The Carbon Emission and Environmental Benefit Analyses of the Qingxi River Sediment Treatment and Recycling Project in Dongguan, China

In this paper, the ability of resource treatment of black smelly river sediment to reduce life-cycle greenhouse gas (GHG) emissions and its environmental benefits were calculated using the US EPA life-cycle assessment (LCA) model. Different from previous studies, this paper used the willingness-to-pay method to determine the weight factors of various environmental impact types in this study and proposed a calculation model of carbon emissions and environmental benefits in the whole process of resource utilization of sediment, rather than a new method to treat black smelly river sediment. Take the Qingxi River sediment treatment and recycling project in Dongguan, China, as an example: the carbon reduction, environmental impact, and environmental benefit of different stages of sediment treatment are calculated. The results show that 93.419 kg of carbon dioxide, 0.202 kg of methane, and 0.001 kg of nitrous oxide are produced for 1 t of river sediment, in which the preparation process of unburned brick contributes 99% of carbon dioxide, 82.67% of methane, and 100% of nitrous oxide emissions and is the stage that produces the most greenhouse gases. The 1 t of sediment resource treatment can reduce the generation of 29.066 kg carbon dioxide and 0.855 kg of methane. The comprehensive net environmental benefit of processing 1 t of river sediment is 1.492 yuan, and the environmental benefit is 1.684 times the environmental cost. This study identified that the treatment and recycling of river sediment has better environmental benefits. The preparation process of unburned brick can be optimized to further reduce carbon emissions and produce better environmental benefits.