Hi Chris. With regards to alkalinity dosing depends on what you are trying to achieve. If you are removing ammonia you need 7.2mg of Alkalinity per 1 mg of Nitrogen removed. SBR's will normally have an anoxic section which can recover alkalinity in the system if some dissolved BOD is left leaving a nett requirement of approx 4mg/l. However your influent may be having a big impact if it is acidic. Best way to control alkalinity is standard pH control loop dosing in the NaOH and then checking actual alkalinity on a daily basis. If Nitrifying suggest a target alkalinity around 500mg/l.  The settlement rate you have shown above is really poor and you are probably correct that your low pH level is causing the floc binders to split apart - however if it is a thick soup its likely to also be build up of significant trash and possibly non-organic solvents or even bacterial slime. It would be worth doing an MLSS test followed by vMLSS to see how much of your sludge is organic. If you can't empty and restart the SBR you are looking at a long slow road to recovery but it is feasible. You have made a great start with getting the pH working. If possible speed up the process by putting one basin into manual and continously aerating with the Nutrient make up I previously recommended. This basin can then act as the seed basin for your other SBR's.

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Hi Chris. With regards to alkalinity dosing depends on what you are trying to achieve. If you are removing ammonia you need 7.2mg of Alkalinity per 1 mg of Nitrogen removed. SBR's will normally have an anoxic section which can recover alkalinity in the system if some dissolved BOD is left leaving a nett requirement of approx 4mg/l. However your influent may be having a big impact if it is acidic. Best way to control alkalinity is standard pH control loop dosing in the NaOH and then checking actual alkalinity on a daily basis. If Nitrifying suggest a target alkalinity around 500mg/l. 

The settlement rate you have shown above is really poor and you are probably correct that your low pH level is causing the floc binders to split apart - however if it is a thick soup its likely to also be build up of significant trash and possibly non-organic solvents or even bacterial slime. It would be worth doing an MLSS test followed by vMLSS to see how much of your sludge is organic. If you can't empty and restart the SBR you are looking at a long slow road to recovery but it is feasible. You have made a great start with getting the pH working. If possible speed up the process by putting one basin into manual and continously aerating with the Nutrient make up I previously recommended. This basin can then act as the seed basin for your other SBR's.