3. Bespoke wastes suitable for biological treatment

The source segregated biodegradable wastes the Environment Agency considers to be generically suitable for biological treatment.

Most organic waste streams of biological origin sent for biological treatment are well understood. The source segregated biodegradable wastes the Environment Agency considers to be generically suitable for biological treatment are included in the:

1. The Environment Agency recognises the potential to use biological processes to treat other ‘non-standard’ or ‘bespoke’ wastes. However, any waste sent for biological treatment must be capable of being treated by the process. Dilution is not considered a suitable waste treatment.

2. Biological processes can degrade complex synthetic organic substances. The products resulting from these biological degradation processes may pose a significant threat to human health and the environment. You must therefore fully characterise and assess all bespoke wastes before introducing them into a biological treatment process.

3. If you accept a bespoke waste type your site permit must have the relevant list of waste (LoW) code and description as set out in the technical guidance (WM3). Typically, this applies to waste from a single producer. If you accept similar waste from a different producer it will require its own pre-acceptance assessment and you may need to apply for a permit variation to make sure these pre-acceptance processes are part of your operational techniques.

Additional guidance on characterising and assessing waste is available in WM3 and the waste pre-acceptance and acceptance section of this guidance. Inhibitory ranges are provided in section 13 Bespoke waste assessment as guidance for aerobic and anaerobic processes. These are aimed at helping operators fully assess whether treatment will be effective, and any requirement for pre-treatment and additional process control measures. Operators may need to test the resulting outputs to make sure the material has been fully treated.

3.1 Animal by-products

Biological treatment facilities may need to comply with The Animal By-Products (Enforcement) (England) Regulations 2013 (ABPR) to accept and treat animal by-products. This is regulated by the Animal and Plant Health Agency (APHA). More information is available from the APHA on the definition and categorisation of animal by-products. Biological, organic treatment facilities can be authorised to accept category 3 animal by-products.

3.2 Energy crops and by-products (residues)

1. AD plants, where the only feedstock is grown energy crops such as maize or by-product from food waste productions (some crop residues), do not currently need an environmental permit or exemption for the digestion process.

2. Operators will need a permit for any combustion unit (engine, boiler or generator). Time lines for compliance with emission limits may vary for combustion units. For more information please refer to guidance on medium combustion plant and specified generators.

3. AD plants taking mixed feedstocks (energy crops, slurry, manure and waste) require an environmental permit for the digestion process and any associated combustion unit or specified generator.

3.3 Wash down waters, liquor and leachate

1. Materials produced incidentally to a process, for example clean down or wash waters, leachates and liquors from feedstock storage, are waste. For example, where water has:

  • permeated through a material
  • resulted from that material being stored (such as silage liquor)
  • resulted from composting

2. Transfer and disposal of waste must comply with the duty of care code of practice under section 34 (7) of the Environmental Protection Act 1990.