2011/11/30

Workshop 4, Session 2
Wastewater Management to Support River Basin Water Quality

POTENTIAL OF SMALL SCALE AND
LARGE SCALE SOLUTIONS –COST AND QUALITY ASPECTSW ednesday 23 November 2011

Pierre Flamand1

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CHARACTERISTICS OF THE MAJOR WASTEWATER TREATMENT SYSTEMS IN JAPANCategory & type ofsystem

Sewerage system
Centralized System

Rural sewerage system
Centralized system (small-scale)

Johkasou system
Decentralized system

Purpose-Treat industrial, miscellaneous
domestic WWT & stormwater-Prevent inundation-Maintain quality of water
resources-Protect public health-Treat miscellaneous domestic
WWT & stormwater-Prevent inundation-Maintain quality of water
resources-Protect public health-Treat domestic & miscellaneous
WWT-Maintain quality of water
resources-Protect public health

Suitable areas

Mainly urban, peri-urban areas

Agricultural villages within
selected areas where agriculture
is promoted

Peri-urban, rural areas
where sewerage system is notplannedAdministrator for
installation, O&M

Municipalities

Municipalities
and selected areas whereagriculture is promoted

Individuals, communities andmunicipalities

Applicable
population

10,000 people or more

Up to 1,000 peopleSmall-scale = 5 to 50 people(less than 10 m³/day)
Medium-scale = 51 to 500 people(less than 100 m³/day)
Large-scale = more than 500 people(more than 100 m³/day)

Legal

Treatment plants: 23 years
Piping system: 50 years-7 years

Past
results

Treatment plant: 15-70 years
Piping system: 50-120 years-Main body: over 30 years
Equipment: 7-15 years

Construction period

Approx. 5 years

3-5 years

Approx. 1 week to 1 year

Served population(as of 2009)93.6 million (73.7%)

3.79 million (3.0%)

11.24 million (8.8%)

Lifecycle2

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ADVANTAGES AND SPECIFICITIES OF JOHKASOU— Flexible system that can cope with population decrease— Less vulnerable to earthquakes and other disasters— Cheaper and quicker to put in service after disaster occurrence— Low initial investment cost, high treatment performance— Little topographic limitation, short installation time and quick results— Invaluable contribution to maintaining sufficient water in small rivers

and aquatic environments near inhabited areas— Treated effluent and sludge are easy to reuse

Percentage, %10090807060504030
20100(as of the end of FY 2007)
99.2

88.9

87.1

82.7

75.5
67.6

Sum of major domestic wastewater treatment systems

0.6

6.2

More than 500-1,000
1,000

7.2

9.6

300-500

100-300

16.4

13.7

Johkasou system
50-100Less than50

Size of municipalities, thousand

decentralized system

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decentralized system

SMALL-SCALE JOHKASOU (FRP)

Conventional johkasou (FRP-made)Capacity = 5 to 50 users

Membrane johkasou

Effluent quality
BOD <=20 mg/l

Johkasou for BOD, N&P Removal

Effluent quality
BOD <= 5 mg/l
T-N <=10 mg/l
Effluent quality
BOD <=10 mg/l
T-N <=10 mg/l
T-P <= 1 mg/l

decentralized system

MEDIUM-SCALE JOHKASOU (FRP-made)Capacity = 51 to 500 users

LARGE-SCALE JOHKASOU (RC-made)Capacity = more than 500 users

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MAIN SYSTEMS FOR WASTEWATER TREATMENT

DECENTRALIZED & CENTRALIZED WASTEWATER TREATMENTSYSTEMS: ADVANTAGES / DISADVANTAGES AND IMPACTS

Items

Advantagesof decentralized systems

Advantagesof centralized systems

Number of HHsmallbigDistance between
HH（in meters）

Longshort

Soil undulationand number ofwater bodies

bigsmall5

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DETERMINATION OF CENTRALIZED AND DECENTRALIZED AREAS

Decentralized system (johkasou)

Centralized treatment

Selection Criterion
Step1: pre-grouping

×more than 20 Households

×less than 20 Households

within 80 m

over 80 m

11DETERMINATION OF CENTRALIZED AND DECENTRALIZED AREAS
Step1: pre-grouping

18 Households (HH)

Decentralized

over 80 m
80 HH

10 HH

Centralized

Decentralized

50 m
80 HH

10 HH

Centralized126

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Step 2: Selection for centralized & decentralized systems
Example: 160 Households,
Total pipe Length > 8513m à decentralized
Total of pipe Length < 8513m à centralized
Decision making factor : cost

160 HH

Pipe = 500 m
160 HH Pipe = 9000 m

Centralized system

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Decentralized system

Step3: Connection of Off-site treatment districts
1500 m180 Households (HH)

200 HH

Decision making factor : cost

200 HH180 HH

Pump

Pipe (1500m)

180 HHPump

200 HH
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COST COMPARISON FOR SELECTION
OF WASTEWATER TREATMENT SYSTEM
GENERAL CONDITIONS:TYPE 1:

Number of households (HH) in targeted area → 110
Targeted population → 418 people

sewerage system(Utilization of existing treatment plant)

Specific Conditions:
Extension of sewer network Length = 3,000 m
Manholes/pumps Number = 2(when connecting to already existing sewered area)
Targeted area

Existing
sewered area

Centralizedsystem

Cost for 34 years = 1,050 million yen- Revenue in 34 years = 421 million yen= Total cost in 34 years = 629 million yen

Installed sewer pipes

Treatment plant

Planned sewer pipes

COST COMPARISON FOR SELECTION
OF WASTEWATER TREATMENT SYSTEM
GENERAL CONDITIONS:TYPE 2:

Number of households (HH) in targeted area → 110
Targeted population → 418 people

sewerage system(Construction of a new treatment plant)

Specific Conditions:
Extension of sewer network Length = 2,500 m
Manholes/pumps Number = 2
WWT Treatment Plant Number = 1(when not connecting to already existing sewered area)
Targeted area
Existing
sewered area

Treatment Plant

Cost for 34 years = 1,082 million yen- Revenue in 34 years = 377 million yen= Total cost in 34 years = 705 million yen

Centralized system

Treatment plantInstalled sewer pipes
Planned sewer pipes

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COST COMPARISON FOR SELECTION
OF WASTEWATER TREATMENT SYSTEM
GENERAL CONDITIONS:TYPE 3:

Number of households (HH) in targeted area → 110
Targeted population → 418 people

Implementation of johkasou by municipalities

Specific Conditions:Johkasou units = 110(when not connecting to already existing sewered area)
Targeted areac
Existing
sewered area

Cost for 34 years = 833 million yen

Decentralized system- Revenue in 34 years = 292 million yen= Total cost in 34 years = 541 million yen
Treatment plant

Cost-effective& best solution

Installed sewer pipes

MASTER PLAN FOR WWT TREATMENT
IN SAGA PREFECTURE

LEGEND
SEWERAGE SYSTEM
公共下水道
整 備 手 法特環公共下水道RURAL SEWERAGESYSTEM

農業集落排水漁業集落排水合併処理浄化槽

JOHKASOU

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COST COMPARISON BETWEEN CENTRALIZED SYSTEMSAND DECENTRALIZED SYSTEMS
Cost per Capita(including construction and maintenance costs)

Equilibrium point
Decentralized system

Centralized system

Population density

BOD5 or CODMn

WATER QUALITY IN WATER BODIES IN JAPANRivers
LakesSeas1980

1983

1986

1989

1992

1995

1998

2001

20042007

Years
Note: Rivers = BOD; Lakes and seas = COD

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CONCLUSION

In the case of Japan,
To improve water quality, centralized and decentralized
systems were developed to achieve equivalent
wastewater treatment quality
A combination of both systems proved to be cost-effective
and the best way to increase sanitation coverage in a
relatively short period of time

p The Japan Sanitation Consortium (JSC) was launched on 16 October 2009
p JSC consists of the 4 main national agencies managing on-site and offsite sanitation in Japan
p JSC aims to utilize Japan’s advanced experience in sanitation and successfulmodels from other countries to solve related issues in the regionl JSC collaborates with ADB andother Donors Agencies, internationalorganizations, NGOs, etc. forregional sanitation improvementl JSC MEMBER ORGANIZATIONS
Off-site Sanitation
Sewerage Business Management Centre
Japan Sewage Works Association
On-site Sanitation
On-site Sanitation
Japan Environmental Sanitation Center
Japan Environmental Sanitation Center
Japan Education Center of Environmental Sanitation
Japan Education Center ofEnvironmental Sanitation11

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JSC Sanitation KnowledgeHub, Japan
Regional Water Knowledge Hub for SanitationJSC Expertise— Member of a regional network of water specialists, commi tted for sanitation developmentin the Asia-Pacific region— On-site and off-site sanitation specialized organization
JSC Services— Networking, Information Gathering & Sharing, Knowledge Dissemination, Support toInternational Donor Organizations
JSC Partners— ADB, JICA, Japan Water Forum, UNICEF, etc.

Thank you for your attention

e-mail: info@jsanic.org
www.jsanic.org

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