Vitrification is a scientific process that involves converting a substance into a glass-like solid. The basics of this process are that a substance is cooled to a liquid form that will eventually harden to a solid state. This process is sometimes used as a pollution remediation technique. One of the benefits of using vitrification for this purpose is that the process provides in situ solutions. Another benefit is that vitrified storage holds waste in a more secure form.
When vitrification is used for underground pollution, four electric rods are generally inserted into the ground forming a square. Electricity surges through the electrodes and passes through the ground from one electric rod to another. As the electricity travels, the soil temperature is raised to extreme levels that cause the soil to melt. When the ground melts, the electric rods descend deeper, allowing the process to work at greater depths. Eventually, the supply of electricity is disconnected and the soil vitrifies, or cools into a glass-like state.
In the United States (US), the Environmental Protection Agency (EPA) notes that it employs vitrification as a pollution clean-up method. The EPA says that rainfall, groundwater, and wind are prevented from transporting chemicals offsite. Once the pollution is trapped within the solid, the permanent block is left in the ground. When blocks are located next to one another it is possible to use vitrification to connect them.
When such a process is conducted at the site of the problem, it is considered in situ. This means it is done in place, without transferring the problem to another location. In most cases, when vitrification is used as a pollution remediation technique, it has been in situ.
This process may also be used as a solution for radioactive waste. Such sensitive waste has commonly been stored in liquid form, often in underground tanks. Storing such materials as liquid poses numerous risks, such as leaking containers resulting in contaminated water supplies. The process of radioactive vitrification is different from other pollution remediation.
Vitrifying radioactive materials is generally more complicated than the process used for underground pollution remediation. For example, one company outlines its process as involving steps where the waste is converted to powder, then glass-making materials are added before the combination is melted and cooled. Another major difference is that vitrification does not provide completely secure storage for radioactive materials. This process is believed to limit the radioactive leakage. However, the vitrified blocks are still considered radioactive.