Mitsubishi STERAPORE 5700 Series Instruction Manual page 47

3. Start filtration operation.
Start filtration operation after activating the anoxic tank mixer, the circulation pump, and the
blower to mix water and sludge well.
C AUT IO N
For each device, ensure that the water level is at or above the minimum water level at which
the device can be operated, and then activate the devices in order.
If seeding is diluted by raw water, perform aeration and start filtration after soluble BOD is
sufficiently processed.
Starting filtration operation when soluble BOD remains may cause a rise in trans membrane
pressure and membrane clogging. Estimate whether dissolved BOD has been processed or
not on the basis of raw water BOD concentration, sludge concentration, and tank capacity or
by COD pack testing.
4. Transition to Steady Operation.
When the MLSS concentration of the aerobic tank reaches about 5,000 to 6,000 mg/L, start
extracting sludge.
Adjust the amount of excess sludge extraction so that the MLSS concentration stays within the
specified range.
6-3-3 Problems at Start-Up and Responses
●
Foaming
Use an alcoholic, ether, or ester antifoaming agent if foaming occurs. Do not use silicon antifoaming
agents, as they cause membrane clogging.
●
pH decrease
A pH decrease may occur due to progress in nitrification or a lack of denitrification. Check the DO of the
aerobic tank and ORP of the anoxic tank and adjust the aeration volume and the sludge circulation
volume or perform intermittent operation of the blower. Note that pH is particularly subject to variation at
start-up.
●
Nitrogen removal rate not attained
The following are causes of high T-N concentration in treated water:
 Lack of progress in nitrification reaction
 Lack of progress in denitrification
Measure NO -N and NH
3
If NH -N remains in treated water, a lack of progress in the nitrification reaction is considered to be the
4
cause. Nitrification will not progress well at the early stage of operation due to a low concentration of
nitrification bacteria. However, if the aerobic tank's DO is maintained at 1 mg/L or greater, nitrification
bacteria will multiply as they acclimatize, to facilitate the nitrification reaction.
If there is little NH
considered to be the cause. Denitrification tends not to occur in the anoxic tank at start-up due to a low
MLSS concentration. Normally, this improves with a rise in MLSS concentration.
STERAPORE 5700 Series (FF) Instruction Manual
-N in treated water first to identify the cause.
4
-N and more NO -N than the theoretical value, a lack of progress in denitrification is
4 3
Chapter 6 Operation
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