Produced Water
Softening Using
SAC & WAC
Shallow Shell™
Resin Technology
This Application Guide illustrates
how Purolite™ Resins SSTTM Technology
enables unsurpassed regeneration
efficiency and reduced rinse water
requirements for produced water
softening applications.
2
Produced Water Softening Using SAC &
WAC Shallow Shell Resin Technology
Contents
Introduction 3
Advantages of Shallow Shell Technology 4
Cut Operational Costs, Not Performance 5
Produced Water Softening Using SAC & WAC Shallow Shell™ Resin Technology A P P L I C AT I O N G U I D E
3
Introduction
Strong acid cation (SAC) and weak acid cation (WAC) ion exchange resins are typically used in lead-lag tanks
to soften high TDS-produced and brackish water systems. SAC resin in the primary (lead) tank removes the
majority of Ca, Mg and Fe, while WAC resin in the polisher (lag) tank effectively polishes the water to < 0.5 ppm
(as CaCO3) total hardness.
Softening water prevents scale buildup in the boiler tubes which enables the steam generator to provide continus
high quality steam.
Chemicals and water used for regeneration and rinsing of the resins are a significant part of the operating costs
for produced water treatment systems.
The advanced bead structure of Shallow Shell Technology (SST) resin facilitates a higher operating capacity,
efficient regeneration, lower leakage and no fouling. The key to the resin’s efficiency is the resin’s unique shell
and core structure. In the production process, the center of each SST bead is left inactive, eliminating the
functional sites, are the most difficult to regenerate and are the most susceptible to fouling.
As regenerant passes through beads and gets consumed, the reaction force diminishes resulting in:
• The bead center remains un-regenerated
• Residual cationic species accumulate within the resin bead (Ca, Fe and other metals)
• The bead becomes fouled
• Higher hardness leakage occurs in the next cycle
• Excessive, expensive amounts of chemicals are required to achieve acceptable regeneration levels
Resin fouling, in large part, is caused by incomplete regeneration, resulting in accumulation of contaminant
species that are the source of higher leakage in subsequent service cycles.
Produced Water Softening Using SAC & WAC Shallow Shell™ Resin Technology A P P L I C AT I O N G U I D E
4
FIGURE 1
Fouling of Ion
Exchange Resin
A graphic depiction of an
un-regenerated core with photo
insert of a standard resin with
a fouled center.
With Shallow Shell Technology, regeneration occurs more quickly and efficiently because chemicals don’t
have to penetrate the entire bead.
• A short, consistent exchange path improves the efficiency of ion exchange
• Higher purity water is produced
Advantages of Shallow Shell Technology
• Requires 15–30% less chemical usage to achieve equal or better operating performance; reduces
operating expenses
• Significantly reduces rinse water
- 30% savings for counterflow operation
- 50% savings for co-flow operation
• Reduces fouling and leakage from Ca, Fe and other metals
• Suitable for co-flow, counterflow and packed bed systems
• Supports ISO 14001:2015 initiatives toward environmental management and impact
- Uses less regenerant chemical and water, resulting in an overall reduction of waste.
Produced Water Softening Using SAC & WAC Shallow Shell™ Resin Technology A P P L I C AT I O N G U I D E
5
Watch the video to learn how Shallow Shell Technology works at https://bit.ly/3D0BJkG.
The positive impact of Shallow Shell Technology on regeneration and rinse efficiency is most apparent when
regenerating WAC resins in HTDS-produced water treatment. Acid, usually HCl, is used to elute the hardness,
while caustic, NaOH, converts the resin sites to the sodium form. With standard WAC, two problems are
experienced — extended time for complete elution of hardness and extended time and volume of water
used for rinsing the resin. As the standard WAC resin ages, carboxylic functional groups hydrolyze and retain
caustic within the resin bead, resulting in a longer rinse-down time of the resin bed. Figure 2 displays the
advantages of SST resin. Figure 2 also indicates that no hardness exists for SST resin during the caustic
(NaOH) injection step, while approximately 2,500 ppm of hardness continues to elute for standard resin.
This residual hardness can result in caustic combining with Ca and Mg to form precipitates of calcium and
magnesium hydroxides within the resin bed. Such solids can result in extremely long fast rinse times to
prevent excessive hardness leakage into the treated water. These are problems that SST resins prevent.
Cut Operational Costs, Not Performance
With Shallow Shell Technology, it is possible to cut operational costs without sacrificing performance.
This product overview illustrates how SST Technology enables unsurpassed regeneration efficiency and
reduced rinse water requirements for produced water softening applications. Contact your regional technical
sales expert to learn how SST resins can make your softening treatment system more effective, efficient and
environmentally sound.
Produced Water Softening Using SAC & WAC Shallow Shell™ Resin Technology A P P L I C AT I O N G U I D E
6
FIGURE 2
WAC Regeneration: SST vs. Standard Resin
ppm Hardness Conductivity
60,00 35,000
HCL Injection HCL Displace NaOH Injection NaOH Displace
50,000 30,000
ppm as CaCO3
25,000
40,000
µmhos/cm
20,000
30,000
15,000
20,000 10,000 µS/cm is
the target fast rinse 10,000
conducitivity
10,000 5,000
0 0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170
Time
Hardness Strip SSTC104 Conductivity C104Plus
Hardness Strip C104Plus Conductivity SSTC104
A comparison between co-current regenerated WAC resin units using Shallow Shell SSTC104 and C104 Plus.
Left Side: Hardness Elution
30% savings in acid is experienced using Shallow Shell Technology resin. Notice how the black line (Shallow
Shell™ SSTC104) peaks and drops off quickly, while the standard resin (green line) drags out into the caustic
injection step. This indicates that the SST resin works more efficiently, while the standard resin takes longer to
achieve the same level.
Right Side: Rinse Conductivity
With a target goal of 10,000 µS/cm, the purple line (Shallow Shell™ SSTC104) meets the target during the
caustic displace step, while the orange reaches the target during the fast rinse. This indicates a significant
increase in regeneration efficiency, leading to a 50% savings in rinse water.
Produced Water Softening Using SAC & WAC Shallow Shell™ Resin Technology A P P L I C AT I O N G U I D E
Customized Resin
Simulation at Your
Fingertips
PRSM is a free program that models all aspects
of plant design associated with ion exchange
resin performance and operation.
Plan your next ion exchange resin project
with better accuracy and less effort through
Purolite’s Resin System Modeling platform PRSM includes modules for water
(PRSM™). This powerful web application for softening, demineralization, WAC
softening, brine purification, mixed beds
resin plant simulation contains seven
and modules for removal of nitrate,
specific system modules that instantly arsenic and boron. Features include:
consider hundreds of variables. Whether Technical Help – Reach out directly to
you are designing a new plant or modeling Purolite engineers for advice
an existing plant, Purolite’s expert engineers Cloud Backup – Easy and secure retrieval
of projects
are giving you the access you need to get
the results you can trust. Reporting – Print/save a pdf of the entire
design including all engineering details
ROI Payback Calculations – Contrast
Key Insight Every Step of the Way performance vs. standard resins
Efficiency Evaluation – Compare
operating costs of existing ion exchange
plant vs. new design
Schedules – Obtain detailed regenerant
Predict Compare Optimize schedules for cation and anion resins
Calculate the Side-by-side Add operation Page, Topic and Calculation Help –
effect of your site’s product and plant and product cost View detailed notes and suggestions
unique variables configuration analysis to better for the optimal design
performance understand the
evaluation value of product
options
Register today and get started at www.puroliteresins.com/PRSM
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Resins including ion exchange, catalyst
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