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Resiliency and Energy Efficiency in Nitrogen Removal using Membrane Aerated Biofilm Reactor technology
Amit Kaldate, Ph.D., Graham BestSUEZ Water Technologies & Solutions
NYWEA 92nd Annual MeetingNew York, NY04 February, 2020
• Introduction to MABR
• Process Intensification
• Resiliency and Sustainability
• References and Data
• Summary
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Outline
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- Media-supported biofilm with its own built-in oxygen supply
- Counter-diffusional biofilm with “magical” properties1
What is MABR?
1For more information on the unique properties of counter-diffusional biofilms see Downing and Nerenberg (2008) Applied Microbiology and Biotechnology, 81:153–162
Process
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• highest efficiency of oxygen transfer by diffusion of O2 into a biofilm
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Product
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Solving treatment challenges
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o increase treatment capacity
o augment ammonia removal
o implement nitrogen removal
o implement biological phosphorous removal
o high-strength ammonia streams
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process intensificationup to 50% more treatment capacity in existing tank volumes
process resilienceimproved resilience to upset conditions
simple solutioninstalled in existing tanks, no civil works, fast implementation
energy savingsup to 50% less energy than IFAS
an innovative & sustainable solution to augment wastewater plant performance
resilient, simple & sustainable wastewater process intensification
MABR
ZeeLung cassettes are installed in the bioreactor
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• increased biomass inventory in existing volume• enables nutrient removal & capacity expansion
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• Introduction to MABR
• Process Intensification
• Resiliency and Sustainability
• References and Data
• Summary
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Outline
Counter-diffusional biofilm In MABR
o ↑ bacteria inventory = ↑ treatment capacity
o plus… ZeeLung biofilm favors the growth of the bacteria we want – nitrifiers
o the result is even more ↑ treatment capacity
conventional
ZeeLung
reaction occurs at the surface
competition for O2 between heterotrophs & autotrophs
reaction occurs in the biofilm
favors the growth of autotrophs (nitrifiers) at media surface
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Process intensification
Process Intensification = More capacity per tank volume
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a simple solution
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• installed in existing tanks• fast deployment• no impact on hydraulic gradeline
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• Introduction to MABR
• Process Intensification
• Resiliency and Sustainability
• References and Data
• Summary
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Outline
ZeeLung saves energy
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ZeeLungfine bubble aeration
0.5 to 1.51 to 2
≥ 6
surface aeration
aeration efficiencykg-O2/kWh
o transfer O2 without bubbles
o 4X lower energy than bubble aeration
o reduce liquid pumping due to simultaneous nitrification & denitrification
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ZeeLung offers process resilience
attached growth bacteria… not susceptible to washout
rapid response to influent fluctuations
stable cold temperature performance
What is “Resilient” wastewater treatment?
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resilience n.
re· sil· ience | \ ri‐ˈzil‐yən(t)s
2: an ability to recover from or adjust easily to
misfortune or change
‐ What could possibly go wrong?
‐ Are some technologies, equipment or processes more
resilient than others?
* Definition from Merriam‐Webster dictionary (2019)
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What is “Resilient” wastewater treatment?
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Resilient Treatment Systems are:
1. Autonomous ‐ Needs little or no attention. It just works on its own.
2. Dormancy Capabilities ‐ If it is shut down, there are no problems when
it starts up again.
3. Robust/rugged – The process can withstand operating outside the
normal physical conditions expected of the system i.e. the design basis
MABR biofilms provide a unique means for achieving resilience
* Definition from Shaw et al. WEFTEC (2019)
performs well despite sensor or actuator failures
recovers quickly after a shut‐down
can withstand extreme weather events
resists biomass washout during high flow or even flooding events
can run using standby power
runs smoothly when the expert operator is on vacation
runs smoothly when ??????????
4x OTE so blower can be backed up on generator
operation does not require sensors or actuators
low complexity
?
process resilience checklist
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footprint & time constrained upgrade
Yorkville-Bristol Sanitary Districtcustomer challenge
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CAS plant
requires upgrade to treat more load & meet new TP limit
footprint constrained… CAS alternative requires new liquid line
time constrained… new TP limit pending
existing CASspace for new CAS line
Yorkville-Bristol Sanitary District
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3.62 mgd plant near design load
increased organic load from new industries
future regulation for P
existing site is built-out… conventional upgrade requires construction of a new plant
drivers for YBSDdrivers for YBSD
ZeeLung cassettes installed in existing activated sludge tanks
increased biomass inventory can treat more load
free-up volume to enable biological P removal
no increase in energy
ZeeLung solutionZeeLung solution
lowest cost solution to expand capacity… $20m savings
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Yorkville-Bristol Sanitary DistrictZeeLung solution
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footprint & time constrained upgrade
ZeeLung cassettes installed in existing basins
45% increase in capacity
creation of anaerobic zone for bio-P
no net increase in energy
YBSD Overview
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Yorkville-Bristol Sanitary District, Illinois
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ZeeLung cassettes installed in existing tanks
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before after
YBSD performance during wet weather
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“Before” “After”
“During”
• evaluate performance according to oxygen transfer to biofilm before, during and after wet weather event
• how long does it take to recover?
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• very little loss of performance during the wet weather event
• performance drops below average the day following event due to weaker sewage
• performance back to average in four days when sewage strength returns to normal
“Before” “After”
“During”
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• Single cassette
Adelaide demonstration, Ontario
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# Test
1 24‐hour shutdown
2 48‐hour shutdown
3 24‐hour flooding event
shutdowns represent potential:• power outages• blower or equipment
failures• flooding events
Adelaide, ON - extended downtime demonstration
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# Test Description Results
1 24‐hour
shutdown
feed & mixing off for more than 24 h immediate recovery of performance
on startup
2 48‐hour
shutdown
feed & mixing off for more than 48 h recovery of performance within 20
minutes of startup
3 24‐hour
flooding event
feed & mixing off, tank drained and then refilled
with potable water to simulate flooding event
recovery of performance within 10
minutes of startup
“in the timescales used for wastewater treatment (hours and days), this recovery period can be considered
almost immediate”
Adelaide, ON - extended downtime demonstration
For more details, see ‐ Houweling, Kaldate, Peeters, PNCWA, Portland, OR (2019) and‐ Shaw et al, MABR‐ a new choice for resilient wastewater treatment, WEFTEC, Chicago, IL (2019)
Final Effluent Quality
Final Effluent Quality of hybrid MABR/AS system demonstrated through: pilot results modeling
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Operation Data• Pilot system run in the UK for one year
• Nitrification rates remained consistent despite dropping temperature in winter
Temperature Effects
• National Science Foundation funded project to investigate resilience
• includes MABR and MBBR pilots in Houston, TX
• Principle Investigator: Dr. Lauren Stadler, Rice University
• starts early 2020
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MABR Resilience - future work
• resilience is important for wastewater treatment infrastructure
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• Introduction to MABR
• Process Intensification
• Resiliency and Sustainability
• References and Data
• Summary
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Outline
MABR performance indicators
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Oxygen Transfer Efficiency (OTE):
- % of O2 in blower air that is delivered to the biofilm
- OTE 30-40% compared to 10-12% for Fine Bubble
Oxygen Transfer Rate (OTR): - Calculated from OTE and airflow- Typically 8-12 g/m2/d
Nitrification Rate (NR):
- NH4 removed per unit surface area biofilm
- NR = 1.5-3 compared to NR ≈ 0.5 g/m2/d for IFAS
O2 O2
O2
O2 O2
O2
O2O2
O2O2
O2O2
O2
O2 O2
O2O2
O2
O2
O2
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Chicago MWRD demo
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0.5 MGD (2 MLD) demooperated June 2015 – June 2016
0.5 MGD (2 MLD) demooperated June 2015 – June 2016
future P limits… preference to implement biological P removal
construction of new tanks is costly and disruptive
nitrification is challenged under stressed (cold) conditions
commitment to be energy neutral
drivers for Chicago MWRDdrivers for Chicago MWRD
ZeeLung intensifies N removal… potential to enable biological P removal in existing tanks
N removal not impacted by cold temperatures
nitrification rate varies with ammonia load & C:N ratio
30% aeration energy savings with 40% potential
demo resultsdemo results
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Nitrification Rate (NR)
Pilot NR
25th p. 1 to 2
50th p. 1.5 to 2.4
75th p. 1.7 to 2.8
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performance indicatorsexhaust oxygen
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Oxygen Transfer Efficiency (OTE)
Pilot OTE
25th p. 25 to 34%
50th p. 28 to 37%
75th p. 30 to 40%
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Oxygen Transfer Rate (OTR)
Pilot OTR
25th p. 6.8 to 10
50th p. 7.5 to 11.3
75th p. 8.7 to 12
Schilde, Belgium
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16 MLD plant
two parallel processes –activated sludge & MBR
new regulations require 65% TN removal
drivers for Schildedrivers for Schilde
ZeeLung cassettes installed in existing activated sludge “live” tanks
no increase in energy
Reduce capex by avoiding the need to build new tanks
ZeeLung MABR solutionZeeLung MABR solution
increased nutrient removal in existing tanks
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• Introduction to MABR
• Process Intensification
• Resiliency and Sustainability
• References and Data
• Summary
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Outline
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• MABR solves big challenges- footprint, energy, sustainability
• MABR is inherently resilient due to: - fixed nature of the biofilm (resistant to washout)- low energy process easily backed up on standby power
• MABR resilience demonstrated:- wet weather events at YBSD, IL- shutdown events at Adelaide, ON
• MABR provides SND and ammonia-load peak trimming without any reliance on sensors or actuators
Summary - Closing Thoughts
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Amit Kaldate, Ph.D.
E-mail : [email protected]
Tel : 804-756-7790 (O)804-502-8186 (C)
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Thank YOU!
