PROJECT DESCRIPTION
BACKGROUND
In the EU, contaminated leachate from landfills is commonly transported from the site to a biological sewage treatment plant for processing. However, in countries with low population densities and relatively small population centres, as is the case in Ireland, the availability of suitable treatment plants with excess treatment capacities can be low, and even when such plants are available prohibitive costs are incurred transporting leachate over long distances. The use of leachate technology at the time of the inception of the project throughout the Member States was not equitable and potentially levied an economic disadvantage on waste producers in countries with small population densities. Significant variations in treatment costs throughout the EU could have resulted in an unbalanced application of the polluter pays principle. Initial laboratory analysis, followed by the construction of a small scale pilot plant for the treatment of leachate at the central landfill in the country of Laois in Ireland, showed that leachate contaminant concentration could be reduced to acceptable discharge levels using peat filtration. Potentially, the technology could be applied on-site at landfills and reduce the need to transport leachate for treatment at sewage plants. On-site treatment systems, when used elsewhere, are mainly aerobic treatment systems and are costly to construct and operate.
OBJECTIVES
The project was a partnership between Laois County Council, Kerry County Council and the Environmental Protection Agency in Ireland to demonstrate the potential reproduction of an innovative, low-cost, low maintenance technology as a BATNEEC. The objective was to demonstrate that innovative peat technology could be used as best available technology not entailing excessive cost (BATNEEC) for onsite treatment of landfill leachate on both active and closed landfills. The project also proposed to demonstrate the technology to be ‘low cost, low maintenance’. The following discharge standards were required at each of the two sites to ensure protection of the receiving waters: BOD at 85 mg/l, ammonia at 15 mg/l. Target concentrations for treatment levels for three discharge parameters were given in the LIFE application as follows: Laois site: BOD at 47 mg/l, SS at 75 mg/l, ammonia at 15 mg/l; Kerry site: BOD at 23 mg/l, SS at 75 mg/l, ammonia at 15 mg/l.
RESULTS
The project constructed the first, full scale demonstration landfill leachate treatment facilities using peat as a treatment medium. The facilities were constructed on an active landfill at Kyletalesha in County Laois (receiving 24,000 tonnes per annum) and a closed landfill at Dingle in County Kerry. Trials at these two sites demonstrated that peat (particularly processed peat) can be successfully used to reduce concentrations of biochemical oxygen demand (BOD) and ammonia.It appears that the target concentrations were 10 mg/l for each of the above and these levels have generally been achieved. The process also lead to the removal of phosphates but it seems that the level of nitrates increased during treatment. Discharge of the treated liquid into the local river seemed to depend on the season and associated river flow, with nitrates being best taken up during dry weather flow, whereas ammonia and phosphates were best assimilated during wet weather and greater river flow. An additional benefit is that the process is very cost effective in comparison with the treatment of leachate at sewage plants. This process can be used in other countries and is particularly suited to those having peat deposits and where treatment is carried out in remote locations. Before the project started there was very little information on landfill leachates in Ireland. The project has resulted in a significant database of information on landfill treatment e.g. leachate chemical levels have been created. Some important environmental benefits have arisen from the project: - Full compliance with waste licence emission limit values for both treated leachate and receiving surfacewater; - Reduced ammonia discharges; - Compliance with the proximity principle (ie treatment of waste at source). Reduced pollution and erosion arising from transportation of leachate; - Recycling of heat generated by waste decomposition in order to heat the peat beds and improve ammonia removal; - Possibility of using wind power to generate the required power to pump leachate from the cells. The method is innovative and the project has successfully demonstrated the application of the technology. Two technologies have been developed – peatbed filtration and the telemetry control/recording system. Six companies have adopted part of the monitoring and control technology for use in their own pollution control systems. The project suffered from some delays, particularly with regard to construction works at the Kerry site and the modification and reconstruction of some of the peatbeds. The LIFE project treatment plant at Kyletalesha Landfill, Co. Laois, is a working plant, treating leachate to meet the emission limit values imposed in the conditions of the landfill’s waste licence. Demonstration and monitoring of the plant is therefore continuing beyond the duration of the LIFE project. The Environmental Protection Agency proposes to include design details of the Kyletalesha plant in a next “EPA Landfill Design Manual” due to be published in 2005.
