anaerobic digestion & markets for digestates david tompkins agriculture sector specialist
TRANSCRIPT
Anaerobic digestion & markets for digestates
David TompkinsAgriculture Sector Specialist
WRAP’s vision is a world without waste, where resources are used sustainably.
We help businesses, individuals and communities reap the benefits of reducing waste, developing sustainable products and using resources in an efficient way.
About WRAP
Focus on food waste
Reduction and re-use of food and drink wastes 16Mt of post-farm gate food and drink waste 5.3 Mt of avoidable household food waste
– Representing over 20 million tonnes of CO2e– 3% of total UK GHG emissions– 6% of total UK water footprint– 1 in 4 cars on the road in the UK
Ideally this waste would be prevented– Where this is not possible, it should be
recycled– Composting offers one solution– AD offers another – with the advantage of
renewable energy
Main WRAP driver
Anaerobic digestion (AD)
Anaerobic digestion (AD)
Farm-fed
Food-waste-fed
Industrial processes http://biogas-info.co.uk/maps/index2.htm
AD in the UK
107 operational facilities 44 farm-fed (manures, slurries,
crops) 47 food-waste-fed (households) 16 industry-fed (distilleries,
dairies) Total capacity ~5Mtpa ~ 230 more plants in planning
Classification by input: Manures and purpose-grown crops Waste-derived:
– Source-segregated– Mixed
Biosolids and co-digestates
AD can be: Wet (<15% DM) or dry Mesophilic (35 - 40°C) or
thermophilic (55 - 60°C)http://www.defra.gov.uk/publications/files/anaerobic-digestion-strat-action-plan.pdf
Types of digestate
Most UK digestates are low dry matter (<10%)
Can be separated– Fibre– Liquor
Different fractions have different physical and chemical characteristics– Different potential uses
Digestate is not just digestate…
Digestate regulations
WRAP focusses on digestates derived from source-segregated wastes, including:– Food processing residues– Kitchen waste– Crop processing residues
As soon as a waste is mixed with non-waste, the whole mix becomes a waste
BUT… there is a way out of this
[Digestates derived from manures and purpose-grown crops not normally regulated]
To transform ‘waste’ digestates into ‘products’ Two parts:
– Anaerobic Digestate Quality Protocol– Approved specification (PAS110)
If an operator complies with both and is independently certified to both, then the biofertiliser is no longer a waste and can be used as a product
BUT, ADQP lists allowable markets
www.biofertiliser.org.uk
Digestate regulations
PAS110 specification includes limits on: E. coli and Salmonella PTEs (Cd, Cr, Cu, Hg, Ni, Pb, Zn) Digestate stability Physical contaminants
PAS110 specification requires tests for: pH Total nutrients & ammonium-N Dry matter
Digestate regulations
WRAP’s market development work
>99% digestate is used in agriculture– Replicated field experiments across the UK– www.wrap.org.uk/dc-agri– Biofertiliser Matrix
Other uses– Brownfield restoration and regeneration
(particularly energy crops)– Soil manufacture – Turf establishment– Sports and amenity turf maintenance
As an ingredient in growing media As a liquid feed for containerised strawberry
production In soil-less hydroponic trials
Key questions:– Can digestate be used in these
applications?– What are the constraints?– Can these be overcome?– Are there business benefits?– Should the ADQP be changed?
Horticulture pre-feasibility trials
