Q&A: Urban Yard Waste in Hong Kong

2022-04-29

| Dr. Law Man Yee, Caroline - Assistant Professor, Department of Environment Faculty of Design and Environment, THEi

1. What is the problem with disposing yard waste in landfills?

Our urban forests provide many ecosystem services. However, when dead plants are disposed of at landfills as yard waste, it does not just take up resources and occupy landfill spaces. They also generate landfill gases, like methane and carbon dioxide.

According to the "Monitoring of Solid Waste in Hong Kong Waste Statistics for 2020 Report” published by the Environmental Protection Department (EPD), food waste, paper waste and plastic waste (30%, 24% and 21% respectively) accounted for the majority of waste disposed of at landfills in Hong Kong. Yard waste only accounted for 2.1% (222 tons per day) [1].

Yard waste contributed merely 2.1% to Hong Kong’s solid municipal waste. It sounds that it was just a scant quantity. But it does not mean that we can continue to dispose these biodegradable materials in landfills. It is our top priority to understand and address the root of the problem. In the last ten years, the recycling rate of yard waste in Hong Kong was less than 3% (2,000 tons). There is a large room for improvement (60,000 to 70,000 tons was disposed of at landfills each year in recent decade).

2. What are the developments in recent years?

EPD set up a Yard Waste Recycling Centre (Y·PARK) at Tsang Tsui, Tuen Mun, which commissioned on June 2021. Y·PARK converts wood waste into usable materials, such as compost, biochar or for upcycling. Y·PARK does not receive grass clippings, leaves and small branches (except those attached on tree trunk).
The government is currently funding educational institutions and industries to promote environmental protection projects. For instance, the THEi Bachelor of Science (Hons) in Horticulture, Arboriculture and Landscape Management Programme received funding support from the Environment and Conservation Fund in November 2019 to promote the "ECF Yard Waste – Pilot Scheme for Private Housing Estates" and encourage the society to start yard waste recycling. The pilot provided equipment for three private housing estates in Hong Kong, along with technical support, to help the horticultural and property management staff make compost from their yard waste and facilitate sustainable yard waste management. This project also offered online workshops to educate the public.

3. What are the reasons/difficulties for the low recycling rate of yard waste in Hong Kong?

Landscape and property management industry and the public rarely have the relevant knowledge and expertise. They have limited knowledge on proper disposal of yard waste, and they are not familiar with "onsite composting” or lack of equipment like shredders and compost bins.
Most of the grass clippings, leaves and small branches produced by green space maintenance are transported to adjacent landfills for disposal, and there is a lack of incentive to change such practices.
When local arborists cut down urban trees, twigs and leaves are separated for ease of transportation. However, detached twigs and leaves are not accepted by Y·PARK. To avoid doubling transportation costs, these twigs and leaves, along with the large trunk, will be disposed of at nearby landfills.

4. What is the way out for yard waste?

Although the government only has one remote yard waste recycling centre at present, "on-site composting” to reduce waste at source is essential before the implementation of the waste charging scheme. What’s more, Y·PARK currently does not accept grass clippings, leaves or small branches.
All sectors should compost their own yard waste, such as grass clippings, leaves and small branches, as much as possible.
Larger and high-quality trunks can be upcycled into woodcraft, furniture, and more.
Lower quality wood waste and chippings can be made into various products, such as compost, wood chip and biochar. A variety of by-products can be made, such as deodorant products, filtering products, and construction and decoration materials.

5. What urban settings are suitable for "on-site composting”?

Housing estates, shopping malls, schools and other venues with green space in Hong Kong can consider "on-site composting”, based on available space and resources.

6. What are the considerations to start "on-site composting”? Is it cost-effective?

The following considerations are applicable for small and medium-sized venues in urban areas. Large-scale venues will require more investment.

Equipment: In order to process smaller tree branches (<4 cm diameter), an electric shredder is a suitable choice for small and medium-sized housing complexes. Three compost bins and an electric shredder cost around HK$4,000. In the survey for the pilot, more than 70% of respondents believe that this is an acceptable price, and that the equipment will last for many years.

Space: Property managers usually want to reduce the impact of compost bins/composting process on the surrounding landscape and will select inconspicuous spaces to place them. As three compost bins take up limited space (less than one square meter each), it is not difficult to find a space for them, even including the workspace reserved for composting needs. If there is a lot of yard waste, there is a need to increase the number of compost bins.

Manpower and Expertise: Normally, a property management staff member can be deployed in charge of supervising the on-site composting process, supported by two front-line workers (one responsible, the other supporting). In the early stages, it would be ideal to find a person experienced in this field to monitor the progress and provide regular guidance. In the survey, respondents generally agreed that manpower input of two to three hours per week is acceptable.

Hygiene: As long as the plant material ratio and moisture amount is properly controlled and air circulation is maintained, on-site composting generally will not lead to any hygienic problems. The housing complexes that participated in the pilot mentioned that composting did not bring about adverse environmental impacts to them.

If you want to know more, please view the programme summary

7. How to produce compost?

Please refer to the video and booklet below:

Online classroom – How to make yard waste compost

https://youtube.com/playlist?list=PLVyv6SMY6fzv5288CX88v9qj4QZ0RGvyz

Download [A guide to on-site composting of yard waste at housing estates] (Chinese only)

8. How can various sectors promote yard waste reduction and recycling?

The government can subsidize more venues to purchase equipment and also the course fee to support relevant personnel to participate in on-site composting courses.
Participation from different sectors of the society is essential. Through practicing on-site composting, the private sector, such as residential and commercial buildings, can enhance interaction between property management/shopping malls and residents/customers and ESG performance. NGOs and educational institutions can organize courses, workshops and neighbourhood collaboration to realize yard waste management and compost production.
As for the government, contractors for government greening maintenance contracts should be required mandatory to make "on-site composting” using grass clippings, leaves, and small branches (except medium and large branches), subject to site conditions. It can be done step-by-step at the beginning of the implementation process.
The arboricultural industry can set up their own wood chipping and composting equipment at their depots/nurseries, where site conditions allow.
Wood crafting companies, landscape and horticultural companies, and NGOs can cooperate to apply for grants or funds to establish an online matching platform to connect wood log donors and users, preferably within the same district to reduce transportation process. The matching platform can play a coordinating role for the sorting and upcycling of large or high-quality timber.