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Reducing Landfill: A Landfill Allowance Scheme Consultation

ANNEX B: DETAILS OF THE MASS BALANCE SYSTEM

Under this system, municipal waste arriving at landfill sites is not subject to an intensive sampling programme and therefore the composition of waste landfilled is probably unknown. The quantity of BMW landfilled can be calculated from the following equation:

BMW%= the proportion of municipal waste (MW) that is biodegradable
MBT= Mechanical Biological Treatment

To calculate the quantity of BMW landfilled, information for each of the boxes on the right hand side of the equation is needed. The information required is:

1. The quantities of all the waste streams sent to each destination. These will include separate biodegradable fractions such as paper and green waste taken for recycling, composting or anaerobic digestion; separate non-biodegradable fractions such as steel, glass and plastic and mixed waste destined for mechanical-biological treatment (MBT) incineration, or other treatment;

2. The average biodegradable content of separated waste fractions such as textiles, which are not regarded as 100% biodegradable;

3. The biodegradable content of the residues/outputs going to landfill from treatment processes such as MBT;

4. The quantity of MW produced and the biodegradable fraction of the municipal waste for each authority.

The sources of this information are as follows:

1. the quantities of waste would be taken from weighbridge tickets/receipts provided by local authorities;

2. the biodegradable proportion for each fraction of waste and for MW as a whole would be taken as 63% initially, although this might be revised;

3. the biodegradable content of the residues/outputs going to landfill from treatment processes such as MBT would be calculated from standard factors;

4. the quantity of MW produced would be calculated from the addition of MW tonnage to all the outlets. Consideration is being given to making allowance for home composting, if a reliable estimate can be made.

This monitoring scheme could require:

• an ongoing programme of research into municipal waste composition to determine the composition of waste in each local authority;
• some changes to the Duty of Care to require certain details to be passed to the disposer or recoverer and SEPA;
• changes to the exemptions for certain recycling and recovery facilities requiring details of wastes received to be passed to SEPA;
• an independent assessment of the performance of different waste treatment processes in achieving a reduction in biodegradable content of MW; and,
• a power to set the biodegradable waste diversion for different technologies.

TREATED BIODEGRADABLE WASTE

When waste is treated, that treatment may be biological, physical or thermal. (Chemical treatment is obviously possible but there are no known processes using chemical conversion). By reducing the biodegradable content of waste, treatment should reduce the amount of BMW which is sent to landfill and therefore contribute towards meeting the objective of Article 5 of the Landfill Directive.

An assessment of the biodegradable content in the residues sent to landfill will depend on several factors, including:

• the type of process;
• the way it is operated;
• the residence time before landfill;
• the composition of the waste input.

In order to establish appropriate factors for reduction in BMW, the Environment Agencies will be carrying out work to:

• review the available tests for biodegradability;
• recommend those that are most suitable;
• establish any relationship between the recommended or other tests;
• produce a means of modelling the outputs of different processes according to the waste input, treatment time etc.

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