Ric,
I am an environmental engineer and have worked with industry for the past 26 years. Much of my work has been with the metal finishing/electroplating industry.
There are a number of ways to address the nickel issue. I am assuming that you have an nickel electroplating process. If you only have a nickel rinse stream and no other streams, you can chemically precipitate the nickel as a nickel hydroxide. This sludge material is desired by a number of recycling operations. Second, you can use ion exchange (IX). This is a very attractive and proven technology. You can pass the waste stream through an IX column, remove the nickel and reuse the water as a rinse source. When regenerated, the regenerant has a high conc. of nickel that can be recycled, or, with proper attention, it may be used back in the nickel plating bath. In a similar fashion, you can use membrance technology, i.e., reverse osmosis. This is a concentrating process similar to the IX process so that you still have a nickel based waste stream to handle. But, you don't have to worry about regeneration and chemical usage.
Note that I mention that I assume the waste stream is from an electroplating operation. You may be using an electroless nickel process. There as still similar recovery processes for this waste stream but require some additional processing.
Also, be aware that there are some compatibility issues that you should be aware of when using processes such as IX or RO.
I can provide you with some equipment suppliers who have experience in both IX and RO. Drop me an email and we can discuss.
Egor con_engr@chorus.net