44 CHAPTER IV MODELING Before the simulation of scenarios is built, the existing model of plastic waste management should be developed first. The model building stage is very important in simulation approach in order to help author to have a deep understanding about how the behavior of the system in present time, and how to create the behavior as expected. The construction of existing model consists of input-output diagram construction that is explained thoroughly in section IV.1, and sub-systems identification in section IV.2. IV.1 Input-Output Diagram In system dynamic, input-output diagram is created in order to identify the big picture of the system generally. In input-output diagram, there are five main elements that are important to be indentified; uncontrollable inputs, controllable inputs, environmental inputs, desirable outputs, undesirable outputs, and the proposed scenarios to meet the desirable outputs. Figure IV-1 Input-Output Diagram for Integrated Plastic Waste Management Policy and rules, Public awareness Population growth rate, Waste generation rate, Plastics waste generation rate Minimum total cost (collecting, recycling, disposing, treatment), Maximum capacity (collecting, recycling, disposing, treatment) Environmental problem, Increasing of plastics waste disposal amount Integrated plastics waste management Plastics waste collected Plastics waste treated Plastics waste recycled Plastics waste disposed Simulation model of plastics waste management in Bandung Environmental inputsUncontrollable inputs Controllable inputs Undesirable outputs Desirable outputs Policy Implications Koleksi digital milik UPT Perpustakaan ITB untuk keperluan pendidikan dan penelitian 45 To understand the plastic waste management system, each element of categories will be described in brief as followed. Uncontrollable Inputs The uncontrollable input consists of a set of elements that have its own behavior cannot be controlled directly by the decision maker. Mostly, the elements deliver unpredicted results that can deliver the undesirable outputs or lead to a chaos in the system. Population growth rate in Indonesia is considered as one of the uncontrollable inputs in plastic waste management system. Although the government has widely spread the family planning campaign since years ago, still, there has not been any significant progress towards this issue. Therefore, the uncontrollable population growth in Bandung leads to the uncontrollable consumption and lifestyle and generate unpredicted amount of plastic waste. The amount of waste generated by the population in Bandung cannot be predicted and control directly by the government or private sector. Therefore, the amount of plastic waste is also become unpredictable input to the system. Controllable Inputs Controllable input is the element of a system that makes the decision maker or any stakeholders have ability to move a system around in its entire configuration space using only certain admissible manipulations. In plastic waste system, the elements that considered as controllable inputs are the amount of plastic waste collected, plastic waste treated, plastic waste recycled, and plastic waste disposed. Plastic waste collected can be controlled through the capacity of collectors managed by private sector or public service. Therefore, automatically, the amount of plastic waste to be treated will be as much as the amount of plastic waste collected. However, the proportion of recycle and reuse depend on the capacity and the current technology available. The improvement of proportion can be modified if the government can facilitate the recycling industries. Koleksi digital milik UPT Perpustakaan ITB untuk keperluan pendidikan dan penelitian 46 Environmental Inputs Environmental inputs in plastic waste system are policy and rules, and public awareness.