Mitsubishi STERAPORE 5700 Series Instruction Manual page 29

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Water temperature
If raw water temperature or aeration tank temperature rises to 40°C or above, biological processing
performance declines. In particular, nitrification using nitrification bacteria is susceptible to changes in
water temperature. The rate of reaction decreases in low temperatures and nitrification bacteria are
killed at high temperatures. For good biological processing, it is recommended that the temperature of
water in an aeration tank is in the range of 15 to 35°C.
Install raw water cooling equipment or aeration tank liquid cooling equipment if the water temperature
exceeds 40°C.
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Other pretreatment
If the raw water contains a substance that inhibits biological processing, it must be removed. Examples
include cyanide compounds and heavy metals such as hexavalent chromium. Examine in advance if
the water contains any such substances.
C AUT IO N
As a rule, do not directly put water that contains grease and oil into the activated sludge tank, as
the surfaces of microfiltration membranes become clogged if the membrane is smeared with
grease and oil such as animal and vegetable fats and oils, and mineral oils.
Do not put an excessive amount of coagulant into the dehydrator as uncoagulated coagulant in
dehydrator effluent may be absorbed into the membrane surface and cause membrane clogging.
Futhermore design the system so that dehydrator effluent does not directly flow into the
membrane tank.
RE F ER E NC E
 If a large amount of surfactant is mixed into raw water, it may cause foaming in the aeration tank
and cause problems such as sludge overflow.
STERAPORE 5700 Series (FF) Instruction Manual
Chapter 4 Pretreatment
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