1 1 1
Constructed Wetland Wastewater Treatment and Effluent Reuse as Source of Additional Raw Water: The Experience
of University of Lagos, Nigeria
Adelere Ezekiel Adeniran, Ph.D., FNSE University of Lagos, Nigeria
2 2
Location of the Study Area
3 3
Information on the Study Area • Lagos, the biggest and most important city in Nigeria
with a population of over 10 million • Located on 06o25’N 03o27’E on the West African
Coast. • Average Temperature 32oC • Mean Annual Rainfall 1532mm
4 4
Motivation • There exist a gap in the demand and supply of water
supply to the University of Lagos, Nigeria (Unilag). • The inefficiency and incapability of the Municipal
Water Supply Authority. • The University, therefore, acts as its own Municipality. • Need to reduce the University’s water stress situation
to cope with domestic and research needs
5
Unilag Water Supply and Demand 1991 - 2010
Unilag Water Demand Vs Supply
-
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
3,500,000
19911992
19931994
19951996
19971998
19992000
20012002
20032004
20052006
20072008
20092010
Years (1991 - 2010)
Quan
tity (c
u.m.)
Water DemandWater Supply
6 6
Clean Technology • Clean technology (clean tech) is a general term
used to describe products, processes or services that reduce waste and require as few non-renewable resources as possible.
• Constructed wetlands (a form of clean tech) are
engineered waste water treatment systems and are being successfully used for environmental pollution control.
7 7
Arial View of Unilag CW System
8
Schematics University of Lagos Constructed Wetland System
9 9 9
• Samples of the sewage influent and effluent were collected at each cell from 2010 to 2012 on a weekly basis
• Level of concentration of the
observed parameters were determined in the laboratory for the inlet and outlet quality parameter of each of the wetland cells.
Quality Monitoring
10 10
12 Months BOD Observations
11 11
Observations Means 2010 - 2013 Parameters Units Influent Effluent % removal
pH 7.13 7.1 0.42
TDS Mg/l 469 46 90.19
Turbidity HTU 108.75 1.98 98.18
Colour PCU 428 8 98.13
Conductivity μΩ/cm 1 0.26 74.00
Dissolved Oxygen mg/l 3.14 7.49 (138.54)
Iron mg/l 1.13 0.28 75.22
Sulphate mg/l 58.5 35 40.17
Nitrate mg/l 13.79 1.77 87.16
Manganese mg/l 60 0.61 98.98
BOD mg/l 432.99 24.47 94.35
Total coliforms Cfu/100ml 900 23.44 97.40
12 12
Comparison with FEPA Standards Parameter Units Effluent Quality FEPA Standard for
Discharge into Streams and
Wetlands
PH 7.1 6.0-8.0
TDS mg/l 46 2000
Turbidity HTU 1.98 <10
Colour ( PCU 8 25
Conductivity μΩ/cm 0.26 1.5
Dissolved oxygen Mg/l 7.49 4.5
Iron(Fe) Mg/l 0.28 10
Sulphate Mg/l 39 500
Nitrate Mg/l 2 10
Manganese(Mn) Mg/l 24.47 20
Coliform MPN/100ml 23.44 400MPN/100ml
BOD Mg/l 12.8 30
13 13
From Raw Sewage to Drinkable Water
• Effluent from the Constructed wetland good enough to be used as raw water
• Even drinkable and potable at source.
14 14
Field and Board Room Decisions: Benchmark Quality and Determine
Quantity of Effluent Reuse?
15
Comparison of CW Effluent Quality with Existing Raw Water Quality
pH
0
1
2
3
4
5
6
7
8
9
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
pH V
alue
PH BHRWPH CWRW
pH Conductivity
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
Cond
uctiv
ity (u
S/m)
COND. BHRW
COND CWRW
Conductivity (µSm-1)
Total Dissolved Solids (TDS)
0
10
20
30
40
50
60
70
80
90
100
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
TDS
(mg/
l)
TDS BHRW
TDS CWRW
TDS (mg/l) Turbidity
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
Turb
idity
(THU
)
TURBIDITY BHRW
TURBIDITY CWRW
Turbidity (FTU)
16
Quality Compare Cont’d Colour
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
Colo
ur (H
U)
COLOUR BHRW
COLOUR CWRW
Iron
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Months
Iron
(mg/
l)
IRON BHRW
IRON CWRW
e_coli
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Jan-12
Feb-12
Mar-12
Apr-12
May-12
Jun-12
Jul-12
Aug-12
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
Feb-13
Mar-13
Apr-13
May-13
Jun-13
Jul-13
Aug-13
Month
e-co
li (c
fu/1
00m
l)
E.COLI BHRWE.COLI CWRW
Colour (HU) Iron (mg/l)
e-coli (cfu/100ml)
17
Effluent Quantity Additions
Year As Raw Water (Cu.m)
Treated Water
2011
544,590
490,113
2012
622,486
560,238
2013
569,951
512,956
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Improving Water Supply Situation
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Conclusions • The water stress in the University has reduced
since 2011 • Reclaimed effluent from properly treated
Constructed wetlands can be a source of additional raw water in water stressed area e.g. Nigeria
• There is need for continuous monitoring to
avoid polluted water from entering the raw water system.
On-Going Works
• Production of Biogas from: – Sludge from the Constructed Wetland – Biomass from the harvested wetland plants
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Further Works • Work on other Waste
Treatment Plants including Connection of Isolated Septic to Sewer lines.
• The current works
captures about 40% of Wastewater generated in the University
22
Acknowledgement
• University of Lagos, Nigeria • My Colleagues
– Mrs. T. A. Aina – Miss O. Oshunrinade – Mr. A. Lateef
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THANK YOU
