Transcript Water pollution - Department of Geography

Water pollution
A case of Hong Kong
Water conditions in
HK
• Beach water quality
• Marine water quality
• River water quality
Can you think of some impacts of
water pollution?
• Make swimmer sick
• Kill marine life
• Give off bad smell
Impact of water pollution
• Red tides are blooms of
microscopic algae which
produce a characteristic pink
or reddish-brown colouration
in seawater.
• Red tides reduce sunlight
penetration, and at night or
when the algae die, deplete
DO in the water.
• Some species may also release
toxic substances. Red tides can
cause massive fish kills in
marine fish culture zones
through removal of DO or
direct poisoning.
Beach water
quality
• All very poor beaches
are found in Tsuen
Wan area
Annual ranking system for
beaches
Rank
E. coli count per Minor illness
100mL*
rate**
(Cases per 1000
swimmers)
WQO
Compliance
Good
< 24
undetectable
Complied
Fair
25 – 180
< 10
Complied
Poor
181 - 610
11 to 15
Not complied
Very Poor
> 610
>15
Not complied
*Geometric mean E. coli count calculated based on all the data collected during the
bathing season.
** Gastrointestinal and skin complaints
Beach monitoring programme
• to assess compliance with the Water Quality
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Objective;
to detect any change in beach water quality;
to identify polluted beaches that need remedial
actions;
to evaluate pollution abatement programmes;
to decide on the opening of beaches; and
to advise the public on the beach water quality
status.
Marine water quality
• Hong Kong is divided into 10 Water Control Zones
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(WCZs) and each WCZ has a set of Water Quality
Objectives (WQOs).
Dissolved Oxygen (depth-average)  Not less than
4mg/L in 90% of the samples
Dissolved Oxygen (bottom)  Not less than 2mg/L in 90%
of the samples
Unionized Ammonia Annual mean  not exceeding
0.021mg/L
Total Inorganic Nitrogen Ranging from annual mean 
not exceeding 0.1mg/L in Southern Water Control Zone to
not exceeding 0.7mg/L in Deep Bay Water Control Zone
E.coli Annual geometric mean  not exceeding
610/100mL in secondary contact recreational areas
Black spots of marine pollution
Water pollution in PRD
estuary due to intensive
industrial development
Sometimes, you can "see"
water pollution like the
discharge of coloured
bleaching and dyeing
wastewater into a nullah as
shown in the photo.
Most typhoon shelters receive substantial pollution loadings from
storm stormwater drains which receive raw sewage and industrial
effluent via improper connections. Some discharges are from
vessels themselves. Some vessel users also dump garbage into
the water. As water movement is confined in a typhoon shelter,
pollutants cannot be flushed out easily , thus exacerbating the
pollution problems.
Oyster farms at the Deep Bay
are abandoned due to serious
water pollution and the decline
of importance in oyster farming
This photo shows the coloured
water of Rambler Channel caused
in the past by the discharge of
bleaching and dyeing effluent into
the sea.
Poultry waste from the farms
nearby caused eutrophication in a
stream (Tai Tong)
River water quality
• EPD regularly monitors water quality at more than 80
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sampling stations in over 30 rivers and streams in the
territory.
In situ field measurements are performed and water
samples are collected for further laboratory analyses
mostly on a monthly basis.
The monitoring covers more than 40 parameters
including physico-chemical characteristics, organics,
nutrients, toxic metals and coliform bacteria.
The rates of annual compliance with the statutory WQOs
are assessed based on the data obtained during the year.
Water Quality Index (WQI) for
Rivers
• based on the level of dissolved oxygen, 5day Biochemical Oxygen Demand and
ammonia-nitrogen
Improvements arising from enforcing
the Water Pollution Control Ordinance
Regions
Before control
(kg BOD/day)
At end of 2005
(kg BOD/day)
Percentage
reduction
Eastern New
Territories
(sum of 7 rivers)
13,365
2,566
81%
Northwestern New
Territories
(sum of 11 rivers)
20,095
3,990
80%
15
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100%
Southwestern New
Territories and
Kowloon
(sum of 4 rivers)
7,204
511
93%
Total (23 rivers)
40,679
7,067
83%
Lantau Island
(Mui Wo River)
The Livestock Waste Control
Scheme
• introduced in 1987 and further revised in 1994.
• designated a series of Prohibition Areas in which the keeping of
livestock was completely banned after 24 June 1988.
• Farmers outside the Prohibition Areas were permitted to continue
rearing livestock, but they were required to properly dispose of their
waste and treat their effluent
• technical help:
– publishing a code of practice and guidelines on waste treatment options
– setting up a private farm demonstration treatment plant.
• established a free livestock waste collection service
• made financial help available for farmers to install their own waste
treatment facilities.
• provided incentives for farmers for whom the new system was too
difficult: it offered eligible farmers an ex gratia allowance if they chose
to close down their livestock business completely.
Government policies –
three-pronged approach
• Controlling at source
• Providing sewers
• Collecting and treating sewage
Controlling at source
• Water Pollution
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Control Ordinance
Specifications of
meeting standards are
contained in licences
Implementation by
regular inspections,
response to
complaints and
prosecutions
Proving sewers
• Extend public sewer
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networks in NT and
new development
areas
It prepares sewerage
masterplans and the
works are carried by
Drainage Services
Department
Collecting and treating sewage
Storm Water and
Sewage Collection
Sewage treatment plant in Shatin
Procedures of treating waste water
HATS
• Harbour Area Treatment
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Scheme
Stage 1: sewage from
Kowloon and part of HK
 Stonecutters Island
Sewage Treatment Works
(SISTW) for chemical
treatment (late 2001)
Stage 2: sewage from N
& SW HK island  SISTW
for chemical treatment
(2A) and biological
treatment (2B)
Implementation of HATS
• Whilst Government will shoulder the cost
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of constructing Stage 2, the full operating
costs will have to be recovered through
sewage charges.
The public consultation demonstrated that
the majority of respondents support this
application of the "polluter pays"
principle.
With the introduction of the sewage
charge, dischargers are required to pay the
cost of the sewage services according to
the quality and quantity of their
discharge.
Domestic Households
The only charge is the Sewage Charge
(SC) at a prescribed rate of $1.20 per cubic
metre of water consumed, with exemption
for the first 12 cubic metres, in a fourmonth billing period.
Trade, Business and Manufacture
The charges include a Trade Effluent
Surcharge (TES)
Improvements made
• No. of beaches meeting Water Quality Objective for
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bathing water increased from 24 in 1995 to 34 in 2005.
No. of river monitoring stations with bad or very bad
water quality dropped from 52% in 1988 to less than
15% in recent years.
Toxic metal discharges reduced from 7,000 kg/day in
1993 to 2,000 kg/day in 2000
75% of sewage around Victoria Harbour receives
chemical treatment due to HATS
Dissolved oxygen in harbour waters increased by 10%
Drop in red tides in Tolo Harbour from 43 in 1988 to less
than 20 in recent years
Regional issues
• Regional cooperation with Guangdong
Government
• 15-year-plan to clean up Deep Bay
• In mid-2003, a regional water quality
management strategy was formulated