 If the biodegradable starting material contains nitrogen, phosphorus and sulfur, then the end products may also include their oxidised forms- nitrate, phosphate and sulfate.In an aerobic system the majority of the energy in the starting material is released as heat by their oxidisation into carbon dioxide and water.Composting systems typically include organisms such as fungi that are able to break down lignin and celluloses to a greater extent than anaerobic bacteria.