Table 6.
Heavy-metal concentrations in extra-heavy oil after enzymatic treatment.
| Enzyme | Ni | Fe | V | |||
|---|---|---|---|---|---|---|
| Concentration (mg kg−1) |
Removal Rate (%) | Concentration (mg kg−1) |
Removal Rate (%) | Concentration (mg kg−1) |
Removal Rate (%) | |
| Ctrl | 12.7 ± 0.6 a | – | 136.5 ± 19.2 a | – | 227.5 ± 0.7 a | – |
| E2 | 11.5 ± 0.4 a | −9.4 | 74.8 ± 6.5 bc | −45.2 | 181.0 ± 1.4 bc | −20.4 |
| E4 | 11.0 ± 1.4 ab | −13.4 | 99.5 ± 11.3 b | −27.1 | 203.5 ± 17.7 ab | −10.5 |
| E242 | 7.1 ± 2.5 b | −44.1 | 62.8 ± 5.1 c | −54.0 | 155.5 ± 6.4 c | −31.6 |
Values are presented as means ± standard deviation (n = 3). Different superscript letters within the same row indicate significant differences between groups (p < 0.05) determined by Duncan’s multiple range test.