Decentralized Sewage ...

Decentralized Sewage Collection and Treatment

Hi Qasem;

As part 2 to my answer earlier; I would suggest that you first treat Kabul in the same manner we look at managing water networks; - ie: first break it up into smaller and easier to manage Sewage zones based on local features such as topography and quantum of water supply.

This will allow you to figure out what parts can be decentralized and what cannot not. The idea of many small mini-STP's does not work as we still have to transport the solid component of the sewage to them which is difficult when water supply is low and variable as I previously mentioned. The best solution I have encountered in 15 years off working is the one I currently represent as it digests the organic load and traps the inorganic in multiple biodigester tanks. As a result you have smaller quantities of inorganics distributed in each tank instead of large amounts accumalating at a single location and choking the network. Eliminating the requirement of transporting solids means that the network can have shallower slopes and will be easier to install. This also eliminates the need for manholes. the piping can now be HDPE or even PVC-O whose flexibility allows you to navigate obstructions and corners in Asia's organically grown cities...

Hope this helps, I think it is the only solution that at one go eliminates the problems you mentioned as both the greywater and sewage are dealt with. best of luck and please feel free to reach out to me via email at sdeshpande@clearford.com for any further help...