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Biological process controlby visual index
SAMNEUNG CONSTRUCTIONS CO.,LTD
SEP. 2003
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visual test for operation
Sludge volume index(SVI)
Definition : this is a index of settlement of activated sludge
The range of good settlement (SVI) is 80 to 120
Test method : 1) test SV30 (%). 2) test MLSS
Calculation : SVI(mg/L) = [SV30(%) / MLSS(mg/L)] x 10000
If SVI is above 120mg/L, the activated sludge may be bulking sludge.
SV30(%) test method :
read sludge volume at 30
minute since started settling
fill up to 1 L point line with
the wastewater taken out of
last aeration pond
Setting for 30 minutePrepare I L mess cylinder
Biological unit operationsOperation maintenance manual
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1. Loading Criteria. the food-to-microorganism ratio (F/M)
F/M = V XSoQ------ --
whereF/M = food-to-microorganism ratio, d-1So = influent BOD or COD concentration, mg/LQ = influent wastewater flow rate, m3/dV = aeration tank volume, m3
X = concentration of volatile suspended solids(MLVSS) in the aeration tank, mg/L
Normal operation range of F/M is 0.1-0.4.Design F/M ratio including the sludge attached to media is 0.35. But F/M ratio excluding the attached biosludge isabout 0.2. operators should find out how much optimum F/M ratio is in case of their hospital because the F/M ratiois different according to wastewater characters.
Return sludge flow rate
Above F/M formula, F/M can be controlled by X because So, andQ are usually constant, and V is fixed.X is also controlled by the return sludge as shown in next formula.
X = Q + QRXR QR
------- QR= XR- XXQ
-------or--(1) ---(2) QR/Q = XR- XX
------- ---(3)
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ExampleMLSS is 2500mg/L in laboratory test.Influent BOD5 is 200mg/L. influent flow rate is 200 m3/day. Te volume of aeration basin(FBBR) is 50 m3.Calculate F/M ratio.
SolutionF/M = V X
SoQ
------ -- = 300 m3 x 3000mg/L
200mg/L x 100m3/day
------ -- ------------------------------- = 50 m3 x 2500mg/L
200mg/L x 100m3/day
------ -- -------------------------- =
= 0.16
whereX = concentration of volatile suspended solids(MLVSS) in the aeration tank, mg/LXR = concentration of return sludge, mg/L
The concentration of return sludge is 8000-10000mg/L in normal operationcondition.QR = return sludge flow rate, m3/dQ = influent wastewater flow rate, m3/dAbove formula (1), if Q is constant, X is controlled by return sludgeReturn sludge can be calculated by formula (2).The ratio of QR/Q is usually 30 50 %
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Sludge retention time (SRT)SRT = Qw Xw+ Qe Xe
V X------------
WhereSRT = mean cell-residence time based on the aeration tank volume, dV= aeration tank volume, m3X= concentration of volatile suspended solid in the aeration tank, mg/LQw= waste sludge flow rate, m3/dXw= concentration of volatile suspended solids in the waste sludge, mg/LQe= treated effluent flow rate, m3/dXe= concentration of volatile suspended solids in the treated effluent, mg/LNormal operation range of SRT is 3-4,
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settling test with cylinder
Biological unit operationsOperation maintenance manual
A
No full growth of
sludge
B
Small size dispersed
floc
After 30mine
C
Rising sludge
by nitrification:
no settling again after patting cylinder
with wood bar
DRising sludge
by over aeration:
resettling again after patting cylinder
with wood bar
Sludge rising after
30mine
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M
Bulking by high viscosity
matters
High turbidity
J
deflocculation
L
Bulking sludge by mold,
yeast,
No settle. Ph: 5-6,
mold,
yeast
K
Bulking sludge by
filamentous bacteria
No settle. Ph: 6-8
N
Bulking by
zoogloea
E
Rising sludge by spoilage
sludge
H
Pin floc
I
Over oxidized sludge by
high DO
brown
colorfoam
F
Rising sludge
by fungi
floated oil
G
Rising sludge
by oil
Very small size
floc
No clean
A little
clean
Small
sludge
Sludge color is dark
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Control process by visual index
Bulking sludge byfilamentous bacteria.
SV30 is high
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Control process by visual index
Normal operation state
in bioreactor.
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Control process by visual index
Foaming by surfactant
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Control process by visual index
Forming by
nondegradable mattersin buffer basin.
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Control process by visual index
Forming by
nonbiodegradablematters in bio reactor.
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Control process by visual index
Foaming bysurfactant`
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Control process by visual index
Foaming by high
concentration protein inbuffer basin
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Control process by visual index
Foaming by highconcentration
protein in bioreactor
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Control process by visual index
Foaming by highconcentration
suspended solids in bioreactor
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Control process by visual index
Foaming by fungi in bioreactor
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Control process by visual index
Foaming by fungi plus
fat oil in bio reactor
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Control process by visual index
Foaming by fungi when
aeration was stopped inbio reactor
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Control process by visual index
Foaming by fungi in V-NOTCH
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Control process by visual index
Foaming in returnsludge line
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Control process by visual index
Foaming by fungi in
bio reactor. The foamis overflowing frombio reactor
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Control process by visual index
Foaming by fungi.Turbidity is very low.
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Control process by visual index
Foaming by fungi in
bio reactor. The formcover all surface of bioreactor
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Control process by visual index
Foaming by fungi or
Thiothrix in bioreactor.
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Control process by visual index
Foaming by fungi or
Thiothrix. The sludgedidnt be settled after24 hours
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Control process by visual index
Foaming by fungi orThiothrix. The sludge
didnt be settled after
24 hours. Scum is darkcolor.
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Control process by visual index
Foaming by high
viscosity matters
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Control process by visual index
The sludge can notmake bio flocculationby cause of high F/M
ratio in bio reactor
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Control process by visual index
The sludge wasbroken by cause of
high DO and low F/Mratio in bio reactor
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Control process by visual index
The sludge wasfloated to thesurface of settling
basin by cause ofdenitrification.