Much lower emissions of microplastics and nearshore water levels in Hong Kong than other regions
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To better understand the situation of microplastic emissions from the sewage treatment systems into the marine environment, the EPD and the Drainage Services Department commissioned the City University of Hong Kong in 2019 and 2020, respectively, to study the microplastic abundance in Hong Kong's nearshore waters. The latest findings of the study revealed that the current microplastic level in Hong Kong's nearshore waters is about 90 per cent lower if compared with other developed places.
An EPD spokesman said that the study results also suggested that the sewage treatment works (STWs) in Hong Kong have relatively high microplastic removal efficiency as compared to similar facilities in the world. Among them, STWs using chemically enhanced primary treatment processes can remove about 80 per cent of microplastics in sewage, with six microplastic particles per litre in sewage effluent; for STWs using secondary biological treatment processes, about 90 per cent of microplastics can be removed, with four to five microplastic particles per litre in sewage effluent. These values are much lower than the average value of STWs (i.e. about 30 microplastic particles per litre in sewage effluent) in other large cities globally.
Currently, 93 per cent of the population in Hong Kong is covered by the public sewerage system, which is considered a very high level around the world. Sewage from the remaining seven per cent of the population is treated by private STWs or septic tanks; since the sludge generated from the septic tanks would be transferred to public STWs for further treatment, most of the microplastics in sewage can be removed through treatment, and the amount of microplastics finally finding their way into Hong Kong waters would also be remarkably reduced. This observation echoes the aforementioned study findings that the current microplastic abundance in Hong Kong's nearshore waters is lower than that in other regions.
The EPD has been dedicated to focusing the environmental issues arising from waste plastics and microplastics, striving to promote a plastic-free culture and to protect the marine environment from plastic pollution. The EPD launched the Bye Bye Microbeads charter in September 2021, encouraging the trade to immediately eliminate rinse-off products containing microbeads, while assisting consumers in choosing microbead-free products, with a view to reducing the potential risk of microbeads at source for the marine ecosystem.
The spokesman said, "Currently, the implementation of the charter has achieved remarkable outcomes. As of the end of December this year, more than 160 organisations have joined the charter, covering nearly 140 brands. The EPD also examined more than 9 000 rinse-off personal care and cosmetic products through a market survey, and found no products containing microbeads."
The spokesman further highlighted that single-use plastic wastes in daily life are one of the major sources of microplastics. The Government has been striving to promote the plastic-free and waste reduction culture for all, through legislation to reduce the use of plastic bags, plastic bottles and disposable plastic tableware to reduce the flow of plastic wastes into the marine environment.
The EPD also noted that Europe and the United States are exploring different ways to reduce microfibre release during laundry, including the installation of microfibre filters in washing machines. As filters with excessively small pore sizes are prone to blockage, and those large-size microplastics can already be removed through sewage treatment, there is still a lack of mainstream options widely acceptable internationally. In addition, the aforementioned study has already pointed out that the microplastics found in the sewage effluent in STWs are mainly small-size particles (0.02 - 0.3 millimetres), therefore installing microfibre filters may not be the most effective solution to reduce those microplastics in the size range of concern. Nevertheless, the EPD shall keep in view the developments and evaluate feasible solutions and measures having regard to the local situation.
Ends/Friday, December 30, 2022
Issued at HKT 19:00
Issued at HKT 19:00
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