Guidance

Treating municipal waste by aerobic digestion: RPS 257

Published 18 July 2022

Applies to England

This regulatory position statement (RPS) does not change your legal requirement to have an environmental permit when you aerobically digest residual mixed municipal waste at the place the waste was produced.

However, the Environment Agency will not normally take enforcement action against you if you do not comply with this legal requirement provided that:

• your activity meets the description set out in this RPS

• you comply with the conditions set out in this RPS

In addition your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:

• cause a risk to water, air, soil, plants or animals

• cause a nuisance through noise or odours

• adversely affect the countryside or places of special interest

Activity this RPS applies to

This RPS applies to the aerobic digestion of residual mixed municipal waste (waste code 20 03 01), at the place where the waste was produced. For example, shopping centres, hospitals, universities, restaurants, cafes and schools. 

Conditions you must comply with

You must :

• only treat the residual mixed municipal waste after you have removed any dry recyclable non-biodegradable waste streams and managed these in line with the waste hierarchy
• only treat the residual mixed municipal waste after you have removed most of the food waste and managed this in line with the food and drink waste hierarchy
• only treat residual mixed municipal waste (waste code 20 03 01) by shredding, followed by aerobic digestion
• only treat a maximum of 10 tonnes of residual mixed municipal waste per day
• store and treat the waste in a secure place – one where you have taken all reasonable precautions to prevent waste escaping and where the public cannot access it
• store the waste before and after treatment in containers that are fully enclosed and leak-proof to prevent and minimise odour, stop liquids escaping and prevent access by vermin and pests
• treat odorous emissions to air using appropriate abatement techniques, for example carbon filters
• operate and maintain the aerobic digestion plant and replace carbon filters, following the manufacturer’s instructions
• keep records for 2 years from the date of the last use of the RPS to show that you have complied with this RPS and make these records available to the Environment Agency on request

You must notify the Environment Agency by email at wastetreatment@environment-agency.gov.uk before you use this RPS. In your email include:

• the words ‘RPS 257’ in the subject line
• your name, company name and contact details
• the address of the site where the RPS will be used

You must not:

• store waste for more than 7 days before treating it
• discharge any effluent produced to drainage systems which discharge to surface water or groundwater

Things to note

Residual mixed municipal waste is what is left when as much as possible of the food waste and dry recyclables, such as paper, cardboard, plastic and metal, have been removed. Residual mixed municipal wastes are the remaining fractions which are contaminated with left-over food which makes them difficult to recycle. Aerobic digestion treats these biodegradable contaminants.

This RPS relates to an activity that the Environment Agency considers is potentially suitable to be an exemption under the Environmental Permitting (England and Wales) Regulations 2016.

If you generate an effluent, you must get authorisation from the sewerage undertaker before discharging any effluent from the process to foul sewer. 

When you must check back

The Environment Agency will review this RPS by 30 January 2026. 

The Environment Agency can withdraw or amend this regulatory position before it expires if they consider it necessary. This includes where the activity that this RPS relates to has not changed.

You will need to check back from time to time, including at and before the review date, to see if this RPS still applies.

You can subscribe to email updates about this RPS. These will tell you if the RPS has changed and when it has been withdrawn.

This RPS remains in force until it is removed from GOV.UK or is otherwise identified as having been withdrawn.

If you cannot comply with this RPS

If you operate under this RPS but can no longer comply with it, you must:

• stop the activity to which this RPS relates
• tell the Environment Agency immediately by emailing wastetreatment@environment-agency.gov.uk and put ‘RPS 257’ in the subject

Contact the Environment Agency

If you have any questions about this RPS email enquiries@environment-agency.gov.uk and put ‘RPS 257’ in the subject.