Environmental Engineering Reference
In-Depth Information
Table 12.6 Digestate separation by decanter centrifuge: average content of total
solids, ashes, volatile solids, suspended solids and pH
Total
solids (%)
Ash
content (%)
Volatile
solids
a
(%)
Suspended
solids (mg/l)
pH
(ppm)
Input digestate
4.85
1.46
3.39
35,000
7.64
Liquid
output fraction
2.31
0.82
1.49
8,400
7.94
Solid
output fraction
27.66
6.46
21.20
Not relevant
8.12
a
Values for volatile solids are not measured but calculated as the difference
between total solids and ash content.
Source: Adapted from DANETV (2010).
Table 12.7
Digestate separation by decanter centrifuge: average concentrations
of nutrients
Total
nitrogen
(kg/t)
Ammonium
nitrogen
(kg/t)
Organic
nitrogen
a
(kg/t)
Total
phosphorus
(kg/t)
Total
sulfur
(kg/t)
Input digestate 4.08 2.87 1.21 0.94 0.42
Liquid output fraction 3.49 2.63 0.86 0.31 0.29
Solid output fraction 8.15 4.50 3.65 6.52 1.56
a
Values for organic nitrogen are not measured but calculated as the difference
between total N and ammonium N.
Source: Adapted from DANETV (2010).
Table 12.8
Example of digestate separation by decanter centrifuge
Digestate
Fiber fraction
Liquid fraction
Quantity (kg)
1000
80
920
Dry matter content 2.8% (kg)
28
24
4
Water content (kg)
972
56
916
Total N nitrogen (kg)
5
1.25
3.75
NH
4
-N (kg)
4
0.3
3.7
Phosphorus (kg)
0.9
0.7
0.2
Potassium (kg)
2.8
0.2
2.6
Source: Adapted from Jørgensen (2009).
For each batch, the weight or volume of input digested biomass, liquid
output fraction and solid output fraction was measured and concentrations
of solids and nutrients were determined by analyzing representative samples
of the inlet and the two outlet flows. During treatment of the five batches,
the decanter centrifuge treated 283m
3
of digestate, corresponding to an
average capacity of 13.72m
3
biomass treated per hour. A specific example of
the effect of digestate separation by decanter centrifuge is given in Table
12.8.
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