Green waste characteristics and sustainable recycling options

Green waste is a diverse mixture of biomass mainly generated through site clearing and landscape maintenance in inhabited areas, which requires appropriate management to address sustainability concerns. However, the recycling potential and technological applicability of green waste remain poorly understood possibly due to limited knowledge of its complicated generation and composition characteristics. This review provides a comprehensive overview of the scope, generation, characteristics, and mainstream recycling technologies of green waste. Based on our synthesis, the average annual green waste generation is around 47 kg/person, but differences in performance vary between countries. The green waste generation is mainly related to green space area, radiation, and rainfall. In the light of the characteristics of nutrient and lignocellulose contents, separately recycling the green (grass and leaves) and brown parts (branches) is identified as a promising approach. From both environmental and economic perspectives, the brown part is suitable for energy recovery, while composting for nutrients recovery is more preferred for the green part. This study highlights that proper combination of recycling technologies would turn green waste into a valuable resource, which would help move towards a more resource-efficient and circular economy to address future sustainability challenges. [Display omitted] •We review current research on green waste characteristics and recycling technologies.•The annual per capita green waste generation is 47 kg at the global scale.•Green waste generation is mainly related to green space area, radiation, and rainfall.•Separate collection and recycling of the green and brown parts are recommended.