Enzymatic treatment method and system for fibrous cellulosic material and rigid cellulosic product, wherein the method comprises introduction of raw fibrous cellulosic material (1) in a stirrer (20); enzymatic treatment of the raw fibrous cellulosic material (1) for a specific period of time to obtain a treated cellulosic material, said enzymatic treatment including the addition of enzymes (11, 12, 13, 14) to the raw fibrous cellulosic material and the uniform distribution of said enzymes in the raw fibrous cellulosic material by stirring; drying the treated cellulosic material; wherein at least a proportion of the raw fibrous cellulosic material is derived from industrial waste.