An In-depth Look at FIL-IDENTPro


In biological wastewater treatment processes, there are twenty-nine commonly observed filamentous bacteria. These bacteria are extremely important to the biological process that occurs in the wastewater treatment plant. They form a backbone for the activated sludge floc which helps the sludge settle in the secondary clarifier. However excessive filamentous bacteria can cause bulking and foaming in the biological process. Research has indicated that various bulking and foaming problems are caused by the type and amount of filamentous bacteria.

Image of various filamentous bacteria.

Correctly identifying these filamentous bacteria in biological wastewater treatment processes is very important for proper diagnosis of a specific bulking or foaming problem. It is the necessary first step in control of bulking and foaming. Different filaments are associated with different operational conditions. For instance, these bacteria can be sulfur oxidizing filaments, low dissolved oxygen filaments, or low food to microorganism ratio (F/M) filaments. Each of these filaments may require entirely different control methods. Correct identification of the filamentous bacteria gives the operator additional knowledge upon which to base his bulking and foaming decisions.

In standard practice, identification or typing of filamentous bacteria is accomplished using a microscope and various staining  techniques. Under the microscope, each filamentous organism is characterized using a number of parameters, including branching, motility, filament shape, filament location, attached growth, sheath, crosswalls, filament diameter, filament length, cell shape and size, presence of sulfur deposits, presence of other granules, gram stain and Neisser stain. Once these characteristics are determined, the filaments are identified by matching the observed filament characteristics with the short descriptions provided in various reference books. Many of the filaments have the same characteristics and, thus, correct identification requires a good deal of experience and time. Even then there is a possibility for error.


Designed from the ground-up as a fast, simple and reliable method of identifying filamentous bacteria, FIL-IDENTPro will no doubt increase the accuracy and decrease the time involved in the typing of filamentous bacteria. Combining the information found in reference materials on bulking and foaming and on filamentous bacteria, and the ease-of-use of a Windows® based program, FIL-IDENTPro is easy to use, intuitive and informative.

Screenshot of a tree in FIL-IDENTPro.

The secret for success? FIL-IDENTPro uses unique search trees that are incorporated into the program structure. These trees rely on accepted filamentous bacteria identification characteristics but further utilize an enhanced algorithm that increases the speed and accuracy of classification. Currently the program has the capability of identifying 23 filamentous bacteria commonly observed in biological systems.

The program has been designed to be user friendly. The screens presented to the user are visual representations of the decision trees in the underlying program code. All option selections are made using mouse clicks on the various options presented on the screens.

FIL-IDENTPro also offers users unique benefits compared to traditional methods of filamentous bacteria identification, including:


Although originally conceived as a program to assist in operator identification of filamentous bacteria, FIL-IDENTPro is invaluable as an instructional tool for use in training personnel in the identification and classification of filamentous bacteria. Graphical representation of the underlying dichotomous search trees enables the student to quickly grasp the methods/steps used in identifying any given filament. Those who can benefit from the use of the program include schools and institutions who routinely provide training in filamentous bacteria classification techniques, as well as industries who conduct in-house training of treatment plant operators. The old adage of “a picture is worth a thousand words” is especially true in identification and classification of filamentous bacteria. FIL-IDENTPro includes many high quality filament pictures which afford the user a means of comparing what they see under the microscope with what the program identifies through the filament characteristics.

Validation / Assurance

The representative images contained in the software provide the technician with a means of comparing what is seen under the microscope with sample images of filamentous bacteria. Oftentimes this can mean the difference between “I think” and “I know.”

Quicker Results

In representative tests of technicians using the program to assist in filamentous bacteria identification, the time required to complete the analysis was reduced by approximately 30% to 40% over that required using the microscope and reference books alone, the conventional methods of identification.


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The Stover Group
P.O. Box 2056
Stillwater, Oklahoma 74076

Phone: (405) 624-0018
Fax: (405) 624-0019

E-mail: [email protected]