To make homemade and biodegradable cat litter, shred a newspaper pages, wet them with warm water and add a little biodegradable detergent. Let the paper soak so it acquires consistency. Then, using a strainer, wring out the wet paper. Soak again a second time, but only using warm water, and drain again with the strainer. Over the wet newspaper, sprinkle some Bicarbonate of Soda, and knead the mixture with your hands, wring out the water well. Finally, let it dry for a day on a flat surface to get the mixture to harden. Once dry, fill the box with 2-3 cm and change weekly to keep the cat litter tray clean.