Which of the following is incorrect regarding sludge digestion?
1
Digestion period for thermophilic digestion is 30 days
2
The desired range of pH value for efficient digestion is 6.8 to 7.2
3
Digestion destroys pathogenic bacteria
4
Carbon, Oxygen, Hydrogen, Nitrogen, Sulphur, and Phosphorous are the important nutrients required for bacterial growth in sludge