Behold the Sha Tin Sewage Treatment Works a place where waste transforms into a resource. Sha Tin Sewage Treatment Works stands as Hong Kong’s largest secondary sewage treatment facility. It serves 650000 people in Sha Tin and Ma On Shan. Let’s uncover the secrets held within the walls of Sha Tin Sewage Treatment Works.
Sha Tin Sewage Treatment Works occupies 28 hectares. This plant processes 260000 cubic meters of sewage daily. Commissioned in 1982, Sha Tin Sewage Treatment Works originally treated 100000 cubic meters per day. By 1986, its capacity increased to 200000 cubic meters daily.
In 1991, upgrades added nutrient removal. These upgrades improved Tolo Harbour’s marine environment. However, the treatment capacity temporarily decreased to 150000 cubic meters per day. The Stage III Extension began in 2001 to handle Sha Tin and Ma On Shan’s growing population. The capacity of Sha Tin Sewage Treatment Works increased to 340000 cubic meters per day after the extension was completed in 2011. An ultraviolet disinfection system was also installed to improve effluent quality.
Raw sewage undergoes primary sedimentation. About 50% of suspended solids settle. These solids are removed as primary sludge using scraping mechanisms. Next, secondary biological treatment occurs in aeration tanks. Compressed air feeds microorganisms. These microorganisms consume organic pollutants. The sewage remains in these aeration tanks for about 9 hours. Treated sewage and activated sludge then separate in final sedimentation tanks. Some activated sludge returns to the aeration tank. The remaining surplus activated sludge thickens before moving to sludge digesters.
The UV disinfection system treats sewage from final sedimentation. This ensures the effluent meets environmental standards. It further improves water quality in the discharge zone. Primary sludge and thickened surplus activated sludge pump into sludge digesters. Anaerobic digestion occurs. This process creates biogas containing methane a renewable energy source. Centrifuges then dewater digested sludge to at least 30% dryness. This reduces volume before transportation to the T.Park for incineration.
Sha Tin Sewage Treatment Works also reclaims water. Commissioned in 2011, the water reclamation facilities use disc filters. Ultra-filtration membranes and reverse osmosis membranes are used too. These generate 1000 cubic meters of reclaimed water daily. This reclaimed water is suitable for non-potable uses. It is used for plant cleaning, irrigation, toilet flushing and chemical dilution.
The Tolo Harbour Effluent Export Scheme helps prevent red tides. It moves treated effluent from Tai Po and Sha Tin Sewage Treatment Works to Victoria Harbour. This happens via a 7.4-kilometer tunnel and Kai Tak River. The water quality in Tolo Harbour has improved since the scheme’s implementation in 1998.
Beyond treatment, Sha Tin Sewage Treatment Works reduces energy consumption. It minimizes environmental impact. The plant uses combined heat and power generators. These generate electricity and heat using biogas from sludge treatment. De-odourisation units also improve the neighborhood’s living environment.
The government plans to relocate Sha Tin Sewage Treatment Works to caverns. Stage 1, including site preparation and access tunnel construction, began in 2019. It is targeted for completion in the fourth quarter of 2022. The entire project aims for completion by 2031. The relocated Sha Tin Sewage Treatment Works, named Sha Tin Cavern Sewage Treatment Works will be the largest of its kind in Hong Kong.
Sha Tin Sewage Treatment Works has an information center. It promotes public understanding of sewage treatment. It also raises environmental awareness. The center includes an exhibition gallery and lecture room. The exhibition gallery describes the Drainage Services Department’s work in flood control, sewage services, and sustainability. The lecture room explains the sewage treatment process before site visits. Sha Tin Sewage Treatment Works isn’t just a treatment plant. Sha Tin Sewage Treatment Works is a guardian of our environment. It is a testament to Hong Kong’s commitment to sustainability.