Hazardous processes
E-waste management practices comprise of various means of final disposal of end-of-life equipment. In the hierarchy of end-of-life disposal methods, landfilling is considered the most harmful, and recycling the most environmentally tolerable.
Incineration
Open burning
Landfilling
Wet Acid Leaching
Recycling of components containing hazardous compounds
Due to the halogenated substances found in plastics, both dioxins and furans are generated as a consequence of recycling metals from e-waste. Halogenated substances contained in e-waste, particularly brominated flame-retardants, are of concern during the extrusion of plastics, which is part of plastic recycling. Due to the lack of proper identification of plastic containing flame retardants, most recyclers reject all plastic from e-waste.
Environmental problems during the recycling of e-waste are not only linked to halogenated substances. Hazardous emissions to the air also result from recycling of e-waste containing heavy metals such as lead and cadmium. These emissions could be significantly reduced by means of pre-treatment operations. Another problem with heavy metals and halogenated substances in untreated e-waste occurs during the shredding process. Since most e-waste is shredded without proper disassembly, hazardous substances, such as PCB contained in capacitors, may be dispersed into the recovered metals and the shredder waste.
The air emission fraction (ratio of kg emitted dangerous substance per 1000 t input of appliance) calculated for the selected appliances showed that lead emissions from recycling of PCs and TVs are the highest in comparison with the other appliances. Main contributors to these emissions are the copper and lead recycling operations1.
Inappropriate reprocessing and recycling procedures damage the environment as well. This becomes a relevant fact as some e-waste dismantlers send their light weight fraction to cement kilns for use as an alternative to fuel.
Due to the halogenated substances found in plastics, both dioxins and furans are generated as a consequence of recycling metals from e-waste. Halogenated substances contained in e-waste, particularly brominated flame-retardants, are of concern during the extrusion of plastics, which is part of plastic recycling. Due to the lack of proper identification of plastic containing flame retardants, most recyclers reject all plastic from e-waste.
Environmental problems during the recycling of e-waste are not only linked to halogenated substances. Hazardous emissions to the air also result from recycling of e-waste containing heavy metals such as lead and cadmium. These emissions could be significantly reduced by means of pre-treatment operations. Another problem with heavy metals and halogenated substances in untreated e-waste occurs during the shredding process. Since most e-waste is shredded without proper disassembly, hazardous substances, such as PCB contained in capacitors, may be dispersed into the recovered metals and the shredder waste.
The air emission fraction (ratio of kg emitted dangerous substance per 1000 t input of appliance) calculated for the selected appliances showed that lead emissions from recycling of PCs and TVs are the highest in comparison with the other appliances. Main contributors to these emissions are the copper and lead recycling operations1.
Inappropriate reprocessing and recycling procedures damage the environment as well. This becomes a relevant fact as some e-waste dismantlers send their light weight fraction to cement kilns for use as an alternative to fuel.
Incineration Incineration is the process of destroying waste through burning. Because of the variety of substances found in e-waste, incineration is associated with a major risk of generating and dispersing contaminants and toxic substances. The gases released during the burning and the residue ash is often toxic. This is especially true for incineration or co-incineration of e-waste with neither prior treatment nor sophisticated flue gas purification. Studies of municipal solid waste incineration plants have shown that copper, which is present in printed circuit boards and cables, acts a catalyst for dioxin formation when flame-retardants are incinerated. These brominated flame retardants when exposed to low temperature (600-800°C) can lead to the generation of extremely toxic polybrominated dioxins (PBDDs) and furans (PBDFs). PVC, which can be found in e-waste in significant amounts, is highly corrosive when burnt and also induces the formation of dioxins.Incineration also leads to the loss valuable of trace elements which could have been recovered had they been sorted and processed separately. |
Since open fires burn at relatively low temperatures, they release many more pollutants than in a controlled incineration process at an MSWI-plant. Inhalation of open fire emissions can trigger asthma attacks, respiratory infections, and cause other problems such as coughing, wheezing, chest pain, and eye irritation. Chronic exposure to open fire emissions may lead to diseases such as emphysema and cancer. For example, burning PVC releases hydrogen chloride, which on inhalation mixes with water in the lungs to form hydrochloric acid. This can lead to corrosion of the lung tissues, and several respiratory complications. Often open fires burn with a lack of oxygen, forming carbon monoxide, which poisons the blood when inhaled. The residual particulate matter in the form of ash is prone to fly around in the vicinity and can also be dangerous when inhaled. Landfilling Landfilling is one of the most widely used methods of waste disposal. However, it is common knowledge that all landfills leak. The leachate often contains heavy metals and other toxic substances which can contaminate ground and water resources. Even state-of-the-art landfills which are sealed to prevent toxins from entering the ground are not completely tight in the long-term. Older landfill sites and uncontrolled dumps pose a much greater danger of releasing hazardous emissions.Mercury, Cadmium and Lead are among the most toxic leachates. Mercury, for example, will leach when certain electronic devices such as circuit breakers are destroyed. Lead has been found to leach from broken lead-containing glass, such as the cone glass of cathode ray tubes from TVs and monitors. When brominated flame retarded plastics or plastics containing cadmium are landfilled, both PBDE and cadmium may leach into soil and groundwater. Similarly, landfilled condersers emit hazardous PCB's. Besides leaching, vaporisation is also of concern in landfills. For example, volatile compounds such as mercury or a frequent modification of it, dimethylene mercury can be released. In addition, landfills are also prone to uncontrolled fires which can release toxic fumes. Significant impacts from landfilling could be avoided by conditioning hazardous materials from e-waste separately and by landfilling only those fractions for which there are no further recycling possibilities and ensure that they are in state-of-the-art landfills that respect environmentally sound technical standards. |
1Source: Crowe, M et all, 2003, Waste from Electrical and Electronic Equipment (WEEE)- quantities, dangerous substances and treatment methods, European Topic Center on Waste, European Environment Agency.
