Membrane Distillation for Desalination and Resource Recovery: Demonstrations with Industry

Transcription

1 Membrane Distillation for Desalination and Resource Recovery: Demonstrations with Industry Dr Nicholas Milne Institute for Sustainability and Innovation, Victoria University, Melbourne, Australia 17 th February 2015 ACS Poly Workshop, Pacific Grove, USA Background image courtesy of dan /FreeDigitalPhotos.net

2 Acknowledgements Noel Dow Kennedy Kesieme Tom O Rielly Eddy Ostarcevic Dr Jianhua Zhang Dr Xing Yang Dr Angela Hausmann Prof Mikel Duke Prof Stephen Gray Prof Hal Aral Lesley Naidoo Sandip Ranjan Jesus Villalobos Garcia (L Universite Toulouse III Paul Sabatier) Audra Liubinas Paul Atherton Dr Chuyong Cheng

3 Industry heat as a resource Membrane distillation has a clear niche market in the water treatment arsenal. Most useful where waste heat is available

4 Industry heat as a resource Membrane distillation has a clear niche market in the water treatment arsenal. Most useful where waste heat is available Suited for operation where reverse osmosis and nanofiltration cannot operate. More interest in treating challenging waters

5 Industry heat as a resource Various industries (foods, manufacturing, chemicals, etc.) use thermal energy Can we get more value from it? convert waste water to clean water Examples (heat from cooling tower or heat exchanger) 2MW (small/medium industry) 40,000 to 480,000 litres per day (one 8m lap pool to 7 large residential swimming pools/day) 500MW (large industry e.g. power station) 10 to 120 million litres per day (4 to 48 Olympic swimming pools/day) Membrane distillation can convert this heat to treated water x48/day

6 Membrane Distillation Temperature difference drives the process. Water passes through the membrane as a vapour. Rejection is higher than RO and can outperform other thermal techniques. Cl - Na + Vapor Membrane distillation relies on the hydrophobicity of the membrane for rejection. Vapor Hydrophobic Membrane

7 Membrane Distillation If hydrophobicity is compromised, membrane wets, salt passage occurs. Cl - Na + Vapor Hydrophobic Membrane

8 High performance membranes Heat and mass transfer studied within and around various membranes. Membrane structure and support layers greatly impacted performance. Best performing membrane: Hydrophobic polytetrafluoroethylene (PTFE) Scrim (woven) support Supplied by Ningbo Changqi, China Support Membrane J. Zhang, et al, (2010) J. Memb Sci, v362, p J. Zhang, et al, (2010) J Memb Sci, v349 p. 295.

9 Flux (kg/m 2 /h) Applications water treatment Industry waste survey Inland groundwater brine reduction Permeate Flux (L/m2/hr) % Recovery Feed concentration [11,000 mg/l - 247,000 mg/l] Feed concentration [26,000 mg/l - 283,000 mg/l] Feed concentration [30,000 mg/l - 361,000 mg/l] Time (hr) Time (mins) IX regeneration waste from PS Suitable for pilot trial Concentrate to nearly saturated NaCl Suitable for pilot trial N. Dow et al, AWA Water, Sept U.K. Kesieme et al, (2013) Desalination, v323, p66

10 Applications acid recovery For non-volatile acid (H 2 SO 4 ) H 2 SO 4 waste solutions For volatile acids (HCl) HCl waste solutions DCMD fitted with a Filter H 2 O Concentrates- Acid, Metals DCMD fitted with a Filter Concentrates- Metals Permeate -HCl To metal recovery Solvent Extraction Stripped organic Flow sheet to recover HCl from HCl loaded waste solution Stripping (H 2 O) H 2 SO 4 Flow-sheets to recover H 2 SO 4 and water from H 2 SO 4 loaded waste solutions U. K. Kesieme et al. (2013) Hydrometallurgy v138, p14 U.K. Kesieme et al. (2014) Water Sci Technol, v69, p. 868.

11 Volatile HCl recovery: Applications acid recovery Species Al Co Cu Fe Mg Mn Ni Sc Zn Initial Feed [mg/l] Final Feed [mg/l] Final Permeate [mg/l] Non-volatile H 2 SO 4 recovery: Free H + [mol/l] < <0.1 <0.1 <0.1 < Species Al Ca Co Cu Fe Mg Mn Ni Sc Zn Initial Feed [mg/l] Final Feed [mg/l] Free H + [mol/l] HCl driven off with increasing concentration 3 stage SX: 99% acid extraction U.K. Kesieme, et al. (2014) Water Sci Technol, v69, p. 868.

12 Pilot trials and commercialisation 2008 Bench Test 2009 Mark I Solar field Cooler MD plant M. Duke, et al,. (2009) OzWater 09. p Mark III 2011 Mark II N. Dow, et al. (2010) in OzWater'10. p. 036 VU-ATM Project N. Dow, et al,. (2012) OzWater'12. Two patents MD technology license under negotiation

13 Textiles, mineral processing, storage and treatment lagoons all can be impacted by surfactants Rising Challenge

14 Mark II pilot Textile waste water Textile waste water AusIndustry project with Australian Textile Mills Standard PTFE Flux: 17 L/m 2 /h Not tolerant to surfactants Laminated PTFE Flux: 5.2 L/m 2 /h >80% water recovery Worked well with surfactants Acknowledgement: Jesus Garcia and Leslie Naidoo

15 Liquid Entry Pressure

16 Liquid Entry Pressure LEP for a solution known to quickly wet was 80 kpa Surfactant impact on LEP is not the only mechanism which compromises a membrane

17 Time to Wetting Change to constant pressure (~ 90 kpa) applied by vacuum and measure passage with time Time to first sign of passage (mins) Effluent 8 Effluent diluted to 50% 10 Effluent diluted to 25% 20 Pre-Treated Effluent >40

18 Lab Scale MD for Estimations P = 20 kpa

19 Pre-Treatments Raw Water Diluted Raw Water Fractionation Ozonation

20 Pre-Treatments Water Source Wetting Capability (µs/hr) Raw Water % Diluted 20 Foam Fractionation 10 Ozonation 24 Fenton Oxidation 16 Biological Treatment (CAS) 2 Biological Treatment (3 days) 14

21 Fenton Oxidation + Fractionation

22 Fenton Oxidation + Fractionation

23 Fenton Oxidation + Fractionation t (mins) Permeate SO 2-4 (mg/l) Permeate TOC (mg/l) Wetting was not occurring, volatile transfer was. Masked in original solution by fouling Product of the chemical pre-treatment

24 Mark III Pilot Textile waste water Australian Textile Mills, Wangaratta Proof of industrial viability (performance and application) VU s Mark III module Multilayer design More area per layer Simplified connections Part of the full solution MD integrated to harness heat to treat saline waste water

25 Mark III Pilot Textile Waste Water Flux was not what was anticipated recirculating rate was insufficient. Flux was initially quite variable effectively no control over rate of heat transfer, feed temperature varied wildly. Both engineering issues that can be corrected.

26 Mark III Pilot Textile Waste Water Conductivity was not a sufficient measurement. Wetting only appeared to occur towards the end of the trial. Need for corrective action taken from sulphate.

27 Conclusions MD is a emerging tool in the desalination arsenal that is ideally suited to areas where waste heat is readily available and desalination would otherwise be challenging. Piloting and scale-up has been proving successful, while there are some engineering challenges, these are not insurmountable. Minor components is water chemistry play an important role in the results we observe it is important to understand and monitor even for compounds that aren t expected. Use this knowledge to then better understand how to apply the technique in real life situations.

28 9 th International Membrane Science and Technology Conference (IMSTEC) 2016, Adelaide, Australia 4 th -9 th December,