mix into kitty litter or concrete and make it a solid.. your regular waste disposer should then take it.
Best option!
fyi, concrete was banging up the blade on our ink mixer and didn't really want to cure/set in the 5gal buckets so we like kitty litter. About 50/50, to taste.
We got behind on desiccating our waste DC inks and had to dispose of 2 drums via the place that usually does haz stuff (it's not haz but as a liquid/gel can't go to the landfill) and it was like $250/drum I think. Kitty litter is a hell of a lot cheaper.
However you do it, kudos for doing it and not dumping it down the drain. We had a kid in here that only worked one day in our shop and mysteriously quit, but had come on good recommendation from another shop that does wb printing, and he said they just dumped all their inks down the drain there...maybe ok for a very small shop but imagine 100+ gallons of this going down the drain. While certain city waste systems can indeed handle this don't be that guy that does it, desiccating for proper disposal is easy.