Recycling Treated Municipal Wastewater for Industrial Water Use

TM4: WWTP Effluent Quality
Recycling Treated Municipal Wastewater for Industrial Water Use
Ammonia (NH3)
Excess ammonia in reclaimed water is a concern for increased corrosion rates,
particularly with cooling water applications. Ammonia also promotes biological
growth and related biofouling and interferes with disinfection.
Figure 22 presents the frequency of occurrence of NH3 concentration in the effluent of
all Minnesota WWTPs. Similar information is shown in Figure 23 for WWTPs with
design capacities greater than 1 mgd. The variability of effluent NH3 is also
characterized for the following ranges: < 1 mg/L, 1-5 mg/L, 5-10 mg/L, and >10
mg/L.
The average WWTP effluent NH3 concentrations are depicted by location and facility
capacity in Figure 24 and further detailed in Figures 25-28. Approximately 15% of
Minnesota’s WWTPs have nitrogen removal processes, indicated by effluent NH3
concentrations less than 5 mg/L. This accounts for 600 mgd of the total design
capacity in the state. This also assumes that WWTPs that do not monitor for ammonia,
do not nitrify. Approximately 80% of Minnesota’s WWTPs do not measure ammonia.
Of those facilities monitoring for ammonia, 16 produce an effluent with a
concentration greater than 5 mg/L.
18 Craddock Consulting Engineers
In Association with CDM & James Crook
TM4-WWTP Eff Quality_0707.doc