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Water Challenges in Modern Society
- Tai Lake(serious contamination)
- Droughts
- Water rationing has begun in Malaysia
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Sources of Potable Water-x
- Wells (underground water)
- Rainfall•
- Rivers
- Ice
- Desalination of sea water (Large desalination plant built in 1975 & decommissioned in 1981 due to high cost)
- Reservoirs: HK’s first: PokFu Lam Reservoir (capacity increase quickly)
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Hong Kong’s Water History-x
- Completion of Tai Lam Chung Reservoir
- Supply Agreement -Shenzhen Reservoir
- Severe Rationing
- Supply Agreement -Dongjiang68.2 mcm/year
- Completion of Plover Cove Reservoir, Completion of High Island Reservoir
- water rationing
- Supply Agreement -DongjiangMaximum 1,100 mcm/year
- 83-km closed aqueduct for protection of Dongjiangwater commissioned
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HK’s main water supply
- Local rainwater: 20% -30% of total water supply in Hong Kong
- The remaining 70% -80%: has to be imported from Dongjiang(DJ, “Eastern Rivers”) of Guangdong Province
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protection of water – Special aqueduct (closed) to protect DJ water from contamination when crossing the most industrialized regions, The water then goes through pipelines to…, Then crosses the border to …(木湖抽水站) of Hong Kong; in HK, protection measures include…
- Shenzhen Special Economic Region; Muk Wu Pumping Station
- Water gathering areas-> no development allowed
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Problems arising from dongjiang river for upstream areas
Unfair distribution of burden intra-basin economic disparity (under-developed upstream areas where development is restricted)
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HK water treatment plants location
Shatin, Sham Tseng
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Water supply process
- Pumping station, treatment plant, primary service reservoir, pumping station, service reservoirs, consumers
- DJ water, if not used, is stored in reservoirs
- Water treatment is done before primary service reservoirs
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Purpose of Pumping to service reservoirs
- Continuous supply
- Constant water pressure
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At consumers, for tall buildings (>10/F), water pumped to…, which is required to be cleaned every 3 months; key features
- storage tank on the roof by building management
- water pressure by gravity & lower water pressure at top floors due to smaller distance between the tank and the floor (less gravity)
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how to prevent disruption in water supply system
water path runs in paralleldisruption in one path doesn’t lead to outage
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is the DJ water order appropriate?
Yes, supply matches demand
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Main users of HK water
Hotels and restaurant, manufacturing sector
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How to conserve water
- Lower durationIR sensor on water tap and urinal
- Lower flow ratethe shower type washing taps, special showerheads, water efficiency labelling scheme, dual flush
- Eliminating the need
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water efficiency labelling scheme-what rating is the best
- 1
- Cubic meters to liter
- *1000
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Applications of rainwater collection systems, advantage and eg
- Cleaning; Water feature; Watering plants; Cooling towers; Toilet flushing
- Relatively low cost and easily implemented;
- Kowloon Commerce Centre; Millennium City; Villa by the Park; Ocean Shores
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Source of grey water (not too dirty water)
- Wash basins, Sinks (except kitchen)
- Showers, Baths
- Washing machine,
- Condensate from AC systems
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Use of sea water in HK
- Toilet flushing
- Free of charge, though cost covered via drinking water tariff
- Not available to some districts in NT and outlying islands
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Treatment of seawater
- not treated to the same standard as fresh water but still has to comply with guidelines laid down by Water Services Department
- Screened by strainers to remove sizeable particles
- Disinfected with chlorine or hypochlorite before being pumped to service reservoirs
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Cost of using seawater
- High construction & maintenance costs of seawater flushing facilities
- Related infrastructure such as pumping stations: also expensive
- Replacement of existing pipes to PVC (resistant to erosion caused by high salt content)
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Seawater supply system
Intake culvert (a pipeline), pumping station, treatment, service reservoirs
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