Table 7 Estimated potential annual accumulated mass (AM) of critical, strategic and precious elements in the sludge from the investigated WWTPs
Unit | WWTP 1 | WWTP 2 | WWTP 3 | WWTP 4 | WWTP 5 | WWTP 6 | WWTP 7 | WWTP 8 | |
|---|---|---|---|---|---|---|---|---|---|
Li | kg/year | 1.2 | 15.0 | 3.8 | – | 149.3 | 1.5 | 4.1 | 1.1 |
Cr | kg/year | 12.1 | 132.7 | 35.2 | – | 1006.5 | 13.2 | 33.6 | 17.9 |
Co | kg/year | 0.7 | 9.3 | 4.4 | – | 120.7 | 1.0 | 2.1 | 1.2 |
Al | kg/year | 1499.8 | 21,708.5 | 9034.1 | – | 299,038.0 | 2289.9 | 4885.2 | 2043.9 |
Mg | kg/year | 588.8 | 7551.4 | 3625.3 | – | 128,927.2 | 705.8 | 638.7 | 1128.0 |
Mn | kg/year | 32.9 | 455.0 | 186.4 | – | 8349.0 | 74.9 | 213.8 | 140.4 |
Ti | kg/year | 136.4 | 2610.2 | 770.5 | – | 30,469.9 | 234.6 | 364.3 | 236.6 |
V | kg/year | 4.5 | 53.7 | 43.7 | – | 736.6 | 3.6 | 10.2 | 3.1 |
Ni | kg/year | 5.0 | 61.0 | 22.0 | – | 689.0 | 7.0 | 16.1 | 8.0 |
Cu | kg/year | 19.1 | 314.5 | 102.4 | – | 6953.5 | 36.8 | 40.8 | 37.0 |
Sr | kg/year | 29.1 | 249.8 | 120.0 | – | 3626.3 | 16.5 | 20.7 | 65.6 |
B | kg/year | 6.0 | 52.2 | 14.7 | – | 476.0 | 8.7 | 10.1 | 12.6 |
Ga | kg/year | 1.7 | 16.3 | 9.7 | – | 283.7 | 5.1 | 4.1 | 4.6 |
As | kg/year | 0.8 | 12.1 | 5.0 | – | 104.5 | 1.1 | 14.5 | 1.0 |
Sb | kg/year | 0.1 | 4.0 | 1.1 | – | 70.0 | 0.3 | 8.2 | 0.3 |
Pd | kg/year | 0.1 | 1.2 | 0.6 | – | 14.6 | 0.2 | 0.3 | 0.2 |
Ag | kg/year | 0.2 | 7.3 | 2.3 | – | 120.4 | 1.5 | 0.9 | 0.7 |
Au | kg/year | 0.1 | 3.4 | 0.7 | – | 12.0 | 0.1 | 0.1 | 0.3 |