he Oxymore project involves the reuse of wastewater in coastal areas, as part of the first indirect drinking water production demonstrator in Europe, commissioned by Vendée Eau. Indirect drinking water treatment involves the replenishment of surface water reserves with finely-treated wastewaters, which are then used to supply drinking water production plants. Consequently, the production of high-quality, pathogen-free water containing low concentrations of trace organic contaminants (TrOCs) is necessary.

The project aims to evaluate two hybrid ozonation-nanofiltration (HONF) processes as more sustainable alternatives to the low-pressure reverse osmosis (LPRO) used on the demonstrator, in order to minimize energy and environmental footprints. HONF involves the simultaneous oxidative degradation and retention of organic matter and TrOCS. The added value of this coupling lies in its ability to reduce the drawbacks of each process, in particular a decrease of the membrane fouling and the rejection of the oxidation by-products formed during the ozonation stage.

The first HONF process, developed by the IEM Montpellier, uses ozone-enriched gas bubbles introduced into the NF cell containing a catalytic ceramic membrane. The second process, developed in Rennes, uses pre-ozonated water mixed with H2O2-doped wastewater, leaving the door open to the use of organic membranes. It is more specifically on this second process that the doctoral student recruited will be involved.

Work program

A detailed characterisation (ions, TrOCs, organic matter) of the effluent to be treated, taking into account seasonal variations, will be carried out. The organic matter in the effluent will be fractionated and carefully analysed by the IC2MP in Poitiers. Lyophilized fractions will then be used to construct a synthetic water model, with a chemical composition identical to that of the industrial effluent. This synthetic water model will be used at the beginning of the thesis for a laboratory study dedicated to the optimization of HONF process.

A scale-up will then be carried out on-site with monitoring for several months in parallel with the existing LPRO process. Detailed characterization of the organic matter and its evolution during the treatment will enable the rejection and oxidation mechanisms to be identified and understood. Mass spectrometry will be implemented to assess TrOCs removal efficiency and the formation of oxidation by-products. These chemical analyses will be combined with bioassays (carried out by INSERM Montpellier) to monitor the toxicity and ecotoxicity of the feed and of the permeates and retentates produced on-site. In addition to the validation of the performances of each configuration on a real wastewater, these long-term tests will allow to assess the ageing of the membranes and set up cleaning in place procedures.

These characterisations will be used as inputs for a technico-economic study (carried out as part of this thesis) and an environmental impact study (carried out by UniLasalle Rennes).

Partnership and financial support

This doctoral contract is funded by the French National Research Agency (OXYMORE collaborative research project – 670 kEuros). The Oxymore project brings together the expertise of 5 public and private academic teams:

The Rennes Institute of Chemical Sciences (ISCR, host laboratory for the doctoral student recruited);

The European Membrane Institute  (IEM) in Montpellier, which will host a post-doc in charge of developing a second hybrid ozonation/nanofiltration process;

The Poitiers Chemistry Institute: materials and natural ressources (IC2MP), in charge of the fractionation, concentration and characterisation of natural organic matter in water;

Institute of Cancer Research of Montpelier (IRCM, INSERM), in charge of bioassays;

UniLasalle Rennes, which will be in charge of the environmental impact study.

Within this consortium, Vendée Eau, the public company responsible for managing and distributing drinking water throughout the Vendée department, occupies a central position.Within this consortium, Vendée Eau, the public company responsible for managing and distributing drinking water throughout the Vendée department, occupies a central position.Within this consortium, Vendée Eau, the public company responsible for managing and distributing drinking water throughout the Vendée department, occupies a central position

Funding category: Autre financement public



PHD title: Doctorat mention chimie

PHD Country: France