The COD of the effluent from the aeration tank is unstable
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The COD level in the effluent from our anaerobic tank is 60–160 mg/L, while it’s around 18–30 mg/L in the effluent from the aeration tank; sometimes it even reaches 40 mg/L. Why is there such a large variation in the COD levels of the effluent from the aeration tank? We would like to keep this level around 25 mg/L, with minimal fluctuations. Are there any methods to achieve this?
If the COD of the incoming water varies greatly, then the COD of the anaerobic and aerobic effluents will also vary significantly. In the initial stage of a new tank, it is necessary to cultivate bacteria; therefore, the COD of the incoming water must be kept stable. A large tank can be used for this purpose. If the COD of the incoming water is too high, fresh water, river water, or aerobic effluent can be used to adjust it, while if it is too low, nitrogen and phosphorus should be added.