Shanghai's parks, green spaces, roadside trees, residential units, and living quarters generate around 350,000 tons of green waste annually. Typically viewed as urban garbage that needs to be cleared and disposed of, they also contain organic matter needed for agriculture and urban green spaces.
Similar resources can be found in kitchens, restaurants, food processing facilities, and even wastewater generated from building operations. Through sorting, detection, and proper treatment, a portion of kitchen waste, coffee grounds, branches, and domestic sewage can be converted into fertilizers, soil conditioners, and irrigation water.
Cities are not just the end point for consuming agricultural resources, but also continuously produce water, nutrients, and biomass. The real issue is: how to organize these scattered, low-value, and potentially polluted residues into a supply chain that can stably return to agriculture.
On the subject of returning to the land, the most tangible manifestation is the food waste generated in cities.
"Roads of Tomorrow" podcast host Jing, who has long been focused on and reporting on environmental practices, told Fast Company China that in the community composting practices they have come into contact with, "wet materials" with higher water content, such as kitchen waste and fruit peels, are usually mixed with materials like leaves, twigs, and coffee grounds for aerobic composting. After fermentation and maturation, these leftover materials from kitchens and daily consumption can re-enter community gardens, urban green spaces, or return to farmland.
However, food waste is only part of the city's organic waste. Another larger and more easily overlooked resource comes from urban greening.
Urban roadside trees, parks, and community green spaces undergo multiple prunings and natural shedding every year, continuously generating garden waste such as branches, leaves, grass clippings, and flowers. In 2022, when the Ministry of Housing and Urban-Rural Development launched a pilot program for the treatment and resource utilization of urban park garden waste, it summarized these materials as being "widely distributed, strongly seasonal, high in transportation costs, highly renewable, and versatile in utilization methods." After classification, crushing, and maturation, different types of garden waste can be made into organic mulch, soil improvement substrates, bio-organic fertilizers, and can also be used for biomass fuel and garden path paving.
Their scale is not small. According to data released by the Shanghai Municipal Greening and City Appearance Management Bureau in 2026, the maintenance of parks, green spaces, and roadside trees in Shanghai generates nearly 200,000 tons of green waste per year, while green spaces in units and residential areas generate approximately 150,000 tons per year, totaling around 350,000 tons, and this does not include forest areas. This means that in Shanghai alone, hundreds of thousands of tons of green waste that would otherwise require funding for disposal can be used as valuable raw materials for composting and soil improvement.
Additionally, there are also some more unexpected resources in the daily operation of cities.
Jing introduced that on the "Road to Tomorrow" visit to Weizhou Island, the owner of a coffee shop and bed-and-breakfast, A Liang, connected the air conditioner's drainage pipe to a water storage tank, collecting the condensate water generated by the air conditioner and reusing it to irrigate the garden. According to A Liang's estimate, this simple modification can save over 100 tons of water per year. For Weizhou Island, which has limited freshwater resources, the water that was originally discharged through the pipes during daily building operations is now part of a local recycling loop.
These seemingly fragmented small-loop practices can also be understood on a larger urban scale.
In 2021, a study published in Circular Economy and Sustainability took Vienna, with a population of approximately 1.92 million, as its subject to calculate the potential for nutrient recovery from domestic wastewater and degradable kitchen waste. The research model showed that if treated through methods such as artificial wetlands and anaerobic digestion, the wastewater and kitchen waste from 77,250 residents could theoretically recover enough nitrogen and phosphorus to meet the demand for these two fertilizers for all of Vienna's existing vegetable production. Currently, local vegetable production in Vienna can meet about one-third of the city's vegetable consumption demand.
This does not mean that sewage and kitchen waste can be directly used in agriculture. The nutrients in domestic sewage need to be purified, separated, and recycled, and kitchen waste also needs to be sorted and harmlessly treated to become safe and usable agricultural inputs. However, this calculation reveals a long-neglected aspect of urban food systems: food brings water and nutrients into cities, and after consumption, a considerable portion of them leaves the food production system with sewage and organic waste.
Kitchens, parks, roadside trees, and commercial spaces each generate different material flows, and when these paths are combined, a city presents a potential map of agricultural resources.
A type of urban waste having reuse value does not necessarily mean it is naturally a usable agricultural resource.
Before it can be reused, it needs to go through a series of steps including source classification, collection, transportation, sorting, processing, inspection, and utilization. If any one of these steps is missing, potential resources may once again become waste that can only be disposed of.
In cities, where dining, business, communities, and public spaces are highly concentrated, organic waste is constantly generated; gardens, green spaces, urban farms, and park systems that can digest these resources are also relatively concentrated, making short-distance circulation possible.
Distance is particularly crucial for organic waste. Branches and kitchen waste have a large volume, high water content, and limited economic value per unit, making transportation distance a direct factor affecting recycling costs. Jing believes that "local recycling is the most environmentally friendly" among various zero-waste practices. Community trimmings are crushed nearby, kitchen waste is composted locally, and the resulting fertilizer is used in surrounding gardens and green spaces, reducing garbage disposal and shortening the distance for resource reuse.
However, density can only be truly translated into an advantage when resources are effectively organized.
According to information released by the Shanghai Municipal Greening and City Appearance Management Bureau in 2026, Shanghai currently has around 90 units of green waste crushing machinery and approximately 95 disposal sites, but most of these sites still primarily rely on temporary storage, sorting, and crushing. In the central urban area, it is difficult to find stable spaces that can handle branch and leaf waste while controlling noise and odors; meanwhile, green waste generated by units and residential areas lacks unified collection channels, with some still being mixed into household garbage or discarded at will.
Costs have further influenced the choice of different treatment paths. The Shanghai Municipal Greening and City Appearance Management Bureau disclosed that the cost of resource-based treatment of green waste, such as composting, is approximately 250 to 300 yuan per ton, while biomass power generation can receive fiscal subsidies. This has led some maintenance companies to prefer transporting green waste to power plants in other provinces and cities, rather than producing organic media or cover materials locally. For individual companies, this is a lower-cost option; from the perspective of urban resource recycling, however, the organic matter is not being returned to the land where it was produced.
Solving this problem requires not only seeking a treatment technology, but also establishing a connection between the source and the user end.
In China, practices such as farmers' markets, community-supported agriculture (CSA), consumer cooperatives, and community stores have established various types of networks between urban consumers and surrounding agriculture. Chang Tianle, the founding editor of "Foodaily," a media outlet that has long focused on sustainable food and agriculture, and the organizer of the Beijing Organic Farmers' Market, told Fast Company China that many eco-friendly small farmers are using the municipal sanitation system to collect leaves, Chinese medicine residue, and other materials that were previously unusable to produce compost. The Beijing Organic Farmers' Market is also promoting household kitchen waste composting to consumers for use in community gardens and vegetable plots. Meanwhile, kitchen waste generated by the market's community store is taken back to farms by farmers who come to deliver produce, where it is composted.
Delivery vehicles travel from farms to cities and then bring organic waste from cities back to farms, essentially utilizing existing logistics to complete a round trip. This approach eliminates the need to establish a completely independent transportation route and fosters a relatively stable connection between the source and user ends.
Photo source: Xinhua Net
In 2001, the Food and Agriculture Organization (FAO) of the United Nations launched the Food for the Cities project, focusing on urban food supply in the context of rapid urbanization, as well as the connections between cities and their surrounding rural areas and agriculture. Based on this, the FAO and institutions such as the RUAF Foundation later developed the concept of "urban regional food systems," which encompasses cities and their surrounding suburbs and rural areas into a single food system, examining the entire process of food production, processing, transportation, consumption, and disposal.
In this framework, the connection between urban and rural areas is not just about farm products flowing from rural to urban areas, but also about the reverse flow of nutrients and organic resources: surplus food that is safe for consumption should be prioritized for redistribution, while organic waste that is no longer edible can be processed for energy and fertilizer production, serving urban and peri-urban agriculture.
However, most existing urban-rural networks were not built for waste recycling. The urban end requires workers to sort and store materials, transport demands extra space, and farms must invest in labor, equipment, and land to handle downstream processing. And due to issues such as contamination and mixed collection, not all organic waste is suitable for agricultural use.
Chang Tianle observed that without stable financial support and a clear cost-sharing mechanism, these efforts are either difficult to sustain or can only be carried out on a small scale by environmentally conscious individuals and organizations "working for love". The existing network can prove the possibility of return, but it is still not enough to automatically form a large-scale system.
To get these cycles out of their limited, spontaneous practices, it's essential to first clarify: Zero Waste does not mean that everything must be recycled.
Jing explained to Fast Company China that zero waste does not literally mean producing no garbage, but rather maximizing the continued use of items that still have value, thereby minimizing the amount that ultimately needs to be incinerated or landfilled. In China, a similar concept, "waste-free cities," is being explored. The Ministry of Ecology and Environment noted that "waste-free" does not mean that no solid waste is generated, but rather that the amount landfilled is minimized through source reduction and resource utilization.
From this perspective, garbage sorting is just the starting point of this cycle. To achieve a "waste-free city," it is also necessary to know, after sorting, where different residual materials are produced, how much of them there are, who collects them, where they are sent for processing, and ultimately who uses them. Only when these links can be sustained can a residual material possibly become a stable resource.
The Ministry of Housing and Urban-Rural Development proposed adopting a "decentralized processing + centralized processing" model in the pilot program for garden and green waste: in parks, green spaces, and nurseries where conditions permit, waste will be crushed and utilized on site; parts that cannot be disposed of on site will be transported to centralized facilities for processing via specialized vehicles. At the same time, categorized collection, storage, transportation, and processing facilities will be regarded as part of urban infrastructure, with the entire process managed digitally.
This model seeks to strike a balance between distance and scale. Over-concentration means longer transportation distances, while complete decentralization would result in a lack of equipment, space, and professional management at each processing point. A combination of small-scale collection and pre-processing facilities near the source, and large-scale processing facilities set up in areas with suitable space, may be a more realistic approach.
Shanghai is making similar attempts. According to information released by the Shanghai Municipal Greening and City Appearance Administration, Jing'an District built a green waste disposal point in Pengyupu Wedge Green Space in 2025, with a designed annual processing capacity of 2,880 tons. Branches and leaves are crushed and undergo preliminary processing here, with some being dried, sterilized, and made into ground cover particles, while others are sent to external districts, mixed with wet waste, and fermented to produce organic media.
According to calculations cited by the Liberation Daily, if the garden waste in Shanghai's central urban area can be processed locally, transportation costs are expected to decrease by about 50%. To further address the issue of insufficient space in the central urban area, Jing'an District has also incorporated road greening and maintenance units into a unified management platform, using vehicle positioning, weighbridge data, and data summarization to dispatch and collect waste.
By 2026, Shanghai has established around 10 "zero green waste discharge" demonstration sites. Century Park built an internal disposal point in 2023, and has basically achieved a situation where green waste within the park is no longer transported outside. Shanghai also plans to prioritize the use of locally sourced green waste to produce cover materials and organic media in land greening, ecological corridor, and park construction projects.
These efforts address the often-overlooked end of the cycle: not only must recyclable products be produced, but they must also be continuously used. If a city processes green waste on one hand, but still procures garden substrates from outside, the cycle will stall at the processing stage. The procurement and usage rules for public greening projects can establish a relatively stable demand for these products.
Practices in Fuzhou, Jiangxi also demonstrate the possibility of forming a closed loop within the public park system. Local reports show that the central urban area of Fuzhou generates around 3,000 tons of garden waste annually, which was previously mostly sent to a municipal waste incineration power plant. The city then built a facility for processing and utilizing garden waste, turning different types of branches and leaves into eco-friendly ground cover, organic fertilizer, or using them for seedling cultivation, and ultimately reusing them in urban parks and green spaces.
Another cycle occurs between enterprises, institutions and farms.
From March to April 2026, Kadoorie Farm and Botanic Garden in Hong Kong collaborated with 7-Eleven, Shin Yeh Group's Kinsen and WeGen farming to provide coffee grounds and their processed products generated by 7CAFÉ, a café chain under 7-Eleven, to local farms and gardens for free or at a low cost. The products included sifted coffee grounds, compost made from coffee grounds and garden waste, and further processed coffee enzymes.
According to data released by the Kadoorie Farm and Botanic Garden's official account, the first round of the project distributed 2.5 tons of coffee grounds and provided nearly 1 ton of coffee ground agricultural products. The second round is planned to continue from September to October 2026. Although the scale is still small compared to the amount of organic waste generated by a city every day, it demonstrates another mode of organization: retail stores provide a stable source of raw materials, public welfare organizations connect demand, professional institutions complete processing, and farms serve as the final user.
From self-sufficiency within public park systems to the establishment of reverse supply chains between enterprises and farms, various practices are filling in the gaps in urban resource circulation. They also illustrate that a system is not just a treatment plant or a recycling technology, but a set of operating mechanisms that simultaneously cover classification, collection, processing, inspection, use, and financial arrangements.
We are familiar with the route food takes to enter cities: starting from farmland, going through processing, transportation, and retail, and finally reaching consumers. For a long time, this route has been almost one-way - agriculture is responsible for production, cities are responsible for consumption, and what is left after consumption goes into the waste management system.
The reuse of urban organic waste is paving the way for a return route, but the return route will only be sustainable when classification, treatment, transportation, and utilization become stable mechanisms, rather than just a one-time composting activity or an eco-friendly project for a single store. At that point, the city will not only be the endpoint for agricultural resources, but also the starting point for the next round of production.