You should rethink your ...
Published by Gerd Teunissen, technical director at INTERAGUA, Lda.
You should rethink your options: instead of masking bad odors, you should try to prevent them.
A well designed, dimensioned, constructed and operated (!) WWTP or STEP does NOT produce bad smells. The only place you may find these are at the excess sludge treatment, where air circulation over a small activated carbon filter can do the job.
In an over-dimensioned pump pit the wastewater stays too long and goes septic.
If you have a header tank, recirculate a generous part of you MLSS and mix well. This prevents bad odors, fights bulking sludge and provokes (at least partial) de-nitrification.
Make sure your aerated tank is well mixed to avoid anaerobic pockets.
Another place where you can have odors is the final clarifier, if settled sludge is not removed completely, stays in pockets at the bottom and goes septic. Then starts to float as black, H2S rich sludge.