Dear Lin. Is the wastewater domestic or industrial? 1. Do you know the cause of the pH drop? Is this the untreated wastewater or after treatment? You will not nitrify at pH 5.6 2. Is this wastewater temperature? You are on the edge of nitrification at 35oC. You will need sludge age of at least 12 days, preferably 18 days for full nitrification at this temperature. 3. If you have a sludge from another plant, this is good. But, the conditions need to okay. I suggest you raise the pH to at least 6.5. What is the alkalinity? You will need at least 300mg/l as CaCO3 for 40 mg/l NH3 and a minimum of 50mg/l after full nitrification to prevent pH drop, Do you denitrify and recover the alkalinity? 4. Is this pH increase after treatment or have you increased by manual alkaline addition? 5. ISO9509 is available on the internet

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Dear Lin. Is the wastewater domestic or industrial?

1. Do you know the cause of the pH drop? Is this the untreated wastewater or after treatment? You will not nitrify at pH 5.6

2. Is this wastewater temperature? You are on the edge of nitrification at 35oC. You will need sludge age of at least 12 days, preferably 18 days for full nitrification at this temperature.

3. If you have a sludge from another plant, this is good. But, the conditions need to okay. I suggest you raise the pH to at least 6.5. What is the alkalinity? You will need at least 300mg/l as CaCO3 for 40 mg/l NH3 and a minimum of 50mg/l after full nitrification to prevent pH drop, Do you denitrify and recover the alkalinity?

4. Is this pH increase after treatment or have you increased by manual alkaline addition?

5. ISO9509 is available on the internet