The rise in world population and industrialization in developing nations has tremendously
increased the demand for water and has resulted in wastewater contaminated with several
pollutants. Thus, wastewater treatment (WWT), reuse, and safe disposal have become
crucial for sustainable existence. We believe that generation of a maximal structure
(superstructure) comprising of all possible treatment methods and flow patterns using
a systems approach, followed by optimization to decide the best treatment pathway,
will enable efficient designing of WWT networks. In this work, the technologies/methods
involved in WWT such as sedimentation, filtration, membranes, adsorption, activated
sludge, etc. are modelled using material and energy balances, equipment design, costing
and environmental impact. Utilizing systematic methods (e.g. mixed-integer non-linear
programming, MINLP), we frame the WWT network selection as an optimization problem
for cost and energy minimization along with sustainable goals. In our analysis, we
demonstrate a case study of Municipal WWT and determine the best strategy in compliance
with the 1972 US EPA's Clean Water Act to reuse the treated water for cropland irrigation.
In the next step, we use the P-graph approach for solving the same problem and this
tool provides a ranked list of candidate solutions.