Hello Moritz,

I don't have specific answers to your questions, most of which probably can only really answered by someone knowing the local context well, a few general comments nevertheless.

From what I can read from your description of the situation, I suggest you may rethink the priorities. To put it blunt: Why bother about phosphorous elimination in wastewater treatment in an area where you still have open defecation? This latter problem is certainly the most alarming issue and deserves the highest and most urgent attention.

As you mention, the water body is used for swimming, microbial quality of the effluent may also be a higher risk factor than nutrient load.
In the same sense, I would say the answer to your last question is definitely yes, but more for offering a more hygienic solution to the people for their washing, rather than out of worry for the phosphates entering the pond.

Now if phosphorous and eutrophications is really a problem or not, is not so easy to answer. Urban ponds in tropical areas are generally quite nutrient rich and are a very different ecosystem than European lakes, thus may be much less sensitive to phosphorous immisions. The best bet here is indeed to find out what the local standards are recommending and designing your plant according to these standards, rather than applying stricter standards for nutrient removal than legally needed.

All the best for your project,
Florian

The people from BORDA can probably help you out:
www.borda-net.org/dewats-service-package...wats-the-system.html

Soil retention of phosphorous is (as far as I know) a rather short lived effect in most cases, more promising would be biological integration (artificial wetland etc.) or Mg supplemented struvite precipitation. I have attached an overview on P recovery and reuse innovations and links.

Dear Susana Community,

As monsoon in Raipur is commencing we are about to finish the data collection for the design of a decentralized treatment system.

It was identified that our project area consists of rougly 950 residents, including several small shops and one major temple. Additionally a school with approximately 400 pupils is embedded in the planning area. About 60 % of the residents are discharging 72 cubic meter of domestic wastewater through the drainage system into Bandhwa Talab, which should be protected through the implementation of a decentralized treatment unit. A v-notch was used to estimate four diurnal hydrographs. As 17 % of the residents discharge greywater and blackwater straight into Bandhwa Talab, 9 % into an adjacent pond and 11 % are not connect to the drainage system and the wastewater evaporates and infiltrates, the amount of wastewater will roughly sum up to 100 cubic meter per day.

For the prognosis of future increase of population or change of e.g. mode of water supply we use data evaluated from the household survey conducted in the project area which identified three different modes of water supply: Individual (tap) water supply with storage facilities equals to roughly 130 lcd, common water supply (tap on the street) with roughly 50 lcd and common water supply without storage facility with 15 lcd. Water supply is provided by the municipality for roughly one hour in the morning, and on our in the afternoon.

Open defecation and solid waste disposal were identified as major problems in the project area. It needs to be investigated if a construction of a community toilet, which needs be connected to the decentralized treatment units, should be recommended. The abundance of solid waste could be of major concern for the operation of the treatment unit.

A literature review on different treatment technologies and a feasibility study of the conceptual design taking the local boundary conditions into account (land availability, elevation) will be prepared till end of August and submitted to the local authorities. A detailed project report as basis for the construction of the treatment unit will be designed after funding is secured.

For the conceptual design we would be keen to get input from the Susana Community

• Do you know of a case study/project were a treatment unit was constructed adjacent to an urban water body and discharging into a stagnant water (eutrophication) body which is used for bathing?
• How can such a unit be integrated ecologically into the lake surroundings and be used as a educational interface?
• Which low tech treatment steps (e.g. rock filters, adsorption by different substrates/soils) could be used for the removal of phosphorus to minimize eutrophication effects, how are you experiences?
• Which soils (in India) are best suitable for the adsorption of phosphorus which could subsequently used as fertilizer?
• Which limits of pollutants (BOD, COD etc.), Indian guidelines should be used for the output of the treatment facility to a sensitive waterbody?
• What guidline should be used for the hydrochemical benchmark of such an urban waterbody.
• Could the washing of utensils and clothes, the personal hygiene which involves the use of phosphate containing soaps be moved from the pond to a community washing place?

Please kindly share your experiences/case studies (not only in India) to include previous experiences and lessons learned in the development of an adapted decentalized treatment concept in Raipur.

Thank you very much for you support.

Greetings from Raipur,

Moritz