Ah thank you for the reply! i can try to be a little more specific.
There is a 3 stage destillation process where you increase the concentration of NaOH up to 50% from 32%. The bisulfite is added before the first stage in a Falling film evaporator. Again this is all the info i have currently but my question really is more general. Why would you add Sodium bisulfite to NaOH ?
I read somewhere that it removes oxygen so as to decrease the corrosion in the system but again very vague. Some also says it reduces the amount of chlorine?
Any information really is helpful hehe