Research Trends and Results

Promotion of Climate Change Countermeasures usingSewerage
YAMASHITA Hiromasa , Head; TAJIMA Atsushi , Senior Researcher; SHIGEMURA
Hiroyuki , Senior Researcher; MICHINAKA Atsuko (Dr. Env.), Researcher; OGOSHI
Masashi , Researcher; ONISHI Shohei , Researcher; KAMATANI Satoshi , Guest ResearchEngineer
Wastewater and Sludge Management Division, Water Quality Control Department
Keywords: climate change, biomass energy, dinitrogen oxide, resource circulation
1. Introduction
To promote climate change countermeasures, theWater Quality Control Department is proceeding withstudies on the dissemination and promotion of technology
for reducing GHG emissions by controlling thegeneration of dinitrogen oxide ("N2O"), one of thegreenhouse gases ("GHG") emitted from water treatment
processes and utilizing the biomass resources and energy
available from sewage.

Standard method

Nitrogen removal rate (%)

2. Control of GHG emissions from water
treatment processes
As for the N2O generated by bio-reaction, since there arestill many unclear factors including its development
mechanism, sufficient measures are not taken to control thegeneration of N2O from water treatment processes. Thisdivision, therefore, conducted a survey to grasp the status
of N2O generation at actual sewage treatment facilities, andfound that the N2O conversion rate was low and thatgeneration was controlled at treatment facilities with a highnitrogen removal rate, particularly by MBR method(Figure Fig. 1). As the result of microorganism
community analysis conducted to examine thedevelopment mechanismdeveloping factors, it was foundthat the MBR method successfully keeping kept high theabundance
ratiopercentage
ofslow-growing
nitrite-oxidizing bacteria high since nitrite-oxidizing
bacteria are retained for a relatively held long period oftime and the design allows for longer A-SRT (time during
which active sludge is under aerobic conditions), which
resulted in sufficient nitrification and control of N2Ogeneration. Therefore, the possibility was suggested 新that技術
even a treatment facility that has not adopted the MBRを導
method can control N2O generation with an appropriate
入しoperating method, such as longer A-SRT. Since なtheいsurvey so far shows a sudden increase in N2O generation in
the treatment facilities where no Yesnitrogen is removed,
measures for such phenomena should be sufficientlyconsidered.

introduction of energy recovery technology is required inlight of the potential of the country’s sewage treatment
facilities.
This division, therefore, formulated guidelines forconsidering the introduction of recycling / energy
recovery technology for sewerage (Fig. 2), andcalculation tools for estimating the effect of introduction
into target treatment facilities, in order to support thedissemination of technologies that effectively use sewage
sludge. These materials are expected to promote thedissemination of technologies that reduce GHG
emissions in sewerage projects.
AO method
Processing methodwith nitrogen
removal (exceptMBR method)
MBR method
AMX method

N2O conversion rate (%)

Figure 1: Relationship between Nitrogen
Removal Rate and N2O Conversion Rate byTreatment Method
課
題
IssuesNo
技術面での可能性確認
Checktechnical feasibility

Assumetechnology
to be
導
入 技
術 の 想定introduced

NoNo

経 economic
済 性 検証
Verifyefficiency

Determinewhether detailed
詳細検討実施の判断
study is required

事業スキームの想定
Assumeproject schemeNo

3. Climatechangecountermeasures byYeseffective use of sewage sludge
In recent years, treatment facilities that introduce
recycling / energy recovery technology (biogas powergeneration, solid fuel forming, etc.) using sewage
resources have been increasing, mainly in large cities.
However, since the rate of energy recovery from sewage
sludge as of the end of fiscal 2010 is about 13%, further

必要な手続きの確認
Checknecessary procedures

Table手引きof Contents
Chapter
2: Evaluation of technology introduction
2 章：技術導入の評価
2.1 Project objective and outline of introduction
2.1 事業目標と導入技術の概要
technology
2.2
循環利用技術の導入効果2.2 Effectof cyclic-use technology introduction
2.3
事業ポテンシャルの確認
2.3 Verificationof project potential
2.4 Example
of potential user evaluation method
2.4
潜在的ユーザの評価方法例
2.5 Possibilityof project collaboration
2.5
事業連携の可能性
2.6 Evaluationof technical feasibility
2.6
技術面での可能性評価
2.7 Reference
2.7
参考図書books
Chapter 3: Project feasibility evaluation
3.1 Project cost estimation method
3 章：事業の実施可能性の評価
3.2 Economic evaluation of technology
3.1
概算事業費の算定方法
3.3 Environmentalassessment
3.2
導入技術の経済生評価
3.4 Determinationof whether detailed study is
3.3 環境評価
required
3.4 詳細検討実施の判断
Chapter 4: Examination for launching project andnecessary procedures
4.1 Examination procedure and schedule
Concept of project scheme
４章4.2：事業化に向けた検討手順と必要な手続き
4.3 Procedures in local government
4.1 検討手順とスケジュール
4.4 Discussion / Coordination with the national
4.2 事業スキームの考え方
government
4.3
自治体内での手続き
4.5 Coordination
with citizens and other concerned
4.4 国との協議・調整事項
parties
4.5
市民等関係者との調整事項
4.7 Role-sharing
4.7 役割分担

Detailed
consideration
詳細検討へ

Figure 2: Guidelines for Considering theIntroduction of Recycling / Energy Recovery
Technology --- Table of Contents and Flow (Draft)