Hello Felipe, I agree with ...

Hello Felipe, I agree with some of the content of the other answers to your question so far, but not all!  First let's keep things simple here.  Sequencing Batch Reactors (SBR) is just another variation of the biological activated sludge treatment process.  True there are many different types of filamentous bacteria, but they are all common in all activated sludge systems.

Identification of the actual type of filament is very important, as it can assist you in determining the source of the filaments.  Eliminating the filaments at the source, so they don't enter your system is always the best method of filament elimination, but may actually be the most difficult.   I agree that there is a good likelihood that your filaments are from an industrial source, that has been my experience as well.  If you can determine the source then depending on the wastewater regulations in your area of Mexico, you may have some authority behind you to force the industry to control the filaments at the source.  That is not always successful however and depends a lot on how large your collection system is and of course how well you know all of your different industrial sources and also the relationship you have established with them.

As for control of filamentous bacteria at your facility, I do not recommend you waste any money on any of the "snake oil" concoctions out there, freeze dried bacteria, or any "special" systems out there!  You will spend a lot of money with questionable results.  Yes, process control adjustments to your system are critical, so that you eliminate or minimize the conditions that are allow the filaments to thrive.  However, no two SBR systems are the same.  So I would never recommend specific process control adjustments based on my experience with my system.  Use the ranges established in all the manuals, only adjust one parameter at a time, and waaaiiittt long enough to see a change before making another adjustment or parameter change.   Every treatment system has a "sweet spot" and your main job is to find it! 

True, too high of a DO concentration can increase filament growth, but not all treatment systems will allow for large decreases or fluctuations in DO.  The quality and turbidity of your effluent may suffer and you could find yourself exceeding your discharge limitations very quickly, so be very cautious.  Again, very small adjustments over time.  Go at least one full MCRT or SRT cycle (two if possible) between adjustments.  Patience, my friend, patience!

Chlorine is the most common and most successful method of controlling (killing) filaments growing out of control in your system.  Again you must be very careful using chlorine.  In order to not kill too many of your viable organisms, you need to start with a small dosage and gradually increase the dosage (don't forget the 1 or 2 MSRT/SRT cycle rule!)  Also remember, that as you kill the filamentous organisms they will appear in your effluent and show as increased turbidity, so you don't want to kill them all off at once!  The starting dosage is critical (so many lbs of chlorine for every 1000 mg/l MLSS), but I will not quote it now, because I am not 100% positive that I remember it correctly, without referring to the "bible"!   What is of the second highest importance is the application point.  For chlorination to be affective you must have good mixing.  An excellent point of injection is directly into a Return Activated Sludge(RAS) pipeline, and make sure that is has enough time in the pipe to mix thoroughly.  Don't just try to drip the chlorine into your activated sludge tank or RAS channel! 

The regional expert on filamentous bulking and control, at least in California and arguable in the entire United States is Dr. David Jenkins, out of Berkley, CA.  Dr. Jenkins has written several books and papers on the subject.  He co-authored a book with Michael G Richard and Glen T Daigger, which in my 36 years of experience and universally agreed upon, is the "authority" on the subject.  "Manual on the Causes and Control of Activated Sludge Bulking, Foaming, and other Solids Separation Problems", publication date 2003/8/27, Publisher Crc Press.

I hope this was helpful, good luck and take care,

Mark B. Gingras                                                                                                                                                   "The Ribeye Guy"

Wastewater/Water Recycling Operations Manager                                                                         Presently Retired