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Chapter 7
Solid waste management
Solid waste refers here to all non-liquid wastes. In general this does not include excreta,
although sometimes nappies and the faeces of young children may be mixed with solid
waste. Solid waste can create significant health problems and a very unpleasant living
environment if not disposed of safely and appropriately. If not correctly disposed of, waste
may provide breeding sites for insect-vectors, pests, snakes and vermin (rats) that increase
the likelihood of disease transmission. It may also pollute water sources and the environ-
ment.
7.1 Associated risks
7.1.1 Disease transmission
Decomposing organic waste attracts animals, vermin and flies. Flies may play a major role in
the transmission of faecal-oral diseases, particularly where domestic waste contains faeces
(often those of children). Rodents may increase the transmission of diseases such as
leptospirosis and salmonella, and attract snakes to waste heaps.
Solid waste may also provide breeding sites for mosquitoes. Mosquitoes of the Aedes genus
lay eggs in water stored in discarded items such as tins and drums; these are responsible for
the spread of dengue and yellow fevers. Such conditions may also attract mosquitoes of the
Anopheles genus, which transmit malaria. Mosquitoes of the Culex genus breed in stagnant
water with high organic content and transmit microfilariases (Médecins Sans Frontières,
1994), appropriate conditions are likely to arise where leachate from waste enters pooling
water.
In times of famine or food scarcity, members of the affected population may be attracted to
waste heaps to scavenge for food; this is likely to increase the risk of gastro-enteritis,
dysentery and other illnesses.
7.1.2 Pollution
Poor management of the collection and disposal of solid waste may lead to leachate pollution
of surface water or groundwater. This may cause significant problems if the waste contains
toxic substances, or if nearby water sources are used for water supplies.
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Where large quantities of dry waste are stored in hot climates this may create a fire hazard.
Related hazards include smoke pollution and fire threat to buildings and people.
7.1.3 Effect on morale
The effect of living in an unhygienic and untidy environment may lead people to become
demoralised and less motivated to improve conditions around them. Waste attracts more
waste and leads to less hygienic behaviour in general.
7.2 Sources and types of solid waste
7.2.1 Sources of solid waste
In most emergency situations the main sources of solid waste are:
! Medical centres
! Food stores
! Feeding centres
! Food distribution points
! Slaughter areas
! Warehouses
! Agency premises
! Markets
! Domestic areas
Appropriate solid waste management strategies may vary for institutional, communal and
domestic sources, depending on types and volumes of waste. Waste from medical centres
poses specific health hazards and for this reason is considered separately in Chapter 8.
7.2.2 Type and quantity of waste
The type and quantity of waste generated in emergency situations varies greatly. The main
factors affecting these are:
!
the geographical region (developed or less-developed country or region);
! socio-cultural practices and material levels among affected population;
! seasonal variations (affecting types of food available);
!
the stage of emergency (volume and composition of waste may change over time); and
!
the packaging of food rations.
In general, the volume of waste generated is likely to be small and largely degradable where
the population is of rural origin and the food rations supplied are unpackaged dry foodstuffs.
Displaced urban populations are more likely to generate larger volumes of non-degradable
waste, especially where packaged food rations are provided.
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Guideline values suggest that each person is likely to produce 0.5-1.0 litres of refuse per day
with an organic content of 25 to 35 per cent and a moisture content between 10 and 60 per
cent (Adams, 1999). However, this is likely to vary greatly and estimates should be made
locally.
Different categories of solid waste include:
Organic waste:
Waste from preparation of food, market places, etc.
Combustibles:
Paper, wood, dried leaves, packaging for relief items, etc. (high
organic and low moisture content)
Non-combustibles: Metal, tin cans, bottles, stones, etc.
Ashes/dust:
Residue from fires used for cooking
Bulky waste:
Tree branches, tyres, etc.
Dead animals:
Carcasses of domestic animals and livestock
Hazardous waste:
Oil, battery acid, medical waste
Construction waste: Roofing, rubble, broken concrete, etc.
Children and solid waste in a refugee camp, Turkey
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Collected market waste, Tanzania
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7.3
Initial steps
In order to establish effective solid waste management in the affected area the following
process should be used:
Figure 7.1. Initial steps in solid waste management
Identify the sources of waste
Identify the types of waste
Determine the potential health hazards from waste
Determine the volume of waste generated
Identify safe collection method/s
Identify safe transportation method/s
Identify safe disposal method/s
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7.4 Key components of solid waste management
Solid waste management can be divided into five key components:
! Generation
! Storage
! Collection
! Transportation
! Disposal
7.4.1 Generation
Generation of solid waste is the stage at which materials become valueless to the owner and
since they have no use for them and require them no longer, they wish to get rid of them.
Items which may be valueless to one individual may not necessarily be valueless to another.
For example, waste items such as tins and cans may be highly sought after by young children.
7.4.2 Storage
Storage is a system for keeping materials after they have been discarded and prior to
collection and final disposal. Where on-site disposal systems are implemented, such as
where people discard items directly into family pits, storage may not be necessary. In
emergency situations, especially in the early stages, it is likely that the affected population
will discard domestic waste in poorly defined heaps close to dwelling areas. If this is the
case, improved disposal or storage facilities should be provided fairly quickly and these
should be located where people are able to use them easily. Improved storage facilities
include:
! Small containers: household containers, plastic bins, etc.
! Large containers: communal bins, oil drums, etc.
! Shallow pits
! Communal depots: walled or fenced-in areas
In determining the size, quantity and distribution of storage facilities the number of users,
type of waste and maximum walking distance must be considered. The frequency of
emptying must also be determined, and it should be ensured that all facilities are reasonably
safe from theft or vandalism.
7.4.3 Collection
Collection simply refers to how waste is collected for transportation to the final disposal site.
Any collection system should be carefully planned to ensure that storage facilities do not
become overloaded. Collection intervals and volumes of collected waste must be estimated
carefully.
7.4.4 Transportation
This is the stage when solid waste is transported to the final disposal site (see 7.6 for more
details). There are various modes of transport which may be adopted and the chosen method
depends upon local availability and the volume of waste to be transported. Types of
transportation can be divided into three categories:
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! Human-powered:
open hand-cart, hand-cart with bins, wheelbarrow, tricycle
! Animal-powered:
donkey-drawn cart
! Motorised:
tractor and trailer, standard truck, tipper-truck
7.4.5 Disposal
The final stage of solid waste management is safe disposal where associated risks are
minimised. There are four main methods for the disposal of solid waste:
! Land application: burial or landfilling
! Composting
! Burning or incineration
! Recycling (resource recovery)
The most common of these is undoubtedly land application, although all four are commonly
applied in emergency situations. Details of disposal on-site and off-site can be found in
Sections 7.5 and 7.7 respectively.
7.5 On-site disposal options
The technology choices outlined below are general guidelines for disposal and storage of
waste on-site, these may be adapted for the particular site and situation in question.
7.5.1 Communal pit disposal
Perhaps the simplest solid waste management system is where consumers dispose of waste
directly into a communal pit. The size of this pit will depend on the number of people it
serves. The long-term recommended objective is six cubic metres per fifty people. The pit
should be fenced off to prevent small children falling in and should generally not be more
than 100m from the dwellings to be served. Ideally, waste should be covered at least weekly
with a thin layer of soil to minimise flies and other pests. Figure 7.2 illustrates a simple
communal pit.
Advantages: It is rapid to implement; and requires little operation and maintenance.
Constraints: The distance to communal pit may cause indiscriminate disposal; and waste
workers required to manage pits.
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Earth mound to
keep surface water
out of the pit
Fence around
the pit
Waste layers
Once full, backfill the pit
with at least 0.5m of soil cover
Wire mesh covering
pit contents
0.1m layerof
soil/ash to cover
each layer of waste
Figure 7.2. Communal solid waste pit
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7.5.2 Family pit disposal
Family pits may provide a better long-term option where there is adequate space. These
should be fairly shallow (up to 1m deep) and families should be encouraged to regularly
cover waste with soil from sweeping or ash from fires used for cooking. This method is best
suited where families have large plots and where organic food wastes are the main compo-
nent of domestic refuse.
Advantages: Families are responsible for managing their own waste; no external waste
workers are required; and community mobilisation can be incorporated into hygiene promo-
tion programme.
Constraints: Involves considerable community mobilisation for construction, operation and
maintenance of pits; and considerable space is needed.
7.5.3 Communal bins
Communal bins or containers are designed to collect waste where it will not be dispersed by
wind or animals, and where it can easily be removed for transportation and disposal. Plastic
containers are generally inappropriate since these may be blown over by the wind, can easily
be removed and may be desirable for alternative uses. A popular solution is to provide oil
drums cut in half (Figure 7.3). The bases of these should be perforated to allow liquid to pass
out and to prevent their use for other purposes. A lid and handles can be provided if
necessary.
Handles
Lid
Hammered
edges
Holes in base
Gravel bed
for drainage
Half oil drum
Support stand
Figure 7.3. Communal bin made from an old oil drum
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In general, a single 100-litre bin should be provided for every fifty people in domestic areas,
every one hundred people at feeding centres and every ten market stalls. In general, bins
should be emptied daily.
Advantages: Bins are potentially a highly hygienic and sanitary management method; and
final disposal of waste well away from dwelling areas.
Constraints: Significant collection, transportation and human resources are required; sys-
tem takes time to implement; and efficient management is essential.
7.5.4 Family bins
Family bins are rarely used in emergency situations since they require an intensive collection
and transportation system and the number of containers or bins required is likely to be huge.
In the later stages of an emergency, however, community members can be encouraged to
make their own refuse baskets or pots and to take responsibility to empty these at communal
pits or depots.
Advantages: Families are responsible for maintaining collection containers; and potentially
a highly sanitary management method.
Constraints: In general, the number of bins required is too large; significant collection,
transportation and human resources are required; takes time to implement; and efficient
management essential.
7.5.5 Communal disposal without bins
For some public institutions, such as markets or distribution centres, solid waste manage-
ment systems without bins can be implemented, whereby users dispose of waste directly onto
the ground. This can only work if cleaners are employed to regularly sweep around market
stalls, gather waste together and transport it to a designated off-site disposal site. This is
likely to be appropriate for vegetable waste but slaughterhouse waste should be disposed of
in liquid-tight containers and buried separately.
Advantages: System rapid to implement; there is minimal reliance on actions of users; and it
may be in line with traditional/usual practice.
Constraints: Requires efficient and effective management; and full-time waste workers
must be employed.
7.6 Transportation options
Where bins or collection containers require emptying, transportation to the final disposal
point is required. As described, waste transportation methods may be human-powered,
animal-powered or motorised.
7.6.1 Human-powered
Wheelbarrows are ideal for the transportation of waste around small sites such as markets but
are rarely appropriate where waste must be transported considerable distances off-site.
Handcarts provide a better solution for longer distances since these can carry significantly
more waste and can be pushed by more than one person. Carts may be open or can be fitted
with several containers or bins.
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7.6.2 Animal-powered
Animal-powered transportation means such as a horse or donkey with cart are likely to be
appropriate where they are commonly used locally. This may be ideal for transportation to
middle distance sites
7.6.3 Motorised
Where the distance to the final disposal site is great, or where the volume of waste to be
transported is high, the use of a motorised vehicle may be the only appropriate option.
Options include tractor and trailer, a standard truck, or a tipper-truck, the final choice
depending largely on availability and speed of procurement.
Figure 7.4 illustrates a number of refuse collection vehicles and containers.
©WEDCWEH1204
Figure 7.4. Refuse collection containers and vehicles
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For large volumes of waste it may sometimes be appropriate to have a two-stage transporta-
tion system requiring a transfer station. For example, waste is transported by handcart to a
transfer station where it is loaded into a truck to be taken to an off-site disposal site several
kilometres away (Figure 7.5).
7.7 Off-site disposal options
The technology choices outlined below are general options for the final disposal of waste off-
site.
7.7.1 Landfilling
Once solid waste is transported off-site it is normally taken to a landfill site. Here the waste is
placed in a large excavation (pit or trench) in the ground, which is back-filled with excavated
soil each day waste is tipped. Ideally, about 0.5m of soil should cover the deposited refuse at
the end of each day to prevent animals from digging up the waste and flies from breeding
(Figure 7.6).
The location of landfill sites should be decided upon through consultation with the local
authorities and the affected population. Sites should preferably be fenced, and at least one
kilometre downwind of the nearest dwellings.
Advantages: A sanitary disposal method if managed effectively.
Constraints: A reasonably large area is required.
Emptying of cart
at transfer station
Side board for increasing
loading capacity
Ramp
Figure 7.5. Emptying a cart at a transfer station
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7.7.2 Incineration
Although burning or incineration is often used for the disposal of combustible waste, this
should generally only take place off-site or a considerable distance downwind of dwellings.
Burning refuse within dwelling areas may create a significant smoke or fire hazard, espe-
cially if several fires are lit simultaneously. Burning may be used to reduce the volume of
waste and may be appropriate where there is limited space for burial or landfill. Waste should
be ignited within pits and covered with soil once incinerated, in the same manner as
landfilling. The same constraints for siting landfill sites should be applied here also.
Previous days refuse
Backfill with excavated soil
after each day of waste tipped
1.5m
to
2.0m
0.5m
0.5m
0.5m
0.5m
Ground level
Ground level
New refuse
Ground level
Stage 1
Stage 2
Stage 3
Old refuse
Figure 7.6. Simple landfilling
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Advantages: Burning reduces volume of combustible waste considerably; and it is appropri-
ate in off-site pits to reduce scavenging.
Constraints: There can be smoke or fire hazards.
7.7.3 Composting
Simple composting of vegetables and other organic waste can be applied in many situations.
Where people have their own gardens or vegetable plots, organic waste can be dug into the
soil to add humus and fibre. This makes the waste perfectly safe and also assists the growing
process. This should be encouraged wherever possible, particularly in the later stages of an
emergency programme.
Properly managed composting requires careful monitoring of decomposing waste to control
moisture and chemical levels and promote microbial activity. This is designed to produce
compost which is safe to handle and which acts as a good fertiliser. Such systems require
considerable knowledge and experience and are best managed centrally. In general, they are
unlikely to be appropriate in emergencies.
Advantages: Composting is environmentally friendly; and beneficial for crops.
Constraints: Intensive management and experienced personnel are required for large-scale
operations.
7.7.4 Recycling
Complex recycling systems are unlikely to be appropriate but the recycling of some waste
items may be possible on occasions. Plastic bags, containers, tins and glass will often be
automatically recycled since they are likely to be scarce commodities in many situations. In
most developing country contexts there exists a strong tradition of recycling leading to lower
volumes of waste than in many more developed societies.
Advantages: Recycling is environmentally friendly.
Constraints: There is limited potential in most emergency situations; and it is expensive to
set up.
7.8
Intervention levels
Table 7.1 indicates general intervention strategies for the storage and disposal of solid waste
in different emergency scenarios.
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7.9 Protective measures
In order to minimise disease transmission there are several protective measures that can be
undertaken. These concern equipment for staff and the siting and management of disposal
sites.
7.9.1 Staff
It is important that workers employed to collect and transport solid waste are provided with
appropriate clothing and equipment. Gloves, boots and overalls should be provided wherever
possible. Where waste is burned, or is very dusty, workers should have protective masks.
Water and soap should be available for hand and face washing, and changing facilities should
be provided where appropriate.
7.9.2 Siting of disposal sites
The location of all disposal sites should be determined through consultation with key
stakeholders including local government officials, representatives of local and displaced
populations, and other agencies working in the area. Appropriate siting should minimise the
effects of odour, smoke, water pollution, insect vectors and animals.
Table 7.1. Recommended interventions for different scenarios
Scenarios and
recommended
interventions
Immediate
action
Short-term
measure
Long-term
measure
The affected
population go
through a transit
camp immediately
after a disaster
The affected
population remain
in a temporary
location for up to
six months
The affected
population
stay in the
affected area
immediately
after a disaster
The affected
population move
to a new area
and are likely
to remain for
more than a year
! Clearing of scattered waste
! Burning and burial of waste on site
! Temporary communal pits
! Temporary communal bins and off-site disposal
! Repairing or upgrading of existing facilities
! Communal pits
! Family pits
! Communal bins and off-site disposal
! Communal pits
! Family pits
! Communal bins and off-site disposal
! Repairing or upgrading of existing
facilities
! Recycling
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On-site disposal is generally preferred since this requires no transportation and staff needs
are low. This is appropriate where volumes of waste are relatively small, plenty of space is
available and waste is largely organic or recyclable.
If the volumes of waste generated are large, or space within the site is severely limited, it may
be necessary to dispose of waste off-site. Where off-site disposal is to be used the following
measures should be taken in selecting and developing an appropriate site:
! Locate sites at least 500m (ideally 1 kilometre) downwind of nearest settlement.
! Locate sites downhill from groundwater sources.
! Locate sites at least 50m from surface water sources.
! Provide a drainage ditch downhill of landfill site on sloping land.
! Fence and secure access to site.
Careful assessment should be made to determine who owns the proposed site and to ensure
that apparently unused areas are not in fact someone’s farm or back yard.
References and further reading
Adams, John (1999) Managing Water Supply and Sanitation in Emergencies. Oxfam:
Oxford.
Ali, Mansoor, Cotton, Andrew and Westlake, Ken (1999) Down to Earth: Solid waste
disposal for low-income countries. WEDC, Lougborough University: UK.
Cairncross, S. and Feachem, R. (1983) Environmental Health Engineering in the Tropics: An
introductory text. John Wiley & Sons, Chichester.
Davis, Jan and Lambert, Robert (1996) Engineering in Emergencies: A practical guide for
relief workers. RedR / IT Publications: London.
Médecins Sans Frontières (1994) Public Health Engineering in Emergency Situation. Médecins
Sans Frontières: Paris.
Reed, R. and P.T. Dean, P.T. (1994) Recommended Methods for the Disposal of Sanitary
Wastes from Temporary Field Medical Facilities Disasters Vol 18, No 4.