Industrial water reuse, priced by its ceiling
Reverse osmosis to reuse-grade water, membrane distillation on the concentrate it cannot push, and a crystallizer at the end of the line.
The actual dark-mode canvas: reverse osmosis makes reuse-grade water, its concentrate is warmed by low-grade waste heat and pushed further by membrane distillation, and what is left crystallises to salt.
Why there is a second membrane at all
Reverse osmosis is pressure-driven, so it stops where osmotic pressure catches the pump — on this feed, 75% recovery at 25 bar is thermodynamically impossible and the solver says so with a number rather than failing to converge. Membrane distillation is driven by a vapour-pressure difference instead: only vapour crosses, there is no osmotic ceiling, and it concentrates the stream RO had to give up on. The catch is that it is a heat-driven process, so it is only cheap where low-grade heat is already being vented — at the concentrate's own 25 °C the flux is about 1 kg/m²/h and the module is pointless.
Unit ops shipped for this vertical
Solution-diffusion rating model, bounded by van't Hoff osmotic pressure.
Duty- or outlet-condition-specified energy-balance stage.
Vapour-pressure driven, so no osmotic ceiling — with the temperature polarisation a bulk-temperature model gets wrong.
MSMPR population balance — nucleation and growth set the mean crystal size.
Stream RO feed pressure, permeate conductivity and concentrate temperature from the plant's own historian into this flowsheet's twin comparison — a rising feed pressure at constant flux is fouling, and it is the number that schedules the next clean.
See the Digital Twin platform →Try it yourself
- ✓RO's osmotic ceiling reported as a number, not a shrug
- ✓Membrane distillation has no osmotic ceiling at all
- ✓94.9% water recovery, with the rest leaving as salt