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Reference : UMR5245-FLOMOU-004
Workplace : CASTANET TOLOSAN
Date of publication : Friday, June 4, 2021
Scientific Responsible name : Pinelli Eric
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
The presence of organic micropollutants in wastewater is recognised as an emerging problem by the scientific and industrial communities. Although present at extremely low concentrations (ng/L range), many of them may be of (eco)toxicological concern, either as single compounds or as components of chemicals or cocktails. Among the many micropollutants included in the Water Framework Directive Monitoring List in 2015 and 2018, there are 3 macrolide antibiotics (erythromycin, azithromycin and clarithromycin), amoxicillin from the penicillin group and ciprofloxacin from the quinolone group), 3 hormones (estrone, estradiol and ethinyl estradiol) and an anti-inflammatory (diclofenac). The group of antibiotics is of particular concern from an (eco)toxicological point of view due to the increased development of antibiotic resistant microorganisms in wastewater treatment plants, including fluoroquinolines, carbapenems, clarithromycin, penicillin and others... Antibiotic-resistant infections are one of the greatest threats to human health, the environment and global food security.
Wastewater flows are a major contributor to the spread of these pollutants in the sewage system, collecting wastewater effluent from many users.
This type of wastewater treatment is usually based on compact technologies, such as membrane bioreactors (MBRs). In these systems, a high sludge retention time is applied, resulting in both high solids/biomass concentrations and a higher diversity of microbial communities. These operating conditions lead to high quality effluents in terms of suspended solids, protozoa and coliform bacteria and under optimal conditions, some viruses and phages. Similarly, the removal of moderately biodegradable organic micropollutants has been shown to be improved when operating at high sludge retention times and high biomass concentrations.
The topic aims to study the safety and efficiency of different innovative water treatments of decentralised systems - treatments based on membrane bioreactors - including some emerging contaminants such as organic micropollutants, antibiotic resistant microorganisms, pathogens and viruses.
Ultimately, the objective is to find an optimal treatment strategy to obtain a final effluent that is satisfactory from the point of view of its physicochemical and ecotoxic characterisation and/or suitable for reuse, in accordance with its bacteriological and chemical water quality.
The ecotoxicity of treated wastewater will be studied on aquatic ecosystems for the different treatment systems and by two types of approaches, (i) at the level of aquatic organisms (algae, diptera, daphnia, amphibians) under standardised exposure conditions with different levels of study (acute, chronic, genetic, microbiota, etc.), and on the other hand, at the level of aquatic organisms (algae, diptera, daphnia, amphibians, etc.). ), and on the other hand, at the level of an artificial ecosystem by using more realistic tools for assessing environmental effects such as aquatic microcosms that make it possible to reconstitute simplified ecosystems on a small scale integrating one or more biological links. In concrete terms, two types of approach will be favoured: (i) evaluation of the effects of the treatments using regulatory tests (OECD and ISO tests) to answer the fundamental question in terms of health and environmental risks, and (ii) deployment of a mechanistic approach to both the fate of micropollutants in the effluents and their toxicity, while taking place under environmentally relevant conditions using aquatic microcosms. In this perspective, biofilm-organism interactions as well as the intestinal microbiota of higher organisms will be analysed using molecular tools (flow cytometry, qPCR, high-throughput sequencing). Finally, antibiotic resistance genes will be quantified by high-throughput qPCR in the physical environment-organism continuum.
This research work is intended for a PhD student in the framework of the WP 7 of the PRESAGE project in the framework of the Aquatic Pollutants Joint Transnational Call 2020 - Water Challenges for a changing world of the Joint Programming Initiatives (JPIs) on Water, Oceans and Antimicrobial Resistance for the Functional Ecology and Environment Laboratory (UMR CNRS 5245) led by Régis CEREGHINO. The candidate will be attached to the Integrative ECotoxicology team led by Dr Arnaud Elger. Weekly laboratory hours: 38.5 hours. Leave will be taken during the contract period.
Constraints and risks
- Possibility of working shifts and hardship (weekends, holidays... activities related to life and animal welfare).
- Travel in Europe for experiments, presentation of results (deliverables) to European partner laboratories.
project PRESAGE in the framework of the Aquatic Pollutants Joint Transnational Call 2020 - Water Challenges for a changing world of the Joint Programming Initiatives (JPIs) on Water, Oceans and Antimicrobial Resistance
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