HTI - Forward Osmosis Overview MSSC 2012
Introduction to Forward Osmosis at HTI Founded in 1987 as Osmotek, Inc., HTI is located in Albany, OR A new R & D facility was opened in August, 2010 and is located in Corvallis, OR Developer and manufacturer of FO membranes Developer and manufacturer of products and systems for FO applications
Forward Osmosis Technology Osmosis is the flow of water across a semi-permeable membrane from a solution of lower osmotic pressure to a solution of higher osmotic pressure. In general, the higher the dissolved solids concentration, the higher the osmotic pressure. The rate of osmosis is controlled by diffusion of the solutes on both sides of the membrane and within the membrane. FO membranes reject organics, minerals and other solids similar to reverse osmosis (RO) but resist typical fouling problems. Bar = 14.5 psi
Governing Equations for FO Membrane oriented In FO Mode Membrane oriented in PRO Mode Water flux, J w J w = A ( π- P) A water permeability coefficient π osmotic pressure P hydraulic pressure Solute flux, J s J s = B AβRT J w B solute permeability coefficient β van t Hoff coefficient R gas constant T absolute temperature Membrane structure K m = ε D ʈ ɭ D = S K m mass transfer coefficient ε membrane porosity B = D diffusivity ɭ membrane thickness ʈ pore tortuosity S membrane structural parameter Salt rejection, R s B R s = (1+ ) -1 A ( P- π) (1-R s ) A ( P- π) R s *selected images from T.Y. Cath et al. / Journal of Membrane Science 281 (2006) 70 87
FO Sweet Spots and Long Putts Sweet Spots Has no hydraulic pressure requirements Low pressure leads to better performance in fouling systems Highly fouling resistant and easily cleanable (membrane dependent) RO rejection properties (membrane dependent) Long Putts FO transfers water to a solution where it is less thermodynamically favorable to extract the water - energy will be required to get water out Solute loss into the feed solution (rate is solute dependent - for NaCl, this loss is 0.1-1 g / liter of water extracted) The FO process is generally slower vs. the process of RO
Spiral Elements for Commercial and Industrial Water Recycling OsMem Number Useable Membrane Area 8040FO 7.5-18 m² 4040FO 1.5-3 m² 2521FO 0.4-0.8 m² *All designs available with different spacer geometries
Spiral Elements for Commercial and Industrial Water Recycling Spiral elements designed to fit standard low pressure vessels 4 inch and 8 inch diameters. Single to eight element housings.
Sweet Spot Applications The draw solution when osmotically diluted is meant to be consumed by humans (hydrating draw solution). Specifically, a concentrated food syrup can be used to extract water even from seawater and mud puddles. A concentrated stream (e.g., saturated brine) needs to be diluted and a highly fouling wastewater is available - FO becomes a mass exchanger for water (e.g., dilution of hydraulic fracturing fluids for gas and oil production). A stream is so fouling that reverse osmosis (RO) requires either too much cleaning or pretreatment (e.g., landfill leachate). FO becomes an effective RO pretreatment, which is then used to re-concentrate the draw solution and extract the clean water. A product needs to be concentrated that is too fragile for evaporation, (e.g., concentrating grape juice to make a dessert wine, pharmaceuticals ).
Sweet Spot Applications A draw solution is freely available (e.g., seawater for algae concentration or shipboard wastewater concentration). Pressure retarded osmosis - conversion of osmotic potential to electrical energy. Desalination and brine management. osmotic dilution sewer mining Tzahi Cath, Colorado School of Mines Emile Cornelissen KWR The Netherlands SWOsMBR (Seawater Osmotic MBR) pre-filter dirty brine streams before RO (Modern Water) RO retentate management
Hydrating Draw Solution Emergency Preparedness HydroPack TM filled Expedition TM X-Pack TM HTI manufactures and markets a suite of personal hydration water filtration products that meet the needs of various users. These products provide a safe, clean drink for emergency use and survival. unfilled filled
Hydrating Draw Solution Humanitarian Relief Kenyan Demonstration Pilot and later distribution to displaced flood victims in Western Kenya showed the HydroPack: has very high acceptance maintains excellent hydration delivers safe fluids in the field requires little training provides 15x logistics benefit
Hydrating Draw Solution Space Travel Commander Chris Ferguson NASA Emergency Hydration System
Water Mass Exchanger dilution of hydraulic fracturing solutions and the remediation of waste waters generated by exploration Dilute Brine
Water Mass Exchanger dilution of hydraulic fracturing solutions and the remediation of waste waters generated by exploration HTI and its partner Bear Creek Services applied Forward Osmosis technology to create the Green Machine to process gas field wastewater. These systems are mobile, constructed on 54 foot trailers and capable of recycling up to 180,000 gallons of drilling pit waste each day.
RO Pretreatment Remediation of Landfill Leachate Landfill Leachate Treatment 90 to 95% water recovery permeate meets strict EPA standards FO retentate solidified with Portland cement and sent back to landfill (passing TCLP standards)
Concentration of Heat and Shear Sensitive Products Food Concentration at Cold Temps and Low Shear 80% water removal - reducing freeze drying costs by over 60% Nutraceutical Facility Installation Forward Osmosis Plant
Free Draw Solution FO dewatering algae harvested for bio-fuels Floating on the ocean's surface, the forward osmosis pouches will be collecting solar energy as the algae inside produce oxygen by photosynthesis. The algae will feed on the nutrients in the sewage, growing rich, fatty cells. Through osmosis, the bag will absorb carbon dioxide from the air, and release oxygen and fresh water. The temperature will be controlled by the heat capacity of the ocean, and the ocean's waves will keep the system mixed and active. Work currently undertaken by NASA Omega Project. http://lunarscience.arc.nasa.gov/articles/omega When the process is completed, biofuels will be made and sewage will be processed. The goal is to no longer dump sewage directly into the ocean. The algae and nutrients will be contained and collected in the FO bag. Not only will oil be produced, but nutrients will no longer be lost to the sea.
Free Draw Solution - Pressure Retarded Osmosis http://www.statkraft.com/energy-sources/osmoticpower/
Brine Management Sewer Mining (osmotic dilution) Wastewater FO Reconcentration System High quality water Concentrated sewage Renewable energy Digestate Anaerobic digestion
Brine Management Sewer Mining (osmotic dilution) Research conducted by KWR Watercycle Research Institute, The Netherlands (pilot pictured). During trials, FO osmotically diluted the seawater draw by over 50%, (concentrating the waste stream) requiring substantially less operating pressures (less energy) to generate high quality water. http://www.ncbi.nlm.nih.gov/pubmed/22179641
Brine Management Seawater Osmotic Bio-reactor
Brine Management Seawater Osmotic Bio-reactor Forward osmosis plate and frame elements, designed to be immersed in bio-digestate with draw solution (brine) pulled through the membrane sandwich channel. Preliminary results show osmotic concentration of the digestate without membrane performance decline. Osmotic MBR piloting at CSM Draw solution can be seawater, RO retentate, or closed loop brine reconcentration step by RO for high quality water. FO Membrane Plates
Brine Management Seawater Osmotic Bio-reactor Colorado School of Mines, biodigester pilot facility Submerged HTI OsMBR plates Draw solution seawater brine No appreciable flux decline over months (5) Never cleaned air scouring only
Brine Management FO pretreatment of dirty brines prior to RO As reported by Modern Water baseline testing over 5 months with a standard SWRO system resulted in 30% performance decline that was irreversible. When FO operated in front of RO no performance decline over 12 month operations. Draw solution proprietary. Commercial installation - 2011 Modern Water s Plant at Al Khaluf http://www.modernwater.co.uk/assets/pdfs/perth%20sept11%20- %20FO%20Desal%20A%20Commercial%20Reality.pdf
Brine Management RO Retentate Mediation Forward Osmosis water mass transfer diluting the RO retentate to acceptable discharge levels (for both salt ppm and organic contaminants)
Conclusions FO is well suited for applications where: (1) the draw solution, once osmotically diluted, is the end product (hydration drink or frac fluids); (2) high fouling waste water blinds RO (landfill leachate); (3) there is a need for a less aggressive environment to preserve the quality of concentrate (nutraceuticals); and (4) waste minimization with a free draw solution is available (seawater concentrating ship-board wastes). FO shows promise for brine management in the following areas: (1) sewer mining (osmotic dilution); (2) osmotic membrane bio-reactors; (3) pretreating dirty seawater prior to SWRO; and (4) remediation of RO retentate. For successful FO applications the system must take advantage of high osmotic pressure differentials between solutions, generate sufficient fluid dynamics to minimize internal and external concentration polarization, membrane configurations that can be easily cleaned and at the same time compact, modular in design and economical.