SUbstance flow analysis of the recycling of small waste electrical ...

66 Substance flow analysis of the recycling of small WEEE
EITO published data on sales of desktop computers between 2003 and 2007 that were
reproduced by IVF (2007). Like for mobile phones, the sales data for the previous years were
assumed to be proportional to the sales of personal computers in the USA.
Data on penetration rates of mobile phones and personal computers in the USA and in
Germany are supplied by BITKOM (2007). In 2006, the penetration rates for personal
computers amounted to 45% in Germany and 89% in the USA (related to the number of
inhabitants, not to the number of households), whereas the penetration rates for mobile
phones amount to 104% in Germany and to 76% in the USA. These numbers were multiplied
by the population in both countries and divided by the total lifetime to estimate the theoretical
waste generation (Table 13).
Table 13
Generation of end-of-life mobile phones, desktop personal computers and CRT monitors
in the USA and in Germany estimated with three different methods (in tonnes)
Country Equipment group Total
lifetime
Simple delay
Distribution
delay
Batch
leaching
Germany Mobile telephone 6 years 2 169 2 273 2 817
Desktop personal computer 9 years 43 827 39 957 50 097
USA Mobile telephone 6 years 16 197 14 916 7 532
Desktop personal computer 9 years 335 051 305 995 362 511
Table 13 shows that the ‘batch leaching’ method mostly leads to a higher estimate of the
waste generation than the other two methods (except for mobile phones in the USA, maybe
because of insufficient accuracy of the data used for the calculation). This is due to the
market dynamics (Wen et al. 2009). If the stocks of EEE in households and businesses are
increasing, i.e. if less WEEE is discarded than new EEE is bought, the current stock is not a
reliable indicator of the waste generation. Other researchers mention that the ‘batch leaching’
method is not appropriate for dynamic markets (Table 6). The methods ‘simple delay’ and
‘distribution delay’ delivered comparable results (difference smaller than 10%).
Insufficient sales data were available to apply the methods ‘simple delay’ and ‘distribution
delay’ for the other equipment groups. The method ‘batch leaching’, in spite of its
disadvantages (above all overestimation of the generation when the stock is increasing and
underestimation when the stock is decreasing) and the high uncertainties, was used to
estimate the generation for the other equipment groups. In total, the calculations using the
‘batch leaching’ method show that around 330 000 tonnes of sWEEE were generated in
Germany in 2007, and around 2 700 000 tonnes in the USA. The detailed results and the
assumptions are presented in Appendix 5.