Hi Moritz,

The question to "where to draw the line" is always an important one.

And it is very often the case that the line is drawn at the wrong place: Almost all failed water and sanitation projects have their roots in the assumption that O&M just will be done, and later it turned out that it hasn't been done.

In your example a likely scenario could be: You build a solids free simplified sewer system and a constructed wetland for effluent treatment. Septic tanks continue to be without maintenance, thus the effluent will not be solids free. Frequent blockings of the sewers will occur and the constructed wetlands will be colmated after a couple of years.

Of course it is difficult to provide good advice to your situation, but generally speaking I would say that it is better to aim for lower objectives but for a more complete approach. E.g. forget about phosphorous elimination and put a simple but robust treatment plant in place and reserve a good part of the capacity to develop a plan jointly with the local operator for the O&M of your system, including slude management.

Best, Florian

Thanks a lot Florian. I agree, in the case of a simplified sewer I definitely have to stress the desludging of septic tanks.

The topic of phosphorus removal was mostly to get all technologic options on the table, same for nitrification and denitrification, as effluent guidelines for phosphporus and nitrogen are rather high, anyway.

Development has to go step by step. If required an iron-rich sand filter for p-removal can be upgrated at a later stage.

Dear all,

My contract in Raipur came to an end recently. My output was part of a feasibility study of three sanitation concepts proposed by our local partner to the municipality who need to decide with advisory of the local partner and GIZ, and apply for funding at the different national programs (e.g. JNNURM):

• On-site disposal of blackwater trough subsurface infiltration and off-site treatment by a decentralized greywater treatment system.
• Combined discharge of black- and greywater through a low-cost sewerage network and off-site treatment by a decentralized wastewater treatment system.
• Connection to the existing and/or proposed conventional centralised sewer network.

I am thankful to all of you for your contribution. The Susana platform proved to be a very helpful tool for me.

I will try to share my diploma thesis which summarize my findings in the Susana library by the beginning of 2013.

Best regards,

Moritz