ABSTRACT
In view of stabilization of sludges at small treatment plants, the effective sludge stabilization processes can be tabulated (Table 6.1) as under: Effective sludge stabilization processes
S.No.
Process
Process Description
1.
Sludge pasteurization
Minimum mean retention (MMR) of 30 min at 70 °C or 4 h at 55 °C followed by mesophilic anaerobic digestion.
2.
Mesophilic anaerobic digestion
Minimum mean retention (MMR) of 12 d at temperature of 35 ± 3 °C followed by MMR of 14 d secondary storage.
3.
Thermophilic aerobic digestion
Minimum mean retention of 7 d with a minimum of 4 h at 55 °C or higher.
4.
Composting
Minimum mean retention (MMR) of 40 °C for 5 d including 4 h at minimum of 55 °C followed by minimum of 2 months maturation.
5.
Lime stabilization
pH not less than 12 for minimum of 2 h.
6.
Lime conditioning, dewatering and storage
Minimum storage period of 3 months.
7.
Dewatering storage
Minimum storage period of 6 months.
8.
Liquid storage
Minimum storage period of 3 months.
