SWITCH WORKSHOP ONINTERGRATED URBAN WATER MANAGEMENTINTERGRATED URBAN WATER MANAGEMENT

WASTEWATER REUSE AS A CLIMATE CHANGE

ADAPTATION MEASUREADAPTATION MEASURE

CASE OF CAN THO CITY

TRINH THI LONGTRINH THI LONGSOUTHERN INSTITUTE OF WATER RESOURCES RESEARCH

CLIMATE CHANGE ranks among the

VIETNAM

a s a o g t etop five developing countries most

impact

VIETNAM cou es osimpacted by climate change i t g

h b id tifi d

impact

has been identified as being particularly

tibl t thsusceptible to the impacts of extreme li t t dclimate events and

climate variability

ClimateClimate change

DROUGHTS

FLOODS

These two extreme weather di i illconditions will occur

much more oftenmuch more often

Temperature increases from 33 – 35 °C to 35 – 37 °C

Rainfall decreases about 10 – 20%The dry seasons are predicted to lengthen and intensify

Change in monthly rainfall in the Mekong Delta (mm)Total annual rainfall in An Giang, Can Tho and Soc Trang will decrease about

20%, and rainy season will start 2 weeks later.With the use of Global Circulation Models (GCMs) combined with the downscaling regional climate modelWith the use of Global Circulation Models (GCMs) combined with the downscaling regional climate model PRECIS and series of data from 1980 – 2000, University Chulalongkorn - Thailand and Climate Change Research Institute – Can Tho University (Vietnam) have done the forecasting for the year 2030-2040 that many areas in the Mekong Delta will get serious impacts due to climate change

Average humidity (1999 - 2008)

858687

y (%

)

Average Annual Rainfall (1999 - 2008)

1800

1900

2000

(mm

)

8081828384

Hum

idity

1400

1500

1600

1700

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Rai

nfal

l (

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008 year

average humidity Power (average humidity)

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

YearAverage Rainfall Pow er (Average Rainfall)

humidity has a trend of decreasing 5%Rainfall decreasing 200mm/year

Radiation (1998 - 2008)

2600

2800

ear)

Average Temperature (1999 - 2008)

27,1

27,2

27,3

ure

)

humidity has a trend of decreasing 5%

1600

1800

2000

2200

2400

Rad

iatio

n (h

our/

ye

26,6

26,7

26,8

26,9

27

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Tem

pera

t(T

oC)

1400

1600

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

R

Radiation Power (Radiation)

YearAverage Temperature (1999-2008)

Pow er (Average Temperature (1999-2008))

air-temperature increasing 0 2 0C sun radiation increasing 200 hours/year air-temperature increasing 0.2 C g /y

From 2000 to 2007 in Hau river at Tan Chau, water level is decreased 0.8m, meanwhile the max water level in Can Tho is increased 0.3m with decreasing precipitation in the area facilitate salinity to intrude deeply into the landp p

In the dry season of the year 2006, 2007 and 2008 water discharge of Hau river was only 800 m3/s instate of 1250 m3/s in about 30 years ago

facilitate salinity to intrude deeply into the land

Rain water with total average calculationfor 10 year (1999 – 2008) is about 2.3billion m3/year. If making use of thisbillion m3/year. If making use of thissource, it’s nearly enough for domestic usein 3 months in the dry season.However, it’s not possible to havest 100%

f th i t

WATER SURFACE WATER

of the rainwater.

?WATERRESOURCES

SURFACE WATER ?GROUNDGROUNDWATER

Over-extraction, saltwater intrusion,

D i f d t l l i T N I d t i land pollutionDesigned capacity: 163,558 m3/dayActual extraction: 101,061 m3/day

Depression of groundwater level in Tra Noc Industrial zone

Well 5 m3/day: 32,000; 50 m3/day: 400; 500 – 1000 m3/day: 30; 200 GWP in 2010

158 rivers and canals158 rivers and canals

779 km of main (primary) canals

2000 k f d l 60 km2000 km of secondary canals

120 – 150 tertiary canals in each rural district

60 km

Discharge water in Bassac river: about 200 billion m3/year. Rainy season: about 81% of the annual discharge Dry season: about 19% In exhausted months from March to May: only about 4%.

Water qualityq yOrganic pollution in river/canal system of Can Tho City

25,0

30,0

COD in canal system (9/2010)

60 00

70,00

80,00

5,0

10,0

15,0

20,0

CO

D (m

g/l)

10 00

20,00

30,00

40,00

50,00

60,00

CO

D (m

g/l)

-1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

YearVN standard Cantho river Cai Khe canalTranoc Canal O Mon canal Thot Not canalCai San canal Hau river

0,00

10,00

1 2 3 4 5 6 7Sampling station

Thoi Lai O MOn Ninh Kieu-TT Ninh Kieu-CK Vinh Thanh

Thot Not Cai Rang Binh Thuy VN Standard

Total N in canal system (9/2010)

25,000

30,000

35,000

l)

Total P in canal system (9/2010)

2 5003,0003,5004,000

g/l)

0,000

5,000

10,000

15,000

20,000

T-N

(mg/

l

0,0000,5001,0001,5002,0002,500

1 2 3 4 5 6 7 8T-

N (m

g,

1 2 3 4 5 6 7 8

Sampling stationThoi Lai O Mon Ninh Kieu-TT

Ninh Kieu-CK Vinh Thanh Thot Not

Cai Rang Binh Thuy MRC Value

1 2 3 4 5 6 7 8

Samling stationThoi Lai O MOn Ninh Kieu-TT

Ninh Kieu-CK Vinh Thanh Thot Not

Cai Rang Binh Thuy MRC value

Pollution sources???

WATER POLLUTION DUE TO COD FROM DOMESTIC WASTEWATERWASTEWATER

• According to WHO people in the city have discharged household waste at an average of 0.87kg/day/person

• If this amount of pollution is diluted with rainwater in the year it willwith rainwater in the year, it will cause rainwater polluted.

• in 1999 every person in Can Tho city polluted rainwater with y p12mgCOD/l;

• in 2008 it is up to 16 mg COD/l • It exceeds the Vietnamese standardIt exceeds the Vietnamese standard

level A1 with water source for water supply for domestic use (QCVN 08: 2008/BTNMT). M th id f dil ti• Moreover, the idea of diluting wastewater to achieve standards is nowadays not acceptable anymore

WATER POLLUTION DUE TO COD FROM WASTEWATER OF FISH PONDWASTEWATER OF FISH POND

• 12,216 fishponds: average of a 2m depth (varies from 1 5 4m)(varies from 1.5 – 4m)

• upon renewing the pond water discharge amounts of up to 70 million m3/day = 27 billion m3/yearTh t t f COD i fi h d b t• The content of COD in fishponds can be up to 80mg/l.

• If this wastewater is diffused with the flow of the Hau River in the best conditions, the river water will carry 10mg/l of COD (exceeds QCVNwater will carry 10mg/l of COD (exceeds QCVN 08: 2008/BTNMT)

• For pond “Tra” fish breeding in Thot Not District: 25 9% of the farmers discharged pond• 25.9% of the farmers discharged pond effluents into the Hau River,

• 34.3% into the canals, • 5.6% into settling ponds, and • 34.3% into paddy fields. • Most of respondents (60.2%) reported that they

dumped wastewater into public water sources, while 39.8% dumped it onto private land.% p p

WATER POLLUTION DUE TO COD FROM AQUATIC PRODUCT PROCESSING INDUSTRY

• Aquatic product processing wastewater daily: 15 000m3

PRODUCT PROCESSING INDUSTRY

daily: 15.000m3• Average COD: 1,500mg/l. • Rivers and canals in Can Tho City

i 22 500 t f COD dreceive 22,500 tons of COD every day. • At this moment, most of the industrial

estates in Can Tho City do not possess a concentrated wastewater treatmenta concentrated wastewater treatment system.

• Presumably, two-thirds of the COD concentration is disposed of leavingconcentration is disposed of, leaving just one-third of the unprocessed COD to be diffused with Hau River water.

• However the concentration of CODHowever, the concentration of COD after dilution is up to 13.6 mg/l,

• Exceeds the Standard QCVN 08: 2008/BTNMT2008/BTNMT

So, only one of those sources can makewater quality in river/canal system of CanTho city exceeds the permissible limitationof the current National Standard QCVN 08:2008/BTNMT.

Meanwhile, Can Tho has all those 3 sources.

This is the reason that concentration ofCOD in surface water is increasing everyyear even with high flow of Hau river andpollution water if wash out to the seaeveryday.

Sewage system in Can Tho city

WWTPTotal amount of 18 7million EurosTotal amount of 18,7million Euros Vietnam approximately 52% KfW and 48%

Capacity 22,550m3/d, Maximum hydraulic flow of 0,726 m3/sec

Mechanical treatment and biological reduction of BOD and CODBOD and CODTCVN – B LEVEL

WWTPTCVN 5945 – 2005

BOD: 50 mg/lCOC: 80 mg/l

INCREASINGPOPULATION

CLIMATE POPULATION

URBANISATION

CHANGE

INDUSTRIALISATION DROUGHT

SALINITY INTRUSION

INCREASING WATER

ACID WATER SPREADING

DEMAND

POOR W.W MANAGEMENT WATERMANAGEMENT

POOR RUNOFF WM

WATER SCARCITY??

REUSEREUSE WASTEWATERWASTEWATERAS A CLIMATEAS A CLIMATE

CHANGECHANGE ADAPTATIONADAPTATION

MEASUREMEASURE

Thot NotVinh Thanh

Cropping calendar, monthly rainfalland water demands in Can Tho

Co Do

effluenteffluenteffluent

Advantages of reuse of wastewater in agriculture

C t (b li d d t• Conserves water (by recycling and groundwater recharge);I l t th d f it di l f• Is a low-cost method for sanitary disposal of municipal wastewater;R d ll ti f i d th f• Reduces pollution of rivers and other surface water;C t i t th b d i th d• Conserves nutrients, thereby reducing the need for artificial fertilizer;I i ld d• Increases crop yields; and

• Provides a reliable water supply to farmers• Use for pushing seawater purposes

Thank you very muchy yFor your attention