Recycling Treated Municipal Wastewater for Industrial Water Use

Section 2: Recycled Wastewater Demand & Supply
Recycling Treated Municipal Wastewater for Industrial Water Use
WWTPs. Larger WWTPs are defined in this study as WWTPs with permitted capacities greater than or
equal to 1 mgd and smaller WWTPs have permitted capacities less than 1 mgd. The permitted capacity is
the capacity defined in the National Pollutant Discharge Elimination (NPDES) Permit, and typically is the
design average wet weather flow. The
largest six WWTPs in the state treat over
60% of the state’s wastewater, as
represented by the plant flow ranges of 10-
50 mgd and greater than 50 mgd in Figure
2.5. Many smaller WWTPs, with permitted
capacities less than 1 mgd (not included in
Figure 2.5), discharge intermittently and
use of annual average data can be
misleading. An estimated range of annual
average flows for smaller WWTPs is
assumed in this study to be 75% of the
permitted capacity. Given a combined
design capacity of 100 mgd for the 517
WWTPs with permitted capacities less than
Figure 2.5. 2005 Annual Average Flows for WWTPs with
Permitted Capacities >1 mgd in Minnesota
Combined Annual Average Flow, mgd
1 mgd, approximately 75 mgd of treated wastewater supply could be available from smaller facilities.
Table 2.3 summarizes the capacity and historic state treated wastewater supply, based on the MPCA
Discharge Monitoring Report database (MPCA, 2005).
210
180
150
120
90
60
30
0
22
Source: MPCA, 2005
Table 2.3. Minnesota’s Available Recycled Wastewater Supply
All
WWTPs
No. of Facilities
22
17
0-1 1-2 2-5 5-10 10-50 >50
Individual WWTP Annual Average Flow, mgd
WWTPs with Permitted
Capacities >1 mgd
4
5
WWTPs with Permitted
Capacities 1 mgd and an estimate for flow from smaller WWTPs
2 WWTP flow for plants with permitted capacities