沙漠研究 22-1, 315 -318 (2012 )"ICAL 1 / DT X"

Journal of Arid Land Studies－Refereed Paper－Soil Amendment by Sediment from Water Storage Reservoir as a Restoration
Technique in Secondary Treated Wastewater Irrigated Area at El Hajeb Region(Sfax-Tunisia)
Slim MTIBAA1), Mitsuteru IRIE2), Olfa HENTATI1), Habib TRABELSI3), Monem KALLEL1),
Mohamed KSIBI*1) and Hiroko ISODA2)
Abstract: The negative impacts of irrigation with treated wastewater (TWW) effluents on soils and groundwater aquifer in thevicinity of Sidi Abid Region (Tunisia) is well established. In order to assess the feasibility of sediment utilisation as soil amendment,
sediment was extracted from the bed of water storage reservoir, dried and mixed with a soil from the study area at the rate of (35 t/ha).
The effects on the soil properties, yield and nutrient contents of Wild OAT (Bromus ramosus) were studied. As the most relevantchanges, sediment improved the soil water-retention and cation exchange capacity of the mixture, but increased its salinity and heavy
metal contents. Yield of OAT increased in parallel with the sediment application whereas OAT growth and yield remained unaffectedin the control. Significant effects were also found on the nutrient contents of the plant tissues but no heavy metal accumulation inplants could be detected. According to the results, the application of appropriate rate of sediment to the agricultural soil in El Hajeb
seems to be a sound practice to avoid problems of salinity and alkalinity, and to improve the properties of the sandy soils of the area.
Key Words: Effluent from wastewater treatment plant, Salinity, Sediment, Soil amelioration.
stage and cropping term.

1. Introduction
2. Materials and Methods
The reuse of treated municipal wastewater is part of theengagement strategy and development of water resources inTunisia. Consequently, the excessive discharge of the groundwater with low quality has occurred, which has imposed afurther increase in soil salinization. On the other hand thereduction of water storage capacity of reservoirs in Tunisia
because of the accumulation of sediment was reported by Irieet al. (2011). He demonstrates that the storage capacity wasreduced by 6% from 2000 to 2009. The potential applicationof sediment as amendment in order to increase soil and crop
quality parameters, which are significantly affected bylong-term wastewater irrigation, was studied. In this work,
the soil from in the vicinity of Sidi Abid Region (south ofTunisia) named El Hajeb irrigated by TWW effluents since
1989, was ameliorated by sediment extracted fromJoumine reservoir located on the north area of Tunisia, (50 kmfrom Tunis). The production test of Wild OAT (Bromusramosus) will be carried out on two experimental plots (2m × 2m each), control and ameliorated with sediment. The
production test has been started since October 12, 2010. The
effect of soil amelioration by sediment was evaluated withbiomass of the products and soil characteristics at growing

2.1. Study site and experimental design
Two cropland sites of four square meters each one, one
amended with sediment at the rate of 35 tons of sediment per
hectare (normal amount in case of leaf mould fertilization) andthe other without sediment using as control, were studied at El
Hajeb area (Fig. 1), which is located at longitude 10°38'8.34"E,
latitude 34°40'47.52"N, 10 km west from Sfax. This site ischaracterized by arid climate make irrigation essential for crop
production (Belaid et al., 2010). The sediment was air dried,
grinded and mixed with the surface soil of 15 cm from the top.
Then, the plots were seeded with Wild oats (Bromus ramosus)
and irrigated with 15L/m2 every 15 days by TWW effluents.
2.2. Soil Sampling / Soil and sediment analysis
From the top soil of each plot, three samples were taken
every month, since October 2010. The samples wereair-dried in the laboratory and passed through a 2 mm aperturesieve, then analyzed for chemical and physical properties. pH,electrical conductivity (EC), water holding capacity (WHC),
organic matter and moisture content were determined bystandard methods. Exchangeable cations were measured by* Corresponding Author: mohamed.ksibi@tunet.tn
Route de Soukra Km 3,5 Po. Box 1173, 3038 Sfax, Tunisia
1) University of Sfax, Laboratory of Water, Energy and Environment, National School of Engineering of Sfax (ENIS)
2) Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan.

3) Périmètre irrigué d'El Hajeb route Matar km 9, 3078 Sfax, Tunisia.

Table 1. Physic-chemical characteristics of sediment.
CharacteristicValue

2.4. Reproduction test with springtails Folsomia candida
and Oligochaeta Enchytaeus albidus
Reproduction test with F. candida was performed
according to the OECD 232 (2009) guideline. Each replicate
consisted of a glass container filled with 30 g (dry weight) of
natural soil amended with different percentages of sediment(10%, 20%, 30%, and 40%), in which 10 synchronizedjuvenile springtails (10-12 days old) were introduced. Again,control treatment was made with natural soil only. The
number of surviving adults and juvenile were determined after
28 days.
Reproduction test with E. albidus was performed according
to the OECD 220 guideline (2004). Test procedure is similar
to springtails test. Statistical analysis was performed with the370
63.16
67.62

1,60229[Å];Calcite,syn;Corundum,syn

1,91183[Å];Calcite,syn
1,87422[Å];Calcite,syn
1,81536[Å]2,09304[Å];Calcite,syn;Corundum,syn

2,28074[Å];Calcite,syn

2,56786[Å];Corundum,syn
2,49038[Å];Calcite,syn

14.82
6.33
4.8
6.73

3,03223[Å];Calcite,syn

3,34145[Å]3,83768[Å];Calcite,syn

3,56937[Å]200

4,46429[Å]4,24741[Å]7,11493[Å]42,14976[Å]

400

7.37
967
7.17
111

0102030Position [°2Theta]

605040Fig.2. the XRD pattern of Sediment with d space.
20100

Cumulative(％)

2.3. Analyses of growth parameters, biomass and heavy
metals in plants
Five plants were selected randomly from each plot, every
two weeks, to measure the length. 185 days after sowing, thecrop was harvested manually, to preserve each part of grass(root, stoke and leaf, and grain) and stored in polyethylene bagsin the laboratory to analyze. Crop total weight was measured
after washing plants and then air drying in the laboratory, total
fresh weight was expressed as g.m-2. For heavy metal
analysis, oven-dried plant parts samples were homogenized bygrinding in stainless steel blender and then passed through asieve of 2 mm mesh size. Grinded sample of 1g was digested
in 20ml tri acid mixture (HNO3:H2SO4:HClO4:5:1:1) till atransparent colour appeared. Heavy metal concentrations
were determined in the filtrate by using AAS.

Sédiment
600

Countsusing Atomic Absorption Spectrophotometer (ASS) after
extraction with 0.5M barium chloride solution. Soluble
cations were measured using distilled water instead of 0.5M
BaCl2. Heavy metals concentrations were determined byusing ASS after aqua regia acid digestion. The mineralcomposition of sediment was determined by X-ray diffraction(XRD) analysis. Sodium Adsorption Ratio (SAR) wascalculated as:
SARsoil = Na+/ (Ca 2+ + Mg 2+ ) / 2(1)Cation Exchage Capacity (CEC) was calculated as:
CEC (mEq/100 g) = Ca2+ (ppm)/200 + Mg2+ (ppm)/120(2)+ K+(ppm)/390 + [9*(7,5 – pHbuffer)]

15(％)

Fig.1. Map of the study area.

pHEC (µS.Cm-1)
Organic content (% dry weight)
CEC (mEq/100g)
Exchangeable cations (meq.Kg-1)
Ca2+
Mg2+
K+
Na+Soluble cations (meq.Kg-1)
Ca2+
Mg2+
K+
Na+

1050

5010 -1

10 0

10 1

Particle size(μm)

10 20Fig.3. Particle size cumulative curve.

SPSS software package (version 19.0.0). One-way Analysisof Variance (ANOVA) and least significant difference (LSD)
test were performed to compare the reproduction levels of soil
animals between control soil and amended soils (10% to 40%).

3. Results and Discussion
3.1. Sediment characteristics
3.1.1. Physic-chemical characteristics of sediment
Table 1 shows the physic-chemical properties of thesediment. The pH was neutral equal to 7.37, the EC was very
high which is due to the presence of high amount of salts andcations. The sediment is characterized by a high CEC equal
to 111 mEq/100g due to clay content and organic matter. The
high CEC allows plants to resist against stress. Sediment isvery rich in calcium as shown by exchangeable cations. The
high level in calcium indicate the presence of carbonate as
calcite as confirmed by the XRD analysis (Fig. 2).
Figure 3 shows the particle distribution of the sediment.
The median particle size of sediment is 5 µm which indicatesthat the sediment in Joumine reservoir is quite fine clay andmoderate organic contents (Irie et al., 2011).

Table 2. Heavy metals concentration in the sediment
Heavy metals
Value in sediment (mg.Kg-1)
NFU 44-051(mg.Kg-1 DM)
Cu
14.75 ± 0.25
300
Pb
28.5 ± 0.75
180Ni25.5 ± 1.75
60
Zn
95.75 ± 2.75
600
Fe19991 ± 435
Cd1.5 ± 0.25
3Co
44 ± 1.25
Mn
270 ± 13-Fig. 5. Evolution of the EC in control soil (grey line) and in soil
amended by sediment (dark line).

A***** **B**

* *

* *

Fig. 4. Reproduction tests with F. candida (A) and E. albidus (B).
Number of adults in soils (black bars). Number of juveniles
produced in soils (white bars). Values are means +SD. ‘‘*” indicatessignificant statistical differences (P < 0.05) from control soil.

3.1.2. Heavy metals in the sediment
In sediment, mean metal level (Cu, Pb, Ni …) weregenerally higher. This could be as a result of adsorption tosediment particles. Some of these elements are essentials forthe growth of plants whereas others are not essentials. Thevalues of the metals content quantified in the sediment (Table 2)
are in conformance with a statutory norm (e.g. norm NF
44-051 on organic fertilisers). Thus the sediment can be used
as a soil amendment to add organic matter to disturbed soils.
3.1.3. Risk characterization of sediment
In the two reproduction tests (Figs. 4 A and B), the numbersof springtails and earthworms juveniles, decrease with theincreasing percentages of sediment. This is due to the chronic
effect of heavy metals present in the sediment, affecting thereproduction function of animals. In fact, at 40%, neither
springtails nor earthworms juveniles were counted. It is
worthy to note, that at this concentration the sediment changed
the structure of amended soil due to its high content in clay.
Consequently, the soil becomes an unfavourable environment for
housing these invertebrates. A significant higher decrease of
number of springtails and of earthworms (adults and juveniles)
after 28 days was found on both amended soils (10- 40%).
3.2. Effects of sediment on soil characteristics
3.2.1. Evolution of soil electrical conductivity
Soil salinity, measured as EC in both control soil and soilFig. 6. Evolution of pH in control soil (grey line) and in soil amended
by sediment (dark line).

amended with sediment show significant increasing ofelectrical conductivity with time after irrigation with TWW.
This could be attribute control soil extract in used to theoriginal high level of total dissolute salt of the wastewater. At
the same time the effect of evaporation, salt in the soil was
moved to the surface and raise soil EC. However, the EC riseof soil amended by sediment is higher than that of control. It
seems that soluble cations in the sediment perform the functionof soil amelioration.
3.2.2. Evolution of soil pH
The effect of TWW irrigation on soil pH is not constency.
It has been reported by Schipper et al. (1996) that soil pH
increased following long term TWW irrigation and they
attributed this increase to the chemistry and high content ofbasic cations such as Na+, Ca2+ and Mg2+. Regarding theobtained results in term of the variation of pH versus time insoil amended with sediment and control soil, on the last day ofour experiment, the pH of amended soil is equal to 7.6
however, it is about 7.8 for control soil. Also, the SAR ofamended soil (0.7) is smaller than that of control soil (0.8). It
seems then that the sodium ratio in control soil is greater thanthat in amended soil. Alkalinity soil is due to the presence ofsalt (carbonates of calcium, magnesium and sodium)comparatively in high degree. This problem is corrected byusing sediment as shown in Figure 6. The soil amended withsediment is less alkaline than the control soil. Consequently
the sediment contributes to the neutralisation of the alkalinity
caused by irrigation with TWW.
3.2.3. Evolution of soluble Calcium concentration
Except the result of Feb, 16 and Mar, 15, sediment reduces
the soluble Ca2+. Perhaps it's due to the change of physicalstructure of soil. Sediment is originally clay, finer thanoriginal soil of El Hajeb. It’s diversifying the particle
distribution and aggregation. So, sediment improves the airand water permeability. As a result, soluble Ca2+ was washedFig. 7. Evolution of soluble Calcium: in soil amended by sediment(darck bars) and in control soil (white bars).

the site amended by sediment. However, the report about
weight of grain and total weight is about 28% in the siteamended by sediment and 26% in the control site.
3.3.3. Accumulation of heavy metals in plants
The application of soil amendments favours plant growth.
Sediment amendment application led to an effective
immobilization of Pb, Cu, Zn and Cd phytoaccessible forms insoil. It led to decrease heavy metal content in Wild OAT parts.
However the accumulation of heavy metals is well observed inroots of plants growing in soil amended by sediment. Thislatter is especially effective for reduction of the Cu, Zn and Mncontents in Wild Oat parts. The sediment amendments are ofgreat interest for the purpose of phytostabilization.

Fig. 8. Evolution of grass height in control soil (grey line) and soil
amended with sediment (dark line).

4. Conclusion

AB

Fig. 9. A: Crop weight in control soil (white bars) and in soil amendedby sediment (dark weight). B: Report between weight of grain
and total weight in control soil and in soil amended by sediment.
Table 3. Heavy metals value in plants seeded in the soil amended bysediment (Soil1) and control soil (soil2). Values were in mg/Kg
metalsValue in roots

Value in shoots

Value in grain

Soil1

Soil2

Soil1

Soil2

Soil1

Soil2

Cu

11.3

13

3.52

3.512

5.046

8.122

Pb

5.264

1.84

ND

ND

ND

ND

Ni

6.1

3.71

ND

ND

ND

ND

Zn

89.03

49.34243.07232.224

37.8

49.17

Fe

2198

2115.64

40.528

44.25

37.2

25.4

Cd0.428

0.342

ND

0.272

ND

ND

Co

1.448

2.652

ND

1.26

ND

ND

Mn

41.6

66

14.456

39.49

6.46

9.078

Amendment with sediment extracted from the bed of water
storage reservoir enriches the soil with organic matter as wellas improves its structure and physical properties. The resultsof this experimental study show that organic acids (presumably
humic or fulvic acids) can dissolve from the sediment anddestroy soil alkalinity (pH=8.2).
Soluble calcium issignificantly increased by about 20 mequiv.kg-1 of soil.
Ecotoxicological tests included earthworm (Enchytaeusalbidus), 28 days survival show that the sediment at higher
percentage has negative effects on the soil individuals because
it is very clayey, thus the soil becomes an unfavorable
environment for housing for individuals. Heavy metals
concentrations in sediment are acceptable and no accumulation
has been observed in the different parts of crop. Significant
differences were observed in heavy metal concentrations in theplants seeded in the soil amended with sediment compeered tothe control soil. Heavy metal content in soil and plant tissuesof Wild OAT decreased significantly compared with those
without sediment which play role of chelating agents.

Acknowledgement
This research was partially supported by the JST/JICA,
SATREPS project.
Referencesby the irrigated water and the accumulation of soluble cations
on surface was reduced by evaporation. Discussion on sediment(cations of pure sediment) characteristics is high content of
exchangeable Ca2+ in comparison with El Hajeb soil (sandy).
3.3. Effects of sediment on biomass parameters3.3.1. Evolution of grass height
In the presence of sediment as soil amendment the growthof Wild OAT (Bromus ramosus) is better than for control soil.
It seems that the humic substances in the sediment perform thefunction of soil amelioration.
3.3.2. Crop weight
Total weight of biomass is higher in the control site than in

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Irie M., Kawachi A., Tarhouni J., Gharbi A. (2011):
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(1996): Impact of land-applied tertiary-treated effluent on
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