What Is IFAS, and How Does It Work?
By: Tom Frankel
Post Date: marzo 31st 2020
Integrated fixed-film activated sludge (IFAS) is a relatively new wastewater treatment technology that offers several advantages over conventional activated sludge technologies. It involves adding an attached growth media to an activated sludge tank to facilitate biomass growth and strengthen the treatment process. The media added may be either fixed or free-floating. The technology is relatively new and can be installed as an upgrade to an existing facility or constructed newly.
Table Of Contents
- How Does IFAS Treatment Work?
- Pros and Cons of IFAS
- Media Types Used for IFAS
- IFAS vs. Conventional Activated Sludge
- Differences Between IFAS and MBBR
- Operation and Maintenance of IFAS System
- Is IFAS Right for Your Application?
How Does IFAS Treatment Work?
The IFAS treatment process combines conventional activated sludge and biofilm technologies in one reactor. IFAS configurations are usually similar to those of standard activated sludge plants and feature biomass carriers in strategically chosen zones of the activated sludge process. This setup results in two different biological populations that act synergistically. The mixed liquor suspended solids (MLSS) degrade the majority of the organic load, and the biofilm establishes a strongly nitrifying population that enables the oxidation of the nitrogenous load. Biofilm processes enable the anaerobic, aerobic and anoxic zones to exist together in one stage, and IFAS systems enable the additional biological population to be on a fixed surface, which means it’s no longer necessary to increase the suspended growth population.
Pros and Cons of IFAS
Some of the advantages of using IFAS include:
- Improved nitrification as compared to simple suspended growth systems due to combining the aerobic, anaerobic and anoxic zones and increasing the sludge retention time
- Faster restoration of system nitrification due to the large mass of nitrifiers on the fixed film
- Increased process stability
- Possible improvements and reduced variation in the Sludge Volume Index (SVI)
- Reduced production of sludge
Some of the disadvantages of using IFAS include:
- High energy requirements, such as for aeration
- High costs for construction and operation
- The need for expert, specialized knowledge
- Challenges in finding mechanical spare parts locally
Media Types Used for IFAS
The media types used for IFAS fall into two main categories: dispersed media that is spread throughout the aeration basin and fixed media that is fixed in place in the aeration basin.
Dispersed media types include:
- Polypropylene finned cylinders
Fixed-in-place media types include:
- PVC structured sheet media
- Fabric web-type media
Dispersed media offers the advantages of exceptional mixing and a high surface area. However, you may experience media loss due to washout or abrasion. In a plant that uses dispersed media, the aeration system may be more difficult to maintain, and the aeration and screens may foul. Dispersed media systems also require additional components, which increases costs.
In addition to being more cost-effective, fixed media systems are easy to install and do not result in material losses. However, they may foul if there is insufficient rag removal, and fabric web-type media is prone to redworm blooms.
IFAS vs. Conventional Activated Sludge
IFAS and conventional activated sludge systems are similar, but some major differences include the combination of aerobic, anaerobic and anoxic zones and the increased sludge retention time in IFAS.
Because fixed film wastewater treatment systems typically require less volume than conventional activated sludge systems, they tend to involve less capital cost. New IFAS systems typically cost less than new conventional activated sludge systems, and adding IFAS technology to existing activated sludge systems can avoid the costs of expanding the system’s capacity.
Differences Between IFAS and MBBR
MBBR stands for moving bed biofilm reactor, a wastewater treatment technique that is similar to IFAS. MBBR involves the use of a reaction tank that contains a plastic-made carrier mixed in water or in a mixture of water and sludge. The main difference between IFAS and MBBR is that the activated sludge that comes from the sludge recirculation is also used in IFAS, which means carrier-fixed biofilms and activated sludge are both used in one reaction tank.
Operation and Maintenance of IFAS Systems
IFAS systems have complex, highly mechanized configurations. Properly operating these systems requires expertise, so a trained professional needs to operate them at all times.
Proper maintenance also requires technical expertise. To prevent ragging and material build-up on the media and retaining screens, primary clarification or fine screening is necessary. If system parts need replacement, they will need to be ordered, as they are not typically available locally. Power system maintenance is also essential, as the system will fail in the event of a power failure.
Is IFAS Right for Your Application?
IFAS technology is suitable for both new constructions and upgrades to existing plants in both municipal and industrial wastewater facilities. Using fixed film aeration technology enables smaller tank sizes, and these tanks need to be designed for the incorporation of dispersed or fixed media. If dispersed media is used, additional auxiliary screens are required.
When used to enhance existing plants, IFAS systems increase treatment capacity without requiring an increase in tank volume. Before installing an IFAS system in an existing plant, assess its aeration capacity to ensure it can handle the increased biochemical oxygen demand (BOD) removal and biomass respiration that results from the enhanced treatment performance that IFAS provides. Media installation also requires careful planning to ensure the basins can properly accommodate the chosen media.
Work With a Professional IFAS Wastewater Treatment Company
SSI Aeration, Inc. can provide IFAS wastewater treatment solutions for both industrial and municipal treatment plants. We can help convert a conventional activated sludge system to an IFAS or MBBR system or provide an IFAS system for a new plant. We also offer a wide range of products as well as design, lab and field services and can use advanced simulation tools to help ensure the success of your installation. Let SSI Aeration’s fully staffed engineering department work with you to help find the ideal solutions for your plant.
With customers in all 50 states and more than 70 countries, the team at SSI Aeration, Inc. has the knowledge and experience to help your wastewater treatment project succeed. Contact SSI Aeration, Inc. online or start a quote today to learn more.
Mr. Frankel co-founded SSI in 1995 with experience in design and distribution of engineered systems. He is in charge of sales, marketing and operations in the company. Mr. Frankel holds multiple US patents related to diffusers. He is a graduate of Washington University in St. Louis.