Waste conversion by liquid thermophilic aerobic digestion

An aerobic batch process for the conversion of organic solid waste material by liquid thermophilic and solely aerobic digestion, comprising the steps of:

• comminuting a batch of the organic solid waste material:
• adjusting the moisture content of the comminuted material to at least 90% parts by weight of water;
• mixing the comminuted waste material with a thermophilic aerobic micro-organism;
• adjusting the pH of the mixture to 5.5-7.5;
• supplying heat and oxygen to the mixture to effect thermophilic and solely aerobic digestion of the mixture;
• testing the mixture during the aerobic digestion to detect when the mixture has reached a stabilized state in which available organic material and nutrients in the mixture have been consumed by the micro-organisms and in which the micro-organisms have not started to consume lignin or cellulose to any substantial extent;
• the testing comprising measuring at least one of the pH level, the phosphate content, the nitrate content, the sulphate content and the carbon-to-nitrogen ratio of the mixture;
• terminating the thermophilic and solely aerobic digestion process when the stabilized state is detected;
• and
• subsequently drying the mixture.