Recycling Treated Municipal Wastewater for Industrial Water Use

Section 1: Introduction
Recycling Treated Municipal Wastewater for Industrial Water Use
Agricultural
In many states, agricultural irrigation is a significant percent of the total water demand and is estimated to
represent 40% of the total water demand nationwide [Solley et al, 1998]. Recycled wastewater has been
used to irrigate a variety of agricultural applications including: pasture; orchards and vineyards; harvested
feed, fiber and seed; food crops; processed food crops; and nursery and sod. Florida uses 19% of its
recycled wastewater supply for agricultural irrigation [Florida Department of Environmental Protection,
2002] and California uses approximately 48% [California State Water Resources Control Board, 2002].
Environmental and Recreational
Recycled wastewater has been used for environmental improvements and recreational uses.
Environmental reuse includes wetland enhancement and restoration, creation
of wetlands for wildlife habitat, and stream augmentation. Wetland reuse
projects often include dual goals: to enhance downstream surface water
quality and create additional wildlife habitat. Recreational applications for
recycled wastewater include water impoundments restricted to boating and
fishing, smaller landscape impoundments, and golf course ponds.
Ground Water Recharge
Ground water recharge using recycled wastewater has been used to reduce
saltwater intrusion in coastal aquifers, augment potable or nonpotable
aquifers, provide storage and/or further treatment of recycled wastewater for
later use, and prevent ground subsidence. In areas with extensive agricultural
irrigation, ground water recharge practices rely on the aquifers for storage, removing the need for storage
facilities to meet seasonal demands.
Augmentation of Potable Supplies
Potable water supplies can be supplemented with treated wastewater by surface water augmentation,
ground water recharge, and direct potable reuse. The first two applications are indirect potable reuse,
which has been defined as the augmentation of a community’s raw water supply with treated wastewater
followed by an environmental buffer [Crook, 2001]. In this case, the treated wastewater is mixed with
surface and/or ground water and receives additional treatment prior to entering the potable water
distribution system. Direct potable reuse is defined as the introduction of treated wastewater directly into
a water distribution system without intervening storage (pipe-to-pipe) [Crook, 2001]. There are no direct
potable reuse applications in the U.S.
1.4 Wastewater Recycling in Minnesota
Setting and Drivers
Minnesota is known for its abundance of water, as the “Land of 10,000 Lakes.” A safe, cost-effective, and
adequate water supply has been easily attained for many Minnesota industries and communities, but there
are some regions where water quality is impaired or declining or where water supply is limited. Section 2
provides additional information about these areas. Minnesota’s environmental stewardship ethic has
promoted the need to conserve water resources and programs have been implemented across the state.
Conservation has gone hand-in-hand with improved water protection programs and more stringent
regulations for surface water dischargers. In the future, residential and industrial growth in some areas of
Minnesota could potentially be curtailed because of a limited water supply, even with more stringent
conservation practices. Alternative supplies will be sought – and treated wastewater effluent is one
potential supply.
Water quality considerations may also drive more wastewater recycling in Minnesota. As growing
communities generate additional wastewater, there will be a need to provide higher and higher levels of
wastewater treatment to maintain or decrease the discharge loads to the state’s waterways. Finding other
uses for the treated wastewater, through partnerships with industry, will decrease wastewater discharges.
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