To dispose of antifreeze and reduce the amount of damage it does to the environment, is to take your car to an auto service center that has an antifreeze recycling machine. Or a designated re-cycle facility.
If there are no antifreeze recycling machines in your area, then flushing it down the drain is the next best step, though it is illegal in some areas and can still cause pollution. You should call your local waste water treatment facility to determine if they can accept antifreeze. If they can, then you can flush anti freeze diluted with water down your drain one gallon at a time. The best time to flush the diluted antifreeze is usually during the week, when the sewage system is in full use so that the antifreeze can be passed through the system quickly. If you have septic systems do not flush down the drain.
Additionally, some landfills or garbage transfer stations accept non hazardous antifreeze, in most cases this information can be found online on the company or government websites.
If you have spilled antifreeze do you best to collect as much as possible using towels and or mop and water and dispose the collected antifreeze diluted with water as stated above.
Antifreeze should not be poured down storm drains, into rivers or on the ground.
Store Antifreeze in a closed container away from animals, as they can be attracted to its scent.
Do not mix antifreeze with any other waste product that is thrown in the trash.
Use only properly labelled containers to reduce the possibility of mixing chemicals.