Ion exchange for NOM removal

Transcription

1 Ion exchange for NOM removal from a sulfaterich surface water incorporating full reuse of the brine Feasibility study at WTW the Blankaart L. Verdickt, V. D Haeseleer, W. Closset, J. Cromphout VMW (Flemish Drinking Water Company) Vooruitgangstraat 189, 13 Brussels (Belgium) liesbeth.verdickt@vmw.be

2 Layout Introduction > WTW the Blankaart > Why ion exchange? > Specific points of attention Materials and methods Results Conclusions

3 WTW the Blankaart > Diksmuide, Belgium > 4. m³/day > River IJzerand surrounding lowlands stored in reservoir (3 Mm³) DOC 11.1 mg C/L UV 254 adsorption 24.6 m -1 Sulfate 1 mg/l Chloride 96 mg/l Nitrate 17 mg/l Alkalinity 3.9 meq/l ph

4 WTW the Blankaart > Diksmuide, Belgium > 4. m³/day > Water from river IJzer and surrounding lowlands > Current treatment Trickling filters (ammonia oxidation) Enhanced coagulation (FeCl 3 + H 2 SO 4 ) Decantation Rapid sand filtration GAC filtration Disinfection (NaOCl)

5 WTW the Blankaart > Diksmuide, Belgium > 4. m³/day > Water from river IJzer and surrounding lowlands > Current treatment > Disadvantages High chemicals demand (high alkalinity) 2 mg Fe/L 8 mg H 2 SO 4 /L High waste production DOC in finished water still 3.3 mg C/L

6 WTW the Blankaart > Diksmuide, Belgium > 4. m³/day > Water from river IJzer and surrounding lowlands > Current treatment > Disadvantages Search for new strategies for improved NOM removal

7 Why ion exchange? > Applicable to raw water (fluidized bed system) > High NOM removal, low chemicals demand Resin dose (ml/l) Lab scale Pilot Full scale Lab-scale results from Singer and Bilyk (22), Drikas et al. (23), Fearing et al. (24), Johnson and Singer (24), Morran et al. (24), Boyer and Singer (25), Humbert et al. (25), Humbert et al. (27), Kitis et al. (27), Mergen et al. (28), Sani et al. (28), Apell et al. (21). Pilot scale results from Hammann et al. (24), Wert et al. (25), Boyer and Singer (26), Shorrock and Drage (26), Singer et al. (27), Cromphout et al. (28), Jarvis et al. (28). Full-scale results from Morran et al. (24), Warton et al. (27), Hsu and Singer (29). DOC removal efficiency (%)

8 Ion exchange at the Blankaart > High sulfate concentration (1 mg/l on average) > Complete brine reuse Flocculation with Fe-salt Filter press Addition of NaCland NaOH Impact of sulfate accumulation in the brine? > Fluidized bed systems Miex Conventional resins

9 Layout Introduction Materials and methods > Pilot trial > Column experiments Results Conclusions

10 Pilot trial > Capacity 1 m³/h > June 28 July 29 > Regeneration with NaCl 1% > Miex resin, ERD 1 ml/l > Measurement of DOC UV 254 Cl -, SO 2-4, NO3 -, alkalinity Na + ph, conductivity, turbidity

11 Column experiments > Capacity 15 L/h > > In situ regeneration NaCl, Na 2 SO 4 Brine reuse > Miex resin, conventional resins > Analyses DOC, UV 254, Cl -, SO 2-4, NO3 -, alkalinity, Na +, ph, cond., turb. After 6, 1, 2, 3, 6, 9, 12, 15 bed volumes

12 Layout Introduction Materials and methods Results > NOM removal > Removal of competing anions > Regeneration with sulfate versus chloride > Brine recuperation > Miex and conventional resins in fluidized bed Conclusions

13 Percentage removal NOM removal > UV 254 adsorption: 6 to 7% removal UV254 (1/m) Jul-9 Jun-9 May-9 Apr-9 Mar-9 Jan-9 Dec-8 Nov-8 Oct-8 Sep-8 Aug-8 Jul-8 Jul-8 UV254 raw UV254 treated Percentage removal

14 Percentage removal NOM removal > UV 254 adsorption: 6 to 7% removal > DOC: 4 to 5% removal DOC (mg C/L).. Jul-9 Jun-9 May-9 Apr-9 Mar-9 Jan-9 Dec-8 Nov-8 Oct-8 Sep-8 Aug-8 Jul-8 Jul-8 DOC raw DOC treated Percentage removal

15 NOM removal > UV 254 adsorption: 6 to 7% removal > DOC: 4 to 5% removal DOC removal efficiency (%) Resin dose (ml/l) Lab scale Pilot Full scale

16 Removalof competinganions Average raw water Average effluent (%) (meq/l) Cl mg/l 96.5 mg/l +17% +.4 SO mg/l 91.5 mg/l -9% -.19 NO mg/l 17.7 mg/l -3% -.1 Alkalinity 3.67 meq/l 3.62 meq/l -1% -.5 Na mg/l 56.2 mg/l +4% +.12 DOC 1.5 mg C/L 6.1 mg C/L -42% -.3 UV 254 ads m m -1-68%

17 Pilotresults > Effective resin dose: 1 ml/l, regeneration with NaCl > NOM removal UV 254 : 6 to 7% removal DOC: 4 to 5% removal Lowest efficiency during summer > Chloride exchanged:.28 meq/l 68% attributable to sulfate removal 11% attributable to DOC removal

18 Regeneration with Cl - > Miex regenerated with Cl - (1.84 eq/l resin) Inorganic anions (meq/l) UV254 DOC SO4 Cl NO3 Alkalinity UV254 (1/m), DOC (mg C/L) Raw 6 bv 1 bv 2 bv 3 bv 6 bv 9 bv 12 bv 15 bv

19 RegenerationwithCl - > Miex regeneratedwithcl - (1.84 eq/l resin) Inorganic anions (meq/l) BV 1 BV UV254 (1/m), DOC (mg C/L) 15 BV UV254 DOC SO4 Cl NO3 Alkalinity Raw 6 bv 1 bv 2 bv 3 bv 6 bv 9 bv 12 bv 15 bv

20 RegenerationwithCl - > Miex regeneratedwithcl - (1.84 eq/l resin) Inorganic anions (meq/l) BV 1 BV ERD = 1 # bed volumes UV254 (1/m), DOC (mg C/L) UV254 DOC SO4 Cl NO3 Alkalinity Raw 6 bv 1 bv 2 bv 3 bv 6 bv 9 bv 12 bv 15 bv 15 BV

21 RegenerationwithCl - > Miex regeneratedwithcl - (1.84 eq/l resin) Inorganic anions (meq/l) 1 5 ERD 2.5 ml/l ERD 1 ml/l ERD = 1 # bed volumes 4 3 UV254 (1/m), DOC (mg C/L) ERD.7 ml/l UV254 DOC SO4 Cl NO3 Alkalinity Raw 6 bv 1 bv 2 bv 3 bv 6 bv 9 bv 12 bv 15 bv 2 1

22 RegenerationwithCl - > Miex regeneratedwithcl - (1.84 eq/l resin) Fraction removed UV254 DOC SO4 Cl NO3 Alkalinity 4 bed volumes 1 bed volumes 15 bed volumes

23 RegenerationwithCl - > Miex regeneratedwithcl - (1.84 eq/l resin) UV254 DOC SO4 Cl NO3 Alkalinity Fraction removed Pilot Column

24 Regeneration with SO 4 2- > Miex regenerated with SO 4 2-(1.84 eq/l resin) 25 5 Inorganic anions (meq/l) UV254 (1/m), DOC (mg C/L) UV254 DOC SO4 Cl NO3 Alkalinity Raw 6 bv 1 bv 2 bv 3 bv 6 bv 9 bv 12 bv 15 bv

25 RegenerationwithSO 4 2- > Miex regeneratedwithso 4 2-(1.84 eq/l resin) Fraction removed UV254 DOC SO4 Cl NO3 Alkalinity 4 bed volumes 1 bed volumes 15 bed volumes

26 Regeneration with Cl - /SO 4 2- > Miex regenerated with Cl - Column experiments representative for large scale Sulfate removal highly reduced by operating at low ERD > Expectations for complete brine reuse Negligible impact on NOM removal Lower removal of inorganic anions UV254 DOC SO4 Cl NO3 Alkalinity bed volumes 1 bed volumes 15 bed volumes Fraction removed UV254 DOC SO4 Cl NO3 Alkalinity 4 bed volumes 1 bed volumes 15 bed volumes Fraction removed

27 Brine reuse > Series of 14 experiments with complete brine reuse Fraction removed UV254 DOC SO4 Cl NO3 Alkalinity 4 bed NOM conference volumes July bed volumes 15 bed volumes UV254 DOC SO4 Cl NO3 Alkalinity 4 bed volumes 1 bed volumes 15 bed volumes Fraction removed

28 Brine reuse > Negligible impact on NOM removal > Lower removal of inorganic anions > Salt consumption reduced by factor 4 Addition of 26 g NaCl/L brine 6 g FeCl 3 /L brine (flocculation).3 g NaOH/L brine (ph correction) 1% NaCl contains 17 g NaCl/L

29 Miex or conventional resins > Column experiments with Miex, Purolite A86S, Lewatit VPOC 171 > Similar removal efficiencies > Conventional resins require higher contact time Fraction removed UV 254 adsorption DOC.1 37 s 6 s 12 s 37 s 6 s 12 s 4 bv 1 bv 15 bv 4 bv 1 bv 15 bv (Purolite A86S with brine reuse) Fraction removed

30 Layout Introduction Materials and methods Results Conclusions

31 Pilot plant findings (ERD 1 ml/l, regeneration with NaCl 1%) > NOM removal UV 254 : 6 to 7% removal DOC: 4 to 5% removal Lowest efficiency during summer >.28 meq/l of chloride exchanged 68% attributable to sulfate removal 11% attributable to DOC removal

32 Brine reuse > No significant impact on NOM removal > Reduction of unwanted removal of inorganics > Reduction of salt consumption by factor 4 Miex versus conventionalresins > Similar removal efficiencies > Conventional resins require higher contact time