Recycling Treated Municipal Wastewater for Industrial Water Use

Section 5: Summary and Potential Next Steps
Recycling Treated Municipal Wastewater for Industrial Water Use
Section 5: Summary and Potential Next Steps
5.1 Summary
This study directed its inquiry into four project areas to address the project objectives.
Project Objectives
Determine the feasibility of recycling treated municipal wastewater for industrial water use in Minnesota.
Identify implementation issues associated with recycling municipal wastewater for industrial water use in
Minnesota.
Demand and Supply Analysis
There is adequate treated wastewater supply to meet industrial water demand in some regions of the
state. The Twin Cities metro area has more supply than demand and some larger industries in smaller
communities cannot fulfill their demand with
Project Areas
the available treated wastewater supply.
The largest industrial water users are power
plants with once-through cooling systems.
River water provides over 2,000 mgd of
water for once-through cooling, while ground
water provides 4 mgd for power generation
uses and 6 mgd for other industrial facility
once-through cooling water systems.
Replacing river water with recycled
wastewater does little to preserve water
supplies because the once-through cooling
process consumes little water and over 98%
Demand & Supply Analysis
Compare industrial water demands with the available
treated municipal wastewater supply.
Water Quality & Treatment Requirements
Compare industry water quality requirements to treated
municipal wastewater quality and identify treatment
processes for recycled wastewater use by industry.
Costs
Estimate treatment and transmission costs.
Implementation Issues
Identify implementation issues.
is returned back to the river. There is also no added benefit to the receiving stream from reduced
pollutant loadings, because the recycled wastewater is discharged back to the watershed. In addition,
these facilities typically require more water than can be supplied by WWTPs.
Statewide in 2004/2005, municipal WWTPs produced 425 mgd on average, and the non-power
industrial water demand, excluding power plant surface water demand, was an estimated 445 mgd.
Industrial demand for ground water was 60 mgd.
The largest industry use of ground water is for the industry sectors of food, petroleum, chemical, and
ethanol processing, along with once-through cooling systems for a range of industries. These
industry/use categories use over 40 mgd of water and it is estimated that at least half of this total, or 20
mgd, is for cooling water use.
Water Quality & Treatment Requirements
Wastewater recycling treatment technologies are available to protect public health and meet all
industry water quality requirements.
Industrial water quality requirements can be met by adding new treatment processes or upgrading
existing ones at municipal WWTPs.
The constituents of concern with the broadest implications for Minnesota industrial water uses are
hardness and dissolved salts. Minnesota waters tend to be hard and high in dissolved salts and
concentrations increase in the wastewater through domestic, commercial and industrial practices.
Advanced secondary wastewater treatment processes do not remove hardness and dissolved salts;
tertiary treatment processes will be required if these constituents are to be removed.
The data routinely monitored by WWTPs do not provide all the water quality data for a complete
assessment of WWTP effluent as an industrial water supply without new monitoring being performed.
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