The primary forms of sulfur ...

The primary forms of sulfur in a waste water system are hydrogen sulfide (H2S); elemental sulfur (S); sulfuric/sulfate (SO4-negatively charged); and organic sulfur (RSH).   Sulfur can move back and forth between these forms depending on microbes and redox potential and organic loading and pH.   The hydrogen sulfide species exists as a gas dissolved in water and it can evaporate from the water and condense on other surfaces where oxidation creates sulfuric acid and corrodes the surface.   The quickest way to limit this process is to add and iron salt such as ferrous chloride - FeCl2  (or ferric chloride - FeCl3 - more expensive) at the earliest point in the process.   This will react with hydrogen sulfide gas to form ferric sulfide salt which is insoluble and is not a gas.  This will turn the wastewater (or sludge) very black.  But it works well and works quickly.  That will buy you time while you study the source and form of sulfur and the oxidation  state of the system and perhaps develop a biological control plan using aeration.    Iron salts can be used long term but keep an eye on the pH because these are very strong acids.  Ferrous chloride is less acidic than ferric chloride.