Impacts of desalination effluents on
macrobenthic assemblages in Bahrain,
Arabian Gulf
Humood Naser
Department of Biology, College of Science,
University of Bahrain
1
Introduction
• Arabian Gulf countries are characterized by
low precipitation and high aridity.
• Most of the fresh water needs are being
obtained from seawater through the various
processes of desalination.
• Desalinations include Multi-Stage Flash
(MSF), Reverse Osmosis (RO) technologies.
2
Desalination in Bahrain
Plant
Operation
Technology
date
Water
Effluents
capacity
m3 day-1
gallon day-1
Sitra Power and
1975
multi-stage flash
25 x 106
66 000
1984
underground water
12 x 106
1 500
Water Station
Ras Abu-Jarjur
Desalination Plant
Addur Desalination
reverse osmosis
1990
Seawater reserve osmosis
10 x 106
3 750
2000
multi-stage flash
30 x 106
8 000
plant
Al-Hidd Power and
Water Station
Total
79 250
3
• Water discharges associated with chemical
products from desalination plants are
increasingly becoming a serious threat to
coastal and marine ecosystems in the Arabian
Gulf.
• Receiving marine environments are typically
subject to chemical and physical alterations
that can subsequently affect benthic
communities.
4
• Macrobenthic assemblages are useful and
sensitive indicators for the quality of intertidal
and subtidal marine environments.
• The aim of this study was to assess the impacts
of two desalination plants (MSF and brackish
RO) on the abundance and biodiversity of
macrobenthos inhabiting subtidal areas off the
eastern coastline of Bahrain.
5
Materials and Methods
Two desalination plants were selected
6
7
Sitra Power and Water Station (SPWS) (MFS)
Inlet
Outlet
8
Sitra Power and Water Station (SPWS) (MFS)
9
Ras Abu-Jarjur Desalination Plant (RADP) (RO)
Outlet
10
Ras Abu-Jarjur Desalination Plant (RADP) (RO)
Outlet
11
Sampling design
Transect: 8 stations: 200m
Desalination
outlet
Station: sediment sampling for benthos, physical and chemical analyses
12
Macrobenthos sampling
13
Macrobenthos sampling
14
Macrobenthos identification
15
Macrobenthos identification
16
Macrobenthos identification
17
Grain size analysis
18
Heavy metal digestion
19
Heavy metals analysis
20
Nutrient analysis in seawater
21
Results
22
SPWS (MSF)
RAJDP (RO)
Environmental
parameters
Depth (m)
Water Temp. oC
Salinity (PSU)
% Organic
content
Mean sediment
particle (ø)
1
5.0
35
48
2
1.1
27
46
3
0.9
21
45
4
3.3
21
45
5
6
7
7.5 10.8 9.9
21 21 21
45 45 45
8
8.3
21
45
1
1.3
21
45
2
1.9
21
45
3
4.0
21
45
4
5.0
21
45
5
5.5
21
45
6
5.3
21
46
7
5.9
21
46
8
6.4
21
46
1.20 1.90 2.10 2.67 4.03 4.70 6.36 4.71
3.96 5.90 4.24 3.55 2.19 2.93 3.82 3.91
0.20 0.21 0.21 0.23 2.66 2.77 3.19 2.10
2.23 2.24 2.25 1.08 1.68 2.07 2.78 2.71
23
Nutrients in seawater
Ammonia
7.00
6.00
5.00
4.00
mg/l
SPWS
RADP
3.00
Standard
2.00
1.00
0.00
1
2
3
4
5
6
7
8
24
Nutrients in seawater
Nitrate
1.20
1.00
mg/l
0.80
SPWS
0.60
RADP
Standard
0.40
0.20
0.00
1
2
3
4
5
6
7
8
25
Nutrients in seawater
Phosphate
2.50
2.00
1.50
mg/l
SPWS
RADP
Standard
1.00
0.50
0.00
1
2
3
4
5
6
7
8
26
Metals in sediment
Zn
90
80
70
mg/kg
60
50
SPWS
RADP
40
30
20
10
0
1
2
3
4
5
6
7
8
27
Metals in sediment
Cu
40
35
30
mg/kg
25
SPWS
20
RADP
15
10
5
0
1
2
3
4
5
6
7
8
28
Metals in sediment
Cd
9.000
8.000
7.000
mglkg
6.000
5.000
SPWS
RADP
4.000
3.000
2.000
1.000
0.000
1
2
3
4
5
6
7
8
29
Metals in sediment
Pb
40
35
30
mg/kg
25
SPWS
20
RADP
15
10
5
0
1
2
3
4
5
6
7
8
30
Ecological indices
SPWS (MSF)
RAJDP (RO)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Number of species
4
5
8
10
10
9
5
9
20
17
16
24
25
23
19
18
Number of org. 0.02m-2
28
30
28
29
85
101
11
59
201
156
126
259
197
230
86
178
Species richness
0.90
1.18
2.10
2.67
2.03
1.73
1.67
1.96
3.58
3.17
3.10
4.14
4.54
4.05
4.04
3.40
Species evenness J'
0.75
0.75
0.81
0.91
0.83
0.54
0.85
0.77
0.65
0.79
0.80
0.82
0.79
0.80
0.81
0.72
Diversity H'(loge)
1.04
1.21
1.68
2.10
1.92
1.18
1.37
1.70
1.95
2.23
2.22
2.60
2.55
2.50
2.39
2.07
31
32
Community structure
2D Stress: 0.09
1
4
1
2
2
Similarity
3
6
Transect
3
40
4
5
8
7
2
5
1
68
7
33
Concluding remarks
• Reduced levels of biodiversity and abundance were
recorded in sampling stations adjacent to the outlet of
MSF.
• Brine effluents that associated with high temperatures,
salinities, and a range of chemical and heavy metal
pollutants may affect marine benthos.
• Although localized severe impacts on benthos were
detected, collective discharges of desalination
effluents, may synergistically contribute to the
degradation of the naturally stressed marine
ecosystems and natural resources in the Arabian Gulf.
34
Thank you
35