Hi mychicknpi.
Ha! What a topic! There is no direct answer for this, but considerations only. I am going for a long reply, so please bear with me.
The end comment that I have is the following and you won't like it: Electroplating as a hobby is not something I would suggest to anyone.
The main reasons are very simple:
1) Safety-related
2) Waste related - with legal connotations.
Let's break it down.
1) The safety aspect: Electroplating can be far more dangerous than soaping, if you touch lye, you might feel a burn, get a blister, a scar in the worst case and be done. If you spill a solution of nickel salt you might not notice it until you develop contact dermatitis, and chronic nickel accumulation has been shown to be carcinogenic. Inhaling powders of metal salts is not the best thing for you, and this includes nickel, copper, etc... Most electroplating solutions contain corrosive or caustic chemicals, and to that, we have to consider the added risk of electrical equipment. Of course, safety is a matter of personal protection, training, attention, and preparation in case accident happens. We assume that this will never happen and that everything is performed following Good Manufacturing Practices.
2) Waste related. This reconnects to your original post.
The answer here is only one.
NO, you cannot neutralize copper or nickel salts. The copper and the nickel will still be there, just as a different compound.
The reason is very simple. A former governor of NJ said it very well: In the US, Toxic is a matter of statute, not opinion.
EPA 40CFR 413/433 regulates the effluents (waste) of electroplating, electroless plating, etching, and anodization. This applies to businesses only, whether multimillion dollar corporations or one-man businesses.
When do you become a business? When you sell your products.
At this point you might say: "I am a hobbyist, so I do not need to comply!" Wrong.
In order to meet EPA regulations, the final concentration of Copper and Nickel in effluents is lower than 4.0 mg/L. If you have 1 oz of copper sulfate, you will need to dilute it in 730 gallons of water to meet EPA requirements.
Now, one could say: "what about the fact that you can buy electroplating kits online?" Well, the company that sells it has nothing to do with the waste. Their compliance ends the moment the shipment leaves their dock. Responsibility for the waste is ONLY attributed to the waste generator, you, FOREVER. Yes, let's say that waste gets stolen three times by three thieves in a row. You will still be responsible for it, no matter what. You pay a company to dispose of it? Should anything happens (mislabeling, unknown composition, accidents caused by the waste, etc...) you are still legally responsible for it unless you can prove it was mishandling by the company you paid.
The first heavily regulated chemical industry in the US was the Electroplating industry, and there is a good reason for that. Here is an example. A guy ran a garage chrome-plating operation between 1960-1970 and ended up with an EPA Superfund (Odessa Chromium#1). It took until 1983 of legal proceedings (we are talking about million dollars of legal fees), and the cleanup process is still ongoing as of 2017, 20 acres of groundwater contaminated, and you can imagine the amount of taxpayer money poured into this operation.
This was a small-medium, time-protracted event. So nothing on the scale you are talking about and with less toxic chemicals. However, the authorities do not distinguish one from the other. If you incorrectly dispose of something hazardous, you are liable no matter what is in there, and how much.
So, what to do in this case?
The first thing to do is contacting waste management companies. If there is a high-school or a college in your area most probably they have a waste management company they use for their hazardous materials. Local government agencies usually do not deal with this stuff and their operators do not know the details of your operations and how to deal with hazmat. So go with specialized companies. Call them and explain the situation. Ask for quotes and regulations.
Many companies will not accept hazmat waste of certain categories from hobbyists because you are not licensed by regulatory agencies.
It might be expensive. In my lab disposing of a metal-ion acidic solution costs us 300$/gal. Hence waste reduction practices need to be in place.
Another thing you can try is calling the closest EPA office you can find. Maybe you have one in your county, or neighboring ones, or in the closest big city. They will tell you most of the things I've told you, but they might be lenient and say they do not care since the amounts you will be handling are insignificant. Remember, you will be talking to an operator. If they do tell you that, you will still be legally and penally responsible, should anything happen to the groundwater, aquifer, wells, creeks nearby you. Is it likely to happen? NO.
Can it happen? YES. Especially if by accident you spill copper and kill all the fishes in your neighbor's Koi-pond and he rats you out.
If your daughter is interested in doing plating for college-related activities (promoted by the educational institution, it seems), then they MUST provide a mean for waste disposal. If not they are misleading/endangering those students, and possibly putting them in a position of non-compliance with environmental regulations.
IMO, the best way will be to search for small businesses that do plating around your area, look for family-run businesses, small shops, one-man businesses, plating services for jewelers. They have the expertise, the equipment, and the means to take care of the waste. In addition, the small businesses of that kind are slowly disappearing, because of the cheap mass-produced stuff that comes from overseas. No more young people get involved with this, so they might be welcoming a one- two-times-a-week apprentice in their shop. Asking never hurts.
And here is the conundrum of legislation, or, as mentioned before, STATUTE.
Copper and Nickel compounds are commonly used in crops and pest control. For example, copper is used in the Bordeaux Mixture and in the Burgundy Mixture, which are Copper Hydroxocarbonate suspensions, used in agriculture as spray-on fungicide for vines (grapes, tomatoes). Nickel is always present in fertilizers, at low concentrations, since it is an essential element for plant metabolism. The Mouse ear of pecans is caused by nickel deficiency and is easily solved with a nickel-based foliar spray or adequate fertilization of the soil.
The funny thing about that? Both treatments are classified as "organic".
I hope I gave you some food for your thoughts.
My mission was not to scare either you or your daughter but to warn you of the potential risks associated with this. Caution is advised before undertaking this kind of endeavor.
Best,
Lorenzo
