DOI: 10.14457/tu.the.2016.1768
title: A system dynamics study for efficient solid waste management through waste separation at source in Bangkok, Thailand

description: Waste management is a highly complicated process as its factors are intertwined and changed over time. Having accurate data of municipal solid waste (MSW) generation amount is an indispensable factor for effective planning of a municipal solid waste management (MSWM) system. However, to have an accurate estimation, significant waste generation factors have to be identified. In this dissertation, Bangkok is selected as a representative area of urban cities in developing countries. The city has struggled with consequences of a vast amount of waste generation and ineffective waste management system for decades. To alleviate the adverse impacts and increase effectiveness of the management system, waste minimization has become one of the most favorable waste management methods that provides tremendous contribution to the overall management system. However, to increase the overall MSWM efficiency, waste separation at source is imperative. The study aims to examine influential variables affecting generation amount and MSWM problems in Bangkok based on human attitudes. In addition, system dynamics (SD) approach is introduced as an alternative solution to see how likely the management system would be if waste separation at source is widely implemented.Questionnaire survey, interview, and site visit were methods of acquiring primary data. Statistical analyses were conducted using the methods of descriptive analysis, hypothesis testing, and Pearson correlation analysis. To learn the exact situation of waste management system, interview results were qualitatively evaluated by using the techniques of stakeholder analysis and TOWS matrix. To learn the significance of waste separation at source, simulations of SD models were performed in different scenariosThe results show 14 root causes of MSW generation in overall cases and seven MSW generation variables for the case of Bangkok. Respondents expressed their attitudes that MSW generation should be reduced and MSW should be managed effectively. At the current MSWM situation, respondents stated that they received a moderate level of service due to problems such as bad odor, leftover waste, and no service provision. Accordingly, solutions are given through the stakeholder analysis and TOWS matrix, which present options that the (Bangkok Metropolitan Administration) BMA can adopt to its strategic MSWM planning.This study shows interdisciplinary research on the analysis of human aspects towards having partnerships for sustainably effective MSWM. The results of stakeholders’ relationships and roles that can be used as potential solutions to increase effectiveness in MSWM service are identified. On service providers’ point of view, this study shows hidden problems that truly happen to service recipients. With respect to partnerships, respondents and experts agree that all stakeholders are necessary to collaborate for improvements of MSWM. The most possible way to start improving MSWM service provision in Bangkok is that the BMA can launch a long-term policy to attract all related stakeholders to harmoniously work towards sustainable MSWM.There is high willingness to conduct waste separation at source and waste minimization. A SD modeling approach is applied to represent the influence of attitudinal ambivalence on MSWM service performance. The proposed SD model presents cause and effect relationships of MSWM factors showing the reinforcing impacts of the influence of different rates of source separation. Moreover, the influence of source separation incentives and MSWM knowledge related factors on human attitudes towards sustainable MSWM system is clarified. From all six scenarios, source separation has direct impact on the performance of waste collection and transportation process. Simulation results show that the current situation of 8% recyclable separation rate does not increase the efficiency of collection service. However, when residents separate organic waste at the same rate, a consideration amount of waste will be diverted from landfill. When the separation rate increases to be 40% or 80%, the results show less amount of waste left to be landfilled, less management cost, and higher MSWM service efficiency. Moreover, collected recyclable and organic waste can be used for many useful purposes. To increase the effectiveness of MSWM system, the most plausible approach for the BMA is to promote waste separation at source by starting at organic waste. The study shows that, more involvement of people in source separation allows better MSWM service provision. If Bangkok residents sort only recyclable waste, amount of collected waste to be transported to landfill will be decreasing over time. However, the amount of MSW reduction is remarkably different comparing to the case that the population conducts both recyclable and organic waste separation.