Table 1.
Physical and chemical process parameters of the pilot AD reactor prior to samplings for DNA extraction during the mesophilic and thermophilc test runs
| Mesophilic Low load, M1 | Mesophilic High load, M2 | Thermophilic Low load, M3 | Thermophilic High load, M4 | |
|---|---|---|---|---|
|
Process parameters |
|
|
|
|
| OLR*), kgVS m-3d-1 |
3 |
8 |
3 |
8-10 |
| HRT **), days |
22 |
10 |
23 |
9 |
| Temperature, °C |
36-37 |
36-37 |
54-55 |
54-55 |
| pH |
7.4-7.5 |
7.4-7.5 |
8.0-8.1 |
8.0-8.1 |
| NH4-N, g liter-1 |
1.1-1.2 |
1.2-1.3 |
1.6-1.7 |
1.0-1.1 |
| Alkalinity, mgCaCO3 liter-1 |
5400 - 6000 |
6300 - 6700 |
6200 - 6700 |
4900 - 5300 |
| VFA***), mg liter-1 |
110 - 160 |
200 - 340 |
480 - 590 |
350 - 600 |
| TS, % |
3.1 – 3.2 |
4 – 4.5 |
3.2 – 3.3 |
3.7 – 4.2 |
| VS, % |
1.6 – 1.8 |
2.4 – 2.9 |
2.0 – 2.1 |
2.3 – 2.7 |
| TS-reduction ****), % |
61 - 62 |
60 - 62 |
60 - 62 |
55 – 60 |
| VS-reduction, % |
72 - 74 |
66 - 69 |
70 - 71 |
64 - 70 |
|
Feed characteristics |
|
|
|
|
| TS, % |
|
|
|
|
| Biowaste (BW) |
14.9 – 24.6 |
29 – 32.2 |
26.7 |
29.9 – 21.1 |
| Sewage sludge (SS) |
4.1 – 4.2 |
3.1 – 4.8 |
3.3 – 4.1 |
4.5 – 6.0 |
| BW and SS mixture |
8.6 – 10.3 |
11.8 – 13.0 |
10.7 – 10.9 |
9.5 – 10.6 |
| VS, % |
|
|
|
|
| Biowaste (BW) |
14.3 – 21.6 |
21.8 – 26.2 |
24.6 |
18 – 19.1 |
| Sewage sludge (SS) |
2.7 – 3.6 |
1.8 – 3.2 |
1.9 – 2.6 |
2.8 – 3.7 |
| BW and SS mixture | 6.2 – 8.4 | 7.9 – 8.8 | 8.7 – 9.2 | 7.4 – 8.0 |
*) OLR, Organic Loading Rate. For load increase steps and times, see Figure 1.
**) HRT, Hydraulic Retention Time.
***) VFA, total Volatile Fatty Acids.
****) Reduction = [(TSfeed,in-TSdigestate, out)/TSfeed,in] x 100%.