Decentralized Domestic Wastewater Treatment in Rural Areas in China Efforts of the Japan- China Water Environment Partnership Project

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Decentralized Domestic Wastewater Treatment in Rural Areas in China Efforts of the Japan- China Water Environment Partnership Project Motoyuki MIZUOCHI*, Hideaki

1 Decentralized Domestic Wastewater Treatment in Rural Areas in China Efforts of the Japan- China Water Environment Partnership Project Motoyuki MIZUOCHI*, Hideaki KOYANAGI**, Tetsuo KUYAMA**, Hirokazu IWASAKI*** *National Institute for Environmental Studies **Institute for Global Environmental Strategies ***Ministry of the Environment, Japan

2 The big issue for the domestic wastewater in China Wastewater(100 million m3) COD(10,000 t) Year COD Industrial Domestic Wastewater Industrial Domestic The amount of domestic wastewater has accounted for a larger percentage of the total amount of wastewater than that of industrial one since The gap has been widening year by year. Promoting domestic wastewater measures has been a major issue.

3 Progress of municipal sewer er service in China Number of WWTP Year Sewered coverage (%) Heavy investments have been made in the development of sewage systems in urban areas. 1,178 WWTP have been built and operated across the country by the end of 2007 and 472 plants were built between 2006 and The sewage treatment rate to 60 percent. The development of sewage systems in urban areas will further pick up speed in the future.

4 In China Clear and present problem Rural areas, with a larger population than urban areas, are far behind urban areas in the domestic wastewater measures. In Japan Percentage of sewered population (%) %/Year Year 2.8 %/Year Average Population of less than 50,000 Percentage of sewered population in urban areas with a population of over one million have reached almost 100%, but those in local city areas with a population of less than 50,000 still remain around 65 %. In these local areas, decentralized treatment systems that have low construction, operation costs have been needed and developed.

5 Importance of domestic wastewater treatment in the agricultural area in China in view of the nitrogen flow Nitrogen flow combining crops production and consumption of Taoyuan, Hunan (2006) Inputs to agriculture Crops Agricultural production Grass (grazing) Recycle : Human Agriculture 600 7,298 Fish 693 Chemical fertilizer 34,519 5,268 Agriculture Human being 5,669 1,603 From atmosphere 3,709 4,421 Incineration Waste 10,047 Eluviation Water body 2,709 Outside 25,150 Evaporation Taoyuan, Unit : t-n/year Hunan

6 Nitrogen flow combining crops production and consumption of Taihe, Jiangxi (2006) Inputs to agriculture Agricultural production Recycle : Human Agriculture Chemical fertilizer 4,600 2,731 From atmosphere Grass (grazing) 6,887 2,510 Agriculture 2,023 1,931 Incineration 1,833 Eluviation Fish 512 Human being 999 Waste Water body 2,003 Outside 7,595 Evaporation Unit Taihe, : t-n/year Jiangxi

7 Outline of Taoyuan and Taihe Taoyuan Taihe Area (ha) 444, ,700 Cultivated land area (ha) 212, ,697 Population 973, ,655 Per capita GDP (Yuan) 7,322 7,197 Electricity used for Agriculture (kw/ha) Production efficiency (%) Recycle rate (Agriculture Human)(%) Self-sufficiency of food (%)

8 The relationship between a kind of toilet using at home and satisfactory degree for its in Taoyuan and Taihe Percentage Bucket Vault Pit toilet latrine Flush toilet Type of toilet Others Taihe Taoyuan Percentage Satisfied Relatively satisfied Neither Relatively unsatisfied Unsatisfied Others Taihe Taoyuan

9 Rural Area Decentralized Wastewater Treatment Model Project (1) Study the reduction of water pollutants and what water environment management should be (2) Introduce decentralized domestic wastewater treatment technologies (3) Help those involved in the Chinese government with capacity building and enhance policy dialogue (4) International seminar on theory and practice on total pollutant amount control in Japan and China

10 Model Installation Areas (2008) Zhong and Wanzhou, Chongqing Taizhou, Jiangsu

11 Installation of Model Decentralized Wastewater Treatment Facilities Overview of Model Installation Areas Taizhou, Jiangsu New agricultural village construction has promoted the readjustment of land for industrial use, agricultural land, and residential land, and residences, which had been scattered over agricultural land before, have now formed villages of hundred to several hundred families. These villages basically use flush toilets, but conventional treatment facilities, which were based on septic tanks installed in individual households, do not provide satisfactory treatment of wastewater. Economic growth has increased the convenience of the land to make it difficult to acquire a large land lot for a wastewater treatment plant, which makes it inevitable that wastewater plants will be installed near residences.

12 Taizhou Jiangsu

13 Installation of Model Decentralized Wastewater Treatment Facilities Overview of Model Installation Areas Zhong and Wanzhou, Chongqing Comprised of purely agricultural, mountain villages with large, terraced paddy fields. Located in the upper reach of the Three Gorges Dam, villages of several thousand people are scattered, and wastewater treatment must be provided for each of these villages. Since the incomes of those in the purely agricultural villages are not so high, construction, maintenance, and operation cost requirements for wastewater treatment plants in these areas are severe. Relatively large land lot can be secured for a wastewater treatment plant, though it is difficult to secure a flat land lot in the hilly areas.

14 Wanzhou Chongqing Zhong

15 Selection of Treatment Systems: Taizhou Effluent water quality standards for Taizhou CODcr BOD SS NH4-N Fecal coli. 60 mg/l 20 mg/l 20 mg/l 15 mg/l 10 4 MPN/L The difficulty of acquiring large land lots, and the proximity of treatment plants to residences requires measures against odor to be taken. Construction, maintenance, and operation costs as well as the production of sludge must be kept low. A gravel contact aeration system was selected. Increasingly used as a decentralized treatment facility in Japan This system is topped with soil to produce fewer odors. Less sludge production than an activated sludge process

16 Selection of Treatment Systems: Chongging Effluent water quality standards for Chongqing CODcr BOD SS NH4-N 100 mg/l 30 mg/l 30 mg/l 25 mg/l To keep treatment plant construction, maintenance, and operation costs low. Relatively large land lot can be secured for a wastewater treatment plant. Preliminary Contact Aeration Constructed Wetland System was selected. Because Japan has no experience in domestic wastewater treatment using a constructed wetland, a constructed wetland designed by China with a good track record was combined with this wetland.

Settling and sludge storage tank Contact aeration tank

17 Overview and Features of Treatment Systems Gravel Contact Aeration System Influent Screen Grit chamber Settling and sludge storage tank Contact aeration tank Contact filtration tank Settling tank Disinfection tank Effluent

18 The situation of the construction planned site: 150m3

19 A plan for treatment facility of 150m 3 capacity Ground plan Cross section

20 Condition for construction of same size facility in Japan Treatment capacity : 100m 3 /day

21 The situation of the construction planned site of 40m 3 and a plan

22 Condition for construction of same size (40m 3 ) facility in Japan

23 Overview and Features of Treatment Systems Preliminary Contact Aeration Constructed Wetland System Influent Screen A existing facility using same system in Chonggimg (1,000m 3 /day) Settling and sludge storage tank Contact aeration tank Settling tank Constructed wetland Effluent

24 The state of the town and discharged domestic wastewater Zhong Wanzhou

25 A plan for treatment facility using the constructed wetland Treatment capacity : m 3 /day

26 Future Prospects and Issues Treatment or disposal of sludge must be further studied with an eye toward the future. Basically, produced sludge should be recycled as fertilizer for use in these rural areas, and how it should be recycled must be studied also from the perspective of farmers. Especially, whether to recycle sludge as liquid fertilizer or dry fertilizer, which decides whether to add a sludge drying process or influences the design of a treatment system in other ways, must be clarified in view of the form of agriculture in that region. Since these decentralized domestic wastewater treatment systems are also important in other countries, further efforts must be made to develop the Japan-China water environment partnership project into foreign aid based on cooperation between the both countries.

27 Thank you for your attention

International Conference Thai Water 2013: Water for the Future Decentralized Domestic Wastewater Treatment in Asia

International Conference Thai Water 2013: Water for the Future Decentralized Domestic Wastewater Treatment in Asia Decentralized Domestic Wastewater Treatment in Asia Tetsuo Kuyama Manager (Water Resource Management) Natural Resource and Ecosystem Services Area Institute for Global Environment Strategies (IGES) Sanitary