Disposing offset printing ink into the garbage is illegal in most countries. Check with local authorities or with your local recycling company to find our more information. Illegally dumping offset printing ink can result in expensive fines.
A licensed chemical waste disposal company should be used to dispose of the ink. They will require any safety data sheets you can provide.
Larger ink companies will also provide this service. They will take the used ink back and refine it to use again. Some will even give this service for free.
If this service isn’t available to you then this will likely get expensive. There are many companies that specialize in offset printing ink disposal and it can be expensive because they use incineration methods to dispose of it. Here is one.
You must keep a record of waste disposal including all paperwork provided by your recycle company. Government authorities come knocking from time to time to check on this.