5. Conclusion
There is an urgent need of developing a mathematical model to
support decision-making regarding municipal solid waste management.
A mathematical model with integer linear programming and
mixed integer programming is developed. The model determined
the optimal number of waste management infrastructures or facilities
and suggested utilising the capacity of incinerator outside
Hong Kong to improve the waste problem.
The reason for adopting two programming approaches in a
model is to consider various user or technology conditions in
actual applications. If a user only has some preliminary data which
are restricted only to integers, it is appropriate to use the mathematical
approach with integer linear programming approach. If a
user has other specific data, which includes both integers and
non-integers, mixed integer programming approach is suggested
to be used to provide a more accurate solution. Decision makers
can choose different approaches based on their preferences and
actual situations.
As only preliminary data is available at Hong Kong, the model
uses integer linear programming to find out the range of nearly
optimal solutions. Mixed integer programming can be used to find
a solution based on the integer linear programming result when
more specific data is available. The mathematical model results
can support future waste management plans and policies.
The scope of this model focuses on waste flows between collection
points, incinerators, landfills and replacement truck warehouses.
This model primarily considers the collection of
recyclables and incineration as the processing systems. Other recycling
infrastructures and processes are out of the scope in this
study. Some factors such as environmental emission regulations,
inventory costs, and normal-time-over-time operation are
neglected to simplify the mathematical model. Further measurements
regarding particular parameters need to be conducted so
as to improve the accuracy of the estimated data