WEEE: reducing chemical risks in existing and emerging sectors

Outline of reasons and objectives
The sectors and channels for treating Waste Electrical and Electronic Equipment (WEEE) have changed considerably in recent years due to the regulatory context and to the development of new technologies. In the existing and mature sectors, the means for action on occupational risk prevention are limited. Conversely, risk prevention actions conducted during the emergence phase of new sectors are more efficient for preserving worker health. The objectives of this study are to monitor the existing treatment sectors, to assist companies in industrialising their processes in the emerging sectors, and to optimise the treatment processes so as to reduce exposure to pollutants at source.

Approach
Assessments of chemical risks were conducted in the existing treatment sectors (cathode ray tube (CRT) screens, used light bulbs, and small household electrical appliances) and in the emerging sectors (flat screens) for each process and per unitary operation. The monitoring of the emerging sectors was conducted from the design phase of the processes onwards and continued up to industrialisation of them.
In view of the issues related to the presence of mercury in the treatment sectors, mercury material balances and a parametric study were conducted to determine the influential factors making it possible to optimise the processes for treating mercury waste.

Main results
All of the treatment sectors are affected by chemical risks. The sector most contaminated by pollution is the used light bulb treatment sector, in which the main pollutant is mercury. In the CRT screen treatment sector, the high levels of exposure remain a concern, with the exposure limit value for lead being exceeded. In the flat screen treatment sector, an initial phase of assessment of the pilot processes showed that the chemical risk would appear to lie mainly in the levels of exposure to lead. The pilot processes having the highest exposure levels were not selected during the call for bids, whereas the prototypes offering the lowest exposure levels were awarded the treatment contracts. A second phase of assessment on the new processes as industrialised showed relatively low exposure levels.
The mercury material balances in used light bulb treatment showed considerable variability in the distribution of the mercury in the various output fractions. The parametric study made it possible to determine the parameters that are influential in optimising treatment of mercury. All of this laboratory work on used light bulbs was used advantageously to assess the mercury treatment performance of an industrial process in the liquid crystal display (LCD) screen treatment sector.

Discussion
In this context of the development of new sectors, the proposed prevention approach satisfied the pragmatic requirements of recycling and of environment-friendliness. It enabled decision-takers and eco-organisations to be assisted in including a health and safety part in the specifications for the treatment companies. This had three benefits for occupational safety and health, namely:
making recommendations to process designers and to treatment companies;
seeking technical solutions for optimising processes in which emissions were too high;
selecting for industrialisation those processes that had the lowest exposure levels.
Ultimately, when the sector becomes mature, this initial approach will steer it “naturally” towards the “best available technologies”.