American Journal of Plant Sciences, 2013, 4, 1736-1743
http://dx.doi.org/10.4236/ajps.2013.49213 Published Online September 2013 (http://www.scirp.org/journal/ajps)
Effect of Treated Waste Water Irrigation on Plant Growth
and Soil Properties in Gaza Strip, Palestine
Yasser El-Nahhal1,2, Khalil Tubail1, Mohamad Safi1, Jamal Safi1,3*
1Environmental Protection and Research Institute, Gaza, Palestine; 2The Islamic University of Gaza, Gaza, Palestine; 3Al-Azhar
University of Gaza, Gaza, Palestine.
Received June 30th, 2013; revised July 30th, 2013; accepted August 10th, 2013
Copyright © 2013 Yasser El-Nahhal et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
This study investigated the effect of treated wastewater (TWW) irrigation on growth of Chinese cabbage and corn and
on soil properties in Gaza Strip, Palestine. Chinese cabbage and corn were planted in winter and summer seasons re-
spectively in a sandy soil. The experimental design was a randomized complete block using 2 treatments with 4 repli-
cates. Soil samples were collected from 0.0 - 120 cm depths from all plots and analyzed for pH, electric conductivity
(EC) and nutrient contents. The plants were irrigated with either TWW or fresh water (FW) fortified with NPK, while
control used drip irrigation system. The biomass (total fresh weight of the plants) was used as an indicator of the plant
yields. Concentration of heavy metals on plant leaves was determined by Inductive Coupled Plasma Analyzer (ICP) and
was taken as an indicator of plant quality. Biomass of Chinese cabbage and corn grown in plots irrigated with TWW
was higher than those grown in plots irrigated with FW. These results indicate the ability of TWW supplying the neces-
sary nutrients for plant growth. Heavy metal content in plant leaves in all treatments (TWW and FW) was nearly similar
and below EPA standards, indicating high quality of plants. Soil analysis showed great changes in soil properties due to
irrigation with TWW. The interesting outcome of this study is that TWW is an effective source for plant nutrients. It is
encouraging to reuse TWW in agricultural system after full treatment.
Keywords: TWW; FW; Corn; Chinese Cabbage; Heavy Metals
1. Introduction
The quantity of treated wastewater (TWW) in Gaza is
about 111,900 m3/day [1]. This quantity is expected to
increase during the coming years due to population
growth. Guidelines for safe and effective reuse of TWW
for agricultural purposes are not yet approved by the
Palestinian Authority, or any Research Institute. Regard-
less of this fact, this high quantity of TWW should be
reused in the agricultural or industrial sectors to solve the
problem of water quality in Gaza Strip Palestine. Al-
though TWW in Gaza did not meet the international
standards, several trials have been made by international
institutions in Gaza for the reuse of TWW in agriculture.
For instance, effluent from the existing Gaza waste water
treatment plants (WWTP) is currently being used by
farmers through pilot projects funded by the Spanish and
French governments. In the Spanish project the trial in-
cludes irrigation of citrus and olive trees in Gaza area
(Stawi Farm in Al Zeitoon area, 100 dunums), and in the
French project the trial includes irrigation of forage crops
in North area ( beit Lahia, 40 dunums). Obviously, these
trials are not based on scientific research. They used the
TWW without looking into the quality of the products or
the effect of TWW in soil properties.
Nevertheless, elsewhere several investigations have
been made to evaluate the quality of TWW for possible
reuse in agricultural sectors. For instance, Evett et al. [2]
evaluated the feasibility of using TWW irrigation strate-
gies based on 1) water use of different tree species, 2)
weather conditions in different climate zones of Egypt, 3)
soil types and available irrigation systems, and 4) the re-
quirement to avoid deep percolation losses that could
lead to groundwater contamination. They concluded that
drip irrigation systems are preferred to achieve several
small irrigations per day in order to avoid deep percola-
tion losses. Mendoza-Espinosa et al. [3] evaluated the
effect of treated wastewater on the growth of cabernet
sauvignon and merlot grapes from the Guadalupe Valley,
*Corresponding author.

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1737
Mexico. They reported that the number of leaves per
shoot and the overall biomass increased in plants irri-
gated with wastewater and grape production per plant
was 20% higher and the concentration of carbohydrates,
organic acids and pH were similar in grapes from vines
irrigated with wastewater to those irrigated with ground-
water. Oron et al. [4] evaluated the influence of TWW on
sustainable agricultural production and safe groundwater
recharge using filed experiment. They reported that ul-
trafiltration stage is efficient in the removal of the pa-
thogens and suspended organic matter while the succes-
sive Reverse Osmosis (RO) stage provides safe removal
of the dissolved solids (salinity). Best agricultural yields
were obtained when applying effluent had minimal con-
tent of dissolved solids (after the RO stage) as compared
with secondary effluent without any further treatment
and extended storage. Mosse et al. [5] investigated the
effect of application of winery wastewaters to physico-
chemical properties of soils. They concluded that long-
term application of winery wastewaters had significant
impacts on soil respiration, nitrogen cycling and micro-
bial community structure, but the treated wastewater ap-
plication showed no significant differences in wetting
alone. Singh et al. [6] investigated the effect of land ap-
plication of sewage sludge on the physicochemical pro-
perties of soils. They concluded that amending soil with
sewage sludge modified the physicochemical properties
of soils, and might contaminate ground water, stock
ponds, or produce food chain contamination from eating
food grown in sludge-treated land. Castro et al. [7] stud-
ied the effects of wastewater irrigation on turfgrass
growth, and reported that plants irrigated with treated
wastewater had the highest sodium content. Pritchard et
al. [8] investigated the risks of the environment and food
crops that may come from land application of sewage
sludge in Australia. They reported that the attention was
given to researches related to plant nutrient uptake, par-
ticularly nitrogen and phosphorus (including reduced
phosphorus uptake in alum sludge-amended soil); the
risk of heavy metal uptake by plants, specifically cad-
mium, copper and zinc; the risk of pathogen contamina-
tion in soil and grain products; change of soil pH. Bel-
yaeva et al. [9] investigated the effects of adding biosol-
ids to a green waste feedstock (100% green waste, 25%
v/v biosolids or 50% biosolids) on the properties of com-
posted products. They found that addition of biosolids to
the feedstock increased total N, EC, extractable NH(4),
NO(3) and P but lowered pH, macroporosity, water hold-
ing capacity, microbial biomass C and basal respiration
in composts. This paper investigates the effect of TWW
irrigation on Chinese cabbage and corn growth and qual-
ity and on soil properties in Gaza Soil.
2. Materials and Methods
2.1. Environmental Background of the Study
Area
Gaza Strip is a semi-arid region of roughly 365 km2
which lies on the Mediterranean Sea. On this narrow
strip, almost 1.625 million of the Palestinian people live
and work [10]. The ground water is used for irrigation,
industrial and domestic purposes. A “Catastrophic” water
shortage, water pollution with high salinity and micro-
pollutants, lack of sewage and solid waste treatment, ma-
ritime pollution, overcrowding, poverty and uncontrolled
use of pesticides are the most pressing environmental
problems in the Gaza Strip. Internationally suspended,
banned and canceled pesticides which considered muta-
genic and carcinogenic are still used in the agricultural
environment. The wastewater sector in the Gaza Strip is
characterized by poor sanitation, insufficient treatment
and unsafe disposal. Currently, there are four wastewater
treatment plants in operation in the Gaza Strip namely:
Beit Lahia, Gaza, Khan Younis and Rafah Wastewater
Treatment Plants (WWTP’s) receiving about 24 Million
m3 of raw sewage per year.
2.2. Experimental Design
The experimental site was selected as sandy soil in the
north zone of the Gaza Strip. Two treatments were se-
lected: one irrigated with TWW and the other with fresh
water ( FW). Each treatment contains 4 replicates (plots).
Plot dimensions are 5 × 4 m. Each plot is divided into 5
rows for planting (12 plants in each row). The experi-
mental design was established as a randomized complete
block design. Chinese cabbage seedlings were planted
for first season on 28/11/2010 and harvested on 9/3/2011
and for the 2nd season on 11/11/2011 and harvested on
21/2/2012. Corn seeds were sown for the 1st season on
21/3/2011 and harvested on 25/6/2011 and for 2nd sea-
son 21/3/2012 and harvested on 25/6/2012.
2.3. Soil Analysis
Soil samples from depths of 0.0 - 30, 30 - 60, 60 - 90 and
90 - 120 cm depth were collected from eight soil profiles
dug in all plots. The soil samples were air dried, sieved
through 2 mm mesh and kept in plastic bags in the labo-
ratory for pH, EC and nutrient contents using the stan-
dard methods.
2.4. Irrigation Water and Analysis
Treated wastewater (TWW) from Beit Lahia wastewater
treatment plant and fresh water (FW) from local well
were used for irrigation. The irrigated plants are Chinese
cabbage as winter crop and corn (Zea maiz, Variety

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1738
Merit) as summer crop was grown on a sandy soil. Irri-
gation was managed by a drip irrigation system with
discharge of 4 L/plant/h according to the standard water
requirements [11].
Samples of TWW and FW were analyzed for physico-
chemical properties following the procedure described in
the standard method [12].
2.5. Harvesting, Plant Sampling and
Preparation
Plants were harvested after four months of planting day
or by the end of each season. The biomass of Chinese
cabbage and corn were collected and weighed and used
as growth indicator.
Chinese cabbage and corn leaves were sampled ran-
domly from several plants of each plot on the harvesting
day at the end of winter season, whereas, corn leaves
were sampled at the end of summer season. Leave sam-
ples were collected from several plants of each plot. The
samples were washed with tap water to remove atmos-
pheric dust sand and then washed with distilled water.
Leave samples were then oven dried at 65˚C for 48 hours,
ground and kept in well sealed plastic bags and stored at
room temperature for elemental analysis.
2.6. Elemental Analysis
About 0.5 g of oven dried leave sample as mentioned
above was digested with concentrated nitric acid in glass
tube at 80˚C for 48 - 72 h then heated up to 120˚C for 4 -
8 h to have clear solution as previously described [13].
Samples then were cooled and diluted with distilled wa-
ter up to 25 ml, filtered using small glass or plastic fun-
nels pre-washed with sulfuric acid. Elements concentra-
tion in the filtrate was determined using ICP. Two de-
terminations were conducted per replicate
2.7. Data Analysis
The data were statistically analyzed using mean and
standard deviations. Analysis of variance between treat-
ments was conducted using T-Test. P-values associated
with T-test were taken as an indicator of significant dif-
ferences among the treatments. P-values are presented
below Tables. P-values less than 0.05 are considered sig-
nificant.
3. Results and Discussion
3.1. Soil Analysis
Soil components and soil texture of the field plots are
shown in Table 1. It can be seen the clay fraction of soil
ranged between 2% - 5% in different depths of the soil
profiles. Accordingly soil can be classified as sandy soil.
Furthermore, the sand fraction of soils in all depths
ranged between 91% - 94% indicating sand texture of
soil.
Biological, physical and chemical properties of irriga-
tion water are shown in Tables 2.
BOD, COD, TSS, and EC stand for: biological oxygen
demand, chemical oxygen demand, total suspended sol-
ids and electric conductivity, respectively.
It can be seen that BOD, COD and TSS are nil in FW
whereas high values are observed in TWW. In addition,
nitrate level in FW is higher than in TWW. The explana-
tion of these results is that FW is nitrogen phosphorus
Table 1. Soil fractions and texture.
Depth (cm) Sand % Silt % Clay % Soil Texture
0 - 30 94 4 2 Sandy
30 - 60 92 5 3 Sandy
60 - 90 91 4 5 Sandy
90 - 120 92 4 4 Sandy
Table 2. biological and chemical properties of irrigation
water, 2011.
Properties FW TWW
BOD (mg/L) - 95.8
COD (mg/L) - 242.3
TSS (mg/L) - 108.7
pH 8.22 8.41
EC (dsim/m) 2.39 2.2
N-NO3 (mg/L) 38.9 1.6
N-NH4 (mg/L) - 51.6
K mg/l 3.8 21.7
Na (mg/L) 115 159
Ca mg/L 215 112
Mg 36 41
SAR 1.9 3.3
S mg/L 34 20
P mg/L 0.07 4.89
B (ppm) 0.07 0.17
Cl (ppm) 505 351
Cr (ppm) 0.005 0.001
Cu (ppm) 0.002 0.003
Fe (ppm) 0.002 0.009
Mn (ppm) 0.001 0.002
Ni (ppm) 0.016 0.018

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1739
potassium (NPK) fortified whereas in TWW the nitrate
level is being reduced to ammonium hydroxide due to an
aerobic condition. Accordingly low level of nitrate is
available in TWW. Sodium and Potassium are several
times higher in TWW than in FW. Calcium concentration
is higher in FW than in TWW whereas Magnesium has
opposite direction. Sulfur concentration is higher in FW
than TWW due to possible transformation of sulfate to
hydrogen sulfide in TWW due to an aerobic conditions.
Phosphorus and Barium are higher in TWW than in FW.
Chloride is higher in FW than in TWW due to chlorine-
tion process in drinking water. Heavy metal contents
ranged from 0.001 to 0.018 ppm in FW and TWW indi-
cating low contents. Comparison with EPA standards
shows that the properties of the used water are within the
range. Accordingly, the current water situation may be
used for agricultural irrigation. The following: Ag, As, Bi,
Cd, Co, Hg, Mo, Pb, Se and Sn were not detected in the
used water.
Table 3 shows pH and EC values for the soil profiles.
It is obvious that pH values ranged between 7.69 ± 0.21
to 8.05 ± 0.15 in FW and from 7.75 ± 0.1 to 8.1 ± 0.01 in
TWW plots.
It is obvious that soil is more acidic at the top layers
0.0 - 30 cm depth and less acidic at deeper depths in FW
and TWW plots. EC values are high in the top soil layers
(Table 3) and several times lower in deeper depths (90 -
120 cm) in both FW and TWW plots. This may be due to
accumulation of less soluble salts in the tope soil layer
and possible formation of organic acids due to biodegra-
dation of organic compounds in soils. These results are in
accord with Belyaeva et al. [9] who found lower pH in
the top soil due to addition of biosolids.
Statistical analysis for comparison between pH, and
EC values in soil profiles of 2011 does not show signifi-
cant differences in pH and EC values in TWW and FW.
P-values are 0.18 and 0.43 respectively.
Our results agree with Castro et al. [7] who investi-
gated the effects of wastewater irrigation on soil proper-
ties and turfgrass growth and concluded that there were
no negative effects with respect to changes in soil pH but
a significant increase in electrical conductivity and so-
dium content was observed in wastewater-irrigated soil.
Table 3. pH, and EC (dS/m) of soil profile, 2011.
FW TWW
Depth (cm)
pH EC (dS/m) pH EC (dS/m)
0 - 30 7.69  0.21 0.57  0.25 7.73  0.1 0.52  0.21
30 - 60 7.88  0.21 0.27  0.06 8.08  0.14 0.27  0.07
60 - 90 7.89  0.12 0.18 (0.02) 8.05  0.16 0.15  0.02
90 - 120 8.05  0.15 0.15  0.01 8.10  0.14 0.14  0.02
Nitrate concentrations (Table 4) decreased from the
top 0 - 30 to deeper depths in both treatments (TWW and
FW). Nitrate concentration of the soil 0 - 30 of FW-pro-
file is lower than TWW-profile as well as higher than
other depths.
Chloride concentrations of soil profile are higher in the
FW-samples than in the TWW-treated samples. Statistical
analysis for comparison between N-NO3, and Cl− values
in soil profiles of 2011 does not show significant differ-
ences in N-NO3, and Cl− values in TWW and FW. P-
values are 0.2 and 0.34 respectively. Our results agree
with Boruah and Hazarika [14] who concluded that avai-
lable N, K, S and exchangeable and water soluble Na, K,
Ca, Mg were highest in effluent irrigated soil.
Regardless to the highest values of organic matter that
found at depth 30 - 60 cm (Table 5), the mount of or-
ganic carbon decreased from the top to deeper depths in
both treatments (FW and TWW). Statistical analysis
shows no differences between treatments, P-value equals
to 0.45.
Our results agree with Adrover et al. [15] who inves-
tigated the chemical properties and biological activity in
soils of Mallorca following twenty years of treated waste-
water irrigation and did not observe negative effects on
cation exchange capacity, pH, calcium carbonate equiva-
lent, and soil organic matter.
Macronutrients, micronutrients and heavy metal con-
centrations in soil profiles are presented in Tables 6-8.
It can be seen that the concentrations of P (Table 6)
are ranged between 0.19 - 0.58 ppm in all depths of FW
and TWW treatments. This low value is due to low solu-
bility of P in soil solution due to high soil pH (Table 3).
These results agree with Metson et al. [16] who found
Table 4. N-NO3 and Cl− concentrations (mmol) in soil water
extract (1:1).
FW TWW
Depth (cm)
N-NO3 Cl− N-NO3 Cl−
0 - 30 0.76  0.223.0  1.78 1.01  0.43 2.8  1.35
30 - 60 0.46  0.261.09  0.56 0.64  0.38 1.1  0.44
60 - 90 0.41  0.050.62  0.26 0.49  0.15 0.34  0.21
90 - 120 0.32  0.020.43’ 0.35 0.41  0.23 0.39  0.11
Table 5. Total organic carbon (ppm) of soil profile, 2011.
Depth (cm) FW TWW
0 - 30 26.2  2.75 27.7  10.9
30 - 60 32.1  23.7 27.5  13.6
60 - 90 15.6  3.48 14.76  4.33
90 - 120 12.0  1.23 12.61  2.95

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1740
Table 6. Macronutrients concentration (ppm) in soil profile, 2011.
FW TWW
Element
0 - 30 30 - 60 60 - 90 90 - 120 0 - 30 30 - 60 60 - 90 90 - 120
P 0.22 ± 0.1 0.24 ± 0.1 0.43 ± 0.3 0.19 ± 0.06 0.17 ± 0.06 0.21 ± 0.07 0.58 ± 0.32 0.57 ± 0.46
K 6.5 ± 2.2 1.70 ± 0.6 1.80 ± 0.4 2.50 ± 1.2 5.9 ± 3.30 2.2 ± 0.70 2.2 ± 0.40 2.5 ± 1.0
Ca 60.7 ± 4.13 29.2 ± 7.0 19.5 ± 2.20 18.5 ± 2.70 48.5 ± 15.6 32.7 ± 4.10 20.1 ± 6.6 25.7 ± 11.0
Mg 9.25 ± 4.13 3.95 ± 0.88 2.58 ± 0.19 2.18 ± 0.25 3.24 ± 0.33 3.55 ± 1.66 2.81 ± 0.50 2.71 ± 0.63
S 13.4 ± 6.90 5.60 ± 1.10 4.10 ± 1.10 3.30 ± 0.60 2.19 ± 0.27 2.57 ± 2.82 1.15 ± 0.42 1.0 ± 0.57
Na 41.1 ± 20.8 20.8 ± 3.80 13.2 ± 2.30 13.5 ± 4.70 2.53 ± 1.07 1.38 ± 0.64 1.07 ± 0.30 1.1 ± 0.21
Table 7. Micronutrients concentration (ppm) in soil profile, 2011.
FW TWW
Element
0 - 30 30 - 60 60 - 90 90 - 120 0 - 30 30 - 60 60 - 90 90 - 120
Fe 0.104 ± 0.11 0.320 ± 0.32 0.622 ± 0.330.833 ± 0.370.05 ± 0.02 0.35 ± 0.28 1.44 ± 0.58 1.69 ± 1.19
Zn 0.031 ± 0.01 0.037 ± 0.02 0.034 ± 0.020.022 ± 0.010.023 ± 0.010.026 ± 0.01 0.032 ± 0.02 0.028 ± 0.01
Mn 0.020 ± 0.02 0.07 ± 0.09 0.03 ± 0.02 0.05 ± 0.02 0.01 ± 0,01 0.04 ± 0.02 0.14 ± 0.03 0.10 ± 0.08
Cu 0.011 ± 0.00 0.01 ± 0.00 0.01 ± 0.00 0.01 ± 0.00 0.011 ± 0.000.01 ± 0.00 0.01 ± 0.00 0.01 ± 0.00
B 0.04 ± 0.01 0.04 ± 0.02 0.03 ± 0.00 0.03 ± 0.01 0.05 ± 0.01 0.041 ± 0.02 0.03 ± 0.01 0.03 ± 0.01
Table 8. Heavy metals concentration (ppm) in soil profile, 2011.
FW TWW
Element
0 - 30 30 - 60 60 - 90 90 - 120 0 - 30 30 - 60 60 - 90 90 - 120
Co 0.002 ± 0.00 0.000 ± 0.00 0.000 ± 0.000.000 ± 0.000.002 ± 0.000.001 ± 0.00 0.001 ± 0.00 0.001 ± 0.00
Cr 0.001 ± 0.00 0.002 ± 0.00 0.003 ± 0.000.004 ± 0.000.002 ± 0.000.005 ± 0.00 0.004 ± 0.00 0.007 ± 0.00
Ni 0.013 ± 0.00 0.011 ± 0.00 0.013 ± 0.000.012 ± 0.000.011 ± 0.000.012 ± 0.00 0.017 ± 0.00 0.017 ± 0.00
Pb 0.109 ± 0.11 0.333 ± 0.33 0.648 ± 0.340.879 ± 0.370.047 ± 0.020.36 ± 0.28 1.54 ± 0.62 1.77 ± 1.26
Al 0.123 ± 0.13 0.398 ± 0.39 0.823 ± 0.431.161 ± 0.470.053 ± 0.030.47 ± 0.39 2.120 ± 0.80 2.378 ± 1.54
similar results of P in an urban ecosystem. Concentra-
tions of K, Ca, Mg, S and Na are higher in the top soil
layers than deeper depths in both treatments. Concentra-
tion of micronutrients in soil profile are shown in Table
7. It can be seen that except Fe, concentrations of Zn, Mn,
Cu, and B are below 0.15 ppm indicating poor nutrient
conditions. Furthermore, it can be seen that concentration
of Fe is increased from top soil layer to deeper depths,
indicating leaching of iron in Gaza Soils. However, the
poor concentration of micronutrients in soil is in agree-
ment with the general concept of sandy soils.
Concentrations of heavy metals are shown in Table 8.
It is obvious that concentrations of Co, Cr, and Ni are
below 0.02 ppm in both treatment (FW and TWW). These
values indicate low contents of heavy metals in soil.
Similar results were recently observed [17], who made a
geochemical survey in Italy and revealed the presence of
huge volumes of composite wastes which accumulated
up to a thickness of 25.6 m.
Furthermore, levels of Pb and Al are increasing gradu-
ally as increasing soil depth in both treatment (FW and
TWW) indicating leaching of these metals in Gaza soils.
An interesting conclusion of these results is that Fe, Pb
and Al pose threat to groundwater in Gaza.
3.2. Effect of TWW on Biomass
The total biomass of Chinese cabbage and corn are pre-
sented in Tables 9. Generally, it is obvious that there is
an increase in both plant growth from year 2011 to year
2012. Furthermore, the fresh weight of Chinese cabbage

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1741
in plots irrigated with TWW is higher than those irrigated
with FW in year 2011 and 2012.
Statistical analysis showed a significant difference be-
tween the average bio-mass of the two treatments (TWW
and FW). P-value equals to 0.015. Moreover, similar
trend is observed for corn plants (Table 9) indicating
high yields.
Statistical analysis showed significant differences be-
tween FW and TWW treatments. This suggests that
TWW can supply enough nutrients the same as the NPK
fortified FW treatment equivalent to the nutrient contents
of treated wastewater. This suggestion is supported by
the data in Table 2 (water analysis). In addition, our re-
sults agree with resent reports [7,18-20] who analyzed
the long term effects of two gradients: spatial (relative
distance from the water channel) and land use intensity
(cropping frequency) and addition of organic amendment
on soil properties and model crop (barley) response. They
demonstrated the clear and consistent patterns in soil pro-
perties and plant response along the gradients and points
out the probable long-term environmental trends in a
“would be” scenario for agricultural use of similar pol-
luted soils.
Comparison between the biomass 2011 and 2012 shows
a great increase in the biomass in year 2012. The expla-
nation of these results is that application of TWW may
enrich the soil with necessary nutrients that enabled plant
growth. Beside the fact that TWW contains some bacte-
ria as shown from the high BOD value (Table 2) that par-
ticipate in the degradation or organic matter that maintain
soil fertility. This explanation is supported by Mousavi et
al. [21] who showed that irrigation with TWW had a
significant positive impact on all characters of quality of
maize.
3.3. Determination of Micronutrients and
Heavy Metals in Plant Leaves
Levels of micronutrients and heavy metals in Chinese
cabbage leaves are shown in Tables 10 and 11 respec-
tively. The levels of micronutrients in Chinese cabbage
leaves in 2010-2011 (Table 10) indicate that Fe levels
are high in Chinese cabbage leaves in both treatments. Its
concentration did not exceed 192.35  62.81 in both FW
Table 9. Average weight of Chinese cabbage and corn
(Kg/plot).
Chinese cabbage Corn
Treatment
2011 2012 2011 2012
FW 33.9 ± 2.8 42 ± 9.132.9 ± 3.93 55.17 ± 12.9
TWW 38.6 ± 3.1 47 ± 10.446.73 ± 6.6 52.93 ± 10.73
Fresh Weight ± SD, P value between 2011 treatments = 0.015 for Chinese
cabbage; P value between 2011 treatments = 0.04.
Table 10. Micronutrients level (mg/kg) in Chinese cabbage
leaves 2010-2011.
FW TWW
Element
2010 2011 2010 2011
Fe 164.3  33.9192.35 ± 62.81 166.2  25.78 148.27 ± 22.89
Cu 3.54  0.493.79 ± 0.86 3.28  0.63 4.38 ± 0.62
Zn 30.7  5.338.16 ± 0.81 27.99  2.65 38.33 ± 7.15
Mn 32.53  6.4442.37 ± 8.17 36.57  8.02 35.15 ± 4.17
B nd 26.5 ± 5.4 nd 30.61 ± 7.05
Table 11. Heavy metals level in Chinese cabbage leaves
(Mean ± SD).
FW TWW
Element
2010 2011 2010 2011
Cr 0.673  0.120.55  0.25 0.58  0.1 0.54  0.16
Ni 1.42  0.490.77  0.24 1.06  0.34 0.81  0.21
Sn 0.58  0.334.34  1.47 0.82  0.33 6.87  3.95
Cd 0.08  0.010.12  0.08 0.07  0.01 0.06  0.00
Co nd 0.18  0.10 nd 0.14  0.02
and TWW treatments.
Concentrations of Cu did not exceed 4.38  0.62
mg/kg in both treatments (FW and TWW) during the 2
growing seasons. Concentrations of Zn reached 38.33 
7.15 mg/kg indicating elevated levels. Concentrations of
Mn are nearly similar in both TWW and FW but in year
2011 the levels reached to 42.37  8.17 mg/kg indicating
high concentrations. Concentration levels of B are high
in year 2011 and not detected in year 2010 in both treat-
ments. Concentrations of heavy metals in Chinese cab-
bage leaves are shown in Table 11. It can be seen that
concentrations of Cr, Ni, Sn and Cd did not exceed 2
mg/kg in year 2010 whereas only Sn exceeded 2 mg/kg
in year 2011 and reached 4.34 and 6.87 mg/kg in FW and
TWW respectively. These elevated levels indicating high
contamination levels. These results agree with Ferrara et
al. [17] who revealed that levels of As, Cd, Cr, Cu, Hg,
Pb, Sn, Tl and Zn exceeding the intervention legal limits
when irrigated with TWW.
Levels of micronutrients and heavy metals in corn
leaves are shown in Tables 12 and 13 respectively.
Concentrations of some micronutrients in corn leaves
are shown in Table 12.
It can be seen that concentrations of Fe ranged be-
tween 79.4  11.19 to 128.41  16.00 mg/kg indicating
wide variations. Concentrations of Cu ranged between
6.18  0.83 to 7.63  1.22 mg/kg indication similarity in
both treatments in the 2 growing season.

Effect of Treated Waste Water Irrigation on Plant Growth and Soil Properties in Gaza Strip, Palestine 1742
Table 12. Micronutrients level (mg/kg) in corn leaves 2010-
2011 (Mean ± SD).
FW TWW
Element
2010 2011 2010 2011
Fe 104.6  30.86 128.41± 16.00 79.4  11.19 124.8 ± 23.4
Cu 7.63  1.22 6.18 ± 0.836.23  1.34 6.21 ± 1.43
Zn 83.48  32.05 63.09 ± 12.24 57.04  28.31 50.8 ± 19.9
Mn 44.03  7.34 48.24 ± 6.42 45.53  9.38 55.6 ± 9.8
B nd 12.75 ± 2.74 nd 16.3 ± 6.5
Statistical analysis did not detect any significant difference at  = 0.05.
Table 13. Heavy metals level (mg/kg) in corn leaves 2010-
2011 (average ± SD).
FW TWW
Element
2010 2011 2010 2011
Cr 2.07  0.63 1.97 ± 0.322.07  0.41 1.14 ± 0.31
Ni 1.16  0.27 1.07 ± 0.141.77  0.68 0.91 ± 0.33
Sn 53.91  3.82 26.48 ± 14.24 39.55  12.25 18.6 ± 6.1
Statistical analysis detect significant difference at  = 0.05 only for Cr at
year 2011, P-value is Cr = 0.01.
Concentrations of Zn ranged between 50.8  19.9 and
83.48  32.05 mg/kg indicating wide variations among
the treatments.
Concentrations of Mn ranged between 44.03  7.34
and 55.6  9.8 mg/kg. This range is not as wide as in Zn
indicating similarity among the treatments. Concentra-
tions of B are detected only in Year 2011. Statistical ana-
lysis did not detect any significant difference at α = 0.05
level.
Concentrations of heavy metal in corn leaves are pre-
sented in Table 13. It can be seen that concentration of
Cr ranged between 1.14  0.31 and 2.07  0.63 mg/kg in
both treatment indicating low concentrations and varia-
tions. Concentrations of Ni ranged between 0.91  0.33
and 1.77  0.68 mg/kg in both treatments (FW and
TWW). Concentration of Sn ranged between 18.6  6.1
and 53.91  3.82 mg/kg indicating wide variations and
high concentrations.
Concentrations of Hg, Pb, As, and Se are under ICP
detection limit. These high levels of heavy metals may be
attributed to the irrigation with TWW. Our suggestion
agrees with Pritchard et al. [8] who concluded that atten-
tion must be given to heavy metal uptake by plant due to
irrigation with TWW.
4. Conclusions
The rational of this study emerges from the fact that the
country suffers from arid and semi arid conditions. Ac-
cordingly, the use of treated waste water is an option to
save water recourses for domestic uses. Our results dem-
onstrated that FW and TWW have physicochemical pro-
perties that allow for a safe use. Irrigation with TWW
demonstrates the effectiveness to increase the biomass of
Chinese cabbage and corn. Analytical results of soil pro-
file indicate leaching of Fe, Al, and Pb from the top soil
and accumulation in deeper depths. This situation may
pose health risk to groundwater.
Micronutrient and heavy metal contents in the plant
leaves are not extremely high and can be within the range
of local standards.
Although it is still too early to recommend the use of
TWW as an alternative option for irrigation, the pre-
sented results are promising and encouraging. Further
research work is needed before recommending TWW as
an alternative source of fresh water irrigation for vegeta-
bles. The future research may include the impact of long
term application of TWW on human health and envi-
ronment in terms of heavy metals and pathogens.
5. Acknowledgements
This research was funded by DFG Grant no. GZ:MA
1830/9-2.
Special thanks to Prof Dr Bernd Marschner, Bochum
University, Germny, for his suggestions during the re-
search activity.
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