Sustainable landfill technology

Background

More than 90% of all solid wastes generated world - wide are deposited on land whereas approximately 68% of the generated Municipal Solid Waste (MSW) is landfilled. In the EU28 approx. 42% of the generated MSW has been landfilled in 2012. Solid waste disposal sites (SWDS, ranging from open dumps to sanitary landfills) as such cannot be considered a sustainable disposal option. During waste deposition, closure and post closure SWDS are generating emissions, which do have a negative impact on the environment and potentially represent a threat to human health. In particular, in the course of anaerobic decomposition of waste organic compounds within a landfill, landfill gas (LFG) mainly consisting of methane and carbon dioxide is generated. If not captured and adequately treated, released LFG contributes towards climate change. Polluted leachate on the other hand potentially contaminates the soil and ground water.

Research fields and objectives

Landfill emissions as leachate and landfill gas (LFG) have to be controlled and treated until their amount and quality has reached a level that is environmentally acceptable. There is a great discussion in Germany when this will be the case. Moreover, landfills are one of the major contributors to the generation of greenhouse gases. Landfill aeration is the most promising methodology for the fast and sustainable reduction of the emission potential under controlled boundary conditions. In this connection the following research activities are carried out at the DepoLab 4.0 at IUE:

Process control

The accelerated bio-stabilization of landfills can be based on different aeration concepts. In general active and passive aeration concepts may be applied. For the active aeration concepts compressed air is injected into the waste mass. In accordance with the adjusted pressures the concepts are further distinguished into high and low pressure aeration. By contrast, passive aeration concepts are based on negative pressures induced inside the waste mass, leading to an introduction of air through the landfill surface or other technical installations (wells, pipes, etc.). The research objective at IUE is to define specific fields of application for the different concepts including an optimization of the process technology. [Selected publication]

Climate protection

Climate protection is a global task and the reduction of Greenhouse Gases (GHG) represents one of the major challenges of today. Methane from former waste disposal sites as well as sanitary landfills contributes significantly to the global anthropogenic methane emissions. Landfill aeration represents a reasonable amendment to landfill gas collection and utilisation (from anaerobic landfills). During the aeration methane production is gradually reduced and the methane generation potential (i.e. the amount of biodegradable organic compounds) is sustainably minimized. In combination with a suitable off-gas treatment (thermal oxidation) GHG emissions can be reduced by more than 90% in comparison with an anaerobic landfill. Therefore, landfill aeration is an effective contributor towards climate protection. The major research objectives at IUE are the balancing of emission occurring before, during and after aeration in order to enhance the efficiency of the measure. [Selected publication]

Costs and long term behaviour

Measures for the bio-stabilization of landfills involve investment and operation costs. Therefore, emphasis is laid on cost reductions which may be realized in different fields. Based on the provisions of the German landfill ordinance successfully stabilized landfills may be top-covered by sealing systems with only a single sealing element (instead of the double liner which is required for non-stabilized landfills). Moreover, long term cost reductions are expected by the potential reductions in the duration and extent of landfill aftercare. The latter is connected with less intensive LFG management and a leachate treatment which can be adjusted to the enhanced quality (i.e. lower level of pollution) of leachate. The research objectives at IUE cover the prognoses of leachate long term quality, assessment of stabilization periods as well as amounts and quality of residual emissions from bio-stabilized landfills, including treatment options. [Selected publication]