Dear Paresh,

Warm greetings!

As promised, here is the link (www.sciencedirect.com/science/article/pii/S1438463922000700) to our recently published manuscript on Pathogen flows associated with Sanitation technologies entitled "Public health performance of sanitation technologies in Tamil Nadu, India: Initial perspectives based on E. coli release" (See the attached copy for details).

Abstract:
Sanitation is intended to reduce the spread and burden of diseases transmitted from excreta. Pathogen reduction from excreta before  sludge  or effluent discharge to the environment would seem a logical and useful performance indicator for sanitation systems. However, the relative magnitudes of pathogen release from common sanitation technologies are not well understood. We, therefore, investigated the  feasibility  of performance measurement of different sanitation technologies in Tamil Nadu, India in reducing the release of the pathogen indicator  Escherichia  coli (E. coli). After conducting users’ surveys and technical assessments of the locally prevalent sanitation systems, we classified them into 7 distinct categories (based on both observed physical characteristics and usage) within a widely-accepted physical typology. Faecal sludge and wastewater samples were collected and analysed for E. coli and total solids from 136 household systems, 24 community systems, and 23 sanitary sewer overflows. We estimated the average volumetric release rates of wastewater and faecal sludge from the different sanitation technologies. Average daily per capita E. coli release was computed and used as one indicator of the public health performance of technologies. We found that on-site installations described by owners as “septic systems” included diverse forms of tanks and pits of uncertain performance. We observed a statistically significant difference in the average daily per capita E. coli release from different sanitation technologies (p = 0.00001). Pathogen release from the studied on-site sanitation technologies varied by as much as 5 orders of magnitude from “lined pits” (5.4 Log10 E. coli per person per day) to “overflowing sanitary sewers” and “direct discharge pipes” (10.3–10.5 Log10 E. coli per person per day). Other technologies lay between these extremes, and their performances in E. coli removal also varied significantly, in both statistical and practical terms. Our results suggest that although faecal  sludge management  along the sanitation service chain is important, sanitation planners of the observed systems (and probably elsewhere) should direct higher priority to proper management of the liquid effluents from these systems to minimize public health hazards. We conclude that (i) the work demonstrates a new and promising approach for estimating the public health performance of differing sanitation technologies, (ii) if E.coli is accepted as an indicator of the public health hazard of releases from sanitation systems, our results strongly suggest that safe  containment  of excreta for an extended period substantially reduces pathogen numbers and the risk of pathogen release into the environment; and (iii) there are some simple but little-used technical improvements to design and construction of on-site sanitation systems which could significantly reduce the release of pathogens to the environment.


Kind Regards, 

Musa

Dear Paresh and Elisabeth, 

The blog post from April 2021 on the UNC website is referring to our work on pathogen releases from sanitation technologies, which is under peer review now. I will be sharing the details as soon as the manuscript is published (hopefully in the next few weeks/months). 


Kind Regards

Musa

(I have moved the last two posts into an existing thread about this project which started in 2015 in order to make the connections)

Paresh, very interesting points you highlighted there. 
You asked about a report. There is this link to the project website in Dan's post: waterinstitute.unc.edu/research/current-projects/unsafe-return/
It provides a link to this report:
Report and Supplementary Materials: Models of Unsafe Return of Excreta in Four Countries
 waterinstitute.unc.edu/wp-content/upload...n-Four-Countries.pdf

The four countries are Senegal, Indonesia, Mozambique and Ghana.
However, that report is from 2019 so I am not sure if the blog post from April 2021 on the UNC website was referring to that one?

I'll reach out to Musa Manga and see if he can clarify.

Regards,
Elisabeth

Dear Dan,
Thankyou for bringing this important piece to the attention of forum members.

From the article on UNC website, it seems leaks in sewers are more hazardous because of concentration as they bring waste from distant sources compared to pits that disperse wastewater in a decentralised manner. This makes perfect sense.

Another finding that may be of interest for members is

Another misperception is that the release of untreated sludge or septage (the solids that settle in a septic tank) is worse than liquid waste. In fact, Manga discovered the potential amount of E. coli. released into the environment due to liquid overflows is about 63 times higher than that associated with sludge.

This questions the focus on FSM (in many parts of the world incl. India) while neglecting effluent from septic tanks.

I couldn't find report/paper that could be referred to. It would be great if you could get the authors to add a link here or post it to the SuSanA library.

Thanks
paresh

Dear Colleagues:

An article on an innovative sanitation research study and the complete article is on the UNC website .  Below is an excerpt:

Early results from a UNC Water Institute study are upending much of what we thought we knew about safe sanitation practices. By Angela Harwood, University Development, Monday, April 19th, 2021.

Musa Manga and a team of researchers from the  UNC Water Institute  have been conducting fieldwork in Tamil Nadu for more than five years for  a study  on the unsafe return of human waste to the environment, a project sponsored by the Bill & Melinda Gates Foundation.

The World Health Organization and UNICEF provide government officials around the world with standardized guidelines, flow models and approaches to safely manage sanitation technologies, but these resources are not always straightforward and may not prioritize safety in public health terms.

The most widely used diagram “tracks ‘safely managed’ versus ‘not safely managed’ sanitation systems by percentage indicators that are unclear, ambiguous and sometimes misleading,” said Manga, whose 15 years of practical experience as a public health engineer informs his research. “My team and I believe we have an improvement on this diagram that may be a lot closer to the truth, and therefore more useful.” 

Manga and his team are tracking a more relevant indicator of potential risk to public health: the number and types of fecal pathogens — bacteria, viruses or other microorganisms that can cause disease — released by different sanitation systems. Their findings are upending much of what we thought we knew about safe sanitation practices.

“Engineers widely regard pit latrines as the least advanced sanitation technology, septic tanks as an intermediate level and sewerage as the most modern and desirable,” said Manga. “We found, however, from a public health perspective, that the reverse is true.

”When sewers overflow — and they overflow frequently for a number of reasons, from clogs to broken pipes to stormwater runoff — they are releasing a higher amount of more active, harmful pathogens into the environment.“ Sewers discharging untreated sewage act as hypodermic needles, injecting the environment with pathogens,” Manga affirmed.

The complete article is on the  UNC website . 

Hi Funke,

Thank you very much for your comment and for pointing out they are the same study. I went back to Cofie et al. 2009 and I see that he cited Kone et al. 2007 in the introduction "In terms of microbial population, pathogen inactivation in the FS/SW co-composting has been reported by Omanhene (2003) and Kone et al. (2007)."

Thank you for bringing this to our attention.

Warm regards,

Ashley

Hi Arno and Joe,

Thank you both for your comments. In terms of what is deemed "safe", this is a difficult thing to define, especially because there are many pathogens present in excreta that presents a risk to human health. We have piloted a survey to ask expert public health microbiologists to try and identify which pathogens are the most important to look at and have attempted to use expert elicitation to develop an estimate of pathogen die-off over time under various circumstances. We have not ironed out the question of "what is safe?" and we admit that even at the end of the project we may not have the most satisfactory answer, but we are trying to move away from simply a mass balance to a "hazard balance".

Our effort focuses at the national level rather than at the local level, and we are hopeful that the SDG 6.2 will encompass "safely managed sanitation" and not settle at simply the improved/unimproved user interface. Rather than only focusing on a binary indicator, our model is intended to reveal the need for safe management along the entire sanitation delivery chain in order to safeguard public health. We see our model as a tool for national policymakers and planners to identify areas along the sanitation delivery chain where excreta is not being safely managed and thereby target resources to improve their services.

Thank you again for your questions,

Ashley

Hi Ashley,

Thank you for the post which provides a good review and lessons. I would be interested in your follow-up studies especially in Ghana where we are located.

You cited Cofie et al (2009) and concluded that "while pathogen concentration was not measured as part of the study, the authors assumed the compost materials were sanitized since internal temperatures were above 45°C and composting occurred over 90 days". Indeed the authors monitored helminth die off as reported in Kone et al (2007) which you also cited on the same page. So it was not an assumption but evidence-based statement.

I would be happy to provide more insight into that project if necessary.
Best wishes.
Funke

The results of the literature review are now available for download at waterinstitute.unc.edu/publication/unsaf...t-literature-review/ and www.susana.org/en/resources/library/details/2304

The review has a wide scope encompassing diverse technologies and all stages of the sanitation delivery chain and was solicited to add to the discussion on global sanitation monitoring and the agenda for the Sustainable Development Goals (SDGs). The Water Institute believes the review has value to the WaSH sector and has made it publicly available for comment in order to incorporate questions and comments from WaSH professionals and practitioners. We encourage you to download the document and provide feedback via e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it..

I also am interested in this 'safety' aspect. It seems to me there is a chronic lack of agreement as to what 'safe' is (as measured by DALYS, QMRA etc) - who is going to make that call and how?

Also my observation from the UN debates on the Sustainable Development Goals is that the moves are away from universal standards and indicators and pressure towards locally defined targets. Of course, these are only preliminary discussions, but the tone seems to be that the mountain of targets and indicators will be impossible to deliver.

So what happens if this system suggests that a country is releasing a high percentage of unsafe faeces into the environment when the local targets (which might be based on the MDG improved sanitation standard) are met?

Without political agreement as to what is 'safe', I can't see that scientific methods of measurement (which in themselves are going to be dependent on good data collection..) are going to lead us anywhere very quickly.

Hi Ashley
What criteria are being used to define safe vs unsafe? How then is hazard defined since exposure is a variable when defining hazard. Any indicator pathogens chosen yet? Using epidemiological data, DALYS, morbidity, mortality, age groups, rural/urban, etc? Will be useful to link this up to the other modelled work at UNC regarding estimates of untreated wastewater/sanitation sources.

Best wishes
--Arno

I would like to introduce to you the details of a new grant that we are working on, with funding by the Bill & Melinda Gates Foundation:

Title of grant: Unsafe Return of Human Excreta to the Environment - Proof of Concept of Estimates for the Unsafe Return of Human Excreta to the Environment

• Name of lead organization: The Water Institute at UNC, Gillings School of Global Public Health, UNC (The University of North Carolina at Chapel Hill)
• Primary contact at lead organization: Pete Kolsky - Co-Principal Investigator; Jamie Bartram- Co-Principal Investigator (or myself for the purposes of this forum)
• Grantee location: Chapel Hill, North Carolina, USA
• Countries where the research will be tested: Netherlands, Uruguay, Egypt, Philippines, Burkina Faso, Ghana, and Fiji
• Start and end date: Feb 2015 to 30 April 2016; Phase 2: 14.10.2016 to 30.09.2018
• Grant type: Global development
• Grant size: USD 267,978 (as per grant database here and Phase 2 here )

Short description of the project:
There is need to track human excreta beyond their initial deposit in toilets through to their final return to the environment, to ensure that the population is properly protected from the diseases spread by this waste.

The work of this project is intended to inform the expected Sustainable Development Goal Target to reduce the amount of human excreta unsafely returned to the environment. The “global scorecard” for excreta management developed will assist governments, funding agencies and development agencies to address progress and the need for improvement more effectively, both from an improved understanding of the situation, and from the clearer insight into the global situation.

Methodology:

• We will model the return of human excreta to the environment through three sanitation technologies: pit latrines, septic tanks, and sewers. Similar to shit-flow diagrams, our model will track human excreta across the entire sanitation chain, including containment, emptying, transport, treatment, disposal/reuse. However, our model will also include both solid (fecal sludge) and liquid (wastewater/effluent) streams.
• Rather than completing a mass balance of waste, as is done in shit-flow diagrams, our model will incorporate pathogen die-off over time and will therefore be representative of a “hazard balance”. The model will also classify the location of the hazard associated with unsafe return at each step in the sanitation delivery chain according to local, community, and the greater environment.
• The tool is currently being developed at the national level, using disaggregated data for urban and rural areas and modeling each setting differently. However, it is anticipated that the model could be used at the regional and local level. The output of the model will assist policy makers by identifying where the greatest hazards are within the sanitation delivery chain and where exposure occurs, at the local, community, or environmental level. Policy-makers could then use tools like Sanipath to further identify specific exposure pathways within the local and community level.

Goals: to develop and pilot approaches for the estimation of the fraction of human excreta unsafely returned to the environment

Objectives:

• to estimate the fraction of human excreta unsafely returned to the environment, and
• to estimate where in the sanitation chain this occurs

Research or implementation partners: University of Alabama, USA

Links, further readings – results to date: waterinstitute.unc.edu/research/current-projects/unsafe-return/ (contains only a short project description so far).

Current state of affairs:
We have developed a preliminary tool and modeled the hazard flow from the unsafe return of human excreta in two countries using available data. The model will be further refined using information from in-country experts and from public health microbiologists.

Biggest successes so far:

• Completion of a strategic literature review examining the unsafe return of human excreta into the environment along the sanitation delivery chain
• Informal elicitation of public microbiologists at the UNC Water Microbiology Conference

Main challenges / frustration:

• Defining “unsafe return” and modeling pathogen die-off
• Lack of available data on household pit latrine and septic tank emptying behavior, method of fecal sludge disposal and treatment, and the level of wastewater treatment (primary, secondary, tertiary) at the national level

If you have any questions or comments, please don't hesitate to raise them in this thread.

Regards,
Ashley


Ashley McKinney

Communications Specialist
The Water Institute at UNC
Gillings School of Global Public Health
The University of North Carolina at Chapel Hill
USA
waterinstitute.unc.edu