Desiccant is a substance that absorbs moisture and absorbs water. Consumers and manufacturers use desiccant in a variety of applications to extract moisture or reduce humidity. Usually the objective is to prevent other substances from decay or corrosion or to protect substances from mould and mildew. Most consumers are familiar with desiccants such as the silicon gels packages that come with a variety of products and labelled with warnings of "Throw Away" and "Do Not Eat." Disposing of used desiccant, regulated by the Code of Federal Regulations (21 CFR 172.892), does not require any special procedures because it is considered a food starch.
Put any used desiccant into a waterproof plastic bag such as a Ziploc bag and store it in any cupboard out of the reach of children. You can reuse the desiccant at another time and continue reuse it by reheating in a microwave. If the desiccant is lime-based, however, you cannot reheat or reuse. A lime-based desiccant actually changes into calcium hydroxide when it absorbs moisture. Refer to your packaging to determine what type of desiccant you have, whether lime, oxygen or silica gel.
Throw away the used desiccant if you prefer not to use it again. Simply dispose of the desiccant with your normal trash. According to the Code of Federal Regulations, desiccant is a non-combustible waste, unless it is lime-based. Dispose of lime desiccant in a place with no water present to prevent the possibility of fire. The calcium oxide in lime generates heat when in contact with water.
Dispose of large amounts of desiccant as you would any other industrial waste. This usually applies to businesses, but consumers too may have a large amount to dispose of. Consult your county authorities to determine the procedures required for disposal of dessicant in large amounts.
In the United States, you may dispose of desiccants in your normal trash. If you are overseas, however, you will need to check with that country's regulatory authorities for proper disposal.