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Recycled wastewater could provide water for industry

Here in the land of 10,000 lakes, it may be difficult for Minnesotans to accept the idea that they should be concerned about future water supply.

This year’s drought notwithstanding, it’s true that water is rarely a statewide concern today. But future growth and development — coupled with a limited or potentially dwindling water supply — could someday create local and regional supply shortages.

Concern about water supply was the impetus behind a Council study of the statewide feasibility of using recycled wastewater for industrial applications   — commonly called “water reuse.” A report of the study results was released in August.

Key study questions were:

• Can it be done?
• Where, and for what kinds of industry?
• Generally speaking, how much will it cost?
• Is it cheaper than the existing or traditional water supply?
• What implementation issues need to be addressed?

The extensive statewide study reveals that water reuse in Minnesota is indeed viable — for some industries in some locations. And it can be done in ways that protect the public health.

Water reuse is already occurring on a limited basis in a few places in Minnesota. In Mankato, for example, a new power plant was built near an existing wastewater plant. By recycling wastewater from the plant, no additional water was needed for cooling, and the power plant needed to obtain fewer permits.

Water reuse conserves critical resources

In other cities around the world where wastewater is reused more extensively as a non-potable water supply, a number of benefits have been documented. They include:

• Less depletion of groundwater for one-time use and discharge to surface waters.
• Preservation of groundwater to support growth and development.
• Reliable and potentially lower cost water supply for industry.

Bill Moore, general manager of Metropolitan Council Environmental Services (MCES), which coordinated the study, said the study represents an important step in managing water resources.

“We know that water is a limited resource and that the economic vitality of the state is dependent on it,” he said. “We may not be doing wide-scale water reuse in Minnesota tomorrow, but if it looks like it has potential for 20 years down the road, we need to plan ahead for it now.”

Report identifies areas for future study

The study, “Recycling Treated Municipal Wastewater for Industrial Water Use,” identified the 10 largest categories of water users in Minnesota — power generation, water utilities and crop irrigation, for example.

Researchers created a sequence of state maps to show the location of major industrial users and the location of large wastewater treatment plants that could supply treated effluent for industrial reuse. The maps revealed a number of good matches in terms of location and water demand.

In the metro area, 255 million gallons of treated wastewater are poured into area rivers every day, while industrial water demand is about 75 million gallons.

Statewide, 425 million gallons of wastewater are poured into surface waters every day, compared with an industrial water demand of about 442 million gallons (excluding power plants using surface water).

Economics favor larger industrial water users or clusters of users. Proximity to a wastewater treatment plant and the quality of the water an industry requires are key factors in economic feasibility. The report provides specific information for estimating costs.

Other areas of inquiry included regulatory requirements, reliability, liability and risks.

Water reuse occurs widely on both coasts

Water reuse is already widespread in many western states like California, Nevada, New Mexico and Utah. Eastern states are also in the business of reuse, including Virginia, Florida and North Carolina. Nationwide uses range from agriculture and keeping golf courses green to such diverse industries as electronics and manufacturing.

One typical application is using reclaimed water for cooling towers in the energy industry, which, in Minnesota, accounts for fully 63 percent of daily water use — 2.4 billion gallons per day.

Stakeholder meetings with representatives of industries such as Xcel Energy, CertainTeed, Great River Energy and ethanol plant designers indicated support for water reuse as a way to protect the state’s water resources while supporting its industrial sector. Although the meetings were not intended to identify potential projects, several industries indicated interest in such projects if concerns about liability were resolved and if the economics were favorable.

The study concluded that recycled wastewater is an emerging water supply and is viable for some industries. The report identified specific issues to resolve as reuse projects are developed across Minnesota and serve a larger portion of the state’s water supply needs.

Demonstration project is a likely next step

A likely next step, according to the report, would be a demonstration project that draws together industry, wastewater and water utilities, regulators, community groups and other stakeholders that – working as partners — plan, design, construct and implement a specific project.

The report, “Recycling Treated Municipal Wastewater for Industrial Water Use,” is available online or by contacting the Council's Data Center, data.center@metc.state.mn.us.

Funding for the study was recommended by the Legislative Commission on Minnesota Resources (LCMR) from the Environment and Natural Resources Trust Fund in 2005. Metropolitan Council Environmental Services as well as industries and local, regional and state agencies and organizations provided in-kind contributions of staff time and expertise.