Recent Advances in Membrane Technologies Peter D Adamo, Ph.D., P.E Spring Conference Wilmington, NC April 13, 2015

Transcription

1 2015 Spring Conference Wilmington, NC April 13, 2015 Recent Advances in Membrane Technologies Peter D Adamo, Ph.D., P.E HDR, Inc., all rights reserved.

2 Membrane Filtration Basics Recent Membrane Advances Operational Considerations Conclusions

3 Membrane Filtration Basics

4 Membranes vs. Granular Media Membrane filtration mechanism o Sieving/Straining Granular media filtration mechanism o Interception, collision, electrostatic attraction

5 Membrane Classifications (Pore Size, microns) Visible to naked eye Organic Macromolecules Colloids Bacteria Viruses Dissolved Salts Yeasts 10 Ultrafiltration Microfiltration Organic Compounds Red CryptosporidiumSmallest globule microorganisms Sand Filter ~ Polio virus Reverse Osmosis Nanofiltration

6 Membranes Classification (Driving Force) Vacuum (Submerged Membranes) o Compatible with Higher Solid Concentration o Can Be Used for Retrofit o Higher Energy Demand with Air Scouring o Noise, Corrosion & Evaporation Concerns

7 Membranes Classification (Driving Force) Pressure (Canister Membranes) o More Compact Design o High Solid Concentrations Problematic (> 100 NTU) for a Substantial Period of Time

8 Membranes Classification (Configuration) Polymeric Material (polyethersulfone (PES) or polyvinylidene difluoride (PVDF), others) Hollow Fiber Membranes (ID < 1.5 mm) Mostly used in MF & UF

9 Flux Cleaning Operational Considerations

10 Typical Pressure MF/UF System Permeate Air System B/W Water Cl 2 Finished Water Pumping Raw Water Source Supply Pump Pretreatment Particle Strainer Membrane Modules Backwash Waste/ Concentrate Finished Water Storage CIP System To Disposal

11 Submerged - Enhanced Coagulation Feed Water Coagulant Flash Mixer Pretreatment Permeate Pump Flocculation Chamber Bleed/Concentrate Air CIP System

12 Key Membrane Terminology Flux Flow across Membrane (gallons/sf/day, GFD) Temperature Corrected Flux (Standard 20-degree C) Transmembrane Pressure Water Pressure Change across Membrane, TMP) Specific Flux Flux/TMP Specific Permeability Filtrate flow/(membrane area * TMP) Integrity Testing (Pressure Decay Test, Bubble Point Test) LRV Log Removal Value

13 Membrane Cleaning Hydraulic Cleaning (every 15 to 45 minutes) Maintenance Wash (every 12 to 48 hours) Clean-in-Place (every 4 to 8 weeks) Water/Air Backwash Air Scouring Water Flushing Hypochlorite or citric acid Chemical recirculation Water Flushing Hypochlorite and Citric Acid Acid/Base Proprietary Chemicals (surfactants)

14 Membrane Fouling Pressure - psi Backwash Membrane Fouling Backwash & Chemical Cleaning Irreversable Fouling Time

15 Recent Membrane Advances

16 Membrane Fiber Breakage Management When will fibers break? o During shipment, installation, o start-up and operation Why will fibers break? o Fibers dried out o Mechanical abrasion o Embrittlement o Abrading each other o Debris (raw water or backwash water) o Poor quality

17 Changes to Membrane Designs Materials of construction Configuration

18 Materials of Construction (Polymeric) Polymeric membranes o Improved chemistry for slightly better chemical resistance o Enhanced permeability o Larger diameter fibers with thicker walls to resist fiber breakage o Some vendors have changed potting materials Pall Microza GE Zenon Common Municipal Membrane Vendors Evoqua (Siemens) Memcor N Modules None really Recent Changes Thicker fibers for ZW-1000 New modules for ZW-1500 system Thicker fibers New potting materials

19 Advancements in Permeability and Abrasion Resistance Research shows membrane permeability of a membrane fiber directly correlates to abrasion resistance of the membrane fiber Evoqua N Fiber after 1 month of harsh, accelerated abrasion testing Little visible evidence to suggest degradation

20 Improved Fiber Morphology Drives System Improvements

21 Yuba City Water Treatment Plant - First Two Years of Operation Summary Membrane permeability remained high Treated water quality was excellent Pressure decay test values began to rise and log removal values fell Membrane integrity issues became a concern and Memcor was contacted Memcor began pilot testing in 2010 to gain understanding of problem

22 Pilot Testing Summary Pilot testing of the originally installed S10V modules conducted August 2010 through June 2011 Pilot unit experienced same integrity issues as the full scale system Cause identified as abrasion of the fibers by small particles such as diatoms, which compromised the outer surface of the fibers Pilot testing of the new S10N UF modules conducted August 2011 through June 2012 Pilot unit modules showed dramatic improvement in integrity TMP remained low and permeability high throughout the test period

23 Pilot Testing Results for N Module at Yuba City

24 Integrity Testing Results for N Module at Yuba City

25 And with the Resulting Permeability Enhancement a Reduction in Pumping Requirements

26 inge Multibore Membranes Polymeric MF membranes with large, multiple lumens in one fiber Improved physical strength (no fiber breakage) Tolerate high turbidity

27 What are Ceramic Membranes? Aluminum oxide porous base material Often used for difficult industrial applications System for potable water developed by NGK, Japan in 1990s Very expensive but nearly indestructible o Less pre-treatment requirements o ph, oxidant resistant Very low O&M costs o Membranes last 50+ years

28 Ceramic versus Polymeric Monolith Variable Ceramic Polymeric Flux (gfd) Turbidity (NTU) < 1,500 <100 TSS (mg/l) < 3,000 < 200 TOC/DOC (mg/l) < 100 < 30 Coagulant (mg/l) < 200 < 30 Recovery (%) > 98 > 96 1,000 s of HF lumens Filtration Interval (hrs) CEB Interval (day) CIP Interval (month) 6 1

29 Ceramic Membrane process train requires less pretreatment ClO 2 or KMNO 4 Coagulant Chlorine Deer Creek PS PAC Influent Tank (Aeration/PAC) Flocculation Ceramic Membranes BWW GAC UV (Future) Clearwell Effluent

30 35 Ceramic Membranes are Robust and Becoming more Cost Effective Ability to handle high turbidity, PAC and coagulants 20-year membrane warranty New Dutch design improves economics

31 Pall Kruger Siemens Membrane Pre-Selection Procurement Bid Tabs Line Item Costs by Membrane Manufacturer Total Membrane System Capital Cost Total Membrane Plus Pretreatment Capital Cost (Tax Included) Total of Annual Operating Costs (Present Worth) 20-Year Present Worth of Annual Cost For Membrane Replacement Pretreatment Present Worth O&M Total 20-Year Present Worth Total $1,383,828 $3,088,188 $1,172,569 $2,078,658 $3,170,125 $1,867,399 $1,729,076 $737,577 $1,667,222 $260,211 $265,139 $516,072 $493,206 $362,067 $499,461 $4,561,150 $4,534,908 $4,550,154

32 Take Away Points Membranes Offers a Wide Range of Applications Membrane is a Mature Technology but New Advances Every Year Industry Moving more Towards Plug and Play A Successful Membrane Operation Depends on o The Selection of an Appropriate System o Proper Pretreatment for water supply and technology

33 Questions? 2014 HDR Architecture, 2014 HDR, Inc., all rights reserved.