Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Search List

Analysis of biodegradability of residual waste based on subtraction of diverted materials - WA0214

Work commissioned by DEFRA to establish the biodegradability and composition of municipal waste being sent to landfill (WR1003) seems to suggest the currently assumed figure of 68% biodegradability of MSW being sent to landfill should be updated. The 68% figure first arose from a calculation attempting to quantify household waste by combining kerbside, civic amenity site and some other waste data sources (Parfitt 2002). Since then, DEFRA’s working assumption has been that this figure, derived for combined household waste, can also be applied to landfilled MSW – in effect that the biodegradability of total household waste, residual municipal waste and MSW sent to landfill are all equal, at 68%. At the time, given the lower state of development of recycling and food/garden waste collection, this may have been a reasonable assumption.

This assumption was called into question by WR1003 Biodegradability of municipal solid waste, which suggests that mixed municipal waste sent to landfill (defined by that study as EWC codes 20.03.01 and 19.12.12, of local authority or commercial origin) has a significantly lower biodegradability (51% for all landfill MSW and 59.5% for untreated household waste to landfill under EWC 20.03.01). DEFRA projects to model national waste composition based on existing compositional studies (WR0119 and EV0801) support the case for the biodegradability figure for residual waste being considerably lower.

The aim of this proposal is to provide additional evidence of what proportion of household waste sent to landfill in 2010/11 was biodegradable, by modelling the effects of removing accounted for diverted materials from a pool of household waste (with an assumed biodegradability of 68% for the combined waste) on the residual material. This will enable an assessment of whether the 68% combined household BMW figure from the 2002 research and the lower landfill figures from WR0119, WR1003 and EV0801 are reconcilable. To maximise comparability, the untreated-household (rather than total landfill MSW) figure from WR1003 will be used - this is 59.5%.

A revised version of the (68%) combined household biodegradability figure will also be calculated using contemporary compositional studies and information from Waste Data Flow, and a comparable figure for municipal solid waste (including sources such as local authority trade waste collections, street sweepings etc).

This study assumes that material sent by local authorities to incineration has a similar composition and biodegradability as material sent to landfill, and so does not propose to distinguish between residual waste and waste sent to landfill. This assumption is necessary due to a lack of robust information on the composition of EfW inputs and outputs.
The objective of this project is to assess the compatibility of the Parfitt (2002) BMW in combined household waste figure of 68% with the untreated household BMW in landfill figure of 59.5% from WR1003. This will be done by subtracting the dry recycling and organic diversion accounted for in Waste Data Flow from a pool of combined household waste with an assumed biodegradability of 68%, and evaluating the projected biodegradability of the remaining material. In addition, new figures for combined municipal and household waste will be constructed based on 2010 Waste Data Flow data and data from waste composition studies.
Project Documents
• FRP - Final Report : WA0214 FINAL REPORT   (510k)
• ANX - Annex : WA0214 Data appendix   (46k)
Time-Scale and Cost
From: 2014

To: 2014

Cost: £3,150
Contractor / Funded Organisations
Resource Futures Ltd
Fields of Study
Environmental Protection - Agriculture