Dow’s Fort Saskatchewan, Alberta, project, called Path2Zero, is already well-known for its ground-breaking commitment to reaching Net Zero Scope 1 and Scope 2 emissions. The facility retrofit and expansion includes a new ethylene cracker with carbon capture technology, power and steam cogeneration and off-site carbon sequestration. Dow expects the project to triple the site’s ethylene and polyethylene capacity and decarbonize approximately 20% of its global ethylene production. The project will add approximately 1.8 million metric tonnes of ethylene capacity in phases through 2030 and will produce approximately 3.2 million metric tonnes of low- to zero-carbon emissions polyethylene and ethylene derivatives. Since 2005, Dow has made commitments to reduce its net annual carbon emissions by about 30% by 2030.

To make all this sustainable design possible, Dow had to consider another important utility in addition to power generation. Clean water is critical to its processes, and chemical manufacturers are facing stricter guidelines on wastewater disposal. Path2Zero has also been designed around water infrastructure—from treating river water for production to recovering its cooling-tower wastewater and converting it back into usable process and boiler-feed water.

“Water management is central to Path2Zero because manufacturing reliability, operational resilience and environmental performance all depend on having a consistent, high-quality water supply and responsible treatment systems,” says Kreshka Young, North America business director of energy and climate at Dow. 

The project’s defining characteristic is its integration of power generation, emissions reduction and water treatment infrastructure, Young adds. “Fort Saskatchewan already operates as a highly integrated manufacturing site, with feedstock, ethylene production, polyethylene production, power, steam, water, storage, rail and logistics all depending on one another. Path2Zero builds on that foundation by expanding and retrofitting the site as one connected system,” she says.

The project was also chosen for its competitive market, where Dow already had strong existing infrastructure. The site is also near carbon transportation and sequestration infrastructure. Young made a point to mention the workforce and community. The area has the needed skilled workers, a supportive pubic and experienced partners.

Water reuse and wastewater constraints shape industrial expansion

As chemical manufacturers expand production across the U.S., water availability and wastewater discharge limits are also constraining where and how new facilities are built. At Fort Saskatchewan, Dow is building on an existing brownfield manufacturing site to add ethylene and polyethylene capacity, as well as retrofitting existing assets and upgrading the utility infrastructure. The site depends on a reliable water supply for cooling industrial processes, and water treatment and reuse will also support production.

“By designing water systems alongside the broader facility, Dow can better align water quality, supply, reuse and wastewater minimization with the needs of both existing and new operations,” Young adds. The integrated approach, she said, supports responsible growth as the site expands. 

In a world where water is becoming scarcer and wastewater is facing increasing regulation, Dow centered on water reuse and wastewater management, alongside energy sustainability. “Water is not just a utility at a site of this scale; it is part of the operating system,” Young says. 

Dow selected Xylem to not only integrate a water-treatment system but also operate and maintain the system long-term. Water reuse was designed into the project because wastewater management is constraining industrial expansion all over. “Most plants in the U.S. treat the wastewater and send it back into a river body,” says Kishor Nayar, director of chemical industry business at Xylem.

However, industrial projects are encountering more limits on the amount of treated wastewater they can discharge into local waterways, he adds. Those limits are based in part on the capacity of the receiving river or other water bodies to absorb additional discharge without negatively affecting the environment, and the limits are not imposed facility by facility. Limits are affected by the cumulative discharge of everyone along the waterbody. 

To allow for expansion, “What that’s forcing a lot of companies to do is increase the wastewater treatment or reduce the wastewater discharge flows,” Nayar says. 

While freshwater availability is another consideration for new projects, Nayar says, the rising discharge limitations are a more immediate driver for reuse. Also, some older facilities have more leeway on wastewater discharges, Nayar says, because they’re operating on older permits. However, new plants and expansions need new permits, and the wastewater regulations affect manufacturers far beyond chemical processing. Investing in sustainability has many benefits, but, Nayer says, for new industrial development, it’s becoming more of a necessity to fuel growth, rather than an add-on investment.

“The 90% recovery or reuse aspect from cooling tower blowdown, that’s pretty unique in North America,” Nayar says.

Industrial water treatment converts river water for process use

Xylem’s role encompasses the entire water treatment system. “We are designing, building, owning and operating an integrated water treatment system,” he says.

The treatment system has two primary functions. First, it will treat river water and convert it into water suitable for cooling and industrial processes. Second, it will recover cooling-tower blowdown wastewater and convert it into demineralized water that can be reused for the boiler feed and other process applications.

That water recovery and reuse is particularly important to chemical manufacturers. Rather than sending the majority of cooling tower blowdown through a conventional wastewater-discharge pathway, the Xylem system is designed to recover most of that wastewater in varying stages of purity for different applications. The remaining wastewater (about 10%) will be managed through Dow’s existing site infrastructure and discharge processes.

The water treatment system begins with water from the North Saskatchewan River. Xylem will use ballasted clarifiers followed by filtration systems to convert the river water into water suitable for cooling and process applications.

The ballasted clarification process, called the CoMag System, uses magnetite to accelerate settling. Because magnetite is substantially denser than water, it allows suspended material to settle more rapidly than in conventional gravity-based clarification.

The magnetite also reduces the footprint required for clarification, while treating larger volumes of water than conventional technology. After clarification, the water moves through a horizontal media filtration before it’s ready for cooling and process uses. “That water goes into the cooling towers at the facility,” Nayar says.

The cooling towers can cycle that water many times, then discharge the wastewater. Instead of treating that stream solely as wastewater, Xylem will feed it into another treatment train designed to recover the wastewater.

“We take that and we do some physical chemical treatment, and using membranes, separate out the sludge, and we create a feed that is good enough to send into reverse osmosis systems,” Nayar says. The reverse-osmosis system then produces water at different purity levels for different applications.

Water treatment reliability depends on monitoring and maintenance

Path2Zero is guided by sustainability principles that support the environment and the most efficient operations. Given the current water infrastructure landscape, being in the water business might not be profitable for many facilities, including Dow.

“We’re not in the water treatment equipment business. We are in the water treatment performance guarantee business,” Nayar says. Like many products, Xylem offers water as-a-service and contracts that guarantee water quality and quantity. Xylem is managing the build and will also operate and maintain operations on-site. 

The water treatment business is additionally complicated because water treatment and water guarantees require dealing with changing influent conditions, depending on the weather. “The feed is seasonal,” Nayar says. 

Membrane performance also depends on proper installation and maintenance, which can be difficult and requires experienced service technicians. “The layer of a membrane that actually removes the salt ions or salty particles and makes pure water, it’s thinner than the diameter of a human hair,” Nayar says. The membrane itself requires pretreatment protections before installation. “I would say we make it look easy, but it’s not easy,” he adds. 

Customers can easily clog up the systems without the right staff and expertise, and water treatment is often not the core expertise of Xylem’s customers.

“Normally, customers get a better return from using their capital and investing in their core assets that generate a return for them,” Nayar says. Water treatment investment typically does not return profits for manufacturers, he adds.

The continuous operation and reliability of the water system is an “operational philosophy” for the company, Nayar says, and the result of decades of experience. Xylem’s Link2Site web monitoring and control system provides remote monitoring capabilities, including sensors that can indicate changes in pressure and membrane performance. Scheduled cleaning and equipment-replacement programs are all incorporated into the operating plan.

For membrane systems, those maintenance practices include routine backwashing, chemically enhanced backwashing and clean-in-place procedures. Depending on the type of membrane and the cause of fouling, cleaning can involve different chemical treatments.

“We know where the fouling potential is highest, and we’ve already budgeted in how many years of replacement, how many years of life we need to budget for in different stages of the process,” Nayar says.

The system also incorporates redundancy. “A lot of it comes down to conventional maintenance basics,” Nayar says. “The operational reliability, the schedules, having N+1 equipment, having spare parts.” The combination of scheduled maintenance and condition monitoring allows Xylem to anticipate maintenance needs and also respond to changing operating conditions with the seasons.

Nayar emphasized that while automation is prevalent on the processing side of chemical manufacturing, that does not eliminate the need for people, especially on the water treatment side, “Because the nature of the membrane technology does require a fair bit of oversight,” Nayar says.

Path2Zero offers a model for sustainable industrial facility design

For Dow, integrating water infrastructure into the Path2Zero project from the beginning is part of a broader approach to facility design, integrating profitability and sustainability in tandem. “The goal is not to treat sustainability as a separate program, but to build it into how the site is designed, operated and maintained over time,” Young says.

Nayar sees the same trend from the water treatment side. He expects chemical manufacturers in North America to make more proactive investments in water reuse and wastewater infrastructure as industrial development encounters tighter discharge constraints and increasing water scarcity.

The challenge, he says, is that companies cannot necessarily build water-treatment infrastructure quickly once a problem emerges. “A permanent system takes a few years in some cases, if it’s a massive facility,” Nayar says. 

That makes planning critical. Companies that wait until drought, water scarcity or wastewater-discharge constraints may have limited options. Skilled workers to maintain complex water treatment systems could be an issue moving forward too.

“The industry broadly has to think ahead and be proactive and make those investments, knowing where the direction is going,” Nayar says.

Dow is already planning for the future and the infrastructure required for lower-emissions manufacturing, from carbon capture and energy systems to freshwater processing and wastewater reuse.