Take a large beaker and add 100 mL of water to it.
Add a source of cellulose to the beaker and begin stirring it with a large spoon until the liquid inside the beaker is a dark, deep green color.
Place a coffee filter inside a strainer and place the strainer over a separate beaker.
Filter off the solution from inside the first beaker to remove any grass particles. Doing so will extract the chlorophyll from the grass.
Allow the grass mulch to completely dry. With the water and chlorophyll now extracted, cellulose is the only remaining component.