Innovative Technology and System for Sustainable Water Use

Pollution and scarcity of water resources are becoming more serious owing to the global climate change and industrialization. Meanwhile, “sustainable and adequate supplies of safe water” is essential for human well-being. To increase the sustainability of safe water supply, it would be necessary to depart from the conventional one-way water usage, a single use and then disposal to environment. A paradigm shift from quantity-based water management to quality-based water management is indeed the key to establishing the sustainable water management. In the emerging paradigm, water must be used efficiently multiple times by cascading from higher to lower quality needs. This emerging paradigm requires establishing autonomous and decentralized water-recycling systems, in which diverse water resources are created, conserved and utilized effectively. In this water recycling system, for example, non-potable water (such as industrial and recreational water) occupying the majority of total demand could be provided by high-grade reclaimed wastewater. It is essential that reclaimed wastewater and polluted natural water for domestic use be of acceptable physical, chemical and microbiological quality. The main concerns are the adverse health risks of pathogens and toxic chemical compounds that are usually present at low concentrations, particularly when preset as components of complex mixtures.
Given this background, first, tools to assess the impact of thousands of trace chemicals on human health must be developed. Second, cost-effective, energy-saving and appropriate water and wastewater treatment technologies must be further explored and implemented. The aim of this project is, therefore, to develop cutting-edge advanced water and wastewater treatment systems using membrane technology, which can be incorporated in the autonomous and decentralized water-recycling systems. In addition, a novel multi-endpoint bioassay will be developed to assess the health risks of micropollutants by applying latest biotechnologies including toxicogenomics and proteomics. Microbiological risks including pathogenic bacteria and viruses are also assessed using molecular based techniques. In the creation of cutting-edge water and wastewater treatment technologies, the advancement and effectiveness are pursued by the combination of the membrane separation and conventional water treatment processes. Finally, the feasibility and reliability of the proposed water and wastewater treatment systems are comprehensively evaluated by operating demonstration plants.
The water quality achieved by the proposed cutting-edge technologies in this project will be dramatically improved compared to the conventional water treatment systems, which make it possible to recycle and reuse the water at different levels as shown in Figure. It is important to appropriately allocate the water and wastewater treatment systems to establish efficient water-recycling systems with minimum energy and costs. The concept of this proposed autonomous and decentralized water-recycling system could be applicable, not only in Japan, but also in developing countries where infrastructures have remained to be established, because it does not require high-tech infrastructures such as systematic sewer networks. This research project will contribute to the increase in international competitive power of Japanese industries in the global market of water businesses reaching 100 trillion yen in next fifteen years.

Go to page top

Sixty-five percent of Japanese land is covered by forests. More than 40% of the forest is consists by Japanese cedar and cypress plantation. Because plantation typically concentrate in headwater watershed which are an important reservoir basin to the densely populated region in downstream, water resources in Japan primary depends on water supply from the headwaters covered by forest plantations. Despite the importance of forest management, the area of abandoned forest plantation has been increased because of declining domestic forest industry and market due to low timber prices, high labor cost, and shortage of forest operators. Due to the low light conditions, understory vegetation cover tends to be sparse in the dense, unmanaged plantations, particularly Japanese cypress forests. Under such forest, infiltration excess overland flow and resultant soil surface erosion occurs. Such overland flow and soil erosion affect runoff and water quality at the downstream counterparts. Therefore, unmanaged and devastated plantations hamper the functions of forest for regulating discharge and recharge of water resources. Increasing the frequency of drought and flashy flood due potentially to global climate change also threaten the stable water supply and flood management in watersheds.
Forest thinning is essential for maintaining forest stand conditions and hydrological processes in devastated plantation forest. Recent studies demonstrated that intensive 50-60 % thinning can increase infiltration rate and reducing the opportunities of overland flow and soil surface erosion by recovering understory vegetation. Thinning generally reduces canopy interception and evapotranspiration. Thus, net precipitation reaching ground surface after thinning increases compared to the pre-thinning condition. Such increases in effective rainfall promote greater amount of groundwater recharge after the thinning. However, no quantitative assessment has been conducted for evaluating the effects of intensive thinning (removal of stems > 50%) on runoff and sediment discharge at a watershed scale. This project specifically aims to examine the influence of intensive thinning practice on the variation of low flow (drought period) discharge. We also focused on the examining production of turbidity material associated with thinning operation and forest management from the forested watershed. We finally develop innovative technique of water resources management which can equalize water supply and improve river water quality in devastated forest plantations.
We conduct intensive field observation campaign in 5 watersheds across Japan. Three watersheds located in Aichi, Mie, and Kochi had been monitored for the last five years and continuous runoff data have been accumulated which are essential for thinning experiment. Intensive field observation is also carried out in the newly established monitoring watersheds in Tochigi and Fukuoka. Water and sediment discharges are continuously monitored before and after intensive thinning practices in all of the watersheds. The changes of runoff processes before and after the thinning are examined for each hydrological components including rainfall, throughfall, evaporation, soil moisture, groundwater, Hortonian overland flow, stream runoff. We also sampled both low and high flow water for analyzing water chemistry and stable isotopes. Soil erosion at hillslope scale and suspended sediment discharge at watershed scale are also observed. Sources of suspended sediment entering channels are determined by using fallout radionuclides as a tracer of soil particles. Because methods of thinning operation vary, we also examined the effects of methods (random removal and line removal) of thinning are compared between watersheds. We then investigate the tree species (cedar and Japanese cypress) and effect of thinning on hydrological processes. Based on these filed information, we applied rainfall-runoff model for clarifying the effects of intensive thinning practice on water and sediment discharge a under various forest management conditions.
Forest conditions due to forest management practice are spatially and temporally varied. Thus, airborne laser scanning with developed remote sensing technique is applied for estimate spatial patterns of canopy structure, relative light condition under canopy, and understory vegetation cover. These remote sensing technique and rainfall-response model are combined to simulate water and sediment discharge from watersheds. We finally integrate these hydrological models into the forest growth model which can project future change of forest stand conditions and runoff under different thinning rates. The ultimate objective of this integrated model provide us potential scenario for maximize low flow discharge in drought period and reduce turbidity material in high flow period.

Go to page top

The Millennium Development Goals of the United Nations address the necessity of increases in food production to advance the fight against hunger. Future low carbon societies are likely to require increases in energy-crop production. However, it is anticipated that those increases in agricultural productions would make the world water crisis more serious. Population increases and dietal changes in developing countries would also make the crisis more serious. Here, the crisis of water does not solely consist of the crisis of “blue” water, but also consists of the crisis of “green” water which represents the water necessary for non-irrigated agriculture and ecology.
In setting up greenhouse gas reduction targets, for example, the key was the establishment of the critical level of climate change based on the future projection. Further, pathways to avoid the critical level of climate change were proposed. Similarly, for avoiding and/or mitigating the world water crisis, the development of the future projection of world water situation and the establishment of the critical level are indispensable. Pathways to avoid the critical level should be proposed as well.
Therefore, for contributing to “water security” of the world and Japan, this project aims to develop the future projection of world water resources (availability and demand), to determine the critical level of water scarcity and sustainability, and to propose potential pathways for avoiding the critical level.
This project consists of following elements.
- Develop future projections of world water resources (availability and demand) for various scenarios on climate change, population change, social change and so on by numerical simulations.
- Evaluate the sustainability of water resources from the viewpoint of depletion of groundwater, conservation of ecology, maintenance of anthropogenic activities and so on. The future projections should depict the geographical locations where unsustainable water use is conducted. However, water stress indices conventionally used in the global-scale projections (e.g., Oki and Kanae, 2006) never told us the sustainability and/or unsustainability of water resources. 　Thus, a new index or something which replaces the conventional indices is necessary.
- Determine the critical level, and show the pathways to avoid the dangerous/critical crisis of the sustainability of water. 　Necessary technologies and policies are also investigated. Finally, we will also think about the future strategy of our country.
Reference: Oki, T. and S. Kanae, 2006. Global hydrological cycles and world water resources, Science, 313, 1068-1072.

Go to page top

In the 20th century, water has gradually been a limited and precarious resource in many urban and near urban areas, due to rapid urbanization and industrialization. As a result, massive amount of water has been abstracted from surface water at distance places and transported to water treatment plants (WTPs) for purification, and eventually supplied as urban water including drinking water. In the existing water supply system, huge energy is required for raw water transportation, advanced treatment process in WTPs to ensure that water meets the drinking water quality criteria, and water distribution from WTPs to individual users. On the other hand, after usage almost all the used water is collected and transported to wastewater treatment plants (WWTPs) for purification. Until now, used water has been treated to meet the ambient water quality criteria established for receiving waters that have abundant dilution capacity, and have been disposed into the water environment. Recently, it has been reported that trace hazardous chemicals and pathogens which are passed through conventional wastewater treatment process exist in discharged wastewater from WWTPs, and enter into the water environment which supports drinking water source and various aquatic organisms.
This one pass type water use system which has been developed through the 20th century, has come to grips with some concerns; the decrease of river water flow owing to massive intake, centralization of urban wastewater discharge into the receiving waters, high energy requirement for water supply and wastewater treatment, adverse effects on human health and aquatic organisms derived from trace chemicals and pathogens. To solve these problems of ‘20th-century type urban water use system’ and to secure future water demand, development of a new water and used water treatment systems, which will lead to the establishment of urban water circulation system, are now desired.
The most distinctive feature of our developing ‘21st-century type urban water circulation system’ is repeated use of water in urban area. Because quantity of urban wastewater is so stable and reliable that we will be able to utilize it for water circulation system. By accelerating the water reclamation and reuse, there is a possibility to reduce water intake quantity for water supply and amount of discharged from WWTPs, which will lead to the conservation of natural water resources, and decrees of adverse effects on the water environment and energy consumption. We have to consider, however, the potential risk of reclaimed water and the aplicability of water reuse.
In this project, we will develop new water treatment and wastewater reclamation systems by membrane filtration technology, ozonation and advanced oxidation process technology, and their hybridization technology. We will evaluate the performance of the our developing treatment systems in terms of different characteristics in waters including raw and treated urban wastewater as well as surface water, efficiency of treatment of trace chemicals and pathogens, the toxicity and risk of reclaimed water to organisms including human being, and energy consumption. Based on these evaluations, we will illustrate applications of the reclaimed water by our developing systems.
In situ demonstration experiment will be performed in cities of Okinawa Island in Japan and south China and so on, where innovative water treatment systems are highly expected. In these demonstrations, the above-mentioned performance of our developing systems under actual service conditions will be evaluated. In addition, we intend to characterize the water quality based on some factors in targeted water such as natural organic matter (NOM), which can affect the performance of our innovative system. By taking the above information into consideration, we will propose custom-made water reclamation systems applicable for specific areas.
It is expected that implementation of this project will contribute to the renovation of urban water circulation system. In this system, the manner of urban water use will shift from ‘one pass type water use’ to ‘cascade type water reuse’, and amount of required pristine water resource and used water loading will be reduced, and the water environment will be more safe and affluent.

Go to page top

1. Outline of Research
   In order to help solve the world’s worsening water problems, properly treating domestic wastewater and effectively using treated water on a regional scale would bring great benefits. Uses include domestic water for water shortages and measures against global warning such as usage for maintaining river flow and for water amenity facilities. We aim to develop a new water treatment system incorporating low-fouling membranes to be newly developed, and integrating multiple membrane technologies (Membrane Bioreactor　+ Reverse osmosis) and installing it within a region. This would create an environment for supplying treated water of adequate quality to meet various applications. This water treatment technology will integrate sophisticated technologies for using natural energy and information management technology to organically connect individual facilities, thus constructing a unique new system for using regional water resources, called “Integrated Intelligent Satellite System (IISS) = satellite system integrating water/energy/information.”
2. Technology Development
   (1) Fouling control of membrane
   In this research, we will develop a new low-fouling membrane by focusing on the molecular structure of water, completely different from the conventional type. We will also develop new fouling control technology using an electric field that can effectively utilize natural energy that is an unstable power source.
   (2) Establishment of self-sustaining operation support system
   Chemoinformatics technology has recently been progressing rapidly. We will develop a technique for predicting membrane fouling and construct an operation support system based on it.
   (3) Evaluation of safety of treated water
   To encourage effective use of treated water (including drinking), we will investigate a new technology for evaluating the safety of treated water using cultured cells.
3. Prospects
   This system considers speed, safety, real-world practicality, and flexibility to handle the various water problems to be solved by Japan and the world. Through the strategic creative research promotion project of Japan, we will construct the foundation for developing new water businesses and spread the IISS developed in this project worldwide.

Go to page top

The goal of the present study is to develop an innovative water management system with decentralized water reclamation and cascading material-cycle applicable to agricultural areas. The perspective of climate change mitigation and adaptation is also incorporated into the development. This project is subdivided into four research areas: 1) development of an agricultural nonpoint source pollution control technology using cover crops, 2) development of a decentralized water/bio-resource reclamation system, 3) construction of a cascading water/bio-resource recycling system, 4) integrated evaluation of the novel water management system.
The technology developed in research area 1 (G1) will simultaneously actualize the prevention of nitrate pollution of groundwater and reduction of N2O gas emissions. Moreover, l-lactate fermentation of harvested crops in non-sterile conditions and subsequent phosphorus recovery will be developed.
A decentralized water/bio-resource reclamation system “without additional water” will be developed in research area 2 (G2). The system will comprise a composting process for both human and livestock excreta, and a water reclamation process with nutrient recovery from their urine.
Prevention of nonpoint source pollution and production of valuable products from wastes in agricultural areas will simultaneously be actualized by development of a cascading water/bio-resource recycling system in research area 3 (G3).
A modeling approach will be applied in research area 4 (G4) to evaluate the innovative water management system. We will propose a novel, rural-area system utilizing the integrated water management system for simultaneously minimizing greenhouse gas emissions and water pollution.
Development of sustainable water management systems in an agricultural area is essential for guaranteeing the safety and security of both water and food. Construction of decentralized water reclamation and management systems is urgently needed in agricultural areas, because pollution sources in such areas are diffuse; different from urban areas where intensive wastewater treatment is available. Moreover, innovative cascading water/bio-resource recycling systems should be developed to effectively utilize the diffused biomass in agricultural areas and minimize the pollution loads discharged into water systems. Optimal design and evaluation of the integrated systems are important from various perspectives: preventing water pollution, adapting to and mitigating climate change, and material cycle. I hope to contribute to guaranteeing the safety and security of water and food both in Japan and world wide by bringing this innovative water management system into fruition through our research.

Go to page top

Safe and stable water supply is strongly required in highly-populated metropolitan areas in Asia. However, the current water resources are vulnerable in those cities. Climate change would accelerate localization of water resources and consequently it would become more difficult to keep stable water resource. To assure the safe and stable urban water supply under such circumstances, we must discuss the availability of “rainwater”, “groundwater”, and “reclaimed water” as well as surface water including river and reservoir. Such “ubiquitous water resources”, which are the precious water resources lying in cities, are very important to solve water use issues in urban area. Yet, limited information is available in regard to their quantity/quality and how to utilize them to establish well-balanced urban water use systems under climate change conditions.

This project aims to reexamine the current urban water use system and propose a new one adaptive to the future climate change. In the new system, each water resource is properly allocated to each water use by considering the balance between water supply and demand. This requires information on available amount and detailed quality of various water resources. Two river watersheds; Ara river, Japan and Hon river, Vietnam, are selected as research fields. They are located both in Asian monsoon area but are on different phases in economic and demographic growths. We are pursuing urban water use strategies suitable for each watershed from various angles.

The distinctive feature of our project is its comprehensive and multiphasic approach to evaluate the urban water use systems. It consists of five different research groups such as 1) Watershed Water Resources group, 2) Urban Rainwater Management and Use group, 3) Urban Groundwater Management and Use group, 4) Water Quality Assessment group, and 5) Urban Water Use Design group.

1) Watershed Water Resources group conducts advanced hydrological simulations in watersheds to evaluate the influences of climate change on the availability (quantity and quality) of surface water and lake water.
2) Urban Rainwater Management and Use group collects information on amount and quality of rainwater and runoff water and then discuss possible strategies of rainwater harvesting and groundwater recharge by promoted infiltration.
3) Urban Groundwater Management and Use group investigates the current status of groundwater quality and recharge mechanism. Additionally, this group develops an innovative treatment technology including arsenic removal to provide safe water.
4) Water Quality Assessment group develops and proposes a comprehensive method and a novel index to evaluate quality risk of surface water, rainwater, groundwater, and reclaimed water. The method is for “comprehensive risk of health-related microorganisms” in which infectivity or viability of pathogenic microorganisms including virus is incorporated in risk evaluation. The index is named as “water quality transformation potential” in which biological stability of water during storage and distribution is examined. These two indices are useful for allocation of water resources for each water use.
5) Urban Water Use Design group devises a totally systematic method for designing water use by evaluating environmental cost and user preferences. Through the designing process, information and knowledge on the various water resources are shown to water users utilizing the outcomes of above four groups.

Finally, we aim to develop “well-balanced urban water use systems” by integrating all achievements of the five research groups.

Go to page top