Using Municipal Wastewater as Process Water, Power Source

Dow’s manufacturing plant in Terneuzen, the Netherlands, partnered with its local municipal water treatment plant to reuse the municipal plant’s wastewater in the manufacture of its products. The water gets a third life as steam to power the plant.

Dow Chemical released its 2015 Sustainability Report on June 27, in which it highlighted its 10-year goals and progress to date. One of the company’s goals is to reduce its fresh water consumption by 20 percent.

In a unique move that supports that goal, Dow’s manufacturing plant in Terneuzen, the Netherlands, partnered with its local municipal water treatment plant to reuse the municipal plant’s wastewater in the manufacture of its products. The water gets a third life to steam-power the plant.

The Zeeuws-Vlaanderen region, where Dow’s Terneuzen site is located, lacks a freshwater source.

“Without our dikes and levees, two-thirds of our country would be under water. For over 500 years, “sustainability” meant thinking of ways to protect our land so that our people may prosper,” said Matthijs van Meerveld, a Dow employee in the Dutch city. “We now know that sustainability means we must go beyond protecting our land and people from the ravages of floods.”

The ingenious system enables the manufacturer to produce without overconsuming the strained community freshwater supply.

How System Works

After wastewater is collected at the city plant, it is buffered in a new storage tank (see Figure 1). Buffering is necessary to accommodate variations in the supply of wastewater. Through this buffer, the water is fed through an existing pipeline and transferred 11 kilometers underneath the Terneuzen Channel to the DECO™ waste water treatment plant adjacent to the Dow manufacturing site.

Figure 1: The first stage of the wastewater recovery is buffering it in a new storage tank, which accommodates variations in the wastewater. Photo courtesy of Evides Industriewater, the Netherlands.

There it is filtered and refiltered to an ultrapure condition. The plant is equipped with an integrated membrane system that consists of a continuous microfiltration unit and a two-pass reverse osmosis unit with FILMTEC™ membranes (see Figure 2).

Figure 2: The demineralized water is distributed through the existing pipeline network to Dow’s manufacturing operations. The then-clean water is reused in the manufacturing process to make Dow’s products, and then reused a second time in the cooling tower to generate energy via steam that is released into the air.

Altogether, the factory uses approximately 450 meters purified wastewater.

Wastewater Plant

The wastewater treatment facility has been producing demineralized water, cooling tower supply water and ultrapure water for the Dow Benelux B.V. production facilities in Terneuzen since 2000. It was originally designed to desalinate estuary water, but the water source contained high chemical and biological variability, which led to operational challenges like biofouling and high maintenance costs caused by corrosion.

The existing reverse osmosis installation and related treatment facility were modified to accept the intake of the wastewater.

Using low-pressure feed pumps, process automation adjustments, and the municipal wastewater as the water source, water recovery has increased by 20 percent and operational expenses are half of a seawater-fed membrane system, the company reports. Interestingly the new system improved energy efficiency at DECO. It is using 65 percent less energy in its operation.

By 2020, it is expected that the company will eliminate its reliance on remotely sourced freshwater entirely, the company states.

This is the first time that domestic wastewater is being reused on a large scale for industrial use in the Netherlands. The initiative was awarded the Environmental Award 2007 of the Province of Zeeland (Zeeuwse Milieuprijs), the Dutch VNCI Responsible Care Award 2007, and the European Cefic Responsible Care Award 2007.

“As a Dow employee, I am proud to know that I work for a company that is aware of the needs of the outside community in addition to that of the employees,” van Meerveld said.