Application of Rapid Filtration Tank

for Stormwater and Wastewater Treatment

（Utilization of Existing Primary Stabilization Tank)

Masahiro FUJII

Water Environment Department, Sewerage Division,

Public Works Bureau, City of Osaka

Contents

1 Features of Osaka City’s Sewerage System

2 Background of the Survey

3 Brief Outline of Rapid Filtration Tank

4 Experimental Data

5 Conclusion

1 Features of Osaka City’s Sewerage System

Osaka

Tokyo

Outline of Sewage Works in Osaka City • Total population：

2.67million persons

• Area：222ｋｍ2

• Proportion of served by sewerage：99.9％

• Total sewer length：4,877km

• Pumping station：58

• Sewage treatment plant：12

• Total sewage treatment plants：2,844,000m3/ｄａｙ

・ Total drainge capacity

：1,330m3/s

Kobe

Osaka ｃｉｔｙ

Sewage Collection System

CSO outfall in

dry weather

CSO outfall in

wet weather

Combined sewer system area Separate sewer system area

■ Stormwater outfalls

Wastewater treatment plants (yard pump stations)

12 outfalls

Pump stations (pumping stations) 46 outfalls

Natural discharge points 56 outfalls

Total stormwater outfalls 114 outfalls

Kitano Pump stations

Higashiyokobori River

Yamato River

• 97％ is served combined sewer system in Osaka City

• Improvement of combined sewer system

2 Background of the Survey

Improvement measures of combined sewer system

• Application of Separate System ⇒Physically Impossible and Economically Inefficient

• Stormwater Storage (Stormwater Reservoirs)

⇒Difficult in Site Acquisition (Rapid Urbanization)

Continuous Stormwater Treatment

◎Wet Weather Activated Sludge Process

◎ Plate Settlers Sedimentation Process

Image of Wet Weather Sewage Treatment in Osaka City

３Qsh

１Qsh

２Qsh 簡易放流 Wet weather activated sludge process

Future Plan (After Application of Rapid Filtration System)

反応槽

終沈

３Qsh

初

沈 等

高速ろ過

３ W 法

３Ｑsh

Plate Settler

Sedimen tation

Rapid Filtration Facility 3Ｑsh

3Ｑsh

Space-saving by 70%

Install additional treatment devices for remaining area

Increase in treatment capacity

Reduction in direct discharge

Temporary storage

Direct discharge

Plate settler sedimentation with coagulant addition

Final Sedimen

tation Tanks

Wet Weather Activated

Sludge Process

(for 3Qsh)

Exceeding 6Qsh (Direct discharge)

Time

Infu

ent

fro

w

3 Brief Outline of Rapid Filtration Tank

Rapid Filtration Facility

Testing Facility (Dismantled facility)

Pilot Plant

Plain View of

Chishima

Sewage

Treatment Plant

discharge to Kizu River

Kizu River

Influent

Trunk

sewer

Final

Settling

Tanks

Reaction

Tanks

Water

reclamation

facility

Mechanical

Equipment Room

Pre-aeration

Tanks

Rapid

Filtration

Facility

Primary

Settling

Tanks

Pump

Room

No.3

Grit

chamber

No.3

Trunk

sewer

Sludge

Pump Room

Reclaimed

Water

Seseraginosato

(garden with an

artificial stream)

Pre-treatment

facility for

sludge

transportation

Sludge transportation pipe (to

Tsumori Sewage Treatment Plant)

Tennis

courts

Primary Settling Tank Plan View

Drainage Tank

Rapid Filtration

Facility（First stage ）

Distribution

Tank

Rapid Filtration

Facility（Future ）

Rapid Filtration Facility Plan view

Sedimentation Tank

Primary Settling Tank Section View

Rapid Filtration Facility Section view

Rapid Filtration

Facility（First stage ）

Filtered water

Upper screen

Raw water

Distribution tank

Lifting pump

Cleaning wastewater tank

Filter media layer

Treatment Flow of Rapid Filtration Tank

Filter media 7.5mm×7.5ｍｍ×4ｍｍ

Material Special Polymer Material

Principle of Filtration and Cleaning

Filtration Cleaning Screen is

installed upper

part of the Tank

Floating Filter

Media

Floating

Filter

Media

Removal Upflow Downflow

Filtrate

water

(Debris)

・Hair

・Kitchen waste

・Leaves

・Oil ball .etc

Effluent

after

cleaning

the filter

media

Debris・ SS

4 Experimental Data

practical research equipment

（Study duration：2003.1～2005.6）

Wet Weather SS・BOD Removal Rate Data (Practical research equipment)

Target Removal Rate of 30% was achieved (SS・BOD).

0

10

20

30

40

50

60

70

80

90

100

0 300 600 900 1200 1500

Ｉｎｆｒｏｗ SS （ｍｇ/L）

Ｒｅｍｏｖａｌ Ｒａｔｅ（％）

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：600ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：800ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：1000ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：1200ｍ/ｄ

0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200

Ｉｎｆｒｏｗ BOD （ｍｇ/L） Ｒｅｍｏｖａｌ Ｒａｔｅ（％

）

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：600ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：800ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：1000ｍ/ｄ Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ：1200ｍ/ｄ

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

SS除去率

（％

）

Primary Settling Tank 23m/d

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ 300m/d

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ 500m/d

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

BO

D除去率

（％

）

Primary Settling Tank 23m/d

Dry Weather SS・BOD Removal Rate Data (Practical research equipment)

SS ： Target removal rate of 45% is achieved in case inflow SS concentration is over 40mg/L(better than the removal rate of existing primary sedimentation tanks).

BOD： Target removal rate of 35% is almost achieved in case inflow BOD concentration

is over 100mg/L(equivalent to the removal rate of existing primary sedimentation tanks).

Ｉｎｆｒｏｗ SS （ｍｇ/L）

Ｒｅｍｏｖａｌ Ｒａｔｅ（％）

Ｉｎｆｒｏｗ BOD （ｍｇ/L)

Ｒｅｍｏｖａｌ Ｒａｔｅ（％

）

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ 300m/d

Ｆｉｌｔｒａｔｉｏｎ Ｒａｔｅ 500m/d

Demonstration facility （First stage construction：2009.4～2011.3）

（Study period：2009.4～2011.3）

Evaluation Standards

Items

Study for the Practical Use

of the Rapid Filtration Performance assessment

study

Dry

weather

Wet

weather

Dry

weather

Wet

weather

Total

Filtration rate (m/day) 500 1,200 340、500 800 －

Raw water SS concentrations (mg/L)

over 80 － over 80 － －

Raw water BOD concentrations (mg/L)

over 120 － over 120 － －

SS removal rate over45% over30% over45% over30% over30%

BOD removal rate over35% over30% over35% over30% over30%

Debris removal

rate 100% 100% 100% 100% －

Flow Diagram of the Proving Test Facility

P P

Primary

Settling Tank

Inflow

Ｓｅｄｉｍｅnｔａｔｉｏｎ

tank Drainage Tank

Rapid Filtration Tank

Distribution

Tank

Reaction

Tanks

Raw

Water Pump

36m3/min×3units P

M

Effluent after

cleaning the

filtermedia

Flow Regulating

Valve (1)

Effluent after cleaning the

filtermedia

Flow Regulating Valve (2)

P

Sludge

Treatment

Facility

F

SS

SS

Δ P

F C

F

C

SS

水位

水位

Capacity Tank

：400m3

Filtration Area：123m2

(30.75 m2×4Parts)

Pump for the

effluent after

cleaning the filter

media

25m3/min×2units Sludge removal pump:1.7m3/min×2units

Flow Meter

Water Level

min units

Analysis Item and Sampling Interval

<Analysis items>

Raw water

Filtrate water ：SS, BOD, Soluble BOD*、Debris

Surpernat *Dry Weather Filtration Rate: 340m/day

Back Washed-water ：SS, Debris

<Water sampling interval>

Dry weather: every 2 hours(10：00～8：00 on next day)⇒ total 12 samples

Wet weather: every 15 minutes during first 90minutes and every 5 hours until 24hors after 90 minutes⇒ total 12 samples

Number of Experiments

• Dry weather total 6 times

Filtration rate 340m/day・・・3times

Filtration rate 500m/day・・・3times

• Wet weather total 4 times

Filtration rate 800m/day・・・2times

Filtration rate 1,200m/day・・・2times

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350

Inflow BOD（mg/L）

Rem

oval R

ate（%）

Filtration Rate 800m/dFiltration Rate 1,200m/d

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350

Inflow SS （mg/L）

Rem

ovalR

ate（%）

Filtration Rate 800m/dFiltration Rate 1,200m/d

Wet Weather SS・BOD Removal Rate Data (Demonstration facility)

Target Removal Rate of 30% was almost achieved (SS・BOD).

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200 220 240

Inflow BOD（mg/L）

Rem

oval R

ate（%）

Inflow Rate 340m/dInflow Rate 500m/d

Performance Valuation Point：120mg/L

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120

Inflow SS（mg/L）

Rem

oval R

ate（%）

Filtration Rate 340m/dFiltration Rate 500m/d

Performance Valuation Point：80mg/L

Dry Weather SS・BOD Removal Rate Data (Demonstration facility)

SS : Target Removal Rate of 30% was almost achieved (SS・BOD).

BOD：Removal rate(20-30%)in case inflow BOD concentration is over

120mg/L is equivalent to the removal rate of existing primary

sedimentation tanks.

Experiment in

Dry Weather

Filtration

Rate

Inflow

Soluble

BOD

(Average)

Inflow

Solid

BOD

(Average)

Soluble

BOD

Removal

Rate

Solid

BOD

Removal

Rate

Total BOD

Removal

Rate

SS

Removal

Rate

m/d mg/L mg/L ％ ％ ％ ％

NO.1 340 36 34 13 33 23 51

NO.2 500 47 63 7 32 21 45

NO.3 340 39 72 26 51 43 57

NO.4 500 80 81 11 48 29 49

NO.5 340 78 57 12 59 32 61

NO.6 500 93 67 8 48 24 54

Removal rate of S-BOD

Removal rate of S-BOD was low but equivalent to that of existing

primary stabilization tanks(24%).

Debris removal rate

• Removal rate is achieved almost 100% both in dry and wet

weather.

Filtation rate

Wet weather debris removal

rate

m/day %

No.1 800 100

No.2 800 100

No.3 1200 98

No.4 1200 100

Filtation rate

Dry weather debris removal

rate

m/day %

No.1 340 100

No.2 500 100

No.3 340 100

No.4 500 100

No.5 340 100

No.6 500 100

Condition of Filter Media(attrition rate)

Basic dimension

(mm)

Ｎｏ．１ (Average) 2010.3.11

Ｎｏ．２(Average) 2010.11.2

Remarks

Upper layer Under layer Upper layer Under layer Unit

Thickness of filter media

mm/10Pieces

40.00 38.76 38.74 39.36 38.76

Quality control value

40±5mm/10Pieces

% 100 96.9 96.9 98.4 96.9

External dimensions(

mm/10Pieces

7.50 7.25 7.35 7.34 7.11

% 100 96.6 98.0 97.9 94.8

Condition of Filter Media(attached extraneous matter)

Ｎｏ．１ (Average) 2010.3.11

Ｎｏ．２(Average) 2010.11.2

Unit Upper layer Under layer Upper layer Under layer

Total weight of filter media

① － ｇ/50Piece 1.1250

total weight of attached extraneous matter

② － ｇ/50Piece

0.1878 0.1560 0.1822 0.1589

total weight of attached extraneous matter/Total weight of filter media

③ ②/①

% 17 14 16 14

weight of attached fat ④ mg/50Piece 21 17 11 13

weight of attached fat /Total weight of filter media

⑤ ④/（①×1000） % 1.87 1.51 0.96 1.16

weight of attached fat/total weight of attached extraneous matter

⑥ ④/（②×1000） % 11.2 10.9 5.9 8.2

2012.2.9～10

Conclusion

1 Rapid Filtration’s Removal Rate of SS and Debris

The target performance level was achieved both in wet and dry

weather.

2 Rapid Filtration’s Removal Rate of BOD

The target performance level was achieved in wet weather.

3 Rapid Filtration’s BOD removal rate BOD removal rate in dry weather is equivalent to that of

conventional primary sedimentation tanks because S-BOD removal

rate is relatively low.

Thank you very much

for listening

• This presentation was made on the 4th EWA/WEF/JSWA Specialty Conference in Kobe, July 26-27, 2012.

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