Effects of excessive or insufficient aeration in wastewater
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I would like to ask my friends: during the wastewater commissioning phase or in normal operation, if the oxygenation level is too high, exceeding 4 mg/l, and all other parameters such as the quality of the incoming water, pH, and SVI are within the normal design ranges, could such high oxygenation levels cause the sludge flocs to break apart? This would manifest itself as fine particles of sludge when measuring its sedimentation properties, resulting in poor sedimentation performance If the oxygen supply is insufficient, does the sludge turn black?
If the aeration volume is insufficient, the sludge will definitely turn black. The aeration volume is also related to the process: in the AO process, the DO level should be maintained at 2–4 mg/l, while in the SBR process it should be kept at 2–8 mg/l.
I think the activated sludge process involves maintaining a balance between the flow rate of water entering the system, its concentration, the nutrients present, and the amount of aeration; as long as this balance is maintained and there is no excessive oxidation, it’s fine. SBR is different: its organic load changes from high to low as the aeration time progresses. Excessive aeration during the later stages of the reaction is not beneficial for the microorganisms. Dissolved oxygen is the amount of oxygen remaining after the microorganisms have used it up; keeping the dissolved oxygen level high speeds up the reaction rate. As long as there are no dead zones in the biological tank and the dissolved oxygen level is sufficient, the sludge should not turn black