The paper indicates that Pistia stratiotes were used for wastewater treatment about twenty days with 0 individual/tank, five individuals/tank, seven individuals/tank, nine individuals/tank. Every experiment was conducted three times in the same way with 140 L for each tank. The experimental result shows that the amount of Pistia stratiotes increases and reach the highest quality in Treatment 3 on the 15th day.
Trang 1THE USE OF PISTIA STRATIOTES IN DOMESTIC SEWAGE WATER TREATMENT
FROM NATURAL LAKES AND PONDS AT KHANH AN COMMUNE,
AN PHU DISTRICT, AN GIANG PROVINCE
Nguyen Tran Thien Khanh1, Le Cong Quyen2, Nguyen Xuan Lan2
1
An Giang University, VNU – HCM
2
Center for Natural Resources and Environment Monitoring and Technology, An Giang
Information:
Received: 25/04/2019
Accepted: 27/09/2019
Published: 11/2019
Keywords:
Pistia stratiotes, domestic
sewage, Khanh An lakes and
ponds
ABSTRACT
The paper indicates that Pistia stratiotes were used for wastewater treatment about twenty days with 0 individual/tank, five individuals/tank, seven individuals/tank, nine individuals/tank Every experiment was conducted three times in the same way with 140 L for each tank The experimental result shows that the amount of Pistia stratiotes increases and reach the highest quality in Treatment 3 on the 15th day The treatment performance
of BOD5, COD, TKN, and TP content of Treatment 3 using Pistia stratiotes
on the 20th day is high varying from 63.9 % to 96.4 %
1 INTRODUCTION
Today, Khanh An commune, An Phu district,
An Giang province applies the method of
digging pond to treat domestic wastewater with
aquatic plants with an area of 600 m2 However,
up to now, the domestic waste water from the
pond after being discharged into the Hau River
still exceeds QCVN 14: 2008 many times
Sinha, S et al (2006) stated that Pistia stratiotes
is a species capable of removing organic
compounds in wastewater Nguyen Thanh Loc,
Vo Thi Cam Thu et al (2015) showed that
treatment performance of Pistia stratiotes for
water quality parameters such as: TKN, TP,
BOD5 and COD respectively at 65,5 % ,
95,81%, 67,20% and 74,73%
Pistia stratiotes contains different types of
alkaloids: glycosides, flavonoid and
phytosterol Leaf and stem contain 1,4%
protein, 0,3% fat, 2,6% carbohydrate, 0,9% raw fiber and 1,9% mineral substances(mostly kali and phosphorus), the leaf is rich in vitamins A&C (Khare, C.P 2005) Mohapatra S.B and
Patra A.K, (2014) concluded that P stratiotes
Can be used as a main raw material in mixing feed for carp
In order to provide more solutions to improve the water in Khanh An lake, it is necessary to study the density of Pistia stratiotes
2 RESEARCH METHOD
2.1 Seedling preparation
Pistia stratiotes collected from waterbody in
An Giang province Pistia stratiotes seedling
after collect is washed thoroughly with clean water Then choosing the strong, healthy plants, pest-free and relatively similar in height and growth period The roots will be cut, leaving
Trang 20.5 cm from the root and cut off the small
seedlings The plants will be put into
rectangular plastic containers containing clean
water with a volume of 157.5 L (length 0.7 m x
width 0.5 m x height 0.45 m) in 2 days (Nguyen
Thanh Loc et al., 2015)
2.2 Waste water preparation
Wastewater is transported from Khanh An Lake
to the testing location and immediately put into
the testing units (transportation time is about 2
hours)
2.3 Experimental arrangement
The experiment was arranged in a completely
randomized manner with 4 treatments with
different density of Pistia stratiotes densities: 0
individual / tank, 5 individuals / tank, 7
individuals / tank, 9 individuals / tank Each
treatment was set up for 3 times with the
amount of waste water arranged in each tank of
140 L The experimental arrangement was 20
days (Théophile Fonkou et al 2002) No
additional waste water was added during the
experiment
2.4 Method of collecting and analyzing
indicators
2.4.1 Collecting and analyzing water samples
Water sample analysis criteria includes
biological oxygen demand (BOD5), chemical
oxygen demand (COD), Total Kjeldahl
Nitrogen (TKN), Total phosphorus (TP) were
collected and analyzed according to standards APPA, AWWA and WEF (2005) The duration
of collecting sampling period is 5 days per time (the first time is from the beginning of experiment arrangement) Water samples are analyzed immediately after collection; In case
of unsuccessful analysis, the sample will be stored in accordance to the standard of TCVN 6663-3 : 2008
2.4.2 Collecting and analyzing Pistia stratiotes samples
Pistia stratiotes in all 3 treatments were
collected based on two indicators including density and number of leaves per individual
The sampling period of Pistia stratiotes is the
same as the water samples (Théophile Fonkou
et al 2002)
2.5 Data processing methods
The data was synthesized using MS Excel software First, the variance is analyzed then tested via Duncan using SPSS 18.0 software to evaluate the ability of water quality treatment
indicators and the quantity of Pistia stratiotes in
the experimental treatments
3 RESULTS AND DISCUSSION
3.1 Characteristics of input waste water
The analysis of the input wastewater shows that the concentration of pollutants in the
wastewater is quite high as shown in Table 1
Table 1 Characteristics of wastewater used in the experiment
(*) TCVN 6980: 2001, Q > 200 m 3 /s, F1
Trang 3TKN and TP indicator respectively are 15.4 ±
0.3mg/L and 3.63 ± 0.13mg/L lower than
However, BOD5, and COD indicators
respectively are 105.67 mg/L, 206.33 ±
9.07mg/L much higher than allowed by law
Therefore, the wastewater does not meet the
standards and is required more treatment before
being discharged
3.2 Quantity growth of Pistia stratiotes
The results in Figure 1 show that the number of
Pistia stratiotes in Treatment 1, Treatment 2
and Treatment 3 increases over time and reaches the highest value on the 15th day From
the 15th to the 20th day, the number of Pistia
stratiotes is decreasing This is due to the fact that the Pistia stratiotes starts to die at this
stage because the nutrient content in water is
very low while the quantity of Pistia stratiotes
is high
The difference in the number of Pistia stratiotes
in the treatments is statistically significant at the significance level ( = 0.05)
Figure 1 Growth in the quantity of Pistia stratiotes over time
3.3 Waste water treatment capacity of Pistia
stratiotes
3.3.1 The treatment performance of BOD5
content using Pistia stratiotes over time
The results in Table 2 show that BOD5 content
decreases along with the experiment time All 3
treatments using Pistia stratiotes to treat BOD5
content in water at day 20 was lower than
QCVN 14: 2008 / BTNMT (column A)
Meanwhile, control treatment does not arrange
Pistia stratiotes, BOD5 content is at high level,
exceeding QCVN 14: 2008 / BTNMT The content of BOD5 in different treatments was statistically significant ( = 0.05)
Treatment performance of BOD5 content in
water in 3 Treatment using Pistia stratiotes at
day 20 was quite high: Treatment 1: 80.1%, Treatment 2: 84.2% and Treatment 3: 88%
Trang 4Table 2 BOD5 content of treatments over time (mg/L) Treatment Day 0 Day 5 Day 10 Day 15 Day 20 (*) (**)
Control 105.7 ± 2.5a 93.3 ± 1.5a 82.3 ± 3.2a 75.3 ± 1.5a 68.0 ± 2.0a 35.6
30
Treatment1 105.7 ± 2.5a 86.3 ± 3.5b 57.7 ± 1.2b 37.3 ± 4.7b 21.0 ± 2.7b 80.1
Treatment2 105.7 ± 2.5a 84.7 ± 3.8b 55.3 ± 2.5b 35.3 ± 2.3b 16.6 ± 1.5c 84.2
Treatment3 105.7 ± 2.5a 74.7 ± 4.2c 45.7 ± 2.9c 31.0 ± 1.0c 12.7 ± 2.1d 88.0
Note: On the same column, values with different characters mean that the difference is statistically significant ( =
0.05); Average value ± Std
(*): Treatment performance of day 20 (%)
(**): QCVN 14:2008/BTNMT (Column A)
3.3.2 The treatment performance of COD
content using Pistia stratiotes over time
Table 3 shows the COD content at the 15th day
in Treatment 2, Treatment 3 and the 20th day in
3 treatments is lower than the permitted level of
TCVN 6980: 2001, Q> 200 m3 / s, F1 and the
wastewater is allowed to be discharged directly
to the receiving source The results showed that
Pistia stratiotes used organic matter to be
decomposed into an easily absorbed ion form for growth
The treatment performance of COD content in 3
treatments using Pistia stratiotes on day 20 was
quite high respectively Treatment1: 72%, Treatment2: 78.7% and Treatment3: 84.3%
This result is quite similar to the study of Nguyen Thanh Loc et al (2015) and Théophile Fonkou et al (2002)
Table 3 COD values of treatments over time (mg/L) Treatment Day 0 Day 5 Day 10 Day 15 Day 20 (**) (*)
Control 206.3 ± 9.1a 190.3 ± 3.5a 175.0 ± 4.6a 159.0 ± 1.0a 145.0 ± 4.6
a 29.7
70
Treatment1 206.3 ± 9.1a 149.0 ± 6.1b 98.3 ± 5.7b 86.7 ± 2.1b 57.7 ± 4.9
b 72.0
Treatment2 206.3 ± 9.1a 140.7 ± 6.4b 82.3 ± 3.2c 68.0 ± 1.0c 44.0 ± 3.0
c 78.7
Treatment3 206.3 ± 9.1a 116.3 ± 4.0c 55.7 ±2.5
d 45.3 ± 1.5 d
32.3 ± 2.5 d 84.3
Note: On the same column, values with different characters mean that the difference is statistically significant ( =
0.05); Average value ± Std
(*):Treatment performance of day 20 (%)
(**): TCVN 6980: 2001, Q > 200 m 3 /s, F1
Trang 53.3.3 The treatment performance of TKN
content using Pistia stratiotes over time
When comparing the results of the number of
Pistia stratiotes in the Treatments, it shows that
the amount of TKN content decreases, the
weight of the Pistia stratiotes individuals
increase along with the experiment time In
particular, in Treatment 1, the number of Pistia
stratiotes is the lowest, the treatment
performance of TKN content of Treatment 1 is
at 71.1% On day 20, it is at 71.1% In
Treatment 3, the number of Pistia stratiotes
increases a lot TKN content treatment efficiency reaches the highest in Treatment 3 at 83,6% This result is higher than stated in the study of Nguyen Thanh Loc et al., (2015) The difference in the ability of TKN content
treatment of Pistia stratiotes in the treatments is
statistically significant ( = 0.05) The data are shown in Table 4
Table 4 TKN values of the treatments over time (mg/L) Treatment Day 0 Day 5 Day 10 Day 15 Day 20 (*) (**)
Control 15.4 ± 0.3 a 13.73 ± 0.2 a 12.47 ± 0.4 a 11.60 ± 0.2 a 10.57 ± 0.2 a 31.4
35
Treatment1 15.4 ± 0.3 a 10.66 ± 0.9 b 7.40 ± 0.1 b 5.70 ± 0.4 b 4.45 ± 0.2 b 71.1
Treatment2 15.4 ± 0.3 a 10.47 ± 0.1 b 7.10 ± 0.2 b 5.31 ± 0.3 b 4.12 ± 0.3 b 73.2
Treatment3 15.4 ± 0.3 a 9.76 ± 0.3 c 6.52 ± 0.1 c 3.99 ± 0.1 c 2.52 ± 0.3 c 83.6
Note: On the same column, values with different characters mean that the difference is statistically significant ( =
0.05); Average value ± Std
(*):Treatment performance of day (%)
(*): QCVN 14:2008/BTNMT (column A)
3.3.4 The treatment performance of TP content
using Pistia stratiotes over time
Table 5 shows the change in TP content in
outlet wastewater compared to untreated input
wastewater This proves that aquatic plants play
an important role in phosphorus removal The
treatment performance of TP content of 3
Treatments with Pistia stratiotes at day 20 was
very high Treatment 1: 63.9%, Treatment 2:
74.7% and Treatment 3: 96.4% Meanwhile, in
the control treatment not using Pistia stratiotes,
the treatment performance of TP content is only
at 33.3% Thus, we conclude that aquatic plants take nutrients in wastewater to serve their growth and at the same time contributes to pollutants removal in the water The difference
in the treatment performance of TKN content of
Pistia stratiotes in the treatments is statistically
significant ( = 0.05)
Trang 6Table 5 TP values of treatments over time (mg/L)
Control 3.63 ± 0.13 a 3.24 ± 0.05a 2.86 ± 0.07a 2.56 ± 0.09a 2.42 ± 0.25a 33.3
6 Treatment1 3.63 ± 0.13 a 2.88 ± 0.12b 2.11 ± 0.08d 1.90 ± 0.15b 1.31 ± 0.18b 63.9
Treatment2 3.63 ± 0.13a 2.62 ± 0.13c 1.55 ± 0.17c 1.25 ± 0.03c 0.92 ± 0.12c 74.7
Treatment3 3.63 ± 0.13a 2.16 ± 0.03d 1.26 ± 0.09d 0.80 ± 0.09d 0.13 ± 0.04d 96.4
Note: On the same column, values with different characters mean that the difference is statistically significant ( =
0.05); Average value ± Std
(*):Treatment performance of day 20 (%)
(*): QCVN 14:2008/BTNMT (column A)
4 CONCLUSION AND
RECOMMENDATIONS
4.1 Conclusion
The number of Pistia stratiotes increases over
the experimental period and reached the highest
number in Treatment 3 on day 15
During the test, environmental factors decreases
over time The treatment efficiency of BOD5
content in water in 3 NT with Pistia stratiotes
arrangement at day 20 is quite high
respectively, Treatment 1: 80.1% to 88% The
highest treatment performance of COD content
in Treatment 3: 84.3% Treatment performance
of TKN content ranges from 71.1% to 83.6%
Finally, treatment performance of TP content is
very high in Treatment 1: from 63.9% to
96.4% Treatment 3 has the highest treatment
performance
4.2 Recommendations
It is very important to continue to research
domestic wastewater treatment in the lakes of
Khanh An commune, An Phu district, An Giang
province by Pistia stratiotes in continuous flow
system
REFERENCES
APHA, AWWA & WEF (2005) Standard
Methods for the Examination of Water and
Wastewater (20th ed), American Public
Health Association, Washington, DC
Khare, C.P 2005 Encyclopedia of Indian medicinal plants Berlin Heidelberg, Germany: Springer-Verlag p 372
Mohapatra S.B & Patra A.K (2014)
Evaluation of nutritional value of water lettuce (pistia stratiotes) meal as partial substitution for fish meal on the growth performance of cyprinus carpio fry
International Journal of Agricultural Science and Research (IJASR) ISSN(P): 2250-0057;
ISSN(E): 2321-0087 Vol 4, Issue 3, Jun
2014, 147-154
Nguyen Thanh Loc, Vo Thị Cam Thu, Nguyen Truc Linh, Dang Cuong Thinh, Phung Thi Hang and Nguyen Vo Chau Ngan (2015)
Evaluate the effectiveness of domestic wastewater treatment of some types of aquatic plants Can Tho University: Topic:
Environment and climate change (2015):
119-128
Sinha, S., A.K Gupta, K Bhatt, K Pandey, U.N Rai and K.P.Singh (2006) Environ
Monitor Assess., 80: 17-31
Théophile Fonkou, Philip Agendia, Ives Kengne, Amougou Akoa & Jean Nya, (2002) Potentials of water lettuce (Pistia stratiotes) in domestic sewage treatment with macrophytic lagoon systems in Cameroon Proceedings of International Symposium on Environmental Pollution Control and Waste Management 7-10 January 2002, Tunis (EPCOWM’2002), p.709-714