The Netherlands | Like energy saving lamps, LCD displays –or ´flat screens´- contain mercury that can be released during collection and recycling. According to the European Electronics Recyclers Association (EERA), the number of displays that become waste is still low at present, but the association of prominent e-waste recycling companies wanted to know how much mercury could be released during collection.
To get a better insight research was conducted by Dutch research institute TNO in the recycling plant of one of the EERA members in the Netherlands. The outcome of this research will be used for making a standard on collection, transport, treatment and material recovery of LCD´s.
The EERA says, information on how much mercury is present and how large the chance is that ´backlighting` lamps of LCD displays break is difficult to obtain, which made the research a challenge. A number of ´worst case´ experiments were developed based on standard collection practices of WEEE. The collected displays were dropped into a 35 cubic meter container and the mercury vapours, temperature and humidity were measured for a period of 48 to 72 hours. After dedicated dismantling the number of broken backlights in the LCD displays was counted.
Approximately 30 % of the LCD displays contained one or more broken backlights It appeared that the concentration of mercury vapours in the air was highest 1 to 1,5 hours after the backlights were broken. Not until 16 hours the concentration of mercury vapours reduced from 10 ug/m3 to less than 1 ug/m3. The release of the vapours depends on the temperature and the amount of ventilation and can even last for days or weeks. During tests the air borne mercury concentration never exceeded the indicative limit for exposure of humans during longer periods of time.
Based on these findings EERA recommends to avoid uncontrolled bulk collection and storage of LCD displays in large containers and to prevent breakage of backlights by carefully handling the LCD´s.
The EERA also recommends to recycle LCD displays in dedicated treatment facilities, where mercury releases are controlled in such a way that potential health risks are avoided, no mercury is released into the environment and that potential contamination of materials coming out of the process does not hamper the subsequent recovery of these materials.
And the EERA advises recycling companies to consider the risk of mercury releases in every step in the take back or collection, transport, treatment and material recovery for policy making, permitting and developing standards.
Acknowledgement
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