Is there a difference between faecal sludge and septage? - The issue of confusing terminology
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TOPIC: Is there a difference between faecal sludge and septage? - The issue of confusing terminology

Is there a difference between faecal sludge and septage? - The issue of confusing terminology 27 Aug 2014 18:34 #9905

  • muench
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Just a small little question from me today:
Is there a difference between the terms "faecal sludge" and "septage"?

I get the feeling that people working in India prefer the term "septage" and people working in Africa rather use "faecal sludge"?

This question occurred to me while reading in this thread started by Pawan Jah about septage management:
forum.susana.org/forum/categories/53-fae...r-septage-management

OK, wait, I think I just answered my own question by checking the Glossary of the Eawag Compendium (www.eawag.ch/forschung/sandec/publikatio...ompendium_e/index_EN) which says:

Septage: A historical term to define sludge removed from
septic tanks.


Faecal sludge appears in their definition of the "product" called "Sludge":

Sludge is a mixture of solids and liquids, containing
mostly Excreta and water, in combination with sand,
grit, metals, trash and/or various chemical compounds.
A distinction can be made between faecal Sludge and
wastewater Sludge. Faecal Sludge comes from onsite
sanitation technologies, i.e., it has not been transported
through a sewer.
It can be raw or partially digested, a
slurry or semisolid, and results from the Collection and
Storage/Treatment of Excreta or Blackwater, with or
without Greywater. For a more detailed characterization
of faecal Sludge refer to Strande et al., 2014 (see Sector
Development Tools, p. 9). Wastewater Sludge (also
referred to as sewage Sludge) is Sludge that originates
from sewer-based wastewater collection and (Semi-)
Centralized Treatment processes.
The Sludge composition will determine the type of treatment
that is required and the end-use possibilities.


Do others agree with these definitions?

Should the term "septage" therefore be "phased out", is that what the Compendium authors suggest if they say "a historical term"?

As a general note, I think this is one of the flaws in our sector that leads to unnecessary confusions time and time again: that we use many different terms to denote - almost - the same thing... Should we try to adopt a common language e.g. by following the terminology proposed in the Eawag Compendium glossary?

It gets even worse when translations to different languages come in, e.g. to French - we discussed in Morocco (GIZ-AGIRE) for ages whether a "puits perdu" or a "puits perdant" is the same as a "pit latrine" or a "leach pit"... (but that's a different topic).

Regards,
Elisabeth
Dr. Elisabeth von Muench
Independent consultant
Frankfurt, Germany
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Last Edit: 27 Aug 2014 18:36 by muench.

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 27 Aug 2014 19:20 #9909

  • JKMakowka
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Yes, I was also a bit confused about it. Certainly septage seems related to septic tanks and would not apply to pit-latrine contents. While I think it would be ok to call the latter also faecal sludge if not totally fresh.

I also came across the definition of septage on the wikipedia:
en.wikipedia.org/wiki/Septage
And there it seems to refer to the entire contents of a septic tank, i.e. also a significant proportion of water, scum etc... not just the settled sludge.
But to my understanding it is most commonly used for the sludge pumped from septic tanks.
Krischan Makowka
Technical Adviser at the Uganda Water and Sanitation NGO Network (UWASNET)
www.uwasnet.org
Last Edit: 27 Aug 2014 19:20 by JKMakowka.

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 28 Aug 2014 09:42 #9913

  • HAPitot
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I would associate 'septage' to cess pools, i.e. those septic tanks that don't discharge into a leach field or a soak pit or something else for disposal. These have to be regularly emptied and the material taken to a facility.

And sludge would be something thickened by deposition, either in a pit latrine, septic tank or a waste water treatment facility. Even though the contents of lined dry pit latrines is usually also called sludge.

H-A
Hanns-Andre Pitot
Technical advisor water and sanitation
presently in Moroto, Uganda

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 29 Aug 2014 08:17 #9924

  • pkjha
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There are two following important publications one each on Septage and Faecal Sludge.

i.A Rapid Assessment of Septage Management in Asia , by EAWAG, USAID, and WATERLINKS, 2010. It defines Septage as the combination of scum, sludge, and liquid that accumulates in septic tanks,

ii.Faecal Sludge Management Systems Approach for Implementation and Operation, by EAWAG and IWA, 2014. It describes Faecal Sludge “comes from onsite sanitation technologies, and has not been transported through a sewer. It is raw or partially digested, a slurry or semisolid, and results from the collection, storage or treatment of combinations of excreta and blackwater, with or without greywater. Examples of onsite technologies include pit latrines, unsewered public ablution blocks, septic tanks, aqua privies, and dry toilets.

There appears to be very thin line between Septage and Faecal Sludge. Septage is limited to septic tank contents where as Faecal Sludge includes contents from other on-site technologies including septic tank.

Pawan
Pawan Jha
Chairman
Foundation for Environment and Sanitation
Mahavir Enclave
New Delhi 110045, India
Web: www.foundation4es.org
Linked: linkedin.com/in/drpkjha
Last Edit: 29 Aug 2014 15:14 by pkjha.

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 29 Aug 2014 13:20 #9927

  • jonpar
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A good point to raise for discussion... and thanks to Elizabeth for raising it because I have often had doubts in my mind about it...

I think there is a "technical" and a "political" dimension to the debate .... From a politician's perspective and probably other non-technical/non-sanitation people I think the preference is probably to use "septage" because "faecal sludge" has an immediate yuk factor associated with it.. but that is just a hunch. I've not done any survey on this.

From a technician's perspective, I agree with Pawan that there is a "thin line" between the two. I agree that septage is what comes out of septic tanks but I don't see why this is a "historical" term. Even if we decided that it was, I envisage that it will continue to be utilised widely (partly because of the political reason described above).

I agree that we need a term that covers everything that comes from on-site sanitation technologies including septic tanks. I think this is fine but when I see desludging trucks pumping septage it often looks more like concentrated wastewater than sludge...

And when I was with IWA, I was involved in a discussion in relation to the definition of "wastewater" for the SDG target. The UN-Water Wastewater task force accepted the "Sick Water" definition of wastewater which includes faecal sludge and septage... I accepted that there is a need for a term that embraces the different residual wastes from sanitation systems, but calling sludge from pits "wastewater" seems to be stretching it too far.

So, it all quite confusing indeed...but well done for SANDEC for putting down set of workable definitions and I think we should as much as possible stick to these compendium definitions.

best regards,

Jonathan
Jonathan Parkinson
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Integrated Sanitation Solutions (i-San) Consulting
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Skype / V-mobile : Jonathanparkinson1
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Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 29 Aug 2014 14:05 #9928

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Hi,
so far I understood in the same way as the quoted definitions and did not find it confusing.

"Historical" probably refers to septic tanks being an quite established technology for a long time and term septage thus used since similarely long time in technical literature, while the attention to sludge from latrines etc. is a rather recent. I find no reason why septage should not continued to be used. Septage has specfic charateristics (e.g. more stabilised and better detwatering characteristics, compared to sludge from latrines) and it is useful to have a special term for this.
Best,
Florian
Florian Klingel
Water and Sanitation Specialist at Skat Consulting Ltd.

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 30 Aug 2014 06:55 #9935

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The Glossary of the book A Rapid Assessment of Septage Management in Asia , by EAWAG, USAID, and WATERLINKS, 2010, mentions:

"Faecal Sludge Management – also known as septage management, FSM concerns the various technologies and mechanisms that can be used to treat and dispose of sludge – the general term for solid matter with highly variable water content produced by septic tanks, latrines, and wastewater treatment plants".
It shows there is very little or no difference in the use of two terminology. In fact book on Faecal Sludge Management describes mainly of septage - contents of septic tanks.

pawan
Pawan Jha
Chairman
Foundation for Environment and Sanitation
Mahavir Enclave
New Delhi 110045, India
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Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 31 Aug 2014 06:45 #9945

  • lucasdengel
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From the quotes, it is clear what the difference is. Septage is the contents of the septic tank (or, maybe only the liquid contents leaving aside the sludge and the scum?); while sludge is the settled solids which are part of the septic tank contents (or septage).
It would be useful and helpful to differentiate these terms, particularly in practice, as services for de-sludging seem to be convinced that they should "empty" a septic tank i.e. take out all septage; while the actual requirement is removal of settled solids - and even this purposefully incompletely so as to leave the microbial populations to continue the job -, so removal of solids to a large extent so as to give the inflowing sewage enough time to separate solids and floating scum from the liquids.
Dr. Lucas Dengel
Executive
EcoPro
Aurosarjan Complex, Auroshilpam
Auroville - 605101, India
website EcoPro: www.ecopro.in
personal e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Last Edit: 31 Aug 2014 06:46 by lucasdengel.
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Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 31 Aug 2014 18:49 #9955

  • F H Mughal
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I tend to agree with Dr. Lucas's views. Septage is the liquid contents (with some portion of solids), typically from septic tanks. Quite often, septage needs further treatment, before safe disposal. If the design of septic tank is such that the wastewater is fully treated in the septic tank, the output is then called effluent, which is disposed off in soakpits (in rural areas). Sludge is that which gets settled in sedimentation tanks. Primary sludge usually needs treatment - anaerobic digesters, or, sun-drying if you have hot day time temperatures. Secondary sludge is pumped to sludge drying beds.

There could be local variations in the terms used. In government schemes here, sewerage is termed drainage. There is a major difference between the two.

Sewage is the term mostly used here in rural areas, while urban areas use the term wastewater. In rural areas here, the excreta from toilets is taken as solid waste!! - mind boggling, isn't it??!!

F H Mughal
F H Mughal (Mr.)
Karachi, Pakistan

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 31 Aug 2014 21:19 #9959

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Hi,
one more definition, from the US EPA Handbook on Septage Treatment and Disposal, 1984: forum.susana.org/media/kunena/attachment...tandDisposal_EPA.pdf

Septage is generally defined as the liquid and solid material pumped from a septic tank or a cesspool during cleaning


This is in line with the definition quoted by Elisabeth in the first post.

The main point to distinguish between septage and fecal sludge probably lies on the word "septic", which implies that the sludge has gone through some time of biological degradation and thus is at least partly stablised. Feacal sludge seems to be used as a a wider term and also includes fresher types of sludge such as from latrines or public toilets.

I'm not sure if I understand the last two posts by FH Mughal and Lucas correctly, but I don't think that only the liquid part in a septic tank should be considered septage. According to the quoted definitions (and my own understanding) septage is both liquid fraction and the solids accumulated on the bottom. The fact that more or less solids often remain in tanks after cleaning makes for part of the variability in septage characteristics.

Again another type of sludge (I think FH Mughal refers to this in part of his post) and not part of what Sandec considers as "Faecal sludge" is sewage sludge, e.i sludge separated in primary and secondary clarifiers in larger facilites for treatment of wastewater/sewage.

But well, I guess the lesson from this discussion is that when talking about sludge, we should always make clear what kind of sludge we are talking about, from wich faciliteies it is colleced.

Best, Florian
Florian Klingel
Water and Sanitation Specialist at Skat Consulting Ltd.
Last Edit: 31 Aug 2014 21:37 by Florian.

Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 02 Sep 2014 06:04 #9975

  • lucasdengel
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My mail was intended to state that septage is all contents of the septic tank, while sludge is only the settled solids. - Rgds, Lucas
Dr. Lucas Dengel
Executive
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Re: Is there a difference between faecal sludge and septage? - The issue of confusing terminology 08 Sep 2014 18:39 #10081

  • LindaStrande
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Within Sandec publications, we purposely avoided the use of the word septage, specifically for these reasons of confusion. Rather we use terms that more precisely describe what is actually being referred to.

Blackwater (the influent to septic tanks) describes the fresh mix of urine, faeces and flushwater, and is transported immediately (i.e. it does not remain as blackwater if it is stored).

Faecal sludge (FS) is a general term which is defined as “comes from onsite sanitation technologies, and has not been transported through a sewer. It is raw or partially digested, a slurry or semisolid, and results from the collection, storage or treatment of combinations of excreta and blackwater, with or without greywater. Examples of onsite technologies include pit latrines, unsewered public ablution blocks, septic tanks, aqua privies, and dry toilets. FSM includes the storage, collection, transport, treatment and safe enduse or disposal of FS. FS is highly variable in consistency, quantity, and concentration."

Septic tank sludge is a specific type of faecal sludge. Other terms we use to talk about septic tanks include scum layer and effluent.

For more information please refer to two of our recent publications, both of which can be downloaded for free:
Faecal Sludge Management: Systems Approach for Implementation and Operation
www.sandec.ch/fsm_book

Compendium of Sanitation Systems and Technologies (2nd Edition)
www.eawag.ch/forschung/sandec/publikatio...ompendium_e/index_EN
Linda Strande, PhD
Senior Scientist
Eawag - Swiss Federal Institute of Aquatic Science & Technology
Sandec - Department of Water & Sanitation in Developing Countries
www.sandec.ch
www.eawag.ch
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