How can solar powered sewage treatment plants help municipalities of a developing country ? Does anybody have some case studies or presentation of the said system?

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I saw a  video on this subject, I did not find enough details of the solar power plant and the methodology adopted. This is also crucial since the region where such STPs are proposed, regionally they should be amenable for solar power and its utilisation. Does any one has experience of working on solar powered sewage treatment plant? Can you share your experience and some technical details of the system? Do you think this system will be helpful for developing countries like India?

Thanks. 

Answers

Comments

Engr. Mansoor Ahmed PhD. Scholar
I have gone through the detailed comments from my colleagues. I would like to enlighten some of the real facts pertaining today;

There are two type of Issues at the moment,
1) Selection of the right low Energy Treatment Technology (obviously it must be low cost as well)
2) Selection of the Energy Source

1) Low Energy Treatment Technology
Most of the times in Rural Areas, almost in all countries there is ample land available depending of the cost of the land. Thus Shallow Facultative Ponds, Constructed Wetlands, Trickling Filter Wells (Towers) are some of the almost no energy solutions. Even Decentralized Septic Tanks are one of the promising solution.

But when we come to City Areas, then the land is not available or if available then of unbearable cost. Interestingly the wastewater generation from the urban areas are also much higher than the rural areas. Here come the Energy Consuming Technologies, you talk about MBBR, SBR, EA, EAAS, CMAS, TF, RBC whatsoever in Aerobic System most of the power consumed in Aeration and Pumping.

2) Energy Source
Still Solar Energy proves to be an expensive solution considering the CAPEX and also long run OPEX. One Sq. Meter of PV Cell could produce just only 300 - 600 watts so producing producing 1kW you need a space of 2 Sq. meter. A small plant of capacity 1MGD normally requires 4,000 to 5,000kWhr a Day so one can easily estimate how much space you would require to produce such energy. Space is one aspect.

Now come to Solar Power, normally Solar Power Productive Intensity is considered just 6 - 7 hrs a day in Summer in South East Asia, if you go to Europe then forget about this much intensity duration. And if you talk about Winter, the intensity and angle of sun light also not of much use. This is second aspect.

Now consider the Energy Storage (Battery Backup). This is one of the most expensive part and count for huge OPEX. Wet Batteries have effective life not more than 1 - 2 years and if we come to Dry Batteries, that could go some more but still are much expensive.

For a very small example, I was just trying to have a 400 gallons per day product water Solar Based Tubewell Plus RO for a remote area and the cost with such system came unbearable even sourcing from China.

If some scientist can develop a Very Economical Battery Back Up System; then Solar Panel with inveter could come down to US$ 1 - 2/Watt.

Lets hope for the best to utilize this Divine Free Energy Source economically.
Tina Thompson
that's pretty detailed and good answer.
Shahid Chaudhry
Hi Achar! trust my email will fund you well. Yes, I have had the opportunity to fund a a few partially PV powered STP in California - a practice which started about a decade ago when the PV cost was around $10/watt. Most of these projects were on net metering basis and partially subsidized though public funding. Now that the cost of PV has come down to ~ $4/watt installed (much lower in developing countries), it is attracting more and more water and wastewater utilities. I am aware of at least two dozen such facilities.

A couple of wastewater facilities, in fact, are feeding their surplus generation from PV, anaerobic digesters, small hydro from outfalls, etc.

Another way to reduce aeration load is by using solar powered aerators - a very effective way to enhance biological degradation process especially in oxidation / stabilization ponds. I am aware of few applications where surface aerators were replaced with these equipment. Anyway, I hope this will help you. If you need additional information, please feel free to drop me a line sfc95823@yahoo.com. With very best, Shahid
K.R.T Achar
Hi Shahid Chaudhry,

It is nice to know that solar powered aerators are being used at a few places. Furthermore, as you have rightly pointed out, the cost of PV panels having dropped, more so also in South east Asia as well, usage of solar pv based STPs should indeed become more amenable. Thanks for the information. I shall in future request more information based on your experience and case studies in the future.

Thanks and Regards,
Achar
Shahid Chaudhry
You are welcome anytime, Achar. Drop me an email: sfc95823 at yahoo dot com.
Leonardo Zanata
Hello dear Achar, how you're doing?

In Brazil we use Anaerobic digestors as the low energy treatment option. But you still have to have a aerobic treatment after de anaerobic. Then we use biological filters to the solids separation and aerobic step. In this basic process, if the terrain presents a slope, the only energi that will be requested is to punp the efluent to recicle in the biofilter. If you find low energy request pumps and a good solar system, it may work perfectly.

Regards.
K.R.T Achar
Hi Leonardo Zanata,

Thanks for the information regarding Anaerobic digestors that are used as low energy treatment option in Brazil.

Regards,
Achar
UDAYAKUMAR  KOLLIMATH
Perhaps scores of men are working to solve to problems of the society. May be more details on the said experiment will shed better light.
Meesha Tandon
Hi,
I am not sure about solar STPs but I can tell you about low cost STPs. One example you might have heard of is DEWATS which uses natural filtration processes and plants in the filtration process. Another option is Aerobix which is a stand alone unit that can treat wastewater to drinking water quality standards jusing minimum electricity. DEWATS has been used extensively in India and Aerobix has been used in Jabalpur Madhya Pradesh to treat wastewater from a nallah entering the river.
Regards
Meesha
Ashish  Taneja
Can you please send me details of Aerobix treatment. And How this DEWAT system is better than MBBR???
K.R.T Achar
Hi Meesha Tandon,

Thanks for the information. yes, DEWATS is one of the methodologies used effectively.

Regards,
Achar
Arun Kumar Sivan
Hi Meesha,

Kindly send me more info on the the DEWATS & Aerobix technology you are referring to my e-mail ID iyanengineers@gmail.com
Rashed Alsaed
Hi Neesha, thanks for the short hints re DEWTS and Aeribix system treating domestic sewage at low cost i.e minimal energy demand. My you share your experience regards capital costs on installed systems and OM&R costs as well. If you have any published works re those systems, appreciate receiving e-prints at my gmail account: rashed.alsaed@gmail.com or Birzeit university: rsaed@birzeit.edu. best wishes, Rashed
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