الفهرس 
Water analysisOnly 14 pages are availabe for public view
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Abstract
The present study aims to detect the microbial risks resulting from
irrigation of tomatoes and lettuce plants with untreated sewage water in a
field in Al-Sharqia Governorate. This study also, made a comparison
between two fields: one of them was irrigated with sewage water and the
other was irrigated with underground water.
For this purpose, eight water samples were collected from two sources of
water (sewage and underground water) in Al-Sharqia Governorate. The
samples were collected in two liters sterile borosilicate glass bottles and
examined for physico-chemical parameters, heavy metals concentrations
and biological analysis. Twelve samples of tomato fruit were collected
from two fields: six of them were irrigated with sewage water and the
other six were irrigated with underground water. Also, twelve lettuce
samples were collected from two different fields: six samples were
irrigated with sewage water and the other six were irrigated with
underground water.
A biological treatment method had been done for sewage water samples
using blue green alga (Spirulina platensis) and green alga (Chlorella
vulgaris), to reduce bacterial contamination and heavy metals
concentrations in them.
Treatment for bacteria:
Sewage water samples were divided into two groups:
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Group (1): two samples were inoculated by 2.5 ml and the other two by
10 ml of Spirulina platensis. They were incubated at 25 - 30°C for two
incubation periods (15 and 21 days).
Group (2): another four samples had been inoculated, two of them by 2.5
ml and the other two samples by 10 ml of Chlorella vulgaris. They were
incubated at 25 - 30°C for two incubation periods (15 and 21 days).
An examination of total and fecal Coliform bacteria had been done to the
previous two groups after 15 and 21 days.
Treatment for heavy metals:
The main sewage water sample had been examined for the heavy metals
concentrations (Pb, Al, Cu and Cd) before the beginning of the treatment
process and then, samples which inoculated by Spirulina platensis and
Chlorella vulgaris had been examined for the presence of the four heavy
metals (Pb, Al, Cu and Cd) after 15 and 21 days.
The results of this study were obtained as follows:
I- Water analysis:
a- Detection of some physico-chemical parameters in water:
1-Turbidity:
-Sewage water: two out of four samples were turbid and the other two
were semi-turbid.
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-Underground water: two samples appeared clear and the other two
appeared semi-turbid.
2-Hydrogen ion concentration (pH):
-Sewage water: the pH values of the samples were slightly acidic and
their mean ± SD was 6.5 ± 0.2.
-Underground water: most of the samples had a neutral pH. Three out of
four samples had a pH value of 7 and only one sample had a pH value of
6.8.
3-Temperature:
-Sewage water: temperatures of sewage water samples were high and
their mean ± SD was 33.0 ± 2.4°C.
-Underground water: temperatures of the underground water samples
were moderate and their mean ± SD was 25.8 ± 1.0°C.
4-Biological oxygen demand (BOD):
-Sewage water: all the samples had high BOD values and their mean ±
SD was 267.5 ± 53.8 mg/l.
-Underground water: the BOD values of the samples were low and their
mean ± SD was 4.5 ± 0.6 mg/l.
5-Chemical oxygen demand (COD):
-Sewage water: the sewage water samples had high COD values and
mean ± SD was 419.5 ± 12.2 mg/l.
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-Underground water: the COD values of the underground water samples
were low and had mean ± SD equal 5.3 ± 0.5 mg/l.
6-Dissolved oxygen (DO):
-Sewage water: there was no dissolved in any of the sewage water
samples.
-Underground water: the dissolved oxygen values in the underground
water samples were high and their mean ± SD was 2.3 ± 0.1 mg/l.
7-Electrical conductivity (EC):
-Sewage water: the electrical conductivity values of the samples were
high and their mean ± SD was 1325.0 ± 65.5μ mol / cm.
-Underground water: the electrical conductivity values of the
underground water samples were low and their mean ± SD was 375.5 ±
19.5μ mol / cm.
8-Total dissolved solids (TDS):
-Sewage water: the concentrations of the total dissolved solids in the
samples were high. They exceeded 790 mg/l and their mean ± SD was
834.3 ± 37.6 mg/l
-Underground water: the concentrations of the total dissolved solids in
the samples were low and their mean ± SD was 246.5 ± 3.7 mg/l.
9-Phosphate:
-Sewage water: the concentrations of phosphate in the samples were high
and their mean ± SD was 21.6 ± 1.5 mg/l.
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-Underground water: the concentrations of phosphate in the underground
water samples were low and their mean ± SD was 0.2 ± 0.03 mg/l.
10-Nitrare:
-Sewage water: the concentrations of the nitrate in the sewage water
samples were high and had mean ± SD value of 29.3 ± 1.1 mg/l.
-Underground water: the concentrations of the nitrate in the underground
water samples were low and their mean ± SD value was 0.1 ± 0.01 mg/l.
b- Bacterial analysis of water:
1-Plate count (saprophytes) at 22°C:
-Sewage water: all sewage water samples showed growth for saprophytes
at 22°C above the permissible limits (>100 cfu/ml).
-Underground water: the growth of saprophytes at 22°C was below the
permissible limits.
2-Plate count (saprophytes) at 37°C:
-Sewage water: all sewage water samples showed growth for saprophytes
at 37°C above the permissible limits (>100 cfu/ml).
-Underground water: the underground water samples showed growth of
saprophytes at 37°C under the permissible limits.
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3-Coliform count (cc/100ml):
-Sewage water: all samples showed large growth of Coliform bacteria
(>50 cc/100ml) and exceeded the permissible limits.
-Underground water: the underground water samples had a Coliform
count within the permissible limits. Their mean ± SD was 43.25 ± 3.85
cc/100ml.
4-E.coli count (cc/100ml):
-Sewage water: all the samples had great growth of E.coli bacteria (>50
cfu/100ml) and exceeded the permissible limits.
-Underground water: the underground water samples showed moderate
E.coli growth and their mean ± SD was 32.5 ± 8.19 cc/100ml.
c- Identification of algal species in water:
-Sewage water: Spirulena major had been found in three out of four
samples while Anabena sp. in two, Melosira granulata, Synedra ulna and
Oscillatoria tenuis in three and Chroococcus minutus in only one.
-Underground water: examination of underground water samples showed
no growth for any algal species.
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d- Heavy metal analysis for water:
-Sewage water: the concentrations of lead and copper in the origin
sewage were 0.2044 and 0.057 mg/l respectively but cadmium and
aluminum were not detected (< 0.001 mg/l).
-Underground water: the concentrations of the four heavy metals: lead,
copper, cadmium and aluminum were not detected in the underground
water (< 0.001 mg/l).
II- Vegetable analysis:
a- Detection of E.coli and Salmonella sp. in lettuce plant:
1-Detection of E.coli:
-Lettuce samples irrigated with sewage water: three out of six lettuce
samples were contaminated by E.coli with a percentage of 50%.
-Lettuce samples irrigated with underground water: there were no
microbial growth E.coli bacteria inside any of the lettuce samples.
2- Detection of Salmonella sp.:
-Lettuce samples irrigated with sewage water: all of the six samples were
completely free from Salmonella sp..
-Lettuce samples irrigated with underground water: all samples were
completely free from Salmonella sp..
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b- Detection of E.coli and Salmonella sp. in tomato fruit:
1-Detection of E.coli:
-Tomato samples irrigated with sewage water: four out of six samples
were positive for E.coli contamination with a percentage of 66.6%.
-Tomato samples irrigated with underground water: two out of six
samples were positive for E.coli contamination with a percentage of
33.3%.
2- Detection of Salmonella sp.:
-Tomato samples irrigated with sewage water: three out of six samples
were positive for Salmonella sp. contamination with a percentage of
50%.
-Tomato samples irrigated with underground water: four out of six
samples were positive for Salmonella sp. contamination with a
percentage of 66.6%.
III-Treatment of sewage water by algae:
(a)Treatment for bacteria:
1- Treatment of sewage water by blue green alga Spirulina platensis:
a- Fecal Coliform:
The highest effect of the blue green alga (Spirulina platensis) on fecal
Coliform was at concentration of 10 ml/500ml after 15 days where it
reached to zero value and after 21 days, the same effect was noticed at
concentration of 2.5 ml/500ml of the alga.
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b- Total Coliform:
The highest effect of blue green alga (Spirulina platensis) on total
Coliform was 73 at 2.5ml/500ml of algal concentration after 21 days but
after 15 days the highest effect was 440 at 10 ml/500ml of algal
concentration.
2- Treatment of sewage water by green alga (Chlorella vulgaris):
a- Fecal Coliform:
The strongest effect of the green alga (Chlorella vulgaris) on fecal
Coliform was zero value at 2.5ml/500ml of algal concentration and at
incubation periods of 15 and 21 days.
b- Total Coliform:
The highest effect of the green alga (Chlorella vulgaris) on total
Coliform was 310 at 2.5ml/500ml of algal concentration after 15 days but
after 21 days, the best effect was 490 at 2.5 ml/500ml of algal
concentration.
(b)Treatment for heavy metals:
1- Treatment of sewage water by blue green alga Spirulina platensis:
The highest effect on lead reduction was 0.008 at 10ml/500ml of algal
concentration after 21 days while for copper the highest reduction was
0.0148 at 2.5 ml/500ml of algal concentration after 21 days.
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2- Treatment of sewage water by green alga (Chlorella vulgaris):
The highest reduction for lead was 0.002 at 10 ml/500ml of algal
concentration after 21 days, also the highest reduction for copper was
0.009 after 21 days at 2.5 ml/500ml of algal concentration.