Suchergebnisse

AbstractThe growth in population and of the economy of Hong Kong has caused a significant increase in the demand for fresh water. To secure sufficient water supply and to reduce reliance on imported water from Dongjiang (East River) in Mainland China, the Hong Kong Special Administration Region (HKSAR) government has implemented a wide range of water conservation measures which include the use of seawater for toilet flushing, metering and a tiered water tariff, large‐scale replacement and rehabilitation of ageing pipelines to reduce leakage, valve‐type toilet flushing apparatus and education and publicity programmes. To ensure sustainable and safe water supply, the HKSAR government is actively exploring alternative water resources including the treated effluent from sewage treatment plant, desalination of seawater and the extension of water‐gathering grounds in the territory.

AbstractA systems analysis technique, called the 'analytic hierarchy process', has been employed to develop a wastewater treatment optimization model which enables consideration to be given to subjective factors such as socio‐cultural and environmental conditions as well as to technical and economic aspects. The model is particularly applicable to the developing world. Twenty and twenty‐two parameters were identified for the selection of wastewater and sludge‐treatment alternatives respectively. Forty‐six and ninety‐four treatment alternatives were formulated as decision variables for the selection for wastewater and sludge treatment respectively. The technique was then employed to select the optimum treatment procedures.

AbstractHong Kong is one of the very few coastal cities in the world that use 'dual water supply systems'. Dual water supply involves two distribution systems: a freshwater system for potable use and a seawater system for toilet flushing. This study looks into the feasibility, from an engineering cost point of view, of extending seawater supply into districts where potable water is still being used for toilet flushing, including South District of Hong Kong Island, Sai Kung, Northern New Territories and Northwest New Territories. Besides seawater, raw (untreated) freshwater and reclaimed water (treated effluent from local sewage treatment works) are also considered to be used for toilet flushing for these districts. Six cases are developed for comparison by using the lowest net present value of cost criterion. The result shows that using seawater for toilet flushing in these districts has the best engineering economy.