Climate change mitigation in sewerage - biomass and energy … · 2009. 5. 26. · In response to a demand for climate change mitigation, attention has turned to the use of energy

Climate change mitigation in sewerage

- biomass and energy technologies Hiromasa YAMASHITA, Kensuke SAKURAI, Toyohisa MIYAMOTO, and Seiichiro OKAMOTO Recycling Research Team, Material and Geotechnical Engineering Research Group, Public Works Research Institute

1. Introduction In response to a demand for climate change mitigation, attention has turned to the use

of energy produced using waste biomass, a source which does not compete with food production. But regardless of the vast reserves of energy in waste biomass, its use is now limited by problems such as transport and collection costs, pre-processing costs, and so on.

However, types of biomass such as biosolids from wastewater produced by urban life and grass or pruned wood produced by the maintenance of public properties along roads and rivers are not only stable in terms of both quality and quantity, they are produced mainly in and around cities and their control systems are firmly in place. They are, therefore, types of biomass considered to be extremely valuable sources of usable energy.

And many sewerage treatment plants are already equipped with facilities which use energy: methane fermenting tubs, fuel conversion facilities etc. as part of their biosolids processing systems. And if it were possible for these facilities to use biomass energy from grass or wood produced by public property maintenance, it would be possible to perform the preprocessing necessary for its use extremely efficiently, spurring its use.

2. Outline of the research Maintaining roads, rivers, parks, airports, and other infrastructures produces vast

quantities of pruned wood, driftwood, grass clippings, and so on every year, but maintenance funds are invested to process and dispose of much of this material. And large quantities of biomass are produced from local raw garbage and excreta from livestock farms. The Public Works Research Institute (PWRI) is conducting research to develop technologies to efficiently use these types of biomass. This report introduces an outline of past research by the PWRI on the efficient use of biomass produced by the above public works activities.

2.1 Provision of an inventory of biomass from public works Biomass produced by public works on roads, rivers, in parks, and at airports is, as

stated above, an extremely valuable source of usable energy, and it is assumed that its reserves are relatively large.

To use the waste plant biomass which has been produced as a resource, the production volume, locations and times of the production, and its state when produced must be

1-6, Minamihara, Tsukuba, Ibaraki, 305-8516 Japan e-mail: [email protected]

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accurately measured and numerically controlled. Surveys of the composition and of the production mass of the grass and trees necessary to construct such a biomass inventory have been performed. A past survey has obtained an estimate of the quantity of grass clippings from a single mowing of the slopes on a river or roadway as an average of between 0.2 to 0.3kg-DS/(m2• time). These analysis results have been summarized as Technical Note of PWRI. The use of plant biomass as an energy source can be studied using these data.

The PWRI plans future research to build a utilization process control system to use biomass in a most appropriate way, from both the cost perspective and energy perspective (CO2 reduction).

2.2. Development of Biomass Utilization Technologies Using Sewerage Facilities The primary way biosolids has been used to produce energy in sewage treatment plans

has been the recovery of methane by anaerobic digestion, with approximately 300 such facilities now installed throughout Japan. In recent years, technologies such as fuel conversion facilities or gasification facilities have come into practical use.

The technologies introduced below have been developed by the Public Works Research Institute as biomass utilization technologies using sewerage facilities or as technologies for the effective use of regional biomass.

(1) Mixed methane fermentation technology Woody material or dried grass is difficult to ferment while still in organic form: a problem

which had to be resolved. This was done by adopting the steam explosion method to develop methane recovery technology based on mixed fermentation with biosolids.

The steam explosion method, which is a method of instantaneously releasing pressure after steaming the material for a short period using high temperature and high pressure water steam in a pressure vessel, explodes the plant biomass, refining and modifying it and lowering its molecular weight. It has been confirmed that mixed fermentation of broad-leafed tree type steam exploded material with biosolids results in methane fermentation of good quality without acid fermentation, even at solid material mix proportion (DS base) of 1:1 or more, and that methane can be generated approximately proportionally to the mixing ratio.

Dewatering the product of fermentation of the steam explosion material and biosolids has obtained water content lower than that of biosolids, confirming its good dewatering properties. Pilot testing to achieve adaptation to an actual facility will be performed in the future.

(2) Biomass energy conversion technology (PFBI: pressurized fluidized bed incinerator) In order to maximize use of calorific value of biosolids and to use energy from

processing residue and fermentation residue of regional biomass accumulated in sewage treatment plants, the pressurized fluidized bed incinerator which is a new combustion system has been developed (joint research with Tsukishima Kikai Co. Ltd., Sanki Engineering Co. Ltd., and Advanced Industrial Science and Technology).

The basic technology which has been developed includes a pressurized fluidized bed incinerator which burns biosolids etc. under pressure of about 0.2MPa.The high

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temperature high pressure combustion gas which it produces drives a turbocharger, producing compressed air which can then be converted to usable energy.

And the emissions of N2O can be cut by high temperature combustion under pressure, which makes it an effective climate change mitigation technology.

Trial operation of a demonstration plant (approx. 5t-dewatered biosolids/day) installed at the Oshamanbe Sewage Treatment Plant in Hokkaido has confirmed that combustion of biosolids and mixed combustion with plant biomass can both be performed stably.

It has also been confirmed that this technology obtains energy conservation effects which can reduce CO2 emission reduction of about 40% if it is installed at a scale of 100t dewatered biosolids/day.

(3) Biogas utilization technology as automobile fuel Biogas can be used in the same way as natural gas. The method of use which has been

the most socially effective until now is judged to be its use as automobile fuel, and joint research (City of Kobe and Kobelco Eco-Solutions Co., Ltd.) has been carried out to study the conversion of biosolids digestion gas to bio-natural gas. The research included a study of methods of refining digestion gas and repeated automobile running trials, and a plant to supply gas for use by city busses in the City of Kobe has been recently completed, bringing this technology to the practical stage. As technology to support use, the absorption storage technology, which effectively stores large quantities of biogas, has also been developed.

(4) Biogas engine system - electric power production technology In order to promote the use of biogas produced by methane fermentation in medium

and small scale sewage treatment plant, a biogas engine system for electric power production from biogas using a low-price general purpose engine has been developed (joint research with Raito Kogyo Co., Ltd. and Inoue Masa Syouten Co., Ltd.). An engine system which operates stably (power generation efficiency of 20% or higher) at the normal biogas composition of CH4 concentration of about 55% has already been developed. At this time, a long-term proving operation trial based on biosolids digestion gas is in progress at an actual sewage treatment plant, achieving continuous operation of about 1 month.

3. Conclusion Trends in the strengthening of efforts to implement climate change mitigation

technologies include a growing interest in unused or underused waste biomass such as biosolids or plant biomass. Sewage treatment plants which have already been improved as urban facilities under these circumstances can, as centers for the use of other biomass, potentially aim to play a role as basic facilities to support a recycling society. We intend to continue our efforts to conduct supporting research and technology development to take advantages of such conditions.

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Climate change mitigation in sewerage-biomass and energy technologies

Hiromasa YAMASHITAKensuke SAKURAI, Toyohisa MIYAMOTO, and Seiichiro OKAMOTORecycling Research Team, Material and Geotechnical Engineering Research Group, Public Works Research Institute

Japan - U.S. Joint Conference On Drinking Water Quality Management and Wastewater Control

March 2-5, 2009

2

Climate change mitigation in sewerage Outline

Trends surrounding biomass useWildly fluctuating price of crude oilClimate Change mitigation (trial of emission trading)

Potential of using biomass produced by public works Development of various utilization technologies

Mixed methane fermentation, biogas utilization technologiesEnergy conversion technologies (PFBI: Pressurized Fluidized Bed Incinerator)Outlines of other technologies under development

Toward implementing the developed technologies in actual projects and policies

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3

WTIスポット価格（年平均）

0

20

40

60

80

100

120

140

160

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

Year

ドル

／バ

レル

（注）2008データは1～10月データの平均値

Trends surrounding biomass useWildly fluctuating price of crude oil

WTIスポット価格(日データ)

0

20

40

60

80

100

120

140

160

86/1/2

88/1/2

90/1/2

92/1/2

94/1/2

96/1/2

98/1/2

00/1/2

02/1/2

04/1/2

06/1/2

08/1/2

Year

ドル

／バ

レル

Source) Prepared based on Cushing, OK WTI Spot Price FOB (Dollars per Barrel) http://tonto.eia.doe.gov/dnav/pet/hist/rwtcD.htm

1990 Gulf War 2001 9/11

2003Iraq war

The price of crude oil is fluctuating more rapidly and broadly than ever before. We must carefully watch medium to long term price trends.In conjunction with climate change mitigation, we are going to strengthen policies to promote energy conservation and to use alternative energies.WTI spot price (daily data) WTI spot price (annual average)

Dol

lar/b

arre

l

Dol

lar/b

arre

l

(Note) 2008 data is average of Jan. to Oct. data

Jan.

2, 19

86

Jan.

2, 19

94

Jan.

2, 19

88

Jan.

2, 19

92

Jan.

2, 19

90

Jan.

2, 19

98

Jan.

2, 19

96

Jan.

2, 20

04

Jan.

2, 20

02

Jan.

2, 20

00

Jan.

2, 20

06Ja

n. 2,

2008

4

Trends surrounding biomass use

Soaring price of phosphorus

Source: 2008 Fertilization Year: Results of Fertilizer Price Negotiations: Attachment (JA Zen-Noh)http://www.zennoh.or.jp/ZENNOH/TOPICS/release/20/06/200627.htm

○The demand for bio-fuel on top of rising world-wide food demand, is rapidly pushingup demand for fertilizers.

○International prices of fertilizer raw materials are rising at an accelerating pace

○JA started raw materials prices surcharge on fertilizer prices in 2008

Attention is shifting to the recovery of phosphorus inbiosolids.

(Index assuming 2005 = 100)

Nitrogen, phosphoric acid, potassium carbonate, and all raw materials which are part of fertilizers are at their highest prices in history, pushing

up the price of fertilizers around the world.

2005 fertilization year 2006 fertilization year 2007 fertilization year

Tripled over previous year

Tripled over previous year

Doubled over previous year

Urea (nitrogen)Ammonium phosphate (phosphoric acid)Alum chloride (potassium carbonate)

Jan. July Jan. July Jan. July Jan. May Survey by JA Zen-Noh

JA Group : Japan Agricultural Cooperative Association

Prices of raw materials of fertilizers are rising rapidly around the world. Even in Japan, the prices of fertilizers are unavoidably rising.

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Trends surrounding biomass useStrengthening Climate change mitigation

(Source) From the web site of the Ministry of the Environment（http://www.env.go.jp/earth/ondanka/ghg/2007sokuho_gaiyo.pdf）

○To achieve the Kyoto protocol reduction commitment (6% below 1990 level),emissions must be cut by 9.3% in 2008-2012

○Priority on the use of biomass and other new energies

Emissions(100 billion tons of CO2)

1.371 million tons (+2.3% compared with previous year) (+8.7%)

(+6.3%)

1.261 billion tons

Case assuming that electric power emissions unit was 0.34kg-CO2/kWh(The electric power emissions unit under the goal achievement plan of the Kyoto Protocol was assumed to be about 0.34kg-CO2/kWh

(+0.5%)1.267

billion tons (-0.8%

compared with

previous year)

1.254 billion tons

(-0.6%)

1.186

billion tons

(-6%)

Emissions must be cut by 9.3%

Case where it is assumed to be 0.34kg-CO2/kWhMust be cut 1.1%

3.8% by forest absorption source measures1.6% by Kyoto mechanisms

Base year

(in principle, 1990)

Kyoto Protocol commitment period (2008 – 2012)

Fiscal Year

(Preliminary figures)

1.34 billion tons

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Trends surrounding biomass useStrengthening Climate change mitigation

The Global Warming Prevention Headquarters (Oct. 12, 2008) decided to begin Trial Implementation of the Integrated Domestic Market in Emissions Trading

1. Purpose of the scheme• To construct rules which effectively encourage efforts to reduceemissions and develop technologies

• Use of market mechanisms to induce technology development andemissions reductions

２．Basic framework• Each corporation voluntarily sets its emission reduction commitment, and takes emission reduction measures to achieve thecommitment.

• To achieve its commitment it can trade emission credits.

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Trends surrounding biomass useJapan’s Voluntary Emissions Trading Scheme (JVETS)

Two schemes of trial implementation(1)Each corporation voluntarily sets its emission reduction commitment

and seeks to achieve it by trading the quantity it achieves above its commitment (the emissions quota) or the credits in scheme (2).

(2) The corporation creates and trades credits which can be used in scheme (1).

Domestic credits (Based on the Kyoto Protocol Target AchievementPlan, credits created as supplementary emission reductions by medium and small corporations and through emission reduction activities applying forest biomass etc. Kyoto Credits

Supplementary reduction of emissions can be traded in money(potential for new incentives)

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Trends surrounding biomass useWildly fluctuating price of crude oilClimate change mitigation (trial of emissions trading)

Potential of using biomass produced by public worksDevelopment of various utilization technologies



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Potential of using biomass produced by public works

What is biomass produced by public works?Pruned wood, grass clippings, driftwood etc. collected along rivers and roads, in parks, at airports and at other public places

Pruned wood and grass clippings yard

(City of Yokohama)

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Potential of using biomass produced by public works

Biomass produced by public works is an extremely valuable usable resource

Its energy reserves are high• It is estimated to be almost equal to the quantity of biosolids

produced in JapanIt exists in and around cities which consume large quantities of energy.Management systems are already in place.→At this time, it is processed and disposed of during

maintenance work.

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Examples of biomass produced by management of public green belts

Potential of using biomass produced by public works Establishment of a biomass inventory

The quantity and quality of biomass produced, and available period are summarized to establish the inventory

Average quantity produced: 0.2 to 0.4kg (dry weight)/m2

Yield can be increased by improving control method

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Ti河川c

Ti河川b

九州　Ti河川a

To国道c

To国道b

四国　To国道a

Ｙ河川b

四国　Ｙ河川a

O河川b

中国　O河川a

Ｓ河川d

Ｓ河川c

Ｓ河川b

中部　Ｓ河川a

Ｔ河川g

Ｔ河川f

Ｔ河川e

Ｔ河川d

Ｔ河川c

Ｔ河川b

北海道　Ｔ河川a

発生率　（kg-DS／m2）

【Reference】Giant knotweed (Polygonum sachalinense) community: 1.34 (kg-DS/m2)

Veitch’s bamboo (Sasa veitchii (Carr.)) community: (1.11 kg-DS/m2)

A resource management system is needed in order to manage it as a biomass resource and to use it stably.

Hokkaido

Chubu

Chugoku

Shikoku

Kyushu

Shikoku

T river aT river b T river cT river d T river e T river f T river gS river aS river b S river cS river d O river aO river bY river aY river b

To Nat. highway aTo Nat. highway bTo Nat. highway c

T river aT river b T river c

Production yield: (kg-DS/m2)

12


Trends surrounding biomass useWildly fluctuating price of crude oilClimate change mitigation (trial of emission trading)




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Steam explosion treatmentThe raw material is compressed with high pressure steam, maintained for between a few tens of seconds to more than ten minutes, then instantaneously released

Products of the steam explosion treatment of grassclippings, pruned wood, driftwood, and other waste plant biomass can be used for mixed methane fermentation with biosolids.

Development of various utilization technologiesMixed methane fermentation with biosolids

Recovery of methane by mixed fermentation with waste plant biomass and biosolids (image diagram).

Pre-processing (steam explosion treatment)After pressurizing by high temperature and high

pressure water steam, it is instantaneously released and depressurized, causing explosive pulverization and reduction of molecular weight of the plant biomass.

Anaerobic digestion (methane fermentation)

It is mixed with biosolids etc. then fermentation decomposition occurs under anaerobic condition

to recover methane gas.

Energy useIt is used as fuel or

to generate electricity.

Plant biomassMowing and pulverizing

14

Transforming the state of woody chips by steam explosion treatment. Physical destruction Chemical transformation


Photo 1. Steam explosion test apparatus Photo 2. Example of steam explosion material of broad-leaved trees

The acetyl groups in the hemicellulose are separated by hydrolysis, forming large quantities of acetic acid

Reduction of molecular weight of hemicelluloses and lignin

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Figure: Increase of gas production was confrimed by continuous experiment of mixed methane fermentation

実　験　ケ　ー　ス＜下水汚泥に対する爆砕物の固形物混合比＞

1.00

1.28

1.54

2.212.41

1.82

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 0.25 0.5 0.75 1.0 1.25

累積

ガス発

生量

比（対

コントロール

比）

5.0

5.5

6.0

6.5

7.0

7.5

8.0

pH　(－

)

ｶﾞｽ発生量比 pH

The quantity of gas produced increases approximately proportionally to the quantity mixing ratio

When biosolids and steam explosion material are mixed at a ratio of 1:0.5 on a dry weight base, the gas production increases 1.54 times. C

umul

ativ

e ga

s pr

oduc

tion

com

pare

d w

ith c

ase

(1.0

)

cumulativegas production

Test cases(Solid mixing ratio of stema explosion material to biosolids)

16


By using steam explosion treatment,pruned wood, grass clippings, and other plant biomass can be mixed with biosolids and fermented in anaerobicdigestion tanks at sewage treatment plants. Steam explosion treatment can use waste heat from a biosolids incinerator. The challenge is to develop a high volume steam explosion process.

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Next-generation technology to replace the fluidized bed incinerators now the most widely used type in the sewerage treatment fieldConstruction of energy saving and generating systems while taking advantage of the benefits of a conventional fluidized bed incinerators.

Development of various utilization technologiesEnergy conversion technologies (PFBI: Pressurized Fluidized Bed Incinerator)

Figure: Basic structure and flow of the PFBI (pressurized fluidized bed incinerator)

排煙処理塔

定量フィーダ過給式流動炉白煙防止ファン

集塵機

空気予熱器

白煙防止予熱器

過給機

余剰空気

煙突

排煙処理塔

定量フィーダ過給式流動炉白煙防止ファン

集塵機

空気予熱器

白煙防止予熱器

過給機

余剰空気

煙突

Moisture content unsuited for incineration is converted to energy.

New energy

Energy saving(Conventional

fluidizing blower is unnecessary.)

Joint research by the PWRI, Tsukishima Kikai Co. Ltd., Sanki Engineering Co. Ltd., and Advanced Industrial Science and Technology

Surplus air

Air pre-heater Supercharger Smokestack

Tail gas treatment tower

pressurized fluidized bed incineratorFixed quantity feeder White smoke prevention fan

Dust collector

White smoke prevention pre-heater

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Good results are obtained by experiment of mixed combustion with plant biomass

Supplementary fuel use is cut from that consumed when incinerating biosolids only (self-sustaining combustion is possible)

Development of various utilization technologiesEnergy conversion technologies(PFBI: Pressurized Fluidized Bed Incinerator)

State of combustion during mixed combustion of biosolids and wood chips (biosolids :chips = 1:1 (DS))

Also effective as a climate change mitigation

Tem

pera

ture

Mixture of biosolids and chips inserted

Pres

sure

[MPa

]

Elapsed time [hr]

Sand layer temperature (1)

FB temperature (1)

Furnace outlet gas temperature


FB temperature (2)

Combustion air pressure


FB temperature (3)

Furnace outlet gas pressure

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Development of various utilization technologiesEnergy conversion technologies (PFBI: Pressurized Fluidized Bed Incinerator)

Case of a 100t/day capacity systemElectric power consumption reduced about 40% and fuel costs between 10 and 15%CO2 emissions cut between 40 and 45% from conventional typeN2O emissions can also be cut by high temperature incinerationInstallation space cut to about 3/4 and construction cost by about 10% below that for a conventional system

加圧流動炉

Water

燃焼空気

燃焼排ガス

Air intakeCompressed air

(Used for aeration etc.)

Outline of PFBI (pressurized fluidized bed incinerator)

New EnergyEnergy saving

(Conventional fluidizing blower is unnecessary.

Compressed fluidized bed

incinerator

Combustion exhaust gas

Combustion air Supercharger

Dewatered sludge

20

Development of various utilization technologiesStrong points of PFBI

Fluidizing blower

Inducing fan

Strong point １・Pressurized combustion improves combustion efficiency. Volume of incinerator is cut to about 1/3 of that of a conventional type.

PFBI: Pressurized Fluidized Bed Incinerator

Strong point 1

Strong point 2

Strong point 3

Strong point 2・Supercharger is powered by exhaust gas energy, producing compressed air

Surplus air

Air pre-heater Supercharger Smokestack

Fixed quantity feederPFBI: Pressurized Fluidized Bed Incinerator

Strong point 3・A conventional

fluidizing blower and inducing fan are

unnecessary, saving electric power

CO2 emissions are cut by more than

40%.Dust collectorWhite smoke Prevention fan

White smoke

prevention pre-heater

Exhaust smoke treatment tower

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Development of various utilization technologiesBiogas utilization technologies

Gas refining methods, siloxane removal, storage technologies (adsorption storage)Technology for more efficient methane fermentation

Kobe City biogas station

(Supplied as fuel for city busses etc.)

22

Development of various utilization technologiesBiogas utilization technologies

Use of biomass to fuel CNG vehiclesThe high pressure water absorption method, which can achieve a high recovery rate and high density refining of methane gas is applied.

Treated wastewater is used for refinement.

Joint research by City of Kobe, PWRI, and Kobelco Eco-Solutions Co. Ltd.

Refining method

Absorption water supply method

Rated treatment quantity

Maximum pressure during use

Absorption tower dimensions

Dehumidifying method

Type of absorption water

High pressure absorption method

Transient or cyclical mode (switching possible)

Digestion gas (not desulphurized) 80m3N/h

0.99MPa

Interior diameter: 400mm, full height: about 14m

Two-tower type PSA

Absorption agent and molecular sieve

Sand filtered water

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Stable storage of plant biomassDevelopment of technology to carbonize large quantities of grass clippings

• Dry distillation gas constituent countermeasure → study of extremely low temperature carbonization

Biogas engineDevelopment of systems which can be easily introduced to medium and small scale facilities

Others (use as material)Storage technologies for phosphorus contained in biomass incineration ash

Development of various utilization technologiesTechnologies now under development (Outline)

24


Trends surrounding biomass useWildly fluctuating price of crude oilClimate change mitigation (trial of emissions trading)


Mixed methane fermentation, biogas utilization technologiesEnergy conversion technologies (PFBI: Pressurized Fluidized Bed Incinerator) Outlines of other technologies under development


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Japan’s Voluntary Emissions Trading Scheme (JVETS)

Two schemes of trial implementation(1)Each corporation voluntarily sets its emission reduction

commitment and seeks to achieve it by trading the quantity it achieves above its commitment (the emissions quota) or the credits in (2).

(1) The corporation creates and trades credits which can be used in (1).

Domestic credits (Based on the Kyoto Protocol Target Achievement Plan, credits created as supplementary emission reductions by medium and small corporations and through emission reduction activities applying forest biomass etc. Kyoto Credits

26

Toward implementing the developed technologies in actual projects and policiesImage of the creation of domestic credits using biomass produced by public works

Integrated Domestic Market in Emissions trading

Certification/verification body Domestic emissions trading

Prepared by the Public Works Research Institute with reference to documents from the Ministry of the Environment and Forestry Agency

Public green belt managers

(Grass clippings, pruning trees, and gathering

driftwood on roads and rivers, at dams, in parks

and airports, at ports, and along railway lines)

Sewerage treatment plant managers

(Use of biosolids for methane fermentation, electric power

production, and conversion to fuel)

Corporate enterprises emitting CO2

Factories etc. converting biomass to fuel

Biomass powered electric power plants Coal powered thermal electric power plants Others

①Application forproject credits

Delivery of bio-fuelDelivery of grass

clippings etc.

Electric power companies etc.

Electric power generationSale of electric power or use on site

②Certification of credits

③Sale of credits

④Purchase price

Con

trib

utio

n to

a lo

w-c

arbo

nso

ciet

y, re

duct

ion

of m

anag

emen

t cos

ts (p

rofit

abili

ty)

Kitchen garbage etc

Support organization

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Technologies needed

Methane fermentation (mixed fermentation with biosolids) Solid fuel productionGasificationUse of heat and electric power production by direct combustionTechnology to convert more unused biomass to energy

With priority on the development and implementation of technology for the efficient use of biomass energy;

• Minimizing initial investment and maintenance costs (by using existing facilities, etc.)

• Minimizing emission of CO2 in converting biomass to energy(Evaluation based on LCCO2)

28


Technologies considered necessary

Social systems and infrastructure which can efficiently utilize biomass energy are needed.

Increasing efficiency by expansion and integration(large cities)

Efficient use of local biomass (regional biomass utilization centers)

(Regional cities, agricultural villages)

Control systems for optimized use of biomass in terms of cost and energy (CO2 reduction) are needed.

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(Example case) Recycling of resources centered on sewage treatment facilitiesIntroducing other forms of biomass at an existing sewage treatment plant to produce resources and energy (Suzu City in Ishikawa Prefecture)

Source: Document from the Ministry of Land, Infrastructure and Transport

Public sewer system

Kitchen garbage

Agricultural community Sewerage system sludge

Septic tank (Joukasou) sludge and night soil

Kitchen garbage etc. are recycled as new resources along with biosolids!

・Construction completed in July 2007・Total project cost: 1.39 billion yen (around 140 billion U.S. dollar)・Subsidized by Ministry of Land, Infrastructure and Transport, and Ministry of the Environment

・The residue produced is fermented and dried, then used as fertilizer. ・The methane gas produced is recovered as energy by boiler combustion.・The energy is used to heat the methane fermentation tank and for drying during the manufacture of the fertilizer.

Suzu City Biomass Energy Promotion Plan

Water treatment plant

Suzu City Sewerage treatment plant

Receiving facility

Sewage sludge

Methane gas

HeatingGas holder

Methane fermentation tank

Sludge drier

Sludge dewatering facility

Fert

ilize

r

Fert

ilize

r

30

Climate change mitigation in sewerage -biomass and energy technologies

Thank you all very much for your kind attention.

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Documents

Climate change mitigation in sewerage - biomass and energy … · 2009. 5. 26. · In response to a demand for climate change mitigation, attention has turned to the use of energy