PROJECT DESCRIPTION
BACKGROUND
Groundwater provides EU citizens with an important source of fresh water, but the quality of Europe’s groundwater supplies has been threatened by increased amounts of nitrates entering aquifers. Agriculture has been linked to this increase in groundwater contamination, which can result in serious negative impacts, such as increased water stress and risks to human health. The latter can be particularly problematic in parts of rural Europe, where residents still rely on wells for their drinking water.
OBJECTIVES
The main objective of the LIFE+ InSiTrate project was to demonstrate the potential of an innovative technology for tackling groundwater pollution from nitrates. This was aimed at restoring groundwater quality and improving the safety of drinking water in wells, especially for small communities without access to other freshwater sources. Specific objectives included:
RESULTS
LIFE+ InSiTrate demonstrated at pilot scale the feasibility of an in-situ bioremediation technology for nitrate-polluted groundwater that can be used to produce drinking water. Towards this goal, the project team developed an innovative tool based on mathematical modelling that can design and predict the performance of the in-situ technology in any aquifer. The constructed pilot plant produced drinking water in Sant Andreu de Llavaneres (Maresme, Cataluña) in Spain, and a key achievement was the life cycle assessment (LCA) of the technology from the technical, environmental and economic perspectives.
Preparatory activities established a working relationship with the Catalan Water Agency and the Town Council of Sant Andreu de Llavaneres; built on previous work characterising the pilot plant area in hydrogeological and chemical terms; and selected the organic matter for injecting into the aquifer to promote the bacterial activity for denitrification. Acetic acid was chosen as the key ingredient for injection.
Pilot plant specifications were based on an evaluation of environmental impacts (through LCA methodology), technical performance (lab scale experiments) and acquisition costs. The project team developed its decision-making tool to describe the performance of the in-situ bioremediation technology, and also used it to assist in the pilot plant design, for example, the selection of the number and locations of injection and control wells.
Pilot plant construction involved the drilling of two injection wells and three control wells, and a small house for the auxiliary equipment (e.g. pumps, acetic acid container and nitrate sensor). A control system was designed and implemented for pilot plant monitoring and adjustment. In May 2015, the pilot plant was activated with the controlled injection of organic matter into the aquifer. It operated for two years, during which several injection strategies were tested. Monitoring performed in the aquifer and the treated water showed that nitrate removal yields of 80% were achieved in the reaction area and of 20% in the extracted water. A total of 176 135 m3 of water was treated and 2 183 kg of nitrate was removed.
The LCA of the technical, environmental and economic viability of the InSiTrate technology was carried out using data from the pilot plant operation. This proved that organic requirements were lower than for other ex-situ biological technologies (e.g. 30% lower organic matter consumption compared to a denitrifying system), because the bacterial activity that is promoted does the denitrification. The environmental impact related to energy consumption was 98% lower for InSiTrate compared to ex-situ physical-chemical technologies, with similar results obtained for other impact categories, such as CO2 emission reductions (50-90% reduction), freshwater and marine eutrophication (60-90%), and freshwater and marine ecotoxicity (60-98%). From the point of view of the costs, InSiTrate could be cheaper than conventional technologies by up to 23%. For existing ex-situ technologies, such as ion exchange, reverse osmosis and electrodialysis, water needs to be first extracted, requiring a larger energy consumption and generating a saline residue that is either sent to landfill or dumped into the sea. InSiTrate technology minimises the space required for water treatment, as the reactor is the aquifer itself, and no saline is generated. Therefore, long term, the technology can reduce energy consumption, materials and waste generation, and minimise CO2 emissions. Producing in-situ drinking water from nitrate-polluted groundwater also improves water resource use and the ecological quality of rivers. It was concluded that InSiTrate technology could be implemented in many other areas in Catalonia (Camp de Tarragona, Plana de Lleida, Empordà, Garrotxa, Osona, Maresme, Vallès Occidental), Spain (Cuenca del Duero, Cuenca del Guadiana, Cuenca del Tajo) and around Europe (Belgium, Greece, Poland, Turkey, Slovenia and Denmark). The project team fostered the uptake of the technology, involved stakeholders and target groups in its implementation, and raised awareness of the nitrate problem in groundwater and the possible solutions. Nitrates over the safety limits for drinking water is a problem in many parts of Europe. By reducing nitrate-pollution in groundwater, the project helps implement the Water Framework Directive (2000/60/EC), the Groundwater Directive (2006/118/EC), the Nitrates Directive (91/676/EEC) and the Drinking Water Directive (98/83/EC).
From a socio-economic perspective, the project technology can provide an affordable alternative for municipalities with water supply problems due to nitrate pollution, which may be particularly important in tourist areas and areas with water scarcity. If the cheaper technology was implemented at a regional or national scale, it could also bring significant cost savings. Long-term social benefits include job creation at treatment plants, with the project estimating 100 new jobs at regional and about 500 jobs at the national level.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
