is landfilled in Dandora dumpsite and the rest is
open-dumped (UNEP 2010). The Nairobi City
Council (NCC) has the primary responsibility for
the provision and regulation of solid waste
management services in the city. However, the
collection efficiency is quite low and the total
amount of waste that is being improperly disposed of is 2,140 tons/day (UNEP 2010). With
time, other actors such as private companies and
community-based organizations have come into
play. These actors handle waste on a smaller
scale and are irregular in their services.
Nairobi is divided into administrative districts,
each having different population density. The
Dandora (Nairobi East district) and Kibera (Nairobi West district) are considered as high-density
zones with 36% and 22% of the population living
in those districts, respectively (Khamala and Alex
2013). In this study, we conduct the economic and
environmental assessment of composting the waste
generated in the densely populated area of the
Nairobi West district. We assume that of the 2,140
ton/day of waste generated in Nairobi, 22% of the
waste is generated from the West district and is
targeted for composting. The MSW is to be
composted in small decentralized compost plants,
each having a capacity of 10.5 ton/day of incoming waste. Therefore, to absorb the waste generated in the West district (470 ton/day), 45 small
scale decentralized compost plants are needed.
Figure 1 shows the location of the proposed
decentralized compost plants and as shown in the
figure, there are already existing compost plants in
the Nairobi Western district.
3 The Nexus Approach to Economic
Assessment of Nutrient Recovery
Models
Human interactions with the components of the
ecosystems lead to changes in the services
derived from that particular ecosystem. The shift
towards sustainable production and consumption
practices related to waste management programmes have received wide attention in the
nexus of resources conservation, recovery and
reuse (Pires et al. 2011). The core idea of nexus
thinking is maximizing synergies and reducing
trade-offs through integrated management of
more than one resource (Hettiarachchi and
Ardakanian 2016). In the case of resource
recovery and reuse, waste generated from different waste streams is being tapped for recovering resources such as nutrients, energy and
water. Processing of organic waste for nutrient
recovery for use as a soil amendment has a
positive impact on soil quality indicating that
there exists a strong inter-connectivity in watersoil-waste nexus (Fig. 2) (Lal 2015).
Application of nutrients recovered from
organic waste in agriculture contributes to
counteracting issues such as soil nutrient depletion or affordability of fertilizers and will result in
improved soil quality and farm productivity
thereby increasing food security and conserving
ecosystem services. Through nutrient recovery
models, synergies are created among different
sectors such as the waste management and food
Table 1 Composition of
MSW at the source and
community waste
collection points
Waste
City-wide waste composition (%)
At immediate source
At communal waste collection pits
Organics
50.9
43.0
Paper
17.5
12.1
Plastics
16.1
15.1
Glass
2.0
5.6
Metals
2.0
2.7
Others
11.4
21.7
Source UNEP (2010)
Nutrient Recovery for Use in Agriculture …
27
open-dumped (UNEP 2010). The Nairobi City
Council (NCC) has the primary responsibility for
the provision and regulation of solid waste
management services in the city. However, the
collection efficiency is quite low and the total
amount of waste that is being improperly disposed of is 2,140 tons/day (UNEP 2010). With
time, other actors such as private companies and
community-based organizations have come into
play. These actors handle waste on a smaller
scale and are irregular in their services.
Nairobi is divided into administrative districts,
each having different population density. The
Dandora (Nairobi East district) and Kibera (Nairobi West district) are considered as high-density
zones with 36% and 22% of the population living
in those districts, respectively (Khamala and Alex
2013). In this study, we conduct the economic and
environmental assessment of composting the waste
generated in the densely populated area of the
Nairobi West district. We assume that of the 2,140
ton/day of waste generated in Nairobi, 22% of the
waste is generated from the West district and is
targeted for composting. The MSW is to be
composted in small decentralized compost plants,
each having a capacity of 10.5 ton/day of incoming waste. Therefore, to absorb the waste generated in the West district (470 ton/day), 45 small
scale decentralized compost plants are needed.
Figure 1 shows the location of the proposed
decentralized compost plants and as shown in the
figure, there are already existing compost plants in
the Nairobi Western district.
3 The Nexus Approach to Economic
Assessment of Nutrient Recovery
Models
Human interactions with the components of the
ecosystems lead to changes in the services
derived from that particular ecosystem. The shift
towards sustainable production and consumption
practices related to waste management programmes have received wide attention in the
nexus of resources conservation, recovery and
reuse (Pires et al. 2011). The core idea of nexus
thinking is maximizing synergies and reducing
trade-offs through integrated management of
more than one resource (Hettiarachchi and
Ardakanian 2016). In the case of resource
recovery and reuse, waste generated from different waste streams is being tapped for recovering resources such as nutrients, energy and
water. Processing of organic waste for nutrient
recovery for use as a soil amendment has a
positive impact on soil quality indicating that
there exists a strong inter-connectivity in watersoil-waste nexus (Fig. 2) (Lal 2015).
Application of nutrients recovered from
organic waste in agriculture contributes to
counteracting issues such as soil nutrient depletion or affordability of fertilizers and will result in
improved soil quality and farm productivity
thereby increasing food security and conserving
ecosystem services. Through nutrient recovery
models, synergies are created among different
sectors such as the waste management and food
Table 1 Composition of
MSW at the source and
community waste
collection points
Waste
City-wide waste composition (%)
At immediate source
At communal waste collection pits
Organics
50.9
43.0
Paper
17.5
12.1
Plastics
16.1
15.1
Glass
2.0
5.6
Metals
2.0
2.7
Others
11.4
21.7
Source UNEP (2010)
Nutrient Recovery for Use in Agriculture …
27