Thank you guys for all the help.
About selling it. I'm not sure how that process goes. We are a very large government agency and I don't think we can't just sell it to someone without a ton of paperwork, which will probably cost more than getting rid of it. By the way, it's about $8k to get rid of it at our facility, plus it adds to our annual allowable wastes. My boss said that our facility is only allotted so much allowance to get rid of waste chemicals.(I don't know what the official term was for this.) We are trying to what we can to get that price down and also trying not to add to our facilities allowance.
About the purity. The reason we are getting rid of it, is because the manufacturer recommends it has useful life of about 3 years. And I think we have had it for about 5. We use it too clean components, that have paint, rust scale, whatever on it. I don't know why there is a life span if it's just NaOH. The pH is still registering a 13. But maybe it has to do with the additives in it. Anyway, it probably has a whole bunch of gunk in it that it has collected over the years and it probably not too pure anymore. Although, it still might be useful to someone who doesn't care about purity too much. Does anyone know any industry that might want this?
About the acid-base reaction. I'm not a chemist, but I did stay at a Holiday Inn and read a chemistry textbook last night. It looks like it will create a lot of heat and a dissolved salt solution. Maybe mixing with an acid is not a good idea. I wouldn't even know where to begin. How much should I mix at a time? What's the mixing process? What's the PPE? etc.
I see someone said CO2 will neutralize it. Can we get a tank of CO2 and create bubbles with it? How much CO2 will that take? How long will that take?
Also, I am learning how incredibly alkaline this solution is. I see the pH scale is logarithmic. I believe pH 13 is 1 million times basic than pH 7. Where as pH 11 is only 10,000 times as basic than 7. So, when looking at the big picture, trying to get a pH 13 solution down to pH 11, is almost like trying to get it to pH 7. It's very hard.
Also, we had a little explosion in the caustic tank in the past, and some of the NaOH solution got on the floor and a nearby table. No one was any where near at the time thankfully. The employees told me when the fire dept came, they sprayed vinegar all over. I got to researching vinegar and it looks like typical vinegar is a 5% solution of acetic acid, which is about pH 3. It looks like since NaOH is 13 and vinegar is 3, does it take 10 times more vinegar than NaOH to neutralize them? If so, then we need 10,000 gallons of vinegar to neutralize 1000 gallons of NaOH. ??
We also performed a little test yesterday to see how much water we need to neutralize it. We put a couple teaspoons of NaOH in a 5 gallon pail and filled the rest with water. We filled it completely and it was still saying pH 13. Wow thats amazing. It would take a whole bunch of water to dilute the amount of NaOH we have.