PROJECT DESCRIPTION
BACKGROUND
Nutrients such as nitrogen (N) and phosphorus (P) are essential for plants to grow. They are often used as fertilisers to guarantee higher yields in agriculture. However, the increasing demand in food production has resulted in an increased production and the accompanying use of fertilisers, which is associated with increased water pollution (nitrates and phosphorus in surface waters can lead to eutrophication), air and soil pollution, and negative impacts on human health (nitrate concentrations above 50 ppm are harmful to babies, foetuses and people with health problems).
At a global level, N and P already exceed safe levels, representing a severe threat to nature as well as to the climate. Europe makes a considerable contribution to this form of pollution. The European Environment Agency (EEA) estimates that the limit for N losses is exceeded by a factor of 3.3 and the limit for P losses by a factor of 2 in Europe.
According to the last EEA report on the status of Europe’s waters, nitrates were the main pollutant in the EU, affecting over 18% of the area of groundwater bodies, with agriculture being the main cause.
Despite efforts made to prevent nitrate pollution, there are still infringement procedures against several Member States by the European Commission, including Belgium, Germany, Italy and Spain. As a result, in 2020, Spain reviewed and designated Nitrate Vulnerable Zones (NVZs), including Gandía and four of the eight Canary Islands. Malta is a similar case, with the whole island having been designated as a NVZ in 2008 after an extensive and detailed groundwater quality monitoring programme.
OBJECTIVES
The main objective of the LIFE ELEKTRA project is to reduce the concentration of nitrates in the entire water cycle, co-creating an integrated, innovative, simple, economical, sustainable and transferable system. The project system will be based on the use of electrochemical denitrification to remove nitrates and convert them into nitrogen gas, while enhancing the decarbonisation of the process through renewable integration analysis focused on photovoltaics and hydrogen and other optimisation means.
The project’s specific objectives are to:
Validate electrochemical denitrification technology applied to the treatment of streams with high nitrate concentrations, transforming nitrates to nitrogen gas that is emitted into the atmosphere without impacting the environment.
Valorise the waste produced during the pre- and post-water conditioning stages of electrochemical denitrification, forming a process that will approximate Zero Liquid Discharge into the environment.
Demonstrate the validity of a system that allows the hybridisation of renewable energies to cover as many of the energy needs of the process as possible, reducing greenhouse gas emissions through the decarbonisation of the process. To that end, the design and implementation of a stage for capturing, concentrating and storing gaseous hydrogen, a by-product produced in the denitrification process, is envisaged. This high purity hydrogen stream will be used to feed a fuel cell. Furthermore, a photovoltaic solar energy will be coupled to the denitrification process as a source of energy.
Demonstrate the replicability of the proposed solution by addressing three case studies, located in Spain (Valencia and Canary Islands) and the Republic of Malta, each with different characteristics, but with the same challenge.
Increase the technology readiness level (TRL) of the solution proposed from the current TRL 5-6 to TRL 8.
RESULTS
The project’s expected results are:
The avoidance of discharging approximately 1,460 m3/year of polluted water (4 m3/day) currently generated at Gandía reversible electrodialysis plant. In addition, an existing pilot plant will be adapted to treat 0.5 m3/day over six months (91m3 in total) at La Aldea (Gran Canaria) and at Bingemma Pumping Station (Malta).
A decrease of Calcium (Ca) concentration 750 mg/l up to 10 mg/l with the first step of the process (softening through ion-exchange technology). This will enable the production of more than 1,000 kg/year of Ca. The obtained Ca will be used in the project process, specifically in the post-treatment demineralisation step.
A removal of 85% (nearly 500 kg) of nitrates, converted to nitrogen gas, after concentrating the nitrates with reverse osmosis (from 420 ppm to 1,600 ppm).
Production of energy from two sources: firstly, with the hydrogen produced through the process (10.88 KWh/day and nearly 4,000 KWh/year) and then with photovoltaic panels (26 KWh/day and nearly 9,500 KWh/year). The total production (nearly 13,500 KWh/year) has been estimated as 30% of expected project consumption.
The avoidance of the emission of more than 1,850 kg of CO2/year, considering a ratio of 138g CO2 equivalent for every kWh of electricity consumed (mix energy data for March 2023 in Spain).
