Table 2. Characteristics of sludges in each experiment.

Experiment
I
II
III

Characteristic

Initial

Final

Initial

Final
Initial

Final

pH

7.2

7.3

7.5

7.1

7.4

7.0

TSS (g L-1)

37.9

--

46.4

39.2

56.3

36.7

FSS (g L-1)

14.2

--

17.2

22.6

28.5

14.5

VSS (g L-1)

23.7

--

29.2

16.6

27.8

22.2

COD (g L-1)

51.8

36.6

32.9

25.9

65.7

36.3

Protein (g L-1)

18.7

14.0

9.8

7.1

13.5

9.9

Alkalinity (mg CaCO3 L-1)

508

1,076

442

762

781

1,171

Volatile Acid (mg CH3COOH L-1)

126

210

109

118

130

188

Humidity (% w/w)

93

91

95

91

92

90

Total Organic Carbon (% w/w)

33

19

35

30

30

32

Total Organic Matter (% w/w)
59
59
63
54
54
57
             

Cu (g Kg-1)

0.4

0.4

0.3

0.3

0.3

0.3

Zn (g Kg-1)
1.8
1.7
2.0
2.2
0.4
0.6
Fe (g Kg-1)
39.0
34.7
48.7
54.4
63.3
61.6
Cr (g Kg-1)
0.1
0.1
0.1
0.1
0.04
0.03
             
Nitrogen (Kjeldahl) (% w/w)
3.5
3.2
3.6
3.4
3.3
3.1
C/N
9.3
10.1
9.6
8.9
9.2
10.1
P (g Kg-1)
8.1
7.6
6.7
7.0
7.1
7.0
K (g Kg-1)
1.0
1.0
1.3
1.0
1.0
1.2
Ca (g Kg-1)
20.6
22.4
15.5
14.7
21.0
17.2
Mg (g Kg-1)
4.1
4.6
3.0
2.9
3.7
3.1
Mn (g Kg-1)
0.2
0.2
0.6
0.6
0.3
0.3


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