Regulation 142/2011 and the biogas plant: pasteurisation at 70°C/60 min, 12 mm and the requirements

Commission Regulation (EU) No 142/2011 sets in annex V the standard hygienisation parameters in a biogas plant: particles up to 12 mm, minimum 70°C throughout the mass for at least 60 minutes without interruption. This is the basic condition for category 3 material and for category 2 material introduced without prior sterilisation. Below is a summary of what exactly is required, what the exceptions are and how digestate quality is assessed.

Standard parameters

The same values apply to composting in a reactor: 12 mm, 70°C and 60 minutes.

When pasteurisation is not required

Annex V provides that a hygienisation unit is not needed for, among others:

• category 2 material processed by method 1 (pressure sterilisation: particles up to 50 mm, above 133°C, minimum 3 bar, 20 minutes);
• category 3 material processed by methods 1–5 or 7;
• material already hygienised in another approved plant;
• manure and other materials that may go onto land without processing (Article 13(f) of Regulation 1069/2009), if the authority sees no serious risk;
• by-products subjected to alkaline hydrolysis;
• certain dairy products (milk, colostrum) with the authority's consent.

For installations that receive only such materials, the requirement for a hygienisation unit falls away, which simplifies the investment. Everything depends, however, on the content of the plant's approval.

Alternative parameters

The authority may approve parameters other than the standard ones if the applicant has validated them. The validation must demonstrate:

• a reduction of at least 5 log₁₀ for Enterococcus faecalis or Salmonella Senftenberg (775W, H₂S negative) in thermal and chemical processes;
• a reduction of at least 3 log₁₀ for resistant viruses (e.g. parvovirus), where this is relevant;
• in chemical processes — a reduction of at least 99.9% (3 log₁₀) of resistant parasites, e.g. roundworm eggs.

For kitchen waste and certain mixtures (with manure, dairy products or eggs), separate alternative requirements may be approved, as well as requirements for plants in which the only animal material is the listed raw materials. In practice validation requires testing and can be costly, so the standard parameters are more convenient.

Standards for digestate and compost

After processing, digestate and compost are sampled for testing:

They are sampled during or immediately after processing (indicator bacteria) and during or on removal from storage (Salmonella). If a batch does not meet the standards, it is reprocessed or composted, and in the case of Salmonella — the authority's instructions are followed. The authority may permit sampling after pasteurisation but before mixing with non-animal material.

Hygiene requirements around the installation

Chapter II of annex V requires, among other things, processing of material without undue delay after receipt and proper storage, washing and disinfection of vehicles in a designated place, documented pest control (birds, rodents, insects), documented cleaning and regular inspections, calibration of equipment and handling of digestate in a way that excludes recontamination.

Practical design tips

• Shredding before hygienisation. Particles of up to 12 mm are usually achieved in a shredder or macerator; hard elements (bones, packaging) must be removed beforehand.
• Measurement throughout the mass. The 70°C requirement applies to the whole mass, not only the walls of the tank — the probe and mixing must confirm this.
• Continuous time. The 60 minutes are counted without interruption; interrupting heating means repeating the cycle for the given batch.
• Batch versus continuous system. In a continuous system it must be guaranteed that every particle actually spends the minimum time in the 70°C zone, and not merely the average residence time.
• Heat recovery. Heat from the exchanger after hygienisation often heats the feed at the inlet, which reduces the consumption of process heat.

Common mistakes in practice

1. Designing without distinguishing between categories 2 and 3, and then "adjusting" the application.
2. No control system that blocks the flow in the event of underheating.
3. Sampling digestate at a point where the material is already mixed with non-animal components, without the authority's consent.
4. Testing too infrequently in the first months, when the process is not yet stabilised.

How it looks for different substrates

The summary is indicative: ultimately what counts is the content of the approval of the given plant.

What to do first

1. Decide which substrates are cat. 2 and which are cat. 3.
2. Check whether any of them benefits from an exception to pasteurisation.
3. Plan the design of the hygienisation module (buffer tank, shredder, temperature measurement).
4. Establish the laboratory and the schedule of digestate tests.
5. Agree the scope with the county veterinary officer at the approval application stage.

This text is for information purposes only and does not constitute legal advice; before an investment or formal decision, check the current wording of the provisions and consult a lawyer or the competent authority.