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

29.4k views

Page selection:
  • Elisabeth
  • Elisabeth's Avatar
    Topic Author
  • Moderator
  • Freelance consultant since 2012 (former roles: program manager at GIZ and SuSanA secretariat, lecturer, process engineer for wastewater treatment plants)
  • Posts: 3372
  • Karma: 54
  • Likes received: 931

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

Dear all,

This has been a very interesting discussion, where once again I learned a lot. Thank you.

What I found interesting is that right from the start, we discovered a discrepancy between the Sandec Compendium definition and the wikipedia page entry.

Sandec Compendium:

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


Wikipedia (en.wikipedia.org/wiki/Septage):

Septage is generally split into three parts in a septic tank:

  • Scum, which floats to the top and is generally where the bacteria live that treat the waste.
  • Effluent, which is the semi-treated liquid that comprises the majority of the material in the septic tank
  • Sludge, the solids which collect at the bottom of the tank

Now it could be a knee-jerk reaction to say "Sandec experts and reviewers know better than Wikipedia authors", but based on the discussion above we found out that there were differing interpretations of the term septage, and in my opinion this needs to be acknowledged rather than just using the adjective "historic".

Therefore, I would recommend for a future edition of the Compendium to say:

Septage: A term that is not clearly defined and which some people mean to denote sludge removed from septic tanks and others to denote the entire content of the septic tank. The authors of the compendium do not recommend use of this term anymore due to this confusion.

Now of course it could be years until there is a new hardcopy of the compendium. And it is inevitable that definitions of terms can slowly change over time. Therefore, I was wondering if the e-compendium would account for that (i.e. be dynamic and have any possible mistakes corrected) or if the e-compendium will remain static and be simply a 1:1 copy of the hardcopy. Based on Dorothee's post above, it seems that the e-Compendium could be deviating or at least giving additional links - unless I misunderstood the post (getting confused between SSWM glossary and e-Compendium glossary or are they identical)?

Another strategy that I would favor is to focus on the wikipedia pages. It must be possible to find people amongst the 4000 members of SuSanA who would spend an hour here or there to edit wikipedia pages? Then I ask myself: why am I not doing it myself? Hmmmm....

I recently read some interesting stuff about Wikipedia for health information. I will put that into a separate post.

Regards,
Elisabeth
Dr. Elisabeth von Muench
Freelance consultant on environmental and climate projects
Located in Ulm, Germany
This email address is being protected from spambots. You need JavaScript enabled to view it.
My Wikipedia user profile: en.wikipedia.org/wiki/User:EMsmile
LinkedIn: www.linkedin.com/in/elisabethvonmuench/

Please Log in to join the conversation.

You need to login to reply
  • Florian
  • Florian's Avatar
  • Water and Sanitation Specialist at Skat Consulting Ltd.
  • Posts: 269
  • Karma: 22
  • Likes received: 131

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

Hi Dorothee,

nice definition, I like it ;)

However, from Linda's last post, it became clear that at Sandec, they prefer not to use the term "septage" and rather use "septic tank sludge", in order to reduce potential for confusion. That explains the word "historic" in the glossary entry for septage. Personally I can live with that.

Most important is that we have a reference glossary for definitions and terminologiy and I'd be happy if the Compendium / e-compendium becomes that reference.

Regards, Florian

The following user(s) like this post: LindaStrande

Please Log in to join the conversation.

You need to login to reply
  • dorothee.spuhler
  • dorothee.spuhler's Avatar
  • Moderator
  • Developing methods and tools to support strategic planning for sustainable sanitation. Particular interested in novel technologies contributing to more inclusive and circular sanitation. Co-Lead of WG1
  • Posts: 311
  • Karma: 14
  • Likes received: 122

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

Dear all

I do agree with Jonathan, Sandec has done a great job and created a set workable definitions in the Compendium.
From the SSWM team, we try to stick to this definitions in order to avoid confusion. Th eCompendium uses the same Database as the SSWM Toolbox and we have recently updated the SSWM terms to make sure they are aligned with the 2nd revised edition of the Compendium:
Septage = A historical term to define sludge removed from septic tanks
(ecompendium.sswm.info/glossary/3#letters and www.sswm.info/glossary/2/letters#term94).

I have now also added the definitions of Faecal Sludge to the database (ecompendium.sswm.info/glossary/3#letterf and www.sswm.info/glossary/2/letterf#term3336 ).

I like the graph from the Compendium used for the explanations of sanitation products: ecompendium.sswm.info/approach-terminology/products



However, these are only the raw products entering the sanitation chain. When you read further in the definition of terms you then will also find additional terms for products such like sludge, dried faeces, pit humus, compost, organics, biogas, etc.
Septage is not part of this product as it is a variation of faecal sludge that in term is a variation of sludge, i.e.:
Sludge= wastewater sludge / faecal sludge
Faecal sludge= sludge coming from on-site sanitation technologies
And Septage= sludge coming from septic tanks and cesspits (but not for instance from pit latrines)
These definitions are useful in practice and help to avoid confusion - even though I assume that there are probably as much different types of sludges as as there are different sanitation technologies.

However, for the sake of clarification, I would suggest to update the current definition from the eCompendium as follows (inspired by the last post of Florian):

Septage = A term to define sludge removed from septic tanks. Septage has some specific characteristics as compared to faecal sludge as it has generally gone through some time of biological degradation and is at least partly stabilized. Feacal sludge defines a wider term and also includes fresher types of sludge from other on-site technologies such as pit latrines.

What do you think?

Cheers,
Dorothee
WG1 Co-lead
Developing methods and tools to support strategic planning for sustainable sanitation. Particular interested in novel technologies contributing to more inclusive and circular sanitation. This email address is being protected from spambots. You need JavaScript enabled to view it.
Attachments:

Please Log in to join the conversation.

You need to login to reply
  • LindaStrande
  • LindaStrande's Avatar
  • Leader of the MEWS group (Management of Excreta, Wastewater, and Sludge) in Sandec (the Department of Sanitation, Water, and Solid Waste for Development) at Eawag (the Swiss Federal Institute of Aquatic Science and Technology)
  • Posts: 26
  • Karma: 7
  • Likes received: 29

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

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
Group Leader MEWS - Management of Excreta, Wastewater, and Sludge
Eawag - Swiss Federal Institute of Aquatic Science & Technology
Sandec - Department of Water & Sanitation in Developing Countries
www.sandec.ch/fsm_tools
www.eawag.ch

Please Log in to join the conversation.

You need to login to reply
  • lucasdengel
  • lucasdengel's Avatar
  • Physician (Dr. med.) by educational qualification, working in public hygiene, environmental health and organic farming for the last >30 years. Running a company called EcoPro, based in Auroville in Tamil Nadu, India - see website.
  • Posts: 24
  • Karma: 2
  • Likes received: 17

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

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
EcoPro
Aurosarjan Complex, Auroshilpam
Auroville - 605101, India
website EcoPro: www.ecopro.in
personal e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
The following user(s) like this post: Florian

Please Log in to join the conversation.

You need to login to reply
  • Florian
  • Florian's Avatar
  • Water and Sanitation Specialist at Skat Consulting Ltd.
  • Posts: 269
  • Karma: 22
  • Likes received: 131

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

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

Please Log in to join the conversation.

You need to login to reply
  • F H Mughal
  • F H Mughal's Avatar
  • Senior Water and Sanitation Engineer
  • Posts: 1026
  • Karma: 20
  • Likes received: 227

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

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

Please Log in to join the conversation.

You need to login to reply
  • lucasdengel
  • lucasdengel's Avatar
  • Physician (Dr. med.) by educational qualification, working in public hygiene, environmental health and organic farming for the last >30 years. Running a company called EcoPro, based in Auroville in Tamil Nadu, India - see website.
  • Posts: 24
  • Karma: 2
  • Likes received: 17

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

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 email address is being protected from spambots. You need JavaScript enabled to view it.
The following user(s) like this post: Elisabeth

Please Log in to join the conversation.

You need to login to reply
  • pkjha
  • pkjha's Avatar
  • Working for over 30 years in the fields of sanitation, biogas from human wastes, septage management, waste water treatment in rural as well as urban areas in India and other developing countries.
  • Posts: 178
  • Karma: 11
  • Likes received: 74

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

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
Web: www.foundation4es.org
Linked: linkedin.com/in/drpkjha

Please Log in to join the conversation.

You need to login to reply
  • Florian
  • Florian's Avatar
  • Water and Sanitation Specialist at Skat Consulting Ltd.
  • Posts: 269
  • Karma: 22
  • Likes received: 131

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

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

Please Log in to join the conversation.

You need to login to reply
  • jonpar
  • jonpar's Avatar
  • As part of the Engineering team, my role at IMC is to lead on the delivery of projects requiring specific expertise on urban sanitation (including excreta/waste/wastewater/stormwater management) focusing on technical, institutional and financial aspects in project design and implementation.
  • Posts: 223
  • Karma: 24
  • Likes received: 87

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

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
Dr. Jonathan Parkinson
Principal Consultant – Water and Sanitation
IMC Worldwide Ltd, Redhill, United Kingdom
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Skype : jonathanparkinson1

Please Log in to join the conversation.

You need to login to reply
  • pkjha
  • pkjha's Avatar
  • Working for over 30 years in the fields of sanitation, biogas from human wastes, septage management, waste water treatment in rural as well as urban areas in India and other developing countries.
  • Posts: 178
  • Karma: 11
  • Likes received: 74

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

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

Please Log in to join the conversation.

You need to login to reply
Page selection:
Share this thread:
Recently active users. Who else has been active?
Time to create page: 0.161 seconds
Powered by Kunena Forum