What problems can occur if the retention time for the biological treatment of domestic wastewater is set too long?
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The aerobic retention time is approximately 5 days, while the anaerobic retention time is about 2.5 days. The designed water volume is high, but the actual amount of water used is very low; as a result, the retention time becomes too long. I’m not sure what problems this might cause
The sludge age tends to be long, making it prone to excessive oxidation and resulting in sludge aging. Thus affecting the operation of the wastewater treatment system and the stable achievement of discharge standards.
In such cases, a batch aeration method similar to SBR or CASS can be employed to prevent sludge aging.
If the ammonia nitrogen level is high, attention must also be paid to denitrification sludge mixing in the secondary sedimentation tank.
The biggest problem is that the activated sludge cannot be cultivated; the tank can only serve a sedimentation function and lacks biochemical capabilities, so BOD, ammonia nitrogen, and phosphorus cannot be effectively removed
Reduce aeration volume； An excessive residence time can easily lead to sludge aging.
Excessive aeration causes the microorganisms to float to the surface or undergo autolysis