Transcript Activated Slduge Process Control

Using the CPE Approach to
Optimize Industrial Waste
Treatment Facilities
Ronald G. Schuyler and Michael Rothberg
Rothberg, Tamburini, and Winsor, Inc.
Denver, CO
And
Deb Skirvin, Steve Hamilton and Kelly Peters
Hercules Incorporated, Louisiana, MO
RTW
Coauthors
•
•
•
•
Mike Rothberg, RTW
Deb Skirvin, Hercules
Steve Hamilton, Hercules
Kelly Peters, Hercules
Comprehensive Performance
Evaluation *
• CPE - Evaluation Phase
• Design, administration, operation, maintenance
• Assess capability of major unit processes
• Identify performance limiting factors
• CCP - Composite Correction Program phase
• Systematic approach
• Eliminate factors inhibiting performance
*Hegg, DeMers and Barber
CPE Process
• Originally designed for municipal facilities
• Evaluation approach
• Major unit process criteria
• Administration, design, operation, maintenance factors
• Approach applied to industrial facilities
• Revised loading criteria
• Same biological, chemical and physical laws
• Apply them to minimize poor performance
Procedure
•
•
•
•
•
•
•
Become familiar with existing facility
Define present plant loadings
Define major unit process characteristics
Define present operating conditions
Suggest process control modifications
Suggest simple process modifications
Identify longer-term oriented modifications
Communications
• Operation/consultant staffs side-by-side
• Lab
• Control room
• On/in the tanks
•
•
•
•
3-4 days
Listen to operating staff experience
Compare to accepted standards
Verify validity or suggest alternate finding
Missouri Chemical Works
Formaldehyde &
Methanol Wastes
Winter Heating
Nitroform & Storm
Summer Cooling
EQ Tank
2.7 MG
PE
Lake
Polymer
Return Sludge
Stormwater
Decant
A Tank
2.0 MG
Effluent
Recycle
Sludge Pond
Waste
Sludge
Clarifiers
Effluent
1996 Conditions
• Flow = 0.32 MGD
• Influent
• BOD = 11,190 lb/day (about 4,193 mg/L)
• COD = 23,915 lb/day (about 8,961 mg/L)
• Effluent
• BOD = 77 lb/day (about 29 mg/L)
• COD = 1,271 lb/day
• TSS = 50 lb/day (about 19 mg/L)
1996 Process Data
•
•
•
•
•
•
•
MLSS/MLVSS = 6,305/5,376 mg/L (85% vol)
RAS flow = 0.504 MGD, 160% of influent
WAS = 1,460 lb/day
MCRT = 73 days
F/M < 0.1 lb/lb
Polymer added = 283 lb/day (1995/96 Ave.)
Antifoam added = 54 gal/mo (1995-96 Ave.)
PE Lake
•
•
•
•
•
•
Flow equalization
Load equalization
Toxic materials such as formaldehyde
Slowly degradable formaldehyde derivatives
Storm water
Some volatilization of organics
EQ Basin
•
•
•
•
•
•
•
Maintained at 10-10.5’ depth
Load equalization
About 7 days DT
Received no return sludge
Aerated to control odors
25% COD removal without biomass return
No temperature control
Aeration Tank
• 20’ deep
• Parkson Biolac aeration chains
• 2.4 days detention time @ Q = 0.5 MGD
and RSF = 0.5 MGD
• MLSS about 6,000 mg/L
• Maintain temperature about 95°F (35°C)
• Volumetric loading = 32-52 lb BOD/103 ft3
Secondary Clarifiers
• 2-45’ diameter, 12’ deep
• 101 gal/ft2/day, 13.6 lb MLSS/ft2/day
• Return ratio
• Average = 160%
• Peak month = 312%
• Blanket thickness about 1-2 feet
• Periodic “black” layer required high RSF
• Polymer addition
• Average = 283 lb/day
• Peak month = 620 lb/day
Process Modifications
• Convert EQ basin to aeration tank
• Reduce MLSS in both tanks to about 3,700
mg/L
• Reduce return rate to less than 100% of Q
• Take one secondary clarifier off line
• Reduce variability of organic loading
Convert EQ Basin to Aeration
Tank
•
•
•
•
Bring some return sludge to EQ
Low temperature = lower metabolism rate
Increase aeration to maintain DO about 2 mg/L
Aeration capacity??
•
•
•
•
•
Could only use one 600 hp blower? Not enough!
Two blowers would “kick-out” both blowers
Calculations did not verify this
Started both < 70%
Plenty of air
• Reduced volumetric loading and F/M
Reduce MLSS
• Maintain about 3,750 mg/L
• Increase total biomass by 50%
• Use EQ basin
• Addresses organic/toxic/foaming shocks
• Reduce polymer dose
Reduce Return Sludge Flow Rate
• Reduced total flow to clarifiers
• Reduce polymer poundage at same dose
• Reduce solids load to clarifier
Remove One Secondary Clarifier
• Not required with lower solids loading
• Not required with less total flow (Q + RSF)
• Largest problem was with operations staff
• Always needed two clarifiers to settle sludge
• Never operated with just one
• Trial OK
+
+
+
+
Half-hour blanket readings
Back to two clarifiers if blanket rises over a foot
Raised 6” in first half-hour
Back to 1-2 feet thickness within one hour
• Have not used two clarifiers together since then
Stabilization of Organic Loading
• Long-term
• Work with production staff
• Reduce unusual discharges
• Notify operations when problem occurs
• Environmental and Production groups are
now a team!
Results
• Effluent quality improved
• Organic loads stabilized
• Secondary clarifier blankets maintained at
normal
• Chemicals saved
• Polymer
• Antifoam
• Significant monetary savings
Ja
n9
Ap 5
r- 9
5
Ju
l-9
O 5
ct
-9
Ja 5
n9
Ap 6
r- 9
6
Ju
l-9
O 6
ct
-9
Ja 6
n9
Ap 7
r- 9
7
Ju
l-9
O 7
ct
-9
Ja 7
n9
Ap 8
r- 9
8
Ju
l-9
O 8
ct
-9
Ja 8
n9
Ap 9
r- 9
9
Ju
l-9
O 9
ct
-9
Ja 9
n0
Ap 0
r- 0
0
Ju
l-0
O 0
ct
-0
Ja 0
n0
Ap 1
r- 0
1
Ju
l-0
O 1
ct
-0
1
BOD/TSS, lb/D
Effluent Quality
700
Project Initiated
Parameter
600
Month
Before After
BOD, mg/L
98
39
500
TSS, mg/L
168
56
400
TSS data is for process control, only,
and permit limits do not apply.
BOD
300
200
BOD Permit Limit
100
0
TSS
Month
Oct-01
Jul-01
Apr-01
Jan-01
Oct-00
Jul-00
Apr-00
Jan-00
Oct-99
Jul-99
Apr-99
Jan-99
Oct-98
Jul-98
Apr-98
Jan-98
Oct-97
Jul-97
10000
8000
Q
Q, MGD
18000
Apr-97
Jan-97
Oct-96
Jul-96
Apr-96
Jan-96
Oct-95
Jul-95
Apr-95
Jan-95
BOD, lb/d
Organic Load Stabilization
Project Initiated
0.7
16000
0.6
14000
0.5
12000
0.4
0.3
6000
0.2
4000
2000
0.1
0
0
BOD
Q
Month
Oct-01
Jul-01
Apr-01
Jan-01
Oct-00
Jul-00
Apr-00
Jan-00
Oct-99
Jul-99
Apr-99
Jan-99
Oct-98
Jul-98
Apr-98
Jan-98
Oct-97
Jul-97
Apr-97
Jan-97
Oct-96
Jul-96
Apr-96
Jan-96
Oct-95
Jul-95
Apr-95
Jan-95
Polymer (lb/d) or Antifoam (gal/mo)
Polymer and Antifoam Use
600
Project Initiated
500
400
300
Polymer
Antifoam
200
100
0
Summary
•
•
•
•
•
•
•
•
Initiated CPE
Made simple process changes
Reduced polymer use by average 66%
Eliminated use of antifoam
Reduced effluent BOD and TSS
Reduced influent organic load
Reduced costs significantly
Great communications and teamwork