OMBReuse: Osmotic processes for water recycling

Transcription

1 OMBReuse: Osmotic processes for water recycling G. Blandin 1, J.Comas 1,2, I. Rodriguez-Roda 1,2, 1 LEQUIA, Institute of the environment, University of Girona, Spain 2 ICRA, Catalan Institute for Water Research, Girona, Spain

2 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

3 What are osmotic processes? Feed solution Draw solution To extract and purify water from the feed solution To concentrate the feed solution At low/ no energy cost!

4 Examples of highly osmotic solution Potential sources of energy /driving forces!

5 Applications Food concentration Fertigation Microalgae No thermal or high pressure treatment: Keep the taste! Fertiliser used to attract impaired water for dilution before spreading!

6 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

7 Water treatment Difficult to treat water! Draw recovery

8 Water reuse: combined with SW desalination First study on FO: Cath et al. (JMS362, 2010) Lower energy for seawater desalination thanks to the osmotic dilution Beneficial reuse of wastewater, i.e. water recycling Multi-barrier protection to increase consumer confidence in water recycling Reduction in reverse osmosis membrane fouling Main limitation: colocation of wastewater and desalination plant (costal area)

9 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

10 OMBReuse Tecniospring program : Marie Curie and Tecniospring fellowship (2 year post-doc, sept ) Catalan - EU Co funding, focus on technology transfer Objective: To optimize osmotic membrane bioreactor (OMBR) to render it economically attractive while assuring a water quality satisfying drinking water standards to support water reuse scheme.

11 What is OMBR? OMBR=MBR where the driving force for water permeation is an osmotic gradient! RO Current limitations of OMBR Commercial submerged modules still in development Low flux of FO membrane Salinity build up in the sludge reactor How does it compare with MBR (OMBR-RO vs. MBR-RO)?

12 Main ojectives: Design and tests of OMBR modules: 1. To optimise the flux 2. With novel TFC FO membrane OMBR operation 1. Permeation flux 2. Salinity build up 3. Fouling /cleaning 4. Membrane resistance/degradation 5. Rejection of trace organic contaminants (TrOCs)

13 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

14 OMBR modules Plates design and scale-up Hollow fiber modules

15 Design of OMBR plates: OMBRetrofit Based on Plate and frame design (Kubota frames) MBR OMBR Concept of MBR retrofitting in OMBR European patent filled in June 2016 on retrofitting MBR systems into OMBR

16 Towards higher flux/lower draw concentration: 40 1st prototype Water flux (L.m -2.h -1 ) MBR range of operation Most OMBR studies (HOLLOWAY et al., 2015) Draw concentration (g/l)

17 Towards higher flux/lower draw concentration: 40 1st prototype Water flux (L.m -2.h -1 ) nd prototype MBR range of operation Most OMBR studies (HOLLOWAY et al., 2015) New TFC membrane Draw concentration (g/l)

18 Towards higher flux/lower draw concentration: 40 1st prototype 2nd prototype Water flux (L.m -2.h -1 ) rd prototype MBR range of operation Most OMBR studies (HOLLOWAY et al., 2015) Improved design Draw concentration (g/l)

19 Towards higher flux/lower draw concentration: 40 Cross flow cell 1st prototype 30 2nd prototype Water flux (L.m -2.h -1 ) rd prototype MBR range of operation Most OMBR studies (HOLLOWAY et al., 2015) Still some room for improvement! Draw concentration (g/l)

20 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

21 50L MBR/OMBR pilot testing 50L reactor (anoxic/aerobic tanks, recirculation loop) Synthetic influent MLSS: 8-10 g.l -1, HRT: 1 day, SRT: >30days Control: flux, TMP, conductivity, ph, removal (COD, N, P) Combined MBR/OMBR operation MF plate Kubota, 2 TFC FO commercial membranes Similar flux 10LMH! 21

22 Salinity build up in combined MBR/OMBR Limited increase of salinity thanks to the salt purge by MBR But: Flux decrease with salinity increase in the mixed liquor: ECP Operating at higher (even moderate) salinity is also detrimental to the flux! 22

23 Fouling / cleaning Fouling occurrence Osmotic backwash After cleaning FO MF Chemical cleaning NaClO Easier removal of fouling layer with FO 23

24 Membrane degradation: loss of selectivity 20 2,0 Jw (L.m-2.h-1) ,5 1,0 0,5 Js/Jw (g/l) 0 Before After Before After 0,0 TFC1 TFC2 Both membranes tested: Limited loss of water flux but significant loss of selectivity! Autopsy/ SEM: physical damage, degradation of the selective layer 24

25 Rejection of trace organic contaminants 100% 80% 60% 40% Rejection 20% 00% -20% -40% FO TFC1 FO TFC2 MF Kubota -60% High rejection of all coumpounds (TFC1>90%) FO TFC1>FO TFC2 >>MF 25

26 Summary 1. What are osmotic processes? 2. Osmotic processes in water treatment 3. OMBReuse /what is OMBR? 4. Design of OMBR modules 5. OMBR operation 6. Conclusion /next step

27 Conclusions Main conclusions High rejection of OMBR: valuable in the context of potable water reuse (even combined with desalination) Possible to reach higher flux than 10LMH with low salinity draw solution (economically competitive vs MBR-RO) But standalone OMBR will be challenging (need salt purge, MBR membrane): preferred MBR/OMBR combined operation and OMBRetrofit Conclusion /next step Next steps: To further improve process design and operation Longer term /larger scale validation Large scale pilot in a WWTP 2017 Full scale trial ~2018 Get more insights of membrane degradation phenomena 27

28 Thanks Acknowledgements More informations BLANDIN, G., COMAS, J. & RODRIGUEZ-RODA, I Proyecto OMBReuse, biorreactores de membrana osmóticos para la reutilización de agua. RETEMA. BLANDIN, G., COMAS, J. & RODRIGUEZ-RODA, I. Potential and Challenges of Osmotic Membrane Bioreactor (OMBR) for (Potable) Water Reuse: A Pilot Scale Study. Frontiers International Conference on Wastewater Treatment and Modelling, Springer, BLANDIN, G., VERLIEFDE, R. A., COMAS, J., RODRIGUEZ-RODA, I. & LE-CLECH, P Efficiently Combining Water Reuse and Desalination through Forward Osmosis Reverse Osmosis (FO-RO) Hybrids: A Critical Review. Membranes, 6. BLANDIN, G., LE-CLECH, P., CORNELISSEN, E., VERLIEFDE, R. A., COMAS, J. & RODRIGUEZ-RODA, I. Can osmotic membrane 28 bioreactor be the next solution for water reuse?, perspective paper in npj clean water, (submission 06/2017)