Visionery Technology Ltd

Under the Microscope

25 years experience in Microscopic Activity

Microscopic Life forms pdf

Microscopic Filamentous pdf


One of the special aspects of Vistec is the complimentary services we offer with our products. One of the main things we do is Microscopic analysis. We have a wealth of experience in this sector including information about filaments, Protozoa/Metazoa and Flocc structures. A good combination of these 3 aspects of microscopy lead to a healthy sludge. Noticing if one of these aspects has gone wrong can be a simple and effective warning that a problem may be about to occurr. We tend to say that in an ideal activated sludge environment you need the following.


Filaments: it is always good to have just a few filaments, they help with settlement and floc structure, too many and they can cause faoming and problems with dissolved oxygen, eventually killing off all the good bacteria.


Protozoa and Metazoa: We believe it is good to have a healthy mixture of smaller and larger life forms, Rotifers and Paramecium are great and stalkciliates are a good sign of stability.


Flocc Structure: It is essential to have a healthy flocc structure, if they are too dispersed or weak, pin floc can ocur which has a seriously negative effect on settlement.


Filamentous Bacteria

Most filaments have a detrimental effect on WWTP's, they are preferred in small numbers because they can assist with settlement but if you have too many, they can cause all kinds of foaming issues. Filaments are much better at absorbing nutrients than the Protozoa and Metazoa, they can multiply extremely quickly. They can also cause extremely low dissolved oxygen levels which can cause all the desired bacteria to die off. The most common filament is 021N, see left, it is so common it is often tough to understand why it is present, although sometimes it can be down to a large Sulphur content in the sludge. Filament levels can be maintained by running the plant at its optimum levesl, this would involve operating at the best f/m ratio and ensuring other variables such as volatile solids and SSVI are also stable, the use of Micro-nutrients and Augmenting Bacteria will also help prevent filament growth in lagoons and bio-reactors, therefore improving the whole quality of the microscopic environment.


See Filamentous Bacteria Learning Sheet

The Bugs

There are lots of different species in aerobic sludge, below are just a few of them and how they benefit in an activated sludge plant.


See Microscopic Life forms learning sheet


Rotifers are the most desireable microorganism in Activated Sludge, they are large and actually have small teeth so they can crack hard particles which other species can not do



Paramecium are preffered in waste water streams because they are extremely fast. They move quickly so they therefore burn off energy quickly and are soon ready for their next meal.




Stalkciliates (sessile ciliates) are great because if you have them in your plant, it general means the sludge is quite stable and nothing drastic is going to occurr in the short term.




Nematodes and bristleworms are generally visible in older sludge. If you have too many, you may need to Waste/Discard more sludge in order to decrease the sludge age.





  • Improve COD reduction
  • Increase Biogas production
  • Improve Ammonia reduction
  • Help reach discharge consents
  • Hydrogen Sulphide removal
  • Microscopic Analysis experts
  • Reduce filamentous bulking & foaming
  • Odor control

Contact us

07889 168 635

07973 167 730

Environment Agency

Vistec are happy to act as a professional adviser in any contact with local authorities or the Environment Agency. Often at times when communication can be difficult due to breach of consent, having an independent advisor who are experts in effluent treatment can structure conversations and provide comfort for both parties.