Energy-saving (or net energy balanced) decentralized water recycling technology

ENTRY DATE: 19.11.2013 | LAST UPDATE: 19.11.2013

CATEGORIES:

  • Water Resources
  • Reclaimed water use

TECHNOLOGIES MATURITY:

Currently at the research stage

Technology Owners:

  • Kazuo Yamamoto (Professor, Environmental Science Center, The University of Tokyo)
  • Tohoku University, Ritsumeikan University, Waseda University, Yamagata University

Needs Address

The need to compensate for a shortage of water arising from changes in rainfall patterns due to climate change. 

Adaptation effects

Securing water resources to deal with drought resulting from climate change

Overview and Features

  • With continued industrialization, urbanization and motorization in Thailand, the country is dealing with challenges such as reducing the vulnerability of water resources, securing clean and safe water, and protecting water quality.
  • To resolve these challenges, it will be important to implement policies and measures that promote the rational use of water and the reuse of water. Successfully purifying untreated wastewater and eliminating pollution will increase the quantity of water resources that can be used in daily life and enable sound water management. Because it was recognized that research is needed in this area, it was decided to conduct the "Research and Development for Water Reuse Technology in Tropical Regions" project.  
  • As a new technology for energy-saving, decentralized water reclamation, the aim was to introduce a system that incorporates anaerobic digestion for wastewater from commercial buildings and food waste. 
  • More specifically, bench-scale testing was conducted using an anoxic biofilm fixed-membrane separation activated sludge process and an inclined-plain membrane bioreactor oxidation ditch. Bench-scale experiments are to clarify the optimal operating conditions of a system, from which biogas is obtained, by combining semi-dry and wet anaerobic digestion, and use a process mixing food waste with sludge from waste treatment. Based on the findings, a pilot-scale test of the same system will be conducted, and performance evaluated. 

Figure: Overview of Technology Development in WateR-InTro project

Cost

For reference: Budget of the Science and Technology Research Partnership for Sustainable Development (SATREPS) program

  • Average approx. 36 million yen per topic (for 3 – 5 years)
    Source: Website of Japan Science and Technology Agency http://www.jst.go.jp/global/koubo.html
  • Chulalongkorn University (partner research institute in Thailand) covers one-third to one-fifth of the demonstration unit's installation cost of a johkasou from Japan.

Energy source

Equipment uses electricity and biomass (food residue from cafeteria). 

Ease of maintenance

  • Stability of water quality is very high compared to typical small-scale treatment processes. Safety for uses such as watering is high. The system provides stable production of highly value-added water. 
  • As maintenance can be focused on maintaining water permeability, it can easily be automated. 

Technology performance

  • The technology can make use of food residue biomass, so can reduce energy consumption by about 40%. 
  • With further technical improvements (making itMBR more energy-efficient), the system can become energy self-sufficient if the supply of biomass increases. 

Considerations

  • A framework is needed to ensure revenues come from sewerage fees, and a system must be designed to incentivize water recycling, such as gradually increasing charges. 
  • Local companies are needed to offer a business service of patrolling maintenance, with scheduled or remote monitoring. 

Co-benefit, suitability for developing countries

  • The spread of energy-efficient technologies that can help to mitigate increases in greenhouse gas emissions. 
  • Creation of employment for installation, operation and maintenance of the products developed. 

Information Resources

Science and Technology Research Partnership for Sustainable Development (SATREPS)

  • http://www.jst.go.jp/global/kadai/h2005_thailand.html
  • http://www.jst.go.jp/global/kadai/pdf/h2005_h23.pdf

SATREPS research theme: Research and Development for Water Reuse Technology in Tropical Regions

  • http://www.envrisk.t.u-tokyo.ac.jp/waterintro/j_index.html

Japan Science and Technology Agency (JST)

  • http://www.jst.go.jp/pr/jst-news/2009/2009-12/page09.html