Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006.  http://hdl.handle.net/1860/732The complicated floating-bed technique is an effective method for the non-point sources(NPS) pollution control. Suitable aquatic plants are selected and used to build the complicated floating-beds. They were applied for controlling NPS pollution in the pre-reservoir project in Lake Tai basin of China.
Colocasia esculenta(Linn.) Schott, Sagittaria sagittifolia Linn, Eleocharis dulcis Trin.ex Henschel,Oenantha javanica(Blume)DC, Ipomoea aquatica Forst, and Ganna generalis Balier are the common aquatic vegetable, ornamental flower in the area of Taihu lake. The removal rate of nitrogen and phosphorus by those plants at light eutrophicated level in summer and autumn was studied. They were selected as floating-bed plants for pre- reservoir project.
This paper proves that the Ipomoea aquatica Forst has better removal effect on total phosphorous (TP)(30-81%) and Colocasia esculenta(Linn.) Schott on total nitrogen (TN)(62-67%).
The floating-bed was applied in the pre-reservoir non-point pollution control project in the plain river network at Yixing County in Lake Tai basin. The effect of purification was very obvious. The complicated floating-bed was more effective than the previous plane floating-bed in the removal of TN and TP. This study can provide the useful information in the non-point sources pollution control and the ecological rehabilitation of rivers and lakes in genera

Wu, Xiaomin

Zhang, Yimin

Zhang, Yongchun

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Proceedings of the 7th International Conference on HydroScience and Engineering 
Philadelphia, USA September 10-13, 2006 (ICHE 2006) 
ISBN: 0977447405 
 
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College of Engineering 
 
 
 
 
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APPLICATION OF COMPLICATED FLOATING-BED FOR 
PRE-RESERVOIR NON-POINT SOURCES POLLUTION CONTROL 
PROJECT  
 
 
Yimin Zhang1  Xiaomin Wu2  Yongchun Zhang3  
 
 
ABSTRACT 
 
The complicated floating-bed technique is an effective method for the 
non-point sources(NPS) pollution control. Suitable aquatic plants are selected 
and used to build the complicated floating-beds. They were applied for 
controlling NPS pollution in the pre-reservoir project in Lake Tai basin of 
China. 
Colocasia esculenta(Linn.) Schott, Sagittaria sagittifolia Linn, 
Eleocharis dulcis Trin.ex Henschel,Oenantha javanica(Blume)DC, Ipomoea 
aquatica Forst, and Ganna generalis Balier are the common aquatic 
vegetable, ornamental flower in the area of Taihu lake. The removal rate of 
nitrogen and phosphorus by those plants at light eutrophicated level in 
summer and autumn was studied. They were selected as floating-bed plants 
for pre- reservoir project.  
This paper proves that the Ipomoea aquatica Forst has better removal 
effect on total phosphorous (TP)(30-81%) and Colocasia esculenta(Linn.) Schott on 
total nitrogen (TN)(62-67%). 
The floating-bed was applied in the pre-reservoir non-point pollution 
control project in the plain river network at Yixing County in Lake Tai basin. 
The effect of purification was very obvious. The complicated floating-bed was 
more effective than the previous plane floating-bed in the removal of TN and 
TP. This study can provide the useful information in the non-point sources 
pollution control and the ecological rehabilitation of rivers and lakes in 
                                                        
1 Associated Researcher, Nanjing Institute of Environmental Science,SEPA,Nanjing,210042,PRC,  
(zhangymzym@163.com , yimin@nies.org) 
2 Associated Researcher, Nanjing Institute of Environmental 
Science,SEPA,Nanjing,210042,PRC,(wxm@nies.org) 
 1 
3 Researcher, Nanjing Institute of Environmental Science,SEPA,Nanjing,210042,PRC(zyc@nies.org) 
general. 
 
KEY WORDS 
 Floating-bed; Aquatic plant; Non-point pollution; Pre-reservoir; plain river 
network 
 
1. INTRODUCTION 
 
Due to the rapid growth of population and quick development of social 
economy in the area of Lake Tai, inadequate environmental protection and 
pollution control has become obvious. The waters and river system of Lake 
Tai Basin have been polluted seriously and the eutrophication is aggravated 
continuously. This endangers the sustainable development of society and 
human health. The proportion of non-point source(NPS) pollution has 
exceeded the point source(PS) pollution and becomes the major pollution. 
The control and prevention of NSP now rises to be the most urgent problem. 
Numerous studies have shown that the pre-reservoir technology is a 
local adjusted measure of water pollution abatement(Klaus Pütz, et al,1998), 
which can effectively control NSP pollution in lakes and has an extensive 
application prospects. The pre-reservoir technology for NSP pollution control 
has been proven applicable in Lake Tai Basin, and the pre-reservoir 
intensified purification program(Zhang Yimin et al.,2003) specifically 
designed for the area of Lake Tai also has been drawn out. In order to 
improve the effect of pre-reservoir nutrients removal in deep-water area, the 
biologic floating-bed technology (Akiram,et al, 2000, Song Xiangpu,et 
al.,1991) will be adopted. Suitable aquatic plants were selected and 
complicated floating-beds were built up. They were applied for the 
pre-reservoir project in Lake Tai Basin of China. 
The complicated floating-bed, which is composed three-dimensional 
floating bed, is a cancellate space frame made of bamboo. The plants are put 
at the nodes of the upper level with string bags that are bred with snail and 
mussel fixed at four sides or angles of the frame. Linear polypropylene 
material is hanged from the lower part of the frame The structure of monomer 
and joining of the floating bed is shown in Fig1 and Fig2. It is more effective 
than the previous plane floating-bed in the removal of TN and TP.  
 
 2 
     
 Fig 2 Joining of the floating bed 
 FOR PLANT SELECTION 
ct the plants with better removal 
ix kinds of plants were tested, they were :Canna generalis 
Baile
ulcis Trin.ex Henschel, Oenanthe javanica (Bl.) Dc.,Ipomoea aquatica Forst.  
ake Tai. Average biomass is 1.0-1.5kg/m2.Covered with transparent roof in 
Test periods were from Aug. 3rd to Sept. 8th 
 summer, Sept. 25th to Nov. 2nd in autumn, and Nov. 2nd to Nov. 29th.  
TN , 
low analyzer, COD with permangani- 
metri
.  
 
 
Fig 1 Monomer of the floating bed 
 
2.  PILOT EXPERIMENT
 
2.1 Materials and Methods 
 
The purpose of experiment was to sele
effect and higher economic value. 
S
y,Colocasia esculenta (L.) Schott;Sagittaria sagittifolia L, Eleocharis  
d
They are common aquatic vegetable or the ornamental flower in the basin of 
L
the open air. 200L water tanks. 
in
ammoniacal nitrogen(N-NH3) and TP were measured with SKALAR 
(Netherlands) SAN++ continuous f
c method(SEPA,1998) 
 
2.2 Results and Discussion 
 
The growth and the removal rate of nitrogen and phosphorus at light 
eutrophicated level of six plants were studied in summer and autumn by a 
pilot test. They were selected as floating-bed plants for pre-reservoir project
 
 
 
 
 3 
 
Table.1 Water chemistry measured in summer and fall experiments 
    Items Water temp. TP PO
Exp. (℃) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) 
4
3－
-
TN NH4
＋-N
 
NO3
－ COD 
Exp n 
Summer 30±1 
1.315±
0.272 
1.013±
0.190 
2.549±
0.421 
1.619±
0.345 
0.016±
0.005 
17.381±
1.369 
. i
Exp n 
Aut n 25±1 
0.407±
0.05 
0.317±
0.043 
1.747±
0.606 
0.498±
0.198 
0.457±
0.256 
13.699±
1.594 
. i
um
-150
-100
-5
5
2 0d 25 d
Time(d)
at
e
0
0
0
0
100
d 5d 1 15d 20d d 30d 35
R
em
ov
al
 r
(%
)
CK
 Canna generalis Bailey
Colocas
Schott
ia esculenta (L.)
Sagittaria sagittifolia L
Eleochar
Hensche
is du
l
lcis Trin.ex
Oenanthe java )
Dc
nica (Bl.
Ipomoea aquatica Forst 
 
 
 
Fig.3 TP removal rate in summer exp 
-150
-100
-50
0
50
100
0d 8d 18
d
28
d
38
d
48
d
58
d
Time(d)
R
em
ov
al
 R
at
e(
%
)
CK
phytomeliorated terricolous
Canna generalis Bailey
Colocasia esculenta (L.)
Schott
Sagittaria sagittifolia L
Eleocharis dulcis Trin.ex
Henschel
Oenanthe javanica (Bl.) Dc
Ipomoea aquatica Forst 
 
 
 
Fig.4TP removal rate in early autumn exp 
 4 
 .
-50
0
50
100
0 2d 5d 10d 15d 20d 25d 30d 35d
Time(d)
R
em
ov
al
 R
at
e(
%
)
CK
 Canna generalis Bailey
Colocasia esculenta (L.)
Schott
Sagittaria sagittifolia L
Eleocharis dulcis Trin.ex
Henschel
Oenanthe javanica (Bl.)
Dc
Ipomoea aquatica Forst 
 
 
.
-150
-100
-50
0
50
100
0d 3d 8d 13d 18d 23d 28d 33d 38d 43d 48d 53d 58d
Time(d)
R
am
ov
al
 R
at
e(
%
)
CK
 Canna generalis Bailey
Colocasia esculenta (L.) Schott
Sagittaria sagittifolia L
Eleocharis dulcis Trin.ex
Henschel
Oenanthe javanica (Bl.) Dc
Ipomoea aquatica Forst 
 
 
 
 
Ipomoea aquatica Forst showed a good P removal performance, 
TP:30% - 81%;Colocasia esculenta (Linn.) Schott had a good N removal 
effect, TN: 67% - 62%. 
 
 
Fig.5 TN  removal rate in summer exp 
Fig.6 TN removal rate in early autumn exp 
 5 
 6 
 
0
25
50
75
100
2-Nov 7-Nov 12-Nov 17-Nov 22-Nov 26-Nov
Date
R
em
ov
al
 R
at
e(
%
)
TN
TP
 
Fig. P and T e)Dc in late autumn exp 
th 
d 
 summer experiment, the removal rate of Ipomoea aquatica Forst > 
Canna generalis Bailey, Eleocharis dulcis Trin.ex Henschel and Colocasia 
esculenta (Linn.) Schott > Sagittaria sagittifolia L. and Oenanthe javanica 
(Bl.) Dc. 
In early autumn experiment, the removal rate of Colocasia esculenta 
(Linn.) Schott >Sagittaria sagittifolia L., Canna generalis Bailey and 
Ipomoea aquatica Forst, >Eleocharis dulcis Trin.ex Henschel and Oenanthe 
javanica (Bl.) Dc.. 
Ipomoea aquatica Forst (better TN removal) and Colocasia esculenta 
(Linn.) Schott(Forst (better TP removal) , Oenanthe javanica(Bl.)Dc were 
selected. They have higher purification efficiency, aesthetic value, are easy 
for long-time management, and can ensure green plants year-round 
circulation. 
 
3.  APPLICATION IN THE PRE-RESERVOIR PROJECT 
 
The floating-beds were applied in the Pre-reservoir Non-point Sources 
P  
N removal rate by Oenantha javanica(Blum7  T
 
Oenantha javanica (Blume) DC had low removal rate in bad grow
status. removal rate of TP and TN is about 50% in the research on Nov.22n
-29th . 
In
ollution Control Project in the area of plain river network- in Yixing County
of Lake Tai Basin, southeast of China. They were assembled first, and then 
collo s 
.  
 field test in the river was set up according to Fig 8..Parameters(TN 
and T
Note: FB means floating-bed. .# means the monitoring point. 
oncentrations of TP and TN in water were reduced by the 
composite tridimensional floating-bed. The plants used in the floating-bed are 
a (Bl.) Dc and Oenanthe javanica (Bl.) Dc. The removal 
te of TP and TN is about 30-50% and 50-70%(Fig9-10) respectively. But 
the re
cated around an island and in the river. Field effect of the floating-bed
was analyzed in the river. The effect of purification by those plants was very 
obvious
 
3.1  Methods 
 
The
P) were determined from April to June. 
 
 
 
 
 
 
 
 
 
 
 
 
Fig 8  Layout of the floating-bed in the field test  
 
3.2Result and Discussion 
 
The c
Oenanthe javanic
ra
sults of plane floating-bed were not satisfied. 
 
5 monomer 5 monomer 
1＃ 
  
3＃ 
4＃ 
5＃Complic. FB  
 
Clapboard
 
Plane FB  
 
Plane FB 
 
Complic.FB  
 
Canna G.B
 Oenantha / Ipomoea
Canna  
2＃
Oenantha / Ipomoea
 7 
0.000
30/4 10/5 20/5 30/5
Date
0.050on
ce
n 0.100
0.1
TP
 C
at
io
n 
m 50
0.200
tr
g/
l）
 Floating-bed of Oenanthe javanica (Bl.)
Dc(inflow)
Floating-bed of Oenanthe javanica (Bl.)
Dc(outflow) - Canna generalis Bailey(inflow)
Floating-bed of Canna generalis
( )
 Floating-bed of Oenanthe javanica (Bl.)
Dc(inflow)
Floating-bed of Oenanthe javanica (Bl.)
anna generalis Bailey(inflow)Dc(outflow) - C
Floating-bed of2.50/l）  Canna generalisBailey(outflow)
0.50
1.00
2.00
N 
Co
nc
en
tr
a
mg
1.50tio
n（
0.00
30/4 10/5 20/5 30/5 14/6
Date
T
   
Fig9  Removal effect of TP by the     Fig10 Removal effect of TN by the 
composite tridimensional floating-bed   composite tridimensional floating-bed 
0.00
0.50
1.00
1.50
2.00
2.50
April30 May10 May 20 May 30
Date
TN
 c
on
ce
nt
ra
ti
on
（
mg
/l
）
Inflow（Oenanthe javanica (Bl.) Dc）
Inflow(Canna generalis Bailey)
Outflow (Canna generalis Bailey)
 
Fig11  Removal effect of TN by the plane floating-bed 
 
 
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.180
0.200
April30 May10 May 20 May 30
Date
TP
co
nc
en
tr
at
io
n（
mg
/l
）
Inflow（Oenanthe javanica (Bl.) Dc）
Inflow(Canna generalis Bailey)
Outflow (Canna generalis Bailey)
 
Fig12  Removal effect of TP by the plane floating-bed 
 
he biological floating-bed has shown some removal effect to the 
 
T
 8 
nutrient in the water but improvement still needs to be made. Natural 
condition and the inflow load can affect the results a lot. 
 
4.  CONCLUSION 
 
Biological floating-bed can be applied widely in the polluted water 
bodies such as lake ,river, reservoir and so on, because of its high removal 
effect of TN and TP. In the deeper water (>1m), due to its low transparency, 
submerged plants don’t grow. Aquatic vegetables combining the water 
purification with the production practice and integrated utilization, are easy to 
run and manage he heavy 
metal polluted water if they are for food. 
ification function of 
plants in the water at most. 
s the scientific basis for non-point sources pollution 
control and for the ecological rehabilitation of rivers and lakes in general. 
Klaus Pütz, Jürgen Benndorf. 1998. The importance of pre-reservoirs for the 
contro
ial Substrate.1999. Acta Scientiarum Naturalium 
Unive
ure 
of Rice in Natural Waterspace [J]. Chinese Agricultural Sciences, Vol. 14, No. 
tate Environmental Protection Administration of China.1998. Monitoring 
Wang Xuming et al.1999. Study on Wastewater Purification by Oenanthe 
 for long-term. However, they are not suitable for t
 
The application of floating-bed, particularly, the composite tridimensional 
floating-bed, can overcome the problem that aquatic plants are not active in 
general in the deeper water and can fully develop the pur
This study provide
 
REFERENCES 
 
Akiram, Fumitakek, Waichia, et al. 2000. Plant production and water 
purification efficiency by rice and umbrella plants grow in a floating culture 
system under various water environmental conditions [J].J.Fac Agr. Kyushu 
Univ, Vol. 45, No. 1, pp. 28-38. 
l of eutrophication of reservoirs. Water Science and 
Technology.Vol.37, No. 2, pp.317–324.  
Liu Shuyuan et al.1999.Study on Ultrophication Water Purification by 
Soilless Plants with Artific
rsitatis Pekingensis, Vol.35, No. 4, pp. 518-522. 
Song Xiangpu, Ying Huodong, Zhu Min et al.1991. Study on Soilless Cult
4, pp 8-13. 
S
and Determination Methods for Water and Wastewater, Beijing: China 
Environmental Science Press. 
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Javanica. Agriculture Environmental Protection, Vol. 18, No. 1, pp. 34-35. 
You Wenhui. 2000. Study on the Polluted Water Purification by Aquatic & 
e Application of the Pre-reservoir 
Economic Plants. Journal of East China Normal University, Vol., No. 1, pp. 
99-102. 
Zhang Yimin et al.2003. Discussion on th
in the Nonpoint Pollution Control of Lake Tai Basin. Environmental 
Pollution and Control. Vol. 25, No. 6, pp.342－344 
 
 10


Application of complicated floating-bed for pre-reservoir non-point sources pollution control project

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Application of complicated floating-bed for pre-reservoir non-point sources pollution control project

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