Reclaimed Water in Fukuoka City

Transcription

1 Reclaimed Water in Fukuoka City Masayuki Yoshimura (Fukuoka City Institution of Professional Engineers) 1. Introduction Fukuoka City as a geographic location is not blessed with water resources, with no large rivers in the city area. Particularly in 1978, Fukuoka City suffered a severe drought and had to restrict its water supply for 287 days. After this water crisis, the administration, citizens, and business operators joined forces in making various citywide efforts towards water conservation under our city s important policy to establish a water conservation-conscious city. As one water conservation measure, since 1980 the municipal government has conducted the Treated Wastewater Reuse Project, intended to reuse treated wastewater, one of the city's stable water resources, for flushing toilets and watering trees. Bottom of a dam during the drought Water Conservation Plans 1

2 2. Treated Wastewater Reuse Project 2.1 Regulations The long-term restriction of the water supply made citizens and the administration reaffirm the value of water and the critical water situation of the city. Learning lessons from the severe drought, Fukuoka City established Fukuoka City s Outline of Measures for Economical Water Use in Based on this outline, the municipal government, citizens, and business operators in one united body have promoted the development of water resources, the effective use of water, and water-saving measures in order to aim for a stable water supply. Furthermore, by establishing Japan s first regulation to promote water-saving, Fukuoka City Water Saving Promotion Regulation and Fukuoka City Treated Wastewater Reuse Project Regulation in 2003, the city has further promoted water conservation and has popularized the use of reclaimed water. Fukuoka City Water Saving Promotion Regulation Fukuoka City Treated Wastewater Reuse Project Regulation Date of implementation December 1, 2003 December 1, 2003 Outline of the regulation - Stipulates the obligation of the administration, citizens, and business operators related to water conservation. - The installation of a gray water system has been made mandatory - Set the reclaimed water service areas - Stipulates the technical standards - Stipulates the procedure for builders to notify their water conservation plans at the time a new building is established, etc. - Stipulates the office procedure for the use of reclaimed water - Stipulates such matters as the use, quality and charges for reclaimed water - Stipulates the suspension of water supply and non-penal fine for those delinquent in payments of charges and those who obstruct on-site inspections, etc. The Water Saving Promotion Regulation and the Treated Wastewater Reuse Project Regulation 2.2 Water Treatment Fukuoka City s Treated Wastewater Reuse Project was initiated in 1980 as the first such measure in Japan. Since then reclaimed water has been used as a stable water resource for flushing toilets and watering trees along streets and in parks. Fukuoka City has two reclamation facilities: Chubu Reclamation Facility and Tobu Reclamation Facility. Chubu Reclamation Facility Tobu Reclamation Facility 2

3 Service initiation June 1, 1980 July 7, 2003 Capacity 7,200 m 3 /day 1,600 m 3 /day Treatment process Coagulation sedimentation Ozone reaction Sand filtration Chlorination Fiber filtration Coagulation sedimentation Ozone reaction Biological filtration Chlorination Fukuoka City s reclamation facilities Chubu Reclamation Facility s water treatment flow is as follows: Wastewater Treatment Plant Reclamation Facilities PACl Ozonizer Sand Filter Ozonation Reactor Fiber Filter Hypochlorite Building Clarifier Service reservoir Sprinkling to the trees of Parks & Streets Wastewater Reclaimed Water Treated Wastewater Potable Water Flow Diagram of the Project Raw water The raw water for the reclaimed water is secondary treatment effluent from the Chubu Wastewater Treatment Center. The Chubu Wastewater Treatment Center has a capacity of 300,000 m 3 /day and adopts an aerobic-anaerobic activated sludge process. Coagulation sedimentation treatment In the Chubu Reclamation Facility, impurities are removed by adding flocculants based on polyaluminium chlorides (PACs) to the raw water. 3

4 Ozonation Water is decolorized and deodorized with ozone s strong oxidizability by a reaction of ozone with water that has been treated by coagulation/sedimentation. Sand filtration treatment Floating substances are removed by sand filtering the ozonated water. Fiber filtration Water quality is improved and stabilized through a fiber filter before supplying water. 2.3 Reclaimed Water Service Areas Fukuoka City defines the reclaimed water service areas in its Water Saving Promotion Regulation. The reclaimed water service areas are set mainly in urban areas that have many large buildings and areas for new community-building through reclamation work. In reclaimed water service areas, newly-constructed buildings that have a total floor area of at least 3,000 m 2 are required to use gray water for flushing toilets. (Outside the reclaimed water service areas the total floor area is at least 5,000 m 2.) Gray water here indicates water other than potable water. Although it is possible to use rainwater or to recycle water used in buildings other than the reclaimed water supplied by Fukuoka City, most facilities use our reclaimed water because of its cost and convenience when our reclaimed water is available. Reclaimed Water Service Area 2.4 Water charges and management To popularize the use of reclaimed water and water-saving, reclaimed water charges are set lower than potable water charges. 4

5 Customers can reduce costs by 20% to 30% by using reclaimed water. Basic charge None Commodity charge (per month) Up to 100 m yen/m m m yen/m 3 At least 301 m yen/m 3 Reclaimed water charges Reclaimed Water 305 yen/m 3 Potable water 433 yen/m 3 (for purposes other than housework) Average water charges (2011) Half of the initial cost for the Treated Wastewater Reuse Project was covered by a government subsidy, and the remaining half and its running cost are covered by the revenue from reclaimed water charges. This project has been better managed through the understanding and cooperation of citizens. 3. Conclusion Fukuoka City s Treated Wastewater Reuse Project has a history of more than 30 years. In fiscal 2011, Fukuoka City supplied reclaimed water at an average of 5,300 m 3 /day to 386 places in a total service area of 1,414 ha, which is the largest in Japan. In recent years, various countries around the world have made efforts to secure water by employing every available means. We hope Fukuoka City s Treated Wastewater Reuse Project can serve as a reference to solve water resource problems all over the world. 5