TECHNOLOGY FOCUS - POLYMERS - Preferred Method: In processing wood fiber fraction, the physical processing is based on kinetic energy applied to the wood fiber fraction non-uniformly in respect of time and place. Physical processing is based on strong solid and/or liquid material flows which are applied to the wood fiber fraction and which contain organic and/or inorganic microparticles and/or nanoparticles. Physical processing utilizes a ball mill, a stone mill, and/or a counter impact mill. It is based on defibrating the wood fibers in the fraction by means of mineral particles contained in the fraction and/or added to it. The mineral particles comprise calcium carbonate (CaCO3) particles. Physical processing is based on ultrasound, where ultrasound is applied to the wood fiber fraction in order to produce a gel-like pulp. The particles disclosed in the method are separated from the gel-like pulp by dissolving the pulp into a solvent and separating the liquid phase from the pulp. The biocatalyst comprises a living microbial growth and/or an enzyme produced by it when present in the fraction. It comprises a single enzyme, an enzyme mixture or a mixture of several enzyme mixtures. The biological or biochemical processing comprises the steps of adding a chosen enzyme to the wood fiber fraction prior to feeding the fraction to a counter impact mill; allowing the enzyme to work for a given period of time; and running, after the given period of time, the enzyme containing wood fiber fraction through the counter impact mill. Enzyme comprises one or more enzymes having a disintegrating influence on lignocellulose or the bonds between wood fibers. The recovered gel-like pulp contains cellulose microfibrils. It contains molecular and/or amorphous cellulose such that the recovered gel-like pulp is usable for manufacturing nanocomposites. The wood fiber fraction comprises waste sludge generated in pulp and paper industry. The wood fiber fraction comprises fibrous clay, OPA precipitate, and/or flour. Water is removed from the gel-like pulp. Water in the gel-like pulp is replaced by an organic solvent. Preferred System: In the system, the means for performing the physical processing comprise a ball mill, a stone mill, and/or a counter impact mill. The means for performing the physical processing comprise means for producing ultrasound and applying it to the wood fiber fraction in order to provide a gel-like pulp. EXAMPLE - No suitable example given.