Hi Joseph,

That slide with data from World Bank in India that you attached is very interesting. It says that 20% of the WWTPs are not operating and 32% are not meeting the BOD standard. That's pretty depressing. The data is from 2013. Any chance that things have improved in the last 5 years?
Also, could you provide the full presentation or the full report from where you took that slide? We should add it to the SuSanA library if it's allowed.

Hi Jonathan,

I think it will be hard to compare the performance of faecal sludge treatment plants (FTSPs) with the performance of WWTPs. I am not aware of broadly accepted performance parameters for FSTPs, e.g. it's not like there would be an effluent BOD concentration or something like that.

What defines if a FSTP is working or not? One parameter could be with regards to drying performance, namely % dry solids in the dried fecal sludge (the higher the better).

Does anyone have information about performance parameters for FSTPs at their fingertips? Oh wait, let me look it up in Kevin's new book:
www.susana.org/en/knowledge-hub/resource...library/details/3439

Found some good information in his Chapter 4:

Page 79:

All septage treatment processes, and most faecal sludge treatment processes, produce a liquid effluent and a sludge residue.
Specific treatment objectives are as follows:

• Reduce the oxygen demand, suspended solids, and nutrient concentrations
in the liquid fraction of the effluent as required to comply with
national environmental regulations.

• Reduce pathogen concentrations in the liquid fraction to levels that
allow safe discharge or reuse.

• Reduce the water content of sludge to the point at which the sludge acts
as a solid, is much reduced in volume, and so is easier and cheaper to
handle and transport.

• Reduce pathogen numbers in sludge to levels that allow its safe end use
or disposal. Treated sludge intended for end use is usually referred to as
a biosolid.

In order to ensure that objectives relating to effluent disposal and reuse and
biosolids reuse are met, both individual countries and international organizations
set effluent and biosolids standards.

Page 82:

Given the relatively small volume of liquid effluent produced by septage treatment
plants, and the difficulty of producing an effluent that meets the WHO
unrestricted irrigation guidelines, a good option for disposal of the liquid
effluent will be to use it locally for irrigation of trees and other crops that
require minimal worker contact.

Regards,
Elisabeth

P.S. Kevin's book is now also cited in the Wikipedia article about Fecal Sludge Treatment:
en.wikipedia.org/wiki/Fecal_sludge_manag...ter_treatment_plants

Many thanks Daniel. I'll check it out. It'll be interesting to see if FS treatment plant performance is any better than typical waste water treatment. best regards, Jonathan

Hi Jonathan,
You may be able to get some information about non-functional WWTPs from Eawag's eFSTP project www.eawag.ch/en/abteilung/sandec/projekte/ewm/efstp/ which is evaluating faecal sludge treatment plants in Africa and Asia or their 4S project www.eawag.ch/en/department/sandec/projec...nitation-scaling-up/ which evaluated small scale systems in India and Nepal.

Regards,
Daniel

Hi Elisabeth

Have attached a slide with details performance evaluation of sewage treatment plants in India.

Hi. thanks. Yes - Elizabeth is right - the question wasn't asking how much wastewater is not treated but how many treatment plants are not functional. I was discussing with a colleague and this question was raised. We didn't define non-functioning but were considering plants in which the level of treatment is so low that it effectively zero. Similarly, we weren't specific about the timescale but I doubt there is a global figure. However, there may be more national studies such as 'Performance evaluation of different wastewater treatment technologies operating in a developing country' Journal of Water, Sanitation and Hygiene for Development (2011) (iwaponline.com/washdev/article-abstract/...irectedFrom=fulltext) and a comprehensive report here publications.iadb.org/bitstream/handle/1...atment-in-Brazil.pdf
best regards, Jonathan

That figure of "90% untreated" is not the same though as Jonathan's question regarding what percentage of built wastewater treatment plants are non-functioning after XX years. That figure also includes wastewater from cities that have sewers but no wastewater treatment plants (WWTPs).

The question back to Jonathan is, after how many years of commissioning? I'd say in their first year they all work - often the first year's operating budget is included in the contract. But once the funder or regulator takes an eye off the plant, it often runs into maintenance issues in those countries where electricity supply might be irregular, corruption might be rife, law enforcement weak etc.

Also what is the definition of "non-functioning"? Some WWTPs might still function hydraulically, i.e. wastewater flows in and out. Perhaps there is some settling of solids, and maybe the bar screens still work... But if they were designed to reach a certain effluent quality and if the regulating authority is weak then I'd say lots and lots of treatment plants in developing countries stop performing very quickly.

One example are plants designed for chemical phosphorus removal: unless the penalities for non-compliance are harsh, there is a real temptation for the operators to turn off or turn down the dosing pump for the alum or ferric chloride to save on operating costs. Result is a higher P concentration in the effluent but "who cares". It's a huge problem. - The same with the temptation to turn down the aerators if it's an activated sludge plant - again to save on power but the result is a lower effluent quality.

Why do you ask, Jonathan? My gut feeling is two thirds don't work but I'd love to hear more from others on this topic.

Regards,
Elisabeth

P.S. LDCs = Least Developed Countries (see: en.wikipedia.org/wiki/Least_Developed_Countries)

Jonathan
I went back to the "original" 2003 source of the statement that 90% of LDC wastewater goes untreated www.un.org/events/water/factsheet.pdf
and this document unfortunately has been removed from un.org

The source document as I recall was not a scientific report so the question requires revisiting.

As I wrote in 2016:
"The point to make here is that the knowledge base for this sector especially when it comes to data on wastewater treatment is far from well established. And much greater efforts are required to provide a clearer view of what the status is of wastewater treatment all around the world. Take a look at the UN database Aquastat dealing with municipal wastewater (and operated by FAO with input from CGIAR-IWMI because reuse of wastewater is so widespread in the world) www.fao.org/nr/water/aquastat/wastewater/index.stm www.iwmi.cgiar.org/2014/06/global-wastewater-database/ "

Regards

Hi Jonathan
We grappled with that question when writing the SEI/UNEP wastewater book a few years ago. www.sei.org/mediamanager/documents/Publi...M&Sustainability.pdf
Page 5 cites two references stating it is about 90% of wastewater from LDCs is released untreated.

I tracked down the original source and the work is described in a SuSanA Forum thread from 2016.
forum.susana.org/various-technology-topi...out-wastewater#18211

Regards

Can anyone send me a link to an authoritative document that quotes the percentage of non-function wastewater treatment plants in LDCs ?
I am sure I have seen a figure quoted but I cannot remember where. I am sure someone out there will be able to help me on this one. best regards, Jonathan