Hello Daniela, I have some ...

Hello Daniela,

I have some assumptions about your problem: I assume your WWTP is an aerobic process and you may have a sludge digester.

I also assume the digester is under control and is NOT the source of odors. I say this because the gases usually are collected and incinerated or used as bio-gas for heating-steam generation.

To have some guidance into the control of odors we may have insight into the generation of such odorous gases.

Odors in general are mercaptane gases (gases with a double link of Sulfur to alkanes) which generate on anaerobic conditions.
If you were in certain regions of the world where sulfates are very low, most probably you will NOT have this problem. In places where the sulfates are relatively high mercaptanes appear easily and give you odors. This may occur even inside pumping wells. If the sewer has medium strength (or higher strength) and if the sewer system is long this  is even easier.

In the process of generating the odorous gases, there is a step where Sulfur becomes detached from the Sulfate oxygen and chemically active. It is at that time that you can act. I have used Ferric chloride to do so, because the ionic iron is very reactive with the sulfur creating an insoluble compound (an not odorous) named pyrite FeS. This addition has to be followed closely, because Ferric chloride is also a coagulation-flocculation agent.

There are compounds sprayed, masks or either favor oxidation or change the odor, but in general this methods are after the odorous gas is already there.

Bio filters are good but take a large toll on your real state and maintenance, thus I only suggest them after the optimization of the process and measure to correct the generation of odorous gases is tried.

If you need clarification or further assistance contact me at rafael.gaydemontella@gmail.com or call 514 575 5290 (whatsapp)

Rafael