by Simos Malamis, Stavroula Kappa, Eleni Nyktari and Constantinos Noutsopoulos (National Technical University of Athens)
The work of the HYDROUSA project is revolutionising the water value chains in the Mediterranean region. We use innovative nature-based solutions to utilise disregarded forms of water to combat water scarcity and to support tourism and agricultural activities.
Global environmental change is closely linked to the water crisis. Undoubtedly, climate change is amplifying water cycle fluctuations, increasing the probability of extreme weather-related events, reducing the predictability of available water resources, reducing global biodiversity and threatening one of the fundamental human rights: the right to safe drinking water and sanitation [1-2]. The Mediterranean region is considered to be one of the world’s hot-spots in terms of water scarcity; it is characterised by irregular allocation between water demand and water supply, both spatially and temporally. Agriculture is the largest consumer of water in the region (> 72% of total consumption), while other sectors, such as the tourism industry, exert additional seasonal pressure and significantly decrease the available water resources . In order to balance this increased demand, desalination plants have been established, which increase energy consumption locally, while the resulting brine by-product is not valorised and is released untreated into marine ecosystems. The gradual implementation of the Water Framework Directive and the Urban Waste Water Treatment Directive have improved water/wastewater management, resulting in the development of some infrastructure. However, several Mediterranean areas still discharge inadequately treated wastewater into the sea. Consequently, the region faces significant issues in terms of water resources and biodiversity management.
To address these challenges, an EU Horizon2020 Innovation Action project (call topic CIRC-02-2016-2017 - Water in the context of the circular economy) HYDROUSA was launched in July 2018 to reimagine a water resilient economy, mitigate climate change and reform the agro-food system. Its consortium consists of 28 highly competent organisations involved in water/wastewater management, agricultural activities, ICT and business/marketing, dissemination/communication spanning throughout the whole water supply chain, consisting of universities, research institutes, SMEs, NGOs, municipalities and water utilities.
The main objective of HYDROUSA is to set up, demonstrate and optimise on-site, innovative nature based solutions (NBS) for the management of a variety of water streams, including wastewater, rainwater, groundwater, atmospheric vapour water and seawater to produce valuable resources (energy and nutrients) and high quality water, which can then be used to enrich the domestic water supply and valorised to increase agricultural production and boost the economic activities of water-scarce Mediterranean areas. HYDROUSA aims at closing all water loops at local level, taking advantage of local resources, promoting the concept of decentralised on-site water, materials and energy conservation, treatment and reuse (Figure 1).
Figure 1: HYDROUSA water loops implemented in the Mediterranean.
HYDROUSA implements a number of innovations related to technology and services. Innovative nature-based solutions that are characterised by low energy and carbon footprint are demonstrated at full scale in three Greek islands (Tinos, Mykonos and Lesbos). In addition, HYDROUSA solutions are assessed in 25 early adopter cases in other Mediterranean coastal areas and islands and at several water-stressed rural and peri-urban non-Mediterranean areas. The innovations of HYDROUSA project include the:
- demonstration of biodiverse constructed wetlands (CWs) to treat wastewater and produce reclaimed water. HYDROUSA´s CWs are richer in diversity resulting in more resilient ecosystems. Furthermore, pilot scale electroactive constructed wetlands are demonstrated to produce energy from sewage, resulting in much lower footprint requirements
- integration of grey with green infrastructure (anaerobic treatment by upflow anaerobic sludge blanket coupled to vertical flow constructed wetlands) to treat wastewater and produce reclaimed water that is safe to reuse and rich in nutrients to be valorised for plant growth. Energy is produced from wastewater through the anaerobic treatment of sewage
- demonstration of sludge treatment wetlands coupled with composting to treat anaerobic sludge and produce high added value compost
- rainwater/stormwater harvesting, storage into the aquifer to produce service water and agricultural irrigation water
- the use of advanced techniques to monitor water quality and quantity. A low-cost water monitoring system has been developed and applied, which measures and records water quality, water quantity and meteorological data, integrating water treatment with agriculture
- development of an agroforestry system: HYDROUSA has developed a biodiverse agroforestry system, based on the output of the local community, which is fertigated/irrigated with reclaimed water obtained from the treatment of sewage. It consists of trees and shrubs as superfood providers, and several local varieties of vegetable crops and aromatic plants as added value products
- innovative and low-cost seawater desalination: The biomimicry Mangrove Still system has been developed to recover freshwater from seawater via a process of evaporation and condensation run by sunlight
- defining new circular economy financing models: In HYDROUSA, different business cases for each technology will be identified to build innovative business models that map costs, resulting in economic, social, human and natural benefits.
HYDROUSA has developed “a community of water allies''. Members of the local community (farmers, water utilities, etc.) along with researchers and other stakeholders have a dominant role in the project as they are transformed in key actors, co-developers and evaluators of water solutions and services. This is being accomplished through the implementation of various participatory methodologies, such as co-creation and citizens' science activities. A successful case that has already been implemented is the design of the low-cost water monitoring systems of HYDROSUA project, which was based on the specification and requirements of the local users through the conduction of co-creation workshops and one-to-one interviews.
HYDROUSA receives funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 776643.
 V. A. Tzanakakis, et al.: “Challenges and opportunities for sustainable management of water resources in the Island of Crete, Greece,” Water (Switzerland), vol. 12, no. 6, 2020, doi: 10.3390/W12061538.
 UN-Water policy brief ‘’ Climate change and water’’, UN-Water’s publications, pp:1-8, 2019
 M. Milano, et al.: “Current state of Mediterranean water resources and future trends under climatic and anthropogenic changes,” Hydrological Sciences Journal, vol. 58, no. 3, pp. 498–518, 2013, doi: 10.1080/02626667.2013.774458.
National Technical University of Athens, Greece