Table 2.
The average numbers of microorganism indicators—somatic coliphages (SOMPCH) and most probable number (MPN) of Salmonella—before and after mesophilic/thermophilic fermentation process (mean values ± standard deviation)
| Sample (% volume in the reactor) | SOMPCH (pfu/g dry weight) | Salmonella (MPN/g dry weight) | ||||
|---|---|---|---|---|---|---|
| Start of the process | End of the mesophilic process | End of the thermophilic process | Start of the process | End of the mesophilic process | End of the thermophilic process | |
| 70 %WAS + 30 %DS (only MAD) | (4.16 ± 0.15)∙105 | (1.63 ± 0.18)∙104 | – | >11 | 11 | – |
| 40 %WAS + 30 %DS + 30 %WASD (only MAD) | (9.16 ± 0.21)∙104 | (7.76 ± 0.24)∙103 | – | 11 | 2.9 | – |
| 40 %WAS + 30 %DS + 30 %WASD (5 days MAD + 19 days TAD) | (5.23 ± 0.19)∙104 | 0 | 2.1 | 0 | ||
| 40 %WAS + 30 %DS + 30 %WASD (7 days MAD + 17 days TAD) | (4.11 ± 0.23)∙104 | 0 | 2.1 | 0 | ||
| 40 %WAS + 30 %DS + 30 %WASD (9 days MAD + 15 days TAD) | (3.48 ± 0.17)∙104 | 0 | 1.5 | 0 | ||
“%” volume of sludge, WAS waste-activated sludge, DS digested sludge, WASD WAS after hybrid disintegration, MAD mesophilic anaerobic digestion, TAD thermophilic anaerobic digestion, pfu plaque-forming unit