Forward OsmosisHistory, ancient and recent, &Some successful viable applications

John O. Kessler, physics dept, University of Arizona, Tucson kessler@physics.arizona.edu

"Carchorodon megalodon, Helicoprion and Edestus" prehistoric practitioners of FO

And heres a more recent expert in FO: Using seawater diffusing through semipermeable gill/mouth membranesas the source of fresh water

The basis of FO to the sharks blood: urea and triethylamine oxide (TMAO)Like other sharks, the Great White's bodily fluids also contain small organic molecules. Among the most important of these from an osmotic standpoint are urea and trimethylamine oxide (or TMAO, for short). Both urea and TMAO are nitrogen-containing break-down products of protein metabolism. Urea is highly toxic to living tissue at moderate to high concentrations, causing proteins to de-stabilize and thus cease to function properly or at all. That is why, although we can tolerate 'holding it' for a little while, we must eventually excrete urea or face dire physiological consequences. Yet sharks routinely retain bodily concentrations of urea that would kill most other vertebrates. This is largely due to the presence of even higher bodily concentrations of TMAO, which counters the protein-de-stabilizing effects of urea. Together, urea and TMAO add substantially to a shark's osmotic pressure, effectively rendering the internal fluids slightly (about 5%) 'saltier' than the external environment. As a result, sharks do not need to invest any metabolic effort toward obtaining the water their bodies need. A constant supply of fresh water osmoses passively into a shark's body through the gills and other exposed membranes.

Dunaliella salina, a halophyte alga that uses synthesis of glycerol to match osmolarity of exterior salt concentration,even when it increases, e.g. due to evaporation. BUT, when the exterior salt concentration drops, Dunaliella can metabolize and/or discharge glycerol.

Dunaliella in sea water

Dunaliella produce glycerol and carotenes, the cause of reddish color in conc. brine ponds.Note crystal of salt: they can cope!

?from sharks & algae to irrigation?Sharks UreaFertilizerArizona agriculture needs:Conversion of brackish water to water usable for irrigationHave brackishHave membrane? FDFOFertilizer-driven forward osmosishmmmChuck MoodyBob Riley

Chuck MoodyBob RileyTracing flow of ideas 1970Together withand action_____________________________________________________Unbacked cellulose acetate membranes

Well, it worked!Then Chuck Moody went to Peace Corps. When he returned we renewed this R&D, with matching grant ($15K) from OWRT (office of water research and technology), and help from Univ Az VP Research, Dick Kassander Well, it worked!

From FDFO to Sugar PiUsing fertilizer solution as a driver: large scale application

What about powdered nutrient FO Driving Solution?

Interesting: Calorie and water requirements well matched! hmmmm~lifeboats, infiltrators, lost souls SO inquiry at US Navy..BUMMER! nyet.. no $$. ( they said exposure bigger problem than thirst!!)

Oh well, on to science, efficiency, new applications __________________________________________________________

The next phase: problems, new approachesRecyclable driving (=draw) solutesConcentration polarization (boundary layers)How to eliminate? Stirring? Flow cycles? Membrane degradation, membrane design! etc, etc and etc! (and getting others, here, elsewhere to read about, notice our work!) Throughout Chuck Moody and Bob Riley have putin years of skill, hard work, insight and progress.