2 replies to this topic

[Valentino111]

Hi All,

 

I am seeking your assistance, I am interested in controlling the pH of industrial water by manually dosing calculated amounts of Acid/Base the effluent contains variety of organic as well as inorganic pollutants. I have taken into consideration an automated system but that is just not economically feasible for the process.  

 

I have been using the formula C1V1 = C2V2 in order to determine the amount of volume to add into the water to be able to increase the pH from low to a higher pH  and in order to determine the H+ ions in the water i have been using pH = - log[H+] and has been working slightly well in the lab as it does give me the amounts which i should add to increase the pH and when it comes to decreasing the pH not really well. And when it comes to applying this formula in the industrial process it does not work at all as it gives me very high volumes higher than the actual size of the treatment process. 

 

Are the any suggestions what other formulas I can use to actually do this task successfully at an industrial scale. 

[Francisco Angel]

Hi Valentino:

Sure in the industrial process you have many species interacting. What you are trying to do is a forward control strategy, the characteristic of this type of control is that you must know precisely the relation between the controlled and manipulated variable, and of course if your current theory about them is not accurate enough, you will not reach your set point.

Sampling is a subject on is own, both sampling for determining the acid/base quantity to add and sampling for determining the effectiveness of the treatment.

I would suggest that you take a backward control approach, take a sample, add base/acid as necessary (maybe a quantity smaller than theoretical to avoid overshot), check the pH and correct deviations from set point.

You will need to develop a procedure for this, how to take samples, specify times to do it, etc that suits your process.

Hope this helps.

[Napo]

Dear Valentino 111,

 

I send information that can you help, from "Calculation&Shotcut Deskbook", published by Chemical Engineering, p. 50-51.

 

Napo.

Attached Files

•  Adjusting pH.pdf   1.38MB   12 downloads