This document summarizes improvements made to secondary wastewater treatment processes at two treatment plants. At the Northside plant, instrumentation was improved in the aeration basin, including adding dissolved oxygen probes and correlating data to optimize solids retention time and wasting. At the Southside plant, process changes like increasing dissolved oxygen and return activated sludge flow enabled some ammonia removal without dedicated nitrogen removal infrastructure. Both plants saw performance benefits from improved data monitoring, process control, and solids inventory management.

1. Secondary Process Control
Past, Present, & Future
By: Roger Colee, NSWWTP Chief Operator, CFPUA
Steve Styers, SSWWTP Chief Operator, CFPUA
CFPUA Process Operators: Robert Gunter, Adam Glidden

2. Presentation
• Introduction /CFPUA Wastewater Service
Secondary Process Improvements
– Northside WWTP
• Instrumentation Improvements in Aeration Basin
• Use of Operator 10 to correlate MCRT Trends,
Wastage & Resultant Performance
– Southside WWTP
• Process Changes for NH3 removal

3. The James A. Loughlin (Northside) WWTP was designed in 1970.
Below is the 21 acre site in 1998.

4. • An Expansion/Upgrade of the James A.
Loughlin (Northside) WWTP was
completed to in 2009.

5. Old Northside Plant
Capacity & Limits
Northside Plant
Provisional Capacity &
Limits
Future Northside Plant
Capacity & Limits
Flow limit is a Monthly Average
8.0 MGD
Flow limit is a Monthly Average
10.0 MGD
Flow limit is a Monthly Average
16.0 MGD
BOD Weekly Average 45.0 mg/L
BOD Monthly Average 30.0 mg/L
BOD Weekly Average 36.0 mg/L
Monthly Average 24.0 mg/L
BOD Monthly 4/1- 10/31 5.0 Mg/L
BOD Monthly 11/1- 3/31 10.0 mg/l
TSS Weekly Average 45.0 mg/L
TSS Monthly Average 30.0 mg/L
TSS Weekly Average 45.0 mg/L
TSS Monthly Average 30.0 mg/L
TSS Weekly Average 45.0 mg/L
TSS Monthly Average 30.0 mg/L
Weekly Average Enterococci 276/100ml
Monthly Average Enterococci 35/100ml
Weekly Average Enterococci 276/100ml
Monthly Average Enterococci 35/100ml
Weekly Average Enterococci 276/100ml
Monthly Average Enterococci 35/100ml
pH >6.8 & 8.5 Standard Units
pH >6.8 & 8.5 Standard Units
pH >6.8 & 8.5 Standard Units
pH >6.8 & 8.5 Standard Units
pH >6.8 & 8.5 Standard Units
pH >6.8 & 8.5 Standard Units
Ammonia Monthly No Limit Ammonia Monthly 4/1- 10/31 16.3
mg/L
Ammonia Monthly 11/1- 3/31 32.9
mg/l
Ammonia Monthly 4/1- 10/31 1.0 Mg/L
Ammonia Monthly 11/1- 3/31 2.0 mg/L
Old NSWWTP Limits Vs. New NSWWTP Limits

6. Old Aeration System
Coarse Bubble Aeration system
A single fixed DO probe
Access to only one side for sampling & tests
Single Basin
772938 gallons
Detention Time: 2.3 hours
Target MLSS: 2000- 2200 mg/l
The old NSWWTP Aeration Basin was difficult to evaluate
and control:
The single DO probe was expensive
and difficult to maintain, so
handheld readings were taken daily.
There was no method to control air
delivery except blower output and
the valves along each drop leg.

7. New Aeration System
Membrane fine bubble diffusor system for
length of each train
Seven movable DO probes
Access to all closed cells through hatches
Four Trains by Eleven Cells each
2,095,900 – 6,868,900 gallons
Detention Time: 18 hours (3 trains open)
Target MLSS: 1800 – 2400 mg/l
The New Aeration Basin displays real time
DO readings from the plant SCADA.
• Seven fixed probes measure and display
the Dissolved Oxygen profile across the
basin.
• SCADA uses the DO readings to
maintain a DO set point across the
basin.
• SCADA also displays the air delivery
valve position and the calculated air
flow into 5 zones in the basin, all in real
time.
Physical access to all parts of the basin
surface is convenient and safe. This allows
a daily cell by cell DO profile, and sampling
can be done from all parts of each train.
Presently ammonia in mg/l is measured in
from each train’s effluent.
New NSSWWTP Aeration
Basin Improvements

8. The Aeration basin was mostly covered both for odor control, and to accommodate future
denitrification and BNR upgrades. Cells 9,10, and 11 were left open. The effluent channel has
a grated opening across it’s length because we manually operate a series of single drop
diffusers in that channel
Each of the five air valves control the flow of air sideways across the trains, so each
valve controls an identical zone in each train. The valves can be automatically
controlled by SCADA or manually set. An individual hand valve can control air to
each cell, allowing trains to be off line. This gives operations the option to rotate
trains, or choose how many trains are in operation.

9. As part of a continuing quality control effort, the process lab testing program began
several years before the upgrade in 2009. Operators at NSWWTP have tested the
following parameters continuously:
Lab and Field Tests Performed
AB Dissolved Oxygen AB Temperature AB pH
MLSS pHs RAS pHs MLSS TSS & VSS
MLSS
Temperature Readings
Ras
Temperature Readings
Oxygen Uptake Rate
Testing On MLSS
Return Activated Sludge
TSS & VSS
Waste Activated Sludge
TSS & VSS
TSS On Core Samples
From Secondary Clarifier
Settlometer Testing On
MLSS And Return Sludge
Plant Effluent
pH
Plant Effluent
SS
Plant Effluent
Ammonia
Plant Effluent
Nitrites & Nitrates
Plant Effluent Turbidity
(Critical for Future Reclaim
Potential)
Total Solids & Volatile
Solids on Primary Sludge
Total Solids & Volatile
Solids on Thickened
Sludge
Total Solids & Volatile
Solids on Press Cake

10. The lab was moved into a larger and more modern facility, that was also more
centrally located. Besides being larger, one change was that data and phone
lines were eventually connected in the new lab itself.
One of the new lab computers was connected to the CFPUA network and another was
connected to the plant SCADA. Trips across the plant to use the terminals in the
operations office are a thing of the past.
As entering the data became more physically convenient, other ways to enter, compile,
analyze and use the data from the lab results were found.
Results and images, such as microscopic examinations, are able to be transmitted to
other monitors in the plant.

11. Data was entered on a
daily report in Microsoft
Excel
Data was then transcribed
onto a dry erase board.
The data was then entered
into several parts of
Operator 10, the plant
database.
Before, at the start of 2013, the lab operator would enter his results
in several different formats.
Then the lab results were
entered in Operator 10, the
plant’s main database. The
lab operator had to enter
data in several different
parts of Operator 10, and
go to several other parts to
transcribe flows and other
needed data
Then the operator would hand
print the daily lab results on a dry
erase board. The data was indexed
by the day of the week, so
trending was still difficult. It also
made writing on the board time
consuming and awkward. The
boards strong point was the
display of lab results where
everyone could see them and they
could become familiar with typical
values and trends.
The Excel daily report,
“The Daily Solids Balance“
calculated the daily SRT ,
MCRT and F/M Ratio and
the solids inventory . Each
day the operator began a
new report and file.
Operators were very
comfortable making
wasting decisions from this
sheet, but trending
between files was difficult.

12. • Configure Operator 10 to
accept all lab testing
results in one location on
the program, then have
Operator 10 use the flow
data already entered, and
then calculate a MCRT, an
SRT, and a F/M Ratio for
each day testing is done.
Operator 10 will also
calculate related mass
values, such as pounds of
MLSS in the aeration
basin.
Change Number One

13. • Use the Operator 10 reports
function to generate a daily
report in same visual style
& data presentation that all
operators had been trained
on.
• Unlike the Excel Solids
Balance, all results in the
printed on the report are
generated by and recorded
by the Operator 10
Database.
• The report is visible to all
Operator 10 users once
complete.
Change Number Two

14. • The dry erase board was
replaced by a large (45 inch)
computer monitor.
• A new Operator 10 Dataview
was compiled to display the
lab’s results and calculations.
• With the results tabulated by
parameter, operators can look
from over a two to three week
period and see the plant’s
performance.
• Operators generate the display
and report by entering the
same data.
• Operators can also display real
time images from the lab
microscope for examination.
Change Number Three

15. How Does it Work Now?
• The lab operator enters his results into a
Operator 10 data view dedicated for that
purpose.
• Next he enters a projected amount for the plant
to waste.
• Operator 10 writes a report (in the same visual
style and format as the Excel report) that
includes the daily MCRT, SRT, & F/M ratio.
• The day’s calculations are displayed against
desired results.

16. • The report includes the
actual mass of solids in
the element, and a
calculated amount based
on the wasting
projection.
• On this report we have an
actual pounds value of
96,839 in the Aeration
basin.
• If we want to follow the
SRT target we need to
have 102,722 pounds in
the basin.
The operator can waste .210 mgd and settle for the difference between 18.00 and 16.97 days
in the SRT.
Or they can decrease wasting and try to close the gap the target and the result.
h
if

17. Then the “Door Sheet” data view from Operator 10 is updated, and displayed again
in front of the chief operator’s office.

18. What is next for the
Lab Data?
Next is tracking the lab results data against outcomes from a
predictive software program that uses a model of the NSWWTP.
Just as a meteorologist uses a
modeling program to predict a
weather outcome, we can compare
the lab results to predictions from
Biowin to fine tune a model that will
accurately predict plant
performance.

19. This gives plant operations insight on how to handle future
events, rather than relying on trial and error alone.
This Biowin model will the be able to predict plant behavior
during process control adjustments, under extreme weather
conditions, or when unusual streams are added to the influent.

20. Presentation
• Introduction /CFPUA Wastewater Service
Secondary Process Improvements
– Northside WWTP
• Instrumentation Improvements in Aeration Basin
• Use of Operator 10 to correlate MCRT Trends,
Wastage & Resultant Performance
– Southside WWTP
• Process Changes for NH3 removal

21. Southside Wastewater Plant
Background
• Originally placed into service in 1972 as a 6 MGD attached growth
secondary treatment facility. It was later expanded to a 12 MGD
attached growth facility which included the addition of a small
activated sludge tank in 1986.
• Plant treatment processes include:
– Screening
– Grit Removal
– Primary Sedimentation
– Attached Growth or Fixed Film Reactors (Trickling Filters)
– Activated Sludge
– Final Clarification
– Chlorine Disinfection
– Chemical De-chlorination

22. NPDES Requirements
• Flow - 12.00 mgd monthly average daily flow
• CBOD 5-day, 20° c < 25 mg/l (Originally permitted for
BOD 5-day, 20° c < 30 mg/l)
• Total Suspended Solids < 30 mg/l
• Ammonia (NH3) Monitor Only (Plant is not designed
for nitrogen removal)
• Enterococci (geometric mean) < 35/100 mL(weekly)
& 276/100 mL (monthly)
• pH – 6.8 - 8.5

23. Primary Clarifier

24. Trickling Filter

25. .5 MG Aeration Basin
Converted from the original 1971 6 mgd design secondary clarifier

26. Coarse Bubble Diffusers

27. Secondary Clarifier
.9 MG X 2

28. The Challenge of Decreasing NH3
• With a .5 mg aeration tank and a detention
time of one hour it was decided to encourage
limited nitrification by:
• Establishing the target MCRT, raising the D.O.
in the aeration tank and increase RAS flow.
• Improving process control techniques along
with increasing internal process control.

29. Performance Observations
• Observation and control aggressively began in
August 2013, which resulted in an average of
37% NH3 removal.
• The solids inventory was built up and
controlled by establishing a MCRT of 8 days
• This allowed naturally occurring bacteria to
grow and develop to begin the conversion of
NH3 into nitrite, nitrate.

30. NH3 Uncontrolled

31. Performance Observations
• With an increase in the mass of the bio-mass
from 22,000 lbs to 39,000 lbs, alkalinity and pH
began to drop with it reaching as low as 6.8
(permit limit).
• TSS did not pass over weirs.
• pH did not fall below 6.8
• Denitrification did not occur in secondary
clarifiers.
• NH3 was reduced to as low as 6.6 mg/l, a
reduction of 68%.

32. Performance Adjustments
• MCRT was decreased to as low as 5 days to
reduce solids inventory and raise pH values.
• Once comfortable pH levels were again
reached, MCRT was increased during the
month of October and as a result, 50 % NH3
removal efficiencies were achieved without
lowering the pH to lower permit limit.

33. NH3 Controlled

34. Changing Conditions
• With a more conducive environment in place,
the plant was able to achieve noticeable
reductions in NH3 from October through to
December.
• With the onset of the winter months and
wastewater temperatures consistently at 15°c
or lower, all attempts at nitrification have
been hindered.

35. Temperature/NH3 Relationship

36. Conclusion
 Establishing MCRT method of solids inventory
control worked for our plant in encouraging
nitrification.
 By using this method, we were able to control
and provide the environment needed for the
organisms to achieve a noticeable ammonia
reduction.
 For the future, the plant is beyond the design
stage for a 16 mgd BNR (Biological Nutrient
Removal) plant which can be expanded to 24mgd
as demand increases.