Table 2. Variation of strength of composite heavy metals (Cd, Zn, Ni and Cu).
| Composite heavy metals | Details |
|---|---|
| 8 | Contain 2 mg/l of each metal |
| 20 | Contain 5 mg/l of each metal |
| 28 | Contain 7 mg/l of each metal |
| 40 | Contain 10 mg/l of each metal |
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