Integrated Fixed-Film Activated Sludge (IFAS) Process

The Integrated Fixed-Film Activated Sludge (IFAS) process is typically installed as a retrofit solution for conventional activated sludge systems that are at or beyond capacity.

IFAS upgrades offer an extremely cost-effective retrofit solution to municipal wastewater plant expansion, taking full advantage of existing systems, equipment, process knowledge, training, and operator skills. The technology is compatible with plug flow and complete mix configurations; IFAS hybrid processes are designed for complete compatibility with fine bubble aeration systems, providing demonstrated long-term operational cost savings.

The IFAS variation of the MBBR process gets its name from the integration of biofilm carrier technology within conventional activated sludge. This hybrid process (referred to as an integrated fixed-film activated sludge, or IFAS), enables activated sludge systems to achieve dramatic gains in volumetric productivity without increasing mixed liquor suspended solids (MLSS) levels in the process. By doing so, IFAS systems deliver improved performance while reducing the solids impact on clarification processes. As a result, clarification processes actually benefit from implementing IFAS technology.

Integration of fixed-film technologies and conventional activated sludge is not a ground-breaking approach in of itself. Facilities over the years have implemented caged ropes, cord media, hanging fabric, and other failed methods to increase the density of nitrifying and denitrifying bacteria populations within activated sludge systems.

IFAS technology is the first process specifically designed for ideal operation in municipal wastewater treatment/activated sludge processes. The technology was initially developed by the Government of Canada through 1994-97 where multiple technologies were assessed for cost-effective municipal wastewater treatment upgrades. What resulted in MBBR biofilm carrier technology was determined by Environment Canada to be the definitive solution for IFAS activated sludge upgrades.

The IFAS process self-maintains with the ease of operation found with all MBBR processes. Polyethylene biofilm carriers, optimally designed for high MLSS operation found in typical activated sludge systems, move freely within mixed liquor, providing high-density activated bacteria populations for nitrification, denitrification, and phosphorus removal.

Process Benefits Include:

Cost-Effective, Short Payback Period Investment

IFAS offers a cost-effective means of upgrading municipal wastewater facilities; minimal plant downtime, zero facility construction, and optimization of existing equipment all result in demonstrated cost savings delivered to Headworks BIO customers.

Significant Performance Enhancement

Demonstrated operation and performance data verifies the significant improvements delivered via retrofit of conventional activated sludge processes with MBBR biofilm carrier technology.

Future-Proof Technology

As populations grow, industrial activities increase, or wastewater flows and concentrations change, IFAS technology has the unique capability to be expanded and upgraded to meet new demands. This future-proof capability enables Headworks BIO clients to ensure discharge compliance without significant capital investment or process adjustments in the future.

Enhanced Process Reliability

IFAS achieves increased process stability under conditions of variable mixed liquor, solids retention, and organic loading rates.

Intuitive Process Operation

Operators with experience maintaining conventional activated sludge systems find the operation of integrated fixed-film activated sludge processes highly intuitive. Headworks BIO's Operator Training program covers all aspects of regular maintenance, service, and everyday operation on installation of the new process enhancements.

Reduced Clarifier Loading

By achieving a high-density population of fixed-film bacteria within the activated sludge process, mixed liquor (MLSS) levels are lower in relation to treatment productivity; clarifier performance is optimized by reducing the solids loading generated from the secondary biological process.


More Information

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Biological Processes


Examples of IFAS media

Patent & Patents Pending

AC 450 biocarrier used in IFAS process
AC 450
Protected Surface Area 402 m2/m3

AC 515 biocarrier used in IFAS process
AC 515
Protected Surface Area 485 m2/m3

AC 920 biocarrier used in IFAS process
AC 920
Protected Surface Area 680 m2/m3
Patent Pending


ActiveCell biocarrier shown in mixing process within bioreactor
Media in reactor with biofilm growth
ActiveCell biocarrier shown magnified
ActiveCellTM media under magnification

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