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When we speak of special waste, we usually mean “hazardous waste”. Under this term the EU waste catalogue lists almost 400 types of waste that are poisonous, explosive, combustible or corrosive, or which contain pathogens. Hazardous waste represents a risk to health and the environment. Specific examples include the special waste of the chemical processing industry, paste-like or liquid production residues, reactive or highly halogenated liquids, waste containing silicon and phosphorus, concentrates, laboratory chemicals, insecticides, pesticides, polychlorinated biphenyls, sewage sludge, hospital waste or severely polluted industrial waste.
When it comes to hazardous waste, proper waste disposal is essential. The substances must not be combusted with normal household waste and belong in plants that can facilitate high-temperature combustion. According to the Best Available Techniques Reference Document (BREF), treatment must follow the three “T”s: Time, Temperature and Turbulence. During the thermal treatment of special waste, temperatures of 1,100 degrees must be attained for at least two seconds in order to avoid emissions that are damaging to health and the environment. Only the high temperature guarantees the safe and certain destruction of all organic substances. Anorganic pollutants such as heavy metals are bound safely into the solid residues, allowing them to be subsequently deposited.
In principle we offer two methods for the treatment of hazardous waste: thermal treatment in a rotary kiln with temperatures around 1,200° C, or gasification in the Direct Melting System (DMS) at 1,800° C. Both methods solve the disposal problem cleanly and safely. Combustion in the rotary kiln and the DMS technique provide the possibility to recover electrical or thermal energy from the hazardous waste. This technology is currently the most suitable method for the safe and economically efficient treatment of large quantities of special waste.
Depending on the type, hazardous waste has different calorific values. One special feature is the higher calorific value in some cases, compared to household waste, and the fact that much of the waste is paste-like or liquid. Paste-like waste is difficult to treat with a grate system; combustion in this case causes increased slag flow, which covers the grate, and also to dripping and ignition beneath the grate. When combusting in a rotary kiln, attention should be given to a careful composition of the waste, due to the different calorific values. The storage and documentation of the waste is also more complicated. In addition, contamination-free zones must be created for clinical waste, and chemicals must be stored safely and separately. We are happy to advise you on the right storage concept, as well as on the application possibilities and the best solution for your requirements.