Abstract: There is provided an apparatus in which a distribution head 6 is arranged in a sludge pipe 1, through which a wastewater or sewage sludge stream 2 flows, is associated with a rotational plane 18 and includes flocculation liquid outlets (10) and mixing blades (11). It is desirable to provide for a better admixing of the flocculant liquid to the wastewater or sewage sludge. This is achieved by forming the flocculant liquid outlets 10 as slots and the mixing blades 11 as strips which extend transverse to the rotational plane 18 and have a length equal to at least half of the width of the sludge stream. The flocculant liquid exits from each slot as a broad strip into which a following blade extends and pulls along its outer edge the flocculant liquid in a form of a foggy strip through the wastewater or sewage sludge. The water content of the flocculant liquid should be such that maximum 3 parts of the flocculant liquid is admixed to 100 parts of the wastewater or sewage sludge.