Marshalltown Wastewater Treatment Plant Phosphorus Removal Upgrade

1. Marshalltown Wastewater Treatment
Plant Phosphorus Removal Upgrade
Iowa State University
Steven Dickey
Dan Fleege

2. Overview
• Marshalltown overview
• Problem statement and proposal
• Biowin modeling results
• Recommendation
• Questions

4. Marshalltown, Iowa
Marshalltown
Des Moines

5. Marshalltown Water Pollution Control
Plant
• Began service in 1940
• Currently serves 26,000 people
• Plant divided into 2 processes
– Mechanical plant to treat municipal waste
– Sequencing Batch Reactor to treat hog waste
• Effluent combined before UV disinfection
• Methane capture from stabilization basins
• Sludge land applied after stabilization

6. Population Projection

7. Mechanical Plant 1

8. Mechanical Plant 2

9. Mechanical Plant 3

10. Sequencing Batch Reactor Plant

17. Aging Infrastructure

22. Problem Selection and Goals
1.0 mg/L effluent limit for total phosphorus
• Minimize construction by utilizing existing
process equipment and configuration where
possible
• Meet simulated permit limits for phosphorus
• Biowin v3 Model similar or better effluent
• Flexibility for plant operator

23. SBR Plant Proposal

24. SBR Plant
• Need
– 1.6 MGD wastewater from a local hog processing
plant
– Hog waste caused “foaming” in biological
reactors
– High Organic Nitrogen Content: 200 mg/L
• Two Sequencing Batch Reactors
– Operational in 1992
– 2 MGD capacity

25. Current SBR Configuration
Influent Effluent
Stage 1 Stage 2 Stage 3 Stage 4
Anaerobi Aerobic Settle Decant
c 120 min 60 min 60 min
120 min
Total Cycle Time: 360 min (6 hr)
Current 15 – 25% P removal

26. SBR During Aeration

28. SBR During Settle/Decant

29. SBR During Settle/Decant

30. SBR with BPR Process
Table 8‐25 Metcalf & Eddy Wastewater Engineering
System Properties
• Anaerobic HRT: 1.5 ‐ 3 hr • SRT range: 20 ‐ 40 days
• Aerobic HRT: 2 ‐ 4 hr • Settle/decant: 2 hr
• Anoxic HRT: 1 ‐ 3 hr
• HRT range: 6.5 ‐ 12 hr

31. Proposed SBR Process
Influent Alum Addition Effluent
Stage 1 Stage 2 Stage 3 Stage 4 Stage 3 Stage 4
Anaerobic Aerobic Anoxic Aerobic Settle Decant
120 min 180 min 110 min 10 min 60 min 60 min
Cycle time: 540 min = 9 hr
HRT range: 6.5 – 12 hr

32. Expected Performance
SBR
Flow VSS TSS BOD TKN NH3‐N Total P
(MGD) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Influent 1.66 308 367 372 200 160 34
• Process cannot be simulated in Biowin
• BOD:P ratio 18:1
• Compare to Metcalf and Eddy ratios
• Expect 40 ‐ 60% P Removal

33. Process Comparison
Existing SBR Process Proposed SBR Process
• 2 MGD capacity • 1.33 MGD capacity
• Note: 1.6 MGD average • 33% flow diversion to
annual flow Mechanical Plant
• 5 Stages • 7 Stages
• No anoxic phase • Anoxic phase
• Total cycle time: 6 hr • Plant operator flexibility
• No flow diversion to – Max cycle time: 9 hr
Mechanical Plant – HRT range: 6.5 ‐ 9 hr
• 10 – 25% P removal • 40 – 60% P removal

34. Mechanical Plant Design
• Treats municipal waste
• Conventional activated sludge system divided
into 3 separate plants
• 14 MG Equalization basin
• 14 MGD firm capacity for facility
• Modifications in 1965, 1972, 1982, 1987 and
2001

35. Plant 1 and Plant 2 Identical

36. Biological Process Plan View
Tank 1
Tank 2
Final
Tank 5
Clarifier
Tank 3
Tank 4
• Tank 1‐4: 90ft x 19ft x 12ft (27.4m x 5.8m x 3.7m)
• Tank 5: 42 ft x 84 ft x 13 ft (12.8m x 25.6m x 4m)
• Total available volume: 128,000 ft³

37. Plant 1 Flow Diagram
Waste Activated Sludge
Return Activated Sludge
P
Influent Aerobic
Aerobic Aerobic
Influent Final
Clarifier
Influent Aerobic
Influent Aerobic
Effluent
Influent
Flow Splitter

38. Flow Distribution
Jetflow Injection Points

39. Mechanical Plant 3

40. Plant 3
• No modifications
• Still available for periods of high flow
• Available to reduce ammonia‐N levels if
necessary
• Alum addition to treat Phosphorus

41. BPR Systems Considered
• Anaerobic‐Anoxic‐Oxic (A2/O)
• Virginia Initiative Plant (VIP)
• University of Cape Town (UCT)
• Bardenpho™ (5‐stage)
• Initial evaluation
– Compare HRT to available tank volume
– Eliminated UCT and Bardenpho ™ processes

42. Preliminary VIP and A²/O Comparison
VIP A²/O
Benefits Benefits
• Good nitrogen removal • Good nitrogen removal
• Low oxygen requirement • Low oxygen removal
• Higher Phosphorus • Lower HRT
Removal • Less Reactor volume
required
• More process flexibility
Drawbacks
• Additional Recycle Line Drawbacks
required • Less phosphorus removal
• Higher HRT capability

43. BOD:P Ratio Comparison
BPR Process BOD/P ratio
VIP 15‐20
A2/O 20‐25
Table 8‐24 Metcalf & Eddy Wastewater Engineering
Max Month Flow Average Annual
BPR Process BOD/P Flow BOD/P
Mechanical Influent 56 39
Mechanical with 33% SBR 44 28
Influent

44. VIP Process Outline
Table 8‐25 Metcalf & Eddy Wastewater Engineering
System Properties
• Anaerobic HRT: 1 ‐ 2 hr • SRT range: 5 ‐ 10 days
• Anoxic HRT: 1 ‐ 2 hr • RAS: 80 ‐ 100%
• Aerobic HRT: 4 ‐ 6 hr • Anoxic recycle: 100 ‐ 200%
• HRT range: 6 ‐ 10 hr • Aerobic recycle: 100 ‐ 300%

45. VIP Process Plan View
Anaerobic
Anoxic Final
Aerobic
Clarifier
Aerobic
Aerobic
Flow Splitter

46. VIP Flow Diagram
Waste Activated Sludge
Return Activated Sludge
P
Anaerobic
P Anoxic P
Aerobic Final
Clarifier
Aerobic
Aerobic
Influent Effluent
Flow Splitter

47. A2/O Process Outline
Table 8‐25 Metcalf & Eddy Wastewater Engineering
System Properties
• Anaerobic HRT: 0.5 ‐ 1.5 hr • SRT range: 5 ‐ 25 days
• Anoxic HRT: 0.5 ‐ 1 hr • RAS: 25‐100%
• Aerobic HRT: 4 ‐ 8 hr • Internal Recycle: 100‐400%
• HRT range: 5 ‐ 10.5 hr

48. A2/O Process Plan Layout
Anaerobic
Anoxic Final
Aerobic
Clarifier
Aerobic
Aerobic
Flow Splitter

49. A²/O Flow Diagram
Waste Activated Sludge
Return Activated Sludge
P
Anaerobic
Anoxic P
Aerobic Final
Clarifier
Aerobic
Aerobic
Influent Effluent
Flow Splitter

50. BPR Model Performance
Max Month Influent
Flow VSS TSS BOD TKN NH3‐N Total P
(MGD) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Projected
10.5 196 249 213 26 11 5.0
Mechanical
Max Month Effluent
VSS TSS BOD COD TKN NH3‐N Total P
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
VIP 5.1 7.6 3.6 34 2.9 0.93 0.56
A2/O 7.1 11 4.0 37 2.8 0.71 0.75

51. BPR Model Performance
Average Annual Influent
Flow VSS TSS BOD TKN NH3‐N Total P
(MGD) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
Projected
7.5 162 206 185 35 11 5.0
Mechanical
Average Annual Effluent
VSS TSS BOD COD TKN NH3‐N Total P
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
VIP 11 14 5.0 25 4.3 2.2 0.86
A2/O 5.3 7.5 3.7 30 3.5 0.87 0.79

52. Equipment Requirements
VIP A2/O
• 4 Additional recycle pumps • 2 Additional recycle pumps
• Power: 450 HP • Power: 400HP
• 6 New Recycle Pipes • 2 New Recycle Pipes
• 3000 Siemens DualAir® • 3000 Siemens DualAir®
Diffusers Diffusers
• 16 Hayward Gordon ST® • 16 Hayward Gordon ST®
Mixers Mixers

53. Chemical Treatment
• Alum addition considered for all plants
• A²/O required no alum addition for any
model simulation
• VIP process required alum addition during
winter months
• SBR requires a constant chemical addition

54. Mechanical Plant: Current Flow
Average Annual Flow Max Month Flow
Biological Alum Dosage Biological Alum Dosage
Removal Removal
ppd ppd
Percentage Percentage
1.5 2.0 1.5 2.0
0 399 532 0 530 707
10 359 478 10 477 636
20 319 425 20 424 565
30 279 372 30 371 495
40 239 319 40 318 424
50 199 266 50 265 353
60 159 213 60 212 283
70 120 159 70 159 212
80 80 106 80 106 141
90 40 53 90 53 71
100 0 0 100 0 0

55. Mechanical Plant: Projected Flow
Average Annual Flow Max Month Flow
Biological Alum Dosage Biological Alum Dosage
Removal Removal
ppd ppd
Percentage Percentage
1.5 2.0 1.5 2.0
0 480 640 0 626 835
10 432 576 10 563 751
20 384 512 20 501 668
30 336 448 30 438 584
40 288 384 40 376 501
50 240 320 50 313 417
60 192 256 60 250 334
70 144 192 70 188 250
80 96 128 80 125 167
90 48 64 90 63 83
100 0 0 100 0 0

56. SBR Plant
Existing Process Proposed Process
Biological Alum Dosage Biological Alum Dosage
Removal Removal
ppd ppd
Percentage Percentage
1.5 2.0 1.5 2.0
0 727 970 0 486 648
10 655 873 10 438 584
20 582 776 20 389 519
30 509 679 30 340 454
40 436 582 40 292 389
50 364 485 50 243 324
60 291 388 60 195 259
70 218 291 70 146 195
80 145 194 80 97 130
90 73 97 90 49 65
100 0 0 100 0 0

57. Comparative Analysis
Qualitative Cost Analysis
Initial Cost Operational
A2/O $$ $
VIP $$$ $$
Chemical $ $$$
Operational Performance
Flexibility Simplicity
A2/O ** **
VIP * *
Chemical *** ***

58. Recommendation
Implement A²/O system
• Lowest relative cost
• Most operator flexibility
• Least construction required
• Capable of meeting effluent standard
• Better ammonia‐N removal in winter models

59. Design Objective Achieved?
• Minimum construction
– SBR system remain physically unaltered
– Construction in areas of aging concrete
– Only two new recycle pumps needed for the
recommended A2/O design
• A2/O meets proposed permit limits
• Flexibility for plant operator
– Recycle rates
– SRT
– SBR phases

60. Special Thanks
• Lance Aldrich ‐ Design information
• Eric Evans ‐ Biown
• Kris Evans ‐ Mentor
• Fred Beyer
– Monthly monitoring reports
– Plant tours
– Design information
• IWPCA

62. Questions?