Disinfections are chemical substances designed to destroy or inactivate harmful bacteria on dry, non-porous surfaces. Disinfection doesn’t always kill all microorganisms, particularly bacterial spores; it’s less efficient than other chemical or mechanical processes, including sterilization, and usually kills only microorganisms of the same type, rather than all different types of microorganism. Disinfectants are often applied as a coating over the surfaces being treated, with the added benefit of protecting surfaces from airborne contamination, and they may be mixed into water and used as a spray, or to wipe down the surfaces after washing. A special type of disinfectant known as an autoclave can also be used, but it must be mixed with distilled water before use.

An autoclave is a mechanical device which heats up an atmosphere, such as air, to a specific temperature, where a natural chemical reaction takes place to remove contaminants. The process is not always successful: some contaminants can be broken down by the natural reaction, or by the application of other chemicals, such as disinfectant. Some contaminants, such as certain drugs, are too large to pass through the pores in the surface, and must be physically removed with chemical disinfectants. Some microbes, like yeast and bacteria, can also live without an oxygen environment for long periods of time, so are unable to be killed by the natural chemical reaction. In order to prevent the growth of these bacteria and fungi, and to kill them when they do grow, the chemical reaction must be repeated, so the surface is always clean and disinfected.

Although disinfection is a mechanical process, many forms can be automated. An autoclave is not the only mechanical device which can be used in disinfection – steam distillation is a common method. www.germetec.es uses boiling water or steam in a closed container to produce steam or water vapor which can then be passed over a porous material (such as wood or metal) at high pressure, vaporizing particles or substances. The amount of heat generated is very small and does not produce any kind of chemical reaction on the surface; the vapor can simply be evaporated, leaving no residue behind. Steam distillation can also be used to kill bacteria and fungus in liquids such as antifreeze and sewage, although this process is slower than that of the autoclave.