There’s little question that the world is facing a serious water crisis, and industry is right in the middle of it, competing with agriculture and municipalities for a share of the globe’s scarce water resources. The United Nations’ Food and Agriculture Organization (FAO) says industry uses 18.7 percent of available water worldwide and 43 percent in North America. To confront water risks, some companies are pursuing a strategy known as “green infrastructure” or “GI.”
According to the U.S. Environmental Protection Agency (EPA), green infrastructure is a planned, strategic approach that manages water in a natural way. Normally when we talk about infrastructure, we think about elements like buildings, roads, bridges, energy sources, power transmission, and communications lines — “gray infrastructure.” But, according to The Conservation Fund, the concept of “infrastructure” can be expanded: “Just as we plan networks of roads, we can plan networks of open spaces and natural resources that connect communities and regions,” says the organization, which works to form collaborations around development of green infrastructure. Green infrastructure can be practiced at various scales, including that of a site, city, or region.
Dow Chemical in Seadrift
In a recent interview, Neil C. Hawkins, vice president for sustainability and global environmental health and safety at Dow Chemical Co., told me that “the availability of water both for today but also into the future is a strategic issue for Dow.” As a result, he said, “we pay a lot of attention to water supply and water risk in terms of quality and quantity.”
One longstanding GI project was undertaken in the late 1990s at the North Seadrift, Texas site of Dow’s subsidiary Union Carbide, where the company developed a constructed wetland for treatment of wastewater. The Seadrift complex is used to produce plastic resins and other chemicals. Wastewater from multiple facilities, along with stormwater, was originally routed through a traditional treatment system using primary and secondary treatment ponds and a shallow 267-acre tertiary pond. However, the existing system was not meeting EPA effluent standards, and a new solution had to be found.
Carbide elected to replace the tertiary pond with a 110-acre constructed wetland that met EPA requirements for total suspended solids (TSS) and eliminated algae blooms and naturally controlled the pH of the discharge. The GI project required an investment of only $1.2 to $1.4 million, as opposed to an estimated $40 million for a gray-infrastructure alternative. A case study, developed by Dow and other companies in partnership with The Nature Conservancy and included in a larger report, says that operational support for the engineered wetland is “drastically different” from that of a conventional solution, “as a wetland requires minimal support from operations and maintenance, while the gray alternative requires 24/7 support.” The project was completed in only 18 months, was 100-percent compliant from day one, and has operated successfully now for 15 years.
Interestingly, the case study says that the wetland has taken on a life of its own and has turned out to be “self-organizing”: “the wetland does not look like what was built” and is now “a diversified biota from plants to micro-organisms, increasing the built-in stability of the mini-ecosystem to respond to fluctuations.” The case study blandly observes that the wetland has created wildlife habitat such that “the main disturbances that the system has to manage” are “biotic stresses” such as alligators and bobcats.
Alcoa in Saudi Arabia
The aluminum company Alcoa recently completed an engineered wetland project in Saudi Arabia at the site of its joint venture with The Saudi Arabian Mining Company (Ma’aden), where the company operates a refinery, smelter, and rolling mill. The system, designed by Alcoa and called Natural Engineered Wastewater Treatment, treats industrial and sanitary water in three steps. First, an anaerobic treatment tank breaks down organic material in the water and separates it. The second stage is “a passive engineered wetland that utilizes vegetation for further treatment of organics and removal of nitrogen and metals.” Then the water is disinfected and polished using a bauxite-based technology in a cell housing.
Ray J. Kilmer, executive vice president and chief technology officer (CTO) at Alcoa, told me in an interview that bauxite is a by-product of the aluminum extraction process, so the engineered wetland technology helps Alcoa make use of a potential waste product. “We found that the bauxite residue could actually help disinfect waste.” In fact, he said, “it gets rid of the bad bacteria but not the good bacteria. The water comes out cleaner than in a traditional tank-based system.”
The Alcoa wetlands-based system will reduce demand for water at the Ma’aden aluminum facility by nearly 2 million gallons and is expected to save $7 million a year in freshwater purchases. The water will be reused at the facility for manufacturing and irrigation. Alcoa says the wetlands system “cleans and disinfects the water without the use of chemicals or the creation of water discharge and odors associated with conventional tank systems.” Building the system took six months less than a conventional tank system and saved 1,000 metric tons of steel normally consumed in piping and tanks.
Kilmer told me that he thinks the Natural Engineered Wastewater Treatment works “because we’re mimicking the earth’s processes, and the earth can heal itself. If we can just use the mechanisms that mother nature has already put in place — and maybe help that with some engineering — it creates a tremendous opportunity to clean and restore the world we live in.” Kilmer said Alcoa plans to extend the technology to other sites and to commercialize it as well.
Shell in Nimr, Oman
The Nature Conservancy report also profiles a project by Shell Petroleum Co. demonstrating how natural systems can be used to protect water resources. Shell operates Petroleum Development Oman LLC (PDO) as a joint venture with the Government of Oman at the oil fields in Nimr, Oman.
Originally, the Nimr site was bringing up a large volume of water along with the crude oil — a full 330,000 cubic meters per day. That water was simply being disposed of by injection into a well. PDO contracted with engineering firm Bauer Resources to develop a 360-hectare four-tier gravity-based wetland system using reed beds to filter the water. The report says that “The oil is eaten by microbes that naturally feed on hydrocarbons underground.”
The wetland system is able to treat 95,000 cubic meters of water a day. The design “requires close to zero energy for water treatment, thus reducing power consumption by approximately 98 percent … due to the elimination of electric-powered water treatment and injection equipment” and “enables an additional crude oil recovery of 200 barrels per day.” The wetlands also provide habitat for fish and birds.
In its discussion of the Dow and Shell case studies, along with others, The Nature Conservancy emphasizes that green infrastructure doesn’t work for every situation — decision makers need to consider the site and overall project risks. However, GI should definitely “form an essential element in a portfolio of solutions to increase the resilience of industrial business operations.” GI solutions use less energy, offer unique resiliency, and often demonstrate “financial advantages compared to gray infrastructure due to a reduction of initial capital expenses and ongoing operational expenses.”