Transcript Biological Filtration

Biological Filtration
Hugh S. Hammer, PhD GSCC
David Cline, ACES
Ron Malone, PhD LSU
Biological Filtration
NH3
Ammonia
B1
NO2
Nitirite
B2
NO3
Nitrate
Ammonia
Sources
 Decomposition of
uneaten feed
 Decomposition of fecal
materials
 Decomposition of dead
materials
 By product of protein
(feed) metabolism
Ammonia Exists in 2 Forms
NH3
 Toxic
 More at High Temp
 More at High pH
NH4
+
 Less Toxic
 More at Low Temp
 More at Low pH
+
NH4
NH3 <->
Equilibrium
Bacteria of Reaction #1
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Nitrosomonas sp.
Nitrosospira sp.
Nitrosolobus sp.
Nitrosovibrio sp.
Nitrosococcus sp.
Oxidation
NH3/NH4
+
NO2
Chemistry of Reaction #1
 Requires Oxygen
 Results in decreasing (more acidic) pH
 Requires 7 grams of alkalinity (CO3-2)
for each gram of ammonia (NH3)
converted to nitrate (NO3)
pH - What Should It Be
Alkalinity (Carbonate CO3-)
 Stabilizes pH around pH 7-8
 Resists changes in pH (acts
as a buffer)
 Required by nitrifying
bacteria as a carbon source
for survival
Biological Filtration Reaction #2
NH3
Ammonia
B1
NO2
Nitrite
B2
NO3
Nitrate
Nitrite Conversion to Nitrate
 Requires oxygen
 Does not change pH
 Requires alkalinity
Bacteria of Reaction #2
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Nitrobacter sp.
Nitrospira sp.
Nitrospina sp.
Nitrococcus sp.
Oxidation
NO2
NO3
What About Nitrate?
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Non toxic in most fish up to 300 ppm
Easily solved via water change
Also managed through addition of plants
Can be toxic for many invertebrates (i.e.
shrimps)
NH3
Ammonia
B1
NO2
Nitrite
B2
NO3
Nitrate
Biofiltration
TS S
BO D
H e te ro t ro p h ci
B a c te r ai
TAN
+
N H3 + N H
4
(T o ta lAm m o n ai )
O2
H CO
3
N it ro s om o n a s s p .
CO
N itr ifci a toi n
N O2
N
( it r ite )
O
H CO
3
2
2
N it ro b a c te r s p .
CO
NO
3
N
( it ra te )
2
Optimal Nitrification Conditions
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pH 7.5
High Dissolved Oxygen
Alkalinity CO3- (Carbon Source)
Surface Area (Media)
Food (ammonia and nitrite)
Low Light (Light inhibits growth)
Ammonia oxidizing bacteria grow fast
Nitrite oxidizing bacteria grow slowly
How Can You Tell
If Your Filter Is Working ?
Filter Media
Bead Filters and Drop Filters
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Probably the industry standard
Both mechanical and biological filtration
A type of fluidized bed filter
Space saving (consolidated approach)
Can be expensive
Drop filters are great for saving water, they
concentrate solids
 Drop filters don’t clog easily
Biofiltration
H e te ro tro ph ci B oi fmil
O x ygen
O rg a n ci W a s te s
BO D
D e ca y
C a rb o n D oi x di e
Amm on ai
P al s tci
B ead
O x ygen
B ci a rb on a te s
N itr ite
C a rb o n D oi x di e
N itra te
Em b ed d ed N itr ify ni g
B a c te r ai
N itr if ci a t oi n
Propeller-washed Floating Bead Filters
F iltra toi n
B a ckw a sh ni g
Filter Mode
(2 )
W a te r F low
Drop Filters :
Low Water Loss
Floating Bead Bioclarifiers
A
B
(1 )
W a te r F low
(7 )
(5 )
(6 )
C
E
(4 )
A ir F low
A ir
W a te r
Settled Backwash
Waters returned to
system
D
Air Bleed
Builds Charge
W a te r
S lu d g e
P a ten t # 5 7, 70 0, 80
(3 )
Backwash
mode
(2 )
Drop Filters : Low Water
Loss
Floating Bead Bioclarifiers
Released Air Washes Beads
(1 )
W a te r F low
(7 )
(5 )
(6 )
C
E
(4 )
A ir F low
A ir
W a te r
Internal Sludge
Capture
P a ten t # 5 7, 70 0, 80
(3 )
Circulation
Aeration
Degassing
Solids Capture
Biofiltration
Inlet
Airlift
Fluidized Bed Filters
 Can use any type of media (sand and beads
are most common)
 Uses a mixing media/water matrix
 Great biological filtration
 Bead filters are a type of fluidized filter that
also accomplish solids capture.
 Also called submerged filters when large
void volume media is used.
Foam Block Media
Active Media
Fluidized Sand Bed Filters
 THESE ARE NOT RAPID SAND FILTERS
 Advantages:
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Tremendous surface area (the most)
Nitrite eating bacteria grow great
Best biological filters
Huge biological loads
Aquarium industry gold standard
 Disadvantages:
– Heavy, may require multiple pumps during power
outages
– Bacteria die quickly from O2 deprivation during power
outages
– MUST have all of the solids out of the water (solids can
cause serious problems with channeling)
Trickle Filters, Packed Towers,
Bio-wheels, RBCs
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Media is not continually submerged but moist
Efficiency depends on water distribution
Inexpensive to build
Good biological filtration
Not good for solids removal (hard to clean)
Great for aerating water and stripping carbon dioxide
Will change the temperature of water (cools it off,
sometimes good and sometimes not)
 Some RBCs are very expensive but are great
biofilters
Packed Tower
 Adds Oxygen
 Removes Carbon
Dioxide
 Biological
Filtration
 Easy to construct
Trickle Filter
Wet Dry Filters
 Screen + Trickle Filter
+ Fluidized Bed Filter =
Wet Dry Filter
 Consolidated approach
 Good for small loads
(aquariums)
 Advantages and
Disadvantages of all
the components