bioprocess visual index

8/13/2019 Bioprocess Visual Index

1/31

Biological process controlby visual index

SAMNEUNG CONSTRUCTIONS CO.,LTD

SEP. 2003


2/31

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


3/31

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)


4/31

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 %


5/31

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,


6/31

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


7/31

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


8/31

Control process by visual index

Bulking sludge byfilamentous bacteria.

SV30 is high


9/31


Normal operation state

in bioreactor.


10/31


Foaming by surfactant


11/31


Forming by

nondegradable mattersin buffer basin.


12/31


Forming by

nonbiodegradablematters in bio reactor.


13/31


Foaming bysurfactant`


14/31


Foaming by high

concentration protein inbuffer basin


15/31


Foaming by highconcentration

protein in bioreactor


16/31


Foaming by highconcentration

suspended solids in bioreactor


17/31


Foaming by fungi in bioreactor


18/31


Foaming by fungi plus

fat oil in bio reactor


19/31


Foaming by fungi when

aeration was stopped inbio reactor


20/31


Foaming by fungi in V-NOTCH


21/31


Foaming in returnsludge line


22/31


Foaming by fungi in

bio reactor. The foamis overflowing frombio reactor


23/31


Foaming by fungi.Turbidity is very low.


24/31


Foaming by fungi in

bio reactor. The formcover all surface of bioreactor


25/31


Foaming by fungi or

Thiothrix in bioreactor.


26/31


Foaming by fungi or

Thiothrix. The sludgedidnt be settled after24 hours


27/31


Foaming by fungi orThiothrix. The sludge

didnt be settled after

24 hours. Scum is darkcolor.


28/31


Foaming by high

viscosity matters


29/31


The sludge can notmake bio flocculationby cause of high F/M

ratio in bio reactor


30/31


The sludge wasbroken by cause of

high DO and low F/Mratio in bio reactor


31/31


The sludge wasfloated to thesurface of settling

basin by cause ofdenitrification.

bioprocess visual index

Documents