PROJECT DESCRIPTION
BACKGROUND
Modern agriculture focuses on increasing crop yield and its quality, which requires an intense use of water and fertilisers. One of the advances of modern agriculture is the use of soilless culture, which allows further increases in productivity. Open hydroponic systems, a type of soilless culture, are widely present in Europe. In The Netherlands, hydroponics accounts for more than 90% of agricultural production, while in other countries it is around 20%. However, in open hydroponic systems, drainage represents an environmental hazard. Drainage water is typically composed of nitrates (31%) and potassium (48%) applied as fertilisers, with the associated pollution and eutrophication of land and water.
The EU has addressed these concerns in several regulations – e.g. the Nitrates Directive (91/676/EEC) and Groundwater Directive (2006/118/EC), which were both integrated in the Water Framework Directive (2000/60/IEC). The Groundwater Directive aims to preserve groundwater as the most sensitive and the largest body of freshwater in the EU, and it identifies a maximum of 50 mg/l of nitrates while the soilless drainage waters contains between 500-1 000 mg/l.
Full re-circulation systems, also known as closed systems, are an environmentally friendly alternative to open hydroponic systems – but the percentage of European producers that use them in their greenhouses is very low, mainly because these systems need to be specifically designed and adjusted to the specific conditions where production is taking place.
OBJECTIVES
The LIFE DRAINUSE project aimed at designing, constructing and demonstrating a full re-circulation pilot system of drainage reuse that is easily adaptable to most agricultural scenarios in southern Europe. The project planned to test the pilot system in a 500 m2 greenhouse (0.05 ha) housing 952 tomato plants at the Experimental Greenhouse of CEBAS-CSIC, a governmental research facility in Murcia, southern Spain.
The pilot system proposed was expected to be able to collect drainage stemming from the normal irrigation of the tomato plantation. It then disinfects the drainage water and adjusts its nutrient concentration, pH and electrical conductivity with a view to making it re-usable in a new irrigation cycle. The project aimed also to propose a legal and regulatory framework for drainage recirculation to Mediterranean regulatory bodies in Europe.RESULTS
The DRAINUSE project tested dry anaerobic digestion (AD) technology under thermophilic (55°C) and mesophilic (35°C) conditions as an effective way of treating sewage sludge from wastewater treatment plants. For this purpose, the project team designed and constructed a pilot plant to install a full recirculation system,. However, the team were not able to demonstrate the replicability, transferability and marketability potential of the project approach.
The main outcome was showing that full recirculation system for soilless culture was technically feasible and environmentally beneficial. The project team also concluded that revenues from implementing the system could potentially cover the operational costs. The main reason, however, for installing the DRAINUSE system relates to the provision new water source of higher quality (recirculated water), for agricultural application mostly, thus avoiding the exploitation of aquifers and groundwater. This new water source could therefore serve areas where supply in scarce.
The project also helped create a legal and regulatory framework for drainage recirculation to Euro-Mediterranean regulatory bodies. It proposed four areas for joint action at regional, national and European level:
- Raising awareness among farmers about the ‘zero discharge’ system;
- Zero discharge target in 2030;
- Promoting financial aid that facilitates the transition to closed systems; and
- Obtaining benefits for users of closed systems in agriculture
These action points were presented to regional authorities at a series of meetings held during the project as well as at several events in order to reach other regulatory bodies at national and European level. In response to the high levels of eutrophication of water in the Mar Menor area, the Spanish region passed legislation (Urgent measures to ensure environmental sustainability in the Mar Menor environment) that prohibits the use of high soluble fertilisers in soil crops without a recirculation system.
Quantifiable environmental results included:
- 41% reduction in water consumption in a closed system, compared to an open system, from a annual consumption of 22 813 m3/ha to 13 457 m3/ha;
- 60% reduction in fertiliser consumption in terms of nitrogen, 12% in terms of phosphorus and 48% in potassium;
- Elimination of dumping of fertilisers into the medium passes, thus potentially avoiding around 749,813 tonnes of waste in Europe annually; and
- Reduction in CO2 emissions by 36 928 kg CO2-eq/kg per hectare annually (potential annual saving over 152 000 ha of horticultural land of 5 613 056 tonnes of CO2-eq.
Socio-economic results included:
- Decrease in cost due to the reduction of water and fertiliser use: water use effeciency increased from 7.2 kg of tomato/m3 at the beginning of the project to 20 kg of tomato/m3 at the end, while the cost of nitrogenous fertiliser were reduced from €9 695 per hectare €3 296/ha, resulting in total annual savings of €18 056 per hectare;
- Increase in annual crop yield from 165 000 kg per hectare at the start of the project to 368,827 and 373 353 kg/ha in the second and third cycle; and
- Job creation due to the need for qualified managers for the installations and two to three operators of the recirculating system
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
