Rethinking vacuum sewers?

  • JKMakowka
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Rethinking vacuum sewers?

First off: hello to everyone here on the SuSanA forums.
I got to know about this forums over at the WASH forums where I am posting quite often.

About me? My name is Krischan and after a some experience in the development sector (mostly drinking-water and emergency context) I am now back at a University research institute in Germany working on various topics related to WASH. Edit: changed jobs since then.

So this brings me to my question ;)
Does anyone have some ideas or feedback to give on the general concept of vacuum sewers in a development context?
I already posted about this in more detail on the WASH forums:

www.watersanitationhygiene.org/forum/php...pic.php?f=370&t=1242

I am well aware that there are various reasons why this technology is probably considered unsuitable at first glance, however I am currently of the opinion that some creative thinking could change that (especially when combined with water-reuse and/or simple bio-gas production).
But any feedback is highly appreciated!

Microbiologist & emergency WASH specialist
WASH news aggregator at: news.watsan.eu
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  • philfei
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Re: Rethinking vacuum sewers?

Dear Krischan,

welcome to the SuSanA Forum and thank you for your introduction. Which is your university and your field of interest?

Regarding your question on vacuum sanitation systems: I know one project with a vacuum system at the Tsinghua University in Beijing, China where the Sino-Italian Environment & Energy Building (SIEEB)has been equipped with a conventional system on one wing and an alternative systems at the other wing of the building. The alternative system includes a vacuum sewer as well as urine diversion toilets. I visited the project in 2009 and it was running quite. At this time there was no reuse of the collected urine, but I am not sure if this is also from your interest.

There is a SuSanA case study on that project where you can find more information: www.susana.org/lang-en/case-studies?view...ypeitem&type=2&id=37

The SuSanA Library shows 7 documents using the search function with "vacuum": www.susana.org/lang-en/library?showby=yeardesc&search=vacuum

Btw I think vacuum systems are an interesting option but due high costs it does not seem to me a good solution for low-income areas.

Cheers,
Philipp

Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
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  • muench
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Re: Rethinking vacuum sewers?

Dear Krischan,

Thanks for your posting. I was going to suggest to you to read the recent report of a vacuum system in the townships of Cape Town, but when I read the discussion you already had on the other forum ( www.watersanitationhygiene.org/forum/php...pic.php?f=370&t=1242 ), I realised that you already had that report (I haven't seen the report yet, only heard about it). I would be skeptical about vacuum systems for slums, I can't imagine that they could possibly be made cheap and robust enough.

But for cities and certain other applications in developing countries (i.e. where people are not totally poor), why not.
Please explain more which application exactly you have in mind?
Which university in Germany are you at?

There is a document called "technology review on vacuum systems" which I have sitting with me here at GIZ in draft form since 2 years. I had sent it to Roediger Vacuum for comment and updating but they had unfortunately no time to do so. That's why we have not published it, but see here, maybe it is useful:

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For developed countries and countries in transition I could well imagine a role for vacuum systems, as you know Roediger Vacuum is the leader in Germany and they have enough projects to keep them very busy... E.g. Vacuum toilets for new stadium in Kiev (if I remember right) and upcoming development in Hamburg-Jenfeld, where it will be coupled with biogas sanitation.

We might have a seminar at GIZ in Eschborn about the SANIRESCH project ( www.saniresch.de/en ) in about November (dates and details yet to be confirmed). There, one of the project partners, which is Roediger Vacuum, might give an overview of vacuum sanitation projects (there was no vacuum toilets in the SANIRESCH project, but Roediger Vacuum had supplied the NoMix toilets).

(If you could be the connector between the two discussion fora, perhaps you could mention there a link to here, so that we all know what is going on in both fora; thanks).
Regards,
Elisabeth

Community manager and chief moderator of this forum
(Funded via GIZ short term consultancy contract)

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  • JKMakowka
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Re: Rethinking vacuum sewers?

For reference:
web.sbe.hw.ac.uk/staffprofiles/bdgsa/tem...UD/PDF/PAP005300.pdf
Is an short report on the problems faced in Cape Town (as I said, mainly higher level management problems and less technical ones).

Thanks for the GTZ paper and the other links!... the GTZ one seems similar but a bit more detailed than the one linked here from 2005.

I am currently working as a PhD level researcher in the Department for Sanitary and Environmental Engineering (DESEE) at the University of Kassel in Germany.
We are not working on vacuum sewer system right now, but rather the application of gravity driven ultrafiltration membranes for emergency use in developing countries.
But due to our experience with decentralized waste-water treatment plants in Germany and sewer systems in general, I am currently proposing to have a closer look at vacuum sewer systems combined with DEWATS in a development context (somehow...).

But as I mentioned in the WASH forums, this is at an brainstorming level only right now, but I see some potential in rethinking the use of vacuum sewerage technology as following:

1. Current systems often include house installations and focus on a completely automatic operation as comparable to "flush and forget" systems found in industrialized countries. While this has obvious advantages from a user point of view, it drives up costs significantly (especially the HH automatic vacuum valves are costly) and is not mandatory for a functioning vacuum based faecal sludge management system (see below).

2. Current system know only one level of service (direct HH connection), while redesigned systems could have different levels depending on HH income and could offer later upgrades between different levels (as well as allowing for tarif cross-subsidy between different level of income). Different levels could go from HH level, to community latrine blocks, to HH but manually operated, to interval vacuum desludging of septic tanks with a flexible hose connected to the system at the nearest road junction and so on. Here is especially the easy expandability and semi-temporal nature of interest for slum settings. Furthermore this adheres to the concept of an early adaptors and progressive upgrade idea much closer than other (often more individualized) sanitation approaches.

3. Combination with DEWATS biogas plant either at the central point where also the vacuum station is (with use of biogas for electricity and vacuum co-generation), and/or at several further decentralized locations with only a vacuum (and maybe biogas) and not a sludge transfer (or liquid only for nutrient reuse?) through a much smaller diameter pipe or flexible hose. Transferred vacuum could be used both to desludge several HH intermediate tanks into decentralized biogas DEWATS plants and also as an easy reactor mixing method to increase bio-gas production.

4. Redesign of vacuum-stations with locally available and off the shelf parts (f.e. motorbike engines or similar; run with bio-gas) and locally producible (and repairable) liquid ring vacuum pumps (proven, extremely simple and nearly maintenance-free design). Cheap electricity co-generation also possible for income generation and community supply. Also a question: is is possible to build vacuum tanks out of ferrocement? Are there other means of re-using equipment for vacuum production (AC compressor pumps, car engine turbo-compressors?)

5. Measures to save water as vacuum severs need much less water, would make it rather interesting for areas with no or only communal tap-stand level water supply. Furthermore vacuum sewer systems can be build pretty flood-safe as vacuum station and waste-water treatment plants can be located at an somewhat elevated position (and pipes are water proof).

6. Creative re-use of existing vacuum pumps (as for sewer systems, pumps have to run only a few hours a day): vacuum pump supported air moisture collection and compression dewing (with higher vacuum levels even distillation at ambient temperatures is possible) for save waste-water reuse and sludge pre-drying (rotary vacuum sludge dewatering is also possible, but probably with higher maintenance needs). Even desalination would be possible, but probably of lesser economic relevance.

7. Creative re-use of existing vacuum pumps: bio-gas upgrading through CO2 and H2S removal with pressurized water stripping (for gas sale and better utilization in engines) & better gas storage through increasing pressure in storage tanks.

8. Minor aspects: Due to suction of air at pit, smell problems of cheaper toilet designs could be nearly eliminated and thus acceptability greatly increased. Besides that, use of an apparent "high-tech" system (but not necessarily so in reality) might make such a system much more attractive (e.g. small tarif "worthy" and thus maintainable) to progress oriented urban inhabitants (something many other "low-cost" solutions lack).

And so on... as I said still at brainstorm level.
Obviously not the absolute cheapest solution, but benefits might justify the investments costs (which can be made lower as proposed above) even for low income countries and potential for progressive cost recovery is high.

Anyways... tell me what you think!

Microbiologist & emergency WASH specialist
WASH news aggregator at: news.watsan.eu
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  • taknev
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Re: Rethinking vacuum sewers?

Dear All,

i have been in the development field for the past 12 years with various UN organizations. For a UNICEF project in Maldives, we have worked with a company called QUAVAC BV ( www.quavac.com ) where the company provided the vacuum sewer system for five islands some five years agao. It was a post tsunami project and the local people were involved in the construction of sewer system as an income generation activity. The system is most suitable for island like situations, flat terrains where you have high water table. The sewer system is in place and working in an excellent conditions and fully maintained by the local islanders themselves till date. They have done not only projects in these situations but also in emergency needs like post war fields, mobile sewers, mobile toilets etc. please contact This email address is being protected from spambots. You need JavaScript enabled to view it. for further details. thanks,
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  • former member
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Re: Rethinking vacuum sewers?

Dear all,

I recently joined the SuSanA Forum as I found very interesting topics and articles here. Especially this topic came to my attention as we are currently working on many projects all over the world in a "development context".

My name is Marc and I work with Roediger Vacuum in the United Arab Emirates since a couple of years, responsible for our activities in the Middle East and South East Asia.

I would be more than happy to contribute in this discussion and general discussions about vacuum sewer systems as we are facing most questions on a daily basis from our clients world wide anyway.

I hope to be able to reply on some points from Krischan during the next couple of days.

Regards,

Marc

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Note by moderators: This post was made by a former user with the login name mlya who is no longer a member of this discussion forum.
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  • JKMakowka
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Re: Rethinking vacuum sewers?

Dear Marc

This was exactly the kind of networking I was hoping for by making this post! You also read the comments over at watersanitationhygiene.org ?

Looking forward to read your remarks.

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  • quarick
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Re: vacuum sewers

Vacuum is generated in the vacuum station and the sewage in the pipeline is sucked into the collecting pit or tank in the vacuum station. The collected sewage is transferred by pumps to a sewage treatment plant. There are two options as for vacuum generation. The one is ejector system and the other vacuum pump. With the ejector system, the sewage in the collecting pit is recalculated by the circulation pumps through the special ejector which generates the vacuum. Read more …….. bit.ly/PXZDQJ
Name: Ricky YD
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  • Agas
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Re: Rethinking vacuum sewers?

Hi Ricky,

Is this something that can be done at a small community level?
We have a community of about 200 people spread in houses over an area of about 5ha.

We are looking for an 'ecosan' solution that is not too far removed from conventional waterborne sanitation, as faecophobia is a major issue, both with those living in the community and various authorities that we need to answer to.

We currently use septic tanks with soak-aways at household level for black water and various mulch basin approaches for grey water.

We are quite concerned about the risk of contamination of the aquifer that provides our water by four boreholes (approx 20m SWL).

thanks,
Agas

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  • fanbin
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Re: Rethinking vacuum sewers?

Dr.Muench adviced me coming here. I also work in this field and posted an report about a practical vacuum system in a Chinese village:
forum.susana.org/forum/categories/98-res...-sciences-china#4952

Bin Fan
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North research center for rural wastewater treatment technology, ministry of housing and urban-rural development of the people’s republic of China ( www.nrcrwtt.ac.cn/ )

Shuangqing Road 18, Haidian District, Beijing 100085
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  • AquaVerde
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Re: Rethinking vacuum sewers?

Re: Low-cost decentralized sanitation system based on vacuum collection and reuse of excreta and kitchen waste (Chinese Academy of Sciences, China) 08 Jul 2013 16:30 #4977

FYI, see a neutral and balanced science report on the issues involved from Canada: www.iwaponline.com/wst/06412/wst064122417.htm ...

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Detlef

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  • ambaya
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Re: Rethinking vacuum sewers?

Dear all,

Thank you for giving me more insight into vacuum toilet technology through your contributions to this forum.

I am desperately looking for existing manufacturers of URINE DIVERSION VACUUM toilets (or vacuum urinal if such thing exists) in the world but especially in China. We would like to request a quote from them. WOSTMAN is not manufacturing vacuum toilets economically at the moment and therefore cannot sell it. EnviroSystems (e.g. Tsinghua Universty's project) has not replied to my query yet.

I am a PhD student at the Hong Kong University of Science and Technology (HKUST) simulating the repayment period of the investment in urine diversion (for urine phosphorus recovery as struvite) for a densely populated city like Hong Kong with its 100s of high-rise buildings. There is a great potential for struvite production from urine in the Hong Kong (HK) context because Hong Kong uses seawater for toilet flushing (SWTF) since 1958, and today SWTF serves 80% of the HK population. Seawater is naturally reach in Mg and therefore external Mg sources are not needed in the recovery of phosphorus (as struvite) in the context of HK. Of courses, the latter implies that:

1) urine is separated from brownwater, at the source, via the use of flush urine diversion toilet; and
2) urine is collected in a large reactor, let's say, in the basement of each building (centralised collection) where phosphorus is allowed to precipitate as struvite, and struvite collected thereof.

The reason I am inquiring about flush URINE DIVERSION VACUUM toilets is to avoid urine scaling (phosphorus precipitation) in vertical pipes that can be as long as 50-100 m (height of HK buildings). If the vacuum can suck up the urine+little flush water as soon as this enters the sewer (at toilet level) maybe that way we can prevent urine scaling in pipes. urine scaling in pipes is often the major source of high operating & maintenance costs.
Of course here I am assuming that the URINE DIVERSION VACUUM toilet vacuums the urine+little flush water but NOT the BROWNWATER.

Thank you,
Bests

Andre

Andre Mbaya
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Current supervisor: Prof G. Chen (Hong Kong)
Former supervisor: Prof G Ekama (South Africa)

Posted by a member of the urine separation group at the Hong Kong University of Science and Technology (HKUST) which values Seawater for toilet flushing (SWTF) as means to recover P from urine, and also for sludge minimisation in conventional BNR. Today, SWTF serves 80 % of the Hong Kong population.
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