Current status of reclaimed water in China: an overview

This paper presents the objectives of reclaimed water use in China and the current quantities used at the national and provincial levels. Using 2015 statistical data as an example, this paper studies the in ﬂ uences of water resources quantity, gross domestic product and policy promotion hierarchy on reclaimed water use in all provincial administrative regions in China. Reclaimed water use in Beijing and Jiangsu are presented as two representative examples. China ’ s reclaimed water experience can provide some guidance for other countries facing similar water resource situations.


INTRODUCTION
China, as the second largest economic entity in the world, is a well-known country that faces serious water scarcity and water pollution (Ma et al. ). Its per capita water resource quantity was 2039.2 m 3 in 2015, approximately a quarter of the world's average level, and therefore it has been recognized as one of the 13 lowest water-availability countries throughout the world (Bai et al. ). Furthermore, the distribution of precipitation in China is uneven, with the northern and western regions having less precipitation and the eastern and southern regions having abundant rainfall (Bulletin of Water Resources in China ). As a result, floods and droughts frequently occur in China (Bulletin of Water Resources in China ). To tackle the serious disparity between water resource supply and demand, China has taken many measures to efficiently utilize surface and ground water (Yi et al. ; Lyu et al. ). These include implementing a very stringent water management system that specifies water efficiency targets (Wang et al. ), adjusting the inner structures of primary, second and tertiary industries for water-saving objectives (Chao et al. ), and implementing the trans-basin South-to-North Water Diversion Project across the country (Zhao et al. ).
In addition to regular water resources, China strives to develop alternative water resources to combat water conflict, including reclaimed water, seawater desalination and household-level rainwater harvesting (Yi et al. ; Lyu et al. ). The desalination of seawater, although its water source is stable and plentiful, requires advanced technology, incurs high cost (including capital, operation and maintenance costs) and large energy consumption and can only be utilized in coastal regions of China (Zheng et al. ). Household-level rainwater collection can provide only limited additional water resources because of the climate characteristics in China (Gu et al. ). With the advancement of water treatment technology, more and more attention has been paid to reclaimed water in providing alternative water resources to meet the increasing water demand in China (Chang & Ma ). statistical method was to first count reclaimed water data at a country level, then gather them in a city level, and finally add up all of the data in a PAR level by virtue of political administration. In this statistic, reclaimed water is specified to refer to: (i) the water through wastewater treatment plants whose water quality satisfies 'Water Quality Standard for Reclaimed Water' (SL368-2006) at the source of the domestic wastewater (Standards for reclaimed water quality ); (ii) the water through secondary treatment in wastewater treatment plants and further treatment of water reclamation plants (different treatment technologies depending on different use objectives), whose water quality satisfies 'Water Quality Standard for Reclaimed Water' (SL368-2006) (Standards for reclaimed water quality ); and (iii) the water which is diverted into water-using enterprises from wastewater treatment plants through special water supply pipelines, and further treated by those water-using enterprises. Part of this paper is a simple presentation of these statistical data as is shown in the 'Utilization quantity and objective of reclaimed water' sec-

UTILIZATION QUANTITY AND OBJECTIVE OF RECLAIMED WATER
As is shown in Figure 1, the number and production capacity of water reclamation plants and the pipeline length of reclaimed water are increasing rapidly in China.
With these developments, reclaimed water is playing an Hainan province, where all of the wastewater was reclaimed for non-potable water reuse, the volume proportion of nonpotable reclaimed water reuse was less than 37% over all PARs of China. Especially, less than 3% of the reclaimed water was applied into the non-potable water projects in the provinces of Liaoning, Hebei, Sichuan, Shanxi, Inner In 2015, the State Council of China issued 'Water Pollution Control Action Plan', and an objective regarding reclaimed water has been set in this file (Water Pollution Control Action Plan ): by 2020, the utilization ratio of reclaimed water (which is equal to the ratio of the utilized quantity of reclaimed water to the total treated wastewater amount) will have reached above 20% in water-deficient cities, and especially above 30% in the Beijing-Tianjin-Hebei region. We attempt to use '20%' and '30%' indexes to evaluate the current status of the utilization ratio of reclaimed water in all the PARs in 2015, and this result can be found in Figure 5.
In 2015, the utilization ratio of reclaimed water exceeded 30% only in Beijing, the capital of China. Shandong, Henan and Liaoning provinces completed the '20% index', and except for them, for other PARs across China, there is a gap to strive to fill to achieve the objective by 2020.

LAWS, POLICIES AND TECHNOLOGICAL STANDARDS GOVERNING RECLAIMED WATER USE
There have been laws and policies promulgated by the State Council of China and some relevant departments to promote the development of reclaimed water issues in China. In this study, we collected these files in chronological order as follows.  fees from pollution emitters, and these fees should be used for the construction and maintenance of urban wastewater treatment facilities.
In 2009, the Ministry of Water Resources of China issued a notification 'Strengthening urban wastewater reuse to promote water resources conservation and protection'. This file noted the significant importance and urgency of urban wastewater reuse. It is suggested that urban wastewater reuse be incorporated into the integrated allocation of regional water resources. This file required an increased utilization ratio of reclaimed water in application areas of groundwater recharge, industrial need, urban non-potable use, landscape environmental use, and agricultural, forestal and pasturable use.
Urban and rural production and supply of reclaimed water should be planned as a whole by comprehensively considering the drainage system, the reclaimed water facility, distribution of the pipeline network and distribution of reclaimed water to consumers to complete the recycling utilization of regional water resources. Multi-level water administrative departments should organize and compile urban wastewater reuse plans subject to a comprehensive water resources plan and overall city plan, which should be cohesive with the land plan, environmental protection plan, city water supply plan and city drainage and wastewater treatment plan.
Regarding the pricing relationship between reclaimed water and regular city water resources, the National Development and Reform Commission and the Ministry of Housing and Urban-Rural Development of China jointly put forward Since 2002, 13 standards, specifications and guidelines regarding reclaimed water have been published to provide references for engineering design, construction and operation for reclaimed water. We have listed them in Table 1.

FACTORS INFLUENCING RECLAIMED WATER USE
We attempt to investigate the possible influences of water resources amount, GDP, and policy support on the quantity of use of reclaimed water for all PARs throughout China in 2015, respectively, as is shown in Figure 6(a)-6(c).
There is an obvious data scatter in Figure 6(a), indicating that there seems to be no correlation between the amount of water resources of every PAR and the amount of reclaimed  whereas only a small quantity of reclaimed water has been Although some water quality standards have been published to guide the utilization of reclaimed water for different purposes in China, they are inconsistent in terms of indexes included in these standards and specified thresholds even for the same index (Lyu et al. ). Some water quality indexes of concern for water consumers are not included in current standards, and some indexes, such as chloride and sulfate in industrial production, are also neglected in current water quality standards (Chang & Ma ).
There is an incomplete water pricing mechanism for reclaimed water. The price of reclaimed water could play an important role in determining the extent to which reclaimed water could be used in society (Chu et al. ).
Currently, the price of reclaimed water only reflects the economic and operating costs of reclaimed water treatment facilities, but not the demand and supply of the reclaimed water market; thus, the market does not take a fundamental allocation effect on water resources into account very well A price adjustment for reclaimed water is needed, and a rational, cost-justified price structure is necessary so that the demand for tap water and reclaimed water can be balanced. (1) time required for high-quality reclaimed water projects is long and difficulties are great, and thus these projects do not effectively relieve the serious situation regarding urban water use; (2) the delivery, conservation and management system of reclaimed water is still incomplete; (3) the present water pricing mechanism of reclaimed water and tap water is still irrational; and (4) some rivers and lakes in Beijing lack ecological base flow during the dry season. Because the water quality standards of reclaimed water are still lower than the water quality standards of river and lake water bodies, using reclaimed water to supplement ecological environmental water requirements of rivers and lakes will lead to some pollution of rivers and lakes.

Reclaimed water reuse in Jiangsu province
As opposed to Beijing, Jiangsu province is a typical province with a relatively abundant amount of water resources, however, the spatial distribution of its water resources is very 2. An administrative mechanism regarding reclaimed water was preliminarily established in Jiangsu province. Jiangsu province has preliminarily constructed an integrated administrative system of water resources covering three administrative hierarchies of province, city and country.
This system can plan allocation, conservation, protection and utilization of water resources within the province.

CONCLUDING REMARKS
China is facing serious water scarcity and water pollution, which restricts its further development. To tackle the serious disparity between water resource supply and demand, besides regular water resources, China has made many efforts to develop alternative water resources to combat water conflict, among which reclaimed water plays an important role. This paper reviewed and studied the current status of reclaimed water use in China, including the following: • Utilization quantity and objectives of reclaimed water: • Laws, policies and technological standards governing reclaimed water use were listed in chronological order.
• Taking statistical data in 2015 as an example, the influences of water resources amount, GDP and policy promotion hierarchy on reclaimed water use for all PARs throughout China were investigated: there seemed to be no correlation between water resources amount and use amount of reclaimed water, whereas GDP and policy promotion hierarchy are driving forces for reclaimed water use.
• Existing problems and some suggestions regarding the present status of reclaimed water were also summarized.

• Two representative examples, reclaimed water use in
Beijing (a typical northern water-deficient city) and Jiangsu (a typical southern province having a sufficient amount of water resources but still facing a water crisis), were presented. With the advancement of wastewater treatment technology, increasing capital investment and strong policy support, China's reclaimed water is developing fast, and reclaimed water is expected to play an important role in tackling the serious water resources crisis in China.