International Conference on Forward-looking Water Management November 8-9, 2018 Organized by. Water Resources Agency, MOEA, Taiwan

Transcription

1 1 International Conference on Forward-looking Water Management November 8-9, 2018 Organized by Water Resources Agency, MOEA, Taiwan Dr. BUI Xuan Thanh Associate Professor Faculty of Environment & Natural Resources Ho Chi Minh City University of Technology ( ) Taipei - Taiwan

2 2 CONTENT 1 General Information 2 Water Pollution in Viet Nam 3 Solutions 4 Conclusions

3 GENERAL INFORMATION 3 Vietnam Delta (Wikipedia) Two biggest deltas in Vietnam: 68.4% of country rice cultivated areas 71.3% of rice quantity Red River Delta: Population: people Total area: km 2 Density: 949 people/km 2 Mekong Delta: Population: people Total area: km 2 Density: 427 people/km 2

4 VIETNAM WATER MARKET 4 Investment demand (Statistics Ministry of Construction, 2018) In the next 5 years, the demand for water sector investment 10 billion USD Water Supply 3.3 billion USD Water Drainage 6.9 billion USD

5 VIETNAM WATER MARKET 5 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 m 3 /day Price: Vary with locations & water resources (1$ =23,000 VND Location Company Price (VND/m 3 ) 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

6 VIETNAM WATER MARKET 6 Profit: Saigon Water Corp. (SAWACO): subsidy (Doanh nhan Sai Gon, 10/7/2018) PHUWACO water supply JSC: Net profit ~ 6.53% in (after 5 years) Ben Thanh WASUCO JSC: Net profit ~ 3.3% in 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.

7 7 WATER SUPPLY - HCMC Water Production and Distribution of SAWACO Water supply planning until 2025 (Prime Minister Decision 729/QĐ-TTg) Others (Private company) Tan Phu WTP Kenh Dong WTP Tan Hiep WTP BOO Thu Duc WTP BOT Binh An WTP Thu Duc WTP Ground water Surface water Sai Gon River Surface water Dong Nai River 75,000 m 3 /day (5%) 1,445,000 m 3 /day (95%) (SAWACO, 2014)

8 8 Surface Water Issues

9 ORGANIC POLLUTION In SAIGON RIVER 9 Saigon river water quality is being deteriorated with time, increase in organic & ammonia pollution (Dan et al., 2013) Variation of COD & DOC along Saigon river: From Dau Tieng lake to Downstream (km) COD, DOC > standard limit for water supply purpose

10 NUTRIENT POLLUTION In SAIGON RIVER (Dan et al., 2013) Variation of TKN & Ammonia along Saigon river: From Dau Tieng lake to Downstream (km) Ammonia > Standard limit for water supply purpose (QCVN 08-MT:2015/BTNMT: NH 4 -N < 0.3 mg/l) 10

11 SAIGON WATER QUALITY: Hoa Phu STATION (SAWACO, 2016) 11 Parameter Unit ph ± ± ± ± ± 0.06 Color Pt-Co 288 ± ± ± ± ± 162 Turbidity NTU 41 ± ± ± ± ± 19 Alkalinity mg/l 17 ± 4 17 ± 2 16 ± 3 25 ± 4 25 ± 3 SS mg/l 31 ± ± 9 21 ± ± ± 12 Ammonia mg/l 0.47 ± ± ± ± ± 0.09 Nitrite mg/l 0.01 ± ± ± ± ± 0.02 Nitrate mg/l 0.50 ± ± ± ± ± 0.15 Fe mg/l 1.05 ± ± ± ± ± 0.18 Mn mg/l 0.13 ± ± ± ± ± 0.06 BOD 5 mg/l 4.6 ± ± ± ± ± 0.7 COD mg/l 12.0 ± ± ± ± ± 1.5

12 12 SURFACE WATER TREATMENT TECHNOLOGY Chlorine Chlorine Alum/PACl River Pump Station Receiving tank Mixing tank Sedimentation tank Distribution network Chlorine Reservoir Sand filtration Conventional treatment technology & use high chlorine dosage!!!

13 SECONDARY POLLUTION: THMs 13 Chlorine is widely used for disinfection & pre-chlorination in WTP DBPs. DBPs in drinking water serious problem to human health

14 Chlorine (g/m 3 ) CHLORINE DOSAGE Month 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) Dosing Dose (g/m 3 ) Chlorine demand (kg/day) min max Average At pump station At receiving tank At clean water storage tank Before pumping to pipe system Total

15 DOC, POC (mg/l) 15 DOC/TOC (%) THMFP ( g/l) ORGANIC & DBPs MONITORING (Dan et al., 2016) May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr POC DOC DOC/TOC THM standard THMFP TOC Month 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 ( μg/l)

16 16 THM Standard Limits in Different Countries concentration (ug/l) Total THM International Standards Vietnam Standards: (TTHM: 460 μg/l) QCVN 01/2009 Ministry of Health - CHCl 3 : 200 μg/l - CHCl 2 Br: 60 μg/l - CHClBr 2 : 100 μg/l - CHBr 3 : 100 μg/l 0

17 17 SURFACE WATER TREATMENT PLANT Compact Surface WTP in Long An province (built by SAWACO) Sedimentation tank in Thu Duc WTP

18 18 TECHNOLOGY EVALUATION 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!

19 19 Groundwater Issues

20 20 Arsenic contamination: + As = 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

21 21 (Khanh et al., 2013)

22 High As conc. was found at the well with depth of m. [16 samples in Long An province exceed the WHO s standard, 10 ppb] (Thanh et al., 2011) 22

23 23 GROUNDWATER TREATMENT TECHNOLOGY HCMC: Ground water Pump Station Tray aeration Chlorine Lime Mixing tank Chlorine Sedimentation tank Distribution network Reservoir Sand filtration Air contact + sand filtration Aeration tray + sand filtration

24 24 TECHNOLOGY EVALUATION 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. Can not remove Salt from water Need of novel tech.

25 Saltwater Intrusion 25

26 SALTWATER INTRUSION? 26 Movement of saline water into freshwater aquifers Driven by lowering of aquifer freshwater levels well Three primary mechanisms: Subsurface sea water movement (large scale intrusion) Seepage from tidal canals & streams Lowering water table (well extraction) Groundwater Flow Patterns (Ranjan, 2007)

27 27 SALINE INTRUSION IN HCMC Salinity > / 00 for all stations (2016) Nha Be Cat Lai Ferry Thu Thiem Ong Thin Canal C An Ha canal bridge bridge sewerage 2 nd Week of 4/ rd Week of 4/ st Week of 5/2016 (forecast) Station

28 28 SALINE INTRUSION: RED RIVER DELTA Red River Delta (Wikipedia) Offshore salinity: 33 in dry season & 32 in flood season. Coastal salinity: Sea level rise 1 m km 2 area waterlogged, affects people. Lack of water in dry season. (Vu Minh Cat, 2006)

29 29 SALINE INTRUSION IN MEKONG DELTA 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)

30 SALINE INTRUSION 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) 30

31 SOLUTION: BOTTLED WATER 31 A temporary solution Unclear quality Release plastic wastes

32 SOLUTION: BOTTLED WATER 32 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!

33 Price (thousand VNĐ) SOLUTION: BOTTLED WATER L Bottled Water Local Brand Famous Brand Brand 33

34 34 SOLUTION: DAM & FARMING MODEL Preventing salt intrusion by water gate in Hau Giang Combine rice farming in rotation with shrimp culture

35 SOLUTION: Mangrove Forest + 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 35

36 SOLUTION: BALANCE ISLAND Balance island in Haringvliet, Netherlands ( 17/2/2015) Built on the mouth of river reduce coastal salt water intrusion by constructing offshore sand islands creates a tidal area with brackish water. 36

37 37 SOLUTION: WATER RESERVOIR Water Reservoir: increase water storage, ensure continuously water supply Lake Biwa, Japan ( Lake Biesbosch, Netherlands (

38 CURRENT DESALINATION TECHNOLOGY Reverse Osmosis (RO) Electro Dialysis (ED) Distillation Ion exchange RO is currently the Best Available Technology (B.A.T) for salt removal from water 38

39 CURRENT DESALINATION TECHNOLOGY Reverse Osmosis Technology Advantages: Apply for sea water treatment; Good treatment performance; Large scale system; Currently wide application; 39 Drawbacks: High investment/operation cost (OPEX 0.25 $US/m 3, CAPEX 0.45 $US/m 3 - Garcia et al., 2013) High pressure pump (~100 bar) Pretreatment (anti-scaling) required; Not effective for very high TDS water; Less removal of organics.

40 DIRECT CONTACT MEMBRANE DISTILATION SYSTEM Start Liquid vapor Product Pore size: 0.45 µm Flux: 4.1 L/m 2.h 28 o C Only vapor (hydrophobic) pass through hydrophobic membrane 40

41 41 TREATMENT PERFORMANCE OF DCMD No. Parameters RO Membrane (Lee et al., 2016) Membrane Distillation (This study) Effluent Removal Effluent Removal 1 TDS < mg/l ~ 99 % < 20 mg/l % 2 Chloride - - < 1.4 mg/l % 3 Sulfate - - <1.9 mg/l 99.4 % Concentrated water Make sea salt; Discharge into sea; Use as draw solution in FO tech.

42 CONCLUSIONS 42 Sea level rise will increase cm in 2100 Vietnam will lose 39% total area of Mekong Delta, 16.8% total area of Red River Delta; Salt conc. increases by / 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!

43 Thank You! BIOSEP Research Group: Dr. Bui Xuan Thanh Ho Chi Minh City University of Technology [C] [E] [I] 43 HCMUT; Temasek Polytechnic (Singapore) EPFL (Switzerland); ENSIL (France)

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