challenges & opportunities of pre-treatment for ad...
TRANSCRIPT
Challenges & Opportunities of pre -treatment for AD Plants
Mike BullardManaging Director, UTS Biogas Ltd
Contents
• Introduction to UTS/Anaergia• “pre-treatment” agricultural systems
In contrast to
• “pre-treatment” SSO waste systems• Conclusions
Biogas plant May
Farm, Ely, CambsBiogas plant Dagenham, London
Case-studies in the presentation
Manure/grass Biogas
plant, Yorkshire
About Anaergia / UTS Biogas
4
• Global technology leader in the recovery of value from organic waste
streams
• Proven portfolio of proprietary technological solutions around
anaerobic digestion core
• Flexible project delivery options, including process turnkey supply,
DBOO (including financing)
• Over 20 years of design and operating experience
• Core technologies used in over 1,600 digester plants with over 355MW
of capacity from biogas
• UTS Biogas Ltd is the sole delivery agent for all Anaergia products in
the UK and Ireland (UK based technical and project management)
• In the UK: 9 plants operational, 4 larger facilities in-build.
• Turnkey design construct commission services; pre-treatment, biogas
production and utilisation; digestate management. CHP and BtG. EPC
or technology supply.
Anaergia’s Technology Platform Built On In -house Manufacturing, R&D and Exclusive Partnerships
Organics Pre-treatment Core Technology Post Treatment
Organics Extrusion
DB Technologies
Recyclable Recovery
DB Technologies
Solids Separation
Anaergia / UTS
Hydraulic Mixing
Anaergia / UTS
Service Box
Anaergia / UTS
Materials Handling
Anaergia / UTS
Residuals Drying
Therma-Flite
(Exclusive Partner)
Membranes
Fibracast
(Subsidiary)
Gasification
KIV
(Exclusive Partner)
Biogas Upgrading
Greenlane
(Partner)
Anaerobic Digesters
Anaergia / UTS
Pre-treatment; what’s the problem?
Key issues
• Heterogeneity – good pre-treatment produces homogeneity in the feed material
• Contamination – good pre-treatment removes contaminants effectively
• Accessing the organics – good pre-treatment capture a high proportion of organics for AD
• Recyclates recovery – good-pre-treatment enhances recyclate value
• Keeping the organics clean – boosts gas yields• Achieving PAS110 – all of the above needed to
achieve PAS110 and thus meet end of waste criteria
May Farm
Primary Fermenters
Secondary Fermenters
Digestate Storage Tank
CHP Area
Pasteurisers &
Separator
Incoming
Solid Feed
Weighbridg
e
Conditioning
Feed
hopper
Output-Fibre
Separated Solid
Digestate
Separator Digestate
Storage Tank
Buffer
Tank
Batch
pasteurisatio
n
Maceration
Output
Liquid
digestate
Primary
Fermenter
Secondary
Fermenter
CHP
Output
Electricity
Output
Heat
Desulphurisatio
n
Conditioning
May Farm process flow
Grass/ manure Biogas plant
Incoming
Solid
Weighbridge
Conditioning
Feed
hopper
Output-Fibre
Separated Solid
Digestate
Separator Digestate
Storage Tank
Output
Liquid
digestate
Fermenter
CHP
Output
Electricity
Output
Heat
Desulphurisation
Incoming
Liquid
Receptio
n tank
Stone Trap
Grass/ manure Biogas plant
Static pre -treatment solution
Mobile pre-treatment solution
Dagenham
Composting building
Incoming
Waste
Weighbridg
e
Reception building
Biowaste
Preparation
equipment
Output-Fibre Hall
Separated Solid
Digestate
Separator Digestate
Storage Tank
Buffer
Tank
Batch
pasteurisatio
n
Maceration
Output
Liquid
digestate
Receptio
n tank
Primary
Fermenter
Secondary
Fermenter
CHP
Output
Electricity
Output
Heat
Desulphurisatio
n
SSO treatment- Key process design parameters -
Process design parameter Unit Value
Solid concentration organic fraction % of wet 25 – 35
Volatile solids organic fraction % of dry 85 – 95
Solid concentration input digester % of wet 25 - 30
Solid concentration output digester % of wet 10 - 15
Organic loading digester kg VS/(m3*d) 6.5 – 8
Hydraulic retention time (HRT) digester Days 40-60
Specific biogas production Nm3/t VS 680 – 750
Specific biogas production Nm3/t wet 130 – 150
Contamination levels % (w/w) 3-25%
MSW / SSO treatment
- Low contamination -
SSO upfront processing system: Hammer Mill
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• Hammers disintegrate contaminants
(glass, plastic)
• Organic fraction for AD is
‘contaminted‘ with glass, plastic
• The more the SSO contamination level
as more water is required to process
the SSO
• Challenged by contamination > 10% -
Grit and plastic separation systems are
required if highly contaminated SSO is
treated
• More process water = greater digester
size = greater costs
• Biobags are an issue
• Not suitable for processing biowaste
with high green waste content
• Heavy parasitic power consumption
• Reject stream needs to be pressed to
reduce moisture content
• Difficulty dealing with heterogenous
wastes
Other SSO: alternative upfront processing systems
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Impacts of poor pre -treatment
• Poor removal of contraries leading to build up of silts, sediments, plastics floating layers.
• Loss of digester capacity – silting and additional water addition
• Potential toxicity• Failure to achieve PAS110 (plastics)• Extra costs of post-process digestate screening• Additional mixing causing higher electricity consumption• Greater organics carry-over in residual waste stream; loss of
biogas yield and potential recycling target issues• Blockages• Additional pump wear and tear – increased opex• Heterogeneity – loss of gas yield
Conclusions
• Hammer-mill and turbo-separator systems available in the market place:– Require significant amounts of process water and
therefore have cost impacts on remainder of plant design
– Do not cope with high levels of impurities– Do not recover high proportions of organics– Leave a dirty residual stream– Have high opex costs– Do not give a clean organics stream
• The waste industry needs something better!
