1. Deep Bed Denitrification Performance
Cold Weather Operation for Two Northeast WWTPs
Presented by: Gary M. Lohse, P.E., Severn Trent Services
Ken Wineberg, Severn Trent Services

2. The Nitrogen Cycle via Biological Processes
ORGANIC NITROGEN
(Proteins, Urea, etc.)
Bacterial
Decomposition
& Hydrolysis
AMMONIA NITROGEN
ORGANIC NITROGEN
(Bacteria Cells)
ORGANIC NITROGEN
(Net Growth) O2
Lysis & Auto Oxidation
NITRITE (NO2-) O2
NITRATE (NO3-)
Denitrification
NITROGEN GAS (N2)
Organic Carbon

3. Deep Bed Denitrification Filter General Overview
Dissolved nitrate (NO3) is converted to nitrogen gas (N2)
Heterotrophic bacteria
- Use the O in NO3- as final e- acceptor when free dissolved O2 is not available (anoxic environment)
- Need organic carbon source for energy and cell-building
- Easy to stop and start
- Prefer pH range is neutral – works in range of ~ 6.0 to 8.2
- Need nutrients such as P, often already available in wastewater
- Reaction rate affected by temperature, carbon source & potential toxins

4. Deep Bed Denitrification
Severn Trent Services 4

5. Deep Bed Denitrification Filter - Profile of Components
Media
Support Gravel
Underdrain
BW Air Header
BW Air Lateral
Sump Cover Plate
Sump

6. Deep Bed Denitrification Filter - Underdrain system
Support Media and Gravel
Handle Hydraulic Shocks – minimize possible damage to filter internals
Minimize Potential Pluggage in Applications with High Solids Loading or Biological Activity
Collect Filtrate in Normal Operating Mode
Helps Evenly Distribute BW Air & Water Across Entire Area of the Filter Bed

7. Deep Bed Denitrification Filter - Air & Water Flow through underdrain
Downflow Operating Mode
Upflow Backwash Mode

8. Deep Bed Denitrification Filter - Air & Water Distribution System
Stainless Steel Box Header
Air Laterals, Stainless Steel
Protected from Gravel & Media
Located Under Snap T BlockTM Arch
Located under every other row
Water Slot in Sump Cover
Located under every other row, where there is no air lateral

9. Deep Bed Denitrification Filter - Methanol (carbon) System
Tank Volume Standard Day Average Flow
Tank Continuous Level Measurement
Tank Low and High Level
Methanol Pumps
Diaphragm
Peristaltic

10. Supplemental Carbon Control
Flow Meter
Influent
Denitrification
Filters
Effluent FE
Influent
Sample
Nitrate
Analyzer
Effluent
Sample
Controller
(MMI)
Carbon
Feed Pump

11. Deep Bed Denitrification Filter - Backwash (Solids Removal)
3 Basic Cycles
 Backwash Air Only:
- 1 to 3 min
- Backwash Air Rate of 5 CFM/ft2
 Backwash Air/Water Scour:
- 10 to 15 min (trough overflow time)
- Backwash Water Rate of 6 GPM/ft2
 Backwash Water Only Rinse:
- 5 min

12. Deep Bed Denitrification Operation- Filtration

13. Deep Bed Denitrification Operation - Clearwell

14. Deep Bed Denitrification Operation – Air Backwash

15. Deep Bed Denitrification Operation – Water Backwash

16. Deep Bed Denitrification Operation – Air/Water Backwash

17. Deep Bed Denitrification Operation - Mudwell

18. Factors Affecting Denitrification Filter Design
Influent NO3-N Concentration
Dissolved Oxygen (DO) Concentration
 Low DO Preferred
Carbon Source Characteristics & Availability
Alkalinity: 50 PPM+ Preferred
pH Range: Preferred
 Optimum
Presence of Nutrients and/or Toxins
Temperature
Reaction Time: Empty Bed Detention Time (EBDT)

19. Scituate, Massachusetts Commissioned in 2000

20. Scituate, Massachusetts

21. Denitrification Filter Design Criteria
Design Value
Average flow: mgd
Max day flow: mgd
Peak hour flow: mgd
Average TSS: 15 mg/L
Average NO3-N: 13 mg/L
Temperature: 8 deg Celsius
Plant Effluent
TSS: 5 mg/L
NO3-N: mg/L
TN: 4 mg/L
Denitrification Filters
Average hydraulic loading 1.22 gpm/sf
Peak hydraulic loading 3.30 gpm/sf
12 month rolling average

22. Methanol System
Scituate WWTP
Filter System

23. Average Operating Data April 2001Through November 2006
Flow Rate
Average: mgd
Max day: mgd
Peak hour: mgd
Plant Effluent (Average)
CBOD: mg/L
TSS: mg/L
TN: mg/L
Denitrification Filters
Average hydraulic loading: 0.70 gpm/sf
Peak hydraulic loading: 2.40 gpm/sf
12 month rolling average

24. Cold Temperature Operating Data Scituate WWTP April 2001 Through November 2006
Flow
(mgd)
WW Temp
(deg C)
CBOD
(mg/L)
TSS TN
Dec
1.45 13
2.5
5.2
2.40
Jan
1.40 11
2.1
3.5
3.11
Feb
1.26 10
2.4
3.8
2.47
Mar
1.34
3.7
3.3
2.50
Apr
1.60
3.1
4.5
2.76
May
1.47
3.0
4.1
3.20
Average
1.42
11.3
2.8
2.74

25. Cold Temperature Operating Data Scituate WWTP Dec 2006 Through May 2007
Flow
(mgd)
WW Temp
(deg C)
Influent
NO3-N
(mg/L)
Effluent
Dec 06
1.18
11.3
10.1
0.33
Jan 07
1.23
9.2
11.2
0.30
Feb 07
0.94
7.6
12.2
0.18
Mar 07
1.57
8.7
8.8
0.38
Apr 07
2.12
9.4
6.9
0.49
May 07
1.43
12.7
8.0
0.48
Average
1.41
13.0
9.5
0.36

26. Allegany County, Maryland Celanese WWTP Commissioned in 2005

27. Allegany County, MD Celanese WWTP
2.86 MGD Design
Clarifiers
Single Stage
Activated
Sludge
Denitrification
Filters
Head
Works

28. Denitrification Filter Design Criteria
Design Value
Average flow: mgd
Max Month flow: mgd
Peak hour flow: 6.6 mgd
Average TSS: 30 mg/L
Average NO3-N: 26 mg/L
Temperature: 11 deg Celsius
Plant Effluent
TSS: 5 mg/L
NO3-N: 2 mg/L
TN: 3 mg/L
Denitrification Filters
Average hydraulic loading 2.6 gpm/sf
Peak hydraulic loading 6.0 gpm/sf
Annual Average

29. Cold Temperature Operating Data Celanese WWTP Dec 2009 Through May 2012
Flow
ADF
(mgd)
WW Temp
(deg C)
CBOD
(mg/L)
TSS
NOx-N TN
Dec
1.70
12.5
2.0
3.3
1.7
3.7
Jan
1.68
11.5
3.0
1.6
Feb
1.78
10.9
2.3
1.1
Mar
2.11
10.6
2.7
0.7
Apr
1.71
11.9
4.3
0.4
1.8
May
1.64
12.9
4.0
1.4
Average
1.77
11.7
3.1
2.9
1.0

30. Additional Cold Weather Deep Bed Denitrification filters
New York – 2
Pennsylvania – 2
Maryland – 5
Virginia – 8
Massachusetts – 4
Colorado – 1
California – 2 (High Elevations)

31. Conclusion
Deep beds allow maximum ability for solids to be captured providing for consistently low TSS and turbidity effluents with a varying load of TSS
Filter media becomes attachment site for denitrifying bacteria in which dissolved nitrate (NO3) is converted to nitrogen gas (N2) providing nitrogen removal through a biological process
Need organic carbon source for energy and cell-building and nutrients such as P, often already available in wastewater
Backwash water is typically only 2 – 4 % of forward flow. Lower backwash consumption and recycle cuts plant operating costs and increases plant capacity.
Reaction rate affected by temperature, carbon source & potential toxins
Deep Bed Denitrification filters can achieve TSS of below 4 mg/l and TN limits of below 3 mg/l even in cold climates

32. Cold Weather Deep Bed Denitrification Filters
Questions??????
CONTACT:
Gary M. Lohse, P.E.
Regional Sales Manager
Severn Trent Services
3000 Advance Lane
Colmar, Pa 18915
Cell: (215)
Direct: (215)
Fax: (215)