Understanding the value of water reuse in the face of water scarcity
Dozens of manufacturing industries rely on a steady flow of clean fresh water to keep their production lines humming. There simply is no alternative or replacement. Unfortunately, plant managers find themselves squeezed by high water costs and declining availability on the front end, and by increasingly complex discharge requirements on the back end. The familiar issue of water quality and variability also is becoming a bigger challenge for plant operators.
Difficult as the industrial water challenge is now, it soon could become much worse. In just 13 years, the United Nations estimates the world will only have access to 60% of the freshwater resources it needs if no action is taken. At the same time, global manufacturing demand for water is anticipated to increase by 400% from 2000 to 2050.
Needless to say, the cost of water directly impacts the cost of business. This is why water-intense industries—such as power generation, chemical, municipal, and oil and gas—are making renewed efforts to reduce their water consumption. They also are starting to take advantage of a vast resource that historically has been overlooked: wastewater.
The Largest Water Conservation Opportunity
Wastewater is increasingly recognized as an invaluable, yet largely untapped resource. Globally, more than 80% of municipal, industrial and agricultural wastewater still flows back to nature without being treated or reused. This not only pollutes rivers and oceans, but also represents gross mismanagement of a precious resource.
More and more industries—often in partnership with local municipalities—are using recycled wastewater as a cost-effective means of ensuring a reliable supply of water that meets industrial quality specifications. This “circular economy” approach to water conservation is made possible by a host of existing water treatment technologies.
Various combinations of wastewater treatment technologies typically are needed based on source water quality and local and national regulations. In California—well known for chronic water stress and drought conditions—Dow reverse osmosis (RO) elements are helping the Orange County Water District treat reclaimed municipal wastewater from 850,000 residents for reuse in a variety of local industries, including carpet dying and power generation. Apart from increasing water availability, this initiative has helped the district lower its water treatment facility energy use by 13%, reduce operating costs and lower its carbon footprint.
In Texas, a public-private partnership with the city of Lake Jackson diverted the city’s treated wastewater effluent to Dow’s raw freshwater canal for operational use in its Freeport, Texas, operations facility. By reusing the city’s wastewater for industrial operations, Dow has reduced freshwater use by more than 1.3 billion gal per year. These freshwater savings could supply a community of approximately 30,000 people for one year.
Tailoring Wastewater Systems
As these examples demonstrate, every industrial site and location face different water challenges. Implementing a “one size fits all” water treatment system is not effective or cost efficient. Water utilities and manufacturing companies must analyze their specific needs and implement optimal designs and technologies to create cost-effective wastewater treatment systems.
Wastewater treatment requires more than one technology, and it also requires applications knowledge to design and apply the technologies based on wastewater content and specified or regulated purity. Individual water treatment technology design tools are useful, but can make it difficult to optimize systems that require multiple technologies.
The Water Application Value Engine (WAVE) design software helps solve this problem by integrating three widely used water treatment technologies—ultrafiltration, RO and ion exchange—into a comprehensive tool with a common interface. The engine simplifies the multi-technology design process to reduce the time it takes to design and estimate performance of customized water treatment systems using these three technologies.
Accurate performance and economic evaluation of each technology and its system-wide integration is key to making informed decisions. Operators using the software can set, reset and calculate plant designs quickly, and make changes to unit operations that automatically propagate throughout the design.
It also includes default values and site-specific parameters to increase the accuracy of OPEX calculations, as well as report on multi-technology plant performance and cost. Advances in software design can help fine-tune technology at the point of use to produce the right water quality for specific needs. It comes down to using the right technologies at the right time so that the system design is efficient and cost-effective.
The Circular Economy Imperative
The idea of continually recycling and reusing raw materials no longer is a pipe dream for industrial water users; it rapidly is becoming a survival imperative. Water availability and variability impacts the bottom line of every manufacturing company and virtually every human endeavor. Indeed, without clean, potable water, we all would perish.
Water conservation through the reuse of wastewater is a critical step for both public and private organizations. But technology alone cannot meet every water challenge. We also need new approaches and innovative thinking.
Minimal liquid discharge (MLD) also helps industrial and municipal operators address water footprints and move toward a circular economy without breaking budgets. Reaching the final 3 to 5% of liquid elimination to achieve zero liquid discharge (ZLD) is an admirable goal, but it has proven to be prohibitively expensive in terms of capital and operating costs.
Aiming for a 95% water recovery rate using the MLD approach can achieve results for a fraction of the cost of ZLD. The MLD process relies on a core set of proven, existing water technologies, but the real key is evaluation of situational needs to identify sources and types of wastewater, followed by combining appropriate technology systems for optimal and economical results.
Advanced technology and the application know-how already exist to transform wastewater into the largest cost-effective, sustainable water conservation resource available. And with it, other innovative approaches will be critical to consider as the industry continues to evolve toward the circular economy ideal.