Comprehensive Evaluation of Effectively Utilizing Reclaimed Water to
Accomplish Sustainable Development in Tianjin, China
Graduate School of Life and Environmental Sciences, University of Tsukuba
Nan XIANG
Graduate School of Life and Environmental Sciences, University of TsukubaFeng XU
Graduate School of Life and Environmental Sciences, University of Tsukuba Yoshiro HIGANO

1.

Introduction

Water resources are one of the most important things for human existence and social development. Also, with theincrease of economic and population in developing countries, water scarcity and pollution problems are becoming
more and more prominent recently. Wastewater reuse has drawn increasing attention worldwide as an integral part ofwater resources management. Such a move is driven by two major forces: scarcity of clean water resources andheightened environmental concerns [1-3]. Reclaimed water reuse has been used in large municipalities in many partsof the world, especially in areas where the water resources are scare and population and economic growth is rapid[4]. Tianjin is one of the typical areas in point. In 2009, only 2.01% of total water supply in Tianjin comes fromreclaimed water reuse, the reclaimed water projects have just started.
Reclaimed water reuse practice can be traced back to several centuries ago. And there are a large number ofstudies on waste water treatment from technological and engineering aspects. However, there is rather rare researchon reclaimed water utilization modeling and prediction. In most of these studies, conclusions are derived from simple
data analysis and foreign experiences [5-8]. Research on construction and analysis of a comprehensive simulation
policy that includes the introduction of current treatment technologies to control water pollutant emissions without
deteriorating the socio-economic activities level are badly needed.
In the study, we selected Tianjin city as an objective region, and utilized linear modeling as research method,
constructed comprehensive evaluation model to prove the feasibility and possibility on using reclaimed waterpromotion and water quality control policy to improve economic and social development.

2.

Current situation of the catchment area

Tianjin, one of four biggest municipalities in China, is located in northern China, near Beijing, capital of China,
and the downstream of Haihe River basin.

2-1

Local situation

There are 13 districts and 3 counties in Tianjin, the land area is 1,191,970 hectares. About the land usage,
agriculture land accounts for the biggest part, 60.87%; construction land accounts for 32.13%; and unused land is829.85ha, accounts for 7%. The total population in Tianjin in 2009 is 122.816 million, and with the urbanization
process, the urban population increasing rate is much higher than rural population.
From the following figures, we can see that Tianjin’s GDP keeps a steady increasing trend; the increase rate isabove 10% per year. Also, the three industries composition demonstrates that Secondary Industry is the monopoly
industry while its composition steady rises; primary industry only contributes a little to Tianjin’s economic, and its
composition is low; tertiary industry’s GDP contribution declines year by year[9].
2-2 Water supply situation
Water shortage is a serious problem in Tianjin. Total water resource amount in 2009 is 2337 million m3. The percapita water resources in Tianjin is 190 m3 in 2009, it is only 1/13 of China average, and only 1/52 of world average.
And the water supply structure is not stable for future development. Water supply is largely depending on
surface water which is highly pullulated. And over 25% of water supply comes from water transferred from the otherarea, such as Luan River in Hebei province. Reclaimed water only contributes to 0.51% of total water supply. Largetransferred water supply dependence is not only leading to resource waste, but also causing water supply unstable[10]. Reclaimed water can be a potential supply resource in saving water shortage problems.

8000

20

6000

15

4000

10

2000

5

0

0

Fig.1 Location of Tianjin City, China

2-3

GDP(Billion
Yuan)
GDP increaserate(%)

Fig.2 GDP trend in Tianjin

Water quality situation

Surface water quality in Tianjin is not enlightened; over 70% of surface water in Tianjin is in inferior V level.
Also, from figure 4, rivers with red line are over qualified, and large amount of waste water is directly discharged tothe ocean, Bohai Bay, without treatment. This will cause hidden danger for local area.

(1000ton)

200

186

150
100

106 103130 137

146 143

137

133
133

50
0

Fig.3 Surface water classification in 2009
Fig.4 COD emission amount in Tianjin
Source: Tianjin Statistical Year Book 2010

Figure 4 shows the COD emission amount from 2002 to 2009. Limited to data availability, Tianjin only use
COD in water pollution monitoring, this paper uses COD as the water pollutant control index in simulation. From
2001, Tianjin government has put proposals to improve water quality, therefore, with the economic rapid
development, COD amount has been controlled stably, and the trend is declining. However, the total COD amountand water quality still need to be improved badly. Tianjin government has proposed to reduce and control COD
amount in development plant until 2020.

2-4

Reclaimed water utilization situation

Furthermore, waste water reuse situation has just started in this area; the reclaimed water reuse rate is really low,
only 2.01% of reclaimed water is used in Tianjin. While the waste water disposal rate is 72.40%, a large amount oftreated waste water has not been used. Compared with Beijing, the reclaimed water reuse rate is 57.55%, there is alarge gap of reclaimed water utilization between these 2 Adjacent areas. It also demonstrates that there is large
potential to use reclaimed water in Tianjin.
Tianjin government also realized the importance to use recycle water in improving water quality and saving
water. Local government established a 10 years target to increase reclaimed water recycle rate to 50-60% in 2020.
Table1. Reclaimed water utilization (2009) units:( 10,000ton)

Total amount ofwater resource

waste water
discharged

sewage disposal
amountTianjin

15.24

8.23

5.96

sewagedisposalrate
72.40%

Beijing

34.2

13.21

10.43

78.92%

reclaimed water
utilization
amount0.12
6

reclaimed water
utilization rate
2.01%
57.55%

Source: Tianjin Water Bureau Statistical Year Book 2010, Beijing Water Bureau statistical Year Book 2009

From the current situation analysis, we can see that Tianjin water supply structure need to be perfected; over
70% of surface water in Tianjin is in inferior V level, water quality is not well; and waste water treatment coverageproportion still needs to be improved, reclaimed water utilization rate is low, 2.01%.
With the rapidly regional development, water scarcity is intensifying and water pollution is deteriorating. Thus,
it is important to research on waste water utilization in order to solve water shortage and water pollution problems.

3.

Research model construction

3-1 Case setting
In order to achieve sustainable development in catchment area, water quality should be improved along withwater resources saving. Since Tianjin government use COD as the major water quality control index, we adopted
COD to control the water environment from 2010 to 2020, 25% decrease in 2020 compared with that in 2010.
Aims to find out the contribution of reclaimed water to economic development, we set case 50, case 60, case 70
and case 80 to observe the total GDP amount and developing trend. Case 50 means 50% of sewage is reused asreclaimed water in 2020. Furthermore, we find out the maximize reclaimed water rate can be achieved is 75%,
therefore, we added 2 cases, Case 65 and case 75 in analysis. There are 5 different cases in evaluated in this paper.

3-2 Region Classification
Regards to the simulation framework, the catchment area is divided into 11 areas based on these administration
division and regional plan.
Table2. Tianjin’s regional division
Index

Name

Distinct

Index

Name

1

Central Urban
Area

Heping District3

Dongli District

Hedong District

4

Xiqing District

2

Binhai New
Area

Hexi District

5

Jinnan District

Nankai District

6

Beichen District

Hebei District

7

Wuqing District

Hongqiao District

8

Baodi District

Tanggu District

9

Ninghe County

Han'gu District

10

Jinghai County

Dagang District

11

Jixian County

3-3 Water supply and demand classifcation
And the water supply is divided into two types, clean water and reclaimed water. Water demand resource isseparated into 2 groups: household living water and industry water, and industry are divided into Primary industry,
secondary Industry and Tertiary Industry.

3-4 Reclaimed water treatment technology choice(1) Technology A
Technology A is Double membrane technology which is used in Beijing development area in China. This
technology uses skill “MF(Micro Filtration) +RO(Reverse Osmosis)” in waste water treatment. This technology’s
merits including large sewage treatment capacity, high water disposal rate (≥75%), and low operation cost. Compare
to technology B, its treatment capacity is larger, but the reclaimed water recycle rate and quality is lower.
(2) Technology B
Technology B is Ceramic membrane water treatment system. Japan has advanced waste water treatment
technology, especially in reclaimed water utilization area. Ceramic membrane water treatment which is developed by
Metawater.co.ltd, has high water quality treatment ability. The advantages including stable operation with inferior
input water; high water resource recycle rate which is over 90%; low operation cost; and easy to be cleaned.
However, the treatment capacity of waste water is small. Unit disposal cost is higher than Double membrane
technology in producing reclaimed water.

4.

Model structure

4-1

Objective function

The objective function was constructed to maximize the total GDP over the target term (t=11) in order todetermine an optimal policy.
(1)
MAX ∑ GDP(t)4-2Reclaimed water cycle balance model

Total water supply amount is:WS(t) = ∑ ∑(t) + ∑ ∑WS(t): water supply in time t;(t): water supply from reclaimed water.
The Water demand amount is:(t) + ∑∙
WD(t) = ∑ ∑( )+ ∑(t)(2)(t): water supply from clean water;( ): clean water supply of living water.
∙(3)

WD (t): Water demand in time t;: Coefficient of water demand of industry m in region j;(t): Production of industry m in the area of region j;
WS(t) ≥ WD(t)We assumed that the total sewage amounts except Primary industry have been disposed in sewage plant, including
existing sewage plant and new established sewage plant. Therefore, the reclaimed water amount is decided by new
established sewage plant, it has new technology to provide reusable water for Primary and Secondary industry.
( , )+ ∙RW(t) = ∑ ( ∙(, )(4)RW(t): Reclaimed water amount provided by sewage plant;: Reclaimed water recycle rate of technology A;: Reclaimed water recycle rate of technology B;( , ): Water amount treated by new sewage plant A in region j;( , ): Water amount treated by new sewage plant B in region j;

4-3

Water Pollutant Flow Balance Model

The total water pollutant amount of COD is discharged by economic and social activities:( )TP ( ) = ∑ ∑∙(5)

TP ( ): The total net load of water pollutant COD at time t: Coefficient of water pollution of industry m in region j;: Coefficient of water pollution of living water in region j;

4-4

Social-Economic model

In assumption, the new established sewage plant can provide reclaimed water. The sewage plant investment isproved by financial support and other social sources. The following is flow balance in the commodity market:
X(t) ≥ A ∙ X(t) + C(t) + I(t) + B ∙+ ( )+ ( )(6)X(t): Total product of industry in the study area(en);A: Input-output coefficient matrix (ex.);
C(t):Total consumption at time t(en);I(t): Total investment at time t(en);B : Column vector of m-th coefficient that induced production by construction of sewage plant (ex);I : Total investment for construction of sewage plant (en);e(t): Column vector of net export(en.);T(t): Column vector of transfer product between provinces in China(en.).

5.

Simulation Results Analysis
In this study, 5 scenarios are established to evaluate the contribution of reclaimed water to economic development

under COD constraint. The following results can be achieved:

5-1

Objective function

Under the water pollutant constraint, as well as the new sewage plant construction encouragement policy eachyear, GDP in Tianjin can get steady improvement since 2010. Between cases 50 to 75, there is a quick increase fromcase 50 to 60; the contribution of reclaimed water to economic is significant. The maximize total GDP can be got is11679.87 billion Yuan, 368.65 billion more than case 50. Although the top recycle rate of reclaimed water is 75%,
total GDP is declined. Therefore, we chose case 65 as the optimal plan for sustainable development in the target area.
116798.74
116461.30
116305.55
116042.71

117000116000115000114000113112.20

113000Total GDP
from 2010
to 2020112000

11500
11000
10500
10000
9500
9000
8500
8000

(100million Yuan)(100 million Yuan)

118000case50case60case65
case70case75111000case50 case60 case65 case70 case75
Fig.5 Total GDP of case 50 to case 75

Fig.6 GDP changing trend from 2010 to 2020

From the GDP increasing trend of case50 to 75, when we introduced new technology, the GDP increasing rate in
the former 5 years is higher than latter. Especially, in case 50, GDP decreases since 2015. This demonstrates that thecurrent technology and sewage plant cannot provide enough incentive power for both economic and environmental
improvement.

5-2

Reclaimed water utilization trend

Through simulation, we get the reclaimed water utilization potential in Tianjin from 2010 to 2020. With theeconomic development and financial support in research area, reclaimed water facilities are established and the total
reclaimed water usage amount is growing significantly.
The total reclaimed water amount is increased from case 50 to case 75. In case 65, the total amount of reclaimed
water can be provided from 2010 to 2020 is 29838.62 million tons.
30000
25000
20000

Total
SewageAmountReclaimed
Water
AmountFig.7 Recycle trend of sewage water from 2010 to 2020

(Billion m3)(Billion m3)

80000
70000
60000
50000
40000
30000
20000
10000
0

15000
10000
5000

Clean
Water
SupplyReclaimed
Water
Supply0

Fig.8 Reclaimed water substitution trend from 2010 to 2020

Figure 7 shows the recycle rate of sewage water from 2010 to 2020 in case 65. Since the reclaimed water is
produced by new sewage plant in assumption (which is almost the reality in Tianjin city, in 2009 only 2.01% ofreclaimed water is used), waste water recycle rate is increasing continuously in the 11 years, and the waste water
treated by new sewage plant can substitute the existing old sewage plant step by step. In 2010, only 1.54% watersupply comes from reclaimed wastewater, and in 2020, its percentage rises to 17.46% while economic development
and environmental protection. In 2020, total water demand is 27854.57million tons, and reclaimed water can save
4689.20 million tons clean water for Tianjin city.
From the above figure, we can see the reclaimed water recycle can get continue development if we construct thenew sewage plant with technology A and B, for their high waste pollution disposal ability and financial support. In
2020, total sewage amount is 7214.15 million tons, and 65% waste water can be recycled by new sewage plant, also
this can contribute a lot to water pollutant declination. There is a large potential to utilize and adopt new technologies
in Tianjin city to achieve sustainable development.

5-3 New sewage plant construction and distribution(100 million Yuan)

Also, from scenarios, we can get the distribution of new sewage plant in 11 regions of Tianjin. From 2010 to2020, there will be 42 plants being built. Regions with high population aggregation and economic development will
construct more sewage plant in the long run, such as the central urban area and Binhai New Area. Also, regions thatare short of wastewater disposal capacity will introduce new sewage plant at first, such as Beichenand Jinghai.
The current sewage disposal capacity in Tianjin is the basis for constructing new sewage plant in simulation. The
simulation chooses to build new sewage plant in these50
areas lack of sewage disposal ability. Also, the newsewage plant construction is constrained by local
40
government
financialcapacityandindustry’s
30
development.
The total budget is 4.29 billion Yuan from 2010 toTechnology
20
A Investment
2020, only 0.39 billion Yuan’s investment each year. And
Technology
in the former years, sewage plant with technology B is
10
B Investment
constructed more than that with technology A. In the latter0
5 years, the investments between 2 technologies arealmost even, they have their own advantages in providing
reclaimed water.
Fig.9 Financial budget of case 65
From this simulation results, we can also give specific policy proposals in constructing new sewage plant andadopt which kind of technology, in order to prompt reclaimed waste water reuse and achieve economic optimal
development.

6.

Conclusion

When we adopted a policy that introduces new technology to increase reclaimed water recycle in order to savewater resource and improve the water quality, the policy was proven to be an effective tool to achieve the sustainable
development target in the catchment area.
In short, this paper holds on that:(1) Reclaimed water recycle can be an effective method to save water resource, reduce water pollutant andimprove economic development in the catchment area;(2) New technologies adopted from China and Japan can provide sufficient reclaimed water production capacity
to achieve the local government reclaimed water utilization plan (50-60% reclaimed water recycle rate). Moreover,
the recycle rate can achieve 75%, while 65% recycle is considered to be the optimal choice for sustainable
development.
(3) Specific sewage plant construction plan is provided for local government policy references, including thetechnology choice and financial budget input etc.
In spite of these implications, this research has some limitations which call for follow-up research. First, thisresearch needs to put water price of difference water supply sources in consideration; furthermore, specify watersupply sources, such as water transferred from other provinces, rain water and sea water; classify the water demandof reclaimed water, etc.