Table 4 Average, minimum and maximum values of the macro- and microelement content in mg per kg of sludge DW from all studied WWTP

Macroelements

 Average

37,408 ± 4115

18,268 ± 5419

6678 ± 2741

6323 ± 1130

34,583 ± 8274

 Min

20,593 ± 2265

10,663 ± 521

3147 ± 126

4730 ± 198

16,693 ± 801

 Max

60,031 ± 6603

26,726 ± 1098

12,407 ± 606

8102 ± 315

43,310 ± 2122

 Median

37,564

18,811

6176

5958

37,606

 % DW

2.1% to 6%

1.5% to 2.7%

0.5% to 0.8%

 Range in literature^a

3.40% to 9.76%

1.06% to 3.8%

0.2% to 0.5%

Microelements

 Average

47 ± 15

690 ± 451

33,386 ± 6780

51 ± 12

239 ± 82

1419 ± 699

9.2 ± 1.4

 Min

28 ± 1

346 ± 22

22,792 ± 915

42 ± 2

188 ± 9

546 ± 35

7.6 ± 0.2

 Max

69 ± 3

1625 ± 103

42,633 ± 1833

79 ± 5

434 ± 21

2688 ± 116

11.7 ± 0.5

 Median

45.5

505

33,909

47

201.5

1241

9.0