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?