Estimation and assessment of cost and revenue for solid waste management subsystems in Tehran city using mathematical functions

The municipality of Tehran has recently attempted to implement the integrated waste management system (IWMS) with the approach of minimizing environmental emissions, the lowest cost and the maximum utilization of existing potential. The present study set out with the aim of assessing the fixed and variable investment costs along with estimating the cost functions of its subsystems.
Recorded data from September to October in 2014- 2015 were used, making arrangements well in advance. The annual waste input to each subsystems of IWMS was firstly divided into 0 to twice of input ratio. The amount of fixed and variable investment costs along with future costs were then determined considering experts’ opinions. Finally, MATLAB software version 7.1 was used in order to coding, estimating cost functions, and determining the correlation coefficient (R2) between the input and cost values.
The results showed that transportation subsystem allocated the maximum amount of costs (43%). Processing (23%), anaerobic digestion (12%), aerobic digestion (9%), landfilling (7%), and incineration (6%) were ranked in the next positions, respectively. Furthermore, using actual cost data based on existing capacity as well as peer reviewed experts’ data with theoretical capacity indicated that all subsystems had economic scale with high correlation coefficients.
It is concluded that directing the waste flow from burial site to other waste processing technologies such as separation of recyclable materials, aerobic digestion, anaerobic digestion, and incineration would result in a significant reduction in the total amount of costs.