Les systèmes bio-électrochimiques comme technologie d'avenir · 2016-04-25 · Les systèmes...

HES-SO Valais-Wallis

Les systèmes bio-électrochimiques comme technologie d'avenir

Maxime Blatter

HES-SO Valais-Wallis / Institut Technologies du Vivant

Lab. Biotechnologie Chimique


Généralités:

Matière

organique BES

Electricité

Hydrogène

gaz

H2

Autres produits

de valeur NaOH / CH4 / EtOH / BuOH


Source de matière organique / microorganismes :

Déchets

agricoles

Déchets

du secteur

alimentaire

Déjections

humaines

De nombreux microorganismes peuvent se développer

dans les STEP


Considerations économiques:

Potential énergétique contenu dans les eaux usées > Energie

nécessaire à leurs traitement.

Implémenter les systèmes bioélectrochimiques

directement dans les stations de traitement des

eaux.

Traitement des eaux usées : 3.1 milliards $ (Europe, 2010)


Principe de fonctionement des BES:

Anod

e

Cath

od

e

V

Mic

roorg

anis

mes

Mic

roorg

anis

mes

Matière organique

H+

CO2 e-

PS

e-

2H2O + 2e-

H2 + 2 OH-


Matériel de construction:

Anode: Reticulum vitreous carbone (RVC)

Cathode: Platinized RVC

Membrane: Proton exchange membrane (Nafion type)


L’utilité du biofilm :

Introduction

Bioelectrochemical systems:

Wastewater treatment, bioenergy and valuable

chemicals delivered by bacteriaGlobally, billions of euros are spent treating trillions of litres of wastewater every year, consuming substantial amounts of

energy. However, this wastewater could act as a renewable resource, saving significant quantities of energy and money,

as it contains organic pollutants which can be used to produce electricity, hydrogen and high-value chemicals, such as

caustic soda. This can be achieved if the organic matter is broken down by electrically-active bacteria in an electrochemical

cell, which, at the same time, helps clean up the wastewater. Examples of such ‘bioelectrochemical systems’ (BES) are

microbial fuel cells (MFCs) and microbial electrolysis cells (MECs).

Box 1:

Wastewater treatment in Europe

EU Member States are obliged to collect and treat domestic and industrial

wastewater from urban areas under the Urban Wastewater Directive1.

Every year, wastewater is dealt with in plants across the EU with the

collective treatment capacity equivalent to around 550 Million ‘population

equivalents’ (European Commission, 2011). Population equivalent is a

concept used in the wastewater sector, and is the theoretical measure of

the organic pollutant load generated by a human being, and includes both

domestic and industrial wastewater flow.

1. http://ec.europa.eu/environment/water/water-urbanwaste/index_en.html

Figure 1. Scanning electron microscopic images of a mixed culture bioelectrocatalytic anodic biof lm derived from wastewater on a carbon f bre electrode, at dif erent magnif cations of 5 and 30 µm.

T is Future Brief from Science for Environment Policy

examines the use of BES to treat wastewater and generate

electricity, hydrogen and valuable chemicals.

Although further work is needed to understand

important biological and engineering issues that

underpin the biotechnology, laboratory experiments

have shown BES can work. So far, however, only a few

pilot studies have been run in real-world conditions

and more pilot studies and scaled-up demonstration

projects are needed to prove the reliability of the

systems. In addition, costs have to be competitive with

other wastewater treatment and chemical production

processes before the biotechnology can be adopted on

a commercial scale. However, researchers are optimistic

that commercial installations could be realised in two to

f ve years’ time.

Les microorganismes forment un biofilm sur l’anode


Différence entre MFC et MEC :

MFC MEC


Cellule microbienne de désalinisation (MDC):

Basée sur le

principe de

migration des

espèces chimique

chargées.


Production d’électricité et traîtement des eaux usées:

Travail en cours à la HES-SO Valais-Wallis.

Publication : M. Sugnaux, S. Mermoud, A. F. da Costa, M. Happe & F. Fischer (2013). Bioresource Technology, 148, 567-573.

Application:

Electricity, Waste Treatment (the classic use)

A

O2 H

2 O

Ox

ida

tion

Waste Water H+

e-

Electricity

e-

Microbe

On-going work at HESSO Valais.

Sugnaux, M., Mermoud, S., da Costa, A. F., Happe, M., & Fischer, F. (2013). Bioresource Technology, 148, 567-573.


Production de Base (NaOH) à partir des eaux usées:

Publication : M. Blatter, M. Sugnaux, C. Comninellis, K. Nealson & F. Fischer (2016). En soumission.

A

H2 O

OH

-

Ox

ida

tion

Waste Water

Application:

Base (NaOH) production from waste water

Na+

e- e-

Microbes

Chemical Base (NaOH)

Cathode reaction: O2 + 4e- + 2H+ + 2 Na+ à 2 NaOH

M. Blatter, M. Sugnaux, C. Comninellis, K. Nealson, F. Fischer, 2016 in submission.

A

H2 O

OH

-

Oxid

atio

n

Waste Water

Application:

Base (NaOH) production from waste water

Na+

e- e-

Microbes

Chemical Base (NaOH)

Cathode reaction: O2 + 4e- + 2H+ + 2 Na+ à 2 NaOH

M. Blatter, M. Sugnaux, C. Comninellis, K. Nealson, F. Fischer, 2016 in submission.


Formation de Bio-Méthane:

Publication : M. Sugnaux, M. Happe, C. P. Cachelin, F. Fischer, en péparation

Anode

CO

2 C

H4

Ox

ida

tion

Potentiostat

Reference

+ -

H+

e- e-

Application: Bio-Electro-Methanisation

VA

Cathode

Wet Activated Sludge à CH4 + «CO2»

Methane

M. Sugnaux, M. Happe, C. P. Cachelin, F. Fischer, in preparation.

Waste water

Anode

CO

2 C

H4

Ox

ida

tion

Potentiostat

Reference

+ -

H+

e- e-

Application: Bio-Electro-Methanisation

VA

Cathode

Wet Activated Sludge à CH4 + «CO2»

Methane


Waste water


Anode

2H

+ H

2

Oxid

atio

n

Potentiostat

Reference

+ -

H+

e- e-

Application:

Bio-Hydrogen Evolution Reaction

VA

Cathode

C6H12O6 + 6H2O à 6CO2 + 6H2

Hydrogen

Overpotential only 0.13 V


Microbes

Waste

water

Formation de Bio-Hydrogène:

Publication : M. Sugnaux, M. Happe, C. P. Cachelin, F. Fischer, en péparation


Réduction du CO2 par des Microalgues:

Travail de bachelor en cours à la HES-SO Valais-Wallis.

A

Microalgae on

cathode

O2 H

2 O

Ox

ida

tion

CO2

Application:

CO2 Reduction by Microalgae

H+

e-

Light

H2

Electricity

e-

Chlamydomonas

reinhardtii

Microbes

Cathode reaction: ½O2 + 2e- + 2H+ à H2O

And other effects?

On-going bachelor work at HESSO Valais.

Waste water

A

Microalgae on

cathode

O2 H

2 O

Ox

ida

tion

CO2

Application:

CO2 Reduction by Microalgae

H+

e-

Light

H2

Electricity

e-

Chlamydomonas

reinhardtii

Microbes

Cathode reaction: ½O2 + 2e- + 2H+ à H2O

And other effects?

On-going bachelor work at HESSO Valais.

Waste water


PO43-

Réserves minières : 50-100 ans

Présent dans les stations d’épuration

Phosphate est un

composant essentiel

des engrais

Projets de Recherche: Extraction du phosphate à partir des eaux usées

Struvite BES

Moyen de récuperation


Projets de Recherche: Extraction du phosphate à partir des eaux usées

A

Fe

P P

O4

Ox

ida

tion

Waste Water

Application:

Phosphate extraction from waste

H+

e- e-

Microbes

Cathode reaction (simplified): FeP(s) à Fen+ + PO43-

Fertilizer and

Industrial Phosphor

FeP Sludge

On-going work at HESSO Valais

Happe, M., Sugnaux, M., Cachelin, C. P., Stauffer, M., Zufferey, G., Kahoun, T., ... & Fischer, F. (2016). Bioresource Technology, 200, 435-443.

A

Fe

P P

O4

Ox

ida

tion

Waste Water

Application:

Phosphate extraction from waste

H+

e- e-

Microbes

Cathode reaction (simplified): FeP(s) à Fen+ + PO43-

Fertilizer and

Industrial Phosphor

FeP Sludge

On-going work at HESSO Valais

Happe, M., Sugnaux, M., Cachelin, C. P., Stauffer, M., Zufferey, G., Kahoun, T., ... & Fischer, F. (2016). Bioresource Technology, 200, 435-443.

Travail en cours à la HES-SO Valais-Wallis.

Publication : M. Happe, M. Sugnaux, C. P. Cachelin, M. Stauffer, G. Zufferey, T. Kahoun, […] & F. Fischer (2016). Bioresource

Technology, 200, 435-443


Ash/sludge layer

Unreacted core

Reactive area C

on

ce

ntr

ation

of

so

lid r

ea

ge

nt

R R rc rc 0

Time Low conversion High conversion

Projets de Recherche (MFC / MEC): Extraction du phosphate à partir des eaux usées

OH-

OH- FeP

OH-

PO43-

PO43- d


Projets de Recherche (MFC / MEC): Extraction du phosphate à partir des eaux usées

ReactionChemistry&Engineering ARTICLE

Thisjournalis©TheRoyalSocietyofChemistry2016 React.Chem.Eng.,2016,00,1-3|5

Pleasedonotadjustmargins


3.1.2Influenceoftemperature

Thetemperatureinfluencedthephosphateremobilisation

rate substantially.Asa referencepoint, a remobilisation

mixturewithapHof12.4wasusedasitled,at25°C,toa

relativelyslowreaction(Fig.3).Whenrisingthetemperatureto

40°Cthereactionratewaswellenhancedandwithafurther

augmentation(70°C)theremobilisationbecameevenfaster

(Fig.4).Anincreaseofthetemperatureresultedinahigher

reactionrateconstantkobs.Thereactionbecame2.5times

fasterat40°C(kobs=4.5.10

-5s-1)incomparisonto25°C(kobs=

1.7.10

-5s

-1)and6timesmorerapidwhenopposingto15°C

(kobs=7.3.10

-6s-1).Duetothattemperaturedependency,the

activationenergywaspossibletodeterminebytheArrhenius’

law(Eq.9)tobeEa=55kJ/mol.Thistemperaturedependence

wasnotvisibleinotherwork23.Theeffectofthetemperature

remainsprobablyinvisibleatimportantpH,hinderedbythe

influenceoftheimportanthydroxideconcentration.Herethe

initialpHwassetto12.4toobservetheconsequencesofan

increaseoftemperatureandevenamoderatetemperature

risealreadyimprovestheremobilisationprocesssubstantially

(Fig.4).

3.1.3Influenceofstirringvelocity

Ahigherstirringrateacceleratedtheremobilisationina

consequentialmanner.Doublingthevelocityfrom200to400

rpm almost quadrupled the percentage of phosphate

remobilisedafteroneday,from25to92%(Fig.5).Ahigher

stirringrateinducedagreatermobility(! (! ))ofthechemical

basewithinthesludgematrix.Thus,ahighermasstransfer

(!! ,! ! )duetoconvectionwasachieved(Eq.14)andenhanced

remobilisationratesbecamepossible.

!! ,! ! = ! ! ! (! ) (14)

3.1.4Influenceofsludgeconcentration

Thedigestedsewagesludgewaspartlydissolvedinwater

as a suspension. When too much sludge was used it

accumulatedontopofthesuspension.Thiseffectoccurred

when exceeding a sludge concentration of 20g/L. The

investigation was thus limited to smaller concentrations

(<20g/L).Inthatexperimentalrangethesludgematrixwould

thickenasfunctionoftheincreasemediumconcentrationand

thereactionbetweenironphosphateandhydroxideions

should be more difficult (Sec.2.5) implying lower

remobilisation yields, what was experimentally verified

(Fig.6A). When using a concentration of 6.7g/L the

remobilisationefficiencywas68%after20hagainstonly26%

with20g/L.Thehighersludgeconcentrationinvolvedagreater

iron phosphate content, which leads to a higher base

consumption.Asaconsequence,thepHofthebulkmedium

Figure3:PhosphateremobilisationyieldsasafunctionofpH.Remobilisation

conditions:10g/ldigestedsewagesludge,26µmaverageparticlesdiameter,

25°C,variablepHand300rpm.

Figure4:Phosphateremobilisationyieldsasafunctionofprocesstemperature.

Remobilisationconditions:10g/ldigestedsewagesludge,26µmaverage

particlesdiameter,threedifferenttemperatures,pH=12.4and300rpm.

Figure 5: Phosphate remobilisationyieldsasa function of stirring rates.


particlesdiameter,25°C,pH=12.7andfourdifferentstirringrates.

Figure3: Figure4:

Figure5:


Thisjournalis©TheRoyalSocietyofChemistry2016 React.Chem.Eng. ,2016,00,1-3|5














1.7.10

-5s


(kobs=7.3.10










(Fig.4).










!! ,! ! = ! ! ! (! ) (14)


























Figure3: Figure4:

Figure5:


Thisjournalis©TheRoyalSocietyofChemistry2016 React.Chem.Eng.,2016,00,1-3|5














1.7.10

-5s


(kobs=7.3.10










(Fig.4).










!! ,! ! = ! ! ! (! ) (14)


























Figure3: Figure4:

Figure5:

Paramètres importants:

Témperature, pH, agitation

Taux de recyclage: 94%


Challenges futurs pour application commerciale :

• Construire des unités pouvant traîter de larges volumes

• Augmenter la densité de courrant générée par le système

• Eliminer les pertes électrochimiques

• Utiliser du matériel de construction plus abordable

• Obtenir une meilleure compréhension des procédés biologiques

impliqués


Bibliographie:

• European commission, Bioelectrochemical systems: wastewater treatment,

bioenergy and valuable chemicals delivered by bacteria. Science for

Environment Policy, 2013.

• D. Pant et al., Bioelectrochemical systems (BES) for sustainable energy

production and product recovery from organic wastes and industrial

wastewaters, RSC Advances, 2012, 2, 1248-1263.

• R. A. Rozendal et al., Towards practical implementation of bioelectrochemical

wastewater treatment. Trends Biotechnol., 2008, 8, 450-459.

• B. E. Logan et al., Microbial Fuel Cells: Methodology and Technology.

Environ. Sci. Technol., 2006, 40, 5181-5192.

Les systèmes bio-électrochimiques comme technologie d'avenir · 2016-04-25 · Les systèmes...

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