More stringent water quality regulations are making waves across the nation, leaving some municipalities wondering how to keep up with the ever-changing rules. With competing priorities and tight budgets, innovative solutions are needed that can meet permit limits.

In order to regulate the water discharged from municipal wastewater treatment facilities, the National Pollutant Discharge Elimination System (NPDES) permits establish discharge limits and conditions. States continue to update NPDES permits, becoming more and more stringent on the quality of water discharged back into water bodies.

Nitrogen and phosphorus — commonly used in agriculture — are starting to be regulated by the U.S. Environmental Protection Agency (EPA) because of the effect these nutrients have on the aquatic life in streams, rivers and lakes. According to the EPA, too much nitrogen and phosphorus in the water causes a rapid increase in algae, thus harming water quality and food resources, in addition to decreasing the oxygen levels fish and other aquatic life need to survive.

To comply with these new regulations, municipalities are faced with what may be a costly and extensive effort to adjust their wastewater treatment infrastructure. For instance, a conventional activated sludge plant may have to build additional treatment basins upstream of the aeration basin to meet the new nutrient limits. As an alternative to rebuilding or expanding wastewater treatment plants that do not meet the new regulations, some municipalities may benefit from using integrated fixed-film activated sludge (IFAS) technology.

The IFAS solution is a hybrid process that allows activated sludge systems to achieve dramatic gains in productivity without increasing solids levels. IFAS technology supports existing activated sludge plants by increasing capacity and supporting the removal of biological nutrients, such as nitrogen and phosphorus, without additional clarifier or aeration basin volume. The IFAS process uses both suspended and attached growth to increase treatment capacity without adding tank volume.

The IFAS process is usually installed as a retrofit solution for conventional activated sludge systems that are at or beyond capacity. With minimal plant downtime, IFAS upgrades offer a tremendously cost-effective alternative for WWTPs. In addition, it takes full advantage of existing systems, equipment, process knowledge, training and operator skills.

Since the IFAS process is a fairly new technology, and may not be well-known to some, many municipalities may be reluctant to implement it. Other benefits to consider include performance enhancement, future-proof technology, process reliability and intuitive process operation.

While conventional wastewater plant modifications for nutrient removal may have been the obvious choice in the past, new technology, like IFAS, offers an innovative solution to an otherwise expensive and time-consuming task.


See how the IFAS process is being used for the first time in the state of Kansas.

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Caitlin Prim, PE, is a section manager and an environmental engineer at Burns & McDonnell. With a career spanning more than a decade, she has extensive experience delivering successful municipal wastewater and water treatment plant design projects.