A presentation on overcoming the hydraulic limitations of the integrated fixed-film activated sludge (IFAS) and moving bed biofilm reactor (MBBR) process. MBBR's are space efficient and allow for nitrification, denitrification, and BOD removal. IFAS can combine the benefits of the MBBR with an activated sludge process, increasing the rate of contaminant degradation.

1. By: Nelson Perez-Jacome
OVERCOMING HYDRAULIC LIMITATIONS OF
THE INTEGRATED FIXED-FILM ACTIVATED
SLUDGE AND MOVING BED BIOFILM
REACTOR PROCESS

2. MOVING BED BIOFILM REACTOR PROCESS
• No suspended growth
• Uses biofilm carriers that allow for the presence of attached growth.
• Space Efficient
• Expandable Capacity
• Flexibility in Reactor Configuration
• Allows for nitrification, denitrification, and BOD removal
• Typically a retrofit solution.

3. Pre-DN AER AER POST-DN RE-AIR WAS
CLARIFIER
MeOH
IMLR
MBBR Process Schematic

4. INTEGRATED FIXED-FILM ACTIVATED SLUDGE
PROCESS
• Fixed-film process
• Combines benefits of an MBBR with an activated sludge process
• Suspended growth and attached growth
• Higher bacterial concentration
• Increases rate of contaminant degradation
• Typically a retrofit solution.

5. WAS
CLARIFIER
PRE-DN AER AER POST-DN RE-AIR
IMLR MeOH
IFAS Process Schematic

6. WHAT ARE BIOFILM CARRIERS?

7. 1985
MBBR
IFAS
1990
Nitrogen and
the North Sea
1st Installation
1995
Lillehammer
WWTP
1ST US Installation
Industrial
2000
70th Municipal
Installation
Water down, ON
Demonstration
2005 2010
1St US
Installation
Municipal
1st US Installation
More than 500
Installations
More than 600
Installations
-15 US
Installations
CHRONOLOGY OF MBBR & IFAS SYSTEMS

8. 1985 1990 1995 2000 2005 2010
Hydraulic
events with
media loss
Broomfield WRF, US
Raisio WWTP, Finland
Groton WWTP, US
Mamaroneck WWTP, US
Hooksett WWTP, US
CHRONOLOGY OF HYDRAULIC FALIURES

9. BROOMFIELD, COLORADO
• Plant is comprised of preliminary, primary, and advanced secondary treatment processes.
• Effluent then undergoes disinfection.
• Advanced Secondary Treatment with an IFAS-based process.
• i.e. free moving biofilm carriers
• Large hydraulic load due to a storm and snow melt event in 2002.
• Pipe in between the bioreactor and the secondary clarifier was undersized.
• Biofilm carriers were discharged to Big Dry Creek.
• Plant was upgraded in 2004 (after upsizing the inadequate pipe). Extra biofilm carriers
were added to the reactor as part of an effort to double plant capacity.

10. RAISIO, FINLAND
• Plant is comprised of preliminary, primary, and advanced secondary treatment processes.
• Advanced Secondary Treatment with an IFAS-based process.
• i.e. free moving biofilm carriers
• Multiple hydraulic failures caused biofilm carrier loss (discharged into Baltic Sea).
• First failure occurred because flat screen walls in the bioreactor were too low.
• Walls were heightened to mitigate loss of biofilm carriers.
• Second failure occurred due to the fouling of the flat retention screen.
• Biofilm carriers were broken by the mechanical mixing process in the anoxic
reactors.
• The flat screens were replaced by cylindrical screen to prevent future faliures.

11. GROTON, CONNECTICUT
• Plant is comprised of preliminary, primary, and advanced secondary treatment processes.
• Effluent then undergoes disinfection
• Advanced Secondary Treatment was upgraded to a IFAS-based process.
• i.e. free moving biofilm carriers
• Various hydraulic failures caused biofilm carrier loss (discharged into the Thames River).
• First failure occurred because cylindrical retention screens caved in.
• A plate was welded to the outside of the screen to provide structural stability.
• Second failure occurred when cylindrical screens were dislodged due to excessive uplift
forces
• Third failure was caused by hydrostatic forces that resulted in the collapse of the
cylindrical screens.
• Likely due to a rapid rise in the water level in part due to screen blinding.

12. GROTON, CONNECTICUT
Cylindrical Retention Screens on Guide Rails

13. HOOKSETT, NEW HAMPSHIRE
• Plant is comprised of preliminary, primary, and advanced secondary treatment processes.
• Effluent then undergoes disinfection
• In March of 2011 there was unpermitted discharge of 250,000 – 300,000 gallons of
inadequately treated wastewater.
• 25% of the biofilm carries at the facility were discharged into the Merrimack River.
• Combination of a heavy rain event and biofilm carriers blocking retention screens to
reduce the hydraulic through-put of the screen.
• Expansive media coverage.

14. HOOKSETT, NEW HAMPSHIRE
Biofilm Carriers on New England Beach

15. MAMARONECK, NEW YORK
• Advanced Secondary Treatment was upgraded to a IFAS-based process.
• i.e. free moving biofilm carriers
• Hydraulic failure occurred during plant start-up.
• Plastic biofilm carriers escaped the reactor and moved into the secondary tank that had
not yet been retrofitted for the IFAS improvement (i.e. no retention screens)
• The biofilm carries flowed through the secondary tank and discharged into the ocean.
• The carries had not yet been used but they had been placed in the sewage
tank.
• Since the failure occurred retention screens have been implemented in the system.
• Expansive media coverage.

16. MAMARONECK, NEW YORK
Carrier Clean Up along Long Island Coast

17. OVERVIEW OF FAILURES
• Flat Retention Screen
• Screen is blocked, minimizing hydraulic throughput
• Cylindrical Retention Screen
• Screen is blocked, minimizing hydraulic throughput
• Structural Failure

18. CONCLUSION
• All hydraulic failures occurred in IFAS systems
• All hydraulic failures occurred during system construction, when controls have been
offline, or in situations where conditions were not within the operating range of the
system.
• Data shows that hydraulic failures can be mitigated through proper design and the
implementation of conservative controls.
• In essence the hydraulic failures can be solved through the use of good engineering
judgement.

19. REFERENCES
• Boltz, Joshua P., William R. Leaf, James P. McQuarrie, Adrienne Menniti, and Glen T.
Daigger. "Overcoming Hydraulic Limitations of the Integrated Fixed-film Activated Sludge
and Moving Bed Biofilm Reactor Process." Florida Water Resources Jounal (January,
2012): 22-32. Print.
• City and County of Broomfield, Colorado. Rep. Black & Veatch Corporation, n.d. Web.
<http://www.nfrwqpa.org/pdf/Approved_Utility_Plans/Broomfield%202011%20Wastewater
%20Utility%20Plan.pdf>.
• Dyson, John. "Nutrient Removal - What Is Available for Municipal Utilities?" WaterWorld.
PennWell Corporation, n.d. Web. 25 Mar. 2013.
<http://www.waterworld.com/articles/print/volume-27/issue-8/departments/wwema-
corner/nutrient-removal-what-is-available-for-municipal-utilities.html>.
• Yeon, H. J., et al. "Comparison of Attached Growth Process with Suspended Growth
Process." 60 (December, 2011): n. pag. WORLD ACADEMY OF SCIENCE,
ENGINEERING AND TECHNOLOGY. Web.
<http://www.waset.org/journals/waset/v60/v60-122.pdf>.