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Today's environment is placing more and more pressure on wastewater treatment plant owners to control forms of nitrogen in their discharges. The reasons for this pressure range from the threat of acute aquatic toxicity caused by un-ionized ammonia, to the need to control eutrophication and to protect drinking water supplies from nitrate. As a result of the Clean Water Act passed in the early 1970s, many plants in the United States were designed to remove conventional pollutants. Consequently, secondary treatment processes addressed the control of biochemical oxygen demand (BOD5) and total suspended solids (TSS).

As the pressure to upgrade the wastewater treatment facilities to nitrogen control mounts, municipal utilities and industrial waste treaters are faced with the need for substantial capital improvements to implement biological control measures. Consequently, the industry is faced with the questions of:

What processes/technologies are available that can nitrify or nitrify and denitrify?

Which technology is most inexpensive, both to construct and to operate, and how readily can it be incorporated into the current operation?

How reliable are the candidate technologies/processes?

Will nitrogen control present a complicated operating challenge?

Although many options are available, one process is emerging as a viable candidate for upgrading existing plants: the integrated fixed-film activated sludge (IFAS) process. This paper explains what it is, why it is a viable option, describes its development, presents performance information from pilot and full-scale facilities, and presents information on its cost.

Document Type: Research Article


Publication date: 2004-01-01

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