Environmental Engineering Reference
In-Depth Information
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symptom 7.
Return activated sludge has a rotten egg odor.
Cause:
Septic return
Corrective action:
Increase the aeration rate.
Cause:
Low return rate
Corrective action:
Increase the rate of return.
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symptom 8.
Activated sludge organisms die during a short time.
Cause:
Toxic material in the influent
Corrective action:
Isolate the activated sludge (if possible);
return all available solids; stop wasting; increase return rate;
implement pretreatment program.
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symptom 9.
Surface of the aeration tank is covered with thick,
greasy foam.
Cause:
Extremely old activated sludge
Corrective action:
Reduce activated sludge age; increase wast-
ing; use foam control sprays.
Cause:
Excessive grease and oil in system
Corrective action:
Improve grease removal; use foam control
sprays; implement pretreatment program.
Cause:
Froth-forming bacteria present
Corrective action:
Remove froth-forming bacteria.
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symptom 10.
Large clouds of billowing white foam are on the sur-
face of the aeration tank.
Cause:
Young activated sludge
Corrective action:
Increase sludge age; decrease wasting; use
foam control sprays.
Cause:
Low solids in aeration tank
Corrective action:
Increase sludge age; decrease wasting; use
foam control sprays.
Cause:
Surfactants (detergents)
Corrective action:
Eliminate surfactants; use foam control
sprays; add antifoam.
8.14 ProCess ConTrol CalCulaTions
As with other wastewater treatment unit processes, process con-
trol calculations are important tools used by the operator to optimize
and control process operations. In this section, we review the most fre-
quently used activated sludge calculations.
