Dry ice should not go in the trash. Dry ice can be disposed of in a well-ventilated area at room temperature. Let the ice sit and sublime. Do not leave dry ice unattended and do not store it in a cold room, storage closet, or warm room unless there is proper ventilation as this substance sublimes. If placed on or in any plumbing appliance such as a sink or tub, the dry ice could break the appliance due to the large temperature difference.
Warning: if placed in a container that is not ventilated, dry ice has a risk of exploding. Dry ice in an unventilated area may also pose risk of suffocation. The presence of carbon dioxide gas when the dry ice sublimes can cause an oxygen-poor atmosphere. Additionally, dry ice can cause frostbite once making contact with skin. Handle with care.