Mixed waste is waste which contains two or more waste types. More specifically, in several areas of the world, the term “mixed waste” is used to refer to a very specific mixture of waste types, one which includes radioactive waste and another form of hazardous waste. For example, radioactive lead is mixed waste because it contains lead, a recognized hazard, and it is radioactive. Likewise, scintillation fluids are another example of this type of waste. Some very complex regulations cover the disposal of mixed waste of this kind, on the international and national level.
When used more generally to talk about waste, the term is often used in discussions which are intended to identify inefficient areas of the waste stream. For example, if food waste ends up in general household waste, it cannot be composted, increasing the load of material which ends up in the landfill. Likewise, some waste processing facilities accept mixed waste for processing, as seen as mixed waste recycling facilities which take recycling bins into which people dump plastics, glass, and so forth all together, with the facility doing the sorting.
In the sense of radioactive waste, mixed waste is governed by regulations which pertain to radioactive waste, and to other hazards present in the waste. Most commonly, mixed waste includes radioactive and chemical waste, although it may also include biological waste. This waste needs to be carefully handled to avoid creating environmental health threats, which can require neutralization of the nonradioactive portion of the waste along with other steps.
Mixed waste disposal is handled by specialized companies which are carefully scrutinized by regulatory agencies. Contracting with one of these companies is usually costly, with customers usually including research facilities, hospitals, nuclear power plants, and some other types of institutions. The waste disposal agency collects the waste, neutralizes other components, if possible, and processes it so that it can be safely stored or disposed of.
Companies which discard mixed waste without observing the proper protocol can get into legal trouble. They may be fined for improper waste disposal and ordered to pay cleanup costs, for example. For this reason, institutions and companies are careful about accepting materials which mix hazardous substances, and they monitor their use of such materials carefully to ensure that they enter the proper waste stream. Technicians who work with and dispose of such materials must also wear appropriate protective gear to avoid exposing themselves to hazardous materials.