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Thread: Anaerobic or aerobic ?

  1. #1
    Join Date
    Oct 2003
    Living in, not from North Carolina

    Default Anaerobic or aerobic ?

    Just curious, is aerobic (adding of oxygen) a better option for septic tanks ?

  2. #2
    Join Date
    Dec 2003
    Welland Ontario


    Not in my opinion since it requires a pump to be constantly running to oxygenate the tank.

  3. Default


    The aerator websites have glowing reports of how wonderful aerators are for a septic tank. Unfortunately they don't discuss the problems. I have been researching this subject and here is what I found: The aerator I installed stirred up so much sludge in my single chamber tank that a thick, black mud was forced right through my septic effluent filter into my septic field, clogging it up in only a few months. How I rejuvenated my septic field here:

    Reported Aeration Problems
    1) “Aerobic (that need oxygen) bacteria work much faster than anaerobic. As a retrofit a small plastic chamber is often added to the septic tank near the infeed end. The waste enters this chamber and air is pumped in and bubbled through the waste. The plastic chamber has baffles or holes so the waste can leave but it basically creates a small aerobic chamber separated from the main tank. There is some controversy about the use of a separate chamber but most seem to think it is better than just plopping a bubbler into the septic tank. The chamber prevents currents and stirring from happening which can disturb the muck layer on the bottom of the tank. Just dropping in a bubbler will aerate the tank and encourage aerobic bacteria but just like in an aquarium it stirs things up which could cause solids and unprocessed waste to pass out of the tank.”
    Read more: http://www.doityourself.com/forum/we...ml#post1840525
    This is exactly what is happening in my tank !

    3) “Gravity fed septic tank and gravity fed drain field are not designed or recommended for aftermarket aeration systems. Converting gravity fed septic system with an aftermarket aeration system can cause more harm than you are currently experiencing with your gravity fed system. Converting a conventional gravity fed septic system to an aeration system pump can stir up solid waste found in the solid side of the tank forcing undigested sludge into the drain field, making a preexisting bio-mat problem worse further damaging your drain field.” http://www.bio-septic.net/drain-field-restoration/
    (This is exactly what happened in my tank.)

    4) “There are several companies marketing an air pump and diffuser system that will convert the septic tank into an aerobic tank in order to repair the drainfield. These systems typically include an air pump or blower that compresses air and disperses it into the septic tank via a diffuser. The diffuser spreads the air out into the water to provide a good transfer of oxygen and to mix the air into the water. These systems usually include piping to connect the diffuser to the air pump, and possibly a case or cover for the air pump to protect it from the weather.
    “...they have one large drawback. These systems must aerate the septic tank continuously so that the contents of the tank are mixed and oxygen is transferred completely throughout the tank. These processes are called complete mix aeration systems. The problem with these type of systems is that the mixed contents of the tank (we engineers call this the “mixed liquor”) is full of solids and bacterial biomass. In a normal wastewater treatment plant, this mixed liquor is allowed to settle in a separate tank so the biomass and solids sink to the bottom and the clear water is taken off the top. These septic aeration systems don't have a settling process. When water from the house enters the tank, it displaces an equal volume of the mixed liquor out of the tank and to the drainfield. So the drainfield is receiving aerated water, but the water is full of solids and biomass that will again eventually plug the soil pores in the drainfield.” http://www.saberseptic.com/

    Has anyone solved the problem of an aerator stirring up the sludge? I'm testing out a possible solution now, and will be reporting on it. Details here:

    Last edited by Grizz; June 26th, 2013 at 05:08 PM. Reason: bad link

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