Operating parameters influencing Ultrafiltration of organic model solutions

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1 Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Operating parameters influencing Ultrafiltration of organic model solutions Verónica García Molina Technical Service and Development Dow Water Solutions th November, Aachen

2 Aquabase Workshop on Mitigation Technologies Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November STRUCTURE OF THE TALK Overview Ultrafiltration Experimental Results Conclusions

3 PRINCIPLES OF ULTRAFILTRATION What is Ultrafiltration? Aquabase Workshop on Mitigation Technologies Ultrafiltration is a size exclusion membrane process that reject particles, pathogens, high molecular weight species, and ultimately lower turbidity. However, UF does not reject any dissolved salts, dissolved organics, or other species like true color, taste & odor, etc.

4 PRINCIPLES OF ULTRAFILTRATION What is Ultrafiltration? Aquabase Workshop on Mitigation Technologies ionogen molecular macro molecular micro particle macro particle aqueous salts carbon black paint pigment human hair synthetic dye albumin protein tobacco smoke yeast cells beach sand metal ion sugar endotoxin viruses gelatin bacteria indigo blue red blood cells Pollen activated carbon atomic radius latex / emulsion asbestos milled flour Relative size of common materials d P [µm] UF 1000

5 Aquabase Workshop on Mitigation Technologies PRINCIPLES OF ULTRAFILTRATION Why UF? Ultrafiltration membrane development has been accelerated due to more stringent drinking water rules around the world to remove pathogens from drinking water coupled with its potential of easy integrity validation. Pathogens Rotavirus [bar = 100 nm) F.P. Williams, U.S. EPA Cryptospridium and Giardia [bar = 10 µm] H.D.A Lindquist, U.S. EPA E. Coli Microcolony average cell is ~ 4 µm long James Shapiro and Clara Hsu, University of Chicago Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

6 Aquabase Workshop on Mitigation Technologies PRINCIPLES OF ULTRAFILTRATION Operation mode: Dead-end vs Cross-Flow Feed Feed Concentrate membrane membrane Permeate Permeate Module Application Dead-End Hollow fiber (submerged and pressurized) Feed TDS Spiral wound Feed TDS Cross-Flow Operation Cleaning Drawbacks Discontinuous operation Back wash feasible Flux decline or feed pressure increase with time Continuous operation Back wash not possible With high TDS, higher feed spacer required

7 Aquabase Workshop on Mitigation Technologies PRINCIPLES OF ULTRAFILTRATION While working in Dead-End modus: Backwash (Reverse Filtration) o Often dosed with 15 ppm of NaClO (fouling control) o Flowrate is 200% of design flux (minimum 100 lmh) Air Scrub o Air pressure is <1 bar delivered at the module o Frequency is typically every 6 hours when necessary Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

8 Aquabase Workshop on Mitigation Technologies PRINCIPLES OF ULTRAFILTRATION While working in Dead-End modus: Chemically Enhanced Back-wash (approx. Every 72 hours) Acid: HCl 1000 ppm Removes colloids and inorganic salt Alkali: NaOH 500 ppm or NaClO 1000 ppm Removes organics or biofoulants from membrane Clean in Place (every 1 to 3 months) Acid: HCl 2000 ppm ;ph 2 Alkali: NaOH 1000 ppm or NaClO 2000 ppm; ph12 Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

9 PRINCIPLES OF ULTRAFILTRATION Aquabase Workshop on Mitigation Technologies Main fields of applications of Ultrafiltration? Municipal and industrial wastewater treatment and reuse Membrane Bioreactors Hygienization of WWTP Pre-filter before NF/RO Drinking water processing Pre-treatment for NF/RO Surface water treatment for industrial use Food industry Pharmaceutical industry Metal processing industry Seawater pretreatment

10 PRINCIPLES OF ULTRAFILTRATION CASE 1 Petrochemical Water Reclamation Source: Petrochemical plant wastewater Capacity: 560 m3/h Location: Beijing, China Running Time: From 2005 Process: UF Pretreatment UF RO DI Item CODcr(mg/L) Amount 40 Turbidity(NTU) 5.0 Oil(mg/L) NH 3 -N(mg/L) TSS(mg/L) TDS(mg/L) Ca 2+ (mg/l) UF Feed Water Quality High COD UF COD removal 37.5% Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

11 PRINCIPLES OF ULTRAFILTRATION CASE 2 Microelectronics Water Reclamation Source: Plant industrial wastewater [from cut and grind process] Capacity:90 m3/h Location: Shanghai, China Running Time: From 2006 Process: Coagulation Sedimentation Bag Filter UF Parameter Unit Feed water ph 7.5 Turbidity NTU 4847 CODcr mg/l 1122 TDS mg/l 69.1 (15.5 ) Actived Silica mg/l 82.9 Total Silica mg/l 91.6 Oil mg/l 0.08 High turbidity High COD value Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

12 PRINCIPLES OF ULTRAFILTRATION CASE 3 High TSS Surface Water Treatment Operational Performance Feed 2 ppm NaOCl before UF System Process: Raw Water Tank UF Feed Pump Heater Exchanger OMEXELL TM UF RO High TSS raw water feed to OMEXELL TM UF directly Turbidity is less than 0.4 NTU (100%) and less than 0.2 NTU (90%) TMP is less than 0.5 bar (average) CIP is only once during 2 years operation

13 PRINCIPLES OF ULTRAFILTRATION CASE 3 Seawater Pretreatment Source: Seawater Capacity: 50,000 m3/d UF Permeate and 28,800 m3/d RO Water Location: HeBei, China Running Time: From 2005 Process: Disc-Filter + UF + RO TMP is less than 0.4bar Without CEB BW Frequency: >30min CIP Frequency: Once/3~4months

14 Aquabase Workshop on Mitigation Technologies Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November STRUCTURE OF THE TALK Overview of Ultrafiltration Experimental Results Objective Experimental Device Discussion of results Conclusions

15 EXPERIMENTAL PART Objective: Aquabase Workshop on Mitigation Technologies Study the influence of some operating parameters on the performance of an UF test unit Concentration of solutes in the Feed Pressure Applied ph of the solution Presence of Calcium

16 EXPERIMENTAL PART Ultrafiltration Test Cell Aquabase Workshop on Mitigation Technologies Stirrer Membrane Pressurized air conduction Feed and concentrate Permeate Volume Membranes Solution Agitation Pressure Temperature Duration 400 ml 30 kda (cellulose), 20 kda and 5 kda (polyethersulfone) Dextran, Humic Acid, Fulvic Acid, NOM, Cellulose powder, Alginic Acid 300 rpm 1 3 bar Ambient Until a certain amount of permeate is collected

17 EXPERIMENTAL PART Aquabase Workshop on Mitigation Technologies Influence of the solute concentration in the feed solution Permeability (L/m 2 hbar) Permeate Volume (ml) 1 mg/l 3 mg/l 5 mg/l 8 mg/l 10 mg/l 65 Permeability (L/m 2 hbar) Permeate Volume (ml) 30 kda Cellulose membrane 20 kda Polyethersulfone membrane Permeability vs. Permeate volume. Dextran solutions containing from 1 to 10 mg/l High concentrations higher membrane fouling/cake layer formation

18 EXPERIMENTAL PART Aquabase Workshop on Mitigation Technologies Influence of the solute concentration in the feed solution - Concentration + Concentration Feed Feed Feed membrane membrane membrane Permeate Permeate Permeate High concentrations higher membrane fouling lower flow

19 EXPERIMENTAL PART Aquabase Workshop on Mitigation Technologies Influence of the solute concentration in the feed solution kda 20 kda 30 kda Membrane - Concentration + Concentration Retention Re tention Dextran Concentration (mg/ml) 30 kda membrane Cake layer model: Concentration Passage COD = 1 COD permeate feed 20 kda Membrane - Concentration + Concentration 20 kda membrane Difussion Model: concentration difference Passage

20 EXPERIMENTAL PART Aquabase Workshop on Mitigation Technologies Influence of the transmembrane pressure Flux (ml/m 2 h) 33 1 bar 2 bar 3 bar Permeate Volume (ml) Flux vs. Permeate volume. 10 mg/l of Fulvic Acids solutions. 5 kda Polyethersulfone membrane Higher transmembrane pressure results in higher permeate production Retention values after UF of solutions containing NOMs and Dextran NOM 1R101N (10 mg/ml) 5 kda NOM 1R108N (10 mg/l) 5 kda Dextran (3 mg/ml) 30 kda 1 bar 2 bar 3 bar Higher transmembrane pressure results in faster accumulation of solutes higher passage COD Retention= 1 COD permeate feed

21 EXPERIMENTAL PART Aquabase Workshop on Mitigation Technologies Influence of the ph of the feed solutions Flux (ml/m 2 h) 64 ph 4.8 ph 6 ph 8 ph Permeate Volume (ml) Zeta Potential [mv] Measured Values Average ph Flux vs. Permeate volume. 3 mg/l of Dextran solutions at different ph conditions. 30 kda Cellulose membrane The higher the ph: -The membrane is more negatively charged - Dextran more negatively charged due to deprotonation

22 Aquabase Workshop on Mitigation Technologies EXPERIMENTAL PART Influence of the presence of Ca 2+ in the feed solution Flux (L/m 2 h) g/l Alginic Acid 3 g/l Alginic Acid mg/l CaCl 2.2H 2 O Permeate Volume (ml) Bridging characteristics of Ca 2+ between: -Solute Solute -Solute - Membrane Fastest formation of a fouling layer on the surface of the membrane; Flux vs. Permeate volume. 5 kda Polyethersulfone membrane Higher resistance for the water Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November

23 Aquabase Workshop on Mitigation Technologies Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November STRUCTURE OF THE TALK Overview of Ultrafiltration Experimental Results Conclusions

24 CONCLUSIONS Aquabase Workshop on Mitigation Technologies Conclusions Flux decline during UF operation still remains an issue for its further development Concentration in feed, applied pressure, ph and presence of divalent cations have been proved to have a direct influence on the process Membrane selection plays a crucial role for the success of the process

25 Aquabase Workshop on Mitigation Technologies Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow Verónica García Molina, Aachen 27-28th November THANK YOU VERY MUCH FOR YOUR ATTENTION