““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
C S I R OAUSTRALIA
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.
C S I R OAUSTRALIA
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
C S I R OAUSTRALIA
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
Inflow Control Control High Medium Low
Treatment
TSS
(g
l-1)
0
10
20
30
40
50
60
Inflow Control Control High Medium Low
Treatment
Chl
orop
hyll
a (µ
g l
-1)
C S I R OAUSTRALIA
UnsettledUnsettled
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Inflow Control Control High Medium Low
Treatment
Tot
al P
hosp
horu
s (m
g l-1
)
0
0.4
0.8
1.2
1.6
2
Inflow Control Control High Medium Low
Treatment
Tot
al N
itro
gen
(mg
l-1)
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ExperimentalExperimentalDesignDesign
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%
C S I R OAUSTRALIA
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
Raby Bay MBPF Moreton Bay
Site
Chl
orop
hyll
a (µ
g l-1
)
0
0.1
0.2
0.3
0.4
0.5
Raby Bay MBPF Moreton Bay
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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ExperimentalExperimentalDesignDesign
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
)
Macroalgae Oysters Control
0
5
10
15
20
25
0 20 40 60 80
Time (h)
Tot
al P
hosp
horu
s (µ
M)
Macroalgae Oysters Control
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0102030405060
0 20 40 60 80
Time (h)
Am
mon
ium
(µM
)
Macroalgae Oysters Control
SettledSettled
0
1
2
3
4
0 20 40 60 80
Time (h)
Pho
spha
te (
µM)
Macroalgae Oysters Control
0
5
10
15
0 20 40 60 80
Time (h)
Nit
rate
/ N
itri
te (
µM)
Macroalgae Oysters Control
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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
C S I R OAUSTRALIA
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