Table 2.
Data arising from the samples analysis of the most potential locations regarding the struvite formation within the operational system of Budds Farm WWTP. The locations that present the symbol ∗ or ∗∗ indicate locations with the same sludge characteristics due to operational design. In addition, the brackets indicate the dilution of wastewater samples: double-distilled deionised water in order to reach the detection limits.
| Hot-spots of struvite precipitation | pH | T (oC) | PO43−(mg/L) | NH4+ (mg/L) | Mg2+ (mg/L) |
|---|---|---|---|---|---|
| Screened sludge storage tank | 6.5 | 20.8 | 100 (1:4) | 400 | 390 |
| Thickened sludge storage tank∗ | 5.4 | 20.8 | 100 (1:4) | 100 | 390 |
| SAS storage tank | 7.2 | 21.1 | 100 | 10 | 350 |
| Blended cake | 6.4 | 22.0 | 100 | 100 | 190 |
| Digester feed∗ | 5.9 | 20.8 | 100 | 100 | 390 |
| Digester recirculation pump | 8.4 | 21.2 | 40 | 100 | 150 |
| PDST (digested sludge) ∗∗ | 8.4 | 20.8 | 200 (1:4) | 200 (1:4) | 190 |
| Centrifuge feed∗∗ | 8.4 | 20.8 | 200 | 200 | 190 |
| SAS filtrate | 7.1 | 20.3 | 100 (1:4) | 10 | 380 (1:4) |
| Primary thickening filtrate | 5.6 | 20.7 | 200 (1:4) | 50 | 340 |
| Centrate | 8.1 | 21.5 | 40 | 200 (1:4) | 230 |
| SAS after thickened | 7.0 | 20.5 | 100 | 10 | 260 |