A decision-making model incorporating the life cycle assessment for the optimal recycling of spent fluorescent lamps in Bangkok and the vicinity

Abstract

Spent fluorescent lamps (SFLs) are a product that must be recycled by using special technology because fluorescent lamps (FLs) contain toxic elemental mercury. A study of the Pollution Control Department (PCD) in 2004 indicated that SFLs discarded in Thailand include approximately forty-five million lamps per year. The study also suggested that the demand for fluorescent lamps was growing due to the population growth and economic development. Proper recycling planning for used lamps in the future is thus important. If the location sites for the recycling plants, percents of recycling and the capacity of the recycling plants are not properly designed, it will consume high levels of energy, materials and cost, and generate high environmental impacts from the life cycle of the product. A main problem, however, is making the optimum decision for the recycling of SFLs which is a complicated problem. To solve this problem, a decision-making model for creating the optimal plan for the recycling of SFLs was developed in this study as a tool for decision makers. The objective of the model was to minimize the environmental impact arising from significant activities in the life cycle of the recycling of SFLs while meeting budget constraints. The model determined what the optimal percents of recycling are, where the best possible locations for building recycling plant expansions would be, as well as what the optimal capacity of a recycling plant expansion is. This will be useful for policy-makers in setting up a national policy of waste management arising from SFLs for improving the global environmental quality under a controlled budget. The procedure was started with a detailed process flowchart of all concerned activities for available technology used to manage SFLs, then an inventory analysis was done, and all concerned models including those for inventory, environmental impact and cost –benefit, were prepared. Finally, a decision making model was developed from the linkage of all these concern models together. A complex algorithm was also written and the computer model formulation was done. While their model input parameter values were collected, hypothetical recycling plants were also specified for the case study areas including Bangkok and surrounding provinces in Thailand. Model explorations were done, while the optimum results for SFL planning in the case study areas were investigated. The results indicated that the optimum recycling percentages in the study areas were in the range of 85% - 89% with a 20 year planning horizon. Following the requirements for the recycling plants, 2 locations were indicated. The first one was located in Samutprakarn province and the second, in Pathumthani province. The first location was required for 33 units in the recycling plant (one unit can recycle 1,269,000 SFLs), while the other was required for 2 units. As a result,, the total environmental impact was minimized to 1,549,315,401 units (in a single score unit), while the net present value (NPV) of benefit was more than the NPV of cost at about 8,482,510 Baht.