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OBG PRESENTS:
Alphabet Soup: MBBR Ain't Exactly ENR or IFAS!Lessons Along the Way to Optimization
VA WaterJAM 2017 9/12/17 4:30-5:00PM Bill Meinert & Ned Talbot, OBG
Project Overview
Overview
M
Moving
B
Bed
B
Biofilm
R
Reactor
Fixed Biofilm / IR / TN (& some TP) Removal Fixed Biofilm + SS / IR + RAS / TN + EBio-P
I
Integrated
F
Fixed-Film
A
Activated
S
Sludge
Protected biomass on plastic media expands capacity and effluent quality
Nutrients, peak flows, cold temps
3
MBBR for Martinsburg
Benefits Obstacles
4
MBBR Piloting
Piloted September 2011 – March 2012
Warm and Cold, Dry and Wet, IR Adjustments
Air distribution and DO control (+/-), No clarification
Initial – Nitrification, startup, warm & cold (vs. Tower)
5
Comparison – DN, Tower Effluent DO & temp, Carbon
Pre- & Post-Anoxic MBBR Sizing
BOD-limited Nutrient Removal (add Carbon)
WRRF Project: MARTINSBURG, WV
3 MGD (12 MGD influent, 10 MGD peak to bio)
5 mg/L TN effluent limit
0.5 mg/L TP effluent limit
Project Summary
Demo:
Trickling filters
Nitrification tower
Modifications:
New Headworks, Biological, Ballasted Polishing
Improve Clarification, Disinfection, Anaerobic Digestion
New Solids Handling, Operations Building
Tank configuration
Minimize approach velocity (~30-35 m/hr max)
Fail safes to contain media
Physical and operational
Important Design Details
Variation between vendors
Pre-purchase / selection
7
Pre-Purchase Selection
Suez (IDI) Kruger Biowater Technology Headworks
Operational deadline – June 2016
Pre-purchased MBBR
Lowest life-cycle, capital costs
Potential change to IFAS in future
8
Martinsburg WWTP Upgrade
Simplified Process Flow Diagram
9
1. Headworks
2. MBBR
4. Co-Mag
3. Disinfection
5. Solids Handling
6. O&M, Lab
MBBR Biofilm by Zone
Diurnal VariationSolids Treatment Recycles
Seasonal FlexibilitySummer, Winter
DO ControlSetpoints, Control Valves
IR ControlMatch NO3 to BOD5
Carbon Feed ControlPost-Anoxic (& Pre-Ax?)
Process Performance by Design
10
Mix,BOD5, NO3
-> Anoxic
BOD5?, NH3
Air,BOD5?, NH3
-> Oxic
NH3
AirNH3, NO3
Oxic
NH3?, NO3
AirNH3?, NO3
Oxic
NO3
IR
Mix,NO3, Carbon-> Anoxic
TN < 5
Air
Mix,BOD5, NO3
-> Anoxic
BOD5,NO3 NH3
Mix,BOD5, NO3
-> Anoxic
NH3
AirNH3, NO3
Oxic
NH3, NO3
AirNH3, NO3
Oxic
NO3
IR
Mix,NO3, Carbon-> Anoxic
TN < 5
Air
“Summer” (more Denitrification capacity)
“Winter” (more Nitrification capacity)
11
New 5 mm screens and gritPHASE 1 (INTERIM)
HeadworksTricking Filter
Nit. TowerTank 2
Pre-Anoxic
Effluent Channel
Swing
Internal Recycle
Re-Aeration
Nitrification
Post-Anoxic
Tank 1
IR
Tank 2
INTERIM WASTEWATER TREATMENT
Keep 1 trickling filter online
Site / size restrictions
Build MBBR in 2 stages
Can also bypass Tank 1
Maintenance
Or, if media blockage
12
NEW TANKS
Allowed for “ideal” reactors
Square Zones
3-4 ft freeboard
Overflows between reactors
13
Martinsburg WWTP Upgrade
Interim Wastewater Treatment
14
Change from 8hr to 24hr composite Sampling
8-hr overnightcomposite
24-hr overnightComposite
(a 30% jump)
Headworks
Status: Constructed, Optimized
PHASE 2 (FINAL) HeadworksTank 1 + 2
Solids HandlingOperations
16
MBBR Biofilm by Zone
AirMix
BOD - Heterotrophs (H)Denitrifiers – Heterotrophs-DNNitrifiers – Autotrophs (A)
The Wrong Mix or Type of Biofilm by Zone?
Process Performance by Stage
17
“Planned”
H A A
H? H A H, A?
High Load, or Low Air
H? H? A?H A, DN?
Intermittent / Insufficient Air
Phase 1
“Planned”
Sw A AH-DN
H?H, A A H,
A?
High Load, Low Air, or no Auto
H? H? A?H A, DN?
Intermittent / Insufficient Air
Phase 2
H-DN
H-DN
H-DN?
Construction Staging, Startup, Optimization(Lessons Learned)
MBBR Equipment Pre-Purchase Challenges
Timing of Equipment Delivery
Storage During Phasing
Vendor Controls Engineer Turnover
Lack of Vendor Startup Support
Contract Coordination
Phase 1 StartupJune 2015
Initial Startup
• PE Split between TF and MBBR
• All flow to Nitrification Tower
• Coagulant to PC – remove BOD
After 2 weeks of operation
• All PE to MBBR
• Tower offline
• Coagulant Continued
Minimum flow required for filter arms
Slow biological growth on media
Construction 6 months behind
LESSONS FROM CONSTRUCTION
IR zone flap gates
High mixing velocity
Minimize DO entrainment, Media back into IR zone
Flat screen addition
Still - mixing is good!
Keeps media from blocking
Square tanks, air scour facilitate roll
Warranty lengths
Tank 2 end near performance test
21
Phase 2 StartupMarch 2016
Variable MBBR Influent Loading
Construction Impacts - Anaerobic Conditions in Primary Clarifiers
Construction Sequencing, Diurnal Variations - High Ammonia in Dewatering Filtrate
Interim, Partial Process Performance
Limited data to drive decisions
SCADA Trending not online
Nutrient Probes not installed
Only grab and composite samples
Too much construction work was pushed to the end!
LESSONS FROM CONSTRUCTION
Aeration System Safety Factor is Key
Adequate blower pressure / temp capacity
Auto DO control of each zone adds pressure to system
Monitor temp/pressure alarms separately for troubleshooting
Manual Blower Control is tricky
Check DO at several times during the day
Under aeration during day worse than over aeration at night
Motorized Valve Setup Critical
Integrate with process control performance testing
Nitrification Process Performance8/2016-8/2017
Nitrification established,But Lost due extendedaeration system issues Nitrification re-established,
Using Swing Zone, CorrectingMBBR biofilm migration
Nitrifier & Denitrifier Populations and Swing by Season
Pre-Ax Nit-1 Nit-2 Post-AxSwing
Denitrification Process Performance8/2016-8/2017
Nitrification established in Phase 1,Denitrification in Phase 2
Denitrification established, but not optimized untilSCADA, Auto, and Carbon feed and Aeration System fixed
Coagulant feed and CoMag ballasted floc used to polish effluent TSS and TP.
Conclusions & Plan Going Forward(Post-Construction)
Process Differences Reinforced during Construction & Operation
Suspended Growth Process
• Biology can move throughout process train
• 2 mg/L or less DO in liquid phase for aerobic processes
• Suspended biology acts as a buffer
• DO carryover controlled by tapered aeration to match load
Fixed Film Process
• Biology fixed in zones. Adjustments take time.
• 3-4 mg/L DO liquid phase to drive oxygen into film
• Quicker DO changes. DO control more challenging.
• Higher potential for DO carryover to post-anoxic. Additional carbon needed for denitrification.
… and different mixing (RAS, IR) and sludge wasting abilities.
Optimization & Path Forward
Auto DO and carbon control required for optimization.
Blowers being modified to provide better pressure / temperature capability
Swing zone use and number of trains required in winter to be optimized during next couple months. Transition to start early.
Solids recycles will be analyzed to determine ways to spread out ammonia load – Equalization?
Conclusions – Path Forward
Lessons Learned: MBBR Internal Recycle Slipstream
Primary Effluent MBBR Bypass
Accidental during loss of power
No Check Valves – Limited space
Added check on FM
Interlocked Pumps on Fail
