Kitchen waste is defined as left-over organic matter from restaurants, hotels and households. Tons of kitchen wastes are produced daily in highly populated areas. Kitchen wastes entering the mixed-municipal waste system are difficult to process by standard means, such as incineration, due to the high moisture content. Furthermore, organic matter can be transformed into useful fertilizer and biofuel. New disposal methods that are both environmentally and economically efficient are being developed which rely on various forms of microbial decomposition.
The ingredients of kitchen waste are complex, mainly including rice, flour food residues, vegetables, animal and vegetable oils, meat and bone, etc. From the chemical composition, there are starch, cellulose, protein, lipids and inorganic salts.