialized chemicals. At present, approximately 100'000 substances are on the market, 3000 are sold at high volumes. In Europe, 200 to 300 new substances are authorized every year (in Switzerland, approximately 50). Contamination is induced by consumption of numerous products frequently applied by private or professional users. Persistence and ecotoxicity of certain organic compounds contained in these products might have impacts on the quality of our environment. Knowledge on potential sources of these substances is the first step in order to limit their release. The project developed within the present PhD thesis aims at determining the sources of certain compounds by applying material flux analysis on the basis of sewage sludge. Presently, a large number of anthropogenic organic compounds originating from private households, craft industry, industry and stormwater is disposed of into the collector system and ends up in sewage sludge. Carbendazim, diuron, Irgarol 1051®, octhilinone, permethrin, tributyltin (TBT) and triphenyltin (TPT) comprise numerous applications as biocides and pesticides whilst methylbenzylidene camphor (4-MBC), octyl methoxy cinnamate (OMC), octocrylene (OC) and octyl triazone (OT) are used as UV-screens (type UVB) in a large number of cosmetic products. Their toxic effects on non-target organisms and their potential for bioaccumulation give rise to environmental concern. These substances are used as ingredients in products of daily use and are disposed of into wastewater. Due to their physico-chemical properties they are more or less lipophilic and are likely to persist in sewage sludge. On the basis of the analysis of sewage sludge samples from well characterized sites (catchments and wastewater treatment plants, WWTPs) it is possible to determine the sources (private households, craft industry, industry and stormwater). The first step of this study was the development of analytical methods which allow for quantification of these compounds in sewage sludge. Due to their different physico-chemical properties, four different methods were required. These methods have recovery rates ranging between 75 and 106 % and limits of detection in the order of μg/kg dry matter. The analysis of sludge from 12 sites obtained within 2 sampling periods show that most of the substances are present in all samples. Mean concentrations were 6,8 μg/kg dm (dry matter) for carbendazim, 9,5 μg/ kg d.m. for diuron, 98,1 μg/kg d.m. for permethrin, 148 μg/kg d.m. for TBT, 1777 μg/kg d.m.for 4-MBC, 110 μg/kg d.m. for OMC, 4834 μg/kg d.m. for OC and 5517 μg/kg d.m. for OT. Octhilinone was not detected whilst Irgarol 1051® and TPT were found in 7 and 11 samples, respectively. The transfer of these compounds from wastewater into sludge is an important parameter for material flux analysis on the basis of sewage sludge. A study on the fate of carbendazime and permethrin during wastewater treatment has been carried out on two WWTPs. Whilst removal of permethrin was high (>94%) up to 70% of carbendazime present in sewage were found in treatment plant effluents. Adsorption is an important process for removal of permethrin. However, only 4 to 15 % of the load in wastewater was transferred to sewage sludge. Carbendazim is mainly associated to the aqueous phase and thus, a very small quantity ends up in sludge (approximately 1%). Therefore, the loads found in sewage sludge are more or less representative for consumption of the compounds in the catchments according to their physico-chemical properties. Additionally, it has been shown that the part of permethrine ending up in sludge depends on the treatment techniques of the WWTPs. Thus, for comparison of the pollutant loads in sewage sludge between different sites their fate in the WWTPs has to be known. The loads per inhabitant of the three well characterized types of sites have been calculated in order to determine the sources of the substances. Type A comprises sites with a separate sewer system and a catchment where mainly private households are present. Type B has a combined sewer system collecting sewage from private households, craft industry and stormwater whilst type C comprises a combined sewer system which includes effluents from private households and industry as well as stormwater. The results are as follows: Stromwater is considered as main source of carbendazim in wastewater whilst diuron originates mainly from stormwater and from industrial effluents. Private households contribute significantly to the loads of permethrine and TBT in sewage. For UV-screens the loads from private households are also important but stormwater and industrial effluents are likely to be potential sources as well. A difference in consumption between rural (type A) and more urban sites (type B and C) is possible which might hamper a proper estimate of the sources of UV-screens.

EPFL2004

Characterisation of Hospital Wastewater: the Case of the CHUV

Laura Marie Blanc

The aim of this study was to characterize hospital effluents in investigating the CHUV importance as source of pollutants, the range and amounts of pharmaceuticals that are used in the hospital and the need of source treatment of the hospital sewage. The CHUV is the biggest hospital of Lausanne (Switzerland), and 71% of its beds are in a building named “BH” (Hospital Building). The BH treats around 609 patients a day and releases an important volume of water (735 litres per patient per day), potentially highly concentrated in pharmaceuticals. The drugs the most delivered to the BH patients are the analgesic Paracetamol (787 g/day) and two anti-inflammatory substances: Ibuprofen (106 g/day) and Mefenamic acid (78 g/day). Among the 39 analysed pharmaceuticals, the most concentrated in the BH effluents are Paracetamol (423 ng/l) and Ciprofloxacin (22 ng/l). The CHUV effluents plus many other wastes from Lausanne city (homes, other health centres, etc.) are treated in Vidy wastewater treatment plant (WWTP). The treated water is then released into Lake Geneva. The load of pharmaceuticals from the CHUV was found to be relatively small, compared to the total load entering in Vidy WWTP. Maximal percentages of the WWTP inputs from the BH effluents were shown by two antibiotics: Ciprofloxacin (2.8%) and Sulfamethoxazole (4.3%). This indicates that many drugs are excreted in domestic wastewater. Although the drug levels in the water from the hospital are low compared to the total levels reaching the WWTP, they still represent a significant point source and wastewater treatment at the hospital or in the WWTP is necessary. But Vidy WWTP was shown to be particularly inefficient in treating some of the pharmaceuticals that entered it. Therefore, the risk for the environment has been assessed. Diclofenac, Ibuprofen, Paracetamol, Propranolol, Ciprofloxacin, Clarithromycin, Sulfamethoxazole and 17α-Ethinylestradiol were from 2 to 601111 times more concentrated in Vidy WWTP effluents than acceptable in terms of calculated risk quotient (RQ) values. So, in some cases, a very important risk for the environment has been demonstrated here. Improvements of the WWTP efficiency are now in progress as a response to this. Treated water leaving Vidy WWTP is further diluted (at least 84.7 times) when it enters Lake Geneva, however this study revealed detectable levels of some pharmaceuticals in the lake itself, albeit below the predicted no effect concentration (PNEC) in all cases measured in this study.

2010