Communal wastewater characteristics and population equivalents in developing countries

  • DennisW
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Communal wastewater characteristics and population equivalents in developing countries

Hi All,

I am assigned to work on a study for BORDA to assess communal wastewater characteristics and population equivalents in developing countries.

Following is a short description of the assignment:

Background
The main design parameters for communal decentralised wastewater treatment plants are the estimated “per capita wastewater production”, the “peak flow factor” and the “per capita organic load”. These parameters are strongly dependent on water availability, climate, culture and income. Literature on per capita wastewater and organic waste production is however mainly available on western countries. Engineers in developing countries are therefore forced to use such design values in the absence of more suitable estimates which may lead to oversized systems and resource wastage.

Goal
The goal of this assignment is to review and collate accessible data on design parameters in developing countries and where possible to classify it depending on country and income group in order to
- identify knowledge gaps which will guide future BORDA R&D efforts
- form the basis for improved DEWATS design procedures

Working steps
- In-depth search and review of literature on the design parameters “per capita wastewater production”, “peak flow factor” and “per capita organic load”
- Tabular collation of all available data
- Identification of knowledge gaps
- Where possible deduce reasonable design parameter values depending on country and income group

Does anyone have valueble data on communal wastewater characteristics in developing countries or maybe useful data sources?


Furthermore, BORDA Africa and particularly I am assigned to work on the revision of Tanzanian wastewater standards. We proposed to revise the effluent standards of a treatment plant according to the population equivalents the facility is designed for. Unfortunately, a definition of population equivalents do not exist for the Tanzanian context. We also discussed that one definition may not even be sufficient, because the regional differences and differences between income groups are suspected to be more significant than for example in the European context.

Does anyone have experience in the definition and formulation of population equivalents (on a national level)?

Any input is greatly appreciated.

Regards,
Dennis

Dennis Wolter
Engineer for BORDA Africa - placed in Zambia
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  • muench
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hi Dennis,

With "communal" do you mean the same as "municipal"? How big would your communities be? If they are a few thousand people (more like cities), then you should look at the literature used for centralised wastewater treatment plants.

We have that here on the forum:
forum.susana.org/component/kunena/165-ce...age-sludge-treatment

How about this freely available textbook by Marcos von Sperling:
“Biological wastewater treatment in warm climate regions”

See here:
forum.susana.org/component/kunena/165-ce...nsq-free-to-download

It probably has information on wastewater characteristics.

Regarding wastewater production there would be a correlation with water consumption. Do you have the data on water consumption for your communities in Tanzania?

And is there anything for you in this "City sanitation planning tool for Dar es Salaam, Tanzania"?
See:
forum.susana.org/component/kunena/194-ci...solutions-go-qwhereq

Let us know how you get on and what you find.

Regards,
Elisabeth

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  • F H Mughal
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Re: Communal wastewater characteristics and population equivalents in developing countries

Dear Dennis,

Municipal wastewater characteristics varies from one place to another. You need to analyse the wastewater in the lab to know its characteristics.

Regards,

F H Mughal

F H Mughal (Mr.)
Karachi, Pakistan
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  • DennisW
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hi Elisabeth, Hi Mughal,

thank you for your responses and excuse my delayed response. I had to have a deeper look into the recommended literature first, before commenting.

Yes, with "communal" I mean municipal. We are mainly focussing on residential areas and set ups, but would also include certain institutions, like schools, hotels, hospitals etc., because we as BORDA also design systems for such institutions.

The book "Biological Wastewater Treatment in warm climate regions" give some really valueble input about the factors and parameters that influence water consumption, wastewater generation, peak flows and pollution loads.

The City Sanitation Guide for Dar es Salaam does not provide in depth information about what I am looking for. I am actually closely working with the colleague who spearheaded the CSP guide for Dar es Salaam on this and other topics.

For the data needed it is not relevant if the data comes from cenetralised or decentralised WWTP, since I am looking at wastewater generation and characteristics, rather than into how it is treated.

The main challenge is that the values to be found in the literature are usually quite general and not really specific.
There we need to strike a balance: Coming up with locally applicable values for the above mentioned parameters (WW generation, Peak flow factors, Pollutant load), but still having values for entire countries or regions and not doing an assessment and lab sampling for every place of interest.

We do not want to know the exact flow and load on a specific date in a specific town, neither do we want a global average, but something in between:
more accurate values to design a WWTP in for example East Africa (or broken down for selected countries if necessary) with appropriate design input parameters.
This assessment is intended to be a desk study and we will not carry out lab testing.
That is why I am looking for literature, where studies on the above mentioned parameters are carried out.
A colleague from BORDA provided me with a PhD thesis looking into these parameters, based on research mainly undertaken in Indonesia, India amd South Africa. I need to find out if I can share the thesis here.

So I am looking for similar research and literature on the above mentioned matters.

Any input is highly appreciated.

Regards,
Dennis

Dennis Wolter
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  • jbachur
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hola Dennis y demás participantes:
Mi nombre es Jorge Bachur y desarrollo actividades en el Ente Regulador de Servicios Sanitarios (ENRESS) de la Provincia de Santa Fe, Argentina ( www.enress.gov.ar ).
Hace unos años atrás realizamos un trabajo de investigación acerca de las características de los efluentes cloacales recolectados en las redes colectoras en servicios centralizados del ámbito geográfico de la provincia de Santa Fe.
Adjunto el trabajo técnico citado.
Espero sea de interés.
Saludos cordiales
Jorge
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  • DennisW
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hola Jorge,

thank you very much for your response. It is a very interesting study, although i had to use google translate to extract the information and hope that information did not get lost in translation.

I am currently finalising the report for this study, in which i collated more than 400 parameter sets from about 70 literature sources (textbooks, research papers, PhD thesis' etc.) with more than 2000 data points (mean, min/max, standard deviation values) on per capita wastewater characteristics (water consumption, wastewater production, pollutant loads (BOD, COD, TSS), nutrient loads (TKN, TP) and peak flow factors.

I also conducted statistical analysis with the data collected to find trends and mathematical correlations between income groups, climate and other key influencing parameters.
It became apparent in this study that there is by far less data available on per capita loads compared to concentrations, furthermore data on water consumption is easier to find than data on wastewater production (which can be easily explained with the simpler means of data collection). Hence, I was able to obtain by far more data on water consumption, than on wastewater production and additionally by far more data on water usage and wastewater production than on per capita.
However, it seems possible to find mathematical correlations between key characteristic parameters and key influencing factors.

Looking at the data you collected: The water consumption seems extremely high (average of 466 L/cap*d for , especially for bigger agglomerations. I assume that this also includes commercial activities? Are industrial wastewaters also included?

Looking at your regression analysis - I am a bit sceptical here, if these can be useful on a broader scale since some parameters seem very context specific (e.g. wastewater parameter depending on the level of satisfaction of basic needs).
However, i will have a closer look at it and try to incorporate the key outcomes in my database.

I furthermore appreciate it to get some data from Argentina, because most of the data I collected is from English reports, hence carried out in Anglophone countries. When benchmarking global characteristic this language barrier is a hindrance, to incorporate values from a broader range of countries.

I would be happy to share my outcomes with you once I finalised it.

Best regards,
Dennis

Dennis Wolter
Engineer for BORDA Africa - placed in Zambia
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  • jbachur
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hola Dennis:
Gracias por haber leído con interés el trabajo enviado.
Los altos valores de consumo de agua (mayores a 400 litros /hab. día) son efectivamente ciertos, debido a un alto porcentaje de agua no contabilizada y falta de micromedición en las localidades de mayor población.
Será un gusto contar con una copia del informe del trabajo que estas desarrollando una vez que lo culmines.
Jorge Bachur
Ente Regulador de Servicios Sanitarios, Rosario, Santa Fe, Argentina
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  • DennisW
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hello Jorge,

thank you for the instant response. OK, in understand now that it is the actual water supply (incl. non-revenue water due to leakages and potential illegal connections)? Then this makes sense, but is not really useful as a design parameter to derive wastewater production per capita from this. But I will have a closer look at your BOD measurements.
I will let you know here in this thread ones my study is finalised.

Best,
Dennis

Dennis Wolter
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  • phreymon
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hi Dennis,

We did quite an intensive study on the topic in the Nile delta in Egypt, which you can find on www.sandec.ch/esriss .

The question was how to estimate the design parameters for small-scale sanitation systems for these villages. We found quite a heterogeneity of wastewater quantities and characteristics from one village to the other. Investigating that, we identified the factors influencing these parameters. Based on the data collected and a material flow analysis, we developed a tool to assess the design parameters, without the need of sampling. Being able to assess without sampling is particularly important, as there is often no sewer network in the initial situation, or no good sampling points. Besides, the wastewater production usually grows when a sewer network is implemented.

You can find all the documents in the "Baseline Data" and "Planning Tool" sections of the webpage.

All the best,

Philippe
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  • DennisW
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Re: Communal wastewater characteristics and population equivalents in developing countries

Hi Philipe,

thank you for your contribution. I am aware of the ESRISS Project. Brilliant work that you did there! I included your results in my study and also used some of your methodologies and still find useful information in the reports, not only about WW characteristics, but also on the policy recommendations.
In my approach, I tried to find correlations on a more global basis, identifying climate and income as main influencing parameters and in the local context differentiating between local income groups, water supply (in house, yard tap, public water point < 200m, public water point > 200m) and sanitation interface (private/shared; full-flush/pour flush).
I furthermore managed to develop a formula to calculate PFF for small-scale systems for private toilets and community sanitation centres, based on literature data.
I am still finalising on the conclusion and some final touches, but I am happy to share the report once done.

Best regards,
Dennis

Dennis Wolter
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