The paper presents the results of experimental studies on the mechanical dewatering of combined sludge generated during the industrial wastewater treatment of steel mill. The technological parameters of the sludge mechanical dewatering of combined sludge have been established: anionic flocculant Praestol 2530 dose of 0.5 g/kg dry solids; the sludge dry solids loading to the plate-and-frame filter press is 4.5-5.0 g/(h ⋅ m2).