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Introducing XBAT.

As one utility director recently stated, “All of the good water is gone.”

Water quality deterioration along with growing demand and the challenges posed by climate change have resulted in the need for sustainable water supplies across North American communities. Traditional water treatment methods struggle to meet these demands efficiently, especially when confronted with the challenges of salinity, organics, and emerging contaminants.

Enter Ion eXchange-Based Advanced Treatment (XBAT), a multi-benefit alternative technology developed by Carollo Engineers that is set to transform the landscape of water, wastewater, and recycled water purification. By integrating suspended ion exchange (SIX) with lime softening process, XBAT achieves unmatched performance in reducing salinity and total organic carbon (TOC) without relying on reverse osmosis (RO) and its associated residual disposal challenges.

In most applications, XBAT will be a complement to existing water and wastewater treatment processes to provide either pretreatment or polishing to improve overall treated water quality.

0.8%
Generates waste brine stream of only 0.8% of total feed water flow, maximizing resource utilization and minimizing environmental impact.
35+%
Achieves high TOC removal rates (greater than 35% on average) without generating large volumes of solid and/or liquid treatment residuals.
50%
Achieves significant salinity reduction (50% on average) to prevent the up-cycling of inert anions in the water cycle and without the reliance on energy-intensive high pressure membrane processes.
70+%
Demonstrates remarkable removal rates across various anionic contaminants, including chloride, sulfate, nitrate, bromide, and phosphate.
pipe discharging water

Challenges of Existing Technologies

Salinity poses a significant challenge to reuse as wastewater effluents often contain elevated salinity levels compared to traditional water sources.

The status quo salinity treatment approach relies on the use of reverse osmosis (RO) or nanofiltration (NF). This approach presents brine waste stream management challenges, especially for inland communities where ocean discharge is inaccessible or deep well injection is restricted, and for communities where 8-15% water loss as a brine waste stream is deemed unacceptable.

Prevailing alternative advanced treatment methods, such as carbon-based advanced treatment (CBAT), do not produce a brine waste stream, but cannot address salinity through any of the unit treatment processes. Thus, both RO-based advanced treatment (RBAT) and CBAT approaches have significant limitations in salinity treatment.

illustration of process components

XBAT

XBAT leverages cutting-edge technology to simultaneously target salinity and other challenging water quality parameters.

One such parameter, TOC, is a crucial constituent that must be controlled to prevent the formation of disinfection byproducts, the fouling of membranes and adsorptive media (e.g., granular activated carbon), or prevent re-growth problems in distribution systems and receiving waters.

XBAT also has the capacity to remove anions, such as chloride, nitrate, phosphate, bromide, and emerging contaminants, including PFAS, thus solving a wide range of pervasive and previously intractable water quality challenges.

Discover XBAT

In this explainer video, Carollo’s National Water Reuse Technical Practice Director Eva Steinle-Darling explains how XBAT addresses the unique challenges of salinity, organics, and emerging contaminants in water, wastewater, and reuse applications.

illustration of the XBAT treatment process

How it Works

XBAT redefines water treatment through a synergistic process, meticulously designed to address both salinity and TOC with unparalleled efficiency.

Suspended Ion Exchange (SIX):

At the heart of XBAT lies the SIX process, a novel ion exchange process developed by Nijhuis Saur Industries (previously PWN Technologies), where water is treated with ion exchange resin in suspension. This type of resin is specially engineered to adsorb negatively charged ions (anions) such as TOC, chloride, bromide, nitrate, nitrite, sulfate, phosphate, and sometimes PFAS. SIX is a steady state process, allowing for continuous treatment as resin flows through the contactor and is subsequently separated from the water by plate settlers and collected in a hopper below.

Resin Regeneration with Bicarbonate:

Regeneration of the resin is achieved using a bicarbonate regenerant, which effectively displaces the captured ions contaminant anions from the resin, refreshing it for the next treatment cycle. The innovative use of bicarbonate for resin regeneration in the SIX process represents a significant advancement, reducing the environmental impact by producing a waste brine stream that is small in volume and with a reactive chemistry to allow for further treatment (e.g., softening) and volume reduction.

A bicarbonate regeneration waste stream differs from a traditional chloride-based waste stream. Bicarbonate can offer benefits at wastewater facilities. In particular, high concentrations of bicarbonate can lead to precipitation reactions that significantly remove accumulated contaminants in the waste stream, such as bicarbonate, phosphate, organics, fluoride, and sulfate.

Lime Softening:

Following SIX, the water undergoes lime softening, a time-tested water treatment process. Lime (calcium hydroxide) is added to the SIX effluent, reacting with calcium and magnesium to form calcium carbonate, and potentially magnesium hydroxide precipitates. This step not only aids in hardness removal but also helps in consuming access bicarbonate in the SIX effluent to achieve further salinity reduction.

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