Recycling Treated Municipal Wastewater for Industrial Water Use

Section 1: Introduction
Recycling Treated Municipal Wastewater for Industrial Water Use
The total “industrial water use”, defined by the combined water use of the power generation and industrial
processing categories, is nearly 3 billion gpd, which is roughly 75% of the total major water use in the
state. Ground water supplies are used to meet approximately 60 mgd or 22,000 million gpy. If we assume
that Minnesota’s water utilities have an industrial customer demand of 10% of their total supply, then an
additional 40 mgd of ground water is used by industries. Under this assumption, the total industrial water
demand for ground water is approximately 100 mgd. This equates to the typical, potable supply use of 1
million people, given the standard residential use engineering estimate of 100 gallons/person-day.
1.3 Wastewater Recycling Background
In Minnesota, WWTP effluent is typically discharged to a receiving stream or a land application system.
However, wastewater effluent can also be beneficially used for a variety of purposes. There are various
terms used to describe the beneficial use of WWTP effluent: wastewater recycling, wastewater reuse,
water reuse, water recycling, or water reclamation are often used interchangeably.
While this project evaluates the beneficial reuse of wastewater effluent for industrial purposes, nonindustrial
uses are briefly described to indicate the full range of wastewater recycling practices. From the
perspective of the municipality, investment in capital to provide recycled wastewater will typically
involve a review of all options; multiple users are commonly required for wastewater recycling to be a
cost-effective practice for the municipal utility. Wastewater recycling in the U.S. is typically categorized
under the following major categories:
Industrial
Urban
Agricultural
Environmental and recreational
Ground water recharge
Augmentation of potable supplies
Industrial
Industrial reuse applications in the U.S. have steadily increased over the past decade, with an increasing
diversity of industrial uses. The largest use of recycled
wastewater in the U.S. has been for cooling water. The large
water demands of power facilities for cooling water and
other needs makes them an ideal facility for reuse. Recycled
wastewater is also used as process water for a variety of
applications at petroleum refineries, chemical plants, metal
working, pulp and paper mills, and other production
facilities. Another larger use of water by industries is for
washing or wetting requirements for industries such as
laundries, sand and gravel washing operations, or dust
suppression.
Urban
Recycled wastewater is used for a variety of purposes in the urban setting. One common use, that is one
of the few wastewater recycling applications in Minnesota, is for golf
course irrigation. Other typical irrigation reuse applications include:
public lands such as parks, athletic fields, highway medians and
shoulders, landscaped areas for commercial properties, and
landscaping for residential areas. Other examples of “urban” reuse
applications include vehicle washing facilities, fire protection, toilet
and urinal flushing in commercial buildings, decorative water features
such as fountains and reflecting pools, street sweeping, and dust
control and soil compaction for construction projects.
6 Metropolitan Council Environmental Services