Hi Lin, The reactor temperature is much higher than my typical experience, but this should have a positive impact on nitrification. Because we don't know what the sludge age is, I would recommend that the MLSS is maintained at higher levels (and higher sludge age) rather than lower levels as a safety precaution for nitrification. From the info available I would say that the current problem was due to a reduction in alkalinity (due to nitrification or feed) coupled with an increase in ammonia concentration. Nitrification will utilise alkalinity resulting in pH instability and lower pH values. Lower pH values will result in lower nitrification rates (pH below 7.0 will significantly reduce nitrification rates as the pH reduces). I would therefore recommend that alkalinity/pH is adjusted upward by lime (or other base) dosing. pH adjustment should be accurately controlled as a high pH will also impact negatively on nitrification. If alkalinity/pH is not the problem, it could be some nitrification inhibitory substance in the feed or which became more prominent due to the change in load. Regards

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Hi Lin,

The reactor temperature is much higher than my typical experience, but this should have a positive impact on nitrification. Because we don't know what the sludge age is, I would recommend that the MLSS is maintained at higher levels (and higher sludge age) rather than lower levels as a safety precaution for nitrification. From the info available I would say that the current problem was due to a reduction in alkalinity (due to nitrification or feed) coupled with an increase in ammonia concentration. Nitrification will utilise alkalinity resulting in pH instability and lower pH values. Lower pH values will result in lower nitrification rates (pH below 7.0 will significantly reduce nitrification rates as the pH reduces). I would therefore recommend that alkalinity/pH is adjusted upward by lime (or other base) dosing. pH adjustment should be accurately controlled as a high pH will also impact negatively on nitrification.

If alkalinity/pH is not the problem, it could be some nitrification inhibitory substance in the feed or which became more prominent due to the change in load.

Regards