Use of Microporous Membranes
 for Compliance with the New
 Drinking Water Regulations

    Peter Hillis, Research Associat...
Introduction

Background
THM
Arsenic
Cryptosporidium
Conclusions
Background

New Drinking Water Directive 98/83/EC
November 1998
THM, As and Cryptosporidium
Question over conventional tec...
Background
decrease in membrane costs
development of higher flux membranes
better understanding of process parameters
auto...
THM

Nanofiltration (NF)
Combined Coagulation and MF or UF
Operational benefits
– increased permeate flux, reduced backflu...
Without Coagulation                  With Coagulation


                      Reduced pore
                      penetrati...
Effect of Coagulation on TMP Development

            100

             90

             80

             70

            ...
90.0%


            80.0%


            70.0%


            60.0%
% Removal




            50.0%


            40.0%


  ...
THM


>80% removal of THM
No floc breakthrough
Enhanced membrane operation
Enhanced membrane performance
Arsenic


Reverse Osmosis
Ion Exchange
Lime Softening
Adsorption on Granular Ferric Hydroxide
Adsorption on Activated Alum...
Effect of pH on As (V) Removal


            120




            100




            80
% Removal




            60


   ...
Arsenic

ferric and aluminium coagulation can remove
As (V)
The removal by aluminium sulphate is clearly
related to the pH...
% Removal of As (V) at Different Ferric Chloride Doses at pH 7

            120




            100




             80
% ...
% As (III) Removal for Alum and Ferric Chloride

            100


             90


             80


             70
% R...
Process schematic for combined coagulation and MF or UF
for arsenic removal


    Coagulant pH 7
                         ...
Arsenic

As (V) more readily removed than As (III)
As (III) not removed by Aluminium Sulphate
Pre-oxidation will enhance r...
Cryptosporidium

Conventional treatment processes are
susceptible to the passage of Cryptosporidium
into the drinking wate...
Principles of Operation of Immersed Membrane

                         Permeate
                                         R...
The ZeeWeed® Hollow Fibre
The ZW-4000
ZeeWeed® Cassette


   Surface area: 370 m2

   Dimension:
          Height: 180 cm
          Width: 60 cm
   ...
USF Memcor CMF-S

        Filtrate manifold



         Clover



       Modules
USF Memcor CMF-S



               Liquid backwash
             plus air scour within
             membrane module
Key Benefits Drinking Water

Retrofitting / upgrading existing plants by
 immersion of the membranes in clarifiers
 or san...
Conclusions

Microporous membranes can be used to ensure
that companies comply with the changes under
the new drinking wat...
Conclusions

Performance associated with much higher
pressure driven processes can be achieved using
low-pressure     memb...
Summary

Question over RGF efficacy - ripening,
breakthrough and transience (flow changes)
MF/UF offer a more secure barri...
Use Of Microporous Membranes For Regulatory Compliance
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Use Of Microporous Membranes For Regulatory Compliance

  1. 1. Use of Microporous Membranes for Compliance with the New Drinking Water Regulations Peter Hillis, Research Associate, North West Water Ltd
  2. 2. Introduction Background THM Arsenic Cryptosporidium Conclusions
  3. 3. Background New Drinking Water Directive 98/83/EC November 1998 THM, As and Cryptosporidium Question over conventional technologies Ultrafiltration (UF) and Microfiltration (MF) membrane technologies
  4. 4. Background decrease in membrane costs development of higher flux membranes better understanding of process parameters automation potential simplicity of operation more stringent water quality requirements, e.g. Cryptosporidium
  5. 5. THM Nanofiltration (NF) Combined Coagulation and MF or UF Operational benefits – increased permeate flux, reduced backflushing, reduced chemical cleaning eliminating the penetration of colloidal material into the pores modification of the deposit characteristics
  6. 6. Without Coagulation With Coagulation Reduced pore penetration More porous cake
  7. 7. Effect of Coagulation on TMP Development 100 90 80 70 60 TMP (kPa) 50 No Coagulation With Coagulation 40 30 20 10 0 0 1 2 3 4 5 6 7 8 Days Run
  8. 8. 90.0% 80.0% 70.0% 60.0% % Removal 50.0% 40.0% 30.0% 20.0% %Removal THMFP %Removal TOC 10.0% 0.0% 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 Coagulant dose (mM Fe)
  9. 9. THM >80% removal of THM No floc breakthrough Enhanced membrane operation Enhanced membrane performance
  10. 10. Arsenic Reverse Osmosis Ion Exchange Lime Softening Adsorption on Granular Ferric Hydroxide Adsorption on Activated Alumina Coagulation
  11. 11. Effect of pH on As (V) Removal 120 100 80 % Removal 60 Alum (0.06mM) 40 Fe (0.03mM) 20 0 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 pH
  12. 12. Arsenic ferric and aluminium coagulation can remove As (V) The removal by aluminium sulphate is clearly related to the pH iron (III) hydroxide is able to operate over a much wider pH range
  13. 13. % Removal of As (V) at Different Ferric Chloride Doses at pH 7 120 100 80 % Removal 60 40 20 0 0.000 0.020 0.040 0.060 0.080 0.100 0.120 0.140 Metal Concentration (mM as Fe)
  14. 14. % As (III) Removal for Alum and Ferric Chloride 100 90 80 70 % Removal 60 % Rem Fe (pH 7) 50 % Rem Al (pH 7) 40 30 20 10 0 0 0.05 0.1 0.15 0.2 Metal Concentration (mM)
  15. 15. Process schematic for combined coagulation and MF or UF for arsenic removal Coagulant pH 7 MF or UF Treated Water Pre-oxidation Flocculation Waste
  16. 16. Arsenic As (V) more readily removed than As (III) As (III) not removed by Aluminium Sulphate Pre-oxidation will enhance removal Chlorine, ozone or permanganate A significant concern for any arsenic removal process is waste disposal for arsenic-laden sludges
  17. 17. Cryptosporidium Conventional treatment processes are susceptible to the passage of Cryptosporidium into the drinking water supply MF and UF offer significant advantages due to barrier nature of the processes
  18. 18. Principles of Operation of Immersed Membrane Permeate Recovery QF Feed Qf QF − QP Y= Immersed QF membranes Qbp Membrane tank Air QP injection Purge
  19. 19. The ZeeWeed® Hollow Fibre
  20. 20. The ZW-4000 ZeeWeed® Cassette Surface area: 370 m2 Dimension: Height: 180 cm Width: 60 cm Depth: 160 cm Packing density: 210 m2/m3
  21. 21. USF Memcor CMF-S Filtrate manifold Clover Modules
  22. 22. USF Memcor CMF-S Liquid backwash plus air scour within membrane module
  23. 23. Key Benefits Drinking Water Retrofitting / upgrading existing plants by immersion of the membranes in clarifiers or sand filters or contact tanks or backwash holding tanks
  24. 24. Conclusions Microporous membranes can be used to ensure that companies comply with the changes under the new drinking water regulations Combining coagulation with either a MF or UF system can enhance their performance in terms of their removal capabilities
  25. 25. Conclusions Performance associated with much higher pressure driven processes can be achieved using low-pressure membrane processes by combining coagulation with MF or UF The barrier nature of MF and UF membranes combined with removal of contaminants with coagulation means that multiple drivers can be met in on stage
  26. 26. Summary Question over RGF efficacy - ripening, breakthrough and transience (flow changes) MF/UF offer a more secure barrier Technology is maturing Recent innovations make further adoption more likely

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