2.2 Sanitation Products

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En provenance du cours de École Polytechnique Fédérale de Lausanne

Planning & Design of Sanitation Systems and Technologies

450 notes

École Polytechnique Fédérale de Lausanne

Planning & Design of Sanitation Systems and Technologies

450 notes

Do you want to learn how to plan affordable and context-specific sanitation solutions? Be up-to-date on the newest developments in urban sanitation planning and programming? Get to know best practice examples of urban sanitation systems in low- and middle-income countries? If yes, this course is for you! This course provides you with an introduction to integrated sanitation planning, both on a citywide scale and for specific contexts such as informal settlements. You will become familiar with different sanitation planning frameworks as well as different systems and technologies relevant along the sanitation value chain. You will learn why systems’ thinking is crucial for urban environmental sanitation, and how to apply key terminology and important concepts. INSTRUCTION Eawag-Sandec and EPFL jointly offer this course with support from sanitation experts of the World Bank and WHO. LANGUAGES We simultaneously offer this course in English and French. The name of the French course is « Planification & Design des Systèmes et Technologies d’Assainissement ». MOOC SERIES This course is one of four in the series “Sanitation, Water and Solid Waste for Development".

À partir de la leçon

Sanitation systems & technologies

After getting to know different sanitation planning frameworks in the first part of this week, you will learn about the key terminology and concepts used in the systems approach to environmental sanitation. We will also explore why systems thinking is crucial for urban environmental sanitation.

2.1 Introduction to the Compendium2:55

2.2 Sanitation Products9:37

2.3 Functional Groups6:42

2.4 User Interface Technologies16:58

2.5 Collection and Storage/Treatment - Single Pit Technologies9:20

2.6 Collection and Storage/Treatment - Double Pit Technologies12:01

2.7 Collection and Storage/Treatment - Anaerobic Technologies8:02

2.8 Conveyance - Container-based Technologies9:32

2.9 Conveyance - Sewer-based Technologies6:43

2.9b Conveyance - Condominial Sewerage Systems14:31

2.10 Summary Week 22:39

Rencontrer les enseignants

Christoph Lüthi
Dr.
Sanitation, Water and Solid Waste for Development / Eawag

Hello, and welcome to this module on sanitation products.

My name is Elizabeth Tilley, and I'll be presenting this module

as well as the next one on functional groups.

In this section, we're going to talk about the different types of products.

So the different liquids and solids

that go into and out of a sanitation system.

We have three goals in this module.

The first is to understand why it is important to consider

a range of sanitation products when you're planning a system.

Secondly, is to learn about what those different products are.

And third, is to be able to describe the characteristics

of each of those products, so we know how to best treat

and potentially use them later on.

Typically, when we think about sanitation, we think about two things, pee and poo.

So the liquid and solid excreta that come out of our bodies.

But in reality, there are a lot more elements to consider.

Certainly, urine and feces are two of the most important aspects to consider.

But there are also many other materials that make the sanitation system work.

Flush water, for example.

You can't have a sewer system without water to transport the urine and feces,

and in many dry cities around the world there is simply no flush water,

and therefore, you would need to consider a different form of transport.

There are other products that are generated

throughout the sanitation system.

Sludge, for example, is the thick, mucky layer

that forms at the bottom of a septic tank.

Sludge, because of its high solids content and viscosity, may be difficult to pump,

but it is also easily dried, and therefore can be used as a soil amender.

We'll come back to these examples later on.

Here is a fairly comprehensive list of the products that should be considered

when planning a sanitation system.

There are others of course that are not listed here,

but we'll focus on these ones for the remainder of this module

and throughout this course.

Let's start with primary products.

Primary products, or the input products, are those that enter the sanitation system

at the very beginning,

so they enter through the toilet.

Products of course, do not stay separate,

so they get combined and diluted.

They take on different names as this happens.

First we have urine, and feces.

The name for these two things together is excreta.

If you just add flush water to the feces, this is referred to as brownwater.

Brownwater only exists when urine is separated at the source,

and we'll talk more about this later in the module on technology.

When anal cleansing water, so that's the water that's used

for washing instead of toilet paper, or dry cleaning material,

are mixed in with the excreta and flush water,

the whole mixture is referred to as blackwater.

You may have heard of the term "waste water" before,

but blackwater is a more descriptive term,

and because any sort of unneeded water could be called waste water,

we prefer the term "black water"

to be more specific.

Greywater is the other water that's discharged from the house,

and may include all the other types of water

that are generated in the kitchen or from laundry, or from hand washing.

Here in this photo, from Maputo, Mozambique,

we can see two men collecting water in small storage containers.

If you can imagine the water it would take to flush a toilet constantly

in order to transport all of the household wastes in a toilet,

you can imagine how much work would be needed

to collect the quantity of water required.

It's one of these examples

where we would have to think of a different transport system

for the products that would be entering into the sanitation system.

Here we can see the different characteristics

of greywater, urine, and feces.

Looking first at volume, we see that the quantity of greywater generated

per person is immense.

Whereas the volume of feces, only 50 liters per person per year,

is relatively tiny.

We can see also that the majority of the nutrients,

nitrogen, phosphorous, and potassium,

are in urine, with a smaller amount in feces and very little in the greywater.

In the last row, we can see the quantities of fecal coliforms that are present,

and clearly, they are concentrated in the faeces.

Greywater has what may be a surprising amount,

and these come mostly from hand washing and showering.

Urine, you'll notice, has none.

The small star indicates that urine is pathogen free in the bladder

of healthy people, so pathogens in urine that is collected

outside of the body maybe still be pathogenic.

In summary then, we have large quantities of greywater,

with relatively no nutrient value.

Urine, which is generally clean, and nutrient rich,

and a very small amount of feces, that are highly pathogenic.

Knowing all of these characteristics can help us decide on the best ways

to store, transport, and use the products in our sanitation system.

Secondary products are those products that are generated

within the sanitation system, because of some type of transformation.

If you store urine for long enough, so about a month or so,

the pH and ammonia concentration will increase to the point

that it becomes self-sterilising.

So that means that most of the pathogens in the urine will be destroyed,

and that urine can safely be used as a nutrient source.

All that's needed for this type of transformation is time.

Similarly, faeces can be dried, simply in the presence of time and heat,

and once fully desiccated, the feces will be,

depending on the temperature and storage time, quite hygienic.

These processes, however, are only applicable to the products

if they are separate.

If excreta is left in a pit, remember the mixture

of urine and feces, and is allowed to degrade naturally and slowly over time,

the resulting product would be an organic material

not unlike compost or humus.

Blackwater, on the other hand, is a mixture of all the things

we discussed before, feces, flush water, toilet paper,

and after time, or with some kind of physical process,

the solids will separate, so that you'll be left

with two new products: a semi-clarified effluent,

and a dense sludge of the solids.

Here we can see a bit of what the sludge looks like.

It's a thin sludge, but it's still a typical sludge.

These are trucks that have collected the sludge from septic tanks

or pit latrines, and are discharging it onto an empty field, which unfortunately,

is not uncommon.

Fecal sludge must be removed constantly from many household level technologies,

and yet there are few treatment processes available that are able to treat it.

Here is a great example of a sludge drying bed.

The sludge trucks from the previous slide would come here, dump their sludge

onto one of these dedicated drying beds.

The beds are made from layers of gravel and sand.

The sludge layer is applied on top, and the solids stay on the sand layer

and dry out under the sun, while the effluent percolates

through the sand and down through the gravel, where it's collected.

The effluent, don't forget, is another new product

that must be treated in a separate process before it can be discharged

into the environment.

In the same way that sludge settles to the bottom of blackwater,

lighter particles will rise to the top.

FOGS: fats, oils, grease, and surfactants, F.O.G.S.

is the name given to all the frothy scum that floats to the top of a wastewater,

particularly greywater.

FOGS generally comes from the cooking fat and soaps that are used in the kitchen.

FOGS can clog pipes and pumps if it's not removed early

in the sanitation chain.

Here, you can see a nice example of a simple interceptor tank

that prevents the FOGS from entering into the small pipes.

After some time, that little strainer on the left will be used to remove

the FOGS and keep the small interceptor functioning well.

Most of the products that we've discussed so far are materials that are pathogenic

or harmful to the environment in some way,

but the products we're going to talk about here

are ones that can be produced by a sanitation system,

and are actually beneficial.

Compost, or humus, can be created with the dry fecal sludge

we saw in the earlier slide, simply by processing it

with some sort of organic material, like market waste.

Biogas, which is the result of anaerobic digestion,

and consists mostly of methane, can be collected and used as a fuel

for cooking and lighting.

These types of beneficial products are not difficult to produce,

but they must be considered in the early stages of sanitation planning

so that the most value from the system can be obtained without waste.

Here we see a diagram and an example of a fixed dome biogas reactor.

So just wrapping up what we've discussed so far:

There are a lot of products besides pee and poo that need to be considered.

Each product will contain a different quantity and variety

of nutrients and pathogens, which will influence the treatment requirements

and also the potential use options.

The volume of each product will great influence how it's transported

and treated within the sanitation system.

The range and type of products in a sanitation system

will determine the number, type, and sequence of technologies

that will be needed in the final design.

Choosing these technologies

will be discussed in the following modules.

In the next module, I will discuss the functional groups,

and I hope you will join me then.

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