Anaerobic Digestion (AD)
A sustainable energy production
and waste management solution for your business
Robert Crow
30 September 2014
Summary
• Services offered to SMEs by Abertay University• Legislative drivers• Economic drivers• The science of AD• Feedstocks & pre- treatment• AD process outputs – Energy & Digestate• Factors to consider when installing AD systems
SBP – Abertay AD Expertise
• Biochemical Methane Potential (BMP) assays
• Feedstock analysis and pre-treatment
• Reactor and pilot scale trials• Process development, design and
optimisation• Bespoke training packages offered
developed for operators and businesses new to the sector
Legislative drivers: Organic waste
EU legislation Scottish legislation
The Waste (Scotland) Regulations 2012
• All businesses in Scotland that produce over 50kg of food waste per week require this to be separated and uplifted to a permitted treatment facility
• A ban on using on using macerators to discharge food waste into the public sewer is coming into force on the 1st of January 2016.
• An energy opportunity exists since the biogas created from AD can be combusted within a CHP to generate a source of power and heat.
Economic Drivers
• Landfill tax currently £80 per tonne of active waste
• Add on the gate fee!!• Price of raw
materials increasing – waste recovery and adding value is becoming necessary
Anaerobic Digestion – The science
Source – Renewable Energy Concepts 2013
Feedstocks
Pre-Treatment of Feedstocks
• Reduction of feedstock particle size
• Feedstock blending • Feedstock containing
grit or sand• Removal of
packaging /pasteurisation
Source – SLR consulting 2009
Feedstock assessment & process monitoring
• Moisture Content (%)• Total Solids (%) / Volatile Solids (%)• pH• Volatile Fatty Acids (VFA) (mg/L HOAc)
• Methane Yield (ml CH4 /g VS added)
• C:N Ratio
Animal By-Products Enforcement (Scotland) Regulations 2011:
Anaerobic Digestion• Implemented as a result of
the 2001 Foot & Mouth disease outbreak and BSE crisis– Category 1 (cannot be
treated by AD)– Category 2 (steam pre-
treated unless manure or milk)
– Category 3 (pasteurised before digestion)
Energy Utilisation
Source SLR Consulting (2008)
End markets for AD digestate?• Horticulture • Agriculture • Brown field
site restoration
• Landfill daily cover
INCREASING VALUE
PROCESSING REQUIREMENT
http://www.wrap.org.uk/content/digestate-compost-agriculture
PAS 110 Standard
• Specification that allows digestate to be declassified as a waste– Physical tests– Chemical tests– Microbiological tests– Growth trials– Stability Tests
Key Issues developing AD systems
• Initial feedstock assessment & feedstock supply• Process monitoring & measurement essential• Knowledge exchange between AD technology
providers and operations staff• Engage SEPA at a early stage• Consult your local planning officer• End use of the biogas, heat and digestate
should be considered
Any questions?
