Forward

The European Green Deal is a monumental step in achieving a greener and more sustainable Europe, filled with promising targets which aim to culminate in no net emissions of greenhouse gases by 2050 and economic growth decoupled from resource use. It establishes great potential for a fairer economy, the revitalisation of rural areas and sustainability. Yet, the roadmap on how to actualise such targets has yet to be realised.

This policy brief provides a roadmap, by giving recommendations for 10 concrete steps that can be taken to achieve the European Green Deal through agroecology, especially the Biodiversity and Farm to Fork Strategies. It will focus on many of the technical aspects, as well as on research, social responsibilities and responsible governance. Each step is to be considered as a whole, rather than individually, as many steps require the other in order to create true transformation.

Agroecology is a holistic concept that embraces a diversity of interpretations, intentions and realities, depending on the country and its context, history, stakeholders and sociopolitical environment. Its aim is to restructure the food system in a way that maximises ecological processes to attain sustainability -encompassing agricultural practices, science and social movements (Wezel etal., 2009). While it is dynamic and ever-changing, it holds at its heart sustainable agricultural practices that include: the use of local resources, enhancing soil health and life (improving organic matter and biological activity), increased use of legumes for nitrogen fixing qualities, agroecological infrastructures (habitats for biodiversity conservation and beneficial species for pest control), recycling biomass (optimising and closing nutrient cycles), reducing dependence on external synthetic inputs, enhancing diversity in crops and livestock, and increasing resilience against climate change. These all strengthen synergy between the various elements of the system that transform our local, regional, national and trans-national food systems on a large scaleeconomically, politically and socially. Agroecology uses natural cycles and ecological processes instead of relying on chemicals to achieve sustainable food. Rather than purchasing expensive inputs, it aims for a lower input agriculture that uses local resources, increases soil life and maintains nutrient flows at the farm and territorial level (e.g. through legumes and manure for nitrogen fixing qualities). By creating diverse and long crop rotations, intercropping, using a diversity of crops and keeping constant soil cover, it creates a synergetic system that halts the pest and weed reproduction cycles and makes pesticides (insecticides, herbicides, fungicides) obsolete. It simultaneously minimises resource losses (water, nutrients, biomass). The focus in such a system is transformed from maximum yields to optimum yields, while also diminishing dependence on global trade.

Farm to Fork Target: Reduce fertiliser use by at least 20 % by 2030.

The reduction of pesticides is often automatically linked with the reduction of synthetic fertiliser use since plant varieties whose great yield is only possible with growth regulators and pesticides are no longer used. This can be achieved through the fertilisation that occurs through symbiotic fixation from leguminous crops and through nitrogen transfers from livestock, especially ruminants. These two systems should not be seen individually but in symbiosis as both are important tools to ensure human and environmental health (e.g. eutrophication, emissions), and keeps us within planetary boundaries.

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Farm to Fork Target: Reduce nutrient losses by at least 50 % while ensuring no deterioration on soil fertility One of the most important components of agroecological transformation is returning fertility to soils and valuing the innumerable services of soil organisms. Within agroecology, animals are vital to soil fertility, especially when livestock and crop production is reconnected in mixed crop-livestock systems. Such integrated systems either grow animals and crops on a single farm, or cooperate amongst neighbouring farms for the exchange of hay, straw and manure, creating regional autonomy. This is optimal for the reduction of fertilisers and nutrient losses, as animal manure can increase soil fertility on the spot or through nitrogen transfers, which additionally reduces animal waste, transport emissions related to feed and imported deforestation (which hurts global biodiversity and increases GHG emissions). The integration of crops and animals on a single farm, while sharing space at the same time or in rotation, creates deep interactions which provide environmental services and social benefits (e.g. economic resilience). Further, a regional system founded on a mosaic of diverse landscape structures creates an equilibrium for both crops and livestock needs. Within intensive conventional agriculture, animals are often kept indoors in conditions that not only increase diseases but cause severe animal welfare issues related to discomfort, pain, fear, distress, and abnormal behaviours. Extensively managed, grass-based livestock systems on the other hand, halt almost all of these concerns simply by animals living outside, giving them access to healthier feed provisioning and conditions. When a farmer includes rotational grazing and croplivestock rotations, intestinal parasites can be managed through the disruption of the host-pathogen cycles and herbal leys can be incorporated to regulate animal health without veterinary drugs. This change would also revitalise and maintain grasslands, increase biodiversity within grasslands, and should include diverse animal breeds that easily digest woody fodder, are more suited to local realities (i.e. climate, terrain), and are 'dual purpose' for both meat and milk. Such systems would prioritise breeds for their performance criteria from quantity of milk or meat, to their ability to adapt to a changing climate. Further, the mineral makeup of milk and meat from such systems also changes to create healthier diets with Omega-3 content of milk doubled when animals are feeding on grass which is critical for cardiovascular health in humans (IDDRI, 2018). Lastly, extensively managed systems give priority to crops directly consumed by humans as they are no longer in competition with feed, which is often imported from great distances with high GHG emissions, creating a more autonomous Europe.

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Biodiversity Strategy Target: Strictly protect at least a third of the EU's protected areas -representing 10% of the EU land and 10% of EU sea -including all remaining primary and old-growth forests as well as other carbon rich ecosystems, such as peatlands, grasslands, wetlands, mangroves and seagrass meadows.

The restoration of Europe's grasslands is not only important for their immense carbon sink qualities (can store up to 30% of the world's carbon) but they are also the heart of European biodiversity (up to 79 species in just 1 m2 in Europe) (IDDRI, 2018). Therefore, addressing biodiversity loss cannot be done without a focus on grasslands, which often include important agroecological infrastructure (hedges, wood clumps, grass strips, ponds, ditches) which provide food, shelter, and ecological and territorial connectivity. For biodiversity purposes it is important to focus on extensively managed permanent grassland to provide a continuity of landscape and habitats for reproduction, as tilled or fertilised grasslands lose species richness. Further, the conservation of diversified grasslands implies the support of the livestock systems which ensure their vitality, keeping traditional diets in a way that does not impact the planet. Increasing tree cover is important for many reasons, including to combat climate change, increase biodiversity and for animal welfare, but how and where those trees are planted is of utmost importance. If trees are planted in commercial monocultural forestry systems, the benefits derived from them, beyond carbon sequestration, are very limited. Similarly, large-scale tree planting in grassland areas where diversity is already very high would be counterproductive. Therefore, it is important that trees are planted to support and regenerate already functioning agroecosystems. The European Green Deal could use to accomplish such a target, as agroforestry is a multifunctional land use approach that delivers environmental, social and economic benefits that can be used at any scale, by all farmers, including small-scale farmers. The benefits of agroecological agroforestry systems are many: they control pests; improve soil fertility, water quality, and biodiversity; reduce erosion; sequester carbon; capture excess nitrogen; create buffers in storms and droughts; ensure ecological corridors and generate diversified incomes. Most importantly, agroforestry provides both economic and environmental resilience where disturbances and extreme weather events will continue to cause instability in coming years.

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Green Deal Target: The EU's goals are to reduce the environmental and climate footprint of the EU food system and strengthen its resilience, ensure food security in the face of climate change and biodiversity loss and lead a global transition towards competitive sustainability from farm to fork and tapping into new opportunities.

Increasing the diversity and number of crops grown on a single farm is necessary in order to create environmental and economic resilience to a changing climate which incorporates the use of annual, perennial and permanent crops. This includes variety in space and time, using a mix of practices that include intercropping, diversified rotations, agroforestry, and crop diversification at the farm scale. Such complexities can be used to provide economic (e.g. multiple incomes in case of pest outbreaks) and environmental tools (e.g. drought resistant varieties, resilience to climate change). It can also support healthy, diverse and culturally appropriate diets which respect food traditions. New crops, rarely used crop species, and locally adapted breeds and crops are important pillars for climate adaptation. It is important to mention that this does not mean the production of genetically modified seeds which seek to create a single variety of each crop that relies on synthetic inputs, instead of increasing system diversity. Further, the ability to save a seed, which is not possible with GMO crops, creates not only autonomy for the farmer, it is also a vital tool for climate mitigation as season after season, specific attributes are bred into the seed naturally, with the needs of that particular region. The heart of crop diversity is also the ability for communities to engage in food sovereignty and seed exchange, which preserves intergenerational land practices and cultural meaning. Increased diversity in plant and animal species ensures the sustainability and well functioning of that particular ecosystem, including the pollinators agriculture and human diets strongly rely on. Yet diversity is not only important within fauna and flora, but also within habitats. Within agroecology, mosaics of different landscapes in different forms and sizes, that serve both humans and non-human members of the environment, are fundamental. This includes forests, arable land, and grassland with agroecological infrastructure of hedges, woody clumps, grass strips, and ditches all within close proximity. These habitats and their functional biodiversity any insect or plant from becoming a pest, providing essential ecosystem services for agricultural production, as well as ecological corridors.

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Farm to Fork Target: Achieve 25 % of total farmland under organic farming by 2030.

Organic farming, in its most rigorous form, includes many agroecological practices for closed loop, ecologically sound systems that provide dignified incomes for farmers, as well as the preservation of family farming, which is responsible for over half of all food production in Europe (Eurostat, 2020). Organic farming calls for alternatives to pesticides, veterinary products, non-synthetic crop fertilisers, as well as higher animal welfare. Although organic farming is not (yet) focused on the more social aspects that are demanded in agroecological food systems, it has a focus on environmental degradation and human health that can help preserve natural resources, encourage biodiversity both inside the farm and in surrounding areas, sequester carbon, ensure soil health and eliminate many of the emissions and toxic repercussions of synthetic pesticides and fertilisers.

Increase regional research on best practices for all aspects of the food system including for climate, soil, land management, and crop and animal diversity Biodiversity Strategy Target: 10 billion euros under Horizon Europe [are] to be invested in R&I related to food, bioeconomy, natural resources, agriculture, fisheries, aquaculture and environment.

Research and innovation are key drivers in the agroecological transition to sustainable and healthy food systems. In order to ensure resilience under a changing climate, and to become less dependent on fossil fuel based global trade, it is important to invest in research that can provide farmers with state of the art data that is specific to their climates, terrains and realities. One of agroecology's fundamental pillars is focusing on the local and regional scale, creating strategies that are diverse

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in each farm and region, rather than a one-size-fits-all solution. Such research can go beyond the academic halls of Europe's universities and include the establishment of networks of living labs and EU partnerships that focus on agroecology, food and soil. An enabling framework to bring these ambitions to life will need to bridge many sectors such as finance, capacity, research, innovation and technology in order to provide systems-based research that moves away from quick fixes and silver-bullet solutions. Such research needs to be disseminated and paired with knowledge exchange and training that is farmer to farmer led. The AE4EU project has taken the first steps on many of these tasks, first by mapping agroecology across European countries to give an overview of the different realities of agroecology thus far, encompassing subjects such as living labs, science and research, education and training, social movements, as well as in practice. Through this initial mapping it was found that in order to improve the strength of the living lab concept, an important tool for agroecological transformation, it is important for each region to provide their own diffusion of the term and adjust it according to local realities. Next, the project will create a hub, a virtual space where individuals from all related professions can gather information and share knowledge, practices and experiences. The hub aims to be a space of connection for farmers, researchers, students, chefs, professors, citizens, social movements, NGO's and policy makers.

Promote participatory and multi-stakeholder approaches in knowledge generation

Green Deal Target: Reduce net emissions of greenhouse gases by at least 55% by 2030.

The EU has pledged to reduce greenhouse gas emissions and become climate neutral by 2050. This requires research and innovation by a variety of stakeholders in a participatory and co-creative process that is people-led, inclusive, transdisciplinary and holistic. AE4EU is engaging in such a process through the creation of a network of networks that aims to complement, support and link existing groups, initiatives and programmes that are working towards the development of agroecology. This network is led by 30 different organisations, mostly outside of the Horizon 2020 project, and will continue to exist once the project has ended. By enabling participation across all sectors, innovative solutions can be created that are rooted in equality and a just transition. This includes relinquishing power imbalances in the food system by treating uniformly all diverse ways of knowing, including traditional knowledge, lived experience, case studies and observations, to complement scientific data (Global Alliance for the Future of Food, 2021). In order to achieve climate neutrality, it is important to redesign our food system completely in a way that goes beyond production and focuses on socio-economic aspects such as responsible governance and re-establishing connections between growers and those who eat. Further, it is vital that short and long term considerations are included in all future decisionmaking for thoughtful transformation which addresses systemic issues and creates system-wide benefits.

Steps to Achieve the European Green Deal

Strongly decrease synthetic pesticides and fertilisers Increase mixed crop-livestock systems Enhance animal health and extensively manage livestock Restore and enlarge permanent grasslands Return trees to agricultural landscapes Diversify the types and number of crops grown on a single farm. Increase diversity of habitats Increase the adoption of organic farming Increase research on best practices at the local and regional scale for all aspects of the food system including for climate, soil, land management, and crop and animal diversity Promote participatory and multi-stakeholder approaches in knowledge generation 1. 2. 3. 4. 5. 6. 7. 8. 9.

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The way forward

The European Commission has done significant work to create strategies that will enable a just and sustainable transition for Europe through the Green Deal. Yet, the lack of frameworks to guide such a shift in agricultural production especially, has meant that the path has not yet gained critical momentum. AE4EU has created such a framework that although concrete, can be redefined to the local scale. This framework is characterised by a mosaic of different systems, landscapes and practices that are rooted in regionality and respect cultural traditions. Each member state can continue this work by creating their own policies tailored to their country's context and conditions which are guided by these 10 steps, while keeping in mind HLPE's 13 principles of agroecology, both in their state policies and through through their CAP Strategic Plans, especially through the eco-schemes, which AE4EU has written another policy brief with even more specific guidance.

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 3 Increase mixed crop-livestock systemsStrongly decrease synthetic pesticides and fertilisersFarm to Fork Target: Reduce by 50 % the use and risk of chemical pesticides by 2030.

3

  Restore and enlarge permanent grasslandsEnhance animal health and extensively manage livestock Target: Reduce sales of antimicrobials for farmed animals and in aquaculture by 50 % by 2030.

5

  Diversify the types and number of crops grown on a single farmReturn trees to agricultural landscapesBiodiversity Strategy Target: Plant 3 billion trees by 2030.

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  Increase the adoption of organic farmingIncrease diversity of habitatsBiodiversity Strategy Target: Bring back at least 10% of agricultural area under high diversity landscape features by 2030.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No101000478.


Stefano Canali

Corrado Ciaccia

Luca Colombo

Jessica Donham

Baptiste Grard

Ileana Iocola

Stefania Maurino

Alexander Wezel

Fostering the transformative role of agroecological research in Europe (Policy brief)

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

FOSTERING THE TRANSFORMATIVE ROLE OF AGROECOLOGICAL RESEARCH IN EUROPE

November 3, 2022

Policy Brief, AE4EU

Forward

Agroecology is a holistic concept that embraces a diversity of interpretations, intentions and realities, depending on the country and its context, history, stakeholders and sociopolitical environment. Its aim is to restructure the food system in a way that maximises ecological processes to attain sustainabilityencompassing agricultural practices, science and social movements (Gliessman 2007, Wezel et al. 2009).

Agroecology also represents a collective-action model to challenge and contrast the dominant agri-food system while creating sustainable alternatives built on place-based food interactions, food sovereignty, local knowledge and identity, and social justice [START_REF] Levidow | Agroecological research: conforming -or transforming the dominant agro-food regime?[END_REF][START_REF] Altieri | The agroecological revolution in Latin America: rescuing nature, ensuring food sovereignty, and empowering peasants[END_REF]. Nevertheless, agroecology is also adopted by actors who promote conventional and agro-industrial agriculture (Holt-Gimenez and Altieri 2013) through sustainable intensification approaches geared towards increasing productivity. These two visions (transformative vs conformative) create a very different role for agroecology, with varied outcomes and socio-technical dynamics, including how science is conceived and articulated.

Thus, amongst the broad range of topics identified in European agroecological research [START_REF] Wezel | Agroecology in Europe: Research, education, collective action networks, and alternative food systems[END_REF], some approaches are more in line with the dominant agri-food regime, while others can better integrate the participation of different actors and promote territorial development with a wider transformative role. Such analytical distinctions are necessary in order to set up appropriate agendas fostering the transformative role of agroecological research in Europe. This policy brief aims to provide research-based policy recommendations for policy makers that are responsible for the design and funding of research programmes related to sustainable agriculture, as well as agroecology. These are based on the results of the research carried out within the AE4EU project on European agroecological research projects and funding programmes.

Approach

The research was undertaken as a desk-based activity in order to collect information on research projects and funding programmes which deal with agroecology in Europe, principally at the European (within the Horizon framework which is funded by the European Union) and transnational (codesigned and co-funded by Member States with the participation of European Union) levels. Only projects where agroecology was explicitly mentioned or exemplified at least the third level (system redesign) of Gliessman's framework for classifying food system change, were considered [START_REF] Gliessman | Agroecology: The ecology of sustainable food systems, 3rd ed[END_REF]. Relevant key-informants (e.g., national funding agencies) for each European country also provided information on agroecological projects and programmes at the country level (designed and funded nationally).

Further, three different surveys were conducted and sent to: i) the coordinators of the identified research projects to learn more about their projects' features and their implementation of agroecological elements;

ii) the leaders of the identified funding research programmes to understand how agroecology is perceived by the programme designers, as well as how these programmes promote agri-food transformation through agroecology in Europe and the countries in question;

iii) any researcher involved in agroecology in order to gain a better understanding of the potential opportunities and obstacles for agroecological research.

All the data collected was integrated into a database. The information obtained through the surveys was further analysed to draw a comprehensive picture of the state of the art of the implementation of agroecological research in Europe, as well as to identify the needs for future cross collaboration between various countries and their networks.

Focal features of agroecological research in Europe

Agroecological research was found to predominantly focus on the transformation of the agri-food system, rather than on mere progress in efficiency. France, Germany, Italy, the Netherlands, Portugal, Spain, and the United Kingdom were found to be the most active countries engaged in agroecological research, as well as in transnational research collaborations. On the other hand, countries such as Malta, Moldova, and Ukraine were found to be less involved in this type of research.

The surveys showed that researchers, projects, and funding programmes all primarily focussed on improving efficiency (level 1 of Gliessman's framework), strengthening synergies (level 3), developing local economies (level 4), and the cocreation and sharing of knowledge (level 4) to support agri-food transformation through agroecology in Europe. Issues related to resilience (level 3), and the social and governance aspects (level 5) were the most uncommon. Further, the surveys confirmed that the actors most involved in agroecological research were researchers, farmers and their associations, cooperatives, and advisors. Only a few examples were found of limited participation by upstream and downstream value chain stakeholders, such as consumers.

Transdisciplinary approaches based on the interaction with non-academic actors in the cocreation of knowledge along the different phases of the research were primarily addressed by European projects, while transnational and national projects showed lower degrees of interaction, where actors were just informed or consulted. Living labs (LLs) are also becoming increasingly relevant. LLs are defined as "usercentred, open innovation ecosystems based on systematic user co-creation approach, integrating research and innovation processes in real life communities and settings." LLs, used as a means to strengthen co-innovation with non-academic actors and increase the impact of the research, were present in approximatively 50% of the European and the national projects, and only in about 20% of the transnational ones.

Most of the Research Infrastructures (RIs), which are "facilities, resources and services that are used by the research and innovation community to conduct research and foster innovation in their fields," that were used and developed in the research remained available after the end of the projects (89% of cases). Nevertheless, among these cases, only 41% of them consisted of data that was collected and elaborated within the project, and then shared and made available to the scientific community for future research.

An increased project duration was considered the most important change needed in funding and research programmes by both researchers and programmes leaders. In addition, researchers strongly urged the introduction of more flexibility and less bureaucracy in budget and partnership management in order to enable a dynamic and functional interaction with non-academic partners in projects implementation. Establish research programmes that consider the entire agri-food system and its actors, not only on the agronomic field and farming scales. Strengthen research cooperation and networks at the European scale by lowering the barriers that hinder the connection and participation of the currently less involved countries. Promote research programmes addressing, at least, level 3 (redesign) of Gliessman's framework, and especially those that go beyond this and include the social and governance aspects of level 4 and 5. On the other hand, diminish research programmes addressing only level 1 (efficiency) and 2 (substitution). Design research programmes that strengthen transdisciplinary research, and explicitly demand the implementation of transdisciplinary designs and processes. Enhance the involvement of a greater number of actors from the entire agri-food system, in particular those who have been less represented thus far, such as upstream and downstream value chain actors, and the non-economic actors of the food system (i.e., citizens). Identify important elements and traits of agroecological Living Labs to truly guarantee the implementation of transdisciplinary approaches. Promote appropriate policies regarding scientific data to guarantee data sharing and reuse within the scientific community (i.e., rewards, mandatory data sharing agreements). Introduce institutional and procedural innovation to guarantee higher flexibility in the implementation of research projects, especially within budget and partnership management Increase the duration of projects that are dealing with agroecology. Frame research programmes in a way that does not allow small projects whose results might be too simplified, as well as very large ones that cannot be efficiently managed.

Recommendations | 8

The way forward

The results and science-based recommendations provided in this policy brief aim to steer the actions of policy makers responsible for the design and funding of research programmes related to agroecology, in order to fortify its transformative role for the future of agriculture and sustainable food systems. Indeed, today more than anytime in the past, European and transnational research programmes and their funding schemes, can encourage a transformative paradigm due to new calls and partnerships which are now being launched and designed explicitly for agroecology within the new Horizon Europe framework. This larger, strengthened, and harmonized European perspective on agroecology can also support and drive the agroecological vision of the national funding programmes of various European countries.

Image 1 by Stefano Canali Images 2, 3, & 4 by Canva

Figure 1 :

 1 Figure 1: Methodological framework implemented. AE= Agroecology

Figure 2 :

 2 Figure 2: Actors in the Food System

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No101000478.


Alain Sié

Clément Hien

Nihal Trellu

Alain Stéphane Oturan

Bi Assémian

Henri Gouessé

Patrick Briton

Kopoin Drogui

Mehmet Adouby

Oturan

Sié Alain Hien

Clément Trellu
email: clement.trellu@univ-eiffel.fr

Nihal Oturan

Alain Stéphane Assémian

Bi Gouessé

Henri Briton

Patrick Drogui

Kopoin Adouby

Mehmet A Oturan
email: mehmet.oturan@univ-eiffel.fr

Comparison of homogeneous and heterogeneous electrochemical advanced oxidation processes for treatment of textile industry wastewater

Keywords: Anodic Oxidation, Electro-Fenton, Mineralization, Dye, Perchlorate

Introduction

Effluents from textile and tannery industry contain large amounts of dyes [START_REF] Assémian | In-situ generation of effective coagulant to treat textile bio-refractory wastewater: Optimization through response surface methodology[END_REF][START_REF] Benhafsa | Étude comparative de l'adsorption du colorant Victoria Bleu Basique à partir de solutions aqueuses sur du carton usagé et de la sciure de bois[END_REF][START_REF] Pajootan | Binary system dye removal by electrocoagulation from synthetic and real colored wastewaters[END_REF]. The discharge of such effluents in the environment presents several critical drawbacks, including the impact on the color of water bodies and critical effects related to the acute and long-term toxicity of some dyes [START_REF] Mansour | Les colorants textiles sources de contamination de l'eau : CRIBLAGE de la toxicité et des méthodes de traitement[END_REF]. The textile industry consumes more than 10 billion liters of water per day as well as 800 000 tons of dyes, of which 120 000 tons end up in wastewaters [START_REF] Mansour | Les colorants textiles sources de contamination de l'eau : CRIBLAGE de la toxicité et des méthodes de traitement[END_REF].

These very specific effluents contain high concentrations of dyes as well as other organic and mineral compounds depending on the dyeing process. Biological treatments are usually not suitable because of the low biodegradability of dyes, low N content, high salinity and high pH of these effluents [START_REF] Aravind | An integrated (electro-and biooxidation) approach for remediation of industrial wastewater containing azo-dyes: Understanding the degradation mechanism and toxicity assessment[END_REF]. Strong adverse effects were also observed from the discharge of these effluents in municipal wastewater due to their toxic effects on the biomass of conventional activated sludge process [START_REF] Gebrati | Inhibiting effect of textile wastewater on the activity of sludge from the biological treatment process of the activated sludge plant[END_REF]. Therefore, advanced processes have to be developed for on-site treatment of these hazardous effluents [START_REF] Aravind | An integrated (electro-and biooxidation) approach for remediation of industrial wastewater containing azo-dyes: Understanding the degradation mechanism and toxicity assessment[END_REF][START_REF] Brillas | Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review[END_REF].

Coagulation and electro-coagulation have been widely studied for the treatment of textile wastewater [START_REF] Brillas | Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review[END_REF][START_REF] Khandegar | Electrocoagulation for the treatment of textile industry effluent -A review[END_REF]. For example, electro-coagulation was able to remove 99% of turbidity but only 79% of chemical oxygen demand (COD) from a textile industry effluent (not enough for meeting environmental standards) [START_REF] Assémian | In-situ generation of effective coagulant to treat textile bio-refractory wastewater: Optimization through response surface methodology[END_REF]. Moreover, such treatment involves only a transfer of pollutants from the liquid to the solid phase and the generated sludge represents an additional waste to manage. Conventional oxidation processes using ozone or Fenton process have also been applied. While the removal of the color is very fast, an important issue is usually related to the recalcitrance of some degradation by-products [START_REF] Mandal | Treatment of leather industry wastewater by aerobic biological and Fenton oxidation process[END_REF][START_REF] Constapel | Degradation of reactive dyes in wastewater from the textile industry by ozone: Analysis of the products by accurate masses[END_REF][START_REF] Ciardelli | The treatment and reuse of wastewater in the textile industry by means of ozonation and electroflocculation[END_REF][START_REF] Barros | Decolorizing dye wastewater from the agate industry with Fenton oxidation process[END_REF]. A pH adjustment step is also often required for optimization of these processes [START_REF] Ölmez | The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation[END_REF][START_REF] Bautista | An overview of the application of Fenton oxidation to industrial wastewaters treatment[END_REF].

Electrochemical advanced oxidation processes (EAOPs) are emerging processes presenting a crucial advantage related to their non-selectivity for the full mineralization of organic pollutants [START_REF] Martínez-Huitle | Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review[END_REF][START_REF] Sirés | Electrochemical advanced oxidation processes: today and tomorrow[END_REF][START_REF] Oturan | Electrochemical advanced oxidation technologies for removal of organic pollutants from water[END_REF][START_REF] Oturan | Outstanding performances of the BDD film anode in electro-Fenton process: Applications and comparative performance[END_REF][START_REF] Anglada | Laboratory and pilot plant scale study on the electrochemical oxidation of landfill leachate[END_REF][START_REF] Chaplin | Critical review of electrochemical advanced oxidation processes for water treatment applications[END_REF][START_REF] Ganzenko | Electro-Fenton treatment of a complex pharmaceutical mixture: Mineralization efficiency and biodegradability enhancement[END_REF][START_REF] Trellu | Comparative study on the removal of humic acids from drinking water by anodic oxidation and electro-Fenton processes: Mineralization efficiency and modelling[END_REF]. They are based on the generation of hydroxyl radicals (  OH), the second most powerful oxidant known [START_REF] Latimer | Oxidation Potentials[END_REF]. Electro-Fenton (EF) and anodic oxidation (AO) are the two most popular EAOPs [START_REF] Martínez-Huitle | Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review[END_REF]. The AO process is based on the generation of  OH from water oxidation (Eq. 1) at the surface of anode material with high overpotential for oxygen evolution reaction [START_REF] Panizza | Direct and mediated anodic oxidation of organic pollutants[END_REF][START_REF] Kapałka | The importance of electrode material in environmental electrochemistry: Formation and reactivity of free hydroxyl radicals on borondoped diamond electrodes[END_REF]. Other oxidant species can also be generated depending on electrode materials and ions in the solution. For example, active chlorine and persulfates can be generated in effluents containing Cl -and SO4 2-ions [START_REF] Martínez-Huitle | Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review[END_REF]. The EF process is based on the formation of  OH from electrochemical generation of the Fenton's reagent (Fe 2+ and H2O2) (Eq. 2) by (i) the two electron reduction of dissolved O2 on carbonaceous cathode materials and (ii) the one electron reduction of Fe 3+ to Fe 2+ at the cathode [START_REF] Brillas | Electro-Fenton process and related electrochemical technologies based on Fenton's reaction chemistry[END_REF][START_REF]Electro-Fenton Process: New Trends and Scale-Up[END_REF]. By using a suitable anode material, formation of  OH at the surface of the anode can also enhance the oxidation power of the EF process [START_REF] Oturan | Outstanding performances of the BDD film anode in electro-Fenton process: Applications and comparative performance[END_REF][START_REF] Oturan | Comparative Performance of Ten Electrodes in Electro-Fenton Process for Removal of Organic Pollutants from Water[END_REF].

M + H2O  M( • OH) + H + + e - (1)
Fe 2+ + H2O2  Fe 3+ + • OH + OH -

Several studies have reported the possibility to use EAOPs for the degradation and mineralization of a large range of organic compounds, including dyes [START_REF] Brillas | Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review[END_REF][START_REF] Raghu | Evaluation of electrochemical oxidation techniques for degradation of dye effluents-A comparative approach[END_REF][START_REF] Espinoza | Mineralization of the textile dye acid yellow 42 by solar photoelectro-Fenton in a lab-pilot plant[END_REF][START_REF] Titchou | Comparative study of the removal of direct red 23 by anodic oxidation, electro-Fenton, photo-anodic oxidation and photoelectro-Fenton in chloride and sulfate media[END_REF][START_REF] Nidheesh | An overview on the removal of synthetic dyes from water by electrochemical advanced oxidation processes[END_REF]. However, there is a lack in treatment of real wastewaters by EAOPs [START_REF] Karim | Boron-doped diamond electrodes for the mineralization of organic pollutants in the real wastewater[END_REF]. Therefore, further development of EAOPs still requires addressing several challenges such as (i) the optimization of the process for a specific application, (ii) the understanding of reaction mechanisms in complex real effluents and (iii) the evaluation of the formation of toxic byproducts generated during the process [START_REF] Martínez-Huitle | Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review[END_REF][START_REF] Chaplin | Critical review of electrochemical advanced oxidation processes for water treatment applications[END_REF][START_REF] Radjenovic | Challenges and Opportunities for Electrochemical Processes as Next-Generation Technologies for the Treatment of Contaminated Water[END_REF]. Particularly, it is important to well understand the different advantages and drawbacks of the different EAOPs. The • OH are generated in a different way during AO and EF. They are homogeneously generated in the bulk solution in the EF process, while they are generated and accumulated at the surface of the anode in the AO process [START_REF] Sirés | Electrochemical advanced oxidation processes: today and tomorrow[END_REF][START_REF] Oturan | Outstanding performances of the BDD film anode in electro-Fenton process: Applications and comparative performance[END_REF][START_REF] Trellu | Comparative study on the removal of humic acids from drinking water by anodic oxidation and electro-Fenton processes: Mineralization efficiency and modelling[END_REF][START_REF] Kapałka | The importance of electrode material in environmental electrochemistry: Formation and reactivity of free hydroxyl radicals on borondoped diamond electrodes[END_REF][START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF]. Therefore, the aim of this study was to compare AO and EF processes for the treatment of a real effluent from the textile industry.

The different behaviors in terms of degradation and mineralization kinetics of organic compounds were emphasized. Moreover, the evolution of chlorate (ClO3 -) and perchlorate (ClO4 -) generated from oxidation of chloride was monitored since it is an important issue that should be further taken into consideration for integration of EAOPs in a real wastewater treatment system.

Material and methods

Chemicals

All chemicals were HPLC or analytical grade. Sulfuric acid (98%) and nitric acid (65%) were provided from Fluka. Chemical reagents for determination of chemical oxygen demand (COD) were obtained from Sigma Aldrich (K2CrO7 and Ag2SO4) or Merck (Hg2SO4). Iron (II) sulfate heptahydrate (FeSO4 • 7H2O, 99.9%) and potassium hydrogen phthalate (C8H5KO4, 99.95%) were obtained from Merck. Dilutions and solutions were prepared with ultra-pure water produced by a Milli-Q system (resistivity > 18.2 MΩ cm at 25 °C). The dye wastewater was obtained from a textile industry in Ivory Coast. Various dyes were provided by the textile industry in order to identify the main dye contained in the effluent.

Electrochemical reactor

An undivided cylindrical open batch reactor was used for performing electrochemical processes. The total volume of the treated solution was 230 mL and it was maintained under continuous magnetic agitation. Experiments were performed under galvanostatic conditions using a DC power supply (Hameg, HM8040-3).

For the AO process, plate electrodes were placed face to face with an inter-electrode distance of 2 cm. The anode was a boron-doped diamond (BDD) thin film deposited onto a niobium (Nb) substrate from Condias (6 × 4 cm 2 ), while the cathode was stainless steel AISI 304 obtained from Goodfellow (6 × 4 cm 2 ). The influence of the solution pH (3, 8 and 13.4) of the effluent was studied by adjustment of the initial pH with sulfuric acid.

For the EF process, a carbon felt obtained from Mersen (16 × 5 cm 2 ) was used as cathode and placed on the inner wall of the cylindrical reactor. The anode was placed at the center of the reactor, using either a Pt (noted EF/Pt process) or a BDD anode (noted EF/BDD process). A concentration of 0.1 mM of iron (II) was added to the solution as catalyst (since iron was not present in the raw effluent) and air was continuously bubbled in the solution in order to provide sufficient dissolved oxygen for production of hydrogen peroxide at the cathode. This reactor setup was similar to the one reported in previous studies [START_REF] Ganzenko | Electro-Fenton treatment of a complex pharmaceutical mixture: Mineralization efficiency and biodegradability enhancement[END_REF][START_REF] Trellu | Comparative study on the removal of humic acids from drinking water by anodic oxidation and electro-Fenton processes: Mineralization efficiency and modelling[END_REF][START_REF] Oturan | Comparative Performance of Ten Electrodes in Electro-Fenton Process for Removal of Organic Pollutants from Water[END_REF][START_REF] Trellu | Regeneration of Activated Carbon Fiber by the Electro-Fenton Process[END_REF]. All EF experiments were performed at initial pH of 3 (adjusted with sulfuric acid) in order to avoid precipitation of iron.

The conductivity of the effluent was sufficient to perform the EAOPs without addition of any additional salt.

Experiments were repeated twice and mean values were used to build the graphs.

Total organic carbon (TOC) analysis

TOC analyses were performed in order to monitor the mineralization rate of the organic matter of the treated solution. Analyses were carried out using a TOC-L from Shimadzu with the non-purgeable organic carbon method. Calibration was performed using potassium hydrogen phthalate in the range 0.20 -20 mg L -1 . Analyses were repeated 2 times, or 3 times if the coefficient of variation was above 2.0%.

Chemical oxygen demand (COD) analysis

Samples were mixed with the digestion solution (containing K2CrO7, H2SO4, Ag2SO4 and Hg2SO4) and incubated at 148 °C for 2 h in a Spectroquant® TR 420 digester (Merck).

Analysis was then performed using a Spectroquant® Nova 60 photometer (Merck).

Current efficiency and energy consumption

Current efficiency (CECOD) for COD removal was calculated using the Eq. 3.

CECOD (%) = ( ) * 100 ( 3
)
where COD0 is the initial COD (mg L -1 ), t is the treatment time (s), CODt is the COD at time of treatment t, I is the current intensity (A), V is the volume of the solution (L) and F is the Faraday constant.

Current efficiency for Cl -oxidation to ClO3 -and ClO4 -(CEClOx) was calculated using the Eq.

4.

CEClOx (%) =

[ ] + [ ] * 100 (4)
where [ClO3 -] and [ClO4 -] are the amount of chlorate and perchlorate generated (in M) and 6 and 8 represents the number of electrons involved in the oxidation of Cl -to ClO3 -and ClO4 -, respectively.

Electrical energy consumption (EC) per kg of TOC removed was calculated according to the Eq. 5.

EC (kWh (kg TOC)

-1 ) = ( ) ( 5
)
where U is the cell potential (V) and TOC is the total organic carbon (mg L -1 ) at time 0 and t (h), respectively.

EC per m 3 of treated water was calculated according to the Eq. 6.

EC (kWh m -3 ) = (6)

UV-vis absorbance analysis

UV-vis absorbance analyses were performed in order to follow the discoloration of the effluent, which indicates the degradation of the dyes. Analyses were performed 668 nm (i.e. maximum of absorbance of the effluent in the visible region). Full UV-vis spectra were also recorded in order to better understand the evolution of the nature of organic compounds during the treatment.

Ion chromatography

Ion chromatography was used for analysis of the main anions in the effluent (Cl -and SO4 2-) as well as for monitoring the formation of ClO3 -and ClO4 -during the treatment. Analyses were performed with a Dionex ICS-1000 equipped with a conductivity detector DS6, an ASRS 300 suppressor, an anionic column AS4A-SC (4 mm × 250 mm) and an injection loop of 25 L.

The mobile phase was 1.8 mM sodium carbonate (Na2CO3) and 1.7 mM of sodium bicarbonate (NaHCO3). Elution was carried out in isocratic mode with a flow rate of 2 mL min -1 .

Results and discussion

Characterization of the effluent

The effluent treated in this study was directly sampled from wastewaters of the textile industry TEX-CI Gronfreville located at Bouaké (Ivory Coast). Physicochemical characteristics of the effluent are reported in Table 1 and they are compared to national regulations and recommendations from the World Health Organization. High organic loading and a very alkaline pH make this effluent very difficult to treat by most of the conventional techniques without a pH adjustment.

Another important characteristic of this effluent was the high concentrations of sodium, chloride and sulfate ions. They come from the addition of sodium hydroxide (NaOH), sodium chloride (NaCl), sodium hydrosulfite (Na S O ) and sodium hypochlorite (NaClO) during the various steps of the textile industry (bleaching, mercerization, desizing, dyeing). The presence of these salts resulted in a high conductivity, which was suitable for application of the electrochemical process without further addition of any additional salt.

The UV-vis absorbance spectrum of the effluent is presented in Fig. 1. Two significant absorbance peaks were observed in the visible region, at 624 and 668 nm. These peaks are ascribed to the chromophore groups of a dye. The effluent spectrum was then compared with the spectrum of various individual dyes used by the textile industry (Fig. 1 (chromophore) groups [START_REF] Belbachir | Adsorption of Bezathren dyes onto sodic bentonite from aqueous solutions[END_REF]. Besides, for a similar value of absorption in the visible region, the absorbance of the effluent in the UV region was much higher than for BDB dye. It was ascribed to the presence of organic additives absorbing in the UV region such as detergents, surfactants, binders or thickener used by the textile industry. These results highlight that this kind of effluent is a complex mixture of organic and inorganic compounds that is difficult to treat using conventional treatment methods.

Comparison of EF (homogeneous) and AO (heterogeneous) processes for mineralization of organic compounds in textile wastewater

The first objective of this study was to compare the effectiveness of the different EAOPs (AO with BDD anode (AO/BDD), EF with Pt anode (EF/Pt) and EF with BDD anode (EF/BDD))

for the removal of TOC. The evolution of TOC in the solution was monitored in order to follow the mineralization kinetic of organics in the solution (Fig. 2a). After 6 h of treatment at 200 mA (current density of 8.3 mA cm -2 ), 52%, 75% and 95% of the initial TOC was removed from the solution by using EF/Pt, AO/BDD and EF/BDD, respectively. The higher efficiency of EF/BDD was explained by formation of a larger amount of  OH coming from both water oxidation at the BDD surface and Fenton's reaction in the bulk. However, it is interesting to notice that  OH are not generated in the same way during EF (homogeneously in Raw effluent BDB the bulk) and AO (heterogeneously at the anode surface) processes. The next objective was therefore to understand the impact on the mineralization kinetics.

Linear regression analysis of mineralization kinetics highlighted different behaviors.

Mineralization of organic compounds by AO/BDD process clearly followed a pseudo-zero order kinetic (Eq. 8 and Fig. 2b) (k0 = 50 mg L -1 h -1 ). In this case,  OH are generated and accumulated in a heterogeneous way, only at the surface of the BDD anode [START_REF] Kapałka | The importance of electrode material in environmental electrochemistry: Formation and reactivity of free hydroxyl radicals on borondoped diamond electrodes[END_REF]. Therefore, this kinetic behavior was explained by the high concentration of organic compounds compared to the current intensity supplied to the system [START_REF] Panizza | Direct and mediated anodic oxidation of organic pollutants[END_REF][START_REF] Rodrigo | Oxidation of 4-chlorophenol at boron-doped diamond electrode for wastewater treatment[END_REF]. Considering a typical mass transfer coefficient of organic compounds from the bulk to the electrode surface in such batch configuration (km = 3.10 -5 m s -1 ), the limiting current density (Eq. 7) was calculated as 40 mA cm -2 at the beginning of the process [START_REF] Panizza | Direct and mediated anodic oxidation of organic pollutants[END_REF]. It is also possible to calculate that the process was operated under current limitation as long as the removal rate of COD was below ≈ 80% (i.e.

almost during the whole 6 h of treatment). During this period, the reaction rate depends only on current and not on the concentration of organic compounds, thus explaining why a pseudozero order kinetic was obtained.

𝑗 = 4 𝐹 𝑘 𝐶𝑂𝐷 (7)
with 𝑗 , the limiting current density (A m -2 ); 𝐹, the Faraday constant; 𝑘 , the mass transport coefficient (m s -1 ) and COD, the chemical oxygen demand (mol m -3 )

( ) = 𝑘 (8)
with 𝑘 , the pseudo-zero order rate constant By comparison, EF/Pt and EF/BDD processes followed rather a pseudo-first order kinetic (Eq. 9) for the mineralization of organic compounds (Fig. 2c). The mineralization rate depends, in this case, on the concentration of organic matter in the solution. The EF/Pt process generates  OH in a homogeneous way in the bulk. These  OH have very short lifetime, e.g., the reaction rate between two  OH (k = 5.5 × 10 9 mol s -1 L -1 ) [START_REF] Buxton | Critical-Review of Rate Constants for Reactions of Hydrated Electrons, Hydrogen-Atoms and Hydroxyl Radicals (.oh/.o-) in Aqueous-Solution[END_REF] is in the same order of magnitude than the reaction rate between  OH aromatic compounds (k = 10 8 -10 10 mol s -1 L -1 ) [START_REF] Buxton | Critical-Review of Rate Constants for Reactions of Hydrated Electrons, Hydrogen-Atoms and Hydroxyl Radicals (.oh/.o-) in Aqueous-Solution[END_REF]. Therefore, the promotion of the reaction of  OH with organic compounds (instead of waste reactions) is strongly dependent on the concentration of organic matter in the solution.

( ) = 𝑘 * 𝑇𝑂𝐶(𝑡) (9)
with 𝑘 , the pseudo-first order rate constant

The use of a BDD electrode, as anode in the EF process, strongly increased the mineralization kinetics (k1 = 0.12 and 0.38 h -1 for EF/Pt and EF/BDD, respectively) due to the higher contribution of heterogeneous  OH, generated on the surface of BDD anode, for mineralization of organic compounds, compared to Pt anode. Pt is an active anode and therefore it is not able of accumulating large amounts of  OH on its surface. The degradation of organic compounds take place can only from direct electron transfer, which is a selective mechanism contributing in a minor way to the mineralization. These results obtained in a real complex effluent confirm that a detailed mineralization kinetic model of EF-based processes should take into consideration both homogeneous reactions in the bulk and heterogeneous reaction at the anode, as proposed by Mousset et al. (2019) [START_REF] Mousset | Charge transfer/mass transport competition in advanced hybrid electrocatalytic wastewater treatment: Development of a new current efficiency relation[END_REF].

Comparison of homogeneous (EF) and heterogeneous (AO) processes for degradation of dyes and evolution of by-products

The evolution of the UV-vis spectrum of the effluent during treatment by the different processes was then followed (Fig. 3). TOC is a parameter only assessing the mineralization yield of organic matter. However, the mineralization is a complex process generating several intermediates products during the degradation of organic compounds. Therefore, the formation of intermediates and end by-products is also an important phenomenon to be considered. The evolution of the shape of the UV-vis spectrum provided indications on the evolution of the nature of organic compounds in this complex effluent. As expected, the absorbance of the solution decreased during both processes because of the degradation of dyes. However, different behaviors were observed between EF and AO processes.

A very fast decrease of the absorbance was observed in the visible region (discoloration of the effluent) during the EF process (Fig. 3a). The color decreased rapidly owing to the fast reaction of  OH generated homogeneously in the bulk with the aromatic structure of BDB previously identified as the main dye in the effluent. The absolute reaction rate constant of  OH with dyes is usually in the range 10 9 -10 10 M -1 s -1 [START_REF] Ozcan | Removal of Acid Orange 7 from water by electrochemically generated Fenton's reagent[END_REF][START_REF] Lahkimi | Removal of textile dyes from water by the electro-Fenton process[END_REF] s -1 for oxalic acid) [START_REF] Knud | Pulse radiolysis of oxalic acid and oxalates[END_REF][START_REF] Oturan | Reaction sequence for the mineralization of the short-chain carboxylic acids usually formed upon cleavage of aromatics during electrochemical Fenton treatment[END_REF].

A much slower discoloration of the effluent was observed during AO/BDD because of the mass transport limitation of dye from the bulk to the electrode surface (Fig. 3c). The discoloration kinetics (based on absorbance measured at λmax = 668 nm) followed a pseudofirst order kinetic with k1 = 0.61 h -1 for AO and k1 = 7.3 h -1 for EF/BDD processes. The decrease of 75% of the absorbance at 668 nm required 2 h of treatment by AO/BDD compared to only 0.17 h with EF/BDD. This is ascribed to much more favorable mass transport conditions for reactions of dyes with  OH homogeneously formed in the bulk, compared to reaction with  OH heterogeneously generated at the anode surface.

Besides, on the contrary to EF, the shape of the UV-vis spectrum of the effluent remained similar during the whole treatment using AO/BDD process (Fig. 3b). For instance, the decrease of the absorbance at 254 nm using AO/BDD process was close to the decrease obtained at 668 nm (Fig. SI-3 and SI-4). These results indicate that the dye was rapidly mineralized after its initial degradation step, without accumulation of aromatic by-products.

This phenomenon is tightly related to the specific way to generate  OH during AO with BDD anode. In fact, a large amount of  OH is accumulated on the anode surface and direct electron transfer can also occur for degradation of some by-products such as short-chain carboxylic acids. Therefore, organic compounds can be rapidly mineralized once reached the anode surface and only a low amount of by-products are able to diffuse from the anode surface to the bulk solution. Mediated oxidation in the bulk, based on active chlorine or sulfate radical species, could also have participated in oxidation mechanisms during AO/BDD [START_REF] Martínez-Huitle | Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review[END_REF][START_REF] Panizza | Direct and mediated anodic oxidation of organic pollutants[END_REF][START_REF] Farhat | Oxidative capacitance of sulfate-based boron-doped diamond electrochemical system[END_REF].

However, the obtained results indicated that homogeneous oxidation of dyes in the bulk was not very significant during AO/BDD. A complete combustion of organic compounds in the vicinity of the anode surface seems to be the most consistent oxidation mechanism in this case. It might be ascribed to (i) lower reaction rate of organic compounds with these oxidant species and (ii) fast reaction of these oxidant species in the vicinity of the electrode surface since the AO/BDD process was operated under current limitation.

Overall, both processes present advantages and drawbacks. Homogeneous oxidation in the bulk during EF with Pt anode allowed for fast degradation of dyes but further intermediates might be accumulated in the solution. Heterogeneous oxidation at the anode surface during AO allowed for complete mineralization of organic compounds with low accumulation of intermediates but slower degradation kinetic of dyes. Therefore, combining EF with a nonactive electrode such as BDD appears as an appropriate solution to take advantage of both ways to generate simultaneously homogeneous/heterogeneous  OH for a quick removal of organic compounds.

Influence of the current on AO/BDD and EF/BDD process efficiency

The effectiveness for degradation and mineralization of AO/BDD and EF/BDD processes was then compared at 200 mA (8.3 mA cm -2 ) and 500 mA (21 mA cm -2 ) (Fig. 4). For AO/BDD, increasing the current supply strongly improved both discoloration of the effluent (i.e., degradation of the dye) and mineralization rate of organic compounds (Fig. 4a and4b). As the process was initially operated under current limitation conditions, increasing the generation of  OH strongly increased the effectiveness of the process during the first two hours of treatment.

However, the limiting current density was then reached as soon as the TOC removal rate reached around 40-50% for I = 500 mA (according to Eq. 7). Therefore, the evolution of TOC did not follow a pseudo-zero order kinetic since the process was then operated under mass transport control. The decrease of organic matter in the solution reduced the transport rate towards the anode and promoted dimerization of  OH (Eq. 10). Therefore, the mineralization rate decreased compared to that observed during the first 2 hours of treatment performed under current limitation.

2 BDD(  OH)  2 BDD + H2O2 [START_REF] Constapel | Degradation of reactive dyes in wastewater from the textile industry by ozone: Analysis of the products by accurate masses[END_REF] As regards to the EF/BDD process, higher current intensity increased reaction rates of O2 and Fe 3+ reduction, as well as  OH formation at the anode. A beneficial effect was therefore observed on both discoloration of the effluent and mineralization of organic matter (Fig. 4c and4d). However, the increase of the concentration of H2O2, Fe 2+ and consequently of  OH in the bulk can also promote several parasitic reactions (Eq. 11 -13).

Fe 2+ +  OH  Fe 3+ + OH - (11)
H2O2 +  OH  H2O + HO2  (12)

HO2  +  OH  H2O + O2 (13)
Overall, increasing the current accelerates discoloration kinetics and mineralization rates in all cases. However, it also has strong adverse effects on the energy efficiency of the process because of the promotion of (i) mass transport limitations for heterogeneous reaction at the anode and (ii) parasitic reactions of  OH generated in the bulk during EF process. This fact can be highlighted by the calculation of the energy consumption (EC) of the process, which strongly increases at high currents in both cases (Fig. 5). This figure shows that EC (expressed as kWh (kgTOC) -1 ) can be maintained almost constant when operating AO under conditions of current limitation (experiment at 200 mA), since the mineralization rate remains constant. Under mass transport limitation (i.e., at higher current densities), EC increases with time during AO because of the increase of wasting reaction (Eq. 10) when the amount of organic matter becomes low (Fig. 5a). The increase of the current intensity also has an adverse effect on cell potential (5.2 and 7.3 V at 200 and 500 mA, respectively), which has a direct impact on EC according to the Eq. 6.

As highlighted by the Fig. 5b, the EF/BDD process allows for decreasing EC thanks to the faster mineralization rate ascribed to the formation of oxidant species both at the anode and in the bulk. For example, after 4 h of treatment, the EC was 90 and 55 kWh (kgTOC) -1 for AO/BDD and EF/BDD processes, respectively. However, the EC was more affected by the treatment time in EF than in AO under current limitation since the oxidation rate in the bulk is a phenomenon depending on the concentration of organic compounds.

At 200 mA, the treatment during 4 h by the EF/BDD process resulted in 78% TOC removal with an EC value of 18 kWh m -3 . This value of EC is in the low range of values reported by Brillas and Martinez-Huítle (2015) [START_REF] Brillas | Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review[END_REF] while most of values reported in this review correspond to experiments performed on synthetic effluents containing dyes at concentration in the range 100 -500 mg L -1 . This comparison highlights that the use of BDD anode in EF process constitutes an efficient approach to remove organic pollutants in a non-selective way.

Similar conclusions were obtained from calculation of the current efficiency based on COD removal (CECOD). The CECOD calculated after 4 h of treatment by AO/BDD at 200 mA and 500 mA was 51% and 25%, respectively. The decrease of CECOD at high current intensity directly highlights the increase of wasting reaction (Eq. 10). By comparison, the CECOD after 4 h of treatment by EF/BDD at 200 mA was 78%. This higher value compared to the AO/BDD process highlights the benefit of the formation of oxidants in the bulk from the electrochemically generated Fenton's reagent.

Influence of initial pH of the effluent on AO process

The EF/BDD process requires operating at an optimal pH of 3 in order to maintain the concentration of the catalyst Fe 2+ in the solution. Inversely, the AO process can operate in a wider pH range since • OH are generated from oxidation of H2O. Therefore, the results presented in Fig. 6 aimed at studying the effect of initial pH of the effluent on the effectiveness of the AO process. There was not any significant difference in the mineralization effectiveness obtained at pH 3, 8 and 13.4 (natural pH of the effluent) (Fig. 6).

Protonation / deprotonation of organics in the solution did not significantly impact the overall mineralization yield. This behavior would also be a key advantage in case of pH fluctuation of the effluent to treat.

As the initial pH of the solution was 13.4, pH adjustment would represent an important cost for the EF/BDD process that may strongly counterbalance the lower EC. The AO process would clearly have the advantage to avoid this pH adjustment step. It is why recent researches are currently focusing on the development of heterogeneous catalysts for implementation of EF-like processes in a wider range of pH [START_REF] Ganiyu | Heterogeneous electro-Fenton and photoelectro-Fenton processes: A critical review of fundamental principles and application for water/wastewater treatment[END_REF][START_REF] Barhoumi | Kinetics of oxidative degradation/mineralization pathways of the antibiotic tetracycline by the novel heterogeneous electro-Fenton process with solid catalyst chalcopyrite[END_REF][START_REF] Labiadh | Complete removal of AHPS synthetic dye from water using new electro-fenton oxidation catalyzed by natural pyrite as heterogeneous catalyst[END_REF]. 3.6 Formation of chlorate and perchlorate at BDD anode One of the most important drawbacks of EAOPs is the formation of ClO3 -and ClO4 -from Cl - evolution at the surface of anode materials (Eq. 14). Particularly, the conversion of ClO3 -and ClO4 -occurs is promoted at the surface of BDD anode because it is able to catalyze both direct electron transfer and  OH mediated oxidation, as detailed in Eq. 15 and 16 [START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF][START_REF] Bergmann | The occurrence of perchlorate during drinking water electrolysis using BDD anodes[END_REF].

Cl - ClO - ClO2 - ClO3 - ClO4 - (14)
ClO3 - ClO3  + e - (15)
ClO3  + OH   HClO4 (16)
The results presented in Fig. 7 shows the evolution of the concentration of ClO3 -and ClO4 - during the treatment by AO/BDD and EF/Pt at different current intensities. Fig. 8 shows the evolution of the CE for oxidation of Cl -to ClO3 -and ClO4 -(CEClOx). On the contrary to CE for COD removal, increasing the current intensity did not reduce CEClOx. These results are consistent with the study of [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF] on the treatment of urine with BDD anode [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF]. Therefore, a very fast conversion of Cl -to ClO3 -was initially observed at 500 and 1000 mA. Then the concentration of ClO3 -decreased because of its further conversion to ClO4 -.

ClO3 -behaved as an intermediate compound with an evolution of its concentration depending both on (i) its formation rate from Cl -and (ii) its destruction rate with formation of stable ClO4 -. Thus, the concentration of ClO3 -started to decrease in the bulk when its destruction rate was higher than the formation rate. It occurred along the treatment due to the strong decrease with time of the concentration of Cl -reducing its formation rate. For example, 89%

of the initial concentration of Cl -was oxidized/transformed after 6 h of treatment at 1000 mA.

However, the CE for Cl -oxidation to both ClO3 -and ClO4 -did not significantly decrease over time during treatment by AO/BDD at 200 and 500 mA, which is also consistent with the previous study on the treatment of urine with BDD anode [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF]. A decrease was only observed at the highest current of 1000 mA, for which the concentration of Cl -reached the lowest values.

It is interesting to notice that the formation of ClO4 -started from the very beginning of the treatment by AO/BDD. By comparison, Pérez et al. ( 2012) previously described the evolution of chlorinated species at BDD anode in synthetic solution containing Cl -and NH4 + as well as in real landfill leachates [START_REF] Pérez | Assessment of the formation of inorganic oxidation by-products during the electrocatalytic treatment of ammonium from landfill leachates[END_REF]. In this case, the formation of ClO4 -in the synthetic solution only appeared after 2 hours of treatment at 40 mA cm -2 . Similar delay for formation of ClO4 - was reported during treatment of urine [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF]. The rapid formation of ClO4 -without any delay in the case of this textile effluent under study was most probably related to different conditions for competitive reactions, such as the absence of N-NH4 + and the different nature of organic compounds. For example, high concentrations of NH4 + in landfill leachates and urine initially involves competitive reactions of active chlorine with NH4 + for formation of mono-, di-, tri-chloramines, N2 or NO3 - [START_REF] Pérez | Assessment of the formation of inorganic oxidation by-products during the electrocatalytic treatment of ammonium from landfill leachates[END_REF]. [START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF] also highlighted that perchlorate formation might be inhibited from  OH scavenging by organic compounds, owing to the reduction of the availability of  OH for reaction with ClO3  in the vicinity of the electrode (Eq. 16) [START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF]. Such inhibition phenomenon was clearly depending on the reactivity of the organic compound selected as  OH scavenger.

The formation rate of ClO4 -at different current intensities can be compared during the first hour of treatment (during which the concentration of Cl -remains comparable for all experiments). Compared to the experiment at 200 mA, the concentration of ClO4 -formed at 500 and 1000 mA was multiplied by 3.1 and 8.3, respectively. These values are higher than the increase of the electric charge consumed, which was multiplied by 2.5 and 5 at 500 and 1000 mA, respectively. These results indicate that using low current intensity slightly reduced the formation of ClO4 -. It might be explained by the operation of the process under current limitation at 200 mA, which favors total  OH scavenging by reaction with organic compounds [START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF]. However, an additional test showed that further decreasing the current intensity to 50 mA (2.1 mA cm -2 ) did not further reduced the formation of perchlorate compared to the experiment performed at 200 mA for a similar electrical charge. By comparison to the study of Donaghue et al. ( 2013) [START_REF] Donaghue | Effect of Select Organic Compounds on Perchlorate Formation at Boron-doped Diamond Film Anodes[END_REF], much lower inhibition of ClO4 -formation was therefore observed in this study. The difference might be ascribed to the different pH conditions (4.4 vs 13.4), which was previously reported as an important factor for these reactions [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF][START_REF] Landolt | On the mechanism of anodic chlorate formation in concentrated NaCl solutions[END_REF][START_REF] Jung | An investigation of the formation of chlorate and perchlorate during electrolysis using Pt/Ti electrodes: The effects of pH and reactive oxygen species and the results of kinetic studies[END_REF], as well as by the different nature of organic compounds. These results highlight that the formation of ClO3 -and ClO4 -should always be monitored carefully during the application of heterogeneous EAOPs using non-active anode materials. They also emphasize the need to continue further research on ClO4 -formation and competition phenomena at the surface of these anodes.

The formation of ClO3 -and ClO4 -during the AO/BDD process was then compared with the EF/Pt process. It is interesting to notice that the formation of ClO4 -remained below the detection limit during the treatment of this effluent by EF/Pt process (Fig. 7). This configuration presents the crucial advantage of using an active anode material (Pt) that reduces the formation of ClO4 -because of the low accumulation of  OH at the surface [START_REF] Bergmann | The occurrence of perchlorate during drinking water electrolysis using BDD anodes[END_REF].

For example, the formation of ClO4 -was around 50 times lower when using Pt instead of BDD anode during treatment at 20 mA cm -2 of drinking water containing 230 mg L -1 of Cl - [START_REF] Bergmann | The occurrence of perchlorate during drinking water electrolysis using BDD anodes[END_REF]. The formation of ClO3 -was also strongly reduced in the configuration EF-Pt. Very low concentration of ClO3 -was obtained all along the treatment at 200 mA (below 0.5% of the initial Cl -concentration). Compared to BDD, the absence of oxidation of Cl -by  OH at the anode surface might reduce the formation rate. Moreover, a previous study from Jung et al.

(2010) highlighted that formation (and accumulation) of active chlorine was a key intermediate step for increasing ClO3 -formation rate at Pt anode [START_REF] Jung | An investigation of the formation of chlorate and perchlorate during electrolysis using Pt/Ti electrodes: The effects of pH and reactive oxygen species and the results of kinetic studies[END_REF]. Therefore, competitive reaction of active chlorine with organic compounds might also have reduced the formation of ClO3 -. The lower pH required for EF experiments (pH 3) also participated to reduce the formation of ClO3 -. In fact, alkaline pH was reported to be more favorable since HOCl participate in a lower extent to the formation of ClO3 -than OCl - [START_REF] Jung | An investigation of the formation of chlorate and perchlorate during electrolysis using Pt/Ti electrodes: The effects of pH and reactive oxygen species and the results of kinetic studies[END_REF]. Higher formation rate was obtained at 1000 mA since the chlorine demand might have been reached more rapidly at high current intensity (because of further formation of active chlorine). For example, ClO3 - appeared only after 2 h of treatment, most probably because of the preferential reaction of active chlorine with organic compounds at the beginning of the treatment. Once the chlorine demand is reached, active chlorine can accumulate in the solution and further reaction to ClO3 -can occur more easily. However, the CEClOx for Cl -oxidation was still much lower compared to the AO/BDD configuration at the same current intensity (Fig. 8). Therefore, using an anode material and operating conditions that prevent the formation of ClO3 -/ ClO4 - would be crucial for application of the EF process. Dimensionally stable anodes (RuO2/IrO2) might be a suitable low-cost alternative since it is an active material avoiding the accumulation of hydroxyl radicals at its surface [START_REF] Bergmann | The occurrence of perchlorate during drinking water electrolysis using BDD anodes[END_REF].

Reaction of active chlorine with organic compounds might also lead to the formation of organochlorinated by products, which are usually considered as toxic compounds. Stripping of the most volatile compounds might occur [START_REF] Zöllig | Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes[END_REF]. However, using an analytical tool such as the measurement of adsorbable organic halides (AOX) would be interesting for monitoring the fate (formation/degradation) of these compounds during the treatment. This issue should also be taken into consideration for optimization of process operation and assessment of the suitability of EAOPs for treatment of chloride-containing water.

Conclusions

This study allowed for understanding the impact of the generation of oxidant species homogeneously in the bulk (EF) or heterogeneously at the surface of BDD electrode (AO)

during the treatment of a real effluent coming from the textile industry. Both EAOPs achieved non-selective mineralization of organic compounds in the effluent. However, different behaviors were highlighted.

 Faster discoloration (i.e. degradation of dyes) kinetics was obtained by EF compared to AO thanks to more favorable mass transport conditions for reaction of dyes with  OH homogeneously generated in the bulk.

 Lower accumulation of by-products was obtained during AO because of complete combustion of dyes in the vicinity of the anode surface where high concentration of  OH is accumulated.

 The mineralization rate was constant with time for AO operated under current limitation condition (pseudo-zero order kinetic) while it decreased with time (pseudo-first order kinetic) for EF/Pt and EF/BDD processes.

 A lower EC and higher CE were achieved for EF/BDD compared to AO thanks to generation of oxidant species from both anodic and cathodic processes. EC increases with treatment time when mass transport limitations occur.

 Mineralization effectiveness remained constant during AO regardless of the initial pH of the effluent.

 Using non-active anode material such as BDD involves the formation of large amounts of ClO3 -and ClO4 -; the inhibition of perchlorate formation under current limitation was lower than the one expected from studies on synthetic solutions.

 Implementation of the EF process with active electrode (Pt) allowed for a strong decrease of the formation of ClO3 -and ClO4 -; the conversion even remained below 0.5% of the initial Cl -concentration when using low current intensity.

An important challenge is to control the evolution of chlorinated inorganic species, while achieving efficient removal of the organic load. These results highlight that future studies could focus on (i) the development of electrode materials with low reactivity for conversion of Cl -to ClO3 -and ClO4 -, (ii) the development of heterogeneous EF-like processes with active anodes that could be implemented in a wider pH range, and (iii) the combination of EAOPs with a post-treatment for the removal of these chlorinated inorganic compounds.

  Fig. SI 2; it is an aromatic compound containing two anthraquinone units and two amino

Table 1 - 39 ]Figure 1 -

 1391 Figure 1 -Comparison of the UV-vis spectrum of raw effluent (black line) and solution of Bezathren Dark Blue (BDB) dye (red line).

Figure 2 -

 2 Figure 2 -Comparison of mineralization kinetics of the raw effluent by different processes at constant current intensity of 200 mA (8.3 mA cm -2 ), including anodic oxidation with BDD anode (AO), electro-Fenton process with Pt anode (EF) and electro-Fenton with BDD anode (EF/BDD) (a). Linear regression analysis of mineralization kinetics following a pseudo-zero (b) and pseudo-first (c) order assumption.

  . The absorbance in the UV region decreased much less rapidly because of the formation of degradation by-products absorbing in the UV region. For example, Fig.SI-3shows the much slower decrease of the absorbance at 254 nm compared to 668 nm. The highest absorbance remains in the region of the lowest wavelengths (220 -240 nm), most probably due to the formation of short-chain carboxylic acids (e.g., oxalic acid and formic acid, which have maximum absorbance in this UV region). These final degradation by-products are slowly mineralized because of their lower reaction rate constants with  OH (e.g., absolute reaction rate constant of 1.4  10 6 M -1

Figure 3 -

 3 Figure 3 -Evolution of the UV-vis spectrum of the effluent during treatment by electro-Fenton process with BDD anode (EF/BDD) (a) and anodic oxidation with BDD anode (AO/BDD) (b). The slight difference of the spectrum at t = 0 was ascribed to the different pH of the effluent (i.e. natural pH for AO/BDD and pH 3 for EF/Pt).

Figure

  Figure (c) represents the comparison of the evolution of the absorbance at λmax = 668

Figure 4 -

 4 Figure 4 -Comparison of mineralization (a, c) and discoloration (at λmax = 668 nm) (b, d) kinetics during the treatment by anodic oxidation with BDD anode (c, d) and electro-Fenton with BDD anode (a, b) at 200 and 500 mA.

Figure 5 -

 5 Figure 5 -Evolution with time of the energy consumption for the treatment of the industrial effluent by anodic oxidation with BDD anode (a) and electro-Fenton with BDD anode (b) at I = 200 and 500 mA.

Figure 6 -

 6 Figure 6 -Comparison of mineralization kinetics of the effluent at different initial pH (3, 8 and 13.4, i.e., the natural pH of the effluent) during the treatment by anodic oxidation (AO) with BDD anode at 500 mA.

13. 4 )

 4 with BDD anode at (--) 200 mA (8.3 mA cm -2 ), (--) 500 mA (21 mA cm -2 ) and (--) 1000 mA (42 mA cm -2 ) and electro-Fenton process (pH 3) with Pt anode at (--) 200 mA and (--) 1000 mA. All molar concentrations were normalized as regards to the initial concentration of Cl -in the effluent.

Figure 8 -

 8 Figure 8 -Current efficiency for ClO3 -and ClO4 -formation from Cl -oxidation during the treatment by anodic oxidation process with BDD anode (natural pH of 13.4) at (--) 200 mA (8.3 mA cm -2 ), (--) 500 mA (21 mA cm -2 ) and (--) 1000 mA (42 mA cm -2 ) and electro-Fenton process with Pt anode at 200 (--) 200 mA and (--) 1000 mA.

Acknowledgments

This work is dedicated to the memory of the late Professor Adouby Kopoin of INP-HB (scientific supervisor) who unfortunately passed away in January 2021. Authors are grateful to the Service de Coopération et d'Action Culturelle (SCAC) of the French Embassy for providing financial support for the mobility of Alain Sié HIEN at Laboratoire Géomatériaux et Environnement. This work is part of the Public-Private Partnership Project funded by the Programme d'Appui Stratégique à la Recherche Scientifique (PASRES) and the African Centre for Technology Studies (ACTS) .


Charan Krishna

Jesse Donham

Alexander Wezel

ECO-SCHEMES IN EU MEMBER STATES COULD BENEFIT FROM MORE AGROECOLOGY

Forward

The new Common Agricultural Policy (CAP) entered into force at the beginning of 2023, which includes the new form of direct payment schemes for environmental, climate and animal welfare. While it is mandatory for all Member States to create these eco-schemes in their CAP strategic plans, it remains a voluntary measure for farmers. The EU has recommended that 25% of each member state's direct payment budget be spent on such schemes, which will be completely financed by EU funding under the 1st pillar and will not require co-financing from member states [START_REF] Lampkin | Using Ecoschemes in the new CAP: a guide for managing authorities[END_REF].

Direct payments have the potential to indicate a genuine way of implementing the principle 'public money for public goods', and since they represent a considerable part of a farmer's income, this could motivate them to adopt more sustainable practices. Further, this intervention could contribute significantly to EU Green Deal targets, and be a key step to transitioning to sustainable food systems. This policy brief will analyse each member state's strategic plan to determine which eco-schemes they have adopted and then identify which practices are truly agroecological and represent real progress to reach EU Green Deal targets.

They should cover activities related to climate, environment, animal welfare and antimicrobial resistance; They shall be defined on the basis of the needs and priorities identified at national/regional levels; Their level of ambition has to go beyond the requirements and obligations established under the baseline (including conditionality); They shall contribute to reaching the EU Green Deal targets.

Crop rotation with leguminous crops Mixed cropping -multi cropping

Cover crop between tree rows on permanent crops -orchards, vineyards, olive trees -above conditionality Winter soil cover and catch crops above conditionality Low intensity grass-based livestock system Use of crops/plant varieties more resilient to climate change Mixed species/diverse sward of permanent grassland for biodiversity purpose (pollination, birds, game feedstocks)

The policy context

In order to design their eco-schemes, each EU member state can choose from the agricultural practices defined by the European Commission (Directorate-General for Agriculture and Rural Development, 2021). There are no restrictions in the selection of agricultural practices but they need to meet the following conditions: 1.

2.

3.

4.

Agroecology, which is recommended among other production systems and practices, is a holistic approach to food production that combines ecological principles with social and economic considerations in order to improve the sustainability and resilience of agricultural systems (Gliessman, 2007;[START_REF] Wezel | Agroecology as a science, a movement and a practice. A review[END_REF]. There are nine specific practices proposed by European Commission (EC) which are considered to be following agroecological principles (HLPE 2019):

Improved rice cultivation to decrease methane emissions (e.g. alternate wet and dry techniques) Practices and standards as set under organic farming rules Other AEP group: If an eco-scheme adopts more than one proposed AEP, where it cannot be decided which AEP is the prevailing one, or adopts an agroecological practice that is not listed as agroecological in the EC's list [START_REF] Wezel | Agroecological practices for sustainable agriculture. A review[END_REF]. Non-AEP group: If an eco-scheme does not include any agroecological practice or if the eco-scheme cannot be attributed clearly.

An agricultural practice from the above list is henceforth referred as agroecological practice (AEP). If an eco-scheme adopts one of the AEPs mentioned in the EC list, it is grouped under AEP. Eco-schemes, that are not clearly associated with a specific AEP, are categorised into either of following two types: Diversity of eco-schemes in EU member states After months of discussions and significant processes of restructuring, the 161 eco-schemes designed and submitted by the 27 member states were approved by the EC. No restrictions were placed on member states on the number of eco-schemes that they had to design, hence the range adopted is diverse. For example, while Lithuania created 16 eco-schemes, countries such as Hungary, Ireland and The Netherlands have only one eco-scheme.

Nevertheless, the countries that designed only one scheme made it multi-dimensional and dynamic, including many sets of practices with unique payment models. Further, its important to note that the number of eco-schemes is not the most important determinant, as scale, funding and effective implementation can be much more relevant.

Although the EC did not explicitly mention the need for member states to adopt agroecological practices (AEP), all the member states except Cyprus have included at least one AEP in one or more of their eco-schemes, accounting for more than 68% of the total eco-schemes (111). Among this total, 53 eco-schemes have been clearly associated with one of the AEP listed by EC, while the others have been categorised by the authors as represented within Other-AEP group (58) and Non-AEP group (50). Figure 1 shows the number of eco-schemes per member state. Further, although many ecoscheme names provide clear intentions as to which set of practices are considered, only three member states (HU, LV, ES) have mentioned the term agroecology or agro-ecology directly in their eco-scheme names.

Figure 1: Number of eco-schemes adopted by the EU member states, categorized under type of eco-scheme.

Agroecological practices in eco-schemes Among the EU member states, 19 countries (including both regions of Belgium) have adopted at least one eco-scheme that is associated with an AEP. The list of EU countries and the AEP adopted by them are shown in Figure 2. The most favoured AEPs by member states (AT, BE-FL, BE-WA, BG, DE, ES, HR, IE, LU and SI) are Low intensity grass-based livestock system and Practices and standards as set under organic farming rules, whereas eco-schemes that incentivise farmers to practice climate-resilient crops or plant varieties was explicitly adopted by Greece alone. Further, Improved rice cultivation to decrease methane emissions was not implemented by any country.

Eleven eco-schemes, from 10 countries (BE-FL, BG, DK, EE, FR, GR, LV, LT, PT, SE), with 2 eco-schemes from Lithuania, have been identified under the category of AEP -Practices and standards as set under organic farming rules. Organic farming is mentioned directly in the eco-scheme name by all of these countries except for France, who mention environmental certification in their scheme name. Five member states (BE-FL, HR, EE, IT, LT) have introduced temporal diversification of crops through AEP -Crop rotation with leguminous crops in their eco-schemes. All of these member states, except for Latvia, have made it mandatory to include leguminous crops within their crop rotation. Whereas, spatial diversification of crops through AEP-Mixed cropping -multi cropping is encouraged by 6 member states (BG, HR, DK, FI, DE, LU). The main drivers that led these states to adopt the temporal or spatial diversity related AEPs re climate change (adaptation and mitigation) and the need to improve biodiversity (particularly for pollinators). On the other hand, the adoption of AEP -Cover crop between tree rows on permanent crops -orchards, vineyards, olive treesabove conditionality (AT, IT, LT, RO) seems to have been motivated by the protection of ecosystem services such as controlling soil erosion and encouraging pollinator species. Italy, for example, has created two such schemes under this category ('Pollinator-specific measures' and 'Weeding of tree crops'). Another AEP that focuses on covering soil with vegetation is Winter soil cover and catch crops above conditionality, which will be put into action in 7 countries (AT, BE-WA, DK, FI, LT, SI, SE). However, Austria has taken this a step further by dedicating two schemes to this purpose -"Greening of arable land -intercropping/catch crops" and "Greening of arable land -evergreen system".

Eco-schemes related to permanent grassland, with a hope to enhance biodiversity, are designed by 4 member states (DK, FI, DE, LU). Among these countries, only Finland has adopted two schemes for this AEP -Mixed species/diverse sward of permanent grassland for biodiversity purpose. Regarding reduction of livestock density in grazing areas, eight countries (AT, BE-WA, BE-FL, BG, HR, DE, LU, SI, ES) will be encouraging farmers to execute AEP-Low intensity grassbased livestock system. Croatia, Slovenia and Spain each have two schemes under this category. These eco-schemes are usually promoted in terms of "extensive management" of grassland and often limit stocking rates. Stocking rates relate to livestock density and the percentage of time spent on pastures. Finally, while some member states have mentioned having climate-resilient crops or practices that are climate-friendly as an option within an eco-scheme with another stated scope, Greece is the sole country to introduce a scheme specific to AEP-Use of crops/plant varieties more resilient to climate change.

Figure 2: AEP adopted in eco-schemes by EU member states.

Other AEP in eco-schemes Some eco-schemes do not focus directly on a specific AEP, however they appear to include practices that are closely related to them. For example, a member state may include an eco-scheme on crop rotations but they do not mention the necessity of 'leguminous plants' and thus cannot be categorised as an EC listed AEP -crop rotation with leguminous plants. Another example, is when countries support the use of mixed plant species for diversity purpose on arable land rather than grassland, making them unable to be grouped under AEP: Mixed species/diverse sward of permanent grassland for biodiversity purpose. Such eco-schemes are classified under 'Other AEP'.

Additionally, many eco-schemes mention more than one AEP, without a single AEP standing out as the prevailing one and therefore also classified under 'Other AEP'. For instance, CZ, HU, IE, and NL designed an eco-scheme with a set of practices, which include more than one AEP. Another example is Spain, who mentions two systems in one scheme 'Carbon farming and agroecology: rotations and no-tillage on irrigated cropland'. This eco-scheme is therefore associated both with AEP -crop rotation with leguminous plants and another non-AEP EC listed eco-scheme conservation agriculture (under carbon farming). The Latvian eco-scheme 'Support for environmentally and climatefriendly agricultural practices' provides support for adopting either 'crop diversification' or 'soil cover during the winter period'. These practices are directly associated with the AEP -Mixed cropping -multi cropping or Winter soil cover and catch crops above conditionality.

The final category is for the schemes that were chosen by member states that are not suggested by the EC as relating to agroecology, that actually are [START_REF] Wezel | Agroecological practices for sustainable agriculture. A review[END_REF], such as the management of landscape features, agroforestry or biological pest control.

Figure 3: Other AEP adopted in eco-schemes by EU member states.

Non-AEP in eco-schemes

The eco-schemes which do not fall under AEP or Other AEP, are placed in the Non-AE group. It is important to mention that while these practices were not determined as agroecological, it does not mean that they do not include agroecological elements, but it remains unclear what the true practices and scope of the scheme are. Alternatively, there are practices that are environmentally beneficial but that never the less do not relate to agroecology.

The non-AEP or production systems that were preferred are: Precision farming (BE-FL, CZ, SE), Carbon farming (BE-FL), practices beneficial for soil (BE-FL, BG, GR, MT, PT), practices related to GHG emissions (BE-FL, PT), Integrated Pest Management practices (BE-FL), and Husbandry and animal welfare plans (IT, LU, PO, RO). The practices listed by the EC as 'Other recommended practices' were also adopted by a few countries. Belgium-Flanders, for example, has designed an eco-scheme that adopts practices related to improving nutrient management by creating a 'Soil Passport' for the management of soil at the farm level. Portugal has introduced an eco-scheme for the 'Retention of water on permanent grasslands' that focuses on protecting water resources. While many member states have focused on reducing or banning the use of phyto-pharmaceutical products in their ecoscheme descriptions, some of them (BE-WA, BG, DE, GR, LV, LT, LU) have directly mentioned in the ecoscheme name the focus on reducing chemical pesticides.

Multi-dimensionality should be added to the design of all ecoschemes in order to encourage the implementation of multiple practices at once. This will create a holistic approach to farm systems rather than focusing on individual components of a system. Since one of the stated goals for the creation of eco-schemes is to implement climate-friendly practices and approaches, a strong emphasis could be given on the use of climate-resilient crop varieties, and more clarity could be created in what practices are specifically defined as climate-friendly. Some eco-schemes should be given a baseline incentive and on top of this, a premium for a more holistic implementation of all measures and practices. Proportionality should be ensured between the level of payment and the expected environmental benefits. More result-oriented measures should be included within ecoschemes to strengthen positive results, while still allowing flexibility to farmers in order for them to manage their own strategies.

The amount of subsidy received should be based on the complexity needed to implement certain management practices. Less demanding counterparts should not be more financially attractive than well-designed eco-schemes.

Maintain rigorous conditionality by not paying for what should be mandatory.

There has been a huge range of interpretations from each member state when deciding how eco-schemes should be created therefore, some basic guidelines for designing eco-schemes would be beneficial in the future. 1.

2.

3.

4.

5.

6.

7.

8.

Recommendations

The way forward Overall, due to their design flexibility, the approved eco-schemes are very diverse in terms of farming practices adopted and type of payment mechanisms, such as introducing points-based system to meet climate goals. Nevertheless, it remains clear that many ecoschemes have not been created with robust funding, clear targets or proven benefits, and risk to fall short of further Green Deal goals and not deliver environmental benefits.

When reviewing eco-schemes after the initial phase of implementation, it is vital that countries create clear objectives and roadmaps that are in line with other major EU legislations and agroecology, and to choose to go beyond the vague qualities of some current schemes.

Authors

Charan Krishna -ISARA, France Jesse Donham -Agroecology Europe, Belgium Alexander Wezel -ISARA, France More information about the H2020-Agroecology for Europe project can be found at: www.ae4eu.eu www.twitter.com/ae4eu_H2020 www.youtube.com/channel/ UCOsUVqM8tOhE28Gr2xcp2_w Additional policy briefs created by AE4EU can be found at: www.ae4eu.eu/agroecology-in-europe/policy-briefs/

The contents of this publication do not necessarily reflect the opinion of the European Union.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No101000478.