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

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

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

Deep Bed Denitrification Severn Trent Services 4

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

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

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

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

Deep Bed Denitrification Filter - Methanol (carbon) System Tank Volume Standard 21-30 Day Supply @ Average Flow Tank Continuous Level Measurement Tank Low and High Level Methanol Pumps Diaphragm Peristaltic

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

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

Deep Bed Denitrification Operation- Filtration

Deep Bed Denitrification Operation - Clearwell

Deep Bed Denitrification Operation – Air Backwash

Deep Bed Denitrification Operation – Water Backwash

Deep Bed Denitrification Operation – Air/Water Backwash

Deep Bed Denitrification Operation - Mudwell

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: 6-8.2 Preferred  7.0-7.5 Optimum Presence of Nutrients and/or Toxins Temperature Reaction Time: Empty Bed Detention Time (EBDT)

Scituate, Massachusetts Commissioned in 2000

Scituate, Massachusetts

Denitrification Filter Design Criteria Design Value Average flow: 1.60 mgd Max day flow: 2.36 mgd Peak hour flow: 4.34 mgd Average TSS: 15 mg/L Average NO3-N: 13 mg/L Temperature: 8 deg Celsius Plant Effluent TSS: 5 mg/L NO3-N: 0.5 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

Methanol System Scituate WWTP Filter System

Average Operating Data April 2001Through November 2006 Flow Rate Average: 1.22 mgd Max day: 3.54 mgd Peak hour: 4.20 mgd Plant Effluent (Average) CBOD: 3.1 mg/L TSS: 4.5 mg/L TN: 2.9 mg/L Denitrification Filters Average hydraulic loading: 0.70 gpm/sf Peak hydraulic loading: 2.40 gpm/sf 12 month rolling average

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

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

Allegany County, Maryland Celanese WWTP Commissioned in 2005

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

Denitrification Filter Design Criteria Design Value Average flow: 1.66 mgd Max Month flow: 2.86 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

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

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

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

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) 859 - 3814 Direct: (215) 997-4052 Fax: (215) 997-4062 Email: glohse@severntrentservices.com