Designing a sustainable collection and transportation routes for domestic wastes in the agro-pastoral ecotone of the Tibetan Plateau

Abstract

The absence of an efficient and safe routes for the timely collection and transportation of domestic waste (DW) may have negative effects on the environment and public health. However, the existing collection and transportation routes (CTR) for domestic waste (DW) based on territorial management are not suitable for the special socio-ecological system of the agro-pastoral ecotone (APE). Therefore, it is crucial to develop a low-cost, high-efficiency, and risk-free CTR to mitigate the threat of DW to the environmental sustainability in the APE of the Tibetan Plateau. This study selected Haidong as a research case and constructed a sustainable CTR optimization framework based on an integrated perspective on temporal, spatial and eco-safety risk. We used the improved Ant Colony Optimization (ACO) to simulate optimal spatial-temporal routes, and the eco-safety risk level of the CTR was assessed by using the Minimum Cumulative Resistance model (MCR). Results demonstrated that: (1) After the sustainable model was optimized, the total transportation mileage and the frequency of collection and transportation were reduced by 45.88% and 38.07% respectively, the economic cost savings were decreased by 32.29%. Optimized routes were more effective and can better adapt to the dispersed pollution-producing characteristics in the APE. (2) The optimized routes reduced greenhouse gas (GHG) emissions by 41.09%, and reduced the eco-safety risk of the high and relative high-risk routes, which account for 29.05% of total routes, can protect important ecological functions and reduce the adverse impacts of DW transportation on soil, atmosphere, water, and the living environment. (3) The cores of adaptive management for sustainable CTR in APE were to change from the current single-county administrative organization to a cross-county administrative organization; adjust the transportation cycle based on pollution-producing characteristics; sort the DW locally; and cultivate environmental awareness among farmers and herdsmen. This study designed new sustainable collection and transportation routes for domestic waste to improve environmental sustainability in the agro-pastoral ecotone.