The sewage collected from the urban area around the harbour is treated at the Preliminary Treatment Works (PTWs) for the removal of large solids before conveying to Stonecutters Island Sewage Treatment Work (SCISTW) through the Sewage Conveyance System. Chemicals are added to the sewage for chemically enhanced primary treatment. The treated sewage is disinfected by chlorination and discharge to the sea after dechlorination. The sludge produced from the sewage treatment is dewatered and transported to sludge treatment facilities by marine vessels.
Schematic Design of Treatment Process
(Click to enlarge image)