FIELD: waste disposal. SUBSTANCE: invention, in particular, relates to waste water sludges formed through agency of microorganisms and containing water-retaining cell structure. pH value of sludge is lowered below 4 and sludge is subjected to heat treatment, in particular, at 126-199 C. Heat treatment time should be such as to preserve elevated filterability of sludge, and pressure should ensure liquid state of sludge. Sludge is neutralized to pH 5-9 with ionic calcium compound which may be dust from cement roasting kiln or calcium hydroxide. Then, mechanical filtration is effected, which can be preceded by repeated heat treatment at 126-199 C during the time ensuring preservation of elevated filterability of sludge even at pressure ensuring liquid state of sludge. Sludge may as well be treated in such a way that heat treatment is performed by direct contact with steam under pressure at 143-199 C for 15 min to 3 h, repeated heat treatment at 126 C for 5 min, and filtration for at least 2 h to water content in sludge below 55 wt %. EFFECT: enhanced treatment efficiency. 15 cl, 1 dwg , 12 tbl
