Defra Release Research Results on the Characterisation of Residues from Industrial Processes and Waste Treatment
There are many drivers for managing wastes in a more sustainable way than consigning them to landfill. This has led to an expansion in the types of wastes that are being treated and the treatment processes employed, including: composting, anaerobic digestion, mechanical-biological treatment (MBT), gasification and stabilisation. However, very little information exists on the characteristics of these new treatment residues, making it difficult to predict release of metals, nutrients and greenhouse gases, following recycling to land or landfilling.
Defra’s Waste and Resources Evidence Programme commissioned a WRc-led consortium to undertake fundamental research into the composition, biodegradability and leachability of over 40 different waste streams. The key partners included the Open University, Cranfield University, Golder Associates (UK) Ltd and ECN (Energy Research Centre of the Netherlands). Project WR0110 “Characterisation of residues from industrial processes and waste treatment” aimed to fill some of the gaps in understanding the characteristics of treated wastes both from treatment of municipal solid waste (MSW) and residues from industrial processes.
The organic wastes tested included samples derived from mixed and source-segregated municipal solid waste (MSW), greenwastes and specific commercial wastes (e.g. chipped wood, cardboard packaging, turkey feathers, pizza waste and fish wastes), many of which had undergone treatment by composting, anaerobic digestion or autoclaving. The inorganic residues included filter cakes from physico-chemical treatment, bottom ash and air pollution control residues from MSW gasification, and output from a cement stabilization plant for hazardous wastes. A key initial activity for the WRc team was developing robust sampling and testing plans prior to collecting the samples, so that the huge analytical effort across six laboratories was not compromised.
Following analysis of the comprehensive datasets, a number of technical themes were explored:
- performance and correlation of selected biodegradability tests : short-term aerobic (DR4), long- term anaerobic (BM100) and enzymatic hydrolysis test (EHT);
- recycling stabilised and partially stabilised organic wastes to soil – metal content, nitrogen fertiliser value and leachability;
- landfilling of MBT outputs;
- air emissions from MBT plant;
- comparison of characteristics of residues from newer and well established treatment technologies (e.g. MSW gasification versus incineration).
The project has demonstrated the benefits of following a consistent sampling plan approach to the sampling and testing of a wide range of wastes. A valuable new public domain dataset has been generated on the composition, leachability and biodegradability of waste treatment residues, increasing the evidence base for policy makers and waste management specialists. The final report and full characterisation datasets are available from Defra’s web-site. Nick Blakey, Head of the Waste and Resources Evidence Branch at Defra commented "We are pleased with the project which will provide a useful resource and data for future modelling. It was a complex piece of work, with a large team to organise, and we valued WRc's good project planning and management.
WRc have provided the consultative material required in a format that makes the information accessible for those that needed to understand it and we like the knowledge brokering approach in helping to communicate the policy implications."
For more information about this project or WRc’s in house waste characterisation services please contact Kathy Lewin or
Jane Turrell.