There are few cities in China that utilize reclaimed water on a large scale.

Due to uneven water resource distribution, unreasonable development, and pollution from urbanization and industrialization, China's water resource constraints are becoming increasingly prominent this year. 4 The "Action Plan for Water Pollution Control" issued by the State Council this month requires accelerating the recycling of water resources. After several years of effort, the water-scarce city of Bishan District in western Chongqing has treated some of its urban wastewater into reclaimed water, solving the problems of municipal greening and river water replenishment. However, not many cities in China utilize reclaimed water on a large scale. Journalists' investigations have found that large-scale utilization of reclaimed water still faces constraints such as unreasonable water pricing mechanisms, lagging pipeline construction, low industrialization levels, and insufficient public awareness, and urgently needs policy support and comprehensive solutions.

Chongqing Bishan: Reclaimed Water Alleviates "Urban Thirst"

Area 915 Square kilometers, population 63 Bishan District, with an area of and a population of , is located in the Chengdu-Chongqing Economic Corridor in western Chongqing. In recent years, Bishan District has vigorously built a "deep green city," with an urban green coverage rate of 48.8% ，and requires approximately 2500 tons of water daily for road cleaning and landscape greening. “Bishan District uses reclaimed water for cleaning city roads, firefighting, toilet flushing, and watering plants and trees. Because the cost is less than 1/3 of the cost of tap water, this alone saves the government 200 tens of thousands of yuan. ”Wang Jiongqi, a cadre from the Bishan District Water Resources Bureau, introduced. Reclaimed water refers to wastewater that has been treated to meet certain water quality standards and can be reused within a certain range for non-drinking purposes. Because its water quality is between clean water (upper water) and sewage (lower water), it is also called " middle water ”。

Although Chongqing is located in the hinterland of the Three Gorges Reservoir area in the upper reaches of the Yangtze River, and its water resources are generally abundant, in some areas of western Chongqing, due to their distance from major rivers, structural and engineering water shortages are quite prominent. The per capita water resources in Bishan District are only 556 cubic meters, which is 1/3 of the per capita level in Chongqing and 1/4 of the national per capita level. In recent years, as one of the “main battlefields”

for industrialization in Chongqing's urban development new areas, the rapid development of industry has further exacerbated the water shortage. 2010 In , Bishan District took the lead in implementing the urban reclaimed water reuse project 。 “Bishan District has two reclaimed water production points, with a reclaimed water pipeline network of 60 kilometers, and a daily reclaimed water production of approximately 1 ten thousand tons, 29 reclaimed water intake points covering the main roads throughout the district. In addition to the approximately 3000 tons used daily for municipal greening, the remaining approximately 7000 tons of reclaimed water are discharged into the Binan River to replenish the river and restore the ecological environment. Bishan District's daily wastewater treatment capacity is approximately 3.1 ten thousand tons, and the reclaimed water utilization rate has reached 29%。 ”said Mo Songtao, deputy general manager of Bishan District Jieyuan Drainage Company.

Not only has the urban area achieved large-scale use of reclaimed water, but Bishan District has also introduced reclaimed water into townships. Mo Songtao introduced that currently, Bishan District has 5 township wastewater treatment plants that can produce reclaimed water. These wastewater treatment plants have a 15 cubic meter reservoir. Most of the wastewater is discharged after meeting standards, while some wastewater, after disinfection and phosphorus removal, becomes reclaimed water and enters the reservoir for use in municipal and irrigation purposes in townships.

Currently, Bishan District has launched the second phase of the reclaimed water reuse project. By the end of next year, the daily wastewater treatment capacity will be expanded to 6 ten thousand tons, and the reclaimed water production will reach 3 ten thousand tons. A new reclaimed water pipeline network of 40 kilometers will be laid, and the reclaimed water utilization rate will reach 50% covering 15 towns and streets in the entire district. “The cost of treating one ton of wastewater is approximately 8 cents, and the cost of purifying one ton of wastewater into reclaimed water is also 8 cents. Next year, we plan to supply reclaimed water to industrial enterprises. ”said Mo Songtao.

Unreasonable water prices and lagging management hinder the utilization of reclaimed water in China.

Due to uneven water resource distribution, unreasonable development, and pollution from urbanization and industrialization, China faces a severe water crisis. Data shows that of the 657 cities nationwide, 300 are classified as "severely water-stressed" and "water-stressed" cities according to the UN-Habitat evaluation standards; the per capita water resources in the Beijing-Tianjin-Hebei region are only 286 cubic meters, far below the internationally recognized per capita 500 cubic meters “extremely water-stressed standard,” leading to serious over-extraction of groundwater in northern China.

The United States, Israel, and other countries began using reclaimed water in the 1950s and 1960s, commonly used in municipal cleaning, agricultural irrigation, industrial cooling, and groundwater recharge. Reclaimed water has become the “second water source” 2012 for many cities around the world. China's use of reclaimed water started later. During the Seventh Five-Year Plan period, pilot explorations of urban wastewater reuse began, The "Twelfth Five-Year Plan for the Construction of Urban Wastewater Treatment and Reuse Facilities" issued by the State Council in clearly proposed that the scale of reclaimed water during the Twelfth Five-Year Plan period would reach 3885 cubic meters per day, to 2015 the national recycled water utilization rate reached in the year 15% In the face of water scarcity and under the guidance of national policies, the areas utilizing recycled water have expanded from northern cities such as Beijing, Tianjin, Dalian, and Qingdao to central, western, and southern cities such as Chongqing, Xi'an, Hefei, and Kunming.

Jiang Wenchao, associate professor at the School of Urban Construction and Environmental Engineering, Chongqing University, introduced that currently, many cities in China have compiled urban sewage recycled water utilization plans, but except for a few cities such as Beijing that utilize recycled water on a large scale, the overall utilization rate of urban sewage recycling in China is relatively low, and there is still a large gap with the requirements of national new urbanization. “In general, there are two main constraints on the utilization of recycled water in China: one is the imperfect water price formation mechanism, and the other is the relatively low level of recycled water utilization work at the local level.”

Associate Professor Jiang Wenchao stated that recycled water uses sewage as its source, and although the quality of recycled water is lower than that of urban water supply, the requirements for safety and stability are basically the same, and its processing cost is no lower than that of tap water. Recycled water can only be sustainably and large-scale utilized if its price is competitive with tap water. Currently, the price formation mechanism that reflects the full value of water resources is still imperfect, the price of most urban domestic water is relatively low, and the public's acceptance and demand for recycled water are not high. At the same time, in terms of local work management level, true multi-departmental joint comprehensive management has not yet been achieved in terms of urban water supply, sewage treatment, recycling, and river health management.

China is also relatively lagging in the construction of recycled water supply pipelines and the management of water quality assurance. During the "Twelfth Five-Year Plan" period, the output of recycled water in China has developed rapidly, but the supporting pipeline construction has not kept pace, resulting in the waste of a considerable amount of recycled water produced in many cities. The daily production capacity of recycled water at Xi'an Qingyuan Zhongshui Co., Ltd. has reached 16 ten thousand tons, but the daily water supply is only 3.3 ten thousand tons, only 43.5 kilometers of pipeline network means that a large amount of recycled water cannot be delivered. Qingdao currently converts about 70 cubic meters of recycled water per day, but due to the lagging pipeline construction and insufficient awareness of recycled water use, except for a small amount of recycled water used by the municipal government, most of it is directly discharged into the sea. In addition, Associate Professor Jiang Wenchao also stated that compared with tap water, the water quality monitoring system for recycled water has not yet been established, and coupled with insufficient publicity, the public also has concerns about the water quality of recycled water.

Improve the unified planning of water prices

Recycled water needs more support

Urban sewage recycling can not only alleviate the contradiction between water supply and demand, but also has important significance for preventing and controlling water pollution and environmental protection and emission reduction. This year 4 month, the "Action Plan for Water Pollution Prevention and Control" issued by the State Council made specific provisions on the utilization of recycled water, requiring “By 2020 year, the recycled water utilization rate in water-scarce cities will reach 20% or more, and the Beijing-Tianjin-Hebei region will reach 30% or more .” Experts and industry insiders interviewed said that the Water Ten Measures will accelerate the pace of recycled water utilization in China, but to make recycled water the "second water source" for water-scarce cities in China, further policy support and comprehensive solutions to the bottlenecks restricting recycled water utilization are still needed.

Currently, the recycled water facilities and pipelines in most cities are mainly led by the government, and the large-scale infrastructure investment also makes it difficult for some local governments to bear. Mo Songtao, deputy general manager of Bishan District Jieyuan Drainage Company, introduced that the cumulative investment in recycled water plants and pipeline construction in Bishan may reach hundreds of millions of yuan.

Secondly, the water price formation mechanism should be improved to incentivize the utilization of recycled water. Associate Professor Jiang Wenchao suggested that, on the one hand, the water price formation mechanism should be improved to accelerate the establishment of a tiered water price system, truly reflecting the scarcity of water resources and the resource and environmental attributes of recycled water; on the other hand, by improving the technical and management levels and providing appropriate financial and tax incentives in production, transportation, and use, the supply cost of recycled water should be effectively reduced, the recycled water utilization market should be cultivated, and the development of industrial recycled water 。

should be prioritized. Thirdly, unified planning and accelerated supporting pipeline construction are necessary. Associate Professor Jiang Wenchao stated that urban sewage recycling involves multiple departments such as municipal administration, construction, environmental protection, health, and landscaping, as well as multiple units such as sewage plants and various user terminals, in terms of treatment, pipeline construction, and use. Unified planning should be implemented to form a joint force, and recycled water pipeline construction should be included in the scope of urban infrastructure and carried out simultaneously with recycled water plant construction to prevent the separation of pipelines and facilities and the separation of production and use.

At the same time, recycled water standards should be improved, and water quality monitoring and supervision should be strengthened. When some cities in China first used recycled water, they adopted a decentralized water supply method using various small recycled water treatment facilities. Due to focusing on construction and neglecting management, problems such as insufficient recycled water supply and inability to guarantee water quality have arisen. Associate Professor Jiang Wenchao suggested that when local governments carry out large-scale utilization of urban sewage, they can formulate and improve local unified standards that are stricter than national classification standards according to specific uses and conditions, and establish a corresponding recycled water quality monitoring system to ensure that the water quality meets standards throughout the entire process from source to end.