Where FFw,SKj is freshwater to sink ’j’ flowrate, FSRi,SKj is source ’i’ to sink ’j’ flowrate, FSKj is the sink ’j’ flowrate, CSRi is the concentration of contaminant in source ’i’, CFw is the concentration of contaminant in freshwater, and ZSKjis the concentration of contaminant in sink ’j’.
Figure 2a-b show examples of feasible source mixing. As long as the final cumulative load of the source Composite Curve (CC) touches or is below the endpoint (final cumulative load) of the sink CC, the maximum quality limit of the sink is still fulfilled (Eq 2). This is in-line with the concept of stream mixing. A dirtier source (higher gradient line) can be mixed with a cleaner source (lower gradient line) to fulfil the concentration or quality limit of the sink demand- Figure 2a. The cumulative load of sources is located below a load of sink CC means that the total allocated source streams have a lower concentration than the maximum limit of sink’s concentration- Figure 2b. Figure 2c is the example of infeasible source mixing as the cumulative load of the sources is above the sink’s requirement. In this scenario, more freshwater is needed by shifting the source CC to the right.