Sludge is treated with a motive to reduce the amount of organic matter and the microorganism which are the causative agents of many diseases. Sludge can be treated following processes:
Anaerobic digestion
This is a bacterial process carried out in the absence of oxygen. There are two methods used in this process - Thermophilic digestion or Mesophilic digestion. In thermophilic digestion fermentation of sludge takes place in tanks at a temperature of 55°C whereas in mesophilic digestion fermentation takes place at a temperature of around 36°C. The process generates biogas that is used not only for heating the tanks but also to generate electricity.
Aerobic digestion
Aerobic digestion takes place in the presence of oxygen. Organic matter is consumed by bacteria and convert it into carbon dioxide. The lack of organic matter leads to the death of bacteria. Once the bacteria dies they are used as food by other bacteria. Thus through this process solid reduction takes place. The cost of aerobic digestion is low with compared to anaerobic digestion as it consumes bacteria faster.
