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1.8 Waste disposal / Landfills - part 2

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发展中国家城市固体垃圾管理

洛桑联邦理工学院

4.8（1,423 個評分） | 48K 名學生已註冊

Have you come across large piles of garbage in neighbourhoods and streets and smelly waste disposal sites polluting the environment of low- and middle-income countries? Do you want to know what kind of sustainable solutions are appropriate to better manage waste and enhance recycling and recovery? If yes, this course is for you! This course provides you with an overview of the municipal solid waste management situation in low- and middle-income countries. It covers key elements of the waste management system, such as its technical, environmental, social, financial and institutional aspects. Besides understanding the challenges, you will be introduced to appropriate and already applied solutions through selected case studies.

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Energy, Economy, Natural Resources, Environmental Protection

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4.8（1,423 個評分）

5 stars
1,180 ratings
4 stars
229 ratings
3 stars
14 ratings

MP

May 30, 2016

This was a great overview of the techniques and issues in solid waste management. They put together some great resources as well if you wanted to expand your learning on any of the topics.

GG

Feb 18, 2019

The course was great to follow and was really informative, furnishing me with information that could be used right after completion. Thank you very much for putting this course together!

從本節課中

Physical Elements of Solid Waste Management

The course begins with an overview of the current waste management situation in developing countries. We will introduce the Integrated Sustainable Waste Management framework that will guide you through this course. The modules of this first week deal with the physical components of municipal solid waste management. Connect with your peers and check out the bonus modules at the end of the week. ******************** SEMANA 1: ELEMENTOS FÍSICOS DE LA GESTIÓN DE LOS RESIDUOS SÓLIDOS: El curso comienza con una visión general de la situación actual de la gestión de los residuos sólidos en los países en vías de desarrollo. Introduciremos el marco de la Gestión Integrada y Sostenible de los Residuos Sólidos que te guiará a través de este curso. Los módulos de esta primera semana tratan de los componentes físicos de la gestión municipal de los residuos sólidos. Conéctate con tus compañeros y revisa los módulos adicionales al final de la semana. ******************** SEMAINE 1: ÉLÉMENTS MATÉRIELS DE LA GESTION DES DÉCHETS SOLIDES: Le cours commence par un aperçu de la situation actuelle de la gestion des déchets dans les pays en développement. Nous vous présenterons le cadre de gestion intégrée et durable des déchets qui vous guidera tout au long de ce cours. Les modules de cette première semaine traitent des composantes physiques de la gestion des déchets municipaux. Connectez-vous avec vos collègues et découvrez les modules bonus à la fin de la semaine.

1.1 Overview of the course7:16

1.2 Why is this course important?6:44

1.3 Municipal waste generation and characterization13:55

1.4 Waste collection & transport10:42

1.5 Improving efficiency of waste collection and transport12:40

1.6 Recycling municipal waste16:12

1.7 Waste disposal / Landfills - part 18:14

1.8 Waste disposal / Landfills - part 211:13

1.9 Upgrading a Dump Site10:00

1.10 Key messages Week 14:47

教學方

Dr. Christian Zurbrügg
Imanol Zabaleta
Félix Schmidt

腳本

Now, let's speak about landfill construction.

We will see some important elements to be considered for building

a new landfill.

It is usually very difficult to find a new landfill site, especially

near the big cities, for different technical and political reasons.

It is often impossible to find a site which meets all the environmental

and economic criteria.

For that reason, a lot of cities have transformed progressively

their dumpsite in controlled landfill.

This is the case of Rio de Janeiro, but also of Geneva, for example.

Along all the criteria required for a new landfill, I will focus

on a limited number of unusual ones.

First, geological quality and natural protection of the underground

water resources is certainly the main environmental and known criteria.

Another criteria is the site position in the service region.

In terms of traffic, as we mentioned before, the best place

for a landfill is the center of gravity of the region.

Each kilometer away from this center represents, in average,

two more kilometers for each truck all along the year.

This has an impact on the environment and on the cost.

An important criteria is to have a big surface and a long-term

available volume.

It is important to build a landfill for 30 or 50 years.

For that, it is necessary to build the first steps and to have

another possibility to create future cells for the next years.

Other point is to have a local availability of earthen material

for covering the works or for covering the different steps of the landfill.

Landfills need a very big volume of such material to cover the waste.

For that, it is eventually partially possible to use inert construction

materials but also local quarries are necessary to have the required material.

These local quarries can be the next cells of the landfill.

Otherwise, the transport cost will be too high to make a good job.

Impermeable base layer is important to reduce the infiltration

of wastewater in the ground.

Many European norms are proposing plastic impermeable layers.

These plastic solutions are expensive, extremely fragile in

the construction and the operation phases.

Here, in an example in Albania, we can see holes made by machines

during the construction or the first months of operation.

To make such plastic layer needs a high technical experience and control.

But why to spend so much money for this plastic technology if

then the plastic layer is full of holes?

I'm largely in favor of using mineral layers using local materials

available locally.

This needs some geotechnical knowledge in order to find in the

region a good material that can be compacted, with a high density

and a low permeability.

Normally, we need to mix different proportions of sandy material

with clay and to strongly compact it in two or three layers

of twenty or thirty centimeters.

Here, in this example, we can see a mineral layer made by natural

local material mixed with clay material.

These technologies are not very far from the road construction

techniques and you definitely need a good geotechnical engineer

to conduct the operation.

But, mineral layers will give you a very long term, good and

stable impermeable system.

And remember: if we have petrol today, it's due to the impermeable

quality of clay.

The rainwater flowing through the waste becomes highly polluted.

We call that substance the leachate.

It is very important to have a very good drainage system of

this leachate on the bottom of the waste.

Here, we have the bottom of the waste with the impervious system

and here the drainage system.

This drainage system is important for two reasons.

First, the leachate quantity then can flow through in the nature

through the impervious layer is directly proportional of the

height of the water on the top of the bottom of the landfill.

If we have a good drainage, we reduce this height to a very

limited level and then reduce infiltration in the nature.

Second reason, as we mentioned before, the accumulation of water

on the bottom of the landfill will increase the risk of instability

and, for this reason, it is very important to take this water

out of the waste.

The leachate has generally a high potential of clogging the drainage.

To avoid that, the leachate drainage is realized through a continuous

drainage layer of twenty or thirty centimeters of pervious material.

It is possible to use inner-construction waste for that – like

bricks or concrete waste.

The best is to add drainage tubes with a design allowing a future

access from outside for possible control and cleaning of the main tubes.

A slope of a minimum 3 percent, 2-3 percent, must be considered.

All around the landfill, a big drainage system must be constructed

in order to avoid that the water enters the waste.

Additionally, it is also important to capture and evacuate the

rainwater coming in the top of the landfill and to avoid a possible

erosion effect of the covered top.

The degradation of the organic matter without oxygen produces

methane as well as little proportion of other gases producing

very bad odors for the human nose.

Methane production has, moreover, a very high contribution to

the greenhouse effect on climate.

Then, the gas drainage and burning has two important functions:

reduce the bad odors for the population; reduce the greenhouse effects.

These are different techniques for gas drainage.

As we saw, the most common are to realize stone stack during

the development of the landfill.

This can be done through a simple accumulation of stones or

inner-materials – inner-metallic tube – which is elevated layer by layer.

The accumulation of stones creates a continuous vertical drainage

stack and the metallic tubes

can be used very easily to fire the gas coming from the waste.

This gas represent a huge energetic potential.

In the second step, the gas can be collected through a pumping

system to a motor-generator that will produce a continuous production

of electricity.

These technologies exist and are very efficient.

The economic interest of this electricity production is strongly

dependent of the price of the electricity but, important to

mention, is that such system requires a high technology as well

for the gas drainage system as for the preventive maintenance of the motor.

The design of the tube collecting the gas to the pumping station

should be done considering a high settlement of the waste during

the life of the landfill.

This will create some technical problems but can be solved.

Honestly, the landfill leachates are very difficult to be treated.

Usual biological process for urban wastewater have a very limited

efficiency on that kind of water.

On another hand, it makes no sense to build and pay an expensive

impermeable layer in plastic or mineral at the base of the landfill

if the leachates are just collected and then discharged in the

environment downstream the landfill and without treatment.

Depending on the climate, the best solution is often to store

the drained leachate in big basin and then to pump it and to

recycle it in the waste system.

This needs to have a pumping system and an infiltration system

with drains that allow the leachate to enter again in the waste.

This storage and recirculation have many beneficial effects.

First, it will treat and partially evaporate the leachate water.

Secondly, it will increase the gas production and then the electric

production in cases of a gas-to-energy system is in place.

It will generate an important volume reduction of the waste;

the production of gas will reduce organic composition of the

waste and this gain in volume will give an interesting economic

value and increase the landfill life.

The volume of the leachate basin has to be defined according

to local climate conditions along the years.

Main points of landfill construction are to use local material,

implicate geotechnical engineer, control the water, capture and burn gas.

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