DC Voltage question for saftey

Good morning all, new member here. I have a question that I hope someone can help with. We have a client that has a propriety process that they are working on and they have done some trials with treating the process (liquid) with DC voltage between probes that are immersed in the liquid and this has helped with getting their liquid to a condition they want, which is killing bacteria. My question is they want to do a large scale treatment tank which will require 15Kw of 12VDC to do the treatment. What safety precautions do we need to do the protect the operators? Grounding, plastic tanks? Than you in advance
Lee

Well, the first safety concern that comes to mind is the creation of chlorine gas.

DC is not safe! I deal with DC power sources in the 300 - 400 volt range on a regular basis. I expect that if I ever become part of the circuit I will die.

The battery in my car is 12VDC.
Safety of 12VDC should not be a problem. Except if someone is wearing a ring and the ring gets between the -VDC and the +VDC.
Chlorine usually comes from salt. Is there salt in the water?
The voltage seems low and the current high. Your customer's calculations should be checked.