Environmental Engineering Reference
In-Depth Information
(a)
(b)
40
6
1st runoff
1st runoff
30
4
20
2
10
0
0
Standard RG
Fe-Osorb RG
Standard RG
Fe-Osorb RG
40
6
2nd runoff
2nd runoff
30
4
20
2
10
0
0
Standard RG
Fe-Osorb RG
Standard RG
Fe-Osorb RG
10
1.0
3rd runoff
3rd runoff
8
0.8
6
0.6
4
0.4
2
0.2
0
0.0
Standard RG
Fe-Osorb RG
Standard RG
Fe-Osorb RG
FIGURE 33.9
Nitrate (a) and phosphate (b) concentrations in efluent of standard and Fe-Osorb-enhanced bioretention sys-
tems (rain garden, RG) during three simulated runoff events. The irst two runoff events (3.0-in total rainfall)
were applied to each bioretention system using tap water 2 days apart with spiked concentrations of nitrate
(34 g for each) and phosphate (34 g for each). No pollutants were applied for the third simulated runoff to evalu-
ate potential leaching of nutrients.
33.13 Bacterial Growth Testing
The effects of Osorb on bacterial growth were evaluated in the presence of a biocide, triclo-
san. Ampicillin-resistant DH5 (alpha)
Escherichia coli
grown in Luria-Bertani (LB) media
were used and tested at three different conditions: (i) control LB media, (ii) LB media + 100
ppb of triclosan, and (iii) LB media + 100 ppb of triclosan + 3 g (0.3% w/v) of Osorb, which
was presterilized using ethanol. Each experiment was performed by irst growing a starter
culture of bacteria: 1.0 mL of the starter culture was added to 1.0 L of sterile LB media.
Bacteria were grown in ampicillin (1 μg/mL) to ensure selection of only the experimental
strain. Bacterial cell density was measured over time using the OD
600
(optical density at
600 nm) method.
The results show that the bacteria grew best with Osorb even with triclosan added (Figure
33.10). Without Osorb, all the bacteria died (no growth) in the presence of 100 ppb triclosan
