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Dow wastewater reuse

Dow’s Wastewater Recycling Partnership Closes the Resources Loop

Dow wastewater reuseWater, says Dow’s Niels Groot, “sits at the intersection of necessity and scarcity. Since we do not have a replacement for water, we’ve got to focus on the scarcity side of the picture.”

In an effort to reduce freshwater use at its largest chemical facility, Dow partnered with Evides Water Co. and the city of Terneuzen, Netherlands, where the plant is located to turn waste — in this case, wastewater — into a new product — freshwater for industrial use. The plant accepts wastewater each day from the city, has it purified by the water company, and reuses it for its manufacturing processes.

This wastewater recycling initiative saves Dow money on electricity and water costs: the site reuses 30,000 cubic meters of municipal wastewater each day and has reduced its energy use associated with water treatment by 95 percent. As an additional environmental benefit, this has also cut the plant’s CO2 emissions by 60,000 tons each year.

“Business value is at risk if companies do not take capital considerations surrounding water use into account, and adjust their operations accordingly,” Groot told Environmental Leader. “Efficient water management is critical to ensure industry and corporate sustainability, especially for those with high water consumption, like the chemical industry.”

This model also promotes a circular economy, where raw materials are extracted and made into products that are designed and manufactured for reuse and remanufacturing or recycling. This encourages a more sustainable model for resource consumption and manufacturing, Dow says.

“The Dow Terneuzen water reuse project is just one example of our company’s efforts to combat water scarcity,” Groot says. “By developing a strategy to implement a robust water system with a large number of industrial, urban and rural partners in the region, Dow Benelux (The Netherlands) is able to provide local stakeholders with access to water at an affordable cost. The goal of this project is to develop low-cost applications to utilize local raw water sources for reuse purposes, thereby saving precious fresh water sources for human consumption.”

The public-private partnership originated in the late ’90s. Dow wanted to expand the facility’s production but was limited by freshwater availability. Dow teamed up with Evides Water Co. to design a new, energy-efficient water purification system and began evaluating various water reuse options. Dow wouldn’t say how much the system cost, just that savings amounted to about $1.5 million annually compared to the next best option, and that the different partners each invested in part of the infrastructure, facilities and purification technologies.

“These contacts paved the road for the cooperation that materialized a few years later when the city of Terneuzen, its municipal water board and Dow came together to create this public-private approach to water management,” Groot says. “Dow and its partners are twice reusing the community’s treated wastewater through an innovative wastewater recycling program, using every liter of water three times instead of once.”

Today, Dow Terneuzen accepts 10,000 cubic meters of municipal household wastewater — purified by Evides — each day. The chemical plant uses the wastewater to generate steam and feed its manufacturing plants. After the steam is used in the production processes, the water is used again in cooling towers until it finally evaporates into the atmosphere.

Compared to the energy cost needed for conventional seawater desalination, Dow Terneuzen has reduced its energy use by 95 percent by recycling the city’s wastewater, Groot says.

“Ninety percent of the energy use reduction was achieved by switching from thermal desalination to membrane separation,” he explains. “Another 50 percent was reduced by using municipal effluent instead of seawater as the raw water source, as lower salt contents require less pump pressure to remove the salt constituents from the water. Usage and cost for chemical treatment of membrane systems were also cut in half, thanks to the lower salt content of the municipal effluent.”

Dow has taken a similar approach to reusing wastewater at its Freeport, Texas facility, which uses city of Lake Jackson wastewater to produce steam. The Freeport plant, Dow’s largest production facility globally, is also the site of a pilot project with the Nature Conservancy to assess the value of freshwater to business by analyzing nature-based approaches, such as watershed management, to business challenges.

“The first step is to reduce consumption and be more efficient, and recycle water where possible,” Groot says. “Used materials can be maximized through reuse, mechanical recycling, chemical transformation, energy recovery, and composting, with those options presented in the approximate order of their economic value and environmental impact. However, if we are to truly bring solutions to meet the global water challenge, then we must move beyond our linear economy models, where we ‘take, make and dispose’ of raw materials, to a circular economy where we close the resources loop.”

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