Research Article
Recovery of Bacillus licheniformis Alkaline Protease from Supernatant of Fermented Wastewater Sludge Using Ultrafiltration and Its Characterization
Table 1
Physical and chemical characteristics of secondary sludge.
| Characteristics | Concentration |
| Physical characteristics: | | Total solids (g/L) | 29 ± 1.2 | Volatile solids (g/L) | 18 ± 0.6 | Suspended solids (g/L) | 22 ± 0.9 | Volatile suspended solids (g/L) | 17 ± 0.7 | pH | 5.7 ± 0.3 |
| Chemical characteristics: | | Total carbon (%, dry total solids) | 38.12 ± 1.5 | Total nitrogen (%, dry total solids) | 5.5 ± 0.3 | Ammonical nitrogen (mg N/kg) | 680 ± 22.1 | Total phosphorus (mg P/kg) | 12 422 ± 42 | Orthophosphates (mg P/kg) | 7 780 ± 24 |
| Metals (in mg/kg) (dry basis): | | Al3+ | 13 305 ± 41 | Ca2+ | 16 160 ± 45 | Cd2+ | 3.5 ± 0.16 | Cr3+ | 66.5 ± 2 | Cu2+ | 270 ± 9 | Fe2+ | 10 365 ± 30 | Mg2+ | 1874 ± 62 | Mn2+ | 198 ± 6.9 | K+ | 1720 ± 53 | Pb2+ | 61 ± 2 | Zn2+ | 477 ± 15 |
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