A UK specification for renewable fertilizer has been updated. The change means that more operators of anaerobic digestion (AD) plants will be able to use or trade their digestate as certified biofertilizer.
The revised digestate stability criteria in the PAS 110 specification reflect digestate's equivalence to organic materials commonly spread on land such as pig slurry. Previously it was deemed equivalent to cow slurry. It can also now be marketed as a biofertilizer under the Biofertiliser Certification Scheme from Renewable Energy Assurance Ltd.
At the same time, environmental protections have been strengthened. The limits on contaminants such as plastics have been tightened in order to raise quality and safety standards.
Digestate is produced at AD food-waste-to-energy facilities. Provided it meets the PAS 110 quality standards it can be used as biofertilizer for agricultural purposes.
There are several environmental benefits associated with the use of biofertilizer. It helps to restore important nutrients, water and organic matter to the soil, while reducing the need for mineral fertilizer. It also helps to keep food waste out of landfill, where it releases methane into the atmosphere as it decays.
At present there are 15 AD plants across the UK that produce certified biofertilizer.
The updated PAS 110 specification is expected to lead to an increase in the volume and quality of certified biofertilizer.