IWWG Working Group on
LANDFILL MODELLING
Chair: Andreas Haarstrick
Identification of the purpose of modelling landfill processes, as well as the application of detailed model solutions, has assumed increasing significance. Modelling is now acknowledged as representing a powerful tool capable of solving future landfill problems. This includes the construction of bioreactor landfills, the monitoring and risk assessment of conventional landfills either during the operating, post-closure or aftercare stage, and prediction and control of long-term emission behaviour.
With respect to the post-closure and aftercare period, scarce experimental or field data are available. This is the point at which appropriate models could improve the understanding of the ongoing processes and transfer model-based experience into technical solutions aimed at improving conditions for biodegradation, leachate transport, water distribution, etc.
Recent developments and improvement of models describing complex processes within the landfill structure have led to an increased acknowledgement of their utility, demonstrating their suitability for use in solving future landfill problems. This aspect becomes even more relevant when applied to the construction of bioreactor landfills or to the monitoring and risk assessment of conventional landfills either during the operating or aftercare stage.
Generally speaking, a window onto future landfill behaviour (starting with the post-closure treatment) could be opened to extend historical data from existing landfills (monitoring data) needed for model calibration, supported by model predictions that are continuously evaluated and reviewed using current incoming monitoring data.
Considering these different, complex aspects of landfill modelling and the joint objective of creating powerful modelling tools, the setting up of an IWWG Task group on Landfill Modelling has been proposed to unite international expertise and knowledge, to define and homogenise the state of the art, and to disseminate experience to other researchers and the public.
The Task Group will aim to prioritise and encourage the development of the following issues related to modelling:
- Waste characterisation (properties and processes)
- Behaviour of landfills and long-term emissions (biodegradation, waste mechanics)
- Landfill bioreactors
- Waste stabilisation (indicators, criteria)
- Landfill risk assessment (risk for ambient areas and the groundwater)
- Data management (management of raw, edited, and simulated data)
In view of the potential benefit to be gained and practical work to be performed, the LMTG could focus on the following specific issues:
- Proposals for setting up of the Task Group
- Identification of gaps in research
- Model solutions to specify, for instance, long-term landfill emissions
- Models to assist landfill operators in optimising monitoring procedures or technical solutions reducing after-closure and/or aftercare periods
- Recommendations for regulators based on current knowledge
During a meeting in April 2009 in Toulouse, France, the INSA School of Engineering has proposed to be the intermediary between the Sustainability Landfilling Task Group SLTG and the LMTG. This relates mainly to behaviour of landfills and long-term emissions. It has been established that tasks performed by the two groups do not overlap but elicit a complementary interaction between SLTG and LMTG.
Complementary interaction between SLTG and LMTG
It was concluded that the prevailing questions that concern both task groups are:
- What will be the future quality and quantity of leachate and gas emission?
- When will the final storage quality (threshold value) be reached and how high is the remaining risk?
Another cooperative venture is constituted by the setting up of a mutual database to communicate raw and edited data. Generally, the SLTG focuses more on definitions, criteria, and technical improvements than on theory, process models, simulation, and model output. The LMTG requires input from the SLTG in terms of what is needed and what conditions need to be met. The topics that both TG's address require dedicated expertise and, although operating independently, the chairs will continue to communicate over the distribution of tasks. Work carried out may converge to some extent with activities performed by the IWWG Leaching Task Group. These convergences will be discussed during the Sardinia 2009 Conference.
The following scientists will initially coordinate Task Group activities:
- R. Beaven, University of Southampton, UK
- A. Haarstrick, University of Braunschweig, Germany
- J. McDougall, Napier University, Scotland, UK
- K. Münnich, University of Braunschweig, Germany
- J. White, University of Southampton, UK
The Task Group is chaired by Andreas Haarstrick. Prof. Haarstrick is coordinator of the landfill research project “landfill modelling and analysis of chemical and biological reaction processes”. Since 1998 he is head of the environmental bioprocess working group at the Technical University of Braunschweig at the Institute of Biochemical Engineering. From 2000 to 2004 he was assistant professor and since 2005 he is working as associate professor at the same institute. His main fields of interest are fluiddynamics, transport processes in porous media, modelling of degradation processes in landfills and their long-term emission behaviour.
Andreas Haarstrick, chairman of the Landfill Modelling Task Group
The Task Group will convene for the first time during the 12th International Waste Management and Landfill Symposium, Sardinia 2009, where the organisation of the Group and its driving forces and goals will be discussed.
Prior to the conference, delegates are invited to register in the IWWG Landfill Modelling Task Group by contacting Andreas Haarstrick (e-mail: a.haarstrick@tu-bs.de) or Richard Beaven (e-mail: richard.beaven@virgin.net) stating whether they are practitioners or researchers and whether they might be able to attend the meeting during the Sardinia Symposium. Furthermore, candidates will be asked to express their opinion about the activities of the Landfill Modelling Task Group, the benefits from the group membership and the outcome for regulators and landfill operators.
LANDFILL MODELLING TASK GROUP MEETING:
Next LMTG Meeting in scheduled on Friday 16 April 2010 at ADEME in Paris. For further information please contact: a.haarstrick@tu-bs.de