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North-South Centre Colloquium - ETH
UNIVERSITY OF YAOUNDE I
Effect of salinity on the nutritive value of
E. pyramidalis (Lam.) Hitchc & Chase forage plant
fed with faecal sludge supernatant
Marie-Madeleine NGOUTANE PARE
Ph.D Student
Supervisors:
Pr. Amougou Akoa
University of Yaoundé I - Cameroon
Dr. Doulaye Koné
Eawag/Sandec - Switzerland
14th May 2009
Eawag: Das Wasserforschungs-Institut des ETH-Bereichs

Outline
1. Introduction
Background of the study
Research hypothesis
Aims of the study
2. Materials and methods
3. Results and discussion
4. Conclusion
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Background of the study
Influence of climate change on the natural
resources :
1. Rapid growth rate of urban population;
2. Increasing food demand.
Food security is an important issue.
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Background of the study
• Many resources are wasted in cities
• Failure in water and sanitation provision
• Malfunctioning of wastewater treatment
systems in Africa and Asia :
Lack of financial and human resources for
operation and maintenance (Koné, 2002).
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Background of the study
Introduction
• Link sanitation infrastructure and cities
economic development
Encourage reuse of nutrients and water;
Couple agricultural system and sanitation
technology
=> CLOSE THE LOOP
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Background of the study
Introduction
Constructed wetland (CW)
=> Biomass productions
=> Valuable opportunities:
• Producing safe forage;
• Recycling wastewater;
• Providing long-term sustainable source of income
for covering treatment plant Operation &
Maintenance cost
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Background of the study
Introduction
Echinochloa pyramidalis (Lam.) Hitchc & Chase (Poaceae)
Grows in humid environment
Forage plant
Originates from tropical Africa
Widely distributed in tropical regions
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Background of the study
Introduction
Echinochloa pyramidalis (Lam.) Hitchc & Chase (Poaceae)
• High potential to treat wastewater and human excreta;
• High yielding potential in CW (Kengne et al. 2008)
⇒ New perspectives for producing forage from
wastewater and faecal sludge treatment (Koné, 2007).
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Background of the study
Introduction
• Demand for livestock products increases of 3 % per
year in sub-Saharan African
• Forage availability for urban and peri-urban dairy
system is steadily decreasing (Rischkowsky et al., 2006)
⇒ Acute shortage of forage (seasonal fluctuation)
⇒ Low quality of forage
• Spread of dairy enterprises in the urban centers
=> the demand of forage plant has been increasing
• Both dry and fresh E. pyramidalis are marketed
=> opportunity to generate incomes for operational and
maintenance of sanitation infrastructure
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Background of the study
Introduction
Question:
Does E. pyramidalis tolerate the salinity of
faecal sludge ?
• In Cameroon: wide variations in the composition of
faecal sludge with high salt contents.
• Similar concentrations to those of other sub-Saharan
countries like Burkina-Faso, Ghana (Koné et al., 2004).
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• The conductivity of faecal sludge from the Yaoundé
urban areas varied from 0.7 to 15 mS/cm.

Research hypothesis
Introduction
High salt content of faecal sludge has an
effect on E. pyramidalis, in particular:
Its nutrient content
Its cell-wall composition
Mineral composition
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Goal of the study
Introduction
Evaluate the effect of salt stress on the nutritive
value of E. pyramidalis
Parameters under study:
Crude protein content;
Cell-wall composition : NDF, ADL, ADF
Mineral composition :
Na + , Ca 2+ , Mg 2+ , K + , Cl - and SO
2-
4
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Location of the study sites
Yaoundé
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Materials & Methods
Experimental unit for salinity trials
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Materials & Methods
Experimental design:
24 small-scale units of VFCW with a capacity of 50 L
and a section of 0.78 m 2 ;
randomly divided flooded and non-flooded conditions.
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Materials & Methods
Planting
Young shoots collected in the natural wetlands,
with 20 cm of length
Were planted at a density of seven plants per
bed.
Acclimatization
Beds were flooded with raw wastewater
(EC< 2000 µS/cm) to about 5 cm above the
gravel layer, for 8 weeks.
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Materials & Methods
Salinity experiment – Feeding of experimental units
• Twice a week with 15 L of faecal sludge (FS) supernatant
• Four different salinity level:
(EC = 2000, 3000, 6000, 9000 µS/cm)
And a control (< 2000µS/cm).
Salinity level = Salinity in Faecal sludge supernatant + KCl +
Ca(NO 3 ) 2 + Na 2 SO 4
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=> Salts added to obtain the desired electrical
conductivity

Materials & Methods
Characteristics of applied faecal sludge
supernatant :
• Redox potential (9.4 to 27.6 mV)
• Salts: anions (NO 3- , Cl - , SO 4
2-
) and
cations (Na + , Ca 2+ , Mg 2+ , K + )
• Total nitrogen
• pH neutral
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Materials & Methods
• Plant sampling
Harvest at two different periods (45 and 100 days)
Plants were cut at 20 cm above the sand level and
divided into leaves and stems.
• Plant Analysis
Water content
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Materials & Methods
Chemical analyses
Total N determined by Kjeldahl procedure (AOAC, 2000);
Crude Protein (CP) calculated as N×6.25;
Acid Detergent Fiber (ADF) (AOAC, 2000);
Neutral Detergent Fiber (NDF) and sulfuric Acid
Detergent Lignins (ADL) ( Van Soest et al., 1991)
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Materials & Methods
Mineral analyses
Flame photometer
for Na + , Ca 2+ , Mg 2+ , K +
Spectrophotometer
for Chloride (Cl-).
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Results and discussion
Effect of salinity on the water content of the forage stems
Treatment period
= 45 days
Treatment period
= 100 days

Results and discussion
Effect of salinity on the water content of the forage leaves
Treatment period
= 45 days

Results and discussion
45 and 100 days treatment:
• Increase of salinity => Decrease of water content in
leaves and stems
• Plant water content in flooded condition

Results and discussion
Crude Protein (CP):
• In leaves => 11-18 % DM
• In stems => 7-16 % DM
• CP decreases as salinity increases
• Significant reduction at 6000 and 9000 µS/cm
• No difference between flooded and free drainage
conditions
• No difference between 45 and 100 days of salt
treatment
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=> Values in the stems and leaves are above the
minimum requirement (6-8 % DM) for livestock
productions and proper ruminant-bacteria functioning

Results and discussion
Cell-wall content (ADF, ADL (sa), NDF)
• 45 and 100 days treatment
LEAVES:
ADF varied from 27- 38 % DM
ADL from 8-14 % DM
NDF from 58- 75 % DM
Values in the control are higher
STEMS:
Values higher than in the leaves.
• No significant difference between the control and
other treatments for ADF, ADL (sa)
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• Significant difference between the control and
other treatments

Results and discussion
Mineral composition
• No difference between 45 and 100 days
• No difference between flooded and free drainage conditions
• Range within these concentrations (g / 100g DW):
Mg 2+ : 0.17 - 0.21
K + : 0.5 – 1.0
Na + : 0.01 – 0.25
Ca 2+ : 0.17 – 1.53
=> Meet the requirements for animal nutrition
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Conclusion
Quality of cell-wall constituents of E. pyramidalis
were improved in the salt affected vertical-flow
constructed wetlands;
Leaves are richer in nutrients than stems
Salt stress did not have any impact on mineral
uptake;
=> Salt stress did not lead to mineral deficiencies.
Crude protein value of the plants was higher in
the constructed wetland than in Nature
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Conclusion
Rapid growth rate
High biomass production
High protein content
Ability to maintain the nutritive potential under saline
conditions
=> E. pyramidalis is appropriate for constructed
wetlands treatment
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=> Constructed wetlands can be adapted to
producing high nutritive forage plant !

Conclusion
Further investigations are needed:
• Evaluation of forage intake and digestibility
• Hygienic quality and safety
• Plant management, harvest times
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Acknowledgemements
• Swiss Federal Institute of Aquatic Sciences and
Technology (Eawag), Department of Water and
Sanitation in Developing Countries (Sandec),
• Commission for Research Partnerships with
Developing Countries (KFPE)
• International Foundation for Science for their financial
and logistical support (IFS, Sweden grant N° W/4262-
1)
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THANK YOU FOR YOUR ATTENTION !
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Further information:
marie-madeleine.ngoutane@eawag.ch