pH adjustment

[dangnm]

Greetings,

I am having a hard time finding a way to calculate how much H2SO4 to add to a landfill leachate. I would be using a 90 % solution of sulfuric and my leachate design flow is 375 gallons per minute with a pH of 11. My target is 9. I have calculated that I will need around 6 ml/min of sufluric.

Does anyone know of a program or easy method for estimating the volume needed?

Thanks, in advance, for your help.

Denton

 

[m777182]

The answer is not very straight: the amount of the acid needed to change the pH of your solution depends on the buffer capacity of the solution. In simple words buffer capacity is the amount of acid that changes pH of your solution for a unit pH. This quantity depends on pH itself, concentration of your solution, concentration of possible salts therein and sometimes on temperature. Basically it could be calculated for any solution but it would be much much safer to measure it simply by titration of your solution to your target pH. Do repeat measurements several times. If your solution is widely variable regarding the buffer capacity and the flow then it will be more difficult to trim the controller. In such a case you can do the job by a two stage addition of the acid.
m777182

 

[DentonM]

Thank you for your response. I suspected that there would be some buffering by the leachate. I don't have analysis of salts in the leachate, but I do know that the COD is around 30 mg/l and the TSS is about 10 mg/l. Do those results provide insight into the amount of salts or can I make some general assumptions about acid usage?

Is it possible for a lab to do the titration? If so, what type of analysis would I specify?

 

[saxon]

DentonM, Is the pH constant or does it vary? Does the concentration of base vary? If it varies, it will be next to impossible to establish an operational titration curve for the leachate.

As for the lab, if it's certified, it will be able to run a simple acid/base titration.

Hope this helps.
saxon