For some reason, I was unable to watch the videos on FF or IE.
Soda ash - sodium carbonate - Na2CO3 - will do the same thing.
In my early years, I used sodium hydroxide (NaOH) a lot, for cleaning up solutions, but stopped when I realized it wasn't buying me anything. The metal hydroxides (MeOH) are very voluminous and took up about as much space as the solution I started with. They retain water (I seem to remember as much as 75%-90%) even though they feel dry. Filtering them is a real challenge.
Each metal, as a hydroxide, forms at a specific pH. Starting on the acid side, and adding NaOH, the MeOH's drop out in a definite order, starting at about pH 5.5-6.0. On paper, it would seem that you could get a clean separation of the various MeOH's, by adjusting the pH. In practice, this is very hard to do, as there is much cross contamination. I have tried this on several occasions, with some of my money making schemes.
The EPA tests solids for the presence of heavy metals by very slightly acidifying them to about a pH of 3 or 4 and then by analyzing the solution for the various heavy metals. Metals in metallic form will generally pass the test, since they don't dissolve. The MeOH's won't pass the test since they dissolve at that pH. In other words, MeOH's are toxic heavy metal wastes. Nothing has been gained by separating them from the solution, unless there's not much of them.
The iron or aluminum method of removing metals from solution is another story. The metal drops as metal, which usually isn't toxic waste, if you can rinse all of the chemicals out of it. The solution remaining is an iron or aluminum solution which is a very low level waste solution. I think this should be the way to go. Harold and Steve have made excellent posts covering this method which, I have a hard time finding. Maybe, they can outline a step by step.
This legal cleaning up of solutions might be the most important topic on this forum. We should all put our heads together.
The info on this forum is really getting spread out. One thread might have 5 topics on it. Nobody's fault - it just worked out that way. What would really be neat on this forum would be an index that is upgradeable. Dream on.