4.2b Etude de cas d’Erdos, Chine - Un projet pilote de ville écologique [2]

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En provenance du cours de École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

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École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

84 notes

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 ».

À partir de la leçon

Solutions pour l’assainissement urbain – Cas d’étude

Dans cette semaine on va vous présenter un choix de cas d’étude d’Afrique et d’Asie montrant différentes solutions d’assainissement de l’échelle du quartier à l’échelle nationale.

4.1 Etude de cas de Nala, Népal – Mise en œuvre de l’approche CLUES14:43

4.2a Etude de cas d’Erdos, Chine - Un projet pilote de ville écologique [1]9:02

4.2b Etude de cas d’Erdos, Chine - Un projet pilote de ville écologique [2]5:28

4.3a Etude du cas indonésien - Comment la situation de l’assainissement en Indonésie fut transformée [1]10:41

4.3b Etude du cas indonésien - Comment la situation de l’assainissement en Indonésie fut transformée [2]12:50

4.4 Etude de cas de Lusaka, Zambie - Prestation de services de gestion des boues de vidange12:05

Rencontrer les enseignants

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

Welcome back to our second module

on the Erdos, China case study.

In the last module we presented the case

of the Erdos eco-san pilot project

and highlighted some of its unique features:

the first multi-story source-separating dry toilet project in China,

and the closed loop nutrient recovery processes

that were implemented.

In this module, we are going to analyze some of the problems

and challenges that cropped up very early

after the residents had moved in,

and eventually led to the low levels of user satisfaction

shown in the graph here,

and finally led to the total dismantling of the dry sanitation system in 2010.

This graph highlights the four main grievances and issues at play

that explain the high rate of dissatisfaction.

The institutional, financial, and socio-cultural aspects.

By far, the most important are the technical aspects.

The main issue here was new toilet technology

that was not yet robust and mature enough

to stand the wear and tear of everyday use.

This was due to mechanical parts that malfunctioned,

and the incorrectly installed ventilation system

that was compounded by broken fans.

This led to major odor problems and huge complaints by the residents.

Also, the fans were perceived as being too loud

when they were in operation.

A further problem common to urine separating dry toilets

was the crystallization of urine in the odor locks.

Some of these failures can be explained

by the installation of a totally new system

and the lack of experience by the local builders

in installing them.

Secondly, the socio-cultural aspects.

The Erdos apartments were bought by aspiring,

upwardly mobile apartment owners

who never really accepted the toilets

and perceived them as being inferior technology.

This non-acceptance led to the incorrect use,

for example, using water to flush

as shown here,

or throwing solid waste into the toilet bowl.

These problems were highlighted

by an evaluation conducted by SEI.

The two graphs on the bottom left

show that a majority of interviewed households

were ashamed of using their toilets,

and thought they lowered the value of their apartment.

Thirdly, the financial aspects certainly also played a role.

The entire capital and maintenance costs

proved to be more than twice as high

as a conventional water-flushed sanitation system,

and especially the maintenance cost with mechanical emptying

of waste bins and urine were seen as costly.

The ecological benefits like the water savings

were not perceived as a great benefit by the homeowners.

And finally, the institutional aspects

that led to some of the abovementioned problems.

During the project implementation,

there was not a clearly developed understanding

of the responsibilities and duties

between local government and the main developer.

The diverse interests of the three main stakeholders

were also a major issue.

The Stokholm Environmental Institute

was mainly interested in promoting ecological sanitation

in a multi-story building.

The Dongxeng District government

was interested in having a solution for water shortages

and also promoting an image as a modern city.

And lastly, the Doxing Estate development company

was of course, interested in making a profit.

In hindsight, the incorporation of a single management entity

would probably have led to less building mistakes

and less technical failures

when implementing something totally new.

In the end, three and a half years after moving in,

and despite attempts at installing a newer generation of dry toilet

called the Separette,

and improving and widening the ventilation pipes

and replacing the fans,

the homeowners collectively decided to replace the entire dry toilet system

and replace them with low flush, water-based cistern toilets.

The only remaining part of the project today

is the onsite treatment plant

which acts as a decentralized wastewater treatment plant.

This module provided only a short insight

into some of the challenges of trying,

ultimately without success,

to introduce novel closed-loop sanitation systems

in a multi-story context.

It does not mean that dry sanitation systems cannot work <i>per se</i>,

but that mature and robust technology solutions

need to be aligned with user expectations and aspirations.

If you want to learn more about this interesting project

and details about how the whole story played out,

you can order this book from Practical Action Publishers,

which we've included in this week's list of further reading.

In our last and final case study

we will move to Indonesia

and present one of the great success stories

of bringing urban sanitation to scale.

This module will be presented by Isabel Blackett

from the Water and Sanitation program in Jakarta.

Thanks, and see you next week.

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