Legislation Details for Anaerobic Digestion

Introduction

Anaerobic Digestion needs sources that are high in nitrogen content, contain suitable bacteria, and moreover that are inexpensive and readily available. Most often this means using faeces of some sort as part of the process. In this case the two sources are cattle slurry and wet vegetable waste.

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Applicable and Non-applicable Legislation

Use of waste in this instance would be a good deal simpler than the septic system Barony College currently utilises – there is no human waste involved. Likewise there is no animal waste proposed for use, so the Animal By-Products Regulations (Scotland) do not apply; Municipal Solid Waste (MSW) is not to be used so neither does the EU Landfill Directive.

Concerns arise due to the possible spread of pathogens, particularly cross-contamination from different sources; this is avoided by the pasteurisation of digestate at >70°C for more than one hour before any further composting or direct use.

It must be ensured that the system itself is sealed from the atmosphere, both to avoid excessive odour and importantly to avoid the airborne spread of pathogens before pasteurisation. This is covered under the European Integrated Pollution Prevention and Control Directive. The tanks should also be sealed and surrounded by clay or concrete to prevent seepage to ground water.

Vehicles using the facility must have a separate area for washing – wheels, tyres etc. – before leaving the facility. While going to and from the facility consideration should be given to routing vehicles away from sensitive areas such as schools. Personal hygiene arrangements should also be considered.

The EU Nitrate Directive (applicable to digestate) states that no more than 250kg per hectare per year of nitrates may be applied to land in the UK. This is primarily to protect water courses from algal pollution.

General legislation is also applicable for planning consent etc. Any proposals for a waste treatment plant must go out to public consultation under the Public Participation Directive.

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Further Information

1. The European Anaerobic Digestion Network
2. Europa
3. Scottish Executive
4. SEPA

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