Biodegradable wastes are decayed by microorganisms and are returned as nutrients to the soil. Biodegradable wastes consist of organic materials such as food wastes, papers, excretory products, and faeces. However, waste materials such as glass, plastic, and metal cannot be decayed by microorganisms. These wastes are called non-biodegradable wastes. Toxic wastes are also non-biodegradable wastes.
