A multi-objective optimization model for strategic waste management master plans

The optimization of solid waste management strategies is challenging due to the various alternatives and objectives, particularly in terms of the material and energy recovery systems. This paper presents a systematic optimization framework that identifies the most beneficial set of waste to energy (WTE) management strategies through non-linear mathematical modelling. The proposed model determines the optimum allocation of the different waste streams to selected waste management facilities, including material recovery facilities (MRFs), incinerators, anaerobic digestion (AD) plants, and sanitary landfills with gas recovery. The waste generated was divided into three streams, namely readily biodegradables, recyclables, and non-recyclables. The model objectives included maximum material and energy recovery, financial profitability, as well as minimum carbon footprint. The optimum hybrid strategy was based on the relative importance of each objective, which was acquired through a Fuzzy Analytic Hierarchy Process (AHP). The optimization framework was tested to generate an optimum 20-year hybrid waste management strategy for an example country, the United Arab Emirates (UAE). The optimum strategy included the complete allocation of readily biodegradable waste to AD plants up to the 14th year, followed by gradual disposal in landfills for additional waste. All MRF rejects and non-recyclables were disposed in landfills throughout the assessment period. The multi-objective optimum strategy would recover enough energy to cover approximately 4.2 of the total energy demand in the UAE while reducing around 97.6 of the carbon footprint from landfilling. In terms of the net present value, the optimum hybrid strategy would increase profitability by about 288 compared to the existing practices in the UAE. © 2020 Elsevier Ltd