Andrew Lee developed a zero-dimensional nanofiltration unit model for the watertap-org/watertap repository, focusing on steady-state simulation of single-phase liquid processes. Leveraging his expertise in chemical engineering, process simulation, and Python, he implemented configurable solute rejection, a single solvent recovery fraction, and options for electroneutrality constraints in the permeate. The model also allows users to specify pressure drop and temperature equality, supporting flexible design-space exploration. Built using Pyomo for robust unit modeling, Andrew’s work enables more realistic and efficient nanofiltration process simulations. He provided documentation and usage scaffolding to facilitate validation and adoption by engineers within the WaterTAP platform.