News:
Mechanical biological pre-treatment processes – a main topic at the SARDINIA 2007
In a well attended session – lead by Kai-Uwe Heyer - the pro´s and con´s of the mechanical biological pre-treatment were discussed, based on comparative studies and examples from existing MBT plants in Germany.
 Panel of experts (from the left): Knox (UK), Heerenklage (GER), Heyer (GER), Martel (FRA), Rettenberger (GER) |
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| K. Knox |
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| J. Heerenklage |
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| J-L. Martel |
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| G. Rettenberger |
- MBT consumes energy, whilst thermal treatment is a net exporter of energy.
- MBT is a net emitter of carbon dioxide whilst incineration is carbon neutral.
- The leachate and gas management burdens of MBT residuals are similar to those of untreated MSW.
- The low permeability of MBT residues make it unlikely that they could be flushed to reach Final Storage Quality (FSQ) within a sustainable period.
- The gas management burden of incineration residues is negligible.
- The long term leachate management burden of incinerator residuals is difficult to
quantify and needs further study.
Two practical examples of existing MBT plants were given by Mr. Martel, Center of Research on Water & Environment (France) and Mr. Heerenklage, Hamburg University of Techology – Institute of Waste Resource Management.
Mr. Martel showed some aspects of optimizing the MBT plant Crövern near Leibzig (Germany) which is scheduled for a capacitiy of 300.000 tons per year. After one year of full operation phase, the results and experiences are as follows:
- the mixed entering waste created some problems for space management
- some improvements of primary shredders were done, especially focused on coarse fractions
- the adjustment of trommel mesh was very depending on pre-shredders efficiency
- the „Refuse Derived Fuel“ refining was the key point of the process commissioning
- the maturation was shown essential to reach leachate „Total Organic Carbon“ target values
- the refining stage was proven useless due to very efficient upstream treatment
Mr. Heerenklage reported about the results of a mechanical biological pre-treatment of residual waste according to the principle of fermentation and subsequent aeration in the slurry phase, which was untertaken for the first time at full-scale in Lübeck (Germany) regarding the influence of different temperatures (35 °C, 40°C and 45°C) in the biochemical conversion processes.
Prof. Rettenberger (Germany) gave a detailled look on a new concept for a technology that separates municipal waste into a fraction with low water content and a fraction with higher water content for a optimized thermal or biological use. This low cost separation process is pressing municipal waste at high pressure of up to 1.000 bars into a pressure chamber and was realised in Alessandria (Italy) and Kaiserslautern (Germany)
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