Environmental Engineering Reference
In-Depth Information
highest and PET has the lowest barnacle attachment (
Table 4.2
), probably because
PU is the most hydrophobic and PET is the most hydrophilic material. The amounts
of polychaetes on these materials are highest in May or November. May is the start
of south-west monsoon and November is the start of north-east monsoon [15].
Flow velocities of less than 1.2 m/s allow larval settlement. Once settled, these shell
colonies can withstand velocities as high as 2.5 m/s. Flow velocities below 0.1 m/s
are not suficient to provide adequate food and oxygen for their growth [15].
Table 4.2 Effect of season on biofouling (micro and macro) on polymers/
composites placed for one year in the surface water of the Bay of Bengal
(South India) (SR, PU and PET)
TSS (mg/cm
2
)
Name of
polymers/
composites
Month
Total fouling
load (mg/cm
2
)
Barnacle
(Number/
plate)
Polychaetes
(Number/
plate)
SR
September
38.73 ± 6.82
27.40 ± 6.51
21.7 ± 17.60
17.0 ± 5.00
November
29.07 ± 6.78
4.24 ± 1.00
1.0 ± 1.00
5.0 ± 2.00
January
42.40 ± 27.35
14.80 ± 0.40
0.3 ± 0.60
−
March
34.93 ± 4.69
7.88 ± 1.50
−
0.3
May
20.67 ± 9.93
16.20 ± 1.80
8.7 ± 4.00
26.0 ± 3.60
July
36.38 ± 0.63
24.40 ± 2.40
0.3 ± 0.20
4.0 ± 2.30
PU
September
44.73 ± 14.40
22.18 ± 5.12
42.0 ± 8.5
7.0 ± 4.0
November
37.07 ± 5.13
2.64 ± 0.96
6.0 ± 1.0
7.0 ± 4.0
January
50.47 ± 7.06
15.40 ± 0.9
4.0 ± 3.0
2.7 ± 1.5
March
35.22 ± 11.98
7.94 ± 1.8
2.0 ± 2.0
7.3 ± 4.9
May
41.78 ± 21.44
21.70 ± 2.1
18.0 ± 10.0
35.3 ± 10.1
July
100.58 ± 35.18
28.50 ± 4.1
14.3 ± 5.9
10.3 ± 2.1
PET
September
72.11 ± 24.02
37.73 ± 8.92
17.3 ± 11.3
13.7 ± 4.2
November
39.53 ± 2.28
4.73 ± 0.7
5.0 ± 1.5
51.3 ± 9.2
January
63.09 ± 13.02
15.93 ± 0.7
2.7 ± 1.5
2.0 ± 1.0
March
86.73 ± 0.10
10.90 ± 0.0
−
2.3 ± 1.3
May
53.67 ± 3.30
20.30 ± 0.9
9.5 ± 5.7
38.5 ± 12.0
July
134.07 ± 46.90
29.40 ± 1.1
11.7 ± 5.0
5.7 ± 2.1
