situation, which could be taken to generally
represent Kenya’s status, is largely characterized
by low coverage of solid waste collection, pollution from uncontrolled dumping of waste,
inefficient public services, unregulated and
uncoordinated private sector and lack of key
solid waste management infrastructure (Njoroge
et al. 2014). These practices of open dumping of
MSW have negative impacts on the environment
and people’s health.
Increasingly the “nexus-approach” is gaining
importance in environmental resources management and it is thought to be one of the means to
achieve sustainability (Hoff 2011). This approach
goes beyond looking at the individual components and integrates the functioning, productivity
and management of the interlinkages and interdependencies across sectors. One such nexus link
is water, soil and waste, where the production of
food relies on water and soil, and waste contributes an important factor to the provision of
nutrients and other organic material (Hettiarachchi and Ardakanian 2016). The conversion
of the organic fraction of MSW into secondary
valuable products such as compost reflects
another linkage of the nexus. Recovering and
reuse of resources is at the core of thinking when
applying the nexus approach (Schwärzel et al.
2015). This approach creates financial and environmental sustainability and presents a great
opportunity to mitigate the prevailing waste
management problems in developing countries
while addressing soil nutrient depletion and
environmental pollution.
Composting of MSW has been done for several years; however, the success of such businesses has been limited in developing countries.
The potential economic, environmental and
social impacts of composting MSW need to be
assessed to ensure its sustainable development.
While composting can be a proposed mechanism
to meet the water, soil and waste nexus (see
Bouma 2021), it is important to assess the socioeconomic feasibility of composting options
based on the scale of operation. In many developing countries, large centralized and highly
mechanized composting plants have often failed
to produce good quality compost. Centralized
composting plants are often abandoned due to
high operational and maintenance costs. In contrast, decentralized composting ensures separation of organic waste either at the household
level by creating awareness of resource recovery
or at community levels and thus creating
employment opportunities for the urban poor.
The decentralized composting approach reduces
high capital investments on mechanization,
operation and maintenance costs, which can
make use of low-cost technologies based on
manual labor to ensure waste is well sorted
before it is composted. The transportation of
waste from densely populated areas is an additional challenge and most of the waste remains
uncollected posing negative environmental and
health externalities to the population at large.
This study, therefore, hypothesizes that setting
up of decentralized plants in areas where population density is higher, significantly reduces
environmental and health externalities and provides a business opportunity in the urban context.
Therefore, the main focus of the study is to
assess the financial and environmental viability
of a decentralized compost business model in the
densely populated areas of Nairobi.
2 Generation and Composition
of Municipal Solid Waste
in Nairobi
In Nairobi, 3,125 tons of household waste is
generated daily
1 along with 1,467 tons of nonhousehold waste indicating that household waste
comprises about 68% of the total waste generated
in the city (UNEP 2010). Table 1 shows the
characteristics and composition of the MSW
generated in Nairobi city. The organic fraction of
the waste comprises 50.9% while the rest is paper
(17.5%), plastic (16.1%), glass (2%), metal (2%)
and other miscellaneous waste (11.4%). The
estimated current reuse and recycling is merely
100–150 tons/day, while about 830 tons of waste
1
Projected household waste for 2016 considering
0.69 kg/capita/day of waste generated (UNEP 2010).
26
S. Gebrezgabher et al.
represent Kenya’s status, is largely characterized
by low coverage of solid waste collection, pollution from uncontrolled dumping of waste,
inefficient public services, unregulated and
uncoordinated private sector and lack of key
solid waste management infrastructure (Njoroge
et al. 2014). These practices of open dumping of
MSW have negative impacts on the environment
and people’s health.
Increasingly the “nexus-approach” is gaining
importance in environmental resources management and it is thought to be one of the means to
achieve sustainability (Hoff 2011). This approach
goes beyond looking at the individual components and integrates the functioning, productivity
and management of the interlinkages and interdependencies across sectors. One such nexus link
is water, soil and waste, where the production of
food relies on water and soil, and waste contributes an important factor to the provision of
nutrients and other organic material (Hettiarachchi and Ardakanian 2016). The conversion
of the organic fraction of MSW into secondary
valuable products such as compost reflects
another linkage of the nexus. Recovering and
reuse of resources is at the core of thinking when
applying the nexus approach (Schwärzel et al.
2015). This approach creates financial and environmental sustainability and presents a great
opportunity to mitigate the prevailing waste
management problems in developing countries
while addressing soil nutrient depletion and
environmental pollution.
Composting of MSW has been done for several years; however, the success of such businesses has been limited in developing countries.
The potential economic, environmental and
social impacts of composting MSW need to be
assessed to ensure its sustainable development.
While composting can be a proposed mechanism
to meet the water, soil and waste nexus (see
Bouma 2021), it is important to assess the socioeconomic feasibility of composting options
based on the scale of operation. In many developing countries, large centralized and highly
mechanized composting plants have often failed
to produce good quality compost. Centralized
composting plants are often abandoned due to
high operational and maintenance costs. In contrast, decentralized composting ensures separation of organic waste either at the household
level by creating awareness of resource recovery
or at community levels and thus creating
employment opportunities for the urban poor.
The decentralized composting approach reduces
high capital investments on mechanization,
operation and maintenance costs, which can
make use of low-cost technologies based on
manual labor to ensure waste is well sorted
before it is composted. The transportation of
waste from densely populated areas is an additional challenge and most of the waste remains
uncollected posing negative environmental and
health externalities to the population at large.
This study, therefore, hypothesizes that setting
up of decentralized plants in areas where population density is higher, significantly reduces
environmental and health externalities and provides a business opportunity in the urban context.
Therefore, the main focus of the study is to
assess the financial and environmental viability
of a decentralized compost business model in the
densely populated areas of Nairobi.
2 Generation and Composition
of Municipal Solid Waste
in Nairobi
In Nairobi, 3,125 tons of household waste is
generated daily
1 along with 1,467 tons of nonhousehold waste indicating that household waste
comprises about 68% of the total waste generated
in the city (UNEP 2010). Table 1 shows the
characteristics and composition of the MSW
generated in Nairobi city. The organic fraction of
the waste comprises 50.9% while the rest is paper
(17.5%), plastic (16.1%), glass (2%), metal (2%)
and other miscellaneous waste (11.4%). The
estimated current reuse and recycling is merely
100–150 tons/day, while about 830 tons of waste
1
Projected household waste for 2016 considering
0.69 kg/capita/day of waste generated (UNEP 2010).
26
S. Gebrezgabher et al.