Wastewater Sludge Recycling/Reusein 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

Recycling of Resource and Energy from Sewerage
Recovery of Resource and Energy from Sewerage Sludge, in order to ensurestable treatment and to solve Global Warming

Amount of Sewerage Sludge Production
2,500

90
Fuel

2,000

67
OtherFertilizer

45

1,000

78
77

50

52

56

500
15 15 16 172070
60
50

Bricks, tiles

3830

80

78

64
Cement
60

1,500
48

70

74

40

30
LandfillRecycle ratio (%)

Amount of sewage sludge (thousand dry-solidton)

Recycle ratioof Sewage Sludge

2024 24

100088 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09

Fiscal Year3

Land fill site

Tree Chart of Sludge ResourcesTree chart of sludge resources
LEGEND

Publicity Tool

Sludge Utilization: Compost
Piled type composting

Horizontal shovel type

Sludge compost products

Quality of product (3)Heavy metals and other undesirable substances
Management
standard for Law for(Note)
Fertilizer
Waste disposal Dioxin
prevention of prevention ofEnvironmental
management and Cleaning management Heavy metal agricultural
standard for soil
law
law
law
accumulation land
contamination
in soil forcontamination
agriculture
Content
Elution amount Content
Content
Content
Elution amount
Alkilmercury
ND
ND
Total Mercury
2 mg/kgDS
0.005mg/l
0.005mg/l
Cadmium
5 mg/kgDS
0.3mg/l
1mg/kg-rice
0.01mg/l
Lead
100mg/kgDS
0.3mg/l
0.01mg/l
Organic Phosphorus
1mg/l
ND
Chromium (Ⅳ）
1.5mg/l
0.05mg/l
Chromium
500mg/kgDS
Arsenic
50mg/kgDS
0.3mg/l
15mg/kgDS
0.01mg/l
Cyanogen
1mg/l
ND
PCB
0.003mg/l
NDCopper125mg/kgDS
Zinc
120mg/lNickel300mg/kgDS
Selenium0.3mg/l
0.01mg/l
Dioxin3ng-TEQ/g
1ng-TEQ/g
Official
Official
Only for paddy
standard for standard forfor Ash, Slag, Standard for fieldnormalnormaletc.
Soil itself
Standard for
fertilizer
fertilizer
soil itself
The titles of the laws mentioned above are not the full titles.

Dried and composted sludge
Thickening
Digestion
Dewatering
Supernatant

DryingIncineration

Sintering

Carbonization

Utilization for agriculture
and greenery

ChinaTown inYokohama
City

Incineration
ashRecycling of Resource and Energy from Sewage
Gifu Prefecture
Fertilizer produced fromsewage sludge is used forthe production of vegetables
in Gifu, and the vegetables
are famous for their
excellent quality.

Phosphorus
recycling system

Kobe-city

Tokyo

Solid Fuel

Biogas Station
Carbonization ofSewer Sludge
Biogas Refinery

Electric Power Generation 11

Problems with Digestion Gas
Waste
Gas Burner

Desulfurizer

Boiler forwarming
Digestion Tank

Digestion
Tank
LP Gas Tank

Malfunctioning by Siloxane

Problems for utilization① Warming facilities and gas tank are corroded by digestion Gas whichcontains hydrogen② Digestion gas which contains Siloxane creates problem bycrystallization to warming facilities and gas blower.
③ Methane concentration is approximately 60%. Consequently, heatingcapacity is lower with about half of the capacity of the city gas.

Refining Digestion Gas to Bio Natural Gas
Refining Digestion Gas toNatural Gas (Joint Research)■2004
Kobecity■2005

Public Works
ResearchInstitute

Kobe
City

KobelcoEco-Solutions

Ｇａｓ ｒｅｆｉｎｉｎｇ ｓｙｓｔｅｍ

Refining Digestion gas to Natural Gas
and commercialization for
car fuel (joint Research)

Kobelco
EcoSolutions
Kobe Bio Gas Station

Refining System of Digestion Gas(water scrubbing process flow)Kobe Biogas Station

Kobe Biogas
TreatedWW

TreatedWW

Digestion Sludge
tanks

ScrubberTreatedwaterPump

Waterpump

Solubility-difference(CH4 and CO2)
To treatment
systemLow
pressuretankCompressor

solubility

SewageSewagetreatmentpressureEffective use of Kobe Biogas
Vehicle for officials

Taxi

Garbage wagon

Kobe city bus

Homedispatch

Truck for sludge cake

Drain pipe
sweepingmachinesProject: Pouring into the City Gas

Actual proof facility of Pouring into the city gas.

Properties

Unit

Digestion Gas（Pre-Desulfurization）

Kobe Bio Gas

Acceptance standard valueby Osaka GasMethane

Vol%５９.７

９８.２－

Carbon dioxideVol%３７.００.６≦０.５OxygenVol%０.４０.２≦０.０１

NitrogenVol%

０.８１.０≦１.０Hydrogen Sulfideppm

３３０＜０.１≦０.６５Siloxane

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

Networking of renewable biomass energy
Green

Agriculture

Foods
Water

Wastewater
SystemWater
Reclamation
Kobe city

EnergyRegenerating

Study on Economical Biomass Methane
Fermentation in Small Cityby Suzu City and JIWET (Japan Institute of Wastewater Engineering Technology)

The most important issue for sewage sludge treatment is theincrease of treatment cost. Suzu City, which is located in a coastalarea, 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 torealize important cost saving for sludge treatment and otherbiomass 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 toevaluate the effects of such facility.

Location of Suzu City
Methane fermentation

Control building

Dryer
Sludge treatment building

1/2wastwater treatment

Heatingbuilding
2/2wastwater
treatment

Gas tank

消毒施設

Machine building

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

Sludge treatment flow in Suzu City
Wastewater Influent

Oxidation ditch

Final sedimentation tank

Sewage sludge

DischargeThickening tank

Machine building
Sewage sludge fromwastewater treatment
plant in rural area.

Receiving &mixing tankThickening facility

septic tank sludge

Receiving tank

ScreenStorage tankNight soil

Receiving tank

ScreenStorage tank

Mixing tank

Garbage

Receiving hopper

Crushing &separation

Solubilization tankHeating
Storage tank

Biomass ，LegendBiogas ，EnergyMethanefermentationtank

Gas holder
Heating

Dewatering
Machine

Dryer
Driedsludge

Figure 1 Schematic diagrams of biomass methane fermentation treatment facility

Boiler forheatingDrying

Free distribution

Possibility of utilizing dried sludge
as a fertilizer The results of a pot test show no hindrance for plant growth withdried sludge. It was also confirmed that dried sludge isthoroughly useful as a fertilizer.
 Drying conditions has shown and confirmed that dried sludge
meets EPA standards and is totally safe for health.

Photo.2 Results of a pot test showing
no hindrance to plant growth by driedsludge.

Photo.3 Driedsludge.

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

60,124

Individualtreatment

Construction cost
Utility cost
Driving management consignment expense
Disposal cost
1 4 9 ,8 8 1
40,633
49,10024(77%)

68,662

55,3771 9 4 ,0 5 4(100%)

47,00023,015050,000100,000
150,000
200,000
Cost during year（￥/year）

250,000

Fig.1 Comparison of LCC
Amount of construction exhaust
Amount of driving exhaust
Amount of update exhaust
Amount of abandonment exhaust
centralizedtreatment.

Individualtreatment

5,525

12,284

2,402

17,0662,374 5408
1,099

0

5,000

10,00015,00020,000CO 2 exhaust （t-CO2）

Fig.2 Comparison of LCCO2

2 0 ,1 8 7(96%)

2 0 ,9 7 5(100%)
25,000