What kind of wastewater treatment can be recommended for homes where septic tanks cannot be installed?

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What kind of treatment is to be adopted where a conventional septic tank cannot be provided ? (in case of water logged area, where the houses are very close to water bodies, space constraint problems etc).

Thank you for your suggestions!

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11 Answers

  1. One has to guess why septic tanks can not be adopted. If the local conditions had been described in more detail, an appropriate treatment and disposal method could have been suggested in more clear terms.

    If space on ground is the constraint near the building, it may be possible to find the space away or over the building making use of pumps to transfer the collected sewage.

    If the groundwater table is close to the ground, problem will lie not with the septic tank (which can be made watertight) but the difficulty would be with the soak pit. The alternative to soak pit would be soak trench over a field, hich can be constructed at shallow depth below the ground and it would soak the effluent from the septic tank and treat it through soil to a level that would not contaminate the ground water.

  2. From my experience and MSc studies SBR as package plant in a ground will be good. Because it collect the sewage and SBR treats in one go.  Remember to ensure the diffusers produce fine bubbles. The other advantage of SBR is produce less sludge might reduce certain pathogens. Also you need to remember that existing useful bugs designed to do the treatment has continuous food(sewage) and continuous oxygen. Leaving the house for holiday will reduce food to bugs and impact on their treatment performance.

    regards

    majed murad

    BSc, MSc, CEng, FCIWEM, CEnv.

  3. Dear Mary Rose, Good question.

    He home waste send to sand filter consists of layers of sand and gravel in which the wastewater is treated before it is distributed into the soil. Other types of filters use small foam pieces or peat as a filter medium. With suitable climate and soil conditions, other alternative systems such as evapotranspiration systems, constructed wetlands, spray irrigation, lagoons or mechanically aerated systems for household wastewater treatment are approved in some localities. However, they provide good wastewater treatment on home sites that are otherwise unsuitable for development because the soil type, depth or area is inadequate for an on-site treatment system. The effluent from an aerobic unit can be discharged into a soil absorption system. Holding tanks may be used in temporary situations, such as when you are awaiting a new system hook-up or are at a summer residence.

  5. Dear Mary Rose, your question is quite generic and may have multiple responses.  I will take the assumption that you may have a situation of low cost housing in an area with a shallow water table and little space between buildings.  If you are constrained to having an on-site solution (no possibility of conventional sewers) but compelled to a water flush system as in Asia (vs acceptability of dry sanitation as in Africa), you have limited options.  However it is normally possible to install a septic tank even under these circumstances - or at least to share a septic tank between a few households.  The main challenge will be to prevent the tank floating soon after construction and when it is de-sludged.  This will mean the concrete cover must be designed to provide sufficient gravitational downward force to counteract the upward flotation forces when it is empty.  The tank must also be water-tight.  The next challenge though is to deal with the outflow from the septic tanks as having a high water table minimises the opportunity for sub-surface disposal into infiltration drains. Some solutions include simple filtration of the septic tank effluent through a sand filter and then discharging to a reed-bed wetland area, treating it for re-use as suggested by others, or connecting a number of tanks to a small diameter sewer and draining to a safe disposal place (this will be a solids free sewer and hence can be of a smaller diameter and not necessarily always be at a positive slope (usually 75mm HDPE).  The septic tank may need to be modified for the particular space constraints you are faced with, but it is always beneficial to have an initial anaerobic tank under these circumstances.  

    1 Comment

  6. Hello Mary Rose,

    I recommend looking into Constructed Wetlands for wastewater treatment.

    The US EPA has great guidelines on design and installation of these systems.

    All the best

    Tondre

     

  9. Hi Mary - not sure what your constraint is in terms of the water logged situation, I assume it to be contamination of groundwater by septic tank overflow? 

    I encourage the application of secondary treatment after septic tanks to produce an effluent quality that can be re-used rather than lost to (and potentially polluting) groundwater?

    Septic tanks are great primary waste treatment systems since they do not require much maintenance and attention if configured and sized adequately.

    In any event, and even if the groundwater situation requires putting a treatment system on surface due to the high water table, secondary treatment systems are readily available, compact and can be easy to operate and maintain, a word of warning though, ensure that your engage with a reputable company that has a reputation and track record that is acceptable to the local authorities.

    The treated effluent can be used on the gardens, common areas, recycled for flushing water, community projects, etc

    i enclose a reference to a classic household secondary treatment system receiving septic tank effluent, successfully deployed in South Africa where the effluent is utilised in the gardens.

    Regards and hope this is of assistance, you are welcome to contact me for additional information and support

    Gary

     

     

     

     

  11. might want to check out NSF International web site for on-site waste water treatment options.  Their is an NSF Standard 41 for things like compsost toilets etc.  Here is the NSF web page:  

    http://www.nsf.org/services/by-industry/water-wastewater/onsite-wastewater

    1 Comment

    1. Hi Mary, I have a solution. The Fusion Waste Water Treatment Plant.

      See our website www.maskamwater.com 

      Unit can be buried and anchored and the treated effluent can be used for irrigation, washing cars and other non-potable applications

      Regards,

      Chris.