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Alternative Sewage Treatment Option: The Effect of use of Water Hyacinth

(Eichornia crassipes) in the Treatment of Domestic Sewage

A. E. AdeniranWorks & Physical Planning Department

University of Lagos, Nigeriaaadeniran@unilag.edu.ng

engrea@yahoo.com

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• 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

Introduction

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The result is polluted canals and water streams

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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.

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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

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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.

bed 1 bed 2bed 3

bed 5 bed 6

Exis

ting

dra

in

drai

n

drai

n

drai

n

circ

ulat

ion

are

a

Existing drain

circ

ulat

ion

are

a

200m

mse

wer

line

WATER HYACINTH BASED SEWAGE PONDS LAYOUT

bed 4

(Influent Point)

Effluent Point

300 300

7000 150

samplepoint A

samplepoint B

samplepoint C

samplepoint D

samplepoint E

1720

300

7100

630

7100

300

300

1850

8500150

8500300 300

flow channel water hyacinth based sewage ponds flow channelinfluent point

effluentpoint

21300 mm 24000 mm 25500 mm 25500 mm

LONGITUDINAL PROFILE FROM POINT A THROUGH E

A B C D E

Screen (steel gauze)BED 1 BED 2 BED 3 BED 4 BED 5 BED 6

water hyacinth based sewage ponds

InceptionChamber

water hyacinthplant

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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..

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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.

Methods

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Water Hyacinth Growth Profile• The growth profile of the water

hyacinth on the sewage ponds is plotted against time.

• It is observed that the growth profile follows an exponential profile.

• The plant growth slowly in the first few weeks and then grow exponentially until the 11th week when the whole pond was covered with the plant

• It was observed that the growth pattern increased from Bed 1 to Bed 6 just as the quality of the sewage improved

Total Area Covered

-

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

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)

Tota

l Are

a C

over

ed (S

q.m

.)

Total Area Covered

Water Hyacinth Growth in Each Bed

-

10.00

20.00

30.00

40.00

50.00

60.00

70.00

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)

Are

a C

over

ed (s

q.m

.)

Bed1

Bed2

Bed3

Bed4

Bed5

Bed6

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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 and Effluent Colour % Colour Removal

Influent_Effluent Colour

-

50.00

100.00

150.00

200.00

250.00

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)

Col

our (

pcu)

Influent Colour

Effluent Colour

% Colour Removal

-

20.00

40.00

60.00

80.00

100.00

120.00

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)

% R

emov

al

% Colour Removal

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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

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

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 (Week)

Turb

idity

(HTU

)

Influent Turbidity

Effluent Turbidity

Influent and Effluent Turbidity % Turbidity Removal

-

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

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)

% T

urbi

dity

Rem

oval

% Turbidy Removal

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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.

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

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

Time (Days)

BO

D (m

g/l)

Influent

Effluent

Influent Vs Effluent BOD

% BOD Removal

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

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 25 26 27 28

Time (Days)

% B

OD

Rem

oval

% BOD Removal

% TDS Removal

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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

Influent and Effluent Nitrate % Nitrate Removal

Tnfluent_Effluent Nitrate

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2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

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 (Week)

Nitr

ate

(mg/

l)

Influent_Nitrate

Effluent_Nitrate

% Nitrate

-80.00

-60.00

-40.00

-20.00

-

20.00

40.00

60.00

80.00

100.00

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 (Week)

% N

itrat

e R

emov

al% Nitrate

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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

Influent and Effluent Phosphate % Phosphate Removal

Influen_Effluent Phosphate

-

5.00

10.00

15.00

20.00

25.00

30.00

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

Influent_Phosphate

Effluent_Phosphate

% Phosphate Removal

-

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

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)

% P

hosp

hate

Rem

oval

% Phosphate Removal

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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 vs Effluent E-coli % E-coli Removal

Influent_Effluent e_coli (cfu/100ml)

-

500.00

1,000.00

1,500.00

2,000.00

2,500.00

3,000.00

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)

e-co

li le

vel (

cfu/

100m

l)

Influent_e_coli

Effluent_e-coli

% e-coli Removal

-

20.00

40.00

60.00

80.00

100.00

120.00

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)

% e

-col

i Rem

oval

% e-coli Removal

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Summary of ResultsParameter Average

Influent Level

Final Effluent

Level

% Removal

Colour (pcu) 209 0 100.00Turbidity (HTU) 95 6.7 92.96TDS (mg/l) 616 74 88.00BOD5 (mg/l) 513 83 83.84Nitrate (mg/l) 10.91 2.33 78.64Phosphate (mg/l) 21.75 2.60 88.05E-coli (cfu/100ml) 2077.2 7.0 99.66

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Energy Requirements and Cost Savings

ItemsWater

Hyacinth System

ConventionalSewage

Treatment

% Saving

Energy Requirement

45 KWh 340 KWh 87

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

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Samples along Treatment Process

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From Influent to Effluent The Difference is Clear!

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THANK YOU