Paper is added to a compost pile and immediately physical changes start happening to break down the paper into smaller particles. A group of organisms or bugs called Mesofauna, like worms, ants and bettles start chewing and eating the paper causing the paper to disintegrate. This process continues as the second stage starts working at the same time.
Paper is a wood product and as the particles decrease in size from the mechanical breakdown, biological changes such as bacteria feeding on the starches of the paper. The cellulose and pectin are digested and then fungi will break down the lignins and waxes so that the paper is now unrecognizable. Carbon levels are decreased and the nitrogen levels are raised during the process.
The processes that have been going on during the composting now have prepared what was paper into now a chemically changed mass. It should now be about 50 percent mineralized and the rest turned into humic matter after giving off carbon dioxide and water. Many complex chemical reactions have happened during the whole composting of the paper until the end product is inert and ready to be used as a soil amendment.