Table 1.
Total P content and P fraction concentrations in wastewater alum sludges, mineral fertilizer and organic manure
| Sludge source | Total Al (%) | Total P (%) | Total N (%) | Plant-avail. P (mg/kg) | Water-sol- P (mg/kg) | Organic P (mg/kg) | Al-bound P (mg/kg) | Reference |
|---|---|---|---|---|---|---|---|---|
| Al sulphate (thermal hydrolysis 160–165 °C), Norway | 4.34 | 3.1 | NA | NA | 26.5 | 3039 | 11850 | Krogstad et al. (2005) |
| Al agent (PAX 21), pasteurisation (65–70 ◦C), Norway | 7.17 | 2.3 | NA | NA | 6.5 | 2475 | 7400 | Krogstad et al. (2005) |
| Al sulphate, Norway (dried 40 °C) | 8.4 | 3.1 | 5.2 | 21.2* | NA | 2500 | NA | Øgaard and Brod (2016) |
| Poly Al chloride sludge, filtered and dried for 48 h at 105 °C. Ground < 0.5 mm. Korea | 16.3 | 5.6 | NA | 2100 | 22.4 | NA | 16240 | Toor et al. (2019) |
| Alum sludge, dewatered (18% soils) Manitoba, Canada | 1.1 | 1.2 | NA | 808** | NA | NA | NA | Tolofari et al. (2021) |
| Alum sludge, dewatered/stock piled-1-week in field, Australia | 7.5 | 3.7 | 5 | NA | NA | NA | NA | Rigby et al. (2013) |
| Al sulphate sludge, dried 100 °C, California, USA | NA | 1.7 | 2.7 | NA | NA | NA | NA | Gestring and Jarrell (1982) |
| DAP (fertilizer) | Nil | 15 | 18 | 100 | 100 | Nil | Nil | McLaren and Cameron (1996) |
| Cow manure | Nil | 0.2 | 0.7 | NA | Nil | ⁓2000 | Nil | McLaren and Cameron (1996) |
* CaCl2 extractable P, **bicarbonate extractable P, NA -not available