Conversion of sewage sludge into solid fuel project in the ... · Primary sludge Wastewater Treatment 4 Final settling tank Excess sludge Gravity thickener Thickening Dewatering Digested

6th EWA / JSWA / WEF Joint Conference

„The Resilience of the Water Sector“

15-18 May 2018, Munich, Germany

Conversion of sewage sludge into solid fuel project in the City of Osaka

– For creation of a recycling-oriented society and prevention of global warming –

Tsuyoshi Sanjo

Osaka, JAPAN

17 May 2018

1




• Background

• Three Key Points

• Overview

• Benefits

• The future plan for further utilization of

biomass energy

• Conclusions

Contents

2




Osaka pref.

City area : 222 km2

Resident population: 2.66 million JAPAN

Profile of Osaka City

Osaka Castle

Dotonbori River

Universal studios

Japan

3

Tokyo

Kyoto Sewage Treatment Plants (STPs) : 12 (●)

Hirano STP

Maishima sludge treatment plant

G20 summit Osaka 2019




Influx Reaction tank Primary

settling tank Effluent

Primary sludge

Wastewater Treatment

4

Final settling tank

Excess sludge

Gravity thickener

Thickening Dewatering

Digested sludge

(from other STPs)

Dehydrator Dewatered

sludge

Slag

Recycling (Construction

materials)

Melting furnace (2000- )

City gas

Melting

Sludge Treatment

Incineration

Ash Landfill

disposal

(waste) Kerosene

Incinerator (1982- )

New sludge-recycling facility




waste

End products

Ash Landfill disposal

New approach for sludge recycling

Treatment method

5

Incineration (800ºC)

End use

Incinerator

Construction work Melting (1200ºC) Slag Slag

Sewer pipe

Material

use

(Backfilling sand additive)

GL Melting

furnace

Dewatered

sludge

Energy

use Combustion with coal

Coal-fired

power plant

Solid fuel

Carbonizing facility

Conversion of sewage sludge into solid fuel project

http://www.city.osaka.lg.jp/port/cmsfiles/contents/0000002/2862/yumeshima-container(2012).jpg




6

1 Treatment method : Low-temperature Carbonization

・Creation of solid fuel (carbon neutral energy source)

2 End users : Coal-fired power plants

・Reduction of coal consumption ・Stable use of solid fuel (full recycling of sewage sludge) 3 Implementation scheme : PFI

・Utilization of a private sector’s strength ・Outsourcing of the project implementation to a private company




Hirano STP

Project Overview

PFI

7

Dehydrator

D & B Inc.

Outsourcing Osaka

City

Carbonizing Facility

2011 2014 3 years

Design & Build

PFI Contractor

O & M Inc. Purchase & Selling Solid Fuel Inc.

Full recycle of carbonized fuel

Operation & maintenance

Coal-fired Power Plants

20 years 2034

Full recycle of carbonized fuel

Dewatered sludge (49,500 t/year)

Carbonized fuel (8,558 t/year)




Drying (700ºC)

Coal-fired

Power Plants

Carbonization furnace

Sludge dryer

Granulator Hopper

Dewatered sludge

8

Granulating

Carbonized

fuel

Low temperature

carbonization

(250-350ºC)




Granulated dried sludge

Flue gas

250-350ºC

Carbonization furnace ・Rotary kiln

・150t (33t-DS)/day

Carbonized fuel 13.0 MJ/kg (half of coal)

Φ 5-10 X 15 mm 9

Re-combustion furnace

850ºC

Suppression of

N2O generation




10

Amount (t/year)

41,875

49,500 46,004

5,500 8,558 7,935

0

10,000

20,000

30,000

40,000

50,000

60,000

Generated ash

Produced

Carbonized fuel

Dewatered sludge

Planned value 3 year-average

(2011-2013)

2 year-average

(2015-2016)

Incinerator Carbonizing facility

12,000 MWh / year

(3,800 households)




50 400 200 1,400 2,200 2,700

7,000 7,600 4,300

11,000 500 500

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

Incinerator

Sources of GHG

Chemicals

Electricity

Auxiliary fuel (city gas)

Auxiliary fuel (kerosene)

Use as coal alternative

3 year-average (2011-2013)

11

+16,750

GHG emission (t-CO2 / year)

N2O Reduction ①

Planned value 2 year-average

(2015-2016)


+10,100 +11,000

Reduction②

-10,000 -9,000

+16,750 +100 +2,000

- 14,750 (t-CO2 / year)

(emissions from 3,090 cars

circling the globe(40,000km)

Net emission (t-CO2 / year)




PSC PFI

(発注前）

PFI

(契約後）

Blanket

order

order

Operation & Maintenance: 3 years

Design & Construction: 20 years

Traditional scheme (Separate order)

PFI

0

10

20 billion yen (\)

12

Project benefit 3: Life cycle cost reduction under PFI

- \1.52 billion

(- €11.6 million)

1 € = \ 131 (March 2018)

Planned amount

order

Total project cost

Project period (23 years)

Contract amount

\17.7 billion (€135 million)

- \1.89 billion

(- €14.4 million)

PFI




Primary sludge

13

Excess sludge

Sludge Treatment

Gravity thickener

Thickening Dewatering

Dehydrator

Carbonizing

Solid

fuel Recycling

(Coal

alternative)

Melting

slag

Recycling

(Construction

materials)

Carbonizing facility (2014- )

Melting furnace (2000- )

Digested sludge

(from other STPs)

City gas

City gas

Digestion

Digestion tank

② High temperature digestion (53ºC )

Digestion gas

Mechanical

thickener

① Separate and two-stage

thickening for excess sludge




14

・Low-temperature carbonization technique converts

sewage sludge into solid fuel as energy source.

・Utilizing carbon-neutral carbonized fuel leads to

GHG reduction.

・By using PFI, the 23-year project implementation

including full recycling of solid fuel becomes more

efficient, economical, and stable.

Conclusions




Coal-fired

power plants Community


Recycle

oriented

society

Sewage sludge

Power

Promotion to use biomass fuel

Reduction of GHG emissions

15

Building a Recycle oriented society and Preventing global warming

Carbonized

fuel




16

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Conversion of sewage sludge into solid fuel project in the ... · Primary sludge Wastewater Treatment 4 Final settling tank Excess sludge Gravity thickener Thickening Dewatering Digested