based in Atlanta, GEORGIA (US) (USA)
Force main systems are typically high sulfide odor generators due to septicity conditions related to full pipe flow and a greater anaerobic slime layer (biofilm) thickness. Primary factors that influence sulfide loading generation in a force main include sewage temperature, BOD, retention time, pipe size and flow. Gaseous hydrogen sulfide (H2S) release at the force main discharge is usually the main concern related to odor and corrosion control needs; however, corrosion problems within the pipe can be of a concern (e.g. "crown cutting") at locations where air pockets can lead to concentrated H2S gas build up.
Some basic considerations for assessing an appropriate sulfide odor treatment method for force main systems include:
Retention time / duration of control
Pump station type / cycling (e.g. vfd; start/stop, etc).
Force main injection tap points, if any (e.g. air relief valves)
Existence of intermediate re-lift stations or in series pump stations
Manifold force main systems