Following is a question by the Hon Dennis Leung and a reply by the Secretary for Environment and Ecology, Mr Tse Chin-wan, in the Legislative Council today (July 2):
 
Question:
 
     It is learnt that the yard waste recycling centre Y·PARK mainly receives yard waste such as tree trunks that are six metres long or below, as well as branches, twigs and leaves. Regarding the handling of yard waste, will the Government inform this Council:
 
(1) as some members of the public have relayed that uncollected yard waste is often seen on streets and in parks, whether the Government has formulated guidelines requiring the Leisure and Cultural Services Department (LCSD), the Food and Environmental Hygiene Department (FEHD) and their outsourced contractors to first sort the collected yard waste and send the yard waste that can be processed by Y·PARK to the collection point of the Environmental Protection Department; if not, of the reasons for that;
 
(2) according to the existing procedures, how the LCSD, FEHD and their outsourced contractors handle yard waste that cannot be processed by Y·PARK; of the approximate tonnage of such yard waste in each year since 2019; and
 
(3) given that Y·PARK has imposed a number of restrictions on the recovery of yard waste, and it is learnt that some companies in the Mainland and the United States adopt anaerobic digestion technology to convert yard waste into biogas for electricity generation, whether the Government will consider adopting such technology to process yard waste, so as to enhance recycling and conversion of waste into energy; if not, of the reasons for that?
 
Reply:
 
President,

     The super typhoon Mangkhut that hit Hong Kong in 2018 caused severe damage, uprooting numerous trees, many of which were large trees that could be suitable for timber production. In 2021, the Environmental Protection Department (EPD) set up the temporary yard waste recycling centre, Y·PARK, in accordance with the Waste Blueprint for Hong Kong 2035, to collect and process yard waste generated from regular vegetation maintenance and public works projects, and to assist in treating large quantities of yard waste generated shortly after typhoons when needed.
 
     Yard waste includes grass, leaves, shrubs, twigs and woody tree trunks. Some of them may be affected by pests or diseases. Y·PARK mainly collects and sorts out the high quality and suitable portion of yard waste for recycling into recyclable products of relatively higher values so as to achieve both converting waste to resources and enhancing cost-effectiveness.
 
     The current Y·PARK is temporary in nature. In future, the Government reserves land in the New Territories North New Town to develop a larger-scale yard waste recycling facility to enhance yard waste handling capacity. 
 
     Having consulted the Food and Environmental Hygiene Department (FEHD) and the Leisure and Cultural Services Department (LCSD), our consolidated reply to the question raised by the Hon Dennis Leung is as follows:
 
(1) The Government has established guidelines to drive various government departments, including the FEHD and the LCSD, adhering to the principles of reduce, reuse, and recycle, to shred and reuse yard waste as much for gardening on-site as far as possible, while yard waste that cannot be treated or reused on-site could be delivered to suitable recycling facilities for treatment. The EPD has also continuously liaised with government departments, providing relevant guidelines to promote the proper sorting of recyclable yard waste at source and its delivery to Y·PARK for processing. In 2024, the quantity of yard waste disposed of at landfills was about 230 tonnes per day, accounting for about 2 per cent of the municipal solid waste (MSW) disposal of at landfills.
 
(2) Not all yard waste is suitable for delivering to Y·PARK for processing. According to prevailing handling procedures, when the FEHD, the LCSD and their contractors encounter yard waste unsuitable for recycling, such as yard waste infected by bacteria, infested with pests, or containing large amount of impurities, while providing street cleansing or park management services, such yard waste will be sent directly or via refuse transfer stations to landfills for disposal. From 2019 to April 2025, the LCSD transported an average of about seven tonnes of yard waste unsuitable for recycling to landfills per day, whilst the FEHD does not maintain relevant data.
 
(3) The Government is developing two main types of waste-to-energy facilities currently. The first type of facilities is the Organic Resources Recovery Centre (O·PARK), adopting anaerobic digestion technology to process food waste. The second type of facilities adopts modern incineration technology to treat waste, such as T·PARK which incinerates sludge to generate electricity, and the Integrated Waste Management Facilities Phase I (I·PARK1) under construction which will incinerate MSW to generate electricity.
 
     The O·PARKs are designed to treat food waste which contains proteins, sugars, fats and high water content. These substances decompose more easily during anaerobic digestion process, and produce more biogas, resulting in a higher energy conversion efficiency for electricity generation. Under feasible technical conditions, we also make the best use of the existing waste management facilities to test out the treatment of other waste. For instance, while O·PARK2 is mainly for treating food waste, we conducted trials for treating pig waste by anaerobic digestion since its commissioning in March 2024. Following the successful trials, we have fully replaced the previous practice of disposing pig waste at landfills with anaerobic digestion technology since July 2024, which significantly reduced the potential odour issues associated with disposal of pig waste at landfills.
 
     However, there are significant differences between yard waste and food waste. It requires different treatment methods for yard waste. Yard waste comprises woody waste, such as tree trunks and branches, as well as non-woody waste, such as leaves and grass.  Tree trunks and branches are high in wood fiber content and low in moisture content, so they are not easily decomposed by anaerobic digestion. If treating the yard waste by co-digestion by anaerobic digestion technology in O.PARKs, it would not only occupy substantial space in the digestion tanks but would also significantly reduce food waste processing capacity and efficiency. In addition, as woody waste is hard and bulky, it is more difficult to be crushed into pieces as compared with food waste, such that additional energy and water will be required to turn the woody waste into slurry for further treatment. The installation of necessary pre-treatment facilities in O·PARKs and modifications to the existing operation mode will incur a substantial amount of cost but result in low energy efficiency. According to the understanding of the EPD, there are few examples of utilising anaerobic digestion technology to process woody waste in the Mainland or overseas. Even for such cases, they mainly involve processing small amount of non-woody yard waste such as grass and leaves.
 
     Non-woody garden waste such as grass and leaves can be processed through anaerobic digestion technically, but the process would be less efficient than treating food waste. Considering that such waste contains a certain calorific value and is often mixed with other MSW during collection, treating yard waste by incineration can reduce the need for additional space, processing, and costs associated with sorting yard waste from mixed waste while achieving the same outcome of turning waste into energy. The Government is working full steam on developing two modern large-scale incineration facilities, namely I·PARK1 and I·PARK2. These facilities will handle up to 9 000 tonnes of MSW per day in total in the future, converting waste into electricity. I·PARK1 is expected to commence operation by the end of this year and can assist in handling yard waste.

     Thank you, President.

Ends/Wednesday, July 2, 2025
Issued at HKT 15:35

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