What are alternatives to bleach in treating filamentous bacteria?
Proliferation of filamentous bacteria can indicate an incomplete denitrification cycle. This is what research at the University of Cape Town showed in the late 1990's.
Do you have ammonia and nitrate readings?
Nature has been resolving this problem for a few million years. You may want to try it. All Bacteria, Fungus, and most of all life are DNA based lifeforms. If you have something that is nasty to get rid of or an organic compound to be neutralized then this requires the RNA microbial group Like all life they do have their parameters to attend to. But since their range is so vast 5.5 to 10.0 it has never been a problem. The end goal is to return the waste back to the soil so the "Soil Food Web" can use the building blocks of life to renew itself.
May not be the solution you were looking for. But it is the correct scientific answer. The field is called Bioremediation. The microbial species is called Archaea.
As a curative, we use Kemira FilamentEx. It will ask you about different operational settings on your SBR and then calculate the corresponding dose. It is very effective and economical for a small plant. But you will need to determine the origin of the filamentous overgrowth. At the same time, once you know the type of filamentous bacteria, you will have to determine the reason for its proliferation.
Sometimes a "shock" treatment with caustic soda works.
Bleach is not at all recommended. First, because it generates a lot of by-products, all very harmful to the aquatic environment, and second because filamentous bacteria are pretty resistant to it. I recommend hydrogen peroxide—much more expensive, but leaves no residue and is very effective. You should look for the causes of a possible nutritional imbalance in your influent or the presence of substrates such as sugars, short-chain fatty acids, etc. that could be contributing to the problem.
I would advise you to carefully investigate the reasons for the appearance and proliferation of filamentous microorganisms (biological foam or overgrowth) and to properly identify them, so you understand what is going on: there are companies that specialize in biomass analysis who will perform lab tests and visit your plant. After this first step, you should think about prevention and not simply resolving the problem at hand, as this is only a short-term solution and can be very costly. In a pinch, add the appropriate type of coagulant (I also recommend Kemira) but especially no chlorine and no caustic soda. If the SBR is continuously overloaded, you could set up an MBBR upstream of the aeration tank and thereby achieve a very stable biological process without the development of filaments.
Are you talking about filamentous bacteria in the sludge or filaments in the effluent?