Contaminants

Contaminants using Smart Burners

With thermal desorption all organic contaminants can be treated, as all these chemicals will vaporise at a given temperature and can be extracted from the surface for further treatment. Here is a ist of he most common pollutants found in soils and treated by thermal desorption (incl. Smart Burners )

Poly-aromatic hydrocarbons

Acenaphthene
Acenaphthylene
Anthracene
Benzanthracene
Benzo(a)Fluoranthene
Benzo(a)pyrene
Benzo(b)Fluoranthene
Benzo(k)Fluoranthene
Benzo[ghi]pérylène
Chrysene
Fluoranthene
Fluorene
Indeno(1,2,3-c,d)pyrene
Naphtalène
Phenanthrene
Pyrene

Petroleum hydrocarbon

Asphaltenes
Diesels
Gasoil
Heavy fuel
Kerosene
Paraffin
Benzene
Toluene
o-Xylene
m-Xylene
p-Xylene
Ethylbenzene

POP (persistent organic pollutant)

TNT (Trinitrotoluene)
DNT (dinitrotoluene)
Chlorobenzenes
DDD (Dichlorodiphenyldichloroethane)
DDE (Dichlorodiphenyldichloroethylene)
DDT (Dichlorodiphenyltrichloroethane)
Dieldrin
Dioxins
Endosulfan
Endrin
Furans
Hexachlorocyclohexane
Nitrochlorobenzene
Tétrahydropyrane
PCB (polychlorinated biphenyls)
Phenols

Chlorinated solvents & PIP (persistent inorganic pollutant)

Methylene chloride
Tetrachloroethylene
Trichloro-1 1 1-ethane
Trichloroethylene
Vinyl chloride


Cyanides
Mercury
Mercury(I) chloride

Hydrocarbons

The pure organic contaminants (only hydrogen and carbon) will not only be desorbed, but also be completely oxidized in the combustion chamber. There will be no other release into the atmosphere than CO2 and H2O.

Halogenated Hydrocarbons: PCB, Dioxins, Furans, Pesticides

The principle of desorption remains the same for halogenated hydrocarbons (chlorinated solvents, PCB, dioxins, furans, pesticides, etc.), i.e. that they will evaporate and be collected in the gas phase (their boiling points are all well below 550°C). Once oxidized, the halogens will remain in the gas phase and therefore a secondary gas treatment is required before release into the atmosphere.

Chlorinated solvents

The boiling point of chlorinated solvents is below 100°C, so the target temperature of the soil can even be below. This implies that these chemicals can also be treated in (ground)water.

Cyanides

Regarding the treatable inorganics, such as cyanides and mercury, their behaviour is very specific. Cyanides are desorbing easily (depending on the complexes, the boiling temperatures varies from 300°C to 420°C) and are oxidized to CO2 and NOx in the burner’s flame. In order to not exceed the limit values the exhaust gas composition needs to be followed carefully; otherwise a secondary treatment is required.

Mercury

Although obviously heavy metals cannot be treated thermally, mercury is a particular case. It can be desorbed as nearly all forms of mercury have boiling points well below 550°C. However, the off-gas cannot be oxidized. Therefore mercury impacted materials require special attention and a dedicated unit.

 

Off gas treatment

Combustion of off-gas

In all cases, hydrocarbons are volatilized during a thermal desorption process (the Smart Burners Technology process) and, as gases, they are conveyed to a combustion chamber where they are oxidized to CO2 and H2O, with a generation of energy.

Other treatment

In some cases hydrocarbons may contain other elements, like sulphur or chlorine, which are not oxidized to CO2 and H2O and need additional gas treatment in order not to exceed the emission standards set for the release of clean gasses into the atmosphere. Standard methods like condensation and the use of activated carbon are applied here.