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is too high, please replace the sludge or transfer the sludge to the sludge storage tank until
an appropriate viscosity value is attained.
(6) DO
It is desirable that DO value is 1.0 mg/L or more at any point in the membrane submerged
tank. If DO is less than 1.0 mg/L, the additional aeration system may be necessary or the raw
water flow should be reduced.
(7) pH
The desirable pH range is 6 to 8. If pH is out of this range and the activated sludge property
is not good, please adjust pH by adding acid or alkali.
(8) Liquid
temperature
The desirable liquid temperature is 15 degree C to 40 degree C. If the temperature is out of
this range and the activated sludge property is not good, it is recommendable to take
corrective measures to cool or heat the liquid.
(9) Liquid
level
Check the liquid level of the membrane submerged tank is kept in the appropriate range. If
this requirement is not met, check (i) the liquid-level meter, (ii) the suction pump, and (iii) the
trans-membrane pressure, and when necessary, take corrective actions, such as adjusting
the control system.
