Half of the hazardous waste is processed by the industrial plants that produce it, the rest is transported to specialized collective centers. Do you know how it is treated then?

1. Incineration

The requirements applicable to incineration plants with respect to air emissions, aqueous discharges and solid residues are the same regardless of whether the waste treated is hazardous or non-hazardous.

On the other hand, special provisions are laid down concerning the methods of acceptance and reception of waste and combustion conditions. It is toxic when the installation incinerates hazardous waste. In Missouri, there are 16 collective centers for the incineration of hazardous waste, 13 centers specialized in evapo-incineration and more than 25 co-incineration facilities (mainly cement plants). In 2017, nearly 1.9 million tonnes of hazardous waste were handled by these three types of plants: 48% in dedicated centers, 40% in co-incineration plants and 12% in evapo facilities.

Not everyone in Kansas City is aware of all the waste management work required to make sure the residents can live in a clean and safe environment. If you live in the region you can rent a dumpter in Kansas City to remove all your unwanted waste materials including hazardous waste. But in the case of hazardous waste, extra precautions are needed and you will probably require an official authorization.

2. Storage

Some waste cannot be recovered under acceptable economic or technical conditions and because some areas are not equipped with an energy recovery center, this waste is then stored.

Waste is considered hazardous if it has one or more of the following properties: explosive, oxidizing, flammable, irritant, harmful, toxic, carcinogenic, corrosive, infectious, toxic for reproduction, mutagenic or ecotoxic.

Burial or storage will be reserved for the so-called ultimate waste from which the recoverable part has been extracted. Any waste that cannot be subject to organic recovery or as material is considered as ultimate.

The Ultimate Waste Storage Centers, formerly known as landfill sites, are classified into three categories, depending on the type of waste accepted.

Class 1 CSDU

Such a center is dedicated to hazardous waste, it receives industrial waste or the residues of the purification of incineration fumes from household waste and the sludge resulting from the decontamination of the flue-washing water. These toxic wastes are stabilized before storage to prevent any evolution of residues in the very long term.

The waste is stabilized with hydraulic binders or vitrification. A waste is considered stabilized when its permeability to water and its leachable fraction (lixiviation: any operation of subjecting a matrix -solid, pasty, pulverulent to the action of a solvent, generally water) were reduced and when its mechanical strength was improved. The waste is then buried.

CSDU 1 ensures waste containment by a geological barrier of at least 5 m with a permeability coefficient of less than 10-9 m / s and a geomembrane on the bottom and blanks of the facility. Leachate is drained and directed to a treatment plant. An impermeable screen (geomembrane + geological barrier) covers the site.

Class 2 CSDU

It accommodates non-hazardous waste: residual household waste, bulky non-recovered waste, refusal to sort selective collection or composting. It meets strict regulations for the recovery of biogas, rainwater drainage, leachate recovery, underground waterproofing and monitoring the quality of groundwater.

Class 3 CSDU

It is reserved for inert waste, such as rubble.

Solidification

Historically, this technique widely used in the nuclear field, was designed to react all the water free of waste with the binder, to give it a certain physical structure. Today, solidification brings together all the techniques that tend to give waste a certain physical structure.

Chemical fixation

A technique which consists in the immobilization of pollutants in a matrix, because of the formation of chemical bonds between the pollutants and the matrix compounds (for example: insolubilization of cations in the form of silicates, formation of aluminates, complexation of ion …).

Physical fixation, embedding or encapsulation

A technique which consists in enclosing in a sealed gangue the polluting components of the waste (micro-encapsulation in the case of an intimate mixture between waste and binder) or the totality of the waste (macro-encapsulation if the waste, already possibly treated is coated in its entirety).

Vitrification

Vitrification is a principle consisting of a physico-chemical retention of the pollutants of a waste in a vitreous matrix, obtained by a high temperature treatment. Such vitrification is obtained thanks to the clean components of the waste, as well as by possible additions.

Why different processes?

One of the peculiarities of one process with respect to the others is the nature of the reagents employed (inorganic and or organic) and possibly the additives which are very often added. The role of the additives is to complete the action of the binders in order to confer on the stabilized waste a certain number of physicochemical properties compatible with a desired objective of quality.

Processes using inorganic binders may be referred to as stabilization – solidification processes. It is then considered that chemical fixation and solidification will occur.

The processes using organic binders are coating processes. The so-called vitrification processes are most often stabilization – solidification processes. However, poor vitrification can lead to the only encapsulation of pollutants. Some vitrified waste can be valorized for example in road works.