What are Filaments


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Filamentous Identification Lab Service. One reason to identify filaments is to determine the filaments characteristics and then determine the type present.  If the type is found out, a root cause can usually be associated with a particular filament.  If the cause is known, then a correction can be made to alleviate problems. Chlorination is only a quick fix.  Without process changes, filaments will grow back after chlorination.

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Training is an integral part of any job. Not everyone is at the same level of training. Many people want beginning concepts and basics. Some need technical information or troubleshooting. Some want equipment, technology or process information.

We have developed a full set of Basic training, Advanced training, Filamentous Identification the Easy Way as well as custom training CD's Manuals. We also provide hands-on training classes and soon will have an Online "E-University".


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At Environmental Leverage® Inc., we have a team of experienced individuals who come into your plant with a fresh pair of eyes.  The system is checked from influent to effluent.  System optimization, equipment efficiency and operational excellence are key components explored. Key Benefits Equipment efficiency Total Cost of Operation reductions Reliability and safety

An onsite audit is conducted to examine system parameters, process controls, and current monitor and control procedures. A physical walk-through is conducted, process flow diagrams are examined, previous design criteria are examined and current standard operating procedures are evaluated along with data logs.




What are Filamentous Bacteria

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Filamentous BacteriaWhat are Filamentous Bacteria and why are they important to my system?


Filamentous Bacteria are a type of bacteria that can be found in a wastewater treatment system.
They function similar to floc forming bacteria in that they degrade BOD quite well. In small amounts, they are quite good to a biomass. They can add stability and a backbone to the floc structure that keeps the floc from breaking up or shearing due to turbulence from pumps, aeration or transfer of the water.
In large amounts they can cause many problems.
Filaments are bacteria and fungi that grow in long thread-like strands or colonies.
I do not have filamentous bacteria at my plant!    Are you sure? Check here.
Filamentous Identification- lab testing inquiries


Filamentous Bacteria have Positive aspects:

They are very good BOD removers
They add a backbone or rigid support network to the floc structure
Helps the floc structure to filter out fine particulate matter that will improve clarifier efficiency.
They help the floc to settle if in small amounts.
They reduce the amount of "pin" floc.

Filamentous Bacteria have Negative aspects:

They can interfere with separation and compaction of activated sludge and cause bulking when predominant.
They can affect the sludge volume index (SVI)
They can cause poor settling if dominant.
They can fill up a clarifier and make it hard to settle, causing TSS carryover
They can increase polymer consumption
They can increase solids production and cause solids handling costs to increase significantly


Bulking settleometer                      after chlorination

Typical SSV30 with Filamentous Bulking  before and after Chlorination


What are some of the Major Causes of Filamentous Bacteria?
• Low Dissolved Oxygenfilamentous bacteria
• Low F/M (High F/M)
• Low Nutrient (N or P)
• Septicity/Sulfides
• Low pH

• Grease and Oil


Filamentous Bacteria- How do I know they are there or how can I monitor them?
Microscopic analyses
Gram stains and Neisser stains should be performed to differentiate certain characteristics of the filaments in order to identify them and determine the cause of them so corrective action can be taken.
• Settleometer - SVI


Filamentous Identification- Why is it used?

Filamentous Identification should be used as a tool to monitor the health of the biomass when a filament problem is suspected. Filamentous Identification is used to determine the type of filaments present so that a cause can be found and corrections can be made to the system to alleviate future problems. All filamentous bacteria usually have a process control variation associated with the type of filament present that can be implemented to change the environment present and select out for floc forming bacteria instead.


Killing the filaments with chlorine or peroxide will temporarily remove the filaments, but technically it is a band-aid. A process change must be made or the filaments will return with time eventually. Find out what filaments are present, find out the cause associated with them and make a process change for a lasting fix to the problems.

Filaments their causes and suggested controls- click on the filament to link to that filament's specific page for more information

Low D.O. Filaments                                                 Control

Type 1701                                                        Adjust the aeration rates or

S. natans                                                          F/M( based on aeration solids)

H. hydrossis                                                     (Long RAS lines or sludge held too long in the clarifier  can sometimes cause the

                                                                        growth of low D.O. filaments even if the aeration basin has sufficient D.O.


Wastes with Limited Nutrients (N or P)                     Control

Thiothrix,                                                        Nutrient addition BOD ratio

Type 021N and N. limicola III                              of 100:5:1 suggested


Low F/M ratios                                                      Control

Type 0041                                                        Increase RAS,

Type 1851                                                        Increase WAS

Type 0803

Type 0675


Sulfide Compounds or Septic Wastes                       Control

Thiothrix,                                                         Pre aeration or pre-

Beggiatoa                                                         chlorination, Check solids holding times, clarifers, digestors

Type 021N, Type 0914                                       EQ tanks, process side holding tanks, dewatering tanks


Low FM and septic conditions

Type 0092, N. limicola II,                                  Same control as septic wastes

Type 0581, Type 0961, Type 0411


Low pH (< 6.5)                                                        Control

Fungal filaments                                                Adjust the pH


High Grease and Oil                                                 Control

Nocardia, M. parvicella and Type 1863                Optimize  Primary clarifier, Bioaugmentation



Some filaments have more than one version of the filament species, with slightly different characteristics for identification.
N. Limicola I
N. Limicola IIfilamentous identification
N. Limicola III
Thiothrix I
Thiothrix II
Photomicrographs of Filaments


Well that is great, but I do not have the abilities to identify filaments in my lab myself, now what do I do?

Environmental Leverage Inc. can help you with a Filamentous Identification Wastewater Biomass Lab Analysis.Environmental Leverage Lab Analysis


Filaments can be internally or externally and they can be free of the floc structures or found intertwined in the floc. Most labs think that filaments need to be extending from the floc in order to be a problem. That is not true. Internal filaments can cause more problems than external filaments. Think of internal filaments causing a structure like a sponge. It will retain water easily and be harder to dewater, will be hard to compress and will take up more space, thereby increasing solids handling costs.


Filaments present in the system do not always have to mean a problem. Some filaments are good if they form a strong backbone and add a rigid network to the floc. They help give the floc more structure and settle faster. Filaments are good BOD degraders also. They are only a problem when they become dominant. If filament abundance is in the abundant or excessive range, having a Filamentous Identification performed is recommended.

When Gram and Neisser stains are performed for filamentous Identification, the types of filaments found present will be noted on the Floc Characterization sheet to the right of the filament section and will be noted on the Cover Sheet. A Filament Causes sheet, Filamentous Predominance sheet and corrective actions will be given and included also with the report. A Filamentous Worksheet will be included. Individual sheets on the actual filaments present in the sample will be included with more information on that particular filament.


Start your way now to a cleaner, brighter effluent with fewer hassles in your waste treatment plant.

Ok, you convinced me. How do I go about sending in a sample?

Contact Jennifer or Laurie at Environmental Leverage- 1-630-906-9791 to set up sampling.


What will I need to send in?

Send in 150 mls of MLSS in a small, plastic bottle with at least 1-2 inches of headspace/airspace in the bottle. This will keep sample from becoming septic in transit and remain fresh for your analysis. Seal the bottle carefully. Send overnight by UPS, Fed ex- etc. If possible, pack with blue ice to keep refrigerated.

1 - Wastewater Biomass Only - $250.00

2 - Wastewater Biomass Analysis as above, plus Filamentous ID - $350.00 Full Filamentous ID Analysis
Both Analysis Includes a CD with Microscopic photographs & digital videos, troubleshooting advice from our expert staff.


India Ink Stain- India Ink is used as a quick and dirty test to tell one of two things.
This is an excellent quick and dirty test that can be used daily. One drop of India ink is added to one drop of the biomass. Everything will be dark except for the polymer generated by the biomass. A normal biomass will have some bright areas relative to the size of the floc structures. Extremely bright or excessive areas will indicate one of two things. A toxic shock to the system or nutrient deficiency. If there are higher life forms present, then a shock can instantly be ruled out and nutrient deficiency can be verified.


India Ink stain India Ink Stain India Ink

Stains, what to use and where to find them

If you are interested in having a Filamentous Identification of your wastewater system performed please fill out the form for sample submission.


How are your bugs doing?
Click on the links below for Filamentous Identification Information


Contact us today and click this link to set up a Filamentous Identification of your MLSS and start saving money at your plant

Wastewater Biomass Lab Analyses with Filamentous Identification

A full set of Stained Filaments - Microscope Slide Set Pre-Made by Environmental Leverage Inc.

microscope slides wastewater

4  © Filamentous ID the Easy Way™ - Training CD - packed full of samples from around the world.

5  All Wastewater Training Materials in printable Pdf form - Click this Link

Hands On Wastewater Training Classes around the country - Earn CEU credits - Courses taught by Tracy Finnegan, Principal Consultant of Environmental Leverage Inc.


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