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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 : amit.Kaldate@suez.com

Tel : 804-756-7790 (O)804-502-8186 (C)

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Thank YOU!