Recycling Treated Municipal Wastewater for Industrial Water Use

TM4: WWTP Effluent Quality
Recycling Treated Municipal Wastewater for Industrial Water Use
TSS
Total suspended solids (TSS) is a gross measure of the amount of particulate in the
water. In wastewater, it is typically sand, silt, clay, organic matter, including
microorganisms. Elevated TSS levels can create deposition and clogging problems for
industrial applications. Particulate matter can also interfere with disinfection and
other processes such as reverse osmosis. Several states with water reuse regulations
require reclaimed water to meet a TSS limit of 30 mg/L for various uses.
Figure 8 presents the frequency of occurrence of TSS concentration in the effluent of
all Minnesota WWTPs in 2005. Similar information is shown in Figure 9 for facilities
with design capacities greater than 1 mgd. The variability of effluent TSS is also
characterized for the following ranges: < 5 mg/L, 5-10 mg/L, 10-20 mg/L, and >20
mg/L.
The average annual WWTP effluent TSS concentrations are depicted by location and
facility capacity in Figure 10 and further detailed in Figures 11-14. There were 100
facilities with less than 5 mg/L of TSS. Those facilities have a combined design
capacity of 380 mgd, which is 50% of the total combined capacity of all WWTPs in
Minnesota. Over 300 WWTPs, with a combined capacity of nearly 300 mgd, produce
an effluent with TSS concentrations in the 5-20 mg/L. Over 100 facilities have effluent
TSS concentrations greater than 20 mg/L.
8 Craddock Consulting Engineers
In Association with CDM & James Crook
TM4-WWTP Eff Quality_0707.doc