Figure 8: Source and sink CC for SK1+SK3 in contaminant cascade ’A’ (a)
Before shifting source CC for SK3 (b) After shifting source CC for SK3
The step is repeated again for the sinks that are in contaminant cascade
’B’. The source ranking order based on contaminant ’B’ is
SR4->SR3->SR2->SR1. The design
first starts with SK2. If the sources are allocated based solely on
prioritisation of SR4, the Pinch occurs at contaminant ’A’ (see Figure
9a). This is not optimal as SR3 can still be allocated due to the limit
for contaminant ’B’ is not reached. The flowrate of SR4 is then reduced,
and SR3 is used until both contaminants have Pinches (see Figure 9b).
The identical scenario is observed for SK4 (Figures 11c and d). Notice
that in Figure 9d, a triangle is formed around the source and sink CC
for contaminant ’A’. This is feasible as the final load of contaminant
’A’ for SK4 is still satisfied.
The Composite Curves show exactly the sources to be allocated for each
sink. This is because the freshwater target and the Pinch are determined
sequentially for each sink. By doing this, the simultaneous target and
source allocation for each sink can be obtained. The allocation of
sources is directly connected to the network design as well. The
detailed illustration of the source allocation to the sinks is shown in
Figure 10.