●Research Trends and Results

Initiatives by the Wastewater and Sludge ManagementDivision to respond to global warming
OGOSHI Masashi, Head
OGAWA Fumiaki, Senior Researcher
FUJII Tsuyako, Researcher
MIYAMOTO Ayako, Researcher
NISHIMURA Shunsuke, Researcher
TSUSHIMA Ikuo, Researcher
IGUCHI Hitoshi, Guest Researcher
Water Quality Control Department, Wastewater and Sludge Management Division(Key words) Biomass energy, carbon dioxide, resources recycling
1. Controlling the production of greenhouse gas
from treatment processes
The Wastewater and Sludge Management Division
has striven to prevent the production of greenhouse gas(GHG) by performing statistical surveys to estimate thequantity of GHG produced at sewage treatment plants,
surveys to clarify the state of and the restriction of theproduction of methane (below “CH4”) and nitrous oxide(below “N2O”) in sewage treatment processes etc., andsurveys of the quantity of carbon dioxide gas produced
through the consumption of resources and energy for
wastewater treatment and reuse. From the results, theGHG production rate is generally clarified andcountermeasures are almost fully established, excludingthat for N2O produced by biological treatment.
Regarding another source of GHG from seweragesystems, it has been pointed out that CH4 released in
sewer pipes and N2O emission in receiving waters areimportant.

3. Studying the warming adaptation strategies
based on water reuse
As global warming advances, floods and droughts
will occur more often, lowering usable water resources,
and it is presumed that urbanization will advancewarming trends, harming urban environments.
Reusing water is presumed to be an effective way toadapt to such phenomena. The Division has been
studying the evaluation of the environmental load andof the economics of a variety of adaptive strategies
implemented using recycled water, and ways toincrease the safety of recycled water to lower thehealth risk of its use. In the future, the Division willcontinue these endeavors to aim to propose a methodof comprehensively evaluating reuse as an adaptivestrategy.
Insert 生ゴミ等投入
raw garbage
Agitation
machine攪拌装置Sewage
sludge下水汚泥

Gas refinery

ガス精製施設
都市ガス
供給

City gas supply

下水バイオ
Biogasガス

Sewage下水

2. Restricting production through the use of sewage
resources
Various technology developments are advancing
energy recovery from the heat and biomass resourcesin sewerage systems, and their spread as GHG
reducing technology should be encouraged. So theSewerage and Wastewater Management Departmentof the Ministry of Land, Infrastructure, Transport andTourism started the Breakthrough by Dynamic
Approach in Sewage High-technology Project in 2011,and Wastewater and Sludge Management Division is
now proving multiple systems under a contract fromthe above department (see the example in the Fig.).
This project will be continued with a call for thesubmission of new challenges in 2012. In addition tosuch demonstration studies, the Division is conductingresearch to enact a guideline to evaluating thefeasibility of introducing technologies to sewage
treatment plants considering the characteristics ofregions, in order to promote the wide introduction ofthese technologies. And in cooperation with the Urban

Facilities Division of the Urban Planning Department,
the Division has evaluated energy saving partnershipamong public sectors in cities such as sewerage works,
and the improvement of block level energy supply
system, and has studied the impacts of regulatory andincentive policies based on city plans and of adomestic emission trading system.

High高温消化槽temperature digester

SewageSewage heat recovery
下水熱回収加温装置
and heater

Figure Example of a Project to Verify Reformed Sewage
System Technology