Pilot plant of forward osmosis to use the treated effluent in agricultural irrigation.Therefore, the goal of the project is to develop sustainable reuse systems that improve the quality of wastewater.
In Spain, the use of reclaimed water for different uses is regulated since 2007 (Royal Decree 1620/2007) and the minimum requirements for agriculture irrigation are regulated for harmonisation at the European level since 2020 (Regulation EU 2020/741) to promote water reuse and comply with the Green Deal EU policies.
Special water shortage in the Mediterranean region
One particular case is that of the riparian countries in south Europe and the north of Africa, which have high water scarcity, and at the same time have a water consumption in the agricultural sector that exceeds the 70-80% of total usage. In this case, reuse of wastewater presents a clear alternative to the shortage they experience in this particular resource.
Improvement in water availability is the PRIMA initiative’s goal (Partnership for Research and Innovation in the Mediterranean Area), that carries out research and innovation in this sector. In this framework, the proposal entitled Decision support-based approach for sustainable water reuse in agricultural production (DSWAP) has been approved.
The project’s aim, with the participation of the Institute of Environmental Assessment and Water Research (IDAEA), CSIC, is to develop modular, cost and energy-efficient wastewater treatment systems specifically designed for wastewater reuse in the context of crop irrigation that safeguard public health, environmental and soil quality and long-term agronomic sustainability.
Reducing contaminants, antibiotics and resistance genes
This initiative is relevant, as Josep M. Bayona, leader of the Environmental Pollution & Agriculture group from IDAEA-CSIC, points out that meanwhile “the health risk in a standard diet with vegetables irrigated by water containing contaminants is negligible, water with antibiotics and antibiotic resistance genes, even in low quantities, can have effects in both human health and ecosystems”.
The project consortium is coordinated by the Agricultural Research Organization of Israel and it is formed by 9 partners from 7 countries (3 SMEs and 6 research institutions, including the IDAEA-CSIC).
Scientists at IDAEA-CSIC are involved in the optimisation of a forward osmosis pilot plant to use the treated effluent in agricultural irrigation.
“The forward osmosis process can reduce the salinity content and contaminants present on wastewater, components that are not eliminated through conventional processes such as a biological treatment. Forward osmosis can eliminate nanoparticles, microorganisms (bacteria and viruses) and dissolved salts,” says Prof. J. M. Bayona.
Figure 1. The Forward Osmosis Unit receives water from two opposite directions: Wastewater, with low osmotic concentration, flows towards the upper side of the Forward Osmosis Unit. In the opposite direction, high-concentrated fertilizer flows towards the bottom side of the Unit. This difference of concentrations causes a water flow through a semipermeable membrane towards the high-concentrated fertilizer to balance osmotic pressures. The diluted fertilizer solution is finally used to irrigate water in a process called fertigation (irrigation with fertilizers).
The pilot plant has been designed and built by Apria Systems (Spain) and it has been set up in the agricultural station Agropolis (Universitat Politècnica de Catalunya) where different water with different qualities are used for crop irrigation. The goal is to treat wastewater with a fertilizer driven forward osmosis which allows to fertilize with treated water depleted of chemical and microbiological contaminants with low energy consumption. In fact, filtration is driven by the difference in osmotic pressures between feed (wastewater) and fertilizer (concentrated solution of a fertilizer). As Prof. J. M. Bayona states, “this new pilot plant consumes less energy than the conventional plants of reverse osmosis, which reduces the treatment’s cost.”
The aim of the project is to apply osmosis as a tertiary treatment (after the physical-chemical and biological treatments) in order to reduce the salinity in agricultural water crops that impoverish crops’ soil. By now the team of researchers are evaluating a process in which to generate treated water for crop irrigation with nutrients and a very low quantity of contaminants.
In this study, lettuce crops are irrigated with three watering lines, namely: reclaimed water, fertilizer driven forward osmosis and well water, which will be used as control due to its excellent physical-chemical and microbiological qualities. Because of this, well water enables researchers to make comparisons between the different watering lines used inside the project.
Water quality and crop productivity will be evaluated by the IDAEA-CSIC and the Barcelona School of Agri-Food Engineering from UPC. The contaminants of emerging concern in irrigation water, soil and crops will be studied by the University of Cyprus and plant stress indicators will be assessed by IDAEA-CSIC scientists from the Environmental Pollution and Agriculture, and Environmental Toxicology groups coordinated by Dr. V. Matamoros and Prof. B. Piña, respectively.
The antibiotic resistant genes will be tested by the Catholic University of Porto (Portugal) and viruses by the Lorraine University (France).
The final goal is to assemble all the data generated in a decision support tool that will allow to treat the data and help deciding which technologies are the most suitable to reach a certain water quality. This final task will be developed by the Technical University of Dresden (Germany).
This is how researchers expect to improve agriculture productivity, and thus safeguard the nutritional value and safety of watered crops with improved reclaimed water by sustainable treatment technologies.
Contact
Laura Díaz
Chemical Engineer.
Institute of Environmental Assessment and Water Research (IDAEA-CSIC)
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