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International Review of Waste Management Policy - Department of ...

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and Komilis and Ham, all <strong>of</strong> whom investigated the link between the biochemical<br />

composition <strong>of</strong> the waste and the release <strong>of</strong> CO2 within composting processes. This<br />

research, together with data sourced from technology suppliers, was used to model<br />

the degradation <strong>of</strong> carbon fractions within our model.<br />

Table 63-14 outlines the key assumptions within the model for stabilisation<br />

processes.<br />

Table 63-14: Assumptions for Stabilisation Process<br />

Parameter Parameter<br />

Assumption<br />

Assumption<br />

Residence time 10 weeks<br />

Electricity requirement 50 kWh / t input<br />

Diesel use by process 1 l / t input<br />

CH4 emissions from process 0.01 kg / t input<br />

N2O emissions from process 0.04 kg / t input<br />

Recovery rate for ferrous metals 80%<br />

Recovery rate for non ferrous metals 80%<br />

Recovery rate for plastics 70%<br />

Our assumptions for the landfill <strong>of</strong> pre-treated (stabilised) material have been<br />

previously discussed in Section 63.2.1.5.<br />

63.4.2 Air Quality Impacts<br />

To minimise emissions from the stabilisation process, air circulation and/or a<br />

controlled air supply system is usually installed. Bi<strong>of</strong>ilters are typically used to reduce<br />

emissions <strong>of</strong> NMVOC and other organic pollutants emanating from the stabilisation<br />

process itself. These involve the use <strong>of</strong> microorganisms to biologically degrade the<br />

pollutants.<br />

In the biological treatment step, the material is assumed to undergo an aerobic<br />

stabilisation. The emissions are derived from Hellweg et al, these being derived in<br />

turn from work by Wahlmann et al. 1250<br />

The principal air quality impacts are:<br />

Danish EPA; U. Sonesson (1996) Modelling <strong>of</strong> the Compost and Transport Process in the ORWARE<br />

Simulation Model, Report 214, Swedish University <strong>of</strong> Agricultural Sciences (SLU), <strong>Department</strong> <strong>of</strong><br />

Agricultural Engineering, Uppsala Sweden.<br />

1250 Stefanie Hellweg, Gabor Doka, Goran Finnvenden and Konrad Hungerbuhler (2003) Ecology:<br />

Which Technologies Perform Best?, in Christian Ludwig, Stefanie Hellweg and Samuel Stucki (eds)<br />

(2003) Municipal Solid <strong>Waste</strong> <strong>Management</strong>: Strategies and Technologies for Sustainable Solutions,<br />

London: Springer.<br />

1006<br />

29/09/09

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