How to destroy (or use) large amount of polluted water?
Solution 1:
I would use it in the fertilizer synthesizer.
1) This produces natural gas, which can be used with the natural gas generator to make power. (The N.G. generator also produces more polluted water, but much less than the fertilizer generators consume).
2) You'll get a lot of fertilizer that you don't need, but storage seems to be unlimited if you just leave solid items on the ground.