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Treasure network

Françoise Breton, Technoscope - 28/02/2011

Coming together to improve water treatment

©IRD/Ruf, Thierry

Treasure is one of the networks developed as part of the EuroMediterranean 3+3 programme, created in 2006 to promote regional cooperation in the Mediterranean Basin. The aim of this multi-disciplinary, trans-Mediterranean network is to develop an effective water pollution control system that is capable of meeting growing water needs in North Africa. We spoke to two key participants about this exemplary collaboration.

What is the objective of the Treasure network?

Jérôme Harmand:  Originally, Treasure was a research project about fairly academic matters. The subject matter became more precise as we looked at the specific needs of the countries of North Africa and saw what could be socio-economically beneficial. The theme chosen – modelling and control of bio-processes for the re-use of wastewater in agriculture – touches upon two issues of crucial importance for Africa: the growing need for water, particularly for farming, and problems with the treatment of wastewater. Our project addresses both issues simultaneously, proposing a biological purification process that is able to provide water of sufficient quality for use in irrigation.

Brahim Cherki:  The Algerian government is investing a lot of money in purification stations but there is virtually no research concerning the development of membrane techniques, which at present are the only ones that provide water of sufficient quality for irrigation. We need to invest in this technology for the future. We have obtained funds from the Algerian Ministry of Research to co-finance the purchase of a bio-reactor, which will allow us to test the models we have designed to optimise these processes.

How does the network work?

Jérôme Harmand: The Treasure network is mainly based on exchanges and seminars. It is financed by Inria but since 2008 has also been funded by bilateral projects and other institutions from France (INRA - French National Institute for Agricultural Research, CIRAD - a French research centre working with developing countries to tackle international agricultural and development issues) or other partner countries. It also answers European calls for tender, such as the CoAdvise project. Today, Treasure has around ten partners, including Inria, INRA and the IRD (Institute of Research for Development) in France, as well as Spanish, Italian, Belgian, Tunisian and Algerian laboratories.

Brahim Cherki:  Treasure’s role is as an organiser, facilitating relations between partners with exceptional effectiveness by financing mobility. Our collaboration with Inria is a long-standing one, dating back to the first ‘control research school’ organised by ICPAM in Tlemcen in 2003. Since then we have held regular courses and symposia. But our involvement in the Euro-Mediterranean 3+3 programme, with the Treasure network on water treatment, has enabled us to finance a number of exchanges. We have taken part in schools in Narbonne, Sfax, Casablanca and Yamoussoukro, and established very promising contacts with Spanish, Italian and Tunisian teams. These exchanges allow us, in particular, to acquire knowledge in the field of biotechnologies, as we are a control laboratory, focusing on process control.

Has Treasure brought any other benefits to your laboratory in Tlemcen?

Brahim Cherki:  Thanks to our involvement in Treasure, we can also respond to calls for tender launched by other organisations. Our Air-Sud project, for example, was selected by the IRD, which enabled us to finance a significant part of the cost of our bio-reactor. But we have also been able to benefit from the European CoAdvise project, which has enabled us to finance PhD theses: two are being pursued at the Politecnico de Milano and two more in France, at INRA’s LBE with Jérôme Harmand and in the Modemic team in Montpellier.

What are the scientific stakes of Treasure, and what progress has been made?

Jérôme Harmand:  Anaerobic ecosystems – that is, those that develop in the absence of oxygen – offer numerous advantages over aerobic systems (which need oxygen to live). They use less energy, produce less sludge and emit methane, which can be used elsewhere. When paired with microporous membranes, these systems produce better-quality water than traditional treatment processes. However, in processes using membranes, predation among micro-organisms and cell death release very small molecules that may clog the membranes. These phenomena must be studied closely in order to optimise the system. Our role as mathematicians is to turn the biologists’ knowledge and data into equations, to look for and analyse the laws governing microbial ecosystems and, when these models have been validated by experimental data, to use them to optimise the process. This is familiar ground for Inria.

Brahim Cherki:  Hence the importance of the 50 litre bio-reactor, which will be up and running very shortly in Tlemcen. It will allow us to identify the biological parameters of the anaerobic bio-reactor model that we have developed and to test our hypotheses on how the membranes become clogged. We have written the dynamic equation governing the accumulation of microbial products in the microporous membrane. We now need to show that it is borne out by the experimental results. Whenever members of the network visit Tlemcen, we always invite an Algerian industrial company specialising in water treatment. This company has shown a keen interest in our work and would be interested in using the technologies we are developing.

Purification in a bio-reactor

 This process involves bringing wastewater into contact with micro-organisms which use the pollution to grow. The purified water is then separated from the sludge by decantation or using a physical barrier such as a filtration membrane. Ordinary systems are based on the activity of aerobic micro-organisms, i.e. those that need oxygen to live. They have two major disadvantages for the applications in question: they use a lot of energy, as they must be stirred constantly to aerate them, and they produce a large quantity of sludge, which we do not know what to do with. Furthermore, if the separation stage is performed by a gravity-based decantation system (without a physical barrier), the water is not suitable for irrigation as it may still contain pathogenic organisms.

 The anaerobic technique, meanwhile, is based on micro-organisms that can survive in the absence of oxygen. There is therefore no need to aerate the sludge but, in order for the technique to operate correctly, the temperature must be quite high (the optimal temperature being 37°), which makes it a treatment process that is particularly suited to arid climates. Another advantage of this technique is that it produces a much lower quantity of sludge and emits methane, which can be used elsewhere. When a membrane is used, the quality of the water obtained meets European standards for irrigation of farmland. So where’s the problem? The tiny molecules produced by the death of the micro-organisms remain in the circuit for a long time and are liable to clog up the filters quickly. Researchers have suggested a few possible solutions, such as blowing a constant stream of carbon dioxide through the membranes. These solutions must now be tested in real conditions on the lab bio-reactors in order to find the optimum operating conditions for the system.

Keywords: EuroMéditerranée 3+3 programme Irrigation North Africa Development Project team MODEMIC Treasure INRA IRD Projet CoAdvise Maghreb Jérôme Harmand Brahim Cherki

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