Advanced monitoring and modeling interface for an optimized design and operation of the MAR/SAT system of Agon-Coutainville (France)
AquaNES
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People in charge of the innovative practice :
Marie PETTENATI – m.pettenati@brgm.fr
AquaNES, a project launched in 2016 developed water and wastewater purification techniques, combining industrial and natural treatment processes. By demonstrating the impact and benefits of the different systems studied, the AquaNES project aimed to promote more sustainable water purification techniques to manage situations of water scarcity or excess and control the presence of micro-pollutants in the water cycle. Within the framework of the Horizon 2020 program, the project has brought together thirty scientific, industrial and academic partners involved in the water sector. Among its thirteen pilot sites, AquaNES launched the monitoring of subsoil water at the Agon-Coutainville (Manche) wastewater treatment site in March 2016, with the installation of observation piezometers to monitor the quality of natural filters. The site is operated by the company SAUR which manages the city’s wastewater. The system uses an activated sludge system (biological purification by micro-organisms) coupled with bio-filtration processes by reed bed and sand dune. This system makes it possible to protect the shellfish production area on the estuary by not discharging the wastewater directly into the sea. Also, the purified water allows for the artificial recharging of the coastal groundwater table with fresh water, and is used to irrigate the golf course on an occasional basis. The objective of the studies conducted at this demonstration site is to improve the quality and quantity of purified water by monitoring, managing, and modeling water and transfer processes in the soil and subsoil. The works included advanced chemical analysis and on-line salinity monitoring. The relevance of this combination of industrial and natural processes is studied in the framework of the AquaNES project through risk and life cycle analyses of the system. The valorization of the acquired data contributes to innovation in the water industry, and allows for efficient management of facilities within the water treatment and reuse sector.
Figure 1 : MAR/SAT system of Agon-Coutainville in France.
Responsible entity
The BRGM (French National Geological Survey) is the coordinator of a work package on aquifer management. It is the French public establishment of reference in the applications of Earth sciences to manage the resources and risks of the soil and subsoil. BRGM was created in 1959. It is a public establishment of an industrial and commercial nature (EPIC). Placed under the supervision of the Ministries of Research, Ecology and Economy, it is based in Orléans in France. BRGM’s work covers several activities: scientific research, expertise, innovation and transfer, analysis and experimentation, mine prevention and safety, higher education, continuing professional education, dissemination of knowledge and open science. It employs more than 1,000 people, including more than 700 engineers and researchers, in its 27 regional offices in metropolitan and overseas France. Its teams operate in some 30 countries. Six major scientific and societal issues structure BRGM’s scientific strategy: geology and knowledge of the subsoil, groundwater management, risks and land use planning, mineral resources and the circular economy, energy transition and the underground space, data, services and digital infrastructures.
Detailed explanation
The integrated system is based on the technical treatment by an activated sludge process in the wastewater treatment plant (WWTP), consisting of a pre-screening, a pumping station, a buffer tank, a rotary screen, oil and sand separators with sand classifiers (separator basins), two aeration basins (4,000 m3), a 470 m² clarifier, a metering channel for the treated water. The WWTP treats and infiltrates via the SAT system ~2,000 m3/day varying from 500 to 5000 m3/day depending on the season and vacations. In winter, the flow is significantly higher because the WWTP also receives rainwater. On the basis of an estimated capacity of 35,300 equivalent inhabitants, the Agon-Coutainville WWTP has a maximum DBO5 treatment capacity of 2,120 kg/day. The treated urban wastewater flows by gravity to one of the three infiltration basins located outside the WWTP. Once in the infiltration basins, the treated wastewater infiltrates through the reed beds to recharge the coastal aquifers composed of a 2 to 10 m layer of Quaternary sand. The three infiltration basins are flooded alternately throughout the year.
Figure 3 : Treatment process on the Agon-Coutainville site.
The objective of this demonstration site is to improve monitoring strategies and process modeling to evaluate the effectiveness of combining natural and engineered treatment systems in a coastal area and for reuse by:
Demonstrating the effectiveness of secondary wastewater treatment combined with reed bed filtration with MAR/SAT on groundwater quality and quantity;
Introducing new monitoring, data management, and subsurface modeling methods, including advanced chemical and isotopic analyses, to understand the ability of SAT to improve water quality;
Observe the fate of viruses/pathogens and other contaminants in treatment systems;
Evaluate the utility of the system in limiting saline intrusion in this sensitive coastal area using a hydrogeological/reactive transport model representing the state of the system;
Represent all of these interrelationships in a customized technology and communication tool.
Figure 4 : Conceptual diagram of the innovative practice.
Future outlook
The short-term outlooks are to develop tools oriented towards governance, notably the implementation of tertiary treatment solutions on a part of the watershed, and to weight the criteria by communicating with the ARS, the Water Agencies, and the communities. In the near future, recharge and reuse sites using non-conventional water will have to be the subject of a “site-specific” analysis in order to estimate the possibility of storage, reuse, and the associated environmental costs/benefits and co-benefits.
Institutional setting
The project partners are BRGM, Antea Group, ImaGeau, MicroLan, BioDetection Systems, Cranfield University, Berlin Water Competence Centre, with the help of the municipality of Agon-Coutainville, SAUR and the Coutainville golf course.
Geographical setting
The demonstration site is located in Agon-Coutainville. The commune of Agon-Coutainville is located in France in Normandy, along the western coast of the Manche, between the Pointe de la Hague and the Bay of Mont Saint Michel. The demonstration site is located near a shellfish farming area and consists of a full-scale operational wastewater treatment plant and a MAR/SAT system. The secondary treated wastewater is discharged into a natural reed bed from which it infiltrates the coastal aquifer. The extracted water is then used for golf course irrigation.
Figure 2 : Wastewater treatment plant of Agon-Coutainville.
Historical overview
2016: European funding under the Horizon Europe program, approval number 689450. One of the key factors that allowed the implementation of this practice is the site of Agon-Coutainville, which is a fragile environmental area since the 90’s and for which it was essential to avoid any discharge. At this site, there was a natural reed bed (2000 m²) in which it was decided to infiltrate wastewater treated by an activated sludge treatment. The obstacles to the implementation of this solution were mainly financial. Indeed, the financing levers were not well adapted for a reproduction of the approach at the time. On the other hand, the AquaNes project was developed on a pilot scale over a period of 3 years.
Evidence of benefits from implementation
There are advantages of using this innovative practice including a financial gain. The data collected confirm that the SAT system results in an additional reduction in salinity (P50 Cl: 550 mg/L for the WWTP outlet, 125 mg/L in the observation wells), in Escherichia Coli (E.Coli) concentrations up to 2.5 orders of magnitude and in regulated nutrient concentrations (e.g. NO3, Ptot) up to one order of magnitude. Micropollutants, primarily discharged from the WWTP, generally had higher (median) concentrations in the treated wastewater (WWTP outlet), exceeding the recommended environmental quality standards (EQS) for carbamazepine (CBZ) and diclofenac (DIC). The SAT system, in combination with natural recharge, significantly reduces concentrations of contaminants of concern such as benzotriazole, CBZ, and DIC concentrations, which overall fall below the recommended threshold values defined by the EQS. The decrease in concentrations is likely due to the combined effect of dilution of treated wastewater in the aquifer and biogeochemical reactions (sorption and/or degradation).
Figure 5 : Concentration of regulated nutrients in WWTP outlet effluent and groundwater for observation wells.
Replication potential in SUDOE region
The project has a reproducible character, mainly at a large scale (big cities). The human resources implemented require different levels of complementary expertise: researchers, research engineers, technicians, computer scientists, geochemists, hydrogeologists.
Key points of the innovative method
> Combination of natural processing and engineered systems > Monitoring and modeling interface > Controlled recharge of an aquifer
Acknowledgements
The innovative practice was suggested by Marie PETTENATI (BRGM) who also participated in the interview.
References
Unesco (2021). Managing aquifer recharge. A showcase for Resilience and Sustainability. Case study 16: soil aquifer treatment system to protect coastal ecosystem in Agon-Coutainville (Normandy, France). https://unesdoc.unesco.org/ark:/48223/pf0000379962
The scientific community recommends a substantial improvement in the knowledge of aquifers, the establishment of reliable monitoring networks and a greater involvement of the administration and users to achieve a sustainable management of aquifers. The main objective...
The Llobregat Delta Water Users' Community has designed recharge basins in Molins de Rei to recharge the Baix Llobregat aquifer. View of one of the reloading basins during the test phase The Llobregat Delta Water Users' Community is one of the nine partners in the...
Compilation of groundwater management success stories completed. Throughout April, the 30 cases of innovative practices in groundwater management have already been selected by the clusters participating in the project: PPA, CWP and AV. The task started with the...
Improvement of the knowledge and concerted management of the Aquifer System of the Northern Sahara through the use of satellite images
GEO-AQUIFER
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People in charge of the innovative practice :
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GEO-AQUIFER is the continuum of the SASS project and aimed to improve knowledge and concerted management of the Northern Sahara Aquifer System (SASS) through the use of satellite images. The project created an information and knowledge base to support sustainable transboundary management of the Northern Sahara aquifers at national and sub-regional levels. The project has thus improved the living conditions of the population through the development of knowledge and sustainable management of transboundary aquifers through the use of satellite data, in order to increase concerted action between Algeria, Libya and Tunisia.
Figure 1 : Location map of the North Sahara Aquifer System (SASS).
The project was executed by the Sahara and Sahel Observatory (OSS) with the support of the European Space Agency (ESA), and funded by the African Water Facility (AWF) for a duration of 18 months. The objectives of the project were to: (i) optimize the use of satellite data for the knowledge and management of the SASS aquifer shared by Algeria, Libya and Tunisia; (ii) provide the national agencies in charge of water management in the SASS countries with tools to strengthen and improve the consultation mechanism for an efficient and sustainable management of the shared water resource; (iii) to develop the capacities of the national agencies in the use of satellite data and the appropriation of these new technologies in order to obtain reliable data and information quickly and at a lower cost; and (iv) to ensure the replication to other African basins. The project has thus contributed to strengthen the capacities (use of satellite and geographic data) of the services in charge of water management in the countries concerned by the SASS aquifer system. It has also provided tools to these countries to better identify the uses, and pressures exerted by both population and climate change on the aquifer system. GEO-AQUIFER has thus implemented innovative technologies (satellite images), and has contributed to the strengthening of national capacities in a perspective of sustainability and reinforcement of the SASS concerted consultation mechanism.
Responsible entity
The Sahara and Sahel Observatory (OSS) is an international organization that operates in the arid, semi-arid, sub-humid and dry areas of the Sahara-Sahel region. Created in 1992, the OSS has been based in Tunis (Tunisia) since 2000. OSS has 26 African countries and 13 organizations among its members. OSS initiates and facilitates partnerships around common challenges related to shared water resources management, implementation of international agreements on desertification, biodiversity and climate change in the Sahara-Sahel region.
The main actions carried out by the OSS are
The implementation of multilateral agreements on desertification, biodiversity and climate change;
The promotion of regional and international initiatives related to environmental challenges in Africa;
The definition of concepts and harmonization of approaches and methodologies related to sustainable land and water resources management and climate change.
OSS necessarily relies on knowledge transfer, capacity building and awareness raising of all stakeholders. OSS activities and projects are financed respectively by voluntary contributions from member countries, and by grants and donations from development partners. With effective governance mechanisms and a competent, multicultural and multidisciplinary team, OSS makes a high value-added contribution to the international and African institutional landscape.
Institutional setting
The GEO-AQUIFER project is in line with the 2010 OSS strategy and the priorities of its “Water” program, which in its initial phase focuses on large transboundary aquifers in Africa. The project is consistent with the AWF’s areas of intervention, namely the management of transboundary water resources by supporting the joint development of shared waters and by supporting the improvement of knowledge in the fields of information systems and water resources management. GEO-AQUIFER is also part of the 2005-2009 operational program of the African Water Facility, by improving the framework of knowledge and concerted management of the SASS aquifer system shared by Algeria, Libya and Tunisia. The project is also perfectly in line with the NEPAD (New Partnership for Africa’s Development) priorities of integrated management of transboundary water resources and with the poverty reduction strategies of the SASS basin riparian countries, which have made water resources management a priority for sustainable development.
Geographical setting
The GEO-AQUIFER project covers the Northern Sahara Aquifer System (SASS) and the Tunisian-Libyan coastal aquifer of the Djeffara. The SASS covers more than one million km2 in Algeria, Tunisia and Libya. The extension and the thickness of the layers have favored the accumulation of considerable reserves, which are renewed little and are exploitable only in part. Over the last 40 years, the annual exploitation of the SASS has increased fivefold, reaching 3 times the average level of its natural recharge, and the aquifer is facing several major risks: strong transboundary interference, salinization of water, disappearance of artesianism, drying up of outlets, and excessive pumping heights. The Djeffara refers to the Tunisian-Libyan coastal plain, containing an aquifer system whose continental part extends over 40,000 km2. In terms of risk, the Djeffara is distinguished by a pronounced level of alert: in 40 years, withdrawals have also increased fivefold. This has resulted in significant drops in the water table in the coastal areas where exploitation is concentrated with very dangerous salt water intrusions.
Detailed explanation
The technical developments made during the project are:
The extension of the digital mapping of the land use of the AQUIFER project;
The creation of surface water maps on the SASS-Djeffara basin (Algeria, Tunisia, Libya);
The elaboration of detailed land cover maps and land cover change maps on about 15 sample areas;
The extension of the DTMs of the AQUIFER project and derived products on the SASS-Djeffara basin;
The creation of a hydro-geographic repository on the SASS-Djeffara basin, a regional virtual globe, and a data dissemination tool;
The development of capacities with the continuation of the trainings undertaken following the AQUIFER project, in particular in the techniques of production, management and exchange of geo-scientific data or research support.
Future outlook
In the near future, the OSS intends to replicate GEO-AQUIFER in other basins, thus fulfilling its vocation as a partnership platform and center of excellence for sustainable development in Africa. At the end of the project, a number of challenges remain:
better knowledge of the irrigated perimeters on the whole Libyan Djeffara;
better knowledge of the water withdrawals on the SASS and the Djeffara;
full access to the possibilities offered by the GEO-AQUIFER website;
better use of geo-scientific data and satellite images for the management of water resources and the ordinary functioning of the SASS Consultation Mechanism.
All these challenges, which are natural extensions of the project, should be part of future cooperation programs between the Sahara and Sahel Observatory and the African Water Facility.
Historical overview
The GEO-AQUIFER project reinforced and completed the AQUIFER pilot project initiated by the ESA which concerned 5 pilot areas of the SASS. It constitutes its extension to the whole basin.
Figure 2 : Location of the area of interest and the study sites.
The experimental project AQUIFER, stemming from the TIGER program, is an ESA initiative which aimed at valorizing satellite data, in particular those issued from ESA’s ERS and ENVISAT satellites, for applications related to the management and monitoring of water resources in Africa. Within the framework of the TIGER initiative and under the impetus of the OSS, ESA has chosen the SASS (Algeria, Tunisia, Libya) and Iullemeden (Mali, Niger, Nigeria) basins to concretize its commitment to support the implementation of the Johannesburg Action Plan. ESA is financing the AQUIFER project, to the definition of which OSS has closely contributed by participating in the drafting of the terms of reference of the call for tenders, by assisting the consultancy firm in charge of the implementation of the project and by ensuring the coordination of the final users for the implementation of the project.
The Sahara and Sahel Observatory (OSS) requested support from the African Water Facility (AWF) to improve the state of the art and management tools of the transboundary groundwater resources of the Northern Sahara Aquifer System (SASS).
The project started on June 6, 2007 in Tunis with a workshop gathering representatives of institutions in charge of water management in Algeria, Libya, and Tunisia. The project ended in 2009.
Evidence of benefits from implementation
The sustainability of the project’s achievements is ensured by the functioning of the SASS consultation mechanism set up by the three countries sharing the same resource. The SASS consultation mechanism, which constitutes a first experience at the world level of common groundwater management, has an operational structure financed by the countries for its functioning and the implementation of permanent activities (management of the networks, production of indicators). The GEO-AQUIFER project, which has certainly benefited from the establishment of the mechanism, has in return strongly contributed to the consolidation of the mechanism by putting into practice the concept of consultation. During the three years of the project, GEO-AQUIFER has indeed mobilized around the same objective the institutions of the water sector of Algeria, Tunisia and Libya, as well as engineering offices and consultants of the three countries around the same objectives. Through its contribution to the inventory of irrigated areas, and to the good knowledge of water withdrawals, it has contributed to ensure an objective, equitable, and sustainable operation of the consultation mechanism. For the national water agencies, it was important to properly locate the irrigation water withdrawal areas and thus facilitate the decisions within the framework of the SASS concertation mechanism with objective, transparent, neutral and comparable data.
Replication potential in SUDOE region
The project has a strong potential for replication thanks to the strong involvement of the OSS in the implementation of this project. All other African countries are beneficiaries of the methodologies implemented, which can be used for multiple applications related to water resources management. The project shows a strong replicability on other transboundary systems: at the condition of having an executing agency with the solidity of the OSS coupled with the pre-existence of an international consultation mechanism. The potential for replication at other scales, particularly trans-regional, is also significant. From a technical point of view, the project can be considered as an original and replicable model considering the following results: (i) the elaboration of digital maps of irrigated areas to serve as complementary and contradictory data, and to ensure a better reliability to the estimation of underground withdrawals, which are generally not very accurate; (ii) the elaboration of a common geographical reference frame for the three riparian countries of the transboundary system and the dissemination of the project’s products on the internet, and (iii) the training of hydrology practitioners in remote sensing techniques and hydro-geographical analysis methods.
The cost of the project was estimated to €564,300, and it benefited from grants from the African Development Bank and the OSS.
The key success factors were: (i) the stability of the project team, (ii) the involvement of national policymakers, (iii) the establishment of the concerted consultation mechanism, and (iv) the proactive role of the OSS. However, the project did not have the expected impact because it did not initiate a substantial communication program.
Key points of the innovative method
> Improved knowledge of transboundary systems through the use of satellite imagery > Information and knowledge base to support transboundary management
Acknowledgements
The innovative practice was suggested by Yvan KEDAJ (Aqua-Valley) and Abdel Kader DODO, Lamine BABA SY, and Nabil BEN KHATRA (OSS) participated in the interview.
The scientific community recommends a substantial improvement in the knowledge of aquifers, the establishment of reliable monitoring networks and a greater involvement of the administration and users to achieve a sustainable management of aquifers. The main objective...
The Llobregat Delta Water Users' Community has designed recharge basins in Molins de Rei to recharge the Baix Llobregat aquifer. View of one of the reloading basins during the test phase The Llobregat Delta Water Users' Community is one of the nine partners in the...
Compilation of groundwater management success stories completed. Throughout April, the 30 cases of innovative practices in groundwater management have already been selected by the clusters participating in the project: PPA, CWP and AV. The task started with the...
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