Anaerobic Digestion

You may be able to treat your biodegradable waste using anaerobic digestion. This uses natural bacteria to convert waste into:

  • biogas, which can be used to generate electricity and/or heat
  • liquid, which can be used as a fertiliser
  • solid, which can be used a soil improver.

Increasingly AD is being used to make the most of our waste by turning it into renewable energy.

What you must do

Operating an anaerobic digester

Before you operate an anaerobic digester to treat food waste you must have a pollution prevention and control (PPC) permit, waste management licence or registered exemption.

You may need to register a paragraph 13 exemption for composting and storing biodegradable waste in Northern Ireland. If you have an exemption, you must comply with the exemption conditions.

DAERA: Paragraph 13 Composting and storage of biodegradable waste

If your waste includes animal by-products you must have approval for your anaerobic digester from Animal Health in Scotland or the Divisional Veterinary Offices (DVO) in Northern Ireland.

Animal by-products and food waste

Burning biogas as fuel

If you burn biogas you must have a:

  • waste management licence or exemption for an appliance with a rated thermal input of less than 1MW
  • a pollution prevention and control permit for new appliances with a rated thermal input of 1 MW or more. Plants with a thermal input rating of between 1 MW and 20 MW that were put into operation before 20 December 2018 will need a PPC permit by 1 January 2024 or 1 January 2029 depending on the size of the plant. 

Pollution prevention and control permits

Waste management licences

You may be able to register an exemption from the need to hold a permit or licence in Scotland, if the inputs are less than 100 tonnes per day, and are only agricultural wastes and distillery wastes.

If you operate under a registered exemption you must still ensure that your activity does not:

  • endanger human health
  • cause pollution to water, air or soil
  • cause a risk to plants or animals
  • cause a nuisance in terms of noise or odour
  • adversely affect the countryside or places of special interest.

SEPA: Waste management licensing exemptions (Paragraph 51 Exemption)

SEPA has produced guidance that explains how they will regulate the use and handling of digestate outputs from the AD process.

SEPA: Regulation of Outputs from Anaerobic Digestion Processes

Further information on the production of biogas, and case studies, can be found on the Anaerobic Digestion Portal.

Further Information

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