关键词: 园林绿化废弃物, 堆肥, 覆盖, 热裂解, 外源添加剂

Abstract:

Green waste refers to branches, fallen leaves, grass clippings and other plant residues produced during urban greening management and maintenance processes, serving as organic-rich residues in urban ecological cycles, and its resource utilization is of great significance for promoting green and sustainable development. At present, the annual production of green waste in China reaches 70 million to 100 million tons, but the resource utilization rate remains below 10%, and traditional treatment methods face severe challenges, which seriously constrain the construction of modern cities, making the exploration of efficient resource utilization methods imperative. Composting technology is the core means to stabilize green waste and promote the return of organic matter to the soil. Under the synergistic action of microorganisms, the compost raw materials undergo the heating period, the thermophilic period and the cooling period in turn, completing the complex degradation and transformation process, and finally forming a high-quality product rich in humus. By adjusting the composting process and adding exogenous additives, we can not only improve the composting efficiency but also reduce greenhouse gas and ammonia emissions. Compost products have wide applications: they can serve as high-quality organic fertilizer to improve soil structure and enhance soil fertility; they can also be used as a cultivation medium to provide a good environment for plant growth; in the field of soil remediation, compost products can perform unique functions, including effectively passivating heavy metals, degrading organic pollutants, and helping the restoration and reconstruction of soil ecosystems. Ecological mulching technology can process green waste into two types of ground covering materials: bulk mulch and formed mulch. These mulch materials can not only improve soil properties, inhibit weed growth and dust, but also reduce the exposed area of the soil and beautify the urban landscape. In particular, the formed mulch, with its good water permeability, demonstrates great application potential in the construction of sponge cities, providing a new solution for urban rainwater management. As an emerging biomass energy utilization method, pyrolysis technology can convert green waste into three types of high value-added products: low-molecular liquid bio-oil, gaseous combustible gas and solid biochar. After further processing, these products can also be derived into a variety of new products with wide application prospects, representing the key technologies to promote the energy and materialization of green waste, and having high exploration value and development potential. At the same time, the resource utilization of green waste faces many challenges, such as the difficulty of degradation of high lignocellulosic plant residues, the serious carbon emissions in the composting process, and the high cost of bio-oil refining. Therefore, to comprehensively promote the resource utilization of green waste, it is necessary to deeply explore cutting-edge issues such as the development of high-efficiency microbial agents, low-carbon composting technology, covering technological innovation and high-value utilization of bio-oil, in order to seek to break through the bottleneck of key technologies. This paper systematically reviews the resource utilization system of green waste, analyzes its yield change trend, composting technology system and product application, ecological coverage technology and ecological benefits, pyrolysis technology and product advantages, elaborates the technical principles and application effects, and looks forward to the future challenges and frontier issues, aiming to provide systematic technical reference and practical guidance for the resource utilization of green waste.

Key words: green waste, composting, mulching, pyrolysis, exogenous additives