How can we reduce the odor of sewage in the manhole?

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How can we reduce the odor of sewage in the manhole? Let me know the common practices adopted please.

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5 Answers

  1. There is a process that uses advanced oxidation to produce free hydroxyl radicals that will remove sulfide from lift stations. This is used in the USA in several areas. If you are interested in more information about this process, please contact me at rdeal@hubbardhall.com. I will be happy to email you the information.

  2. Other than the already mentioned ideas, here are a few more.

    Introduction of metered bi-oxide to wet wet or waste stream.

    Bleach drip feed will work

    Normal aeration of a wet well has worked in some places I have been

    In another place we put in a smaller pump as a lead. This allowed for longer, and more continual, pump draws that minimized the time that the flow was allowed to be stagnate and septic.

    Have also introduced an additional water flow (small wet-well with low over night flows) to give faster pump cycling. This left little time for the build up of H2S and minimized the order complaints.

     

    Just a few thoughts. I would have to know more about the specifics of the locations, as every one will have its own issues.

  3. I would consider adding a flush mechanism in the lift station. Some pumps can be supplied with a flush valve which flushes the station at every start of the pump, if that's not possible then you can add a separate flush mechanism. Not only does this keep the station clean from sediments and sludge, but it makes any sewage odor disappear.

  4. The biggest odor complaints and health hazards come from the buildup of hydrogen sulfide.  Hydrogen sulfide builds when sewage becomes septic due to anaerobic conditions which can occur from stoppages or slow flowing lines. A properly designed collections system will keep flow regular and moving. Regular preventive maintenance such as treating for tree roots and jetting loose grease deposits will keep the flow moving. The public may complain of odors if the manhole covers do not seal properly. 

    If all of the good practices are being followed, and there is still a problem, there are chemical and biological products that can be fed in to alleviate the problem. We have used ferric chloride to neutralize H2S in a lift station. I recently watched a presentation on an enzymatic odor reducer that worked by breaking down the grease deposits within the system.

  5. For gravity main systems, in my area, Greece - Halkidiki county, keeping the pipes and manholes clean seems to always work, e.g. by performing scheduled washings (1 wash per month or per period of returning odors) with the use of pressurized water. However, this method transfers huge amounts of biological plus inertial solids downstream, so it should be followed by simultaneous solids removal from the system. The same method is advised when odors emitted from house sewage holes. It is old but good and efficient.