1. DOES INORGANIC FOULING LIMIT THE USES OF
ECOLOGICALLY FRIENDLY ANION EXCHANGE?
Christopher A. Rokicki, and Treavor H. Boyer1
Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL
1thboyer@ufl.edu ~ (352)846-3351 ~ http://www.ees.ufl.edu/homepp/boyer/
MOTIVATIONS BACKGROUND
Increased water demands & diminishing high quality water
sources lead to the use of previously underutilized technologies • Ion exchange (IEX) may be a treatment • It is unknown how the presence of
solution for certain waters with higher bicarbonate within the resin structure will
levels of natural organic matter (NOM): react with divalent cations:
NOM
HCO3- Cl- Cl- Cl-
Cl-
Cl- Table 1: Carbonate mineral
Cl- NOM Brine disposal is a major concern,
Cl- Cl- HCO3- H+ solubility products. Table adapted
-
NOM
Cl-
much like RO concentrate, it often HCO3
X2+ from Knovel 20081
Cl- NOM
Cl- Cl- impedes the implementation of this
Species pKsp1
NOM IEX Resin NOM IEX Resin
Cl-
Cl-
technology. IEX Resin HCO3 - H+
Cl- Cl-
HCO3- Cl-
Cl-
Cl-
HCO3- HCO3 -
NOM
HCO3 - • However, brine associated with chloride- X2+
MgCO3 3.68
HCO3-
A) Changing water supply and quality D) Increasing water demands impact demands in B and -
HCO3-
Cl-
Cl- form resin limits the potential applications
CaCO3 8.01
Cl- NOM HCO3
B) Advanced treatment processes needed to meet new generates waste to be treated of IEX. Bicarbonate-form would generate
requirements from changes in A and demands from D E) Effluent contains trace contaminants from C
easier to dispose of regenerant and would
C) Waste generated in chloride-form anion exchange (including high TDS) and D that remain post treatment CdCO3 11.3
needs treatment prevent increase of salinity of local waters.
PRELIMINARY DATA RESULTS CONCLUSIONS
100%
M-Cl Calcium • The presence of calcium in solution negatively
90% impacts the performance of ion exchange for both
80% M-HCO3 50% 50%
r0
chloride-form r0
bicarbonate-form bicarbonate-form and chloride-form. The presence
% DOC removal
70%
r1 r1 of magnesium also impacts performance.
60%
40% 40% • Chloride-form ion exchange isn’t impacted as
50% r2 r2
% DOC removal
% DOC removal
40%
greatly by the presence of divalent cations as
30%
30% r3 30% r3 bicarbonate-form.
20% • Bicarbonate-form anion exchange is greatly
10% 20% 20% impacted by the presence of divalent cations. The
0% presence of magnesium has the most profound and
r0 r1 r2
regeneration#
r3
10% 10%
immediate impact.
Figure 1: Preliminary results showing bicarbonate-form resin • Yes, inorganic fouling does impact bicarbonate-form
performance is on par with chloride-form in absence of divalent ion exchange but subsequent work aims to
cations. Synthetic water contained Santa Fe River NOM, 0% 0%
determine exactly how so the process can be
nitrate, sulfate, bicarbonate, and chloride. Figure adapted from 0 50
Rokicki and Boyer 20112. time (min) 100 0 50 time (min) 100 optimized
Figure 3: DOC removal by chloride-form ion exchange resins over Figure 4: DOC removal by bicarbonate-form ion exchange resins over
multiple regeneration cycles in the presence of calcium. multiple regeneration cycles in the presence of calcium. FUTURE WORK
Magnesium • Complete additional regeneration cycles and
perform regeneration cycles on waters containing
50% r0 50% r0 no cations, and waters containing Co2+.
chloride-form bicarbonate-form
r1 r1 • Investigate the biological fouling of bicarbonate-
40% 40% form biological fouling
r2 r2
• Innovative regeneration by CO2(g) sparging and
% DOC removal
% DOC removal
Figure 2: SEM images of chloride- and bicarbonate-form resin r3 r3 optimization
30% 30%
after 14 regenerations showing inorganic fouling of bicarbonate-
form. Figure adapted from Walker and Boyer 20113.
20% 20% ACKNOWLEDGEMENTS
References
1Knovel, 2008. Knovel Critical Tables (2nd Edition). (2008). 10% 10% I would like to thank Dr. Treavor
Knovel. http://www.knovel.com/web/portal/browse/
display ?_EXT_KNOVEL_DISPLAY_bookid=761 Boyer for all his support and
2Rokicki, C.A., Boyer, T.H., 2011. Bicarbonate-form anion 0% 0% guidance. I would also like to
exchange: Affinity, regeneration, and stoichiometry. 0 50 time (min) 100 0 50 time (min) 100 thank the Boyer research team
Water Research 45, 1329 -1337. for all their help and support in
3Walker K.M., Boyer, T.H., 2011. Long-term performance of Figure 5: DOC removal by chloride-form ion exchange resins over Figure 6: DOC removal by bicarbonate-form ion exchange resins over
and out of the laboratory.
bicarbonate-form anion exchange: Removal of dissolved multiple regeneration cycles in the presence of magnesium. multiple regeneration cycles in the presence of magnesium.
organic matter and bromide from the St. Johns River,
FL, USA.. Water Research 45 (9), 2875-2886.