Neutralization Tank programming

This project should be pretty simple. Just need decide if I’m going to make it a batch or countious system (or both and let the customer select the more)

It’s a pretty small system (200 gallon tank).

The waste stream volume rate is unknown yet, but it’s going to be a rinse water that is slightly acidic. I’ll dose NaOH to adjust the pH.

What’s the most common mode for a system this size?

Batch - wait til the volume reaches X % then adjust he pH and close all stream coming to the tank. Drain, then open feed valves.

Continuous - as long as volume is in between low and high, and pH is under setpoint for x amount of time. Adjust and drain until more waste comes, close drain and do it all over again.

I think if you can build the system to be batch or continuous and be operable selectable it would be more flexible, especially if it is in a validated environment. In my experience it is easy to make several changes when qualify and a lot harder to make few afterwards.

A big factor in the equation would be the concentration of pH of the sodium hydroxide used for neutralize vs. how acidic the influent of the system and how heavy it is buffered. That would give you an idea of whether it can be done "on the fly."

In my experience heavily acidic process water needs a certain amount of contact time to be effective. Then you would also have to worry about overdosage.

Where I work we used to neutralize ABF (ammonium Bi-fluoride) rinse water from a washer that varied in runtime. We had 4 5000 gallon tanks that rotated and neutralized based on batch, hold for x amount of time of acceptable pH and then pumped to sanitary sewer system.

I hope this helps some.

It would depend on the facility and how flexible they could be. Meaning, if one batch has to "percolate" longer or has a longer retention time or even much longer than average, is there enough upstream buffer to accommodate?

Local permits would probably indicate what that buffer is if any. I know they spell it out for us. One thing that I have wanted to do is to move toward a batch system.
I would have a tank and a recirc pump and 2 pH probes installed in a wet-tap on either side of a 3-way valve. I would fill the tank and then start the recirc. The recirc pump would pull the influent from the bottom and up through the 3way valve and then back into the same tank. All the time a pH probe is reading actual pH of the influent being circulated.
Once my control has neutralized the influent, I would then actuate the 3way valve and then pump the tank out to post treatment/clarifier. The second pH probe would be a "final check" in case the other probe had failed.

Definitely get a titration chart completed with the solution you will be neutralizing and the "neutralizer" whatever it may be. This will show you how your control model should perform.

A hybrid continu-batch would be the most flexible but I would prepare for two different control models for each one. Retention time is generally a lot longer in continuous systems, usually using multiple different "tanks". Each one just tweaks the pH in.

I also wanted to mention that there may be specifics in the local permit for primary, secondary containment. i don't know, I have not directly been involved entirely with our permits. Just a heads up in case of gotchas.