Neutralisation

[MirJev]

Hi everybody!

I have a task to start a trial period for an industrial WWTP. It is rather simple, rotary drum sieve, equalisation tank with a neutralisation equipment (HCl and CO2 as acid, and NaOH as a base) and that's it. The desired level of pH is 6-9. And the plant is automatic
Concerning the fact that most of the time, the wastewater has good pH value, how should I test the equipment and show it to the investor?
My plan was to set the desired value of pH e.g. 9-10, and than the NaOH pump should start working. When the pH of water gets in the 9-10 interval, I would again set the 6-9 interval in order to start the HCl or CO2 pump.
Is this plan OK? Do you have some suggestions? Are there some potential issues I am not aware of?

Thank you in advance for your answers.

 

[MortenA]

It difficult to titrate with strong bases and acids. But apart from this it look OK. Remeber to make sure that your NaOH is mixed well with the water, at high concentration it get rather viscous

 

[MirJev]

Hi MortenA! I forgot to mention that we use 10% HCl and 1% NaOH, so there is no problem with viscosity.

 

[bimr]

You have not provided very many details so it is difficult to comment.

Acid and caustic chemical reaction times are in the order of 30-60 seconds, the carbon dioxide reaction will be much longer.

 

[MirJev]

@bimr
What additional information do you need?
Concerning the fact that I don't have experience with start-ups of neutralisation plants, I wanted to make sure that my plan is OK. Maybe I am not aware of some potential problems. I will have only two days to do the start-up and to give instructions to employees and hand them over the plant, so it is important for me to know every aspect of the start-up.

One additional information that could be of importance: complete plant was installed and chemicals were prepared back in August 2017. Since then it is waiting for the start-up. As far as I know, these chemicals don't have expiration date, right?

 

[bimr]

Information on the wastewater such as what industry the wastewater is generated, the flow variability, the wastewater strength, size of equalization tank, etc.