In 2001, Thermopower Process Technology established a permanent facility in Olifantsfontein, Midrand, for the treatment of hazardous waste by a process known as thermal desorption.
“A lengthy environmental-impact assessment was undertaken and, since October 2001, the facility has been running under a commissioning authorisation, during which period frequent inspections were carried out and detailed reports on all activities were submitted to authorities,” consulting engineer Dr Christos Eleftheriades informs.
The record of decision was received in June, allowing the facility to treat between 20 t and2 000 t of contaminated material a month, depending on its hazardous-waste content.
Eleftheriades stresses that the thermal desorption technology is reconised by the Basel Convention as a noncombustible process that is acceptable for the destruction of hazardous materials.
“The only legal alternative waste-management system in South Africa is exportation or encap-sulation of chemical and hazardous waste, which just delays the problem for future generations to deal with,” MD Derek Oldnall adds.
He states that, while numerous companies around the country have used these disposal methods in the past, a growing number of companies are turning to thermal desorption to deal with their waste.
These companies produce wastes that areclassified as persistent organic pollutants (POPs), such as polychlorinated biphenyl (PCB) transformer and capacitor oil, halogenated pesticides and herbicides, organic solvents and hydrocarbons.
The waste-treatment technology revolves around a three-stage process, the first two steps of which require thermal equipment.
In the first pyrolysis step, continuous- or batch-thermal desorption is achiev-ed by feeding solid and liquid wastes into a rotary thermalretort, to break the toxic compounds down into small carbonaceous molecules by heating them to temperatures between 150