Commission Regulation (EC) 208/2006 specifies the conditions for composting of Category 3 animal by-product (ABP) materials. This comprises of a temperature of 70°C for 1 hour with a minimum particle size of 12 mm. Defra may also authorise the use of other process parameters provided the applicant demonstrates that such processes ensure minimisation of the biological risks. That evidence should include a validation demonstrating that the process achieves the following overall risk reduction for thermal processes by;
• Reduction of 5 log10 of Enterococcus faecalis or Salmonella senftenberg (775W, H2S negative)
• Reduction of infectivity titre of thermo resistant viruses such as parvovirus by at least 3 log10, whenever they are identified as a relevant hazard.
While reduction of Enterococcus faecalis or Salmonella Senftenberg is straightforward and prescriptive, there is a need to identify those thermo-resistant viruses which constitute a relevant hazard in Category 3 ABPs used as incoming materials in biogas and composting plants. The objective of the work proposed here is to identify those thermo-resistant viruses that constitute a relevant hazard in Category 3 ABPs (for example, meat, raw milk, catering waste and blood) used as incoming materials in biogas and composting plants. This includes a consideration of parvoviruses, caliciviruses, and circoviruses. Where possible, it is proposed to construct thermostability plots for 3-log10 reductions of those viruses to enable comparison with bovine parvovirus and Salmonella Senftenberg (775W, H2S negative).
An initial list will be compiled of those viruses of importance to animal and public health as listed by the OIE, HPA and Defra, together with any additional viruses identified by experts within VLA Virology. Those viruses likely to be present in Category 3 ABPs used as incoming materials in biogas and composting plants, i.e. those that are transmitted by products of animal origin, and those of higher thermo-resistance will be identified and further considered in the analysis. This final list will be composed of up to a maximum of 20 prioritised viruses, and may also include infectious pancreatic necrosis virus (IPNV) as an example of a fish virus.
A literature review will be carried out for the thermostabilities of the identified viruses together with the two standards: bovine parvovirus and Salmonella Senftenberg (775W, H2S negative). Where information is available, those factors (or conditions) within composting and biogas production which could potentially enhance the thermostability of a group of viruses would be listed. From the information obtained, thermostability plots, where possible, will be produced comparing the times taken reductions in infectivity titre at different temperatures with bovine parvovirus and Salmonella Senftenberg (775W, H2S negative). A ranking will be produced of the thermostabilites of those viruses compared to the bovine parvovirus and Salmonella Senftenberg (775W, H2S negative) markers.
A presentation to Defra and other stakeholders will be made during month 5 of the project with the preliminary results from the analysis. The methodology and findings of the work will be drafted into a final technical report at the end of Month 5.