dr. bui xuan thanh - geo€¦ · 31,000 ha of rice fields, upland gardens, fruit orchards &...
TRANSCRIPT
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Dr. BUI Xuan Thanh
Associate Professor
Faculty of Environment & Natural Resources
Ho Chi Minh City University of Technology Email: [email protected] (+84 965 37 6073)
Taipei - Taiwan
International Conference on Forward-looking Water Management November 8-9, 2018
Organized by
Water Resources Agency, MOEA, Taiwan
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CONTENT
General Information 1
Water Pollution in Viet Nam 2
Solutions 3
Conclusions 4
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Two biggest deltas in Vietnam:
• 68.4% of country rice cultivated
areas
• 71.3% of rice quantity
GENERAL INFORMATION
Vietnam Delta (Wikipedia)
Red River Delta:
Population: 19999 people
Total area: 21068 km2
Density: 949 people/km2
Mekong Delta:
Population: 17331 people
Total area: 40548 km2
Density: 427 people/km2
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VIETNAM WATER MARKET
In the next 5 years, the demand for
water sector investment
10 billion USD
Investment demand (Statistics Ministry of Construction, 2018)
Water Supply
3.3 billion USD Water Drainage
6.9 billion USD
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VIETNAM WATER MARKET
Water Supply (Vietnam Environment Administration Journal)
• 100 enterprises manage ~ 500 large & small water
supply systems in urban centers nationwide.
• Total water supply capacity: 7 million m3/day
Price: Vary with locations & water resources (1$ =23,000 VND
Location Company Price (VND/m3)
Ha Noi Hanoi Water Ltd. Co. (HAWACO) 5,973
Ho Chi Minh Sai Gon Water Supply Corp. (SAWACO) 5,300
Binh Duong Binh Duong Water Environment JSC. (BIWASE) 8,500
Da Nang Da Nang Water Supply JSC. (DAWACO) 3,809
Tuyen Quang Tuyen Quang Water Supply & Sewerage JSC 4,500 – 5,500
Industry/Services Most of industries/services 12,000
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VIETNAM WATER MARKET
Profit:
• Saigon Water Corp. (SAWACO): subsidy
• PHUWACO water supply JSC: Net profit ~ 6.53% in 2012. (after 5 years)
• Ben Thanh WASUCO JSC: Net profit ~ 3.3% in 2017.
• Dong Nai Plastic Corp. (Just invest in Water Sector in 2017):
Revenue ~ 70 billion VND & Net Profit ~ 5 billion VND.
Water Sector in Vietnam:
• Steady growth & good profits
• Lots of attention.
(Doanh nhan Sai Gon, 10/7/2018)
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WATER SUPPLY - HCMC
Others(Private
company)
Tan PhuWTP
Kenh DongWTP
Tan HiepWTP
BOO ThuDuc WTP
BOT Binh AnWTP
Thu DucWTP
Ground water Surface water Sai Gon River
Surface water Dong Nai River
75,000 m3/day (5%) 1,445,000 m3/day (95%)
Water Production and Distribution of SAWACO
(SAWACO, 2014)
Water supply planning until 2025 (Prime Minister Decision 729/QĐ-TTg)
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Surface Water
Issues
9 9
Saigon river water quality is being deteriorated with time, increase in organic & ammonia pollution (Dan et al., 2013)
COD, DOC > standard limit for water supply purpose
ORGANIC POLLUTION In SAIGON RIVER
Variation of COD & DOC along Saigon river:
From Dau Tieng lake to Downstream (km)
10 10
(Dan et al., 2013)
Ammonia > Standard limit for water supply purpose (QCVN 08-MT:2015/BTNMT: NH4-N < 0.3 mg/L)
NUTRIENT POLLUTION In SAIGON RIVER
Variation of TKN & Ammonia along Saigon river: From Dau Tieng lake to Downstream (km)
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SAIGON WATER QUALITY: Hoa Phu STATION (SAWACO, 2016)
Parameter Unit 2011 2012 2013 2014 2015
pH - 6.17 ± 0.37 6.22 ± 0.13 6.33 ± 0.23 7.07 ± 0.06 7.12 ± 0.06
Color Pt-Co 288 ± 114 256 ± 113 189 ± 59 291 ± 147 280 ± 162
Turbidity NTU 41 ± 17 35 ± 17 25 ± 10 40 ± 19 44 ± 19
Alkalinity mg/L 17 ± 4 17 ± 2 16 ± 3 25 ± 4 25 ± 3
SS mg/L 31 ± 18 26 ± 9 21 ± 10 35 ± 18 33 ± 12
Ammonia mg/L 0.47 ± 0.24 0.33 ± 0.18 0.34 ± 0.18 0.24 ± 0.05 0.20 ± 0.09
Nitrite mg/L 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.01 0.01 ± 0.02
Nitrate mg/L 0.50 ± 0.20 0.58 ± 0.16 0.35 ± 0.13 0.62 ± 0.27 0.98 ± 0.15
Fe mg/L 1.05 ± 0.22 0.95 ± 0.21 0.76 ± 0.16 0.96 ± 0.24 0.81 ± 0.18
Mn mg/L 0.13 ± 0.04 0.13 ± 0.05 0.10 ± 0.02 0.15 ± 0.09 0.13 ± 0.06
BOD5 mg/L 4.6 ± 1.2 4.9 ± 1.0 4.2 ± 0.6 2.3 ± 0.7 2.2 ± 0.7
COD mg/L 12.0 ± 0.9 11.2 ± 1.1 10.8 ± 1.1 11.3 ± 1.5 10.8 ± 1.5
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Reservoir Sand
filtration
Sedimentation
tank Mixing tank
Chlorine
Pump
Station River Receiving tank
Distribution
network
Chlorine
Chlorine Alum/PACl
SURFACE WATER TREATMENT TECHNOLOGY
Conventional treatment
technology & use high
chlorine dosage!!!
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Chlorine is widely used for disinfection & pre-chlorination in WTP DBPs.
DBPs in drinking water serious problem to human health
SECONDARY POLLUTION: THMs
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0.0
1.0
2.0
3.0
4.0
5.0
1 2 3 4 5 6 7 8 9 10 11 12
Ch
lori
ne
(g
/m3)
Month
Dosing Dose
(g/m3)
Chlorine demand (kg/day)
min max Average
At pump station 1 – 2 300 600 450
At receiving tank 2 – 4 600 1.200 900
At clean water
storage tank
0.3 – 0.5 90 150 120
Before pumping to
pipe system
0.5 – 1.0 150 300 225
Total 1140 2250 1695
Chlorine (3-4 mg/L) dose used at Hoa
Phu pump station for pre-chlorination (SAWACO, 2016)
Chlorine dose at Tan Hiep WTP (SAWACO, 2013)
CHLORINE DOSAGE
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TOC reached threshold (4 mg/L) of QCVN 08-MT:2015/BTNMT; TOC is mainly in dissolved form as DOC not removed by
coagulation & filtration; THMFP of raw water at Hoa Phu intake was high (380-420 μg/L)
0
20
40
60
80
100
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr
DO
C/T
OC
(%
)
DO
C, P
OC
(m
g/L)
POC DOC DOC/TOC
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0
100
200
300
400
500
TOC
(m
g/L)
THM
FP (
g/L)
Month THMFP TOC
ORGANIC & DBPs MONITORING (Dan et al., 2016)
THM standard
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0
100
200
300
400
500
concentration
(ug/L)
TotalTHMInternationalStandards
THM Standard Limits in Different Countries
Vietnam Standards: (TTHM: 460 μg/L)
QCVN 01/2009 Ministry of Health
- CHCl3: 200 μg/L
- CHCl2Br: 60 μg/L
- CHClBr2: 100 μg/L
- CHBr3: 100 μg/L
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Compact Surface WTP in Long An province (built by SAWACO)
SURFACE WATER TREATMENT PLANT
Sedimentation tank in Thu Duc WTP
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Technology limits:
• Conventional water treatment (large footprint)
• Effective removal of turbidity, SS, colloids.
• Ineffective to remove TOC & micro pollutants
(EDC, PhCPs, Pesticides,...)
• Use Chlorine as disinfectant THMs formation
• Tap water is not drinkable like in Japan/Europe!
TECHNOLOGY EVALUATION
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Groundwater
Issues
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Arsenic contamination:
+ As = 1 - 46.9 g/L (Long An province)
+ As > 100 g/L (Dong Thap. An Giang
provinces near Cambodia)
(WHO, QCVN 01/BYT ~ 10 g/L for
drinking water) (Thanh et al., 2011)
Map of well distribution & water
exploitation reserve in MD provinces
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(Khanh et al., 2013)
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High As conc. was found at the well with depth of 200-300 m. [16 samples in Long An province exceed the WHO’s standard, 10 ppb] (Thanh et al., 2011)
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Sand
filtration
Sedimentation
tank Mixing tank Pump
Station Tray aeration
Distribution
network Reservoir
Chlorine
Ground
water
Lime
Chlorine
HCMC:
Air contact + sand filtration Aeration tray + sand filtration
GROUNDWATER TREATMENT TECHNOLOGY
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Technology limits:
• Conventional treatment technology (aeration + filtration)
• Effective removal of Fe/Mn, SS.
• Ineffective removal: Ammonia, Arsenic, TOC &
micro pollutants.
• Use of Chlorine as disinfectant (low dosage in MD provinces)
THMs formation.
TECHNOLOGY EVALUATION
• Can not remove Salt from water Need of novel tech.
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Saltwater Intrusion
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• Movement of saline water into freshwater aquifers • Driven by lowering of aquifer freshwater levels
Groundwater Flow Patterns (Ranjan, 2007)
SALTWATER INTRUSION?
Three primary mechanisms:
• Subsurface sea water
movement (large scale
intrusion)
• Seepage from tidal canals &
streams
• Lowering water table (well
extraction)
well
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2nd Week of 4/2016 3rd Week of 4/2016 1st Week of 5/2016 (forecast)
Station Nha Be Cat Lai Ferry Thu Thiem Ong Thin Canal C An Ha canal bridge bridge sewerage
Salinity > 4 - 14 0/00 for all stations (2016)
SALINE INTRUSION IN HCMC
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SALINE INTRUSION: RED RIVER DELTA
Red River Delta (Wikipedia)
• Offshore salinity: 33‰ in dry season &
32‰ in “flood” season.
• Coastal salinity: 25 - 29 ‰.
• Sea level rise 1 m → 1.668 km2 area
waterlogged, affects 1.874.011 people.
• Lack of water in dry season.
(Vu Minh Cat, 2006)
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Bac Lieu & Ca Mau provinces: saline water 20 g/L.
Fruit’s price loss in Ben Tre: 3,000 - 7,000 millions VND.
Drough have worsened the sanility problems in Bac Lieu province (Khanh Hoa, 2016)
SALINE INTRUSION IN MEKONG DELTA
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Damaged in Cu Lao Dung, Soc Trang province,
31,000 ha of rice fields, upland gardens, fruit orchards & shrimp farms.
24,000 ha of rice & sugarcane cultivation
23,000 farming families.
Sugarcane field is destroyed by saltwater intrusion in Cu Lao Dung
district, Soc Trang province in 2015 (Nhan Dan New, 2015)
SALINE INTRUSION
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• A temporary solution
• Unclear quality
• Release plastic wastes
SOLUTION: BOTTLED WATER
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Salt intrusion Lack of freshwater for drinking (Survey from 1001 Fontain Co.)
Best choice
for local
people
• 100% of households already drink 20 L BW
• 70% use 20L BW as their only drinking water source
• Average price = VND 11,000 for 20L ($2.4 cts / liter)
• 14 different brands observed in 1 street!
SOLUTION: BOTTLED WATER
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0
10
20
30
40
50
60
70
80
Price (
thousand V
NĐ
)
Brand
Famous Brand
Local Brand
SOLUTION: BOTTLED WATER
20 L
Bottled Water
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Preventing salt intrusion
by water gate in Hau Giang
Combine rice farming
in rotation with shrimp culture
SOLUTION: DAM & FARMING MODEL
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+ Prevent sea water intrusion, regulate temperature & salinity of pond
water, treat wastewater, clean the air, minimize impact of
environmental pollution.
+ Can combine with aquaculture to bring high economic efficiency
SOLUTION: Mangrove Forest
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Built on the mouth of river reduce coastal salt water intrusion
by constructing offshore sand islands creates a tidal area
with brackish water.
Balance island in Haringvliet, Netherlands (www.dutchwatersector.com, 17/2/2015)
SOLUTION: BALANCE ISLAND
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Water Reservoir: increase water storage, ensure continuously water
supply
Lake Biwa, Japan (www.water.go.jp)
Lake Biesbosch, Netherlands (www.aerostockphoto.com)
SOLUTION: WATER RESERVOIR
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CURRENT DESALINATION TECHNOLOGY
RO is currently the Best Available Technology (B.A.T) for salt removal from water
Reverse Osmosis (RO)
Distillation
Ion exchange
Electro Dialysis
(ED)
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CURRENT DESALINATION TECHNOLOGY
Reverse Osmosis Technology
Advantages:
•Apply for sea water treatment;
•Good treatment performance;
•Large scale system;
•Currently wide application;
Drawbacks:
• High investment/operation cost (OPEX 0.25 $US/m3
, CAPEX 0.45 $US/m3 - Garcia et al., 2013)
• High pressure pump (~100 bar)
• Pretreatment (anti-scaling) required;
• Not effective for very high TDS water;
• Less removal of organics.
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DIRECT CONTACT MEMBRANE DISTILATION
SYSTEM
Only vapor (hydrophobic) pass through hydrophobic membrane
Pore size: 0.45 µm
Flux: 4.1 L/m2.h
Start
Product
28 oC
vapor
Liquid
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TREATMENT PERFORMANCE OF DCMD
No. Parameters
RO Membrane (Lee et al., 2016)
Membrane Distillation (This study)
Effluent Removal Effluent Removal
1 TDS < 129.7 mg/L ~ 99 % < 20 mg/L 99.69 %
2 Chloride - - < 1.4 mg/L 99.93 %
3 Sulfate - - <1.9 mg/L 99.4 %
Concentrated water
• Make sea salt; • Discharge into sea; • Use as draw solution in FO tech.
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• Sea level rise will increase 62-82 cm in 2100 Vietnam
will lose 39% total area of Mekong Delta, 16.8% total area
of Red River Delta;
• Salt conc. increases by 1.2-10 0/00 & moves deeper inland
in the future;
• Water will be scarcity in terms of quality & quantity;
• Advanced water treatment & desalination technologies
must be applied.
• Sustainable water management policy!
CONCLUSIONS
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Thank You!
• HCMUT; Temasek Polytechnic (Singapore) • EPFL (Switzerland); ENSIL (France)
BIOSEP Research Group:
Dr. Bui Xuan Thanh
Ho Chi Minh City University of Technology [C] +84-965-37-6073
[I] www.buixuanthanh.com
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