SmallSmall--Scale Domestic Wastewater Treatment Scale Domestic Wastewater Treatment Technology in Japan, and the Possibility of Technology in Japan, and the Possibility of

Technological TransferTechnological Transfer

Motoyuki MIZUOCHIMotoyuki MIZUOCHIAsian Environment Research GroupAsian Environment Research Group

National Institute for Environmental StudiesNational Institute for Environmental Studies

The importance of small scale domestic wastewater The importance of small scale domestic wastewater treatment technologytreatment technology

There is a trend in domestic wastewater treatment in which largeThere is a trend in domestic wastewater treatment in which large city areas city areas are accommodated more readily than medium and small city areas, are accommodated more readily than medium and small city areas, or rural or rural communities.communities.

““Locally suitable technologyLocally suitable technology”” that is adaptable to local social and that is adaptable to local social and economic conditions is sought in developing countries, but it iseconomic conditions is sought in developing countries, but it is difficult to difficult to transfer the general Japanese technological system without modiftransfer the general Japanese technological system without modification.ication.

Low cost system for construction and maintenance is needed.Low cost system for construction and maintenance is needed.

This report gives an overview of JapanThis report gives an overview of Japan’’s domestic wastewater treatment and s domestic wastewater treatment and smallsmall--scale treatment technology, and discusses cases of technologicalscale treatment technology, and discusses cases of technologicalsystems that are highly likely to be transferredsystems that are highly likely to be transferred referred to technology development trend in China and example of technical transfer from Japan.

Classification of domestic wastewaterClassification of domestic wastewater

BathBath

KitchenKitchen

Wash basinWash basin

Washing machineWashing machine

ToiletToilet

Gray waterGray water

Night soilNight soil

Domestic Domestic wastewaterwastewater

Gray waterDomestic wastewaterNight soilSludgeGray water Night soilEffluent

Treatment system

Municipal sewerage

Sludge treatment system

IncinerationReuse

Vault toilet

Public water area Land fill site

Rural community sewerage

On site system

The flow diagram of domestic wastewater treatment in JapanThe flow diagram of domestic wastewater treatment in Japan

Night soil TP

農村集落排水処理

事業,352, 3%

合併処理浄化槽,1128, 9%

くみ取り,1474,12%

単独処理浄化槽,953, 7%

下水道,8802,69%

The outline of domestic wastewater treatment situation in Japan（2005 Unit：million person）

On site sewerage only for night soil

On site sewerage

Rural community sewerage Municipal sewerage

Vault toilet

2,427 million person2,427 million person’’s (19% of the total population) gray water was s (19% of the total population) gray water was discharged without any treatment in Japan at the end of discharged without any treatment in Japan at the end of 20052005..

Representative small scale domestic wastewater Representative small scale domestic wastewater treatment technologytreatment technology

■■AerobicAerobic●●Sludge suspensionSludge suspension Oxidation ditchOxidation ditch●●BiofilmBiofilm Contact aeration Contact aeration （（JhokasoJhokaso））

Rotating biological contactorRotating biological contactorTrickling filterTrickling filter

●●Natural treatmentNatural treatment Soil trenchSoil trench・・Constructed wetlandConstructed wetland

■■AnaerobicAnaerobic●●Septic tankSeptic tank・・Imhoff tankImhoff tank

■■Vault toilet (Storage)Vault toilet (Storage)●●Only StorageOnly Storage Pit latrinesPit latrines●●UtilizationUtilization Double vault latrinesDouble vault latrines

Compost latrinesCompost latrinesBiogas plantBiogas plant

99.187.6 86.1

81.473.5

65.5

0

20

40

60

80

100

120

More than1,000,000

500,000～1,000,00

300,000～500,000

100,000～300,000

50,000～100,000

Less than50,000

Scale of the population

Covera

ge r

ate

(%)

Number of Cities, towns and villages

Covered population

Totalpopulation

12

2,710

2,734

1,2632811894515

1,4411,4362,4801,496905

2,1991,9553,0461,7381,033

Unit of population: million

The coverage rate of domestic wastewater treatment in The coverage rate of domestic wastewater treatment in areas with a population scale at the end of 2006 in Japan areas with a population scale at the end of 2006 in Japan

30Extended aeration

1Step aeration87Contact aeration65SBR

13Rotating biological contactor4Others

Number of WWTPProcess

1,049Total

784Oxidation ditch43Conventional activated sludge22Nutrient removal (Activated sludge)

The number of The number of Municipal WWTP less than 5,000mMunicipal WWTP less than 5,000m33/day/day according according to the kindto the kind of treatment process at the end of 2004 in Japan of treatment process at the end of 2004 in Japan

Oxidation ditch process excelled in WWPT less than 5,000m3/day

Small scale municipal sewerageSmall scale municipal sewerage

Oxidation ditch processOxidation ditch process

With respect to sewage facilities, 1,049 small-scale treatment facilities capable of treating 5,000 m3 or less of water per day were in operation at the end of FY 2004, and 70% of sewage facilities adopted the oxidation ditch process.

Though the oxidation ditch process is advantageous in terms of maintenance because primary sedimentation tanks are unnecessary, the treatment and disposal of the large volume of sludge generated becomes a major issue.

Johkaso is an on-site treatment facility that has been technologically developed uniquely in Japan. In Japan, human waste was treated as manure for a long period of time, however, because chemical fertilizers were popularized after World War II to the high economic growth period, and there was an increasing demand for flush toilets, on-site treatment facilities without the need for pipes became widespread.

Johkaso for 5-10 persons (individual house)

Johkaso for 14-50 persons (apartment, public place, etc.)

Johkaso system in JapanJohkaso system in Japan

Type of Johkaso (Type of Johkaso (TandokuTandoku and and GappeiGappei))

Gappei

Tandoku

Gappei Johkaso treats night soil and gray water together same as municipal sewerage.

Tandoku Johkaso treats only night soil . In this case, gray water is discharged without treatment.

This type of Johkaso was supposed to be allowed to be used until 2001, but many of them are still being used now.

Rural community sewerage(Agricultural community wastewater treatment programs)

Agricultural community wastewater treatment programs are intended to provide domestic wastewater treatment facilities for a single or multiple rural communities where domestic wastewater treatment facilities have not been sufficiently provided.

A treatment process is being indicated in stages for the treated population of from 51 to 10,000 (JARUS type)

51～2,000

501～10,000

1,000～10,000

Contact aeration

Oxidation ditch

SBR

One of Japanese technical trendOne of Japanese technical trend：：SSoil covered gravel contact aeration processoil covered gravel contact aeration process

BackgroundBackground：：Low cost system for construction and maintenance by Low cost system for construction and maintenance by local governments overseeing sewerage services and local governments overseeing sewerage services and facing more difficult financial conditions.facing more difficult financial conditions.

CCharacteristicharacteristic::IIt can be designed in response to the varied t can be designed in response to the varied size of the treated populationsize of the treated population by relatively by relatively simple structure.simple structure.

PProducing almost no odor from the roducing almost no odor from the treatment facilities because the tops of the treatment facilities because the tops of the treatment facilities are covered with soil.treatment facilities are covered with soil.

Lower sludge generation

This process was developed 25 yearsThis process was developed 25 years ago, ago, and it and it has recently been adopted for sewage has recently been adopted for sewage treatment facilities.treatment facilities.

Same local government has been selected this system for small scSame local government has been selected this system for small scale ale municipal sewerage WWTP municipal sewerage WWTP

This system is designed for small scale domestic This system is designed for small scale domestic wastewater treatment against the activated sludge wastewater treatment against the activated sludge process family based on the contact aeration process. process family based on the contact aeration process.

This system require relatively larger land area than the This system require relatively larger land area than the activated sludge process family like the oxidation ditch activated sludge process family like the oxidation ditch process. But this system has highly economic value.process. But this system has highly economic value.

““Contact aeration process using gravel with covered the Contact aeration process using gravel with covered the top in the soiltop in the soil””

This is not new process, but is a reevaluated process in This is not new process, but is a reevaluated process in now for small scale system like sub hundreds cubic now for small scale system like sub hundreds cubic meters sewage scale. meters sewage scale.

SSoil covered gravel contact aeration processoil covered gravel contact aeration process

Cross section of the soil covered gravel contact Cross section of the soil covered gravel contact aeration processaeration process

An actual constructive stateAn actual constructive state

IkiIki--city (Nagasaki pref.) Wastewater Treatment Plant city (Nagasaki pref.) Wastewater Treatment Plant

Capacity: 640m3/dayCapacity: 640m3/day

A construction exampleA construction example：：On site facility for 50 On site facility for 50 personnspersonns

Adaptation to the middle scale Adaptation to the middle scale on site facility (200on site facility (200--300 persons)300 persons)

Condition of trial run and Condition of trial run and adjustment adjustment after the end of after the end of the constructionthe construction

・・Johkaso systemJohkaso system--Factory production Factory production typetype--JICAJICA Lake Taifu water quality restoration projectLake Taifu water quality restoration project（（China China 20012001--20052005））

MOE MOE GuizhouGuizhou Province water environment protection cooperation projectProvince water environment protection cooperation project（（China China 20002000））

--On site Construction typeOn site Construction type--JICWJICWELELSS Johkaso system introduction project (Indonesia 1995Johkaso system introduction project (Indonesia 1995--1996)1996)

・・Soil treatment systemSoil treatment system--Nutrient removal type soil trench systemNutrient removal type soil trench system--MOE MOE GuizhouGuizhou Province water environment protection cooperation projectProvince water environment protection cooperation project（（China China 20002000））

--Multi soil layer systemMulti soil layer system--JICAJICA grassgrass--roots projectroots project （（NPO Green Earth Network NPO Green Earth Network 20032003））

Example of technical transfer related small scale treatment Example of technical transfer related small scale treatment system from Japan system from Japan led by Chinaled by China

JICAJICA Lake Taifu water quality restoration projectLake Taifu water quality restoration projectFactory production Factory production typetype

MOE MOE GuizhouGuizhou Province water environment protection cooperation projectProvince water environment protection cooperation project

Problems of factory production type Johkaso technology Problems of factory production type Johkaso technology transfer in Chinatransfer in China

Grasp of the situation around Johkaso in China was insufficient.

Grasp of demonstration effect compared with social situation in China was insufficient.

Possibility of the adaptation of Johkasou in Japanwas not examined.

Examination of the structure matched with the Chinese situation is short.

Feasibility of the maintenance was not examined enough.

Rippled effect of technical transfer was insufficientRippled effect of technical transfer was insufficient

Chinese Jhokaso

Technical transfer of the on site construction type JohkasoTechnical transfer of the on site construction type JohkasoJapan International Corporation of Welfare ServicesJapan International Corporation of Welfare Services （（JICWELSJICWELS））

Indonesia Indonesia 19951995～～19961996

In Japan, Johkaso used to be mainly on site constructed, but they have been replaced dominantly by factory-produced Johkaso made of FRP due to soaring labor costs, and in order to secure the performance of Johkaso.

Because labor costs are not so high in many developing countries, a method with a higher percentage for labor costs for the provision of Johkaso becomes advantageous to lower construction costs.

It is thought that the technological transfer of field construction technology for Johkaso should be continuously stressed in the future.

Land treatment facilityLand treatment facility：：Nutrient removal type soil trenchNutrient removal type soil trenchMOE MOE GuizhouGuizhou Province water environment protection cooperation projectProvince water environment protection cooperation project

Plastic sheet

Soil for treatment

Plastic sheet

GravelEffluent collection pipe

Base soil

Sand

MatTrench pipeGravel

Air supply pipe

Plastic sheet

Soil for treatment

Plastic sheet

GravelEffluent collection pipe

Base soil

Sand

MatTrench pipeGravel

Air supply pipe

Plastic sheet

Soil for treatment

Plastic sheet

GravelEffluent collection pipe

Base soil

Sand

MatTrench pipeGravel

Air supply pipe

Characteristic ：■Energy consumption is extremely low.■ Construction is not needed high

technique.■ Cost for construction and

maintenance is low.■ The system principally has a

clogging problem.

%40Influent

60%

EffluentSoil trench （Reuse）

Soil trenchSeptic tank

Septic tank1st Unit2nd Unit

Nutrient removal type soil trench system installed in Nutrient removal type soil trench system installed in Guiyang city (Sports training center)Guiyang city (Sports training center)

CapacityCapacity：：30m30m33//dayday

Effluent

Over flow

JICAJICA grassgrass--roots project roots project （（NPO Green Earth NetworkNPO Green Earth Network））

Capacity : 250m3/day

Treatment principal is almost same as the soil trench system.

It was developed as a countermeasure for clogging and it is designed to treat wastewater by filtering the water through highly permeable pumice stone between soil layers

Land treatment facilityLand treatment facility：：Multi soil layer type systemMulti soil layer type system

Unit: m

10.0

10.0 2.0 1.0 6.4 1.0 5.0

沈殿池ろ過槽

流量調整槽 ポンプ槽

貯留槽高度処理槽

オーバーフロー導水路 既設水路

28．2（内寸25.4)

P

P P

Influent

Sedimentation tank

Filtration tank

Aeration

Flow equivalent

tank

Multi soil layered tank

Effluent tank

Reuse for irrigation

P

P P

Influent

Sedimentation tank

Filtration tank

Aeration

Flow equivalent

tank

Multi soil layered tank

Effluent tank

Reuse for irrigation

Multi soil layer system installed in Multi soil layer system installed in Datong CityDatong City

Influent EffluentInfluentInfluent EffluentEffluent1818110110CODcrCODcr

EffluentEffluentInfluentInfluent

Inner condition of MSLInner condition of MSL

MSL system is used as water reuse toilet for a nature MSL system is used as water reuse toilet for a nature conservatconservationion areaarea in Japanin Japan

Development of domestic wastewater treatment system Development of domestic wastewater treatment system for agricultural area in Chinafor agricultural area in China

Trickling FilterTrickling Filter

Rotating Biological ContactorRotating Biological Contactor

Horizontal oxidationHorizontal oxidation

Combination of Lagoon Combination of Lagoon and wetlandand wetland

LagoonLagoon

WetlandWetland

Ideal Way of Technological TransferIdeal Way of Technological Transfer (1)

Wastewater treatment technology changes according Wastewater treatment technology changes according to social conditions, and takes the most suitable to social conditions, and takes the most suitable form for a society that uses the technology, apart form for a society that uses the technology, apart from its basic elements.from its basic elements.

Therefore, when the technology is transferred to Therefore, when the technology is transferred to another society, it is necessary to examine its another society, it is necessary to examine its adaptability from various aspects.adaptability from various aspects.

Ideal Way of Technological TransferIdeal Way of Technological Transfer (2)

The difficulty in transferring Japanese technology to The difficulty in transferring Japanese technology to developing countries without modification is widely developing countries without modification is widely known.known.

Therefore, in order to consider future technological Therefore, in order to consider future technological transfer, it is necessary to not only consider current transfer, it is necessary to not only consider current technology but also to technology but also to look into previously developed look into previously developed or adopted technologyor adopted technology, and to evaluate it from current , and to evaluate it from current technological or economic standpoints.technological or economic standpoints.

図面名称

担当 製図 承認 製　作 訂　正株式会社環境開発茨城県つくば市北中妻215- 1

URL ht tp://ho mepage3 .nifty .com/kankyoukaihatu/E-ma il UG K11664@nifty.com

２階タンク

散水ピット槽

土壌式循環接触曝気槽

排泥ポンプ槽

分水ピット槽

250 4,000 250 1,200 250

5,950

250

1,000

250

800

250

5,500

250

800

250

9,350

原水ポンプ槽

ON

OFF

警報 警報

OFF

ON

15050250

2,000

150

300

2,900

250 1,200 250250 4,000

5,950

工事名称

平面図・断面図

断面図

平面図

縮　尺

1:30酒寄

酒寄

放流ポンプ槽

スクリーン

スクリーン

原水ポンプ槽

ＧＬ

流入 土壌式トレンチへ放流

土壌式トレンチへ放流

放流ポンプ槽

曝気エジェクター

散水濾床槽

散水管

取手市立さくら荘浄化槽

分配桝

Imhoff tank（Septic tank）

Trickling filter

Gravel contact aeration tank

Septic tank Trickling filter Gravel contact aeration tank

Soil trench

The facility installed The facility installed 2525 years ago: Effluent water quality is still satisfiedyears ago: Effluent water quality is still satisfied

InfluentInfluent

Trickling filterTrickling filter

EffluentEffluent

Because technology is not stationary, but constantly Because technology is not stationary, but constantly transforms according to the situation at the site where the transforms according to the situation at the site where the technology is needed, it is possible to select technology more technology is needed, it is possible to select technology more suited to the site, and develop new technology, as required, suited to the site, and develop new technology, as required, through additional examination of technological development through additional examination of technological development cases as in the Chinese case outlined this report.cases as in the Chinese case outlined this report.

Moreover, Moreover, ““locally suitable technologylocally suitable technology”” is selected according is selected according to the current situation of a region where the technology is to the current situation of a region where the technology is adopted, but a plan adaptable to changes afterwards must be adopted, but a plan adaptable to changes afterwards must be considered. considered.

In any event, previous measures for wastewater treatment In any event, previous measures for wastewater treatment were taken to solve actual problems, however, future were taken to solve actual problems, however, future ““locally locally suitable technologysuitable technology”” must ensure future sustainability. must ensure future sustainability.

Ideal Way of Technological TransferIdeal Way of Technological Transfer (3)

NeNecessary conditioncessary condition for for ““locally suitable technologylocally suitable technology””

●●CConstruction cost is lowonstruction cost is low・ Percentage for labor costs is higher.・Materials are cheep and possible to recruit locally.・There are few machine parts.

●● Maintenance Maintenance cost is lowcost is low・・Reduction of the electricity consumptionReduction of the electricity consumption..・・Reduction of the Reduction of the chemicalschemicals consumptionconsumption..

●●Skills are not needed for maintenanceSkills are not needed for maintenance・・System flow is simple.System flow is simple.・・Control system can be operated manually.Control system can be operated manually.

●●CContribute to local material circulation and a water cycleontribute to local material circulation and a water cycle・・Reuse as fertilizerReuse as fertilizer／／Effluent reuseEffluent reuse

The The basic basic patternpattern of system flowof system flow thought aboutthought about““locally suitable technologylocally suitable technology”” for small scale for small scale

domestic wastewater treatmentdomestic wastewater treatment

SedimentationSedimentation Trickling filterTrickling filter

（（GravelGravel））Contact Contact aerationaeration

Multi soil layerMulti soil layer

Soil trenchSoil trench

Constructed wetlandConstructed wetland

Primary treatment Primary treatment Simple secondary Simple secondary

treatmenttreatmentAdvanced treatment Advanced treatment using natural systemusing natural system

ReuseReuse

Sludge treatmentSludge treatment

FertilizingFertilizing（（How to dry?How to dry?））

EffluentEffluent

Consideration of sludge treatment is very importantConsideration of sludge treatment is very important

ThickeningThickening DewateringDewatering Dispose as wasteDispose as wasteTypical sludge treatment of small scale plant in JapanTypical sludge treatment of small scale plant in Japan

Reuse is not Reuse is not premisedpremised

Technology development for Technology development for fertilizingfertilizing is performed in a partis performed in a part

Mobile dryer Lime Drying ProcessLime Drying Process

Lime Drying ProcessLime Drying Process （（Tochigi pref.Tochigi pref.））

Sludge is dried by chemical reaction heat generated from mixing lime and water of sludge

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