Realization of a Society in Harmony with the Environment

zResearch Trends and Results

Water Reuse
for Global Warming Mitigation
YAMAGATA Hiroki, Researcher MIYAMOTO Ayako, ResearcherWastewater and Sludge Management Division, Water Quality Control Department(Keywords) Reuse of treated wastewater, Greenhouse gas reduction

Research Trends & Results

1. Trends in the reduction of energy consumption of water
cycle systems.
As global warming mitigation becomes an international
challenge, lowering energy consumption of water cycle systems,
which include water supply and sewer systems, has become
important. Most of the energy consumed in water supply systems
is used for water intake and conveyance, water distribution andother water transport functions. It is reported that relocating water
intake sites and purification plants upstream could cut total
emissions of carbon dioxide from water works in the Tokyo
region by approximately 60% 1).
In sewer systems on the other hand, approximately 98% oftreated wastewater is discharged into the ocean or rivers without
reuse. But treated wastewater is considered as a fresh water source
available near urban areas. It is expected that reusing treatedwastewater as “reclaimed water” for toilet flushing andenvironment water could lead to further reduction of energy
consumption in urban water cycle systems 2). The Ministry ofLand, Infrastructure, Transport and Tourism (MLIT) released theReport of the Panel on Waster Reuse in 2009 3) to encourage theuse of reclaimed water for global warming mitigation.

3. Development and Evaluation of Water Reuse
Technologies for the Establishment of a 21st century type
Water Circulation System (CREST)
To reduce energy consumption by water cycle systems, theWastewater and Sludge Management Division implements theCREST project named “Development and Evaluation of Water
Reuse Technologies for the Establishment of a 21st century type
Water Circulation System” (2009 – 2014) funded by the Japan
Science and Technology Agency (JST) collaborating with theWater Management and Dam Division andResearch
Coordinator for Environmental Affairs of NILIM, Kyoto
University, and private companies on membrane filtration.
Considering technology development on energy saving ofmembrane treatment, the project aims at developing and assessing
cascade water use systems (Figure) including the relocation ofwater supply and sewer systems, water reuse and the heatutilization of wastewater for further reduction of energy
consumption of water cycle systems inside and outside of Japan.

Cascade Water Use System
Farmland2. Assessment of the global warming mitigation effects ofwater reuse.
The Wastewater and Sludge Management Division of theNational Institute for Land and Infrastructure Management(NILIM) collaborating with the Sewerage and Wastewater
Management Department of MLIT conducts surveys and researchon reclaimed water quality management and environmental andsocio-economic assessment of water reuse systems.
Establishing reclaimed water quality standards is an importantrole of the national government in ensuring the sustainable use ofreclaimed water. In 2005, the Sewerage and Wastewater
Management Department of MLIT and the NILIM established theGuidelines for Reclaimed Wastewater Quality Criteria based on
the discussions of a committee of academic experts. Guidelines
have been enacted outside Japan in recent years, including Water
recycling criteria of the California Code of Regulations(“Title-22”), which assume multi-purpose reclaimed water uses
including agricultural irrigation, and the WHO Guidelines for theSafe Use of Wastewater, Excreta, Greywater (3rd ed.) which aims
at safe use of reclaimed water in developing countries (revised in2006) 4). Revision of the Guidelines for Reclaimed Wastewater
Quality Criteria of Japan might be needed as uses of recycledwater expand.
With regard to the assessment of water reuse systems, researchis being performed regarding LCA for water reuse systems
including wastewater reclamation facilities, reclaimed water
distribution facilities and users 5) and the evaluation of thesocio-economic benefits of water reuse 6).

Water purification
City
plant

Reservoir

OnsiterecyclingRiver

Nutrient input(fertilization)
Agricultural irrigation

Wastewater
reclamation facility(Applying innovativetechnologies including
membranes and ozone)

SewerageHeat use
Large area
recycling
Effluent

Ocean

Figure: Concept of Cascade Water Use System[Sources]
1) Cuts Carbon Dioxide by Sixty-percent: Metropolitan Water Cycyle Study Committee ofJapan Federation of Water Industries Associations: Suido Sangyo Shimbun, Jan. 4, 20102) H. Tanaka (2009): Expectations of Sewage Systems as Twenty-first Century Urban
Metabolic Systems, Shintoshi, Vol. 63, No. 9, pp. 16 – 233) Sewerage and Wastewater Management Department, Ministry of Land, Infrastructure,Transport and Tourism (2009): To Promote Use of Reclaimed Water for New Social
Significance4) Asano, T., F. Burton, H. Leverenz, R. Tsuchihashi, and G. Tchobanoglous (2007) Water
Reuse: Issues, Technologies, and Applications, McGraw-Hill, New York.
5) M. Minamiyama, M. Ogoshi, A. Miyamoto (2009): Quantitative Effect of Water Reuse asa Global Warming Control Measure, FY2008 Annual Report of Wastewater Managementand Water Quality Control, Technical Note of NILIM, No. 543
6) M. Minamiyama, H. Yamagata, D. Yamanaka (2009): Research on Restoration of Water
Cycle in Collaboration with Community-based Activities: FY2008 Annual Report ofWastewater Management and Water Quality Control, Technical Note of NILIM, No. 543