Environmental Sustainability Assessment of a Microalgae ... · Heat Soil conditioner 2 MaB-flocs plants are integrated: Plant L (linearly up-scaled plant) Plant SEM (plant L with

Environmental Sustainability Assessment of a Microalgae

Raceway Pond Treating Wastewater from a Recirculating

Aquaculture System

From Upscaling to System Integration

Sophie Sfez(a), Sofie Van Den Hende(b), Sue Ellen Taelman(a), Steven De

4th International Congress on Sustainability Science & Engineering

26-29 May 2015

Sustainable Pathways for Algal Bioenergy Sustainable Pathways for Algal Bioenergy

Sophie Sfez(a), Sofie Van Den Hende(b), Sue Ellen Taelman(a), Steven De

Meester(a), Jo Dewulf(a)

(a) Department of Sustainable Organic Chemistry and Technology, Ghent University, Coupure Links 653, B-

9000 Ghent, Belgium

(b) Laboratory for Industrial Water and Eco-Technology (LIWET), Faculty of Bioscience Engineering, Ghent

University, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium

Introduction

EnAlgae: INTERREG IVB North West Strategic Initiative (03/2011 – 06/2015)

9 pilot scale algae cultivation sites (micro- and macroalgae)

Sustainable Pathways for Algal Bioenergy

• In Roeselare, Belgium: Algae-based wastewater treatment plant, treating wastewater from a pikeperch recirculating aquaculture systems (RAS)

Aquaculture: fast growing sector competing for freshwater resources

RASs: promising option to mitigate the environmental footprint of aquaculture systems

Introduction

Settling tank

Backwash

Backwash supernatant

Biofilters

UVO2

Recirculating aquaculture systemAlgae-based wastewater treatment

system


tank

Fish sludge

wastewater

Fish ponds Drum filters

Biofilters

Water

Anaerobic digestion

The MaB-floc technology tested in 2013 in Belgium at pilot scale to treat pikeperch aquaculture wastewater from the Aquaculture Research Center of Inagro (Belgium)

As they grow, MaB-flocs need to be harvested, delivering a new source of biomass: valorisation as shrimp feed and anaerobic digestion were tested at pilot scale

MaB-flocs: bioflocculating consortium of bacteria and microalgae

Introduction

� Industry needs insights to know which direction to take


Goal of the studyGoal 1: Assess the environmental footprint of a pilot MaB-floc SBR treating

pikeperch culture WW and identify its improvement potential

Goal 2: Forecast the most sustainable valorisation pathway for MaB-flocs in the framework of an integrated aquaculture waste treatment system at industrial scale

Pilot MaB-floc SBR treating pikeperch wastewater (real case)

Studied MaB-floc based WWT plants

MaB-floc

liquor

Backwash

supernatant

Electricity

Supernatant

Flue

gasLandSunlightNatural

gas

Heat

MaB-floc

raceway pond

To

stir

rin

g p

um

ps

Settling

tank

Electricity

1 pondArea: 12 m2

Volume: 28 m3

Flow: 2.59 m3 day-1


Effluent

water

MaB-floc

liquor

Van Den Hende 2014


Hypothetical up-scaled cases (1000 m3 of WW treated per day):

L: linearly up-scaled MaB-floc plant


41 pondsArea: 245 m2 pond-1

Volume: 98 m3 pond-1

Flow: 24.5 m3 day-1 pond-1

50 m

5 m

Electricity

Flue gas

Sunlight

Natural gasHeat

Supernatant

MaB-floc

raceway

pond

To stirring

pumps

Blower


Flow: 24.5 m3 day-1 pond-1

41 reactors =

1ha of cultivation

Effluent

WaterLand

Sunlight

Settling

tank

Electricity

MaB-floc

liquor




S: linearly up-scaled MaB-floc plant with improved stirring system



Propeller pump22 W m-2

Paddle wheel 5.1 W m-2





E: linearly up-scaled MaB-floc plant with Belgian electricity mix replaced by 100% wind energy







E: linearly up-scaled MaB-floc plant with Belgian electricity mix replaced by 100% wind energy

M: linearly up-scaled MaB-floc plant with MaB-floc productivity



M: linearly up-scaled MaB-floc plant with MaB-floc productivity improved by 30%

Valorisation of MaB-flocs as shrimp feed

Studied integrated system

Backwash

wastewater

Heat

Treated backwash supernatant released in the sewage system

DigestateElectricity

Heat

Valorisation as shrimp feed

Fish sludgeDigester

Maize silage

Shrimp feed

Drying

Soil conditioner

Raceway ponds

MaB-floc liquor Dewatering

CHPBiogas Electricity to the grid

Pikeperch RAS Settling Milling

Three scenarios are compared:


Soil conditioner

Valorisation as biogas

Soil conditioner

MaB-floc liquor

Backwash

wastewater

Heat


Fish sludge

Maize silage

Digester Biogas

DigestateRaceway

ponds Dewatering

CHPElectricityto the grid

Pikeperch RAS Settling

Valorisation of MaB-flocs as biogas

Three scenarios are compared:Valorisation of MaB-flocs as shrimp feed

Valorisation of MaB-flocs as biogas

Baseline scenario

Studied integrated system

Backwash

wastewater

Backwash supernatant released in the sewage system

Electricity

HeatPikeperch

RAS

Fish sludge

Settling

Maize silageBiogas

Electricity to the grid

Digester CHP


DigestateElectricityMaize silage

Soil conditionerHeat

2 MaB-flocs plants are integrated:� Plant L (linearly up-scaled plant)

� Plant SEM (plant L with the 3 improvements implemented

50 m

5 m

41 reactors =

1ha of cultivation

Electricity

Effluent

Water

Flue gas

Land

Sunlight

Natural gasHeat

Settling

tank

Electricity

Supernatant

MaB-floc

raceway

pond

To stirring

pumps

MaB-floc

liquor

Blower

50 m

5 m

41 reactors =

1ha of cultivation

Electricity

Effluent

Water

Flue gas

Land

Sunlight

Natural gasHeat

Settling

tank

Electricity

Supernatant

MaB-floc

raceway

pond

To stirring

pumps

MaB-floc

liquor

Blower

+ + +

Env. Sustainability Analysis

Functional unit

Life Cycle Assessment (LCA), ISO standards 14040 & 14044

Goal and scope

definition

Inte

rpre

tati

on

Goal 1: comparison of the 4 MaB-floc

based WWTP

Goal 2: SA of the integration of MaB-floc based WWTP in

an aquaculture system

Production of 1 kg TSS MaB-floc liquor

Treatment of 1 m3

of wastewater

Syst. boundaries Cradle-to-gate


Inventory

analysis

Impact

assessment

Inte

rpre

tati

on

Foreground system

Pilot: site dataUp-scaled: pilot data + literature

Data from up-scaled plant + ecoinvent v 2.2 + literature

Background system

ecoinvent v 2.2 + literature

Resource consumption (CEENE 2013) � resource efficiency analysis

Global warming potential (IPCC 2007) � air emission efficiency analysis

Marine and freshwater eutrophication (ReCiPe 2013) � water emission efficiency analysis

LCA results: environmental sustainability of the MaB-floc based WWTP

Resource footprint (CEENE results)

50

100

150

200

250

300

350

400

450

ex

,CEEN

Ek

g-1

Ma

B-f

loc T

SS

Total CEENE: 848 MJ kg-1 MaB-floc TSS


0

50

P L S E M P L S E M P L S E M P L S E M P L S E M P L S E M P L S E M

Land resource Fossil fuels Metal ores Minerals Nuclear energy Water resources Abiotic renewable

resources

MJ e

x,C

EEN

E

Pil

ot S M

Electricity consumption - stirring pumps Electricity consumption - other pumps

Electricity consumption - flue gas blower Heating of the pond

Direct Land occupation Infrastructure

Direct phosphorus emissions to water Direct nitrogen emissions to water


Resource footprint (CEENE results)

50

100

150

200

250

300

350

400

450

ex

,CEEN

Ek

g-1

Ma

B-f

loc T

SS

50

100

150

200

250

300

350

400

450

ex,C

EEN

Ek

g-1

Ma

B-f

loc

TS

S

-69%

-77%

Total CEENE plant L: 278 MJ kg-1 MaB-floc TSS


0

50



resources

MJ e

x,C

EEN

E

0

50



resources

MJ e

x,C

EEN

E

Pil

ot S M






IPCC 2007 - Climate changeRe CiPe 2013 - Marine

eutrophication

Re CiPe 2013 - Freshwater

eutrophication

4,E-03

6,E-03

8,E-03

1,E-02

1,E-02

1,E-02

kg

-1M

aB

-flo

c T

SS

4,E-03

6,E-03

8,E-03

1,E-02

1,E-02

1,E-02

2,E-02

-1 M

aB

-flo

c T

SS

10

15

20

25

30

eq

kg

-1M

aB

-flo

c T

SS

4,E-03

6,E-03

8,E-03

1,E-02

1,E-02

1,E-02

kg

-1M

aB

-flo

c T

SS

4,E-03

6,E-03

8,E-03

1,E-02

1,E-02

1,E-02

2,E-02

-1 M

aB

-flo

c T

SS

10

15

20

25

30

eq

kg

-1M

aB

-flo

c T

SS

67% 85% 91% 28% 34% 36% 67% 90% 97% 75%


Pil

ot S M





0,E+00

2,E-03

4,E-03

Pilot L S E

kg

Pe

qk

g

0,E+00

2,E-03

4,E-03

Pilot L S E

kg

Ne

qk

g-

0

5

Pilot L S E M

kg

CO

2 e

q k

g

0,E+00

2,E-03

4,E-03

Pilot L S E

kg

Pe

qk

g

0,E+00

2,E-03

4,E-03

Pilot L S E

kg

Ne

qk

g-

0

5

Pilot L S E M

kg

CO

2 e

q k

g

LCA results: environmental sustainability of the Integrated systems

Backwash

wastewater

Backwash

wastewater

Backwash supernatant released in the sewage system


HeatPikeperch

RAS

Fish sludge

Settling

Maize silageSoil conditioner


Valorisation as shrimp feed

Shrimp feed

Drying

Baseline scenario

Raceway ponds

MaB-floc liquor Dewatering

Heat

Biogas

Electricity to the grid

Scenario 1 - valorisation of MaB-flocs as shrimp feed

Pikeperch RAS Settling Milling

Digester CHP


Valorisation as biogas

Soil conditioner

MaB-floc liquor

Backwash

wastewater

Heat

Heat


HeatFish sludge

DigesterMaize silage

Soil conditioner


Fish sludge

Maize silage

Digester Biogas

DigestateRaceway

ponds Dewatering

CHP

CHPBiogas Electricity to the grid

Electricityto the grid

Scenario 2 - valorisation of MaB-flocs as biogas

Pikeperch RAS Settling


Resource footprint1

- 133%- 101%


Left bar: Right bar:

Avoided processes

1 CEENE results without abiotic renewable resources


Freshwater eutrophication

(ReCiPe 2013)

Marine eutrophication

(ReCiPe 2013)

Carbon footprint(IPCC 2007)


Left bar: Right bar:

Avoided processes

ConclusionMaB-floc technology: stirring has the highest contribution to most impact categories

Integrated aquaculture waste treatment system:• Potential to compete with the baseline scenario and contribute to a

sustainable connection of the water-food-energy nexus in the aquaculture sector


• Valorizing MaB-flocs into shrimp feed: overall more sustainable than into biogas

Future research:• Improvement of LCA with more complete data on nutrient cycle

(measurements needed)

• Focus on the improvement of the energy efficiency of the system, rather than of MaB-flocs productivity

Bottleneck: EU legislation

Thank you!

[email protected]

+32 (0) 9 264 99 27


+32 (0) 9 264 99 27

Documents

Environmental Sustainability Assessment of a Microalgae ... · Heat Soil conditioner 2 MaB-flocs plants are integrated: Plant L (linearly up-scaled plant) Plant SEM (plant L with