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Anaerobic Digestion

&

Municipal Waste Water Treatment

A Project Road-Map

For Bulgaria

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Presentation Structure

1. Anaerobic Digestion & Waste Water TreatmentWhat are we talking about ?What are the first questions municipalities need toanswer?

2. Feedstocksjust sewage sludge? or can other feed-stocks be used?

What is the gas yield from sewage sludge and otherfeedstocks?

3. What does AD cost? Does it make any money? Costs & Possible Revenues An Outline Action Plan

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AD Advantages

- less sludge to dispose of after AD (reduces cost$ for theWWTP)

- sludge can be spread on agricultural land or $old- AD plants can be compact- Sewage sludge is stabilised by AD- bioga$ production

AD Disadvantages

- no nitrogen elimination,- process control & know-how needed,- not able to easily adapt to large changes in flow volumes

Why AD?

And of course it is possible to make $$$$$$$ from AD

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PWRWhat are we talking about?

Anaerobic Digestion & Waste Water Treatment

Henriskdal WWTP - Sweden

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Question 1a & 1b for Municipalities

1a: What volume of waste water occur

1b. What is the Dry Matter Content of Your Waste Water?

1. Measure off-line through drying and weighing (but only

measures samples not flows)

2. Microwave measurement on-line - can measure a flowwith sampling rate of seconds (but only handles DMs of 3 to15%).

3. Near Infrared Spectroscopy (NIRS) on-line technique canbe used at various points in the AD process

Methods

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Question 2 for Municipalities

What is the Energy Content ($$$) of Your Waste Water?

1. COD: Chemical Oxygen Demand, indirect measurement of

organic compounds (but no correlation to energy content)

2. Calorimetry: dry the sample and then burn it & measureenergy

Traditional Methods

Problem!!: tends to underestimate energy content of

waste water by up to 20%* becausedrying causes loss of volatile matter

*Source: Elizabeth Heidrich, PhD student, Newcastle University UK.

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PWRDecision Point 1

Build MWWSystem Only

Build MWWSystem &Plan for AD(later)

Build MWWSystem &AD

Decision Point 2

AD using

only MWWsludge

AD &Co-digestion

BudgetIssue

Availability ofother materialfor AD

Suitability ofother materialfor AD

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PWRGas Yields

&Why Co-Digestion is (very) desirable

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PWRMore Data on Gas Yields

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Question 3

a. How much material for co-digestion is available?b. Is it available on a regular basis? (seasonal basis?)c. Could the supplier be charged for disposing of it (= revenue stream)d. How far away is it (transport costs an issue?)

Is the material viable (both from an AD and financialpoint of view for inclusion in the AD project)

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PWRIs Co-Digestion Worth it?

1. Biogas to produce electricity2. Biogas to fuel vehicles3. Pelletised sluge to use in, e.g. cement production*4. Acceptance fees for industrial/commercial waste

* Biogasmax Report: WWTP Bern

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AD forMunicipal Waste Water Treatment

1. High rate system (short hydraulic retention times)(usually solids retention time = hydraulic retention time)

2. Single stage system (i.e. one AD tank)

3. But several different processes to choose from:

WABIO one step systemBTA single stageLinde KCA process

4. Most common process: activated sludge process(as used in Swedish AD system)

Budget,flex

ibilityofthe

process,space

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PWRADSystem Size

An example from XXXXXXX for one house

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Location: Juhned, Germany, 800 population

System: AD plant using local biomass (animal manure) plusCHP/district heating

Politics: System is communally financed & ownedEnd Result: Export 50% of power produced, 99% self-sufficient in

energy for heating

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WWTP Luzern 2000 to 2006 wastewater treatment plant wasredeveloped (to include AD)

Total AD module costs 750 /m digester volume (WETT 2009)10 % costs for machine technology

90 % for physical facilities (KOBEL and BGUE 2008).Overhead expenses - approval and planning 10 % totalinvestment costs (KTBL 2007).

Pumps & controls (import?)

Tanks, bases etc (make locally?)

Capital Costs A Swiss Example

Source: Assessment Report on Operational Experience Biogasmax

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PWRCapital Costs II

Capex Costs for Electricity Generation: Euro 750/kW(Source: 2008 SLR study)

Similar costs for biogas into gas grid or use with gas engine

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PWROperating Costs vs Gas Market Prices I

Cost to produce 1m3 biogas from the AD process = Euro 0.09(From Luzern Switzerland*)

Methane content = 62.5%

Converting to kwhrs = (approx) 7kwhrs (assuming 11kwhrs per m3 natural gas)

Cost to produce 1kwhrs of gas from AD with sewage sludge = Euro 0.013

Current Bulgarian (domestic) gas prices (EC web site) = Euro 0.0351/kWhrCurrent Bulgarian (industrial) gas prices (EC web site) = Euro 0.0215/kWhr

Biogas prices for vehicles: Euro 0.42/m3

Lesson: AD gas can be produced @ 60% less than the selling price ofdomestic gas, 35% less than the selling price of industrial gas and66% less than the selling price for gas for vehicles.

*Source: Assessment Report on Operational Experience Biogasmax

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Rubbish collection vehiclesfuelled by.. rubbish

Combined waste treatmentplant & bus depot with thebuses power by..

France

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Cost to produce 1m3 biogas from the AD process = Euro 0.19(From Henriksdal Sweden*)

Methane content = 65%

Converting to kwhrs = (approx) 7kwhrs (assuming 11kwhrs per m3 natural gas)

Cost to produce 1kwhrs of gas from AD with sewage sludge = Euro 0.027

Current Swedish (domestic) gas prices (EC web site) = Euro 0.10/kWhrCurrent Swedish (industrial) gas prices (EC web site) = Euro 0.05/kWhr

Lesson: Even in a high cost location like Sweden AD & biogas isinteresting as a method to turn waste into revenue

*Source: Assessment Report on Operational Experience Biogasmax

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Commercial Considerations&

Group Action

1. Do Bulgarian municipalities have similar types ofwaste water to treat? (probably)

2. Should Bulgarian municipalities group together

depending on the flow rates of waste water (and thusthe size and type of AD system they might need) andact as a single unit when purchasing AD systems?

3. Do you think that the price for a single AD systemmight be different from the price if 10 or 100 are

purchased?

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More Decisions

Decision Point 3

Collaborate withother municipalities

Decision Point 4

What to do with the gas?

Option 1Generate Electricity(CHP?)

Option 2Gas for Vehicles

Option 3Sell to gas grid

Clean the gas

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1. Detailed feasibility study (Answer Questions 1a, 1b & 2 &.)2. Effective business plan

2a What size of plant is appropriate2b What type of plant is appropriate)

2c What other feed-stock is available?2d Citizens participation (partners?) of the bioenergy plant2e Define revenue streams are these realistic

Project Success Criteria

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Key Documents

Web site: www.biogasmax.eu(EU project)

Reports Assessment Report on Operational Experience

Final Assessment Report on Residual Materials

Decision Makers Guide: How to Implement aBiomethane Project (for vehicles)

Arcadis: Final Report Assessment of theOptions to Improve the management of Bio-

waste in Europe

http://www.biogasmax.eu/http://www.biogasmax.eu/

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AD & Improved Gas Yields

1. Thermal Hydrolysis (e.g CAMBI method)2. Chemical Hydrolysis3. Thermo-Chemical Hydrolysis4. Ozone Treatment

5. Ultrasound6. Electroporation7. Addition of Enzymes

Reference: Increased Gas Production @ the Henriksdal Waste Water Treatment Plant ( www.biogasmax.eu ).

http://www.biogasmax.eu/http://www.biogasmax.eu/