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Recycling-equilibrium strategy for phosphogypsum pollution control in phosphate fertilizer plants

Xu, Jiuping, Fan, Lurong, Xie, Yachen, Wu, Gang
Journal of cleaner production 2019 v.215 pp. 175-197
decision making, economic theory, emissions, income, issues and policy, models, phosphogypsum, phosphorus fertilizers, pollution, pollution control, socioeconomic development, uncertainty, wastes
Excessive phosphogypsum waste has caused significant environmental contamination and has consequently become a serious threat to sustainable socio-economic development. This paper proposes a recycling-equilibrium strategy from a regional policy perspective that integrates circular economic theory and modeling techniques to resolve phosphogypsum-related pollution problems. Specifically, three typical conflicts are analyzed to describe the problem complexity, and a multi-objective bi-level programming model is formulated under uncertainty for the assignment of practical disposal limits to achieve a compromise agreement between the multiple decision makers. A solution approach that employs fuzzy theory, an acceptable reduction target, and Karush-Kuhn-Tucker conditions is developed to identify the optimum phosphogypsum stack allowance allocation mechanism for regional authorities and an optimal purchase-transportation plan for the phosphate fertilizer plants. The results from the practical case validated the feasibility and efficiency of the formulated method and proved that a recycling-equilibrium strategy based stack allowance allocation mechanism could successfully achieve phosphogypsum pollution mitigation. The practical application findings were: (1) different phosphate fertilizer plants have different sensitivities towards changing stack reduction targets; (2) local authority revenue and phosphogypsum stack quantities are mainly impacted by environmental protection targets; (3) allocating larger stack allowances to phosphate fertilizer plants with smaller emissions coefficients can realize better phosphogypsum reduction.