Application of Electrodialysis Reversal (EDR) Membrane Technology in Drinking Water Treatment Plant to Supply the Metropolitan Area of Barcelona

Transcription

1 Application of Electrodialysis Reversal (EDR) Membrane Technology in Drinking Water Treatment Plant to Supply the Metropolitan Area of Barcelona Pere Emiliano Estapé. R+D+i Technician (ATLL) Fernando Valero Cervera. R+D+i Manager (ATLL)

2 Introduction 1

3 ATLL Concessionària de la Generalitat de Catalunya SA Water supply of 4,5 million people 2+1 Drinking Water Treatment Plants (DWTP) Ter Llobregat Llosa del Cavall 1+1 Seawater Reverse Osmosi (SWRO) Llobregat Blanes Distribution system km Φ 200 to mm Retention times, 1h to 72h 2

4 Llobregat Drinking Water Treatment Plant Conventional Treatment KMnO4 Pre-Oxidation ph adjustment with CO2 Coagulant and flocculant dosage Clarifiers ClO 2 oxidation Sand filters GAC Filters Membrane Treatment Electrodialysis reversal (EDR) Remineralisation process (optional) NaClO disinfection 3

5 Llobregat Drinking Water Treatment Plant 4

6 Llobregat River. Llobregat DWTP Raw Water Physicochemical Characteristics High Salinity 1.000~2.100 μs/cm Bromide [ ] 300~900 μg/l Organic Matter 3~10 mg/l Temperature Variations 2~27ºC Low and Irregular Flow Anthropogenic Inputs Mining Activities Upstream Secondary Effluent Source: ICGC 5

7 Trihalomethanes (THM) Formation Distribution Network Cl 2 OM T Br - RT Trihalomethanes CHCl 3 CHBrCl 2 CHBr 2 Cl CHBr 3 Large supply system increase the residence time to generate these disinfection by-products (DBPs) Regulation of RD 140/2003 THM Total Concentration = 100 μg/l!!! 62% 1% 7% 30% Llobregat raw water chemical properties Drinking water usually has a chlorinated profile Llobregat DWTP product water has a brominated profile CHCl3 CHBrCl2 CHBr2Cl CHBr3 6

8 Pilot Test (Looking for a brackish water desalination technology to include in the process to reduce the THMs formation in product water) 7

9 Pilot Tests Design Clarification Sand Filtration GAC Filtration 1 2 GAC Filtration Pilot Plant EDR Pilot Plant Remineralisation 2 8

10 % Removal Pilot Test Results Pilot Test ( ) 26 months m 3 treated hours 91 samplings Br SO 4 NO 3 TACCa K Na Sr Mg EC TOC 9

11 Total THM (ppb) Pilot Test Results 250 Potencial Formación THMs (25ºC) Tc (h) Entrada EDR Salida EDR Especiación THM's Entrada EDR Tc=48 h Especiación THM's Sortida EDR Tc=48 h CHBr3 32% CHCl3 8% CHBrCl2 18% CHBr2Cl 25% CHBr3 4% CHCl3 37% CHBr2Cl 42% CHBrCl2 34% 10

12 Pilot Test Results. Technology Selection Discontinuous production. Frequent operation stops High variability in brackish raw water EDR RO Robust desalination technology YES NO Salt reduction increase with high temperatures YES NO Specific pre-treatment required NO YES High hydraulic recovery YES NO High energy consumption NO YES High membrane renovation costs expected NO YES Remineralisation step can be avoid YES NO 11

13 EDR Technology 12

14 Electrodialysis Reversal (EDR) Technology 13

15 Electrodialysis Reversal (EDR). Cell Pair Cell Pair Anionic Membrane + Spacer + Cationic Membrane + Spacer Complete Stack 14

16 Electrodialysis Reversal. Membranes Anionic Membrane Cationic Membrane 2H 2 O 4H + +O 2 + 4e - 2Cl - Cl 2 +2e - 2H 2 O + 2e - 2OH - + H 2 15

17 EDR Step of Llobregat DWTP 16

18 Llobregat DWTP. Electrodialysis Reversal Step Operation since June 2009 Largest EDR Plant for drinking water treatment application Maximum treatment flow 2.2 m 3 /s Pump station 9+3 pumps of m 3 /h Cartridge filters 18 box filters with 170 cartridge filters 576 stacks distributed in 9 modules 600 cell pairs each stack in double stage 17

19 Llobregat DWTP. Electrodialysis Reversal Step 18

20 Electrodes Metallic Electrodes Carbon Electrodes We operate in parallel with the improvement of the EDR technology 19

21 Membranes and Spacers Spacers AR 204 AR 908SRE AR 908SR AR 908E 20

22 EDR Pilot Plants Treated Flow 10 m 3 /h + 10 m 3 /h 22

23 Preventive and Corrective Maintenance Punctual problems related to scale due to operational problems such as lack of water flow EDR advantage It is possible to stop this stack and replace the units affected 21

24 Operational Improvements. VAMP 22

25 Operational Data 23

26 Treated Volumes (March 2009 May 2017) m Conventional Treatment Blend DWTP Product DWTP Product EDR Product EDR 24

27 Total THMs [μg/l] THMs Formation Potential Reduction 120 Reduction of precursors ,7% ,9% Reduction of THMFP Hores GAC Filtered Water EDR Product GAC+EDR Water (50/50) Total volume treated with EDR determines the mixture and the reduction of THMFP 27

28 Conclusions 28

29 Conclusions 1. EDR is a robust technology compatible with shutdowns of the process related to quality of river raw water 2. High removal for ionic compounds (higher for divalent ions) 3. High removal efficiency of THMs precursors (including organic matter) 4. Improve the organoleptic quality of product water 5. Low energy consumption and high water recovery (>93%) 6. Variability in removal efficiency with temperature of raw water 10% increment with high temperatures 7. Conventional maintenance program and operational hours accumulation (aging) do not cause a decreasing efficiency 29

30 Thank you for your attention