The document describes a study that examined using water hyacinth in constructed wetlands to treat domestic sewage in Nigeria. Water hyacinth was planted in 6 beds that received sewage from a university. Samples were taken weekly for 24 weeks. Results showed large reductions in key pollutants: color (100%), turbidity (92.95%), BOD (84%), TDS (88%), nitrates (76%), phosphates (87%), and E. coli (99.65%). Water hyacinth growth increased exponentially, with the largest growth and best sewage treatment in the last beds. The system provided effective and low-cost sewage treatment using a natural method.

1. Alternative Sewage Treatment Option:
The Effect of use of Water Hyacinth
(Eichornia crassipes) in the Treatment of
Domestic Sewage
A. E. Adeniran
Works & Physical Planning Department
University of Lagos, Nigeria
aadeniran@unilag.edu.ng
engrea@yahoo.com
1

2. Introduction
• Conventional sewage treatment plants have been found to fail
in the developing countries.
• They are expensive to construct, operate and maintain.
• Many of these treatment facilities, where available, have broken
down due to lack of maintenance
2

3. The result is polluted canals and
water streams
3

4. Constructed Wetland and Sewage Treatment
Constructed wetlands (CW), are now widely used
as an accepted method of treating wastewater
and are cheaper than traditional wastewater
treatment plants
• CW is appealing to developing nations in the
tropics due to the high rate of plant growth
(Kivaisi, 2001. Campbell and Ogden, 1999;
Gopal, 1999; Kadlec and Knight, 1995; Kadlec,
1995)
• Water Hyacinth sewage treatment plant as a form
of CW in improving the sewage effluent quality
parameters is examined here. 4

5. Introduction Continued
• We examined the effect of the growth of water hyacinth as a form
of constructed wetland with surface flow on selected sewage
quality parameters on weekly basis for a period of 24 weeks.
• Observation after 24 weeks show:
• 100% - Colour
• 92.95% - Turbidity,
• 84% - BOD
• 88% - TDS,
• 76% - Nitrate,
• 87% - Phosphate
• 99.65% - e-coli
• It is concluded that the use of water hyacinth plant on domestic
sewage pond is a viable and cheaper alternative method of
domestic sewage treatment
5

6. Innovation to Sewage Treatment:
The Water Hyacinth Option
• A water hyacinth based biological treatment plant
was designed and constructed at the Service Area
of University of Lagos .
• The plan and section through the treatment plant is
as shown below.
drain
drain
1720
drain
300
Effluent Point
sample
300 300 point E
A B C D E
7100
bed 5 bed 6
bed 4
in et pin
flun o t flo canl
whne wtehain bsdswepns
a r yc th ae e a od
g flo canl
whne wtehain bsdswg pns
a r yc th ae e ae od
sample 230m
10 m 200m
40 m 250m
50 m 250m
50 m
point D w rhain
a yc th
te
pn
lat
630
area
area
sample
point C
150 300 300
7000 150 8500 8500
circulation
circulation
BD1
E BD5 BD6 e et
E E
Existing drain
bed 3 BD BD3
E2 E BD4
E fflun
Sren(s egue
c e tel az)
7100
bed 1 bed 2 pin
ot
sample Inetio
cp n
point B
Ca br
hm e LNI UI A POI EFO PI TATRUH
OG D L RFL RMO HOG E
T N N
300
300
Existing drain
sample
point A
1850
(Influent Point)
sewer line
200mm
WATER HYACINTH BASED SEWAGE PONDS LAYOUT
6

7. Operation & Hyacinth Growth
• Domestic sewage, from the University
of Lagos sewer system, at a flow rate of
7.87m3/s (680m3/day) was introduced
into the beds.
• Water hyacinth plants (Eichhornia
crassipes) obtained from natural
specimens grown in polluted canal at
Iwaya, near the University of Lagos,
Nigeria were planted on the ponds
• Initially, a total of 15.6m3 of water
hyacinth was planted on the pond i.e.
an average of 2.6m2 per bed.
• The area covered by the water hyacinth
on each bed was measured weekly for
24 weeks from 18th March, 2010 to 31st
August, 2010..
7

8. Methods
OBSERVATIONS
• Samples of the sewage influent and effluent
were collected at Influent and Effluent Points on
a weekly basis
• Observation Period was from 18th March, 2010
to 31st August, 2010.
• The samples were analysed in the laboratory to
determine the level of concentration of the
observed parameters
• Also, the growth patterns of the water hyacinth
plants on each bed were monitored and
measured.
8

9. Water Hyacinth Growth Profile
Total Area Covered
• The growth profile of the water 400.00
hyacinth on the sewage ponds
350.00
300.00
is plotted against time.
Total Area Covered (Sq.m.)
250.00
• It is observed that the growth 200.00 Total Area Covered
profile follows an exponential
150.00
100.00
profile. 50.00
• The plant growth slowly in the -
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Time (Weeks)
14 15 16 17 18 19 20 21 22 23 24
first few weeks and then grow
exponentially until the 11th 70.00
Water Hyacinth Growth in Each Bed
week when the whole pond 60.00
Bed1
was covered with the plant 50.00
Bed2
Bed3
Bed4
Bed5
• It was observed that the Area Covered (sq.m.)
40.00
Bed6
growth pattern increased from 30.00
Bed 1 to Bed 6 just as the 20.00
quality of the sewage improved 10.00
-
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (weeks)
9

10. Colour
• The effluent colour improved from initial level of 195pcu to 0pcu in
week 19 and remain so until week 24.
• It was observed that the water hyacinth-based sewage treatment
plant was able to reduced the influent level for colour from average
of 209 pcu to 0 pcu at effluent point after 19 weeks
• 100% removal level was achieved for colour
Influent_Effluent Colour % Colour Removal
250.00 120.00
% Colour Removal
100.00
200.00
80.00
150.00
% R em o val
Colour (pcu)
60.00
Influent Colour
100.00 Effluent Colour
40.00
50.00 20.00
-
-
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (Weeks)
Time (Weeks)
Influent and Effluent Colour % Colour Removal
10

11. Turbidity
• The effluent turbidity improved from initial level of 100HTU to 64.2HTU
to 6.7 HTU at week 24.
• It was observed that the water hyacinth-based sewage treatment plant
was able to reduce the Influent Turbidity from an average of 93 HTU to
a final effluent level of 6.7 HTU
• 92.93% removal level for turbidity at the end of the 24 weeks
observation
Influent_Effluent Turbidity
100.00
140.00
90.00 % Turbidy Removal
120.00 Influent Turbidity 80.00
Effluent Turbidity
70.00
100.00
% Turbidity Removal
60.00
Turbidity (HTU)
80.00
50.00
60.00 40.00
30.00
40.00
20.00
20.00
10.00
0.00 -
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (Week) Time (Weeks)
Influent and Effluent Turbidity % Turbidity Removal
11

12. Biochemical Oxygen Demands (BOD)
• The effluent BOD improved from initial level of 508 to
83 mg/l.
• The average Influent BOD level of 513mg/l was
reduced to a final effluent level of 83mg/l
• 83.84% removal level for BOD was achieved.
% BOD Removal
180.0
100.00
160.0
90.00
140.0 80.00
70.00
120.0
% BOD Removal
60.00
BOD (mg/l)
100.0
50.00
80.0
Influent
40.00 % BOD Removal
Effluent
60.0
30.00
40.0 20.00
20.0 10.00
0.00
0.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Time (Days)
Time (Days)
Influent Vs Effluent BOD % TDS Removal
12

13. Removal of Nitrate
• The effluent Nitrate improved from initial level of 9.5
to 2.33 mg/l.
• The average Influent Nitrate level of 10.91mg/l was
reduced to a final effluent level of 2.33mg/l
• 78.64% removal level for Nitrate was achieved
Tnfluent_Effluent Nitrate % Nitrate
18.00 100.00
Influent_Nitrate
16.00 Effluent_Nitrate 80.00
14.00 60.00
12.00 40.00
% Nitrate Removal
Nitrate (mg/l)
10.00 20.00 % Nitrate
8.00
-
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
6.00
-20.00
4.00
-40.00
2.00
-60.00
-
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 -80.00
Time (Week)
Time (Week)
Influent and Effluent Nitrate % Nitrate Removal
13

14. Removal of Phosphate
• The effluent Phosphate improved from initial level of
20.60 to 2.60 mg/l.
• The average Influent Phosphate level of 21.75mg/l
was reduced to a final effluent level of 2.60mg/l
• 88.05% removal level for Phosphate was achieved
Influen_Effluent Phosphate % Phosphate Removal
30.00 100.00
Influent_Phosphate
90.00 % Phosphate Removal
Effluent_Phosphate
25.00
80.00
70.00
20.00
% Phosphate Removal 60.00
15.00 50.00
40.00
10.00
30.00
20.00
5.00
10.00
- -
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (Weeks)
Influent and Effluent Phosphate % Phosphate Removal
14

15. E-coli
• The average Influent e-coli level was 2077.2 cfu/100ml.
• The effluent e-coli was reduced from about 1980
cfu/100ml to 7.0 cfu/100ml after 24 weeks of operation
• The average percent removal of coliforms was 99.66%
was achieved.
Influent_Effluent e_coli (cfu/100ml)
% e-coli Removal
3,000.00
120.00
Influent_e_coli
2,500.00
Effluent_e-coli
100.00
2,000.00
e-coli level (cfu/100ml)
80.00
% e-coli Removal
1,500.00
60.00
% e-coli Removal
1,000.00 40.00
500.00 20.00
-
-
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (Weeks) Time (Weeks)
Influent vs Effluent E-coli % E-coli Removal
15

16. Summary of Results
Parameter Average Final %
Influent Effluent Removal
Level Level
Colour (pcu) 209 0 100.00
Turbidity (HTU) 95 6.7 92.96
TDS (mg/l) 616 74 88.00
BOD5 (mg/l) 513 83 83.84
Nitrate (mg/l) 10.91 2.33 78.64
Phosphate (mg/l) 21.75 2.60 88.05
E-coli (cfu/100ml) 2077.2 7.0 99.66
16

17. Energy Requirements and Cost Savings
Water Conventional %
Items Hyacinth Sewage Saving
System Treatment
Energy 45 KWh 340 KWh 87
Requirement
Cost/hr N315.00 N2,380.00 87
Cost/day (20 hrs) N6,300.00 N47,600.00 87
Cost/mth (30days) N189,000.00 N1,428,000.00 87
Cost/yr (12 mths) N2,268,000.00 N17,136,000.00 87
Treatment Capacity = 680m3/day
17

18. Samples along Treatment Process
18

19. From Influent to Effluent
The Difference is Clear!
19

20. THANK YOU
20