Hi,
When land for constructed wetlands or infiltration is not available may be you have to look at a compact aerobic treatment facility, which might achieve the required level of treatment. Alternatively, anaerobic followed by aerobic treatment. In this case of a hospital, may be disinfection would be necessary as a tertiary treatment, if you discharge into surface water.

Regards

Dear Marjin,

Just use other names for the same "vortex": en.wikipedia.org/wiki/Hydrocyclone
"wirbel separator", de.wikipedia.org/wiki/Fliehkraftabscheider and so on. You will find all on the internet, from explanations up to suppliers.

A Swedish example of a small version of vortex for small luxurious (water flush)-sanitation (which do not need extra power) is called Aquatron: www.aquatron.se/how-it-works/separator/

This cyclone-devices can be used for separation, mixing or aeration.

Regards,
Detlef

Dear Jignesh,

Thank you for your post. Are you associated with CSR-Auroville, or with another organization?

I find the Vortex idea quite interesting, so I am trying to find more information about it. So far I have found:

www.cseindia.org/userfiles/Vortex-dewats%20Aug2013.pdf

From that publication it seems that the working principle is intense aeration of the water as a polishing step. Can you confirm that this is true? Or is there another working principle that I am missing here?

In general, does anyone have some more technical/scientific reading materials regarding these vortices?

Regards

Marijn

Hi, with DEWATS instead of wetland or secondary treatment you can use vortex developed by CSR, auroville.
Vortex is very good, we have tried at our site for 1.05 MLD DEWATS.

Kind of comprehensive information on VORTEX:

www.blueeconomy.eu/blog/the-power-of-the-vortex/

Vortexes can clean water, as their rotational speed is higher at the bottom than at the top. In this way, particles are sucked down the vortex and can leave the water by a vacuum created at the end. Furthermore, the water is set into a chaotic state. The constant swirl presses air out of the water and sucks it back in, so that microorganisms are stimulated or die.

This technology is not to be confused with expensive vortexes that dubious websites promote to customers, propagating that they would “harmonize”, “revitalize” or bring back the water to a “virgin state”. On the internet one can read the most bizarre promises about vortexes. These attempts of fraud should however not discourage people to realize the real potential the physical use of vortexes has.

Yes, you can use vortex system instead of PGF and Polishing pond. Contact for vortex system at CSR auroville.

Dear Jan,

I made my self a little Excel, but I am not sure about my theoretical "Milchmädchenrechnung" (simplistic equation), as I am not THE biogas-expert with many years of hands-on field experiences .
I will send you my Excel direct to your e-mail.
Maybe your biogas-colleagues Pedro, Christoph and H-P Mang could comment on it too!?

See Mr. Nils Warburg's very complex EXCEL on " Calculation of Carbon Dioxide Equivalent Emissions of DEWATS in Indonesia " and try it out with your numbers (4,000 p.e. with 800 mg/l COD) too.

CH4 in biogas has a heating value of about 35 MJ/m3. If you are lucky you can produce about 0.12 m3 CH4 / kg COD removed. Treating sewage with a concentration of 1.0 kg COD/m3 you can raise 4.2 MJ/m3 sewage treated. If you can convert this energy in heat- or electrical energy you are lucky.

in short for 0.8 kg COD/m3:
4,000 p.e. (150LPD) with COD 0.8kg/m3 = 480kg/d: (1 kWh = 3.6 MJ)
caloric values: 1,209 kWh/d = 441,504 kWh/a
if 0.07 EURO/kWh = 30,905 EURO/a

Seams to me very valuable, but still I am not "total" sure by my self.
I am interested in commends and advices by colleagues.

All the Best
Detlef

Dear Detlef

Thank you for pointing out all those interesting documents and sharing the numbers here - pretty impressive.

As it was with this particular housing complex project, the owner cared about a wastewater treatment system only at a rather late stage of planning (i.e. construction of the houses already started). I see this happening quite some times. This leaves only little flexibility in the kind of system to implement and the low energy and O&M inputs of DEWATS make them worth while without biogas. But I suppose, the numbers you have given speak for themselves.

Would you have any idea in which range the "actual" caloric values of the biogas production in a case like you mentioned earlier (4000 p.eq. with 800 mg/l COD) for a low-tech biogas plant could be?

Dear Jan,

I am coming back to your and my made messages from 9-10.12.13 on the subject.

Have a look on the work done by Mr. Sharma and Colleagues, which might give you more reliable pre-calculation figures to start with for "your" AD at "gated community", an authorized colony;-)
document no. 2 made Conclusion (page 28) of AD-Analysis:

6. In India, there are many unauthorized colonies where construction of individual septic tanks is not feasible due to lack of space in households. In these cases, a centrally located biogas plant can be constructed connected to each household through internal piping network. This will give access to fresh excreta from houses on continuous basis. As estimated 7000 people would be required for a 200 cu. m biogas plant per day. This requirement can be fulfilled by connecting roughly 1500 households (assuming 4-5 members in each family). ...

see www.susana.org/lang-en/library/library?v...eitem&type=2&id=1938
and
forum.susana.org/forum/categories/53-fae...-analysis-india#7252

Regards,
Detlef

Dear Marijn,

You started this interesting topic back in November 2013. As I have the same interest to find much smaller footprint for CW I started on the ABR too and I got reminded today on your topic.

FYI: Today I got a nice introduction by Dr. Jaime Nivala of UFZ Leipzig, Germany to horizontal- and vertical-CW with very small space requirements. To my surprise with up to x1,000!!! higher degradation rate compered to "normal" CW's. Maybe you heard already about this low-tech technology: "intensive aerated CW", developed by Scott Wallace, USA in 2006. Unfortunately it is patented: "Forced-bed AerationTM"...
- 2011 Germany: naturallywallace.com/docs/103_CE%20News%...tment%20Wetlands.pdf
- wiki.umn.edu/pub/Nieber/EcologicalEngine...wallace_-_part_I.pdf
- naturallywallace.com/tech/
hospital in Haiti naturallywallace.com/projects/projectDetail.aspx?id=17

For the time being just and only my very rough hand written notes I made:
- VAp 0,6 m2/p.e.
- HAp 0,9 m2/p.e.
- Energy demand for intensive aeration 0.16 kWh/m3 (based on a plant with 5,500 m3/d)
- CW-body is nearly full submerged (dammed), which is very different to "normal" vertical CW's
- On the bottom of "normal" designed CW they have several 16 mm PE-pipes like it is used for irrigation purpose. Instate water air is pumped in and through the coarse CW body.
- The horizontal flow version have the advantage of high E-coli removal rate.
- only 10 h/d aeration via PV (photovoltaic system) is possible/enough.

This application is in my opinion very applicable for very densely populated urban areas, as you described the problem in Nepal. In my opinion it is not the right choice for typical rural settings.

If there is interest at this forum I will ask Dr. Jaime Nivala for permission to put public the PDF of her ppt as a new topic.

Maybe you are not surprised if I suggest to have in front of such system an improved septic tank (Biogas-ABR), in my opinion would make this combination a DEWATS with a very small footprint (very compact DEWATS).

Regards,
Detlef

Dear Rohini,
Do you use in Bangalore area anaerobic DEWATS to produce bio-gas too? Please let us know more about your experiences of DEWATS for bio-gas use.
Thanks in advance.
Detlef

Dear BEN.

Greetings from Bangalore! Thank you for your document about Compact DEWATS.
We do also DEWATS Design and implementation both conventional and prefabricated manner. I just wanted to know more details about area, cost requirements for this unit.

Thank you in Advance
Regards
Rohini