Wallpaper adhesive is also commonly known as wallpaper paste. It can come pre-mixed or it can come as a powder that you mix yourself to manufacturer's directions.
Modern wallpaper adhesive is considered a non-toxic and non-hazardous substance, and can be treated as such during disposal. If you have any questions about the type or kind of wallpaper adhesive you are using, contact your local recycling or landfill centre about disposal.
Mix up any remaining wallpaper adhesive with water and turn it into a slurry.
Pour it down your toilet and flush.
Allow remaining and leftover wallpaper adhesive to completely dry out.
Peel or break off the leftover dried adhesive and dispose of it in your regular trash.
Wallpaper adhesive is considered a non-hazardous industrial waste and therefore can be readily disposed of in mainline sewer systems or allowed to dry and placed in landfills with no harm to either of them.
Do not dispose of wallpaper adhesive in septic systems. Although small, there is a chance that particles can dry and gum up a closed septic system.