PROJECT DESCRIPTION
BACKGROUND
Although recycling rates have increased in Europe much waste is still landfilled, especially in Mediterranean and Eastern European countries. Landfills present long-term threats to soil, air, groundwater and surface water. This is mainly due to leachates, the liquid fraction continuously produced from solid waste that is dispersed when rainfall percolates through it. Approximately 10 m3 of leachate is generated per 115 tonnes of solid waste, and landfills can keep producing leachates up to 50 years after their closure. Although leachate composition varies, it is invariably hazardous to some extent – with potential ecotoxicological effects on terrestrial ecosystems and humans.
In the absence of on-site treatment, leachate is circulated back into the waste, resulting in a more concentrated liquid that has a bad odour and attracts disease-spreading flies, creating bigger potential ecological and health risks and unpleasant working conditions. Without treatment, the leachate is also transported to sewer systems or wastewater treatment plants (WWTPs). Due to its high organic and ammonium concentrations, leachates cause extra loading in treatment plants, requiring additional chemical and energy consumption to comply with effluent limits.
Moreover, due to the high metal content in leachate, the sludge generated may not be suitable for agricultural applications. The problems are most acute in smaller WWTPs, where leachate is less diluted with municipal sewage. Leachate treatment techniques remain expensive and technically inefficient.
OBJECTIVES
The LIFE LEACHLESS project aimed to demonstrate the technical and economic feasibility of an innovative and cost-efficient technology for leachate treatment, based on solar evaporation/condensation and forward osmosis. The project prototype aimed to have a treatment capacity of 15 m3/day of leachate and were tested in Lanzarote (Spain) and Athens (Greece).
The new technology permitted the on-site treatment of leachate, removing 100% of the pollutants (including emerging pollutants) and avoiding costly and energy-consuming effluent transport to municipal WWTPs. The final solid residue (sludge) was used in the manufacture of ceramic products as a waste-to-resource strategy.
The project promoted water resource management in line with the Water Framework Directive by enabling managers of landfills and waste treatment centres to achieve good qualitative and quantitative status for effluents. By reducing energy consumption and valorising the sludge, the project was fully in line with the objectives of the EU 7th Environment Action Programme (EAP) regarding the transformation of the EU into a resource-efficient and low-carbon economy; the EAP also prioritised the more efficient use of water resources.
Finally, the project improved the operation of landfills and reduced their associated environmental impacts, thus contributing to the Landfill Directive.
RESULTS
The LIFE LEACHLESS project has achieved its main objective, which is to demonstrate the technical and economic feasibility of an on-site leachate treatment model using a novel and profitable technology that combines solar evaporation/condensation with forward osmosis. The energy consumed in this process comes 100% from renewable energy sources (solar evaporation/condensation and biomass boiler), which minimise the carbon footprint of the process.
During the project implementation, the LIFE LEACHLESS demonstration plant treated approximately 12m3 of leachate per day at two demonstration sites (eight months in the Zonzamas Environmental Complex in Lanzarote (Spain) and four months in the Ano Liosia landfill in Athens (Greece).
The LEACHLESS technology separates the leachate into two products: a final liquid effluent that can be used as irrigation water or for cleaning operations of equipment and facilities, and a semi-solid stream as a by-product that, due to its properties, can be used as a raw material for the formulation of materials for the ceramic industry.
The LEACHLESS technology provides a high water-recovery performance (85% to 95%) with a low net energy consumption (30 to 35 kWh/m3). In addition, the leachate treatment operating cost is reduced by up to 70-80% in comparison with a traditional process. The need to transport leachate to municipal wastewater treatment plants (WWTPs) is eliminated. This eliminates the associated transport costs and the risk of emerging contaminants from leachate entering the general water circuit. Moreover, an 80% reduction of CO2 emissions associated with leachate streams from waste disposal in landfills or waste treatment centres is achieved.
Thanks to the results obtained, this new technology is ready to be included in the market. The LIFE LEACHLESS demonstration plant will remain installed in the Zonzamas Environmental Complex (Lanzarote) as a demonstrator for a couple of years more after the end of the project. The plant will be ready to be transported at any time to another company in the sector that wants to perform "in situ" leachate treatment using LIFE LEACHLESS technology.
In relation to environmental policies, the treatment of leachate generated in landfills minimises their environmental impact and contributes to the increase of landfills adapted to the Directive 1999/31/EC on the landfill of waste. The project results will also contribute to the implementation of the Water Framework Directive 2000/60/EC, facilitating landfill and waste treatment centre managers in achieving improved qualitative and quantitative status of their effluents.
