Overview of Sewage Treatment and Sewerage System in 2018-19

Apart from stormwater drainage, one of the core services of the Department is to collect, treat and discharge sewage generated daily in Hong Kong. DSD is committed to providing world-class sewage treatment services through adopting various sewage treatment processes and advanced technologies to significantly reduce the discharge of pollutants. We also carry out regular repair and maintenance works to ensure the effective operation of our sewerage, treatment and disposal facilities. Looking ahead, we will continue to expand the coverage of the sewerage system and to improve the sewage treatment facilities to protect the water quality within Hong Kong waters and promote the sustainable development of Hong Kong.

Currently, we are operating 319 sewage treatment facilities, including 69 sewage treatment works (STWs) and 250 sewage pumping stations (SPSs). In 2018-19, we treated 1,028 million cubic metres of sewage in total, of which 7.3% underwent preliminary treatment, 73.0% chemically enhanced primary treatment (CEPT), and 19.1% secondary treatments. The remaining 0.6% underwent primary and tertiary treatments.

Hong Kong-Zhuhai-Macao Bridge Hong Kong Port Sewage Treatment Works

Hong Kong Boundary Crossing Facilities (HKBCF) is located on the artificial island at the east side of the Hong Kong International Airport. To treat the sewage produced from the passenger clearance building, public toilets and government offices, a secondary sewage treatment works was built on the artificial island and was commissioned in September 2018. The design capacity of the plant is about 2,700 cubic metres per day and the plant adopts the membrane bio-reactor (MBR) technology for sewage treatment. Sewage first passes through 25 millimetres, 6 millimetres and 2 millimetres screens. Then, organic matters, suspended solids, ammonia-nitrogen, nitrate and nitrite-nitrogen are removed from sewage by the MBR. Lastly, effluent is filtered by flat-sheet membranes. Sludge produced during sewage treatment is transported to Siu Ho Wan STW for further treatment.

Our Department continues to maintain an efficient and effective operation with regard to sewage collection, treatment and disposal. At the same time, we ensure that our facilities meet with the set environmental protection objectives. Our team of professionals, aided by advanced technology and modern facilities, is working towards providing and delivering world-class sewage collection and treatment services for Hong Kong.

Hong Kong-Zhuhai-Macao Bridge Hong Kong Port STW

Professional Laboratory Services

Professional laboratory services are imperative in ensuring treated sewage meets the statutory requirements. DSD operates a number of laboratories to provide various types of testing services. Since 1999, our Sha Tin Central Laboratory and Stonecutters Island Laboratory have been accredited for testing environmental samples (water & wastewater) under the Hong Kong Laboratory Accreditation Scheme (HOKLAS) operated by the Hong Kong Accreditation Service of the Innovation and Technology Commission (ITC). The Stonecutters Island Laboratory has also gained a chemical testing accreditation which has allowed the analysis of the main components of chemicals applied in sewage treatment since 2007. To enhance laboratory efficiency and reduce human error, automatic analysers for nutrient tests, heavy metal tests and biochemical oxygen demand (BOD) tests have been installed in the Sha Tin Central Laboratory. HOKLAS accreditation of BOD tests using automatic BOD analyzers was obtained in 2017 and the Sha Tin Central Laboratory was the first laboratory in Hong Kong to grant the accreditation in this aspect.

The adoption of the Laboratory Information Management System (LIMS) and business intelligence software, not only helps us automate laboratory work flow, but also facilitates computerised management. The consolidation of laboratory results and operation data can assist us to monitor effluent quality, facilitate effective decision making, and control the sewage treatment process.

Laboratory Information Management System and Business Intelligence Software

Sha Tin Central Laboratory

To improve the precision of instruments, monitor water quality in meeting specified discharge requirements and the efficiency of the sewage treatment process, we carry out regular sewage sampling and analyses. During the year, 32 of our laboratory test items were accredited and more than 260,000 analyses were conducted. The analytical results of effluent quality of major sewage treatment works can be found on our website.