Recycling Treated Municipal Wastewater for Industrial Water Use

Section 3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
meet the anticipated water requirements for much of Minnesota’s industrial water demand, additional
treatment at the WWTP or the industry site will be required. For example, some cooling water
applications will require a softening process to reduce hardness and dissolved salts.
Alternative Recycled Wastewater Treatment Costs
The cost to treat WWTP effluent water beyond the base level processes is estimated to be $1.25 -
$5.00/1000 gallons for a 0.5 mgd
supply, $1 - $4.00/1000 gallons for a 1
mgd supply, and in the range of $0.50
- $3.00/1000 gallons for a 30 mgd
supply. Table 3.8 and Figure 3.5
summarize the costs for flows from
0.1 to 30 mgd for each of the tertiary
reclaimed water classifications. These
costs are for treatment in addition to
the base system treatment,
transmission, and other system costs.
In comparing conventional treatment
to membrane systems to soften the
water and remove dissolved solids, the
membrane process is more expensive
except when treating smaller supplies.
However, additional credit in
microbial removal with membranes
could offset disinfection costs. Blended supplies and treatment streams could also be considered to
optimize treatment costs and meet multiple water supply needs. The lower costs of conventional treatment
for larger supplies may be underestimated because it is assumed that a WWTP has adequate land for the
treatment facilities and uses a less costly solids disposal practice, such as land application of lime sludge.
This may not be an option for some municipalities or industries.
Table 3.8. Treatment Costs for Tertiary 1 through Tertiary 4 Systems*
Cost of Service for Treatment, $/1000 gallons
Tertiary 1 Tertiary 2 Tertiary 3 Tertiary 4
Flow/
Conven- Membrane Membrane Ion
Demand, mgd tional Filtration Softening Exchange GAC UV
0.1 6.90 2.90 4.85 6.15 7.75 5.25
0.5 2.20 1.30 2.70 3.65 4.80 3.00
1 1.70 1.10 2.40 3.30 3.70 2.55
1.5 1.40 1.00 2.30 3.15 3.35 2.40
2 1.20 0.95 2.25 3.10 3.15 2.35
3 1.05 0.95 2.20 3.05 3.00 2.25
4 0.90 0.95 2.20 3.05 2.90 2.25
5 0.80 0.90 2.15 3.00 2.80 2.20
10 0.60 0.80 2.00 2.85 2.60 2.10
15 0.50 0.75 1.95 2.80 2.50 2.00
30 0.45 0.70 1.85 2.70 2.30 1.90
*In addition to recycled wastewater base system costs
Figure 3.5. Treatment Costs for Tertiary 1 through Tertiary 4
Processes
Cost of Service, $/1000 gallons
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Treatment Systems
T=Tertiary; Levels 1-4
T1-Conventional
T2-Membrane Filtration
T3-Membrane Softening
T4-Ion Exchange
0.1 0.5 1 1.5 2 3 4 5 10 15 30
Recycled Wastewater Flow/Demand, mgd
Metropolitan Council Environmental Services 51
T4-GAC
T4-UV