the perforations are sized to retain the wood pulp between intermediate and internal passageways 40 and 42 while admitting oxygen into the wood pulp the oxygen is introduced as an oxygen containing gas into gas inlet 48 of body portion 36 the oxygen containing gas passes into external passageway 38 through the perforations of intermediate passageway 40 and then into the wood pulp the oxygen containing gas travels in an inward radial direction of the passageways to internal passageway 42 excess oxygen containing gas not reacted with the wood pulp is then discharged from a gas outlet 50 of body portion 36 in communication with internal passageway 42 it is understood that reactor 28 as described above if appropriately sized could serve other purposes for instance a wood pulp mixer in accordance with the present invention could be used to mix steam with the wood pulp or in place of a static mixer to mix a gas with wood pulp in order to conserve oxygen in apparatus 10 oxygen containing gas is pumped from gas outlet 50 back into gas outlet 48 for recycling back into the wood pulp this is effectuated by means of an eductor 60 eductor 60 has a low pressure inlet 62 and a high pressure inlet 64 high pressure motive fluid pumped through high pressure inlet 64 creates a low pressure region in eductor 60 to draw the oxygen containing gas and entrain it with the motive fluid being pumped through inlet.