Walpole Anaerobic Digestion Plant

Overview

• Monsal technology• 30,000 tonne annual capacity• Potential further 15,000 tonnes• C 1mw electricity export per annum• C .3mw electricity parasitic loading• ABPR Compliant• PAS110 output• Heat use / gas injection

30,000 Biowaste plant–Short Mass Balance

Pre-Processing AD plant Biogas CHP

Waste 30,000 tpa

Power 1.3 MWe

Compost 13,000 tpa

Makeup Water

Biogas production500 m3/h

Waste Water

anaerobic digestion development

Food Waste Collection – Source Segregated

• Dry solids 23% - 28%• Few Contaminants

Waste Reception Processing

• Heavy duty shredder

•Twin shaft design/intelligent

•< 50mm initially

• Interim surge hopper (bunker)

• Localised odour containment/control

Waste dissolvers – pulping of biowaste

• Digester Feed Preparation

• Slurry Organics

• Reduce Particle Size

• Leave Plastics Intact

Waste dissolver – cleaning up and de-packaging

• Light fraction removal

• Large sump capacity

• Heavy fraction removal

• Compaction area

• Effective Separation

Buffer Tank / Hydrolysis Stage

• 6 Days retention

• Stage 1 of Digestion

• Pump mixed

• Dry solids 8% - 12%

• Connected to gas head space to contain odour

Pasteurisation Stage

• 3 Tank system

• 70C for >1hour

• Hot water from CHP

• Each batch logged for Animal Health

Digester

• Mesophilic Digester

• 2nd Stage (Methane)

• Energy Efficient Mixing

• Biogas for Heat and Power

advanced digestion technology

Dewatering / Product

• 25% dry solids

• Cake recycled to land

• ABPR Complete

• PAS 110

advanced digestion technology

advanced digestion technology

Odour Containment and Management

• Localised containment

• Common gas spaces

• 2-3 air changes/hour

• Positively displaced biofilter

Treatment of liquors (and recycling)

• Fully integrated system

• SBR biological treatment

• Provides buffering, treatmentand make up water

• Effluent can be discharged to sewer

Gas / CHP

Two CHP engines – 1MW and .5MW

Heat use - within the process for sterilisationother options

glasshousesleachate treatment works

Preferred option is Gas Injection

Heat use

Gas Injection

Gas injection –100 kw gas = 40kw electricity export100 kw gas = 90 kw gas export

Pressure swing absorber – scrubs CO2 and CO and other trace gassesBalanced with .5 mw engine for process CHP

Planning variation requiredPermit variation required

Gas Injection Plant

Planning

Conditions discharged on current planning

Variation in process - conditions to be issued

Time Lines

Ground raising has commenced

Civils - out to tendercommence April 2012

Plant - detailed design underwayfinal contract 13 January 2012on site commencement 2012

Operation - first waste reception mid April 2013final handover November 2013

Thank you

Questions?