The Design, Construction, and Performance: Cyperus Papyrus Planted Constructed Wetland for Domestic Sewage Treatment in a Medium Size Community in Nigeria Adelere Ezekiel Adeniran, Ph.D., FNSE University of Lagos, Nigeria engradeniran@unilag.edu.ng engrea@yahoo.com 1
Presentation Approach Background/Motivation for the work The Design of the Subsurface Flow Constructed Wetland Construction of the Constructed Wetland Performance Monitoring Re-Use Summary 2
Background The University of Lagos was established in 1962 and it is one of Nigeria and Africa foremost Universities. The University of Lagos, Nigeria operates two systems of liquid wastes disposal. Through the sewer pipes connected to a water hyacinth-based surface flow constructed wetland and individual septic tanks systems for older buildings. The University is gradually replacing the septic tank systems The Kosoko Drive Residential Area is the Community considered for this presentation 3
Location of the Study Area 4
STUDY AREA KOSOKO DRIVE RESIDENTIAL AREA UNIVERSITY OF LAGOS 5
Information on the Study Area Lagos, the biggest and most important city in Nigeria with a population of over 10 million Located on 06 o 25 N 03 o 27 E on the West African Coast. Average Temperature 32 o C Mean Annual Rainfall 1532mm Wastewater generated in the Kosoko Drive Residential Area of the University is about 5m3/day 6
The water table of the University is low, therefore, the Septic Tank System with soak away pits pollute the ground water. The rate of evacuation of the Septic tank is high with the attendant operational costs. Experience with Constructed Wetland on the campus has shown that it is cheaper to maintain and operate. The success of the Water Hyacinth based surface flow CW has motivated research into the use of other wetland plants for domestic sewage treatment Cyperus papyrus is a plant that grows extensively in the University waterfront. Motivation 7
Cyperus Papyrus Cyperus Papyrus Plant Cyperus Papyrus at Unilag Water Front 8
Design Concept 9
Kosoko Drive Residential Area 10
Design Parameters Parameters Actual Designed Population 120 150 Water Supply 6,450 litres/day (From Bulk Meter) 7,000 litres/day Assumed Wastewater generated (70%) 4,500 litres/day 5,000 litres/day BOD 5 Loading Rate (From Existing Facilities) Nigerian FEPA BOD 5 Effluent Limit 420mg/l 30mg/l 450mg/l 25mg/l 11
Sub-Surface Flow CW Area Models The model used to calculate the area of the CW in this work was proposed by: Vymazal et.al, 1998 A = Q d (lnc i lnc o ) / K BOD where A = area Q d = ave flow (m3/day) C i = influent BOD (mg/l) Co = effluent BOD (mg/l) K BOD = 0.08 for Mean Temp 32 o C 12
Design Configurations Area of Wetland required is 180 m2 Aspect Ratio of 4:1 was adopted based on Hydraulic consideration. Five Cells (3m x 12m) connected in series was used. Depth of 0.6m was used (sub-surface flow system) Washed ocean gravel of sizes 4mm, 3mm and 1mm are used as filtration media 13
Schematic Layout of CW Planted with Cyperus Papyrus 14
The Cyperus Papyrus Planted CW Details The CW system has five (5) cells connected in series. Each of has dimension 3m x 12m x 0.60m and planted with cyperus papyrus About 5m 3 /day, domestic sewage from Kosoko Drive residential area, flow through a primary treatment screen before flowing into a Septic Tank The Effluent from the Septic Tank is then allowed to flow into the planted CW. The sewage effluent is then passed through a slow sand filter system for re-use 15
Construction 16
Construction Cont d 17
Construction Cont d 18
Features of the CW system 19
Monitoring Samples of the sewage influent and effluent were collected at each cell for one year on fortnight basis The samples were analysed in the laboratory Level of concentration of the observed parameters were determined at inlet and outlet of each of the wetland cells. 20
Parameters Being Investigated BOD 5 (20 o C) ph Dissolved Oxygen Conductivity Sulphate Nitrate Nitrogen Turbidity Total Dissolved Solids Colour Manganese Iron Total Coliform 21
12 Months BOD Observations 22
BOD Profile over Time at Each Sampling Point 500 450 BOD Level of Sampling Points (mg/l) 400 350 300 250 200 150 100 A0 A B C D E SSF_OUT 50-2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 Observation Time 23
24
ph ph Provile over Time Average ph for Each Sampling Point Observation Time (Week) 7.80 7.60 7.40 7.20 7.00 6.80 6.60 6.40 6.20 6.00 5.80 5.60 2 6 10 14 18 22 26 34 38 42 46 50 SP1 SP2 SP3 SP4 SP5 SP6 SP7 ph Level 7.40 7.30 7.20 7.10 7.00 6.90 6.80 Average ph SP1 SP2 SP3 SP4 SP5 SP6 SP7 30 ph Level Sampling Points 25
Nitrate (NO3_N) NO3_N Profile at each Sampling Point Over Time Nitrate Level (mg/l) 18.00 16.00 14.00 12.00 10.00 8.00 6.00 4.00 2.00 - SP1 SP2 SP3 SP4 SP5 SP6 SP7 2 6 10 14 18 22 26 30 34 38 42 46 50 Time (Week) 26
Summary of Observations 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 27
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 28
Samples Along the CW Longitudinal Profile (After One Year of Operation) 29
Benefits From the Project Item Before After Ground Water Pollution e-coli 980 mg/l 15mg/l Operational Cost/Year $1,250/year $436/year Cost of Construction $0.0 $5,000.00 Sale of Catfish $0.0 $5,960/month Extra Money Available for R & D $0.0 $5,000/month Available Water for Re-Use 0.0 litres/day 5,520 litres/day Environment Ambient Fouled Clean Opportunities for other Research Nil High 30
Re-Use 31
Monthly Catfish Harvest 32
Conclusions Cyperus Papyrus plant is effective as constructed wetland plant in the treatment of domestic sewage under tropical conditions CW is a cheaper alternative to conventional waste treatment plants (especially in the poor nations of the developing countries) CW technology is simple, appropriate and sustainable for the low income communities. The economy and welfare of the community can be enhanced through re-use 33
THANK YOU 34