Avnimelech
Bio-flocs: Formation, properties, management
Yoram Avnimelech Technion, Israel Inst. Of Technology [email protected]
Control of Water Quality • We know how to use heterotrophic bacteria to control water quality: • With zero or limited water exchange we get dense population. • Aeration and mixing provide excellent conditions for microbial activity and metabolism of organic wastes. • By using C/N control, we can easily, consistently and quantitatively reduce concentrations of ammonia and nitrite in the water.
Feeding with Bacteria • Shrimp and fish (tilapia, other) can harvest the bacteria and essentially, double protein utilization. • However, harvest efficiency depends on presence of flocs and seems to improve with bio-flocs size. • Bio-floc formation and properties are still empirical and un-predictable.
.
Typically, ponds start as green autotrophic systems only later on in the season Microbial community develops, the pond turns brown and flocs become visible This sequence is empirical and as yet, no guidelines toward the optimal management of microbial flocs is available. The goal of the present work is To develop the needed control Technology toward an optimal Bio-flocs development.
15 N in Fish
0.38200
C/N = 23 0.38000
0.37800
C/N = 15
% 15N
0.37600
C/N = 9
0.37400
0.37200
0.37000
0.36800 0
2
4
6
8
10
12
14
16
Day
More efficient uptake in C/N = 23 Steady state (uptake = excretion) with time
18
Uptake of protein from flocs, using 15N tagging, Dor, Israel, 2005 Daily Specific C/N TSS, 15N in Daily N mg/l fish (*) Uptake protein uptake (**) mg/kg uptake fish mg/kg 9.2 441 0.3722 28.0 180 0.063 15
450 0.3725
29.2
188
0.065
23
484
52.4
338
0.108
*15N(t=0) 0.3689
0.379
** Daily N Uptake/TSS
Floc Volume vs Time
Floc Volume 180 (ml/l) 160
y = 13.795x + 14.789 R2 = 0.8834
C/N = 23
140
FV, ml
120
100
C/N =9.2 C/N = 15 C/N = 23
80 y = 4.4337x + 13.476 2
R = 0.6256
60
C/N = 15
40 y = 4.2x + 15 2
R = 0.6509
20
C/N = 9.2
0 0
2
4
6
8
Days
Higher floc volume (same TSS) in C/N =23
10
12
Uptake = K * Suspended Solids ( K
K = Specific uptake =
Uptake of protein from flocs, using 15N tagging, Dor, Israel, 2005 Daily Specific C/N TSS, 15N in Daily N mg/l fish (*) Uptake protein uptake (**) mg/kg uptake fish mg/kg 9.2 441 0.3722 28.0 180 0.063 15
450 0.3725
29.2
188
0.065
23
484
52.4
338
0.108
*15N(t=0) 0.3689
0.379
** Daily N Uptake/TSS
Size of flocs seems to be very important
Clay (mud) addition may help bio-flocs formation Seeding of Flocs
100 90
y = 17.464x + 1.6339
80
R = 0.9992
2
F lo c v o lu m e , m l/l
Bentonite 70
y = 10.714x + 1.2589
60
R = 0.991
2
Bran
50 40 30
y = 9.8929x + 1.6518
20
2
R = 0.9972 Control
10 0 0
1
2
3 Days
4
5
6
Adding suitable inoculum may help to form bio-flocs, possibly large ones
Effect of Inoculum 70 flo c v o lu m e (m l)
60 50 40 30
no inoculum
20
100 mg C
10
2150 mg C 3
4
4
5
5 days
6
6
7
7
High C/N seems to enhance larger flocs 120
flo c v o l (m l)
100 80 C/N 9.2
60
C/N 23
40 20 0 9/11/05 14/11/0 19/11/0 24/11/0 29/11/0 4/12/05 9/12/05 14/12/0 5 5 5 5 5 Date
C/N ratio may affect floc composition in the beginning. Possibly, later, a steady- state composition is achieved
3/2006
C/N 9 C/N 15
14
C/N 23
C /N s u s
12 10 8
stop feeding
6 4
6
8
10
12
14 days
16
18
20
22
Carbon percentage in the suspended bio-flocs was nor affected d C/N ratio. On the average, 29% organic C By the feed y = 0.2955x + 31.731 R2 = 0.8079
sus C ver TSS
y = 0.2859x + 28.232 R2 = 0.8514 CN =9
300.0 250.0
S us C
200.0
C/N =9 C/N = 23
150.0
Linear (C/N =9)
100.0
Linear (C/N = 23)
50.0 0.0 0
200
400 TSS
600
800
C/N in flocs not depended on C/N in feed y = 0.1577x - 1.4364
y = 0.1511x + 2.1491 2 R = 0.7112 C/N 9
Sus N ver Sus C
2
R = 0.7386 45.00 40.00 35.00 Sus N
30.00
CN=9 CN = 23
25.00 20.00 15.00 10.00 5.00 0.00 0.0
50.0
100.0
150.0
200.0
250.0
300.0
Sus C
So, where is the nitrogen???
C/N 9
3/2006
C/N 15 C/N 23
N O 3 + 2 - N ( m g /l)
80 60 40
stop feeding
20 0 4
6
8
10
12
14 days
16
18
20
22
In case of C/N = 23 ALL N is used to generate microbial protein. With lower C/N in feed, excessive N is released C/N 9
3/2006
C/N 15
N H 4 - N ( m g /l)
30
C/N 23
20 10 stop feeding
0 4
6
8
10
12
14 days
16
18
20
22
Some conclusions • 1. We need to learn more on bio-flocs control. We present here preliminary results. • 2. C/N, seeding with clay, inoculum, all affect floc formation and properties. • 3. It seems, that regardless of C/N in feed, bio-flocs composition approaches a steady composition.
Thanks Commercial break: This presentation with others Will be displayed In the Bio-flocs technology Web site: http://floc.aesweb.org/ You are welcome to visit
Yoram Avnimelech Technion, Israel Inst. Of Technology [email protected]
Control of Water Quality • We know how to use heterotrophic bacteria to control water quality: • With zero or limited water exchange we get dense population. • Aeration and mixing provide excellent conditions for microbial activity and metabolism of organic wastes. • By using C/N control, we can easily, consistently and quantitatively reduce concentrations of ammonia and nitrite in the water.
Feeding with Bacteria • Shrimp and fish (tilapia, other) can harvest the bacteria and essentially, double protein utilization. • However, harvest efficiency depends on presence of flocs and seems to improve with bio-flocs size. • Bio-floc formation and properties are still empirical and un-predictable.
.
Typically, ponds start as green autotrophic systems only later on in the season Microbial community develops, the pond turns brown and flocs become visible This sequence is empirical and as yet, no guidelines toward the optimal management of microbial flocs is available. The goal of the present work is To develop the needed control Technology toward an optimal Bio-flocs development.
15 N in Fish
0.38200
C/N = 23 0.38000
0.37800
C/N = 15
% 15N
0.37600
C/N = 9
0.37400
0.37200
0.37000
0.36800 0
2
4
6
8
10
12
14
16
Day
More efficient uptake in C/N = 23 Steady state (uptake = excretion) with time
18
Uptake of protein from flocs, using 15N tagging, Dor, Israel, 2005 Daily Specific C/N TSS, 15N in Daily N mg/l fish (*) Uptake protein uptake (**) mg/kg uptake fish mg/kg 9.2 441 0.3722 28.0 180 0.063 15
450 0.3725
29.2
188
0.065
23
484
52.4
338
0.108
*15N(t=0) 0.3689
0.379
** Daily N Uptake/TSS
Floc Volume vs Time
Floc Volume 180 (ml/l) 160
y = 13.795x + 14.789 R2 = 0.8834
C/N = 23
140
FV, ml
120
100
C/N =9.2 C/N = 15 C/N = 23
80 y = 4.4337x + 13.476 2
R = 0.6256
60
C/N = 15
40 y = 4.2x + 15 2
R = 0.6509
20
C/N = 9.2
0 0
2
4
6
8
Days
Higher floc volume (same TSS) in C/N =23
10
12
Uptake = K * Suspended Solids ( K
K = Specific uptake =
Uptake of protein from flocs, using 15N tagging, Dor, Israel, 2005 Daily Specific C/N TSS, 15N in Daily N mg/l fish (*) Uptake protein uptake (**) mg/kg uptake fish mg/kg 9.2 441 0.3722 28.0 180 0.063 15
450 0.3725
29.2
188
0.065
23
484
52.4
338
0.108
*15N(t=0) 0.3689
0.379
** Daily N Uptake/TSS
Size of flocs seems to be very important
Clay (mud) addition may help bio-flocs formation Seeding of Flocs
100 90
y = 17.464x + 1.6339
80
R = 0.9992
2
F lo c v o lu m e , m l/l
Bentonite 70
y = 10.714x + 1.2589
60
R = 0.991
2
Bran
50 40 30
y = 9.8929x + 1.6518
20
2
R = 0.9972 Control
10 0 0
1
2
3 Days
4
5
6
Adding suitable inoculum may help to form bio-flocs, possibly large ones
Effect of Inoculum 70 flo c v o lu m e (m l)
60 50 40 30
no inoculum
20
100 mg C
10
2150 mg C 3
4
4
5
5 days
6
6
7
7
High C/N seems to enhance larger flocs 120
flo c v o l (m l)
100 80 C/N 9.2
60
C/N 23
40 20 0 9/11/05 14/11/0 19/11/0 24/11/0 29/11/0 4/12/05 9/12/05 14/12/0 5 5 5 5 5 Date
C/N ratio may affect floc composition in the beginning. Possibly, later, a steady- state composition is achieved
3/2006
C/N 9 C/N 15
14
C/N 23
C /N s u s
12 10 8
stop feeding
6 4
6
8
10
12
14 days
16
18
20
22
Carbon percentage in the suspended bio-flocs was nor affected d C/N ratio. On the average, 29% organic C By the feed y = 0.2955x + 31.731 R2 = 0.8079
sus C ver TSS
y = 0.2859x + 28.232 R2 = 0.8514 CN =9
300.0 250.0
S us C
200.0
C/N =9 C/N = 23
150.0
Linear (C/N =9)
100.0
Linear (C/N = 23)
50.0 0.0 0
200
400 TSS
600
800
C/N in flocs not depended on C/N in feed y = 0.1577x - 1.4364
y = 0.1511x + 2.1491 2 R = 0.7112 C/N 9
Sus N ver Sus C
2
R = 0.7386 45.00 40.00 35.00 Sus N
30.00
CN=9 CN = 23
25.00 20.00 15.00 10.00 5.00 0.00 0.0
50.0
100.0
150.0
200.0
250.0
300.0
Sus C
So, where is the nitrogen???
C/N 9
3/2006
C/N 15 C/N 23
N O 3 + 2 - N ( m g /l)
80 60 40
stop feeding
20 0 4
6
8
10
12
14 days
16
18
20
22
In case of C/N = 23 ALL N is used to generate microbial protein. With lower C/N in feed, excessive N is released C/N 9
3/2006
C/N 15
N H 4 - N ( m g /l)
30
C/N 23
20 10 stop feeding
0 4
6
8
10
12
14 days
16
18
20
22
Some conclusions • 1. We need to learn more on bio-flocs control. We present here preliminary results. • 2. C/N, seeding with clay, inoculum, all affect floc formation and properties. • 3. It seems, that regardless of C/N in feed, bio-flocs composition approaches a steady composition.
Thanks Commercial break: This presentation with others Will be displayed In the Bio-flocs technology Web site: http://floc.aesweb.org/ You are welcome to visit
