Recycling Treated Municipal Wastewater for Industrial Water Use

Section 3
Inventory of Major WWTPs and Potential Industrial Reuse Demands
Craddock Consulting Engineers 3-53
In Association with CDM & James Crook
WWReuseTM1_Sec 3_final.doc
The Met Council database provided a single data source for a regional inventory of
industries and their water demand. A more accurate method to identify potential
industries for a specific WWTP is the analysis of water billing records, which typically
provide enough detail to also assess any industrial seasonal water demands.
While the inventories performed on a state and watershed basis for this study do not
include all potential industrial water users, they do provide an indication of the types
of industries in the area and the types of industries that may be attracted to the area. If
it is assumed that the degree of diversity of industries in the watersheds does not
change (number of industry categories represented as listed in Table 3.27), then one
would expect to see a similar diversity in the future. Diversity of industries is an
indicator of areas that may be more advantageous for wastewater reuse. Given the
capital and O&M costs associated with supplying reclaimed water, and that costs per
gallon supplied typically decrease with increased supply, municipalities in areas with
multiple industrial customers will be more likely to invest in facilities for wastewater
reuse. If some industries have seasonal or weekly production schedules, the
fluctuations can be dampened by having a more diverse set of customers.
As indicated in Table 3.27, the watersheds with the most diverse (therefore, potential)
industrial reuse customers are the larger watersheds that have larger population
centers. The diversity criterion is only an indicator and has limitations with the data
set used in this study. Smaller communities may have other industries that are not
captured by the DNR database.
Areas with industries that have the highest ground water use are possibly better
candidates for water reuse, particularly if there are local supply issues. From Table
3.27, the watersheds with the greatest demand for ground water by major industries
are also those with the greatest land area: Mississippi River-Headwaters, Minnesota
River and Lower Mississippi River. These watersheds also have the largest reclaimed
water supply. While these watersheds do not have regional water supply issues like
those in the southwest and northeast of Minnesota, local issues and the proximity of a
diversity of industries may provide a community-specific fit for use of reclaimed
water by industries.
The other criterion used to assess areas that may favor water reuse by industries, was
the WWTP location and capacity. The more industries closer to the plant, the more
favorable a customer they are for reclaimed water. Capacity can be an indicator in its
comparison to the current plant flow rates. Plants approaching capacity may be
planning for expansion and any treatment modifications could roll in requirements
for reclaimed water. Conversely, plants with excess capacity and limited growth
potential in the area, may attract industry for its treatment capacity, and if supply is
an issue, water reuse options could be explored. This criteria is not applicable on a
broad watershed basis. However, specific WWTPs are noted in the watershed
discussion on factors influencing potential for industrial reuse.