Using the membrane technology with Na membrane, usually the chloral water do not interact with the brine, the chloral water remains in the anodic area and the brine in the cathodic one. 

Only if something is mixing the compounds from the two areas after the electrolytic chamber to get sodium hipochlorate, In that case the solution is to add some chloral water until the pH is in the neutral area (NaOH will neutralize the hipochloric acid generated).

Hope this will help,

Paul

precipitation of the chlorate in an alkaline can be achieved using potassium or ammonium ( or even sodium if the alkalinity Is extreme). Basically the chlorate will want to come out if the concentrat ion is above the solubility, if it has the means, aka the potassium to form the salt. look at the temperature and pH of your water, find a chlorate salt that has the desired concentration at that temperature and pH, and dump in the other half of the salt aka potassium chlorate will precipitate if the concentration is above 8 mg /100ml at 25 degrees C (assuming at neutral pH as the solubility was found on wikipedia.)  increasing pH, more alkaline, likely will decrease solubility due to charge balance affecting water's dissociation, if you were adding potassium ions,  but adding a salt of potassium those effects would be different. 

My answer Would be to use ammonium, since you'd be adding ions and have easier precipitation, if you can be sure to safely handle, but this wikipedia page makes me think someone else has learned a hard lesson about ammonium chloride.it is extremely unstable and combustible( https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Ammonium_chlorate&ved=0ahUKEwiEhvWGrNXOAhVG8WMKHVLfDF4QFghBMAY&usg=AFQjCNGxEbxKw1UDIrgVawGP6G42ryJ9Wg&sig2=pt5gV3MGFAwvbiPnspJmLA)

so Potassium seems to be your best bet. more details on the conditions of water and process  would allow a more complete answer if you need it. but the idea is simple. find the right chlorate salt so your solubility equals desired concentration at your specific conditions.  excuse brevity and typos this was typed on my phone.