2.8 Transport - Technologies de vidange manuelle ou motorisée

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Del curso dictado por École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

80 calificaciones

École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

80 calificaciones

Désirez-vous apprendre à mettre en œuvre des solutions d’assainissement abordables et adaptées à différents contextes ? Voulez-vous connaître les derniers développement dans le domaine de la planification de l’assainissement urbain ? Êtes-vous intéressés par des exemples de systèmes d’assainissement urbain qui fonctionnent dans les pays à faible et moyen revenu ? Si oui, alors ce cours est pour vous ! Le cours débute par une introduction à la planification intégrée de l’assainissement et adresse aussi bien la planification à l’échelle de la ville que la planification dans des contextes spécifiques tels que les quartiers informels. Après un survol des différentes approches de planification de l’assainissement, vous aurez l’occasion de passer en revue les différents systèmes et technologies possibles, la terminologie et concepts clé, et comprendre pourquoi il est crucial de réfléchir en termes de « système intégré » pour la planification de l’assainissement urbain. Le cours couvre toute la chaîne de l’assainissement et fournit de l’information détaillée sur les systèmes d’assainissement adaptés aux contextes à faibles et moyen revenus (par exemple, des systèmes basés sur les fosses sèches, des systèmes décentralisés avec différents réseaux d’égout, le transport des eaux noires). Eawag-Sandec et EPFL offrent ce cours conjointement avec des experts en assainissement de la Banque Mondiale et de l’OMS. SERIE DE MOOC « EAU, ASSAINISSEMENT ET DÉCHETS SOLIDES DANS LES CONTEXTES DU DÉVELOPPEMENT » Ce cours est l’un des quatre cours de la série « Eau, Assainissement et Déchets Solides dans les Contextes du Développement ». VERSION ANGLAISE DE CE COURS Ce cours est offert simultanément en français et en anglais. Le nom du cours en anglais est « Planning & Design of Sanitation Systems and Technologies ».

De la lección

Systèmes & Technologies d’Assainissement

Après avoir présenté différents cadre de planification de l’assainissement, vous aborderez l’approche de systèmes pour l’assainissement environnemental, la terminologie et les concepts-clés ainsi que les raisons pour lesquelles une pensée en termes de « système » est crucial pour l’assainissement urbain.

2.1 Introduction au Compendium2:56

2.2 Produits issus de l’assainissement9:37

2.3 Groupes fonctionnels6:42

2.4 Technologies d’interface utilisateur16:58

2.5 Collecte et Stockage/Traitement - Technologies à fosse unique9:20

2.6 Collecte et Stockage/Traitement - Technologies à double fosse12:01

2.7 Collecte et Stockage/Traitement - Technologies anaérobies8:02

2.8 Transport - Technologies de vidange manuelle ou motorisée9:34

2.9 Transport - Types de systèmes d’égouts6:43

2.10 Résumé de la 2ème Semaine2:39

Conoce a los instructores

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

Hello, and welcome to this module on conveyance technologies.

My name is Philippe Raymond. I'm an environmental engineer

working at Eawag SANDEC on sanitation planning

in international development projects.

I will be presenting the different conveyance

and treatment technologies.

In the last modules, Lukas Ulrich introduced you to the user interface

and collection and storage technologies.

Now the question is: what happens when the pit is full?

How do we transport waste water or sludge out of a neighborhood?

Well, there are two categories of conveyance,

or transport systems.

On the one side, the sewered systems,

relying on pipe networks, and on the other side,

the non-sewered systems, relying on different kinds

of container-based solutions, upon which we are focused

in this module.

The different sewer systems will be presented in the next module.

We have three learning goals for this module.

First, to get to know the different ways to transport

sanitation products.

Secondly, to get an integrated view

of manual and motorized emptying. And finally, to understand

the pros and cons of the different technologies.

Let's start.

We will take a look at different ways

to transport sanitation products, focusing first on manual ways,

and then on motorized ways.

Many development projects focus only on drinking water supply

or the provision of latrines.

However, in both cases, building new infrastructure

also implies new sanitation products,

which need to be transported and properly treated.

These products, which we call here "output products," can be,

for example, blackwater and greywater, sludge,

urine, dried feces, or pit humus,

according to the technologies that are implemented.

We will focus now on the transport

of products from on-site sanitation systems,

and more specifically, the conveyance of sludge,

or, if you prefer, fecal sludge, or septage.

When a pit is full, people have the choice between two options:

either they let the pit overflow, which is both a nuisance

and a health hazard for the neighborhood,

or they call manual or motorized service providers to empty their pit.

The most efficient and hygienic way

in such a case is the use of pumping trucks.

However, in low-income contexts, the use of trucks

is often not possible.

The main reasons are either that there is no access for trucks,

that the sludge is too thick to be pumped,

or that the household cannot afford the often costly service.

Thus, people often resort to manual emptyings.

Unfortunately, most of the time, manual emptying looks like this.

Hard work in very unhygienic conditions,

provoking hostility from neighbors.

Manual emptiers face very harsh conditions

and, at the same time, lack recognition for their work.

The situation can be improved with proper equipment

and technologies.

Human-powered emptying of pits, vaults, and tanks

can be done in two ways: either with buckets and shovels

or using a portable, manually operated pump

specially designed for sludge, such as the Gulper,

the Rummer, or the MAPET.

Manual sludge pumps are relatively new inventions

and are still being optimized.

Sludge hand pumps -- here, the Gulper --

work on the same concept as water hand pumps.

Here's the operator, who pushes and pulls the handle.

The sludge is pumped up and discharged through the spout.

It can then be collected in barrels, bags, or carts,

and removed in a quiet, hygienic way.

Next to that, it is important also to ensure

that workers are adequately protected with gloves, boots,

face mask, and overall.

It is important to mention that proper equipment

and organization help the manual emptiers

to gain recognition and acceptance.

Sanitation programs should strive to legitimize

the work of the laborers and create the right

enabling environment by providing permits and licenses,

as well as helping to legalize the practice.

Let's now look at motorized emptying.

Motorized emptying refers to vehicles equipped

with a motorized pump and a storage tank.

Namely, pumping trucks, or vacuum trucks.

Generally, the storage capacity of a vacuum truck

is between 3 and 12 cubic meters.

Pumping trucks come in all size and shapes,

as shown here in these four pictures.

They can be locally manufactured, which ensures that maintenance skills

and spare parts are available.

A drawback, however, may be limited efficiency.

Smaller vehicles have also been developed to access areas

with narrow pathways, where normal trucks cannot access.

Let's look now at the pros and the cons

of motorized and manual emptying.

The main advantages of motorized emptying

are that it is fast and efficient, and it minimizes health risks.

However, it has high capital costs, as well as operation

and maintenance costs.

These costs are often passed on to the customer,

who sometimes cannot afford them.

Besides, the trucks cannot pump thick sludge,

garbage in pits may block the hose, and the pumps really only suck

to a depth of 2 to 3 metres.

Trucks may also have difficulties with spatial access, and spare parts

may not always be available.

The main advantages of manual emptying

are low operation maintenance costs,

the possibility to access every pit,

and the availability of maintenance skills

and spare parts.

However, it has a limited efficiency

and is a time-consuming activity.

And it implies health hazards when not done properly.

As said before, it is tough work.

Besides, it requires a disposal pump nearby, within 500 meters.

In both cases, proper disposal of the sludge is a challenge.

Distance has a cost, but not only.

Traffic jams, police checkpoints, bad state of the roads

may add to the costs and turn into hindrances

for such conveyance to treatment plants.

Emptying service providers aim to reduce distance and time

for each trip, save fuel, protect their truck,

and minimize the problems with the population.

All these aspects need to be taken into account

when selecting options and designing

a fecal sludge management scheme.

Distance is a critical issue.

If the distance from the collection points to the treatment plant

is too long, there is a possibility of building transfer stations.

Transfer stations can be underground holding tanks

where manual emptiers or small scale motorized service providers

bring their sludge.

The sludge is then further conveyed by vacuum trucks.

Another option is a sewer discharge station,

where sludge is directly discharged into an existing main sewer line.

In that case, it is important to manage discharges

with care in order not to overload an existing

waste water treatment plant.

Transfer stations can be a useful interface

between informal settlements where vacuum trucks cannot access,

and formal settlements, where municipal

or private motorized service providers are active.

They have to be carefully located and well maintained

to minimize odors and problems to nearby residents.

To sum up, we saw that container based conveyance is much more

a management and institutional issue than a technical problem.

It needs to be addressed when building any type of latrines

and collection and storage system.

Most cities in low-income countries rely mainly

on on-site sanitation systems.

Container-based conveyance is not an exception.

It is rather a norm.

So far, it remains mainly a private sector business,

in which, unfortunately, most sludge ends up

untreated in the environment.

Proper management schemes and sustainable financial arrangements

need to be put in place for the sludge to be treated,

for the service providers to be recognized and legalized,

and to reduce the health hazards

both for the workers and for the neighboring population.

Above all, we have to remember that conveyance

to proper disposal points has a cost.

The critical aspect is to estimate this cost

and see how it can be shared between the different

sanitation stakeholders.

To learn more about fecal sludge management,

about manual and motorized emptying,

and how to plan a sustainable fecal sludge management scheme,

we strongly recommend the recently published

Eawag Sandec FSM book that you can download for free

at the link shown below.

In the next section, I will be presenting

the sewer based conveyance technologies.

See you then.

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