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Integration of New Biowaste Facilities on Waste Water Treatment Infrastructure

Dorian Harrison, Technical Director (Monsal)

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Project Brief

• Develop AD Assets / Strategy in Scotland for Biowaste• Plant 1 - 30,000 tpa (Cumbernauld)• Plant 2 - 40,000 tpa (Prestwick)• Plant 3 - 40,000 tpa (Johnstone)

• Merchant Site

• Category 3 Material

• Separate Packaged Feed Materials

• Produce High Quality (PAS110) Product

• Maximise Revenue from Energy Generation

• Integrate into Existing Facility

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Project Procurement & Team

• Initial OJEC Notice (short list 6 bidders)

• Phase 1 – Permit Design Development

• Phase 2 – Detail Design Development

• Phase 3 – Construction Phase

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Project Overview

• Existing Open Windrow and IVC Composting Facility• Mixed green waste• Catering waste• Slurries (Odour)

• Current Capacity 40,000 tpa

• New Biowaste AD – Additional 30,000 tpa• Kerbside collection (source segregated)• Packaged food waste• Category 3• Commercial and industrial (C&I)• Slurries

• 1MWe Generation

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Cumbernauld - Site History

• Site History• Operated as Deerdykes STW• Converted to open windrow composting facility (2003)• In vessel composting completed (2008)• Merchant AD facility (2010)

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Integration Issues – WwTW Upgrade to Biowaste

• Difficulties• Traffic management• Electrical Connection • Discharge Consent • Permit Modification• Planning Permission• Product (PAS110 / Waste Exemption License)

• Benefits• Dilution Effluent• Existing Discharge to Sewer / Liquor Treatment?• Existing Logistics• Trained Operations Staff• Grid Connection / Generating Capacity

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Permitting Issues

• Odour at boundary 1.5OUe• NOx, SOx emissions • Noise• Effluent (liquor treatment)• Normal operation• Abnormal operation• Best Available Technology

• Environmental risk assessment integral with design risk assessment• Modelling of emissions (noise, NOx, SOx, odour)• Design to minimise emissions• Environmental HAZOP to look at risks • Visit working sites to familiarise• Define BAT

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Commercial Viability

• Revenue Streams (Maximise!)• Gate fee• Power• Product

• Opex Costs (Minimise!)• Parasitic power• Fuel costs• Manpower• Product?

• Infrastructure Cost • Minimise development costs (phased contract)• Biowaste AD asset specification• Development support

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30,000 Biowaste plant– Short Mass Balance

Pre-Processing AD plant Biogas CHP

Waste

30,000 tpa Power

1 MWe

Compost

16,600 tpa

Makeup Water40 - 90 m3/d

Biogas production

439 m3/hWaste Water

36 m3/d

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Monsal Biowaste Flowsheet

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Feed Preparation for Digestion

• Up to 20% Contamination

• Solids 20% to 40%

• This is what we get

• What we Want• Solids ~ 10% by weight• Contamination < 0.25% in feed

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Cleaning up Biowaste – how it works

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Ideal Feed to Digester

• Liquified Slurry Feed (Wet Digestion)

• 10% DS

• 12mm screened

• Low Contaminants

• PAS110 req <0.5% by Weight

• Digestion Concentrates Contamination• 0.25% Feed = 0.5% Cake

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Required Product

• Contamination < 0.5%• PAS110 compliant• Product• 25 – 35% dry solids

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Conclusions

• Co-development of Biowaste AD with WW assets minimises development costs & programme

• Planning• Permitting• Synergises – liquors, power, infrastructure, staff.

• Water industry pedigree of client and technology provider ensures robust quality and professional project delivery

• Biowaste asset standard optimised to deliver good commercial IRR

• Model can be expanded rapidly across Scotland (Plants 2 & 3) delivering:• 110,000 tpa capacity

• 4 MWe + renewable energy• Valuable compost for recycling

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Acknowledgments

• Scottish Water Horizons• Donald MacBrayne• Helen Gillard• Kristine Leitch

• Enviros• Jonty Olufsen• Joe Short

• HBS• Andrew Russell• Bill Taylor

• SEPA

• WRAP (demonstrator program)

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Thank You

Dorian HarrisonTechnical Director (Monsal)

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Magnetic Separation (for source segregated?)

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Waste Dissolvers

• Liquify Organic Material

• Separate out Heavy Contaminants

• Float Light Contaminants

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Animal By-Products

• Category 1• Incineration

• Category 2

• Rendering• 133oC for 20 minutes as a batch• 3 bar pressure• No Disposal to Agricultural Land

• Category 3• 70oC for 1 hour as a batch

• <12mm in one plane

• Catering Waste (UK)• Meat Excluded• Biogas - 57C for 5 hour as a batch• <50mm in one plane• 18 days storage