STERAPORE 5600 Series (FF) Instruction Manual
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6-3
MBR System Operation
6-3-1
Seeding Input
Seeding is put into the MBR system when it starts up.
Activated sludge from a plant which uses municipal wastewater as raw water and employs a screen with
relatively small openings for pretreatment is suitable as seeding. Highly concentrated sludge such as
return sludge is suitable when ease of transport and usability are considered.
An MLSS concentration of 3,000 mg/L or more is recommended to decrease MBR start up time, and
make membrane filtration easier. If a sufficient amount of seeding cannot be acquired, and the MLSS
concentration cannot be maintained (1,000 to 3,000 mg/L), supply raw water while taking the BOD-MLSS
load into account. (A BOD-MLSS load of 0.15 kg-BOD/kg-MLSS/day or below is recommended.)
If the MLSS concentration is lower than 3,000 mg/L, for instance, when the system starts up, set the
membrane flux lower than normal and gradually increase the MLSS concentration.
Membrane flux at start-up
(Reference value) = (Design membrane flux) × (Current MLSS concentration) / (Design MLSS concentration)
Sludge input is calculated using the following formula.
Seeding Amount Q = (Q1 + Q2) × n ÷ n´
Q1: Anoxic tank capacity
Q2: Aerobic tank capacity
n: Target MLSS concentration
n´: Seeding concentration (n´ > n)
BOD-MLSS load is calculated using the following formula.
BOD-MLSS Load =
[Raw water BOD concentration (mg/L) × Treatment volume (m
3
/day)] ÷ [Aerobic tank capacity(m
3
) ×
Aerobic tank MLSS concentration (mg/L)]
Record sludge properties such as seeding concentration (MLSS and MLVSS), pH, filter paper filtration
measurement, and viscosity as basic data.
C AU T I O N
If sludge from a sludge storage tank is used, use it only after confirming that the sludge is not
putrefied.
Do not allow any raw sludge extracted from a primary sedimentation tank to be mixed into
seeding.
Remove screening using an extra fine screen or similar before putting seeding into the system.
6-3-2
Starting Operation
Follow the procedure below to start operation.
1.
Discharge water used for water commissioning using a RAS pump, sludge withdrawal
pump or a temporary pump.
C AU T I O N
Do not use a permeate pump to discharge the water.
2.
Put seeding into the tank.