Planning for sustainable municipal solid waste management
Practical Action
Landfill and incineration
Why is planning this important? Waste which is not carefully disposed of or processed can
present a serious threat to public health and the environment. Planning involves many
stakeholders as well as climatic, economic and even geological considerations. Getting all this
right is important and can make improved disposal and treatment a realistic prospect.
Disposal is one of the most problematic aspects of solid waste management in low-income
countries. Waste characterisation data will prove useful in planning disposal options. The
quantities of waste generated will help you decide what volume of landfill site is required and,
according to trends in waste production, enable you to project its lifespan. Waste composition
data will also help guide your decisions about suitable options: for example the presence of toxic
waste will indicate the need for particular care in disposal, and a high organic/moisture content
could make incineration very difficult. Key planning issues include:
Identifying and understanding practices at present, including issues (e.g. corruption)
which may impact performance now and in the future;
For landfilling, where could a disposal site be situated, what are the pervading geological
conditions, where does the water table lie, and what regulations must be adhered to (e.g.
environment agency)?
For incineration, is the waste composition suitable (often drier waste with a high
proportion of plastics is particularly suitable), is safe technology affordable and would it
be possible to maintain and operate it to sufficiently high standards?
Fully engineered sanitary landfill is the safest disposal option in terms of human health and the
environment, and methane can be recovered for electricity generation. Engineered landfill sites
are usually very expensive to construct and operate so may be a more suitable long-term
objective. Incineration, involving high-temperature complete combustion of organic material,
can be used to reduce volume and in some situations energy can be recovered. Open burning of
waste is not incineration and is not recommended because it releases toxic smoke. Controlled
incinerators can be developed relatively cheaply, but the high moisture content of waste in many
low-income countries can cause problems. Most waste incinerators are costly to develop and
operate.
In many cases a carefully managed basic landfill site will be more achievable in the short run,
involving the following practices:
Preventing all burning (spontaneous or intentional) at the site;
Locating the site at least 500 m downwind from housing and water sources on a
geologically suitable site;
Daily compacting and covering with soil, to increase stability and discourage vermin;
Basic monitoring of dumping, ideally using a weigh-station if available;
Fencing to prevent waste blowing outside the site; and,
Basic leachate control.
Leachate is liquid runoff, and is a particular problem in rainy conditions. It has a high
'biological oxygen demand' and can damage ecosystems in water bodies. It may also contain
toxins such as heavy metals, which can pollute groundwater sources.
A local authority wants to design a basic landfill site to serve a town of population 10,000
to operate for 5 years. Based on generation rates of 0.5kg/ person, total waste generated each
day equals 5000 tonnes. With a density of 500Kg/m3, total volume per day is [Total
waste/density] = 10 m3/ day. Each year the total volume will be [10 m3 x 365 days] = 3650m3,
and for 5 years [3650*5] = 18250 m3. This is equivalent to a site approximately 50m x 50m
wide x 8m deep.
In fact, the estimate above may be inaccurate for a number of reasons:
Over time waste will compact and its density increase. In addition, some of the liquid in
waste will evaporate or be removed for treatment. These factors will tend to prolong the
life of the disposal site.
Waste generation rates, as well as the size of the town, may drastically increase in a five
year period. Additionally, daily covering of waste with soil will tend to increase the rate
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