10 07 29 Master thesis Juliana Leon - e-Waste. This guide

Table 7: Average composition and weight of CPU, Laptop, CRT-monitor and LCD-monitor used
in this study.
Material Level 1 → CPU (1) Laptop (2) CRT-monitor (3) LCD-monitor (4)
↓ Material Level 2 kg/CPU (%) kg/laptop (%) kg/CRT (%) kg/LCD (%)
Ferrous metals 6.700 67.00% 0.554 18.47% 1.250 10.42% - -
Aluminium 0.380 3.80% 0.168 5.60% 0.200 1.67% 0.550 11.00%
Copper 0.120 1.20% 0.014 0.47% 0.500 4.17% 0.010 0.20%
Brass 0.020 0.20% - - - - - -
Metals (non defined) - - 0.560 18.67% - - - -
PWBs 1.320 13.20% 0.410 13.67% 1.200 10.00% 0.220 4.40%
Plastics 0.810 8.10% 0.420 14.00% 2.400 20.00% 1.900 38.00%
CRT - - - - 6.450 53.75% - -
Screen - - 0.600 20.00% - - 2.320 46.40%
Batteries, capacitors 0.080 0.80% 0.274 9.13% - - - -
Other waste 0.220 2.20% - - - - - -
Copper (from wires) 0.220 2.20% - - - - - -
Plastic (from wires) 0.130 1.30% - - - - - -
Total weight (kg) 10.000 3.000 12.000 5.000
(1) Adapted from Gmünder (2007), Ministerio de Comunicaciones et al. (2008) and Laffely (2007)
(2) Adapted from Ecoinvent data v2.01 found in Wolfensberger (2010)
(3) Adapted from Marthaler (2008), Laffely (2007) and Ministerio de Comunicaciones et al. (2008)
(4) Adapted from Ecoinvent data v2.01 found in Wolfensberger (2010)
2.3.5 Mathematical description
Let the number of flows in the system be n, the number of goods be q and the
number of materials be p. According to the mass balance principle, the mass of all
inputs entering a process equals the mass of all outputs of this process plus a
storage term that takes into account accumulation or depletion of materials in the
process. This principle is valid for total flows (Equation 5) as well as for individual
material flows (Equation 6).
∑
n I
F ˙
input
=
∑ F ˙
output
+ F ˙
storage
(5)
n O
€
∑
n I
m ˙ input
=
∑ m ˙ output
+ m ˙ storage
(6)
n O
As expressed in Equation 7, the aggregated flow for a material ( M ˙ ) is composed by
the sum of material € flows in each good ( m ˙ ).
q
€
M ˙
k
ij
= ∑ m ˙ ij (7)
k =1
€
€
16