Anaerobic Digestion Presentation

8/13/2019 Anaerobic Digestion Presentation

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AGRUP DE RECERCA EN

BIOTECNOLOGIA AMBIENTALDEPARTAMENT DENGINYERIA QUMICA

ANAEROBIC DIGESTION

Break the ice

Sergi Astals Joan Mata

EPROBIO - Foggia - June 2011

ITXARXA DE CENTRESDE SUPORT A LAINNOVACI TECNOLGICA

ITXARXA DE CENTRESDE SUPORT A LAINNOVACI TECNOLGICA


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INDEX OF CONTENTS

What is anaerobic digestion?

Anaerobic digestion advantages

Which waste can be digested?

What is biogas?

Biogas as a renewable source of energy


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What come to your mind when you listen anaerobic digestion?


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AD is a biological technology which, in the absence of oxygen,

decomposes organic matter.

The breakdown of the biodegradable organic matter produce stable

organic residues and biogas (a mixture of methane (CH4) and carbon

dioxide (CO2)).

Anaerobic conditions requires the absence of oxidizers compounds*:

- Oxygen (O2)

- Nitrate (NO3-) and nitrite (NO2

-)

- Sulphates (SO42-)

* Substances that have the ability to oxidize other substances. They gain electrons, they are reduced, so other

compounds have to loss it (oxidized).


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AD take place in the nature where organic matter is present and the

oxygen concentration is negligible:

- Stomachs of ruminants

- Sediments of lakes

- Landfills

- Sewers

-


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Anaerobic digestion advantages

The main advantages of the AD technology are:

- Stabilize organic matter

- Feasible for a wide variety of waste and flow rates

- Reduce greenhouse gases emission global warming

- Low sludge production

- Positive energy balance

Energy from biogas

Low operational cost

- No or very little use of chemicals


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What industrial wastewaters are anaerobically digested?

AD is used as an end of pipe treatment for:

Agro-food industry: Sugar, potato, starch, fruit, vegetables, dairy, bakery

Beverage: Beer, soft drinks, wine, fruit juices, coffee

Pulp and paper industry: mechanical pulp, straw, bagasse

Others: pharmaceutical, chemical, municipal sewage, landfill leachate


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What is biogas?

Biogas is a methane rich flammable gas that results from the

decomposition of organic waste materials.

Which gases can be found in biogas:

> Mayor compounds:

- Methane (CH4) [60 70 %]

- Carbon dioxide (CO2) [40 30%]

> Minor compounds:

- Hydrogen sulphide (H2S) > odour problems

- Ammonia (NH3) > odour problems

- Hydrogen (H2)

-


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Biogas energy value

Exercise b:

How much water can be boil with 1 m3 of biogas?

Data of water:

Initial temperature = 25 C

Latent heat vaporization ()= 2,260 KJ/m3

Heat capacity (C) = 4.18 KJ/(Kg C)

Biogas lower heating value = 22,400 KJ/m3

Exercise c:

How much water can be boil with 1 m3

of biogas isthe burner efficiency is 0.75?

Exercise a:

How much water can be heat to 80 C with 1 m3 of

biogas?


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Biogas energy value

Exercise b:

Exercise c:

( ) ( ) ( ) KJ22,400KgXKgKJ

2260kgXC20100CKg

KJ

4.18 =

+

X = 8.64 Kg

( ) ( ) ( ) 0.75KJ22,400KgXKg

KJ2260kgXC20100

CKg

KJ4.18 =

+

X = 6.48 Kg

( ) ( ) KJ22,400kgXC20100CKg

KJ4.18 =

Exercise a:

X = 66.99 Kg


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Energy conversion factors

1 KWh = 3600 KJ

1 KJ = 2.34 10-11 ktep*

1 KWh = 0.8410-7 ktep

* tep: tonne of oil equivalent (the amount of energy released by burning one tonne of crude oil)


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Biogas uses

Biogas, as a renewable source of energy, is becoming more

important as petrol cost continue to rise.

Even some AD plant still burn the biogas in flares, digester gases are

used as fuel for:

- Heating anaerobic digesters and plant buildings

- To operate cogeneration unit

- To operate blowers, pumps,

Household and/or communities

AD can use biogas for:

- heat water

- cook

- light

EurObservER 2002


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EurObservER 2008

Landfill gas

Urban sewage and industrial

effluents

Agricultural waste, MSW,

OFMSW, co-digestion plants


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EurObservER 2008 and 2010

Landfill gasUrban sewage and industrial

effluents

Agricultural waste, MSW,

OFMSW, co-digestion plants


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EurObservER 2010

The biogas sector has never before aroused so much attention as it does today.

Interest has been fired by the introduction of regulatory directives

- Council Directive 1999/31/EC of 26 April 1999on the landfill of waste

- Council Directive 2008/98/EC on waste

- Council Directive 2009/28/EC of 23 April 2009 on the promotion of the use of

energy from renewable sources

Biogas is mainly produced form waste treatment. However, energy crops are growing

Biogas production has been stimulated to farm holders to reduce their energy

dependency and diversify their incomes.

Countries want to reduce their dependency on natural gas, purify biogas to obtain

biomethane which can be injected in the natural gas grid


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Country Installed Power (kW) / kWh Bonus

< 500 0,140

> 500 0,100

< 150 0,117 plus 0.07/kWh using energy crops

150 - 500 0,092 plus 0.01/kWh if a 30% of manure is used

500-5000 0,083 plus 0.03/kWh for CHP unit

5000-2000 0,078

< 100 0,165 minus 25% for co-digestion

100 - 500 0,145

500 - 1000 0,125

> 1000 0,103

< 150 0,093 plus 0,02 for methanisation

> 2000 0,078

Spain

Germany

Austria

France

Biogas price

Anaerobic Digestion Presentation

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