wastewater reuse in irrigation through applying iwrm concept...iww oww bww gwl2 gwl3 water resources...
TRANSCRIPT
Wastewater Reuse in Irrigation
through Applying IWRM Concept “Effluent of Sana'a Treatment Plant
a case study” Al-Eryani A. A.; Al-Nozaily F.A.; and Al-Muselehi
S.W.H.
Email:
Introduction: Growing population and climate change are heightening water shortage
Globally there is an awareness raising to dispose wastewater safely
and beneficially.
Using treated wastewater in agriculture should be taken into
consideration to achieve the flowing advantages :
water saving through reduction of fresh water demand,
increasing food production through increasing irrigation water supply
increasing crops nutrients availability ,
and improving environment quality through enhancing wastewater
treatment plant and phytoremediation.
In arid and semi-arid countries like Yemen there is huge amount of
wastewater produced by big cities , and there is lack of fresh water
supply for human daily needs and for agricultural production , so
wastewater reuse for irrigation becomes necessary as alternative new
resource to solve this problem.
Research Problem Activated sludge - Extended aeration Sana’a wastewater
treatment system is considered as a flexible and powerful technology
But this treatment system is overloaded due to increasing of Sana’a city effluents, with no system updating
Also the application of design parameters is ignored due to :
pressure of drought effects experienced in Yemen
and increasing agriculture activities in the studied area
This overloading has resulted into declining of SWWTP efficiency, with the habit of using bypass wastewater in irrigation
So health and agronomic risks of using wastewater are expected to appear in the studied area.
Study Objectives: The main objective of the study is to study the
suitability of Sana’a treatment plant effluents reuse in irrigation through the following evaluations :
• Health impacts of SWTP effluent on people (farmers and crop consumers) in Bait Handhal area.
• Impacts of the effluents on soil productivity (salinity, sodicity, macro nutrients and trace elements concentrations).
• Socio-economic impacts of using wastewater in agriculture in the studied area through IWRM aspect s.
Methodology The methodology of this study consist of the following:
Wastewater sampling and analysis
To study the chemical and biological characteristics of wastewater, 18
wastewater and ground water samples were taken from 6 different resources
of Sana'a wastewater treatment plant effluent channel and ground water.
These resources are: inlet wastewater (IWW), outlet treated wastewater (OWW),
mixed of bypass untreated wastewater and treated wastewater (BWW),
groundwater from location1 (GWL1), groundwater from location2 (GWL2),
groundwater from location3 (GWL3 )
Soil sampling and analysis Two types of soil were selected, the first soil is irrigated with wastewater in Bait Handhal and the second soil in Bait Al-Jahillia which irrigated with groundwater 6 samples from each type of soil were taken and tested for physical and chemical analysis like EC, pH, K, Fe, OM, , SAR, P and soil texture.
Crop sampling
36 samples of 4 crops (sorghum, barley, alfalfa and cabbage) were taken to study
the health impacts (fecal coliform and total coliform) of crops irrigated with
wastewater in comparing with those irrigated with ground water,
and 12 samples of alfalfa and cabbage were taken to study the effects of irrigation
period (2and 10 days ) On TC and fecal coliform
the study area
Socioeconomic study by using 45 farmer Questionnaires (25
for men and 20 for women) were implemented in the studied
area for many details in this field
Statistical analysis
SPSS program is used (T-Test) to compare between the
following :
soil irrigated with wastewater and soil irrigated with groundwater
crops irrigated with wastewater and with groundwater
and using ANOVA procedure for comparing water resources
.
SWTP = Sana'a Wastewater Treatment Plant
= Wastewater samples
= Soil samples
= Crops samples
Figure 3.1 the locations of wastewater
(ww) samples in Bait Handhal
Figure 3.2 the locations of soils
samples in Bait Handhal
Figure 3.3 the locations of soils
samples in Bait Al-Jahli
Figure 3.4 the locations of crops
samples in Bait Handhal
Figure 3.3 the locations of soils
samples in Bait Al-Jahelia
Studied
traits
df Significanc
e level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
EC (µs/cm) 5 ** 2293 2067 2210 2130 2150 2253 67.3
TDS ( mg/l) 5 ** 1491 1343 1437 1393 1398 1465 46.1
pH 5 ** 7.3 7.5 8.3 8.2 6.8 7.8 0.26
Table and Fig. ( 1.1) Analysis of variance for studied traits differences
among water resources samples and their means
Result and Discussion
0
500
1000
1500
2000
2500
3000
3500
4000
4500
IWW OWW BWW GWL1 GWL2 GWL3
Water Resources
TDS
EC
6
6.5
7
7.5
8
8.5
9
IWW OWW BWW GWL1 GWL2 GWL3
Water resources
pH
Studied
traits
df Significance
level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
NH3 ( mg/l) 5 ** 147 133 159 117 100 94 21.19
NO3 ( mg/l) 5 ** 6 8 10 13 16 13 2.42
SO4 ( mg/l) 5 ** 169 66 85.67 96 102.8 86.17 27.26
Table and Fig.(1.2) Analysis of variance for studied traits differences among
water resources samples and their means
0
50
100
150
200
IWW OWW GWL1 GWL2 GWL3
Water Resources
NH3
NO3
SO4
Studied
traits
df Signific
ance
level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
Ca ( mg/l) 5 ** 80 74 83.33 112.67 125 100.33 14.11
Mg ( mg/l) 5 * 30 27 39.33 36 37.33 39.67 5.05
K ( mg/l) 5 ** 46 42.67 35 28.67 36 35.33 3.79
Na ( mg/l) 5 ** 230 250.67 241 206.67 218.33 238.33 8.90
Table and Fig. (1.3) Analysis of variance for studied traits differences among water resources samples and their
means
0
50
100
150
200
250
300
IWW OWW BWW GWL1 GWL2 GWL3
Water resources
Ca
Mg
Na
K
Studied
traits
df Significanc
e level
IW
W
OWW BWW GWL1 GWL2 GWL3 Lsd0.05
SS ( mg/l) 5 ** 817.0 78.67 100.00 82.67 70.00 145.00 54.97
Table and Fig. ( 1.4) Analysis of variance for studied traits differences among water
resources samples and their means
0
200
400
600
800
1000
IWW OWW BWW GWL1 GWL2 GWL3
Water Resources
SS
Studied
traits
df Significanc
e level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
BOD5 (
mg/l)
5 ** 1427 102.67 89.33 88.33 128 97.33 289.46
COD (
mg/l)
5 ** 2458 220 260 233.33 236.67 247.00 258.27
Table and Fig. ( 1.5) Analysis of variance for studied traits differences among water
resources samples and their means
-1000
0
1000
2000
3000
IWW OWW BWW GWL1 GWL2 GWL3
Watrer Resources
BOD5
COD
Studied
traits df
Significance
level IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
Fecal
Coliform
(Col/100m)
5 ** 63666666
7 82000 146666 89333 47700 11366 3.8*108
Table and Fig. (1. 6)Analysis of variance for studied traits differences among water
resources samples and their means
0
200000000
400000000
600000000
800000000
IWWOWW
BWW GWL1 GWL2 GWL3
WaterResources
Fecal Coliform
Studied
traits
df Signifi
cance
level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
Mn (ppm) 5 ns 0.08 0.006 00.40 000.1 0.002 0.0013 ns
Cu (ppm) 5 ** 0.004 0.0063 0.0018 0.0008 0.0008 0.000 0.001
Ni (ppm) 5 ** 0.267 0.35 0.17 0.08 0.107 0.063 0.121
Table and Fig. (1. 7)Analysis of variance for studied traits differences among water
resources samples and their means
-0.05
0
0.05
0.1
0.15
IWW
OW
W
BW
W
GW
L1
GW
L2
GW
L3
Water Resources
Mn
-0.002
0
0.002
0.004
0.006
0.008IW
W
OW
W
BW
W
GW
L1
GW
L2
GW
L3
Water Resources
Cu
0
0.1
0.2
0.3
0.4
0.5
IWW
OW
W
BW
W
GW
L1
GW
L2
GW
L3
Water Resources
Ni
Studied
traits
df Signifi
cance
level
IWW OWW BWW GWL1 GWL2 GWL3 Lsd0.05
Zn (ppm) 5 ** 0.0047 0.047 0.004
2
0.0023 0.0016 0.0000 0.01
Cd (ppm) 5 ns 0.0022 0.0018 0.001
2
0.0006 0.0022 0.002 ns
Pb (ppm) 5 ns 0.055 0.0032 0.002
5
0.0018 0.0021 0.001 ns
Table and Fig. (1.8) Analysis of variance for studied traits differences among water
resources samples and their means
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
IWW OWW BWW GWL1 GWL2 GWL3
Water Resources
Zn
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
Water Resources
Cd
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Water Resourcrs
Pb
Studied Traits df Significance
level WWIS Mean
GWIS Mean
PH 10 ** 7.8683 8.1917
EC (µs/cm) 10 ** 841.833 563.333
TDS (mg/l ) 10 ** 547.166 366.000
0
200
400
600
800
1000
1200
WWIS GWIS
EC(µs/cm)
TDS(mg/l )
7.2
7.4
7.6
7.8
8
8.2
8.4
8.6
WWIS GWIS
PH
Table and Fig. (2.1) Group T- Test analysis for the studied traits differences among wastewater irrigated
crop (WWIC) and groundwater irrigated crop(GWIC) and their means
Soil Samples
Table and Fig. (2.2) Group T- Test analysis for the studied traits differences among wastewater
irrigated crop (WWIC) and groundwater irrigated crop(GWIC) and their means
Studied Traits df Significance
level WWIS Mean
GWIS Mean
Total N (mg/l) 10 ** 31.166 14.250
P (mg/l) 10 ** 25.233 3.516
K ( mg/l) 10 ** 414.166 96.626
Ca (meq/l) 10 ** 3.506 2.693
Mg ( meq/l) 10 ** 1.176 1.073
-10
0
10
20
30
40
50
N P Ca Mg
WWIS
GWIS
-100
0
100
200
300
400
500
600
700
WWISGWIS
K (mg/l)
Studied Traits df Significance
level WWIS Mean
GWIS
Mean
Na ( mg/l) 10 ** 402.500 427.833
SAR (meq/l) 10 ** 11.631 13.935
OM (mg/l) 10 ** 1.221 0.595
Table and Fig. (2.3) Group T- Test analysis for the studied traits
differences among wastewater irrigated crop (WWIC) and groundwater
irrigated crop(GWIC) and their means
385
390
395
400
405
410
415
420
425
430
WWIS GWIS
Water Resources
Na
10
10.5
11
11.5
12
12.5
13
13.5
14
14.5
WWIS GWIS
Water Resources
SAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
WWIS GWIS
Water Resources
OM
Table and Fig. (2.4) Group T- Test analysis for the studied traits differences among wastewater
irrigated crop (WWIC) and groundwater irrigated crop(GWIC) and their means
Studied Traits df Significance
level WWIS Mean
GWIS Mean
Fe (mg/l) 10 ** 10.908 2.960
Cu ( ppm) 10 ** 0.9300 0.2200
Zn (ppm) 10 ** 0.9500 0.4583
Co ( ppm ) 10 ** 0.1950 0.0650
Ni ( ppm) 10 ns 0.2267 0.0967
Mn (ppm) 10 * 3.7000 2.2500
Cd ( ppm) 10 ** 0.0342 0.4042
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Cu Zn Co Ni
WWIS
GWIS
0
2
4
6
8
10
12
14
16
Fe Mn-0.2
0
0.2
0.4
0.6
0.8
WWIS GWIS
Cd
Studied Traits df Significance level Crop WWIC GWIC
Fecal Coliform 4 ** Cabbage 47.333 4.000
4 ** Alfalfal 13.667 2.667
4 ** Barley 20.333 9.000
4 ** Sorghum 13.667 2.667
Table and Fig. (3.1) Group T- Test analysis for the studied traits differences among wastewater
irrigated crop (WWIC) and groundwater irrigated crop(GWIC) and their means
0
10
20
30
40
50
60
Cabbage Alfalfa Barley Sorghum
Fecal Coliform
WWIC
GWIC
Crops Samples
Studied
Traits df Significance level Crop WWIC
mean GWIC
men Total
Coliform 4 ** Cabbage 93.333 12.333
4 ** Alfalfal 380.000 18.667
4 ** Sorghum 24.333 8.667 4 ** Barley 36.667 15.667
Table and Fig. (3.2) Group T- Test analysis for the studied traits differences
among wastewater irrigated crop (WWIC) and groundwater irrigated crop(GWIC)
and their means
-100
0
100
200
300
400
500
Cabbage Alfalfa Sorghum Barley
Total Coliform
WWIC
GWIC
Studied Traits df Significance
level Crop 2 days 10 days
Fecal Coliform 4 ** Cabbage 163.3333 47.3333
4 ** alfalfa 190.0000 40.6667
Total Coliform 4 ** Cabbage 320.0000 93.3333
4 ** alfalfa 380.0000 80.0000
0
50
100
150
200
250
Cabbage alfalfa
Fecal Coliform
2 days
10 days 0100200300400500
Total Coliform
2 days
10 days
Table and Fig. (3.3) Group T- Test analysis for the studied traits differences among wastewater
irrigated crop (WWIC) and groundwater irrigated crop(GWIC) and their means
Conclusions Due to by-pass practice and poor performances of Sana'a
wastewater treatment plant, most of the physical, chemical, and biological characteristics of treated wastewater used for irrigation in the studied area didn't meet the professional quality standards of Yemeni standards draft (by the EPC.)
Under irrigation with wastewater, vegetable crops consumers, farmers and handlers may face high risk pathogen infections.
The results of the questionnaire in the health aspect revealed that most farmers are :
severing from skin problems,
complain gathering of insects (mosquitoes) that could transfer diseases from one place to another.
Some of them suffering from intestinal problems ( like diarrhea ) and fever.
The animals had absolutely intestinal problems due to drinking from the open wastewater channel.
Slight to moderate agronomic problems are expected due to soil salinity (EC < 2000 µs/cm) and severe crop toxicity of sodium (SAR > 9 meq/l)
The high suspended solids and organic matter in the effluent of Sana'a wastewater treatment plant (SS=215 mg/l) and (BOD=322 mg/l & COD=609 mg/l)). Lead to clogging problems of the soil pores and reducing water percolation and aeration.
Comparing between soil irrigated with wastewater and that
irrigated with groundwater revealed that :
- Sodium toxicity and permeability problem are expected in both of soils (SAR >9 meq/l)
- But the presence of calcium with high concentration in wastewater may reduce permeability problem caused by excessive amount of sodium.
- Sodium concentration of groundwater irrigated soil ( 427.8 mg/l ) is higher than that irrigated with wastewater ( 402.5 mg/l) , despite the concentration of sodium in wells is less than in wastewater, that probably due to salt accumulation from frequent deficit irrigation ( there is no salt leashing due to water scarcity )
According to the result of executed questionnaire in the study area most respondent said :
i. There are no effective regulations, and the enforcement of these regulations is seem to be difficult under water shortage and lack of job opportunities.
ii. There is a good income from selling of vegetable and fodder crops which are irrigated with wastewater .
iii. The farmers didn't need to use fertilizer under irrigation with wastewater, but at the same time they have to buy potable water because ground water in the studied area is contaminated with wastewater .
Recommendations Sana'a wastewater treatment plant effluent should receive a degree of
treatment that meet Yemeni standards recommended quality (drafted by the EPC).
In the meantime all wastewater arrived Sana’a treatment plant should be treated through expanding it’s capacity , and by-pass Practices should be stopped.
Irrigation by wastewater should be stopped for uncooked eaten vegetables;.
The cultivation of sorghum, Barley, wheat and alfalfa should dried as hay for animal ,and the grain of these crop should stored and cooked for human to avoid pathogenic risks.
Irrigation interval has to be long as much as possible to reduce health hazards especially before cutting.
Conventional wastewater irrigation methods should be replace with those suitable to reduce the contact with wastewater contamination
More awareness programs, should be done by the concerned bodies in regard wastewater reuse issues.
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