A solvent is a substance, particularly in liquid form, which is capable of dissolving or dispersing other substances called solutes. The solvents used in industrial applications are primarily organic compounds such as aliphatic or aromatic hydrocarbons, esters, ethers, ketones, alcohols, amines, and halogenated hydrocarbons. Unfortunately, the same properties that make solvents useful in industry also make them a potential threat to human health and the environment. The hazardous components of solvents tend to persist in the environment, and the land disposal of solvent wastes poses a major problem because of their ability to dissolve or penetrate polymeric liners and dewater clay liners.