“Biofiltration of Prawn Farm Effluent by Oysters and Macroalgae” Adrian Jones 1, Nigel Preston 2 & William Dennison 1 1 Marine Botany, Botany Department,

““Biofiltration of Prawn Biofiltration of Prawn Farm Effluent by Farm Effluent by

Oysters and Oysters and Macroalgae”Macroalgae”

Adrian JonesAdrian Jones11, Nigel Preston, Nigel Preston22 & William Dennison & William Dennison11

C S I R OAUSTRALIA

1 1 Marine Botany, Botany Department, The University of QueenslandMarine Botany, Botany Department, The University of Queensland22 CSIRO Marine Research, Cleveland, Queensland CSIRO Marine Research, Cleveland, Queensland

Research funded by the Research funded by the Fisheries Research and Development CorporationFisheries Research and Development Corporation

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Need for ResearchNeed for Research

• Recapture nutrients from the high cost feed Recapture nutrients from the high cost feed pellets which are not converted into prawn pellets which are not converted into prawn biomass.biomass.

• Prawn farm effluent contains elevated Prawn farm effluent contains elevated concentrations of:concentrations of:– bacteriabacteria

– phytoplanktonphytoplankton

– nutrientsnutrients

– suspended solidssuspended solids

• Sewage treatment techniques are often Sewage treatment techniques are often ineffective due to:ineffective due to:– low specific gravity of particleslow specific gravity of particles

– high volume high volume

– high salt contenthigh salt content

– prohibitively expensive.prohibitively expensive.

• To develop a system of long term sustainable To develop a system of long term sustainable aquaculture.aquaculture.

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Need for ResearchNeed for Research

~ 100 - 600 mg l~ 100 - 600 mg l

WaterWaterQualityQualityParameterParameter

PrawnPrawnEffluentEffluent

Oceanic Oceanic WaterWater

TSSTSS-1-1

< 2 mg l< 2 mg l-1-1

Chlorophyll Chlorophyll aa ~ 20 - 200 µg l~ 20 - 200 µg l -1-1< 1 µg l< 1 µg l

-1-1

Total NitrogenTotal Nitrogen ~200 µM~200 µM~1 µM~1 µM

Total PhosphorusTotal Phosphorus ~20 µM~20 µM~0.1 µM~0.1 µM

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ExperimentalExperimentalDesignDesign

Wat

er I

nfl

owW

ater

In

flow

InflowInflow

OutflowOutflow

25cm25cm

60cm60cm

40cm40cm

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Hig

hH

igh

Hig

hH

igh

Hig

hH

igh

Med

ium

Med

ium

Med

ium

Med

ium

Med

ium

Med

ium

Low

Low

Low

Low

Low

Low

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UnsettledUnsettled

0

5000000

10000000

15000000

20000000

25000000

30000000

Inflow Control Control High Medium Low

Treatment

Bac

teri

a (p

er m

l)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14


Treatment

TSS

(g

l-1)

0

10

20

30

40

50

60


Treatment

Chl

orop

hyll

a (µ

g l

-1)

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UnsettledUnsettled

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2


Treatment

Tot

al P

hosp

horu

s (m

g l-1

)

0

0.4

0.8

1.2

1.6

2


Treatment

Tot

al N

itro

gen

(mg

l-1)

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PrawnPrawnPondsPonds

RacewaysRaceways

RecirculatingRecirculatingTankTank

MoretonMoretonBayBay

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RecirculatedRecirculated

12%19%

33%

54%

09:00 11:00 13:00 15:000

5

10

15

20

25

30

No.

of

Bac

teri

a pe

r m

l (x

10 )

Sampling Time

Inflow Outflow

6B

acte

ria

per m

l x 1

06

54%

09:00 11:00 13:00 15:000

5

10

15

20

25

30

Chl

conc

entr

atio

n (

g/

L)

Sampling Time

Inflow Outflow

115%

20%

4%20%a

C

hlor

ophy

ll a

(µ

g l-1

)

54%

09:00 11:00 13:00 15:000

0.04

0.08

0.12

0.16

Tot

al S

uspe

nded

Sol

ids

(g. l

-1)

Sampling Time

118%

63%

32%19%

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Oyster Growth

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Raby Bay MBPF Moreton Bay

Site

TSS

(g

l-1)

0

0.2

0.4

0.6

0.8


Site

Chl

orop

hyll

a (µ

g l-1

)

0

0.1

0.2

0.3

0.4

0.5


Site

Mea

n G

row

th (

dry

wt)

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SummarySummary

• Recirculating produced greater Recirculating produced greater improvements in water qualityimprovements in water quality

• However tests on oyster growth However tests on oyster growth rate demonstrated inhibition with rate demonstrated inhibition with the effluentthe effluent

• Macroalgae were also affected by Macroalgae were also affected by the high sediment loadsthe high sediment loads

• We then tested an integrated We then tested an integrated system which employed pre-system which employed pre-settling and also nutrient settling and also nutrient assimilation by macroalgae assimilation by macroalgae

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Filter FeedingFilter Feeding

• Oysters filter bacteria and phytoplankton Oysters filter bacteria and phytoplankton and convert them to meat.and convert them to meat.

• Oysters filter inorganic material and pellet Oysters filter inorganic material and pellet smaller particles into larger pseudofaeces smaller particles into larger pseudofaeces which can settle out of suspension.which can settle out of suspension.

AnusAnusHeartHeart

IntestineIntestine

StomachStomach

MantleMantleGillsGills

Adductor Adductor MuscleMuscle

Style SacStyle Sac Labial Palps Labial Palps (mouth)(mouth)

HingeHinge

Faeces (organic) and Faeces (organic) and AmmoniaAmmoniaPseudofaeces (inorganic)Pseudofaeces (inorganic)

BacteriaBacteriaPhytoplanktonPhytoplanktonInorganic particlesInorganic particlesDetritusDetritus

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Suspended SolidsSuspended Solids

Particle SizeParticle Size

2.282 3.535 5.477 8.485 13.15 20.37 3.1552.282 3.535 5.477 8.485 13.15 20.37 3.155

00

50005000

1000010000

1500015000

2000020000

2500025000

3000030000

3500035000

Nu

mb

er o

f P

arti

cles

Nu

mb

er o

f P

arti

cles

Control InflowControl Inflow

Oyster InflowOyster Inflow

Control OutflowControl Outflow

Oyster OutflowOyster Outflow

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EffluentEffluent24 Hours24 HoursSettlingSettling

0 hrs0 hrs

24 hrs24 hrs

24 hrs24 hrs

48 hrs48 hrs

48 hrs48 hrs

72 hrs72 hrs

ShellsShells(Control)(Control)

OystersOysters(Rep A)(Rep A)

OystersOysters(Rep B)(Rep B)

OystersOysters(Rep C)(Rep C)

No AlgaeNo Algae(Control)(Control)

AlgaeAlgae(Rep A)(Rep A)

AlgaeAlgae(Rep B)(Rep B)

AlgaeAlgae(Rep C)(Rep C)

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SettledSettled

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70 80

Time (h)

Tur

bidi

ty (

NT

U)

Macroalgae Oysters Control

0

20

40

60

80

100

120

140

160

180

0 10 20 30 40 50 60

Time (h)

Fluo

resc

ence

Oysters Control

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SettledSettled

0

0.1

0.2

0.3

0.4

Settling Control Oysters

Treatment

Sedi

men

t (g

l-1)

0

10

20

30

40

50

60

Initial Settled Oysters Macroalgae

Treatment

TSS

(Per

cent

Org

anic

)

Control Oysters Macroalgae

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SettledSettled

0

100

200

300

400

0 20 40 60 80Time (h)

Tot

al N

itro

gen

(µM

)


0

5

10

15

20

25

0 20 40 60 80

Time (h)

Tot

al P

hosp

horu

s (µ

M)


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0102030405060

0 20 40 60 80

Time (h)

Am

mon

ium

(µM

)


SettledSettled

0

1

2

3

4

0 20 40 60 80

Time (h)

Pho

spha

te (

µM)


0

5

10

15

0 20 40 60 80

Time (h)

Nit

rate

/ N

itri

te (

µM)


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Data SynthesisData Synthesis

UnsettledUnsettled RecirculatedRecirculated SettledSettled

BacteriaBacteria 5656 1212 ndnd

TSSTSS 5050 1919 1.51.5

Chl Chl aa 1111 44 0.750.75

Total NTotal N 7878 ndnd 2525

Total PTotal P 6767 ndnd 1414

NHNH44++ ndnd ndnd 9090

NONO33-- ndnd ndnd 2828

POPO443-3- ndnd ndnd 3535

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SummarySummary

• Assimilation of nutrients by organisms can Assimilation of nutrients by organisms can take place naturally or by employing take place naturally or by employing biological filtering systems.biological filtering systems.

• These organisms are capable of reducing These organisms are capable of reducing the concentrations of:the concentrations of:

– water column nutrient (particulate and water column nutrient (particulate and dissolved)dissolved)

– phytoplanktonphytoplankton

– bacteriabacteria

– suspended solids (especially the small suspended solids (especially the small unsettleable inorganic particles)unsettleable inorganic particles)

• Sedimentation is necessary to ensure the Sedimentation is necessary to ensure the efficiency and health of the biofilters efficiency and health of the biofilters

Documents

“Biofiltration of Prawn Farm Effluent by Oysters and Macroalgae” Adrian Jones 1, Nigel Preston 2 & William Dennison 1 1 Marine Botany, Botany Department,