Recycling Treated Municipal Wastewater for Industrial Water Use

Section 1
Introduction
Craddock Consulting Engineers
In Association with CDM & James Crook 1-7
TM1-Sec1_0707.doc
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 Reuse in Minnesota
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 with an
abundance of poor quality water or a limited supply of high quality water. Section 3
highlights these areas in the watershed inventories. Over the past two decades,
Minnesota’s environmental stewardship 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. As we look to 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 for a specific area, industry, or group of industries.
Water quality considerations may also drive an increased role for reuse 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.
The urgency for the water quality consideration is driven by the development of the
Total Maximum Daily Load (TMDL) program in Minnesota which will affect the
discharge allocations for many communities. For example, the Lake Pepin TMDL will
affect nearly two-thirds of the state. With a potential reduction requirement of onehalf
the phosphorus and solids loads to Lake Pepin, and nonpoint source reduction
practices still untested, it is likely that point source reductions will be part of the
solution. Wastewater reuse may be a cost-effective solution for some communities,
particularly when tertiary treatment processes are required to meet receiving stream
discharge limits. If these communities are also experiencing water supply limitations,
the benefits of a wastewater reuse option could be even more pronounced.