WaterQuality Report

7/31/2019 WaterQuality Report

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V.3 Feasibility Study

V.3.1 Water Quality of WTC and Intercepted Rivers

Deforestation, urbanization and industrial development in the basin of the Citarum River justupstream of West Tarum Canal (WTC) and the basins of rivers (the Cibeet, Cikarang, and BekasiRiver) intercepted by the WTC have caused an increase of erosion and discharge of untreateddomestic and industrial wastewater, and have resulted in deterioration of the water quality in theWTC.

The water uses of WTC are irrigation, raw water supply to water treatment plants and industrial uses.Jakarta water treatment plants (WTP) take raw water on the downstream of WTC which are heavily

polluted. The present total raw water demand for Jakarta City is 16.1m3/sec.

WTC should belong to CLASS 1 as it supplies raw water for drinking water treatment, but sometimeslies even out of CLASS 4. Water quality management and rehabilitation programs need to beimplemented accordingly.

All the available water quality data of WTC and intercepted rivers (Cibeet, Cikarang, and Bekasi),will be collected and analyzed and the necessity of separation of the Cibeet and Cikarang River fromWTC will be evaluated for water quality improvement.

Also savings of various chemicals for the treatment processes of the WTP will be evaluated andcompared with the costs for construction of separation facilities of river flows into WTC, taking intoaccount the present and improved water quality in the WTC.

Key Water Parameters for Raw Water of Water Treatment Plant

Parameters Units Class1*

Temperature C Dev.3TDS mg/L 1000

SS mg/L 50

Turbidity NTU -

pH mg/L 6-9

BOD mg/L 2COD mg/L 10

DO mg/L 6

NH3-N mg/L 0.5

NO3-N mg/L 10

Fe mg/L 0.3

Mn mg/L 0.1

*River Water Classification (Gov. Regulation No. 82/2001 Concerning Water QualityManagement)

**

A. Data Collection


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Water quality data covering 1993-2010 provided by PJT II for 13 stations (Figure 5.1) along the WestTarum Canal includes the following parameters:

Physical parameter: temperature, TDS, turbidity

Chemical parameter: pH, DO, Fe, Mn, Zn, NH3-N, NO2-N, NO3-N, SO4, Cl, H2S, BOD5, andCOD.

Water Quality Monitoring Locations in the Citarum River Basin

The following is an available data from Pejompongan Water Treatment Plant in 2005. A recent datawill be collected and updated to make a better prediction of raw water quality improvement andchemical costs reduction in case of separating the Bekasi and/or Cikarang and/or Cibeet River flowsfrom WTC.

1. Six hourly measurement data for turbidity, pH, temperature, and color.2. Daily measurement data for conductivity, ammonia, iron and Total Coliform3. Weekly measurements data for hardness, manganese, nitrite, nitrate, organic matter, TDS,

BOD, COD and DO.

4. Monthly measurement data usually for a group of metal Mercury, Arsenic, Barium,Cadmium, Chromium, Selenium, Zinc, Copper, Lead, Calcium including Detergent, Sulfate,Sulfide, Chloride and Fluoride.

B. Important Water Quality Parameters for Water Quality Management and Water Treatment

Biochemical Oxygen Demand (BOD)

Biochemical Oxygen Demand (BOD) is not a drinking water parameter. It is most commonly used todetermine the amount of dissolved oxygen needed by aerobic microorganisms to break down organicmaterial in a body of water during the period of 5 days at 20C. It is widely used as an indication ofthe organic quality of water. BOD itself will not say any health effect but show amount of oxygendepletion which can happen in waters, therefore, becomes one of the most important parameters forriver water quality management. River water quality is divided into 4 classes depending on presentwater quality and intended uses of water bodies. BOD is one of the most affecting parameters forclassification.


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Suspended Solids

Suspended solids in water consist of two fractions an inorganic oneconstituted of silts, clays, etc. and an organic one consisted of plankton,

bacteria and others. All these constituents enter into flowing water by surfacerun off during rain and man-made wastewater from population and industry.For natural surface runoff, the inorganic portion in suspended solids is usuallyhigher than the organic one, however, wastewater has more organic portionthan surface runoff.

Turbidity is a measure of the light-transmitting properties of water. Therefore,this parameter is used to indicate the quality of water with respect tosuspended matters and colloidal particles to which the turbidity correlates.In this respect, it is important note that there is an approximate relationshipbetween turbidity and total suspended solids as:

Total Suspended Solids TSS (mg/l) ~ conversion factor x Turbidity (NTU)

This correlation between the two parameters is fundamental in assessingimpurity in surface water as it will be much easy and less expensive to get anaccurate estimate of total suspended solids in water from continuouslymonitored turbidity.

The conversion factor of total suspended solids versus turbidity is often takenequal to 1. Suspended solids can then be assimilated to Turbidity: TSS (mg/l)~ Turbidity (NTU).

Turbidity

The measurement of turbidity is a simple useful indicator of the condition of water. For filtrationfacilities, turbidity is also a surrogate for suspended sediment and associated adsorbed chemical

contaminants, so reducing turbidity and associated treatment costs often goes beyond simplyimproving the aesthetic quality. Some particles may contain pathogenic organisms and interfere withdisinfection by sheltering microorganisms.Raw water turbidities can vary over a very wide range, from virtually zero to several thousand NTU.Effective treatment should be able to produce final waters with turbidity levels of less than 1 NTU,which is recommended for efficient disinfection with chlorine. The Indonesian drinking waterstandards set 5NTU. WHO Guidelines also set 5 NTU as the maximum level acceptable to consumers,

but also set less than or equal to 1 NTU as a treatment standard for successful disinfection. Ingestionof Giardia cysts and Cryptosporidium oocysts excreted by animals or humans were found to causeacute diarrheal disease, and are more resistant to chlorine than bacteria and viruses. More recentlyhowever, the need to ensure the removal of them has led to turbidity targets of less than 0.1 NTU

being applied to filtered waters.Turbidity is also the most important quality parameter that affects the coagulant dose for watertreatment.

Ammonia

Ammonia is one of the forms of nitrogen found in water. It exists in water as ammonium hydroxide(NH4OH) or as the ammonium ion (NH4

+), depending on the pH value, and usually expressed in termsof mg/L free ammonia. Ammonia originates from various sources, but the most important isdecomposing plant and animal matter. Increased levels of free ammonia in surface water may be anindicator of recent pollution by either sewage or industrial effluent. The level of free ammonia in rawwater is of importance in determining the chlorine for disinfection. Chlorine first combines with

ammonia to form chloramines. Free chlorine is a more effective disinfectant than chloramines. TheWHO considers that there is no health risk associated with the levels of ammonia found in drinking


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water and suggests a maximum level of 1.5 mg/L ammonia to avoid taste and odor problems.Indonesian drinking water standard is also 1.5mg/L.

Other parameters will be examined to evaluate whether they will be necessary or not. A graphicalmethod is used to interpret the relation of each quality variable. A further statistical method is used toexplain the variation of water quality data.

C. Water Quality Levels at WTC and Crossing Rivers

100908070605040302010099989796959493

30

25

20

15

10

5

0

Y e a r

BOD,m

g/L

1 C u r u g

1 1 C ib e e t

1 2 C i k a r a n

1 3 B e k a s i9 B T b . 5 1

BOD levels at the West Tarum Canal and crossing rivers during the period 1993-2010

100908070605040302010099989796959493

16000

14000

12000

10000

8000

6000

4000

2000

0

Year

Turbidity

,NTU

1 Curug

11 Cibeet

12 Cikarng

13 Be ka s i

9 BTb .51

Turbidity levels at the West Tarum Canal and crossing rivers during the period 1993-2010


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201020092008200720062005

20

15

10

5

0

Ye a r

BOD,mg/L

1 Curug

11 Cibeet

12 Cikarang

13 Bekas i9 BTb.51

BOD levels at the West Tarum Canal and crossing rivers during the period 2005-2010

20092008200720062005

6000

5000

4000

3000

2000

1000

0

T

urbidity,

NTU

1 Curug

11 Cibeet

12 Cikarng

13 Be ka s i

9 BTb .51

Turbidity levels at the West Tarum Canal and crossing rivers during the period 2005-2010


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100908070605040302010099989796959493

30

25

20

15

10

5

0

Ye ar

BOD,mg/L

1 Curug

2 BTb.10

3 BTb.23

4 BTb.35

5 BTb.45

6 BTb.49

8 P ulogadung Intake

9 BTb.51

BOD levels along the West Tarum Canal during the period 1993-2010

100908070605040302010099989796959493

6000

5000

4000

3000

2000

1000

0

Y e a r

T

urbidity,

NTU

1 C u r u g

2 BT b .10

3 BT b .23

4 BT b .35

5 BT b . 45

6 BT b .49

8 P u l o g a d u n g I n t

9 BT b .51

Turbidity levels along the West Tarum Canal during the period 1993-2010


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10Pejom

ponganIn

take

14BTb

.53

9BTb

.51

6BTb

.49

8PulogadungIn

take

7BuaranIn

take

13Beka

si

5BTb

.45

4BTb

.35

12Cika

rng

3BTb

.23

11Cib

eet

2BTb

.10

1Cu

rug

14

12

10

8

6

4

2

BOD,mg/L

2002

2003

2004

2005

2006

2007

2008

2009

2010

1993

1994

1995

1996

1997

1998

1999

2000

2001

Yearly Average BOD (1993 - 2010)

Yearly average BOD at the West Tarum Canal and crossing rivers during the period1993-2010

10Pejom

pongan

Intake

14BTb

.53

9BTb.51

6BTb.49

8Pulogadung

Intake

7Buaran

Intake

13Bekasi

5BTb.

45

4BTb.35

12Cika

rng

3BTb.23

11Cibeet

2BTb.10

1Curug

9000

8000

7000

6000

5000

4000

3000

2000

1000

0

Turbidity,

NTU

2002

2003

2004

2005

2006

2007

2008

2009

2010

1993

1994

1995

1996

1997

1998

1999

2000

2001

Yearly Average Turbidity (1993 - 2010)


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Yearly average turbidity at the West Tarum Canal and crossing rivers during the period1993-2010

14BTb

.53

9BTb

.51

6BTb.49

8Pulogadung

Intake

7Buaran

Intake

13Bekasi

5BTb.

45

4BTb.35

12Cika

rng

3BTb

.23

11Cibe

et

2BTb.10

1Curug

11

10

9

8

7

6

5

4

3

BOD,mg/L

Oct

NovDec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Monthly Average BOD (1993 - 2010)

Monthly average BOD at the West Tarum Canal and crossing rivers during the period1993-2010


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14BTb.5

3

9BTb.5

1

6BTb.4

9

8Pulogadung

Intake

7Buaran

Intake

13Bekas

i

5BTb.4

5

4BTb.3

5

12Cikarn

g

3BTb.2

3

11Cibee

t

2BTb.1

0

1Curu

g

2000

1500

1000

500

0

Turbidity,

NTU

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Monthly Average Turbidity (1993 - 2010)

Yearly average turbidity at the West Tarum Canal and crossing rivers during the period1993-2010

Figure 5.2 shows BOD5 trend in the WTC and the crossing rivers during the period 1993-2010. Alsothe turbidity trend in the WTC and the crossing rivers during the same period is shown in Figure 5.3.If the figures show that three rivers are more polluted and in deteriorating trends are visible, Cibeet

partition wall and siphon construction, and/or Cikarang siphon construction can be justified. Thewater qualities of upstream and downstream of WTC, and three rivers were deteriorating until 1998,

but did not further based on BOD5.Tubidities of the three rivers and the upper WTC remained lowuntil 1997, but were in a rapidly increasing trend until 2004. Since 2005 past distinct differences inwater qualities between WTC and three rivers have been reduced, however still three rivers arefrequently poor in water quality by considerable margin as shown in Figure 5.4 and Figure 5.5 drawnon the increased scale of y-axis to distinguish three rivers and WTC by BOD and turbidity. Althoughrivers with high BOD and turbidity intersect the WTC, the BOD and turbidity levels do not increasedownstream of WTC in a considerable degree (Figure 5.6 and Figure 5.7). This may be the result of

BOD causing material being self purified and suspended solids being settled flowing along WTC. Onsome monitoring dates, BOD and turbidity increase gradually after the confluence of the Bekasi Riverwith WTC. At present, a lot of existing polluted drainage water comes into the WTC passing through

populated areas after the confluences of three rivers with WTC, and deteriorates the quality of thecanal water. In addition, communities close to the canal banks of WTC commonly disposeliquid and solid wastes directly into waterways.Water quality data provided by PJT II have 16 parameters measured monthly on the Citarum RiverBasin. Sometimes data are missing for months and sampling period are not consistent. It is difficult toassess the state of water quality in the three rivers and WTC with only monthly measured data.The quality of storm water depends on the pollution washed off from the catchment surfaces,fertilizers and pesticides in runoff from agriculture and silt (sediment) in runoff. The pollutants can be

trapped at the weirs and re-suspended from the sediment in the conditions of canal flow, and thelevels of water quality can vary. Water quality data may need to be correlated to precipitation andflow data. Diurnal variation in water quality due to discharge patterns of sewage and industrial


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wastewater may not be ignored. Sampling coinciding with cyclic pattern of discharging waste cancause increasing tendency of turbidity and BOD. These mean that concentrations and quantities of

pollutants during any sampling time and period may not represent the actual state of water quality,and show only concentrations at one moment of sampling. It may be one of reasons why the

tendencies of water quality in three rivers and the upper WTC are not consistent.Figure 8 and Figure 9 show yearly average BOD and turbidity from 1993 to 2010. Figure 10 andFigure 11 show monthly average BOD and turbidity from 1993 to 2010. Monthly average BOD andturbidity of three rivers have been much higher than those in WTC even though yearly BOD andturbidity differences between three rivers and WTC seem to be decrease since 2005.

Photo 1 shows the confluence of the Cibeet River with WTC. At the confluence of Cibeet River,turbid river water does not mix with WTC water flowing along the left bank of WTC. Thisshows the feasibility of construction of partition wall and siphon to separate turbid Cibeet waterwithout mixing with WTC water, and supply through the siphon to the Kedunggede irrigationcanal.

Confluence of the Cibeet River with WTC

Based on preceding consideration on BOD and turbidity differences between two rivers (Cibeet Riverand Cikarang River) and WTC, the Cibeet River needs to be separated to decrease turbidity mixingwhich induces high levels of turbidity in WTC. On the other hand the Cikang needs separation as itinduces high BOD in WTC.

D. Drainage inlets into the WTC

At present, a lot of existing polluted drainage water come into the WTC passing through urban areas

and deteriorates the quality of the canal water. The consultants will locate drainage inlets intothe WTC and investigate measures to isolate and divert the drainage flow into natural drains or

proposed parallel drains. Especially, measures are required in the section Bekasi-Jakarta and inother sections of the WTC passing through densely populated areas and which are vulnerable to

pollution.

V.3.2 Treatment Processes and Treatment Cost of WTPs along the WTC

WTC supplies raw water to the water treatment plants (WTP) of PAM-Jaya in Jakarta. The WTP thatreceives raw water from WTC is Pejompongan I & II (6.2 m 3/sec), Pulogadung (4.4 m3/sec) andBuaran I & II (5.5 m3/sec). The total raw water demand for Jakarta City is 16.1 m3/sec. In addition,


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sedimentation and filtration.Figure 5.14 shows the frequency of raw water turbidity distribution of 1819 at Buaran WTP from

2006 to 2010. In 1819 days with turbidity measurements, daily average had 132 days of turbidity

1000-3000 NTU and 40 days of turbidity over 3000 NTU, while daily maximum had 134 days of

turbidity 1000-3000 NTU and 183 days of turbidity over 3000 NTU. As maximum turbidity 317 dayshad turbidity over 1000 NTU in five years, that is, raw water turbidity exceed 1000 NTU on 63 days

in one year having difficulties in treating highly turbid water.

High turbidities were generally observed in September to May, that is, during the wet season, while

low turbidities were in July to October in the dry season (Figure 5.13).


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Daily average, maximum and minimum turbidity of raw water at Buaran WaterTreatment Plant


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20000100006000300010005001005010

160

140

120

100

80

60

40

20

0

Turbidity, NTU

Frequency

00000022

9

1817

2932

282323

333428

34

42

80

115117122122

148

141

118

78

110

129

101

57

26

100000

Daily average

30000200001000060003000100050 01005010

140

120

100

80

60

40

20

0

Turbidity , NTU

Frequency

113

17

29

37

161724

30

16

292526

36

2024

34

53

7574

10 6

80

11 2

98

123

13 5

10 9

86

10 710 9

90

64

11

1100000

Daily maximum

20000100006000300010005001005010

200

150

100

50

0

Turbidity, NTU

Frequency

000000000001134

1

1013

2228

4441

60

81

127

153

180

157

171

130

116

102

167

68

76

58

13001

Daily minimum

Figure 5.14 Raw water turbidity distribution at Buaran WTP during the period 2006-2010

Keeping NTU value constantly lower could reduce the production costs of WTP including electricity,chemical costs, etc. as well as could supply constant production of water to the 5 million people andother demanders.


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Intake gate of the Buaran WTP Water purification facilities of Buaran

WTPB. Chemicals Used in Water Treatment Plant

The main chemicals used for the treatment of raw water are mainly, aluminum sulfate (alum), lime,chlorine and powdered activated as shown in Table 5.3.Large amount of coagulants are used to aggregate turbidity causing colloidal particles for settling, and

the amount of coagulant used generally increases with increasing turbidity. A one percent increasein turbidity is shown to increase chemicals by one fourth of a percent in the range of turbidityfrom 6 to 89 NTU in Texas, USA (Dearmont et al. 1997). Ridwan and Nobelia (2009)estimated that one percent increase in turbidity of 25.5-277 NTU would cause one fifth percentincrease of Alum Sulfate used as coagulant. They analyzed statistically turbidity, pH, alkalinityand NOM (Natural Organic Matters) data obtained from Ciparay Water treatment Plant whichuse Upper Citarium River as a source. Turbidity showed the greatest influence on thedetermination of coagulant dose compared other parameters. Turbidity range is rather wide and

high in WTC, but in this way reduction in chemical costs from water quality improvement canbe estimated by examining the quantity of chemicals used at the time of different raw waterquality at the water treatment plant which takes raw water from the downstream of WTC.Labor and maintenance for more doses of chemicals and disposal of more sludge producedshould be considered. If raw water contains toxic inorganic and organic contaminantsexceeding the maximum contaminant level (MCL), costly advanced treatment processes areintroduced to remove contaminants.

Chemicals used for surface water treatment

Chemical Use

Alum (aluminum sulfate) CoagulationFerric sulfate Coagulation

Polymer Coagulation aid

Lime pH adjustment

Caustic soda pH adjustment

Soda ash pH adjustment

Chlorine Disinfection

Sodium chlorite Disinfection

Activated carbon Taste and odor control


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Chemicals used at the Buaran Water Treatment Plant

Chemical Component Use Price

Alum (Liquid) Aluminium sulphate Coagulation $200-400 perton

PAC Polyaluminium chloride Coagulation$300-320 perton

Sudfloc A Aluminiun chlorohydrat Coagulation$750-800 perton

LT20 Polyacrylamide Flocculation aid LT7994

Polydiallyldimethylammonium Chloride

Flocculation aid $4.99 per kg

Lime Calcium hydroxide pH adjustment$90-200 perton

Chlorine Liquid chlorine Disinfection$100-300 perton

Table 5.4 shows the chemicals which are used at th Buaran WTP. Three kinds of coagulants (Alum,PAC and Sudofloc A) and two kinds of polymers are used to cope with incoming extremely highturbidity with high frequency as shown in Figure 5.13 and Figure 5.14.Table 5.5 shows the relations between turbidity and concentrations of chemicals used.

Relation between daily average turbidity removed and chemicals used

Regression equations R 2, Adjusted R2

Turbidity removed = - 411 + 2.65 Alum + 0.67 PAC + 12.4 Sudofloc A+ 1919 Total polymer R-Sq = 61.7% R-Sq(adj) = 61.6%

Turbidity removed = - 457 + 13.3 Alum + 5.06 PAC + 123 Sudofloc A R-Sq = 29.4% R-Sq(adj) = 29.3%

Turbidity removed = 183 + 4.71 Alum R-Sq = 1.6% R-Sq(adj) = 1.5%

Turbidity removed = 374 - 10.2 PAC R-Sq = 0.5% R-Sq(adj) = 0.4%

Turbidity removed = 118 + 93.5 Sudofloc A R-Sq = 19.1% R-Sq(adj) = 19.1%

Turbidity removed = - 384 + 1.91 Total coagulant + 1995 Total polymer R-Sq = 61.6% R-Sq(adj) = 61.5%

Turbidity removed = 29.5 + 7.93 Total coagulant R-Sq = 3.9% R-Sq(adj) = 3.8%

Turbidity removed = - 312 + 2018 Total polymer R-Sq = 61.2% R-Sq(adj) = 61.2%

In general one kind of coagulant is used in moderately turbid raw water. Turbidity of raw water variesin the wide range of 3-28,239 NTU from 2006 to 2007 at Buaran WTP. Extremely high turbidity inhigh frequency makes purification processes extremely difficult. Therefore, three kinds of coagulantare used to combine the effects of each ones, and two kinds of polyelectrolyte are applied to makedense flocs. So it was difficult to derive the general formula that chemical concentration is related towater quality parameters. Instead turbidity removed was related to the combined effects of chemicals.Like the first formula as shown in Table 5.5, turbidity removal accomplished with the combinedaction of Alum, PAC, Sudofloc A and polyelectrolytes.

C. Water treatment cost


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We tried an empirical approach to develop a model that relates chemical cost per unit of treated waterto raw water quality. Costs/unit for each chemical are shown in Table 5.4. Water quality parameterssuch as turbidity, pH, organic matter and color of raw water which are available and considered toinfluence coagulation process were included in regression equations. As shown in Table 5.6, Cost perunit of treated water was related to the raw water turbidity and the R2 was not increased above 19.7%

by including more parameters. The first equation will be applied to the cost estimation of chemicalsused for water treatment.

Relation between chemical cost per 1000m3 treated and raw water quality

Regression equations R 2, Adjusted R2

Cost/1000m3 = 23.2 + 0.00464 Daily average

turbidity

R-Sq = 19.7% R-Sq(adj) =

19.6%

Cost/1000m3 = - 16.6 + 0.00331 Daily average

turbidity + 5.59 Daily average pH + 0.0414

Daily average organic matter + 0.0254 Daily

average color

R-Sq = 21.4% R-Sq(adj) =

21.2%


turbidity + 5.71 pH + 0.0347 Daily average

color

R-Sq = 20.4% R-Sq(adj) =

20.3%


turbidity + 5.59 Daily average pH + 0.0426

Daily average organic matter

R-Sq = 21.3% R-Sq(adj) =

21.2%

From Figure 5.14 which shows the raw water turbidity distribution at the Buaran WTP during theperiod 2006-2010, frequency of turbidity occurrence was estimated.

< Table 5.7>Yearly frequency of raw water turbidity at Buaran WTP

Turbidity, NTUFrequencyof dailyaverage

Frequency ofdaily maximum

0 ~ 300 298 253

300 ~ 1000 32 47

1000 ~3000 27 27

3000 ~ 10000 8 23

10000 ~ 14Table 5.8 shows chemical costs at Buaran WTP and all the WTPs which take raw water from WTC.As the turbidity of raw water is high, chemical costs are extremely high. In case of raw water turbidityimprovement to 300 NTU which is much higher than the average turbidity, 153 NTU at the Curugweir, yearly reduction in chemicals cost will be estimated using the equation for cost/1000m 3 in Table5.6 and yearly frequency exceeding 300 NTU in Table 5.7. In this case Buaran WTP can save 235,265US$ and 731,462 US$ for all the WTPs which use WTC water. If the turbidity of WTC water could

be reduced further, chemical costs could be saved more.

Chemical costs at the water treatment plants using raw water from WTC (in US $)


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Turbidityrange,NTU

Frequency

Turbidityapplied,NTU

Chemicalcost/1000m3

Chemicalcost atBuaranWTP

Chemicalcost for allWTPs usingWTC rawwater

0 ~ 300 298 150 23.90 3,383,903 10,520,862300 ~1000

32 65026.22 398,651 1,239,442

1000~3000

27 200032.48 416,731 1,295,656

3000 ~10000

8 650053.36 202,853 630,690

10000 ~ 19000 111.36Yearly chemical cost 4,402,139 13,686,650

Chemical cost savings for raw water turbidity decrease to 300 NTU at the watertreatment plants using raw water from WTC (in US $)

Turbidityrange, NTU

Frequency

Turbidityapplied,NTU

Chemicalcost/1000m3

Chemicalcost/1000m3 at 300NTU

Costreduction

Costreductionat BuaranWTP

Costreductionfor all WTPsusing WTCraw water

0 ~ 300 298 150 23.90 24.59

300 ~ 1000 32 650 26.22 24.59 1.62 24,695 76,780

1000 ~3000 27 2000 32.48 24.59 7.89 101,206 314,6593000 ~10000

8 650053.36 24.59 28.77 109,364 340,024

10000 ~ 19000 111.36 24.59 86.77Yearly chemical cost reduction 235,266 731,463

V.3.3 Feasibility Study on the construction of siphons

One of the solutions to reduce the turbidity value would be the perfect pre-sedimentation in additionto the Silt Trap located at the entrances of infow to the WTC. BCEOM has proposed silt removingfacilities at the silt trap site located at just outlet of the proposed Bekasi siphon, however, suchfacilities can remove only easily settling large particles but have limit in reducing turbidity. ForTurbidity reduction pre-sedimentation works should include (i) installation of movable scrapper (ii)use of proper quantity of chemicals including coagulant such as Poly Aluminum Chloride andAluminum Sulfate, and polymer as a coagulant aid. Even in this case dissolved pollutants cannot beremoved by pre-sedimentation.

The consultants will evaluate the present treatment process of WTPs which take raw water from thedownstream of WTC and analyze the use of chemicals and costs of water treatment to evaluate theeffect of improved water quality by siphon constructions.

Economic and financial feasibility study will be carried out for each separate bypass and for theoption of both bypasses implemented, considering the present and improved water quality of the


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WTC. Benefits will be determined from comparisons between the with-and-without project situations.

The main purpose of the river separation works is to prevent the polluted waters of three rivers,Bekasi, Cibeet, and Cikarang from directly entering to the West Tarum Canal. The siphon

construction at the confluence of Bekasi River is already in progress. The construction of other twosiphons is now under feasibility study. These works will therefore help to improve the quality of rawwater supply through the WTC to the treatment plants in Jakarta and to the other raw water users.

The benefits from decoupling the flows from polluted river flows are the savings in chemical

treatment cost. This can be determined by comparing the unit treatment costs of the Jakarta treatment

plants at different quality conditions. The difference in unit costs of present and improved quality

conditions will be considered as the direct benefit from the river flow separation works. There may be

other conceivable benefits but these are all difficult to quantify and not specifically considered.

A. K waters analysis of Cikarang and Bekasi siphons

K water analysed alternative scenarios for water quality management to improve water qualityconditions of WTC. Constructing siphon systems for the Cikarang and Bekasi River will improvewater quality of WTC downstream to reduce 12% of BOD concentration at the location of Buaranwater treatment plant. The water quality improvement of the Bekasi River by 20% BOD reductionyields 16.7% of BOD decrease at the same location. For the aspect of turbid reduction about 12%turbidity decrease was obtained due to siphon construction at the confluence of BukaseRiver with WTC.

Flowrates and BOD (March 21 2007)

BOD of the Bekasi River was lower than that of the WTC.

SimulatedBOD1.86

(a)

0

2

4

6

8

10

0 10 20 30 40 50 60 70

DistancefromtheCurugWeir (Km)

03-21-2007Simulated

MeasuredMeasuredBODupthejunctionwithBekasi (4.76mg/L)

SimulatedBODupthejunctionwith Bekasi(1.86mg/L)

(b)


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0

1

2

3

4

0 10 20 30 40 50 60 70

Distancefromthe CurugWeir (Km)

BaseCase

ALT1(Bekasi only)

ALT1(combined)

Siphon

Kwater

simulation

100%

separation

Bekasi & Cikarang

(c)

0

1

2

3

4

0 10 20 30 40 50 60 70

Distance from the Curug Weir (Km)

Base Case

ALT2(20%)

ALT2(40%)

ALT2(60%)

BOD Decrease

ofBekasi River Water

(d)

BOD simulation of water quality management alternatives by K water


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Flowrates and turbidity (June 12 2007)

(a)

0.0

30.0

60.0

90.0

120.0

150.0

180.0

0 10 20 30 40 50 60 70


Jun/12/07Simulated

Measured

(b)


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0.0

30.0

60.0

90.0

120.0

150.0

180.0

0 10 20 30 40 50 60 70

ury


Jun/12/07

Simulated ALT 4

Turbidity simulation with Bekasi siphon construction

K water

simulation

100%

separation

(c)

Turbidity simulation for the siphon construction at the confluence of BukasiRiver with WTC

K water used only one day data on March 21 2007 although the effectiveness of siphon should be

analyzed through the wet and dry seasons. Simulated BOD values do not fit well with measuredvalues (Figure 5.20 (b)). In fact, BOD (3.76 mg/L) of Bekasi River was lower than that (4.76 mg/L) ofWTC, however, K water used the simulated value of 1.86 mg/L as BOD up the confluence of Bekasiwith WTC, which was much lower than real BOD of Bekasi River.

Simulation assumes that WTC water flows through the siphon without mixing with Bekasi water, butis augmented with Bekasi water to satisfy the necessary quantity of water. Here 11.98 m3/s of Bekasiwater is mixed with 10.64m3/s of WTC water to make downstream WTC water to be 22.12m3/s. If thenecessary flow downstream of WTC is supplied from Curug weir with 100% separation of Bekasiwater from WTC, the effectiveness of Bekasi siphon would be increased to 43% as shown in Figure5.20 (c). Then the construction of siphon is more effective than the 20% BOD reduction of BekasiRiver water by the pollution control in the Bekasi River basin (Figure 5.20 (d)).

The effectiveness of the siphon construction for turbidity reduction could be explained in the sameway as shown Figure 5.21 showing more improvement than the simulation by K water.

On the whole, it can be said that effectiveness of siphons was underestimated

B. Analysis of alternatives for water quality management on WTC

With the construction of siphons at the confluences of Bekasi, Cibeet River and Cikarang River with

WTC, BOD and turbidity in the downstream of WTC can be maintained less than the levels of BODof 4.12mg/L (min; 1.15, max; 8.26) and turbidity of 153 NTU (min; 0.9, max;1,280, Q3; 198) at the


23/25

Curug weir by separating the flows from the Cibeet River and the Cikang River analyzing the waterqualities from 2005 to2010. The Bekasi siphon is now under construction and effects of two otherswill be analyzed.

Alternative-1: Cibeet Partition Wall and Siphon Construction

As previously mentioned, considerable amount of sediments are entering to the WTC especiallyduring the rainy season. Through the construction of partition wall and siphon, the turbid flow fromthe Cibeet River will be delivered directly to the Kedunggede irrigation canal through BTB23. Theimprovement of water quality in WTS is anticipated.

Alternative-2: Cikarang Siphon Construction

The Cikarang River flow is also polluted and contributions are remarkable. Cikarang siphonconstruction will be evaluated for the improvement of water quality of WTC.

Alternative-3: Cibeet Partition Wall and Siphon, and Cikarang Siphon Construction

The flow of Bekasi River is considered the most polluted, and an inverted siphon is now underconstruction to separate it from entering into WTC. The flows of Cibeet and Cikarang are also

polluted and contributions are remarkable. Both of Cibeet partition wall and siphon construction, and

Cikarang siphon construction will be evaluated for the improvement of water quality of WTC.

Measured water quality values are so scattered along WTC as shown in Figure 5.20 and Figure 5.21,and simulated values can never be fitted to those values. Therefore, variation of BOD and turbidityalong the WTC was estimated by a simple material balance method, not using a complicated modelsuch as QUAL2 type. Table 5.6 shows the procedure of calculating BOD and turbidity along WTC at

present and after the construction of Bekasi siphon. Calculations of other alternatives are not shown inTable 5.10. However, effects of alternatives for siphon construction in reducing BOD and turbidity atthe Buaran WTP intake were summarized in Table 5.11. Averages of water quality from 2005 to 2010were used even if there are inconsistencies in the data.

Variation of water qualities along WTC ((a) present, (b) after Bekasi siphon)

(a)

Flow intoWTC m3/s

WTC flowm3/s

BOD mg/LTurbidity NTU

From Curug 41.7 4.1 153.0

41.7 4.1 153.0

33.8 4.1 153.0

From Cibeet 10.2 4.8 338.043.9 4.3 195.7


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33.5 4.3 195.7FromCikarang

7.5 4.9 214.0

40.9 4.4 201.2

10.6 4.4 201.2

From Bekasi 7.1 4.8 489.0

Downstream 17.7 4.7 411.0

Kedunggede irrigation 10.5

Cibeet 29.2

Cikarang 14.3

Bekasi 28.4

(b)

Flow into WTCm3/s

WTC flowm3/s

BODmg/L

Turbidity NTU

From Curug 48.8 4.1 153.0

48.8 4.1 153.0

40.9 4.1 153.0

From Cibeet 10.2 4.8 338.0

51.1 4.3 189.8

40.6 4.3 189.8

From Cikarang 7.5 4.9 214.0

48.0 4.4 196.1

17.7 4.4 196.1

From Bekasi 0.0 4.8 489.0

Downstream 17.7 4.4 196.1

Kedunggede irrigation 10.5

Cibeet 29.2

Cikarang 14.3

Bekasi 28.4

Effects of siphons on water qualities at the Buaran WTP intake using water quality dataduring the period 2005-2010

AlternativesBOD atBuaran(mg/L)

BODreduction(%)

Turbidityat Buaran(NTU)

Turbidityreduction(%)

Present 4.73 411.0

Bekasi 4.41 6.70 196.1 52.3


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siphon

Bekasi &Cikarangsiphon

4.23 10.41 185.1 55.0

Bekasi &Cibeet siphon

4.31 8.75 168.9 58.9

Bekasi,Cikarang &Cibeet siphon

4.12 12.83 153.0 62.8

In case of using the averages from 1993 to 2010 with all available data from PJT II, summarizedresults are as shown in Table 5.12. Compared to the effects using recent water quality data (2005-2010), water quality at the Buaran WTP intake improved remarkably as more siphons are constructed.That is the reason why the previous studies recommended the construction of siphons at theconfluences of three rivers to prevent polluted river flows from entering into WTC. In both cases,Cikarang siphon is more effective in reducing BOD, while Cibeet siphon is more effective in reducingturbidity. As mentioned earlier, only available data provided by PJT II may be insufficient to justifythe unnecessariness of siphons in addition to Bekasi siphon. Based on that data, the water qualities ofthree rivers seem to be improved since 2005 as there are not much difference between them andWTC. However, it is difficult to assess the state of water quality in the rivers and WTC with onlymonthly measured data that sometimes is missing for months and sampled inconsistently. Turbidityvalues continuously measured by WTP at the Buaran WTP intake range from 16 to 3,465 NTU withaverage of 279 NTU, while those measured monthly by PJT II range from 16 to 3,465 with average of279 NTU. It shows the result that monthly measured data is not sufficient in representing the realsituation. Continuous water quality monitoring will be prerequisite to judge the necessity of more

siphons if recent data can have the credibility in being used for the feasibility. In addition it mustiangenclude synthetic organic micro pollutants, heavy metals and microorganisms that can be used toassess the sources of pollution such as industry, agriculture, population, etc.

Effects of siphons on water qualities at the Buaran WTP intake using water quality dataduring the period 1993-2010

AlternativesBOD atBuaran(mg/L)

BODreduction

(%)

Turbidityat Buaran

(NTU)

Turbidityreduction

(%)

Present 8.22 822.9

Bekasi siphon 6.53 20.5 624.7 24.1

Bekasi &Cikarangsiphon

5.70 30.7 504.4 38.7

Bekasi &Cibeet siphon

6.2 25.0 455.3 44.7

Bekasi,Cikarang &

Cibeet siphon5.26 36.0 304.5 63.0

Documents

WaterQuality Report