Alternative Regeneration of Combined Ion Exchange Resins with K+ and HCO3

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This research was funded by

Environmental Engineers of the Future

funding program to GM and faculty start-

up funds from THB.

Gabe Maul (M.E., 2013) Dr. Treavor H. Boyer

Overview and Objectives

Water treatment with ion exchange requires the production of concentrated NaCl solution for regeneration that poses

a significant risk to the environment. Increasingly stringent regulations on regenerant disposal can make the entire

ion exchange process cost prohibitive. Alternative regeneration, the use of regeneration solutions that are more

environmentally benign than NaCl, has the potential to significantly improve the sustainability of ion exchange.

Combined ion exchange, the idea of using both cation and anion exchange resins simultaneously, has recently

emerged offering synergistic benefits in both treatment and regeneration. Although several applied studies have

compared NaCl and an alternative regenerant, a fundamental understanding of ion exchange interactions for a wide

range of ion exchange resins and contaminants is still lacking, and very few studies have investigated regeneration

of combined ion exchange. The goal of this research is to provide improved understanding of ion exchange

interactions with alternative regenerants and combined ion exchange. The specific objectives of this research are (1)

compare regeneration effectiveness of NaCl to alternative regenerants KCl, NaHCO3, and KHCO3 using several

pairs of ion exchange resins saturated with different pairs of contaminants, (2) compare treatment effectiveness of

different pairs of contaminants using several resin pairs saturated with NaCl and alternative regenerants KCl,

NaHCO3, and KHCO3, (3) compare economic, environmental, and social advantages and disadvantages of

alternative regenerants.

Preliminary Conclusions

K+ regenerated C-100 resin acts similarly as Na

+ regenerated resin.

For the Ca2+

/NO3- resin pair at a resin dose based on equivalent regeneration capacities, a regenerant

concentration ratio of 100× resin capacity was high enough to completely regenerate NO3- resin but only

able to regenerate Ca2+

resin to 70% of capacity.

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Treavor H. Boyer, Ph.D. ~ Assistant Professor ~ Department of Environmental Engineering Sciences ~ University of Florida

thboyer@ufl.edu ~ 352.846.3351 ~ www.ees.ufl.edu/homepp/boyer ~ www.twitter.com/WaterWeUpTo

Future Ion Exchange Treatment Plant Current IX Residual Disposal Options

Lessen impact on biological HCO3- used in nitrification

Wastewater Discharge

Improved kinetics Improved removal NO3, ClO4, BrO3

Biodegradation

Fertilize with K+ Inland disposal

Land Application

Inland discharge more viable

Reduced impact to envionment

Surface Discharge

Improved Waste Stream

KHCO3 Brine

Regeneration

...with a waste stream that can be managed sustainably

Coagulation pretreatment

Membrane pretreatment

Stand alone: Ca2+/Mg2+, NOM, NO3

-, BrO3-, ClO4

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...is a robust water treatment process...

TDS: 1,000 – 15,000 mg/L

X+

Ion Exchange...

5%

HCO3-

K+ Y-

Benefits Less volume generated from

use of combined ion exchange Less harmful anions/cations

from alternative regeneration Beneficial reuse Internal regenerant reuse Reduced TDSOutcome Regenerant cost ↑ but,

Disposal cost ↓

Environmental impact ↓

Public health ↑

Min.