Wastewater Sludge Recycling/Reuse

in Japan

Workshop on Urban Fecal Sludge Management

23rd February 2010, Hanoi, Vietnam

Takehiko Kawai Director

Classification of Sewage Treatment Processes in Japan As of the End of FY 2006

Recovery of Resource and Energy from Sewerage Sludge, in order to ensure stable treatment and to solve Global Warming

Recycling of Resource and Energy from Sewerage

Amount of Sewerage Sludge Production

Fiscal Year

3

15 15 16 17 20

24 24

30

38

45 48

50 52

56 60

64

67 70

74 77

78

78

0

10

20

30

40

50

60

70

80

90

0

500

1,000

1,500

2,000

2,500

88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09

Recyc

le r

atio

(%)

Am

ount

of se

wag

e s

ludg

e (th

ousa

nd

dry-

solid

ton)

Recycle ratio of Sewage Sludge

Cement

Landfill

Fertilizer

Bricks, tiles

Other

Fuel

Land fill site

Tree Chart of Sludge Resources

Publicity Tool Tree chart of sludge resources

LEGEND

Piled type composting

Horizontal shovel type Sludge compost products

Sludge Utilization: Compost

Fertilizermanagementlaw

Waste disposaland Cleaninglaw

Dioxinmanagementlaw

Managementstandard forprevention ofHeavy metalaccumulationin soil foragriculture

Law forprevention ofagriculturallandcontamination

(Note)Environmentalstandard for soilcontamination

Content Elution amount Content Content Content Elution amountAlkilmercury ND NDTotal Mercury 2 mg/kgDS 0.005mg/l 0.005mg/lCadmium 5 mg/kgDS 0.3mg/l 1mg/kg-rice 0.01mg/lLead 100mg/kgDS 0.3mg/l 0.01mg/lOrganic Phosphorus 1mg/l NDChromium (Ⅳ） 1.5mg/l 0.05mg/lChromium 500mg/kgDSArsenic 50mg/kgDS 0.3mg/l 15mg/kgDS 0.01mg/lCyanogen 1mg/l NDPCB 0.003mg/l NDCopper 125mg/kgDSZinc 120mg/lNickel 300mg/kgDSSelenium 0.3mg/l 0.01mg/lDioxin 3ng-TEQ/g 1ng-TEQ/g

Officialstandard fornormalfertilizer

Officialstandard fornormalfertilizer

for Ash, Slag,etc.

Standard forSoil itself

Only for paddyfieldStandard forsoil itself

The titles of the laws mentioned above are not the full titles.

Quality of product (3)

Heavy metals and other undesirable substances

Thickening

Digestion

Dewatering

Drying

Carbonization

Incineration Sintering

Dried and composted sludge

Supernatant

Utilization for agriculture and greenery

Incineration

ash China

Town in

Yokohama

City

Recycling of Resource and Energy from Sewage

Phosphorus

recycling system

Carbonization of Sewer Sludge

11

Gifu Prefecture

Fertilizer produced from

sewage sludge is used for

the production of vegetables

in Gifu, and the vegetables

are famous for their

excellent quality.

Kobe-city

Biogas Station

Biogas Refinery

Tokyo Solid Fuel

Electric Power Generation

Problems with Digestion Gas

Problems for utilization

① Warming facilities and gas tank are corroded by digestion Gas which

contains hydrogen

② Digestion gas which contains Siloxane creates problem by

crystallization to warming facilities and gas blower.

③ Methane concentration is approximately 60%. Consequently, heating

capacity is lower with about half of the capacity of the city gas.

Malfunctioning by Siloxane

Digestion Tank

Desulfurizer

Waste Gas Burner

LP Gas Tank

Boiler for warming Digestion Tank

Refining Digestion Gas to Bio Natural Gas

■2004 Kobe

city

Kobelco

Eco-Solutions

■2005

Kobe

City

Kobelco

Eco-

Solutions

Public Works

Research

Institute

Refining Digestion Gas to

Natural Gas (Joint Research)

Refining Digestion gas to Natural Gas and commercialization for

car fuel (joint Research)

Ｇａｓ ｒｅｆｉｎｉｎｇ ｓｙｓｔｅｍ

Kobe Bio Gas Station

Refining System of Digestion Gas (water scrubbing process flow)

Treated WW

Compressor

Sewage Sewage treatment

Treated WW

Kobe Biogas Kobe Biogas Station

Digestion tanks

Water pump

Scrubber

Treated water

Low pressure tank

Solubility-difference (CH4 and CO2)

pressure solu

bil

ity

Sludge

To treatment system

Pump

Kobe city bus

Effective use of Kobe Biogas Vehicle for officials Taxi

Truck for sludge cake

Garbage wagon

Home dispatch

Drain pipe

sweeping

machines

Project: Pouring into the City Gas

Properties Unit Digestion Gas

（Pre-Desulfurization） Kobe Bio Gas

Acceptance standard value by Osaka Gas

Methane Vol% ５９.７ ９８.２ －

Carbon dioxide Vol% ３７.０ ０.６ ≦０.５

Oxygen Vol% ０.４ ０.２ ≦０.０１

Nitrogen Vol% ０.８ １.０ ≦１.０

Hydrogen Sulfide ppm ３３０ ＜０.１ ≦０.６５

Siloxane mg/Nm３ １４.５３ ０.００５以下 －

High rank calorific value MJ/Nm３ ２３.８ ３９.３ ４５.０

Smell mg/Nm３ － － １２～１６

Actual proof facility of Pouring into the city gas.

Networking of renewable biomass energy

Agriculture Green

Water

Foods

Wastewater System

Water Reclamation

Energy- Regenerating

Kobe city

Study on Economical Biomass Methane Fermentation in Small City

by Suzu City and JIWET (Japan Institute of Wastewater Engineering Technology)

The most important issue for sewage sludge treatment is the increase of treatment cost. Suzu City, which is located in a coastal area, expects to face an increase of cost for its sludge treatment. Suzu City is therefore promoting waste recycling by combining sewage sludge with other biomass and raw garbage from businesses to obtain methane fermentation. By using biogas energy to dry sewage sludge for utilization as a fertilizer, Suzu City expects to realize important cost saving for sludge treatment and other biomass treatment. The facility specifications were decided in 2005. The facility performance has been evaluated since the time it went into operation in 2007 to 2008. The purpose of this study is to evaluate the effects of such facility.

Location of Suzu City

Gas tank Machine building

Methane fermentation

Heating

building

Dryer

Control building

2/2wastwater

treatment

Sludge treatment building

消毒施設

1/2wastwater treatment

Photo.1 Biomass methane fermentation treatment plant in Suzu City.

Sludge treatment flow in Suzu City Wastewater Influent

Oxidation ditch Final sedimentation tank Discharge

Sewage sludge

Sewage sludge from

wastewater treatment

plant in rural area.

Garbage

septic tank sludge

Machine building

Night soil

Heating

Thickening facilityReceiving &mixing tank

Receiving tank

Receiving tank

Receiving hopper

Storage tank

Storage tank

Solubilization tank

Methane fermentation

tank

Gas holder

Storage tank

Dewatering

Machine

DryerDrying

Dried

sludgeFree distribution

Thickening tank

Crushing &

separation

Screen

Screen Mixing tank Boiler for

heating

Biomass ， Biogas ， Energy

Legend

Heating

Wastewater InfluentOxidation ditch Final sedimentation tank Discharge

Sewage sludge

Sewage sludge from

wastewater treatment

plant in rural area.

Garbage

septic tank sludge

Machine building

Night soil

Heating

Thickening facilityReceiving &mixing tank

Receiving tank

Receiving tank

Receiving hopper

Storage tank

Storage tank

Solubilization tank

Methane fermentation

tank

Gas holder

Storage tank

Dewatering

Machine

DryerDrying

Dried

sludgeFree distribution

Thickening tank

Crushing &

separation

Screen

Screen Mixing tank Boiler for

heating

Biomass ， Biogas ， Energy

Legend

Heating

Figure 1 Schematic diagrams of biomass methane fermentation treatment facility

The results of a pot test show no hindrance for plant growth with dried sludge. It was also confirmed that dried sludge is thoroughly useful as a fertilizer.

Drying conditions has shown and confirmed that dried sludge meets EPA standards and is totally safe for health.

Possibility of utilizing dried sludge as a fertilizer

Photo.2 Results of a pot test showing

no hindrance to plant growth by dried

sludge.

Photo.3 Dried

sludge.

Life ycle cost（LCC) and life cycle CO2（LCCO2) impacts

68,662

60,124

55,377

40,633

47,000

49,100 24

23,015

0 50,000 100,000 150,000 200,000 250,000

Individualtreatment

centralizedtreatment.

Cost during year（￥/year）

Construction costUtility cost

Driving management consignment expenseDisposal cost

149,881(77%)

194,054(100%)

2,402

5,525

17,066

12,284 2,374

1,099

5

408

0 5,000 10,000 15,000 20,000 25,000

Individualtreatment

centralizedtreatment.

CO2 exhaust （t-CO2）

Amount of construction exhaustAmount of driving exhaustAmount of update exhaustAmount of abandonment exhaust

20,187(96%)

20,975(100%)

Fig.1 Comparison of LCC

Fig.2 Comparison of LCCO2