The drum of Decker Thickner is installed eccentric to the vat radius, with more clearance on the feed side than on the discharge side. The drum rotates in the direction of the incoming feed, carrying the pulp underneath the drum to a compaction zone on the other side where dewatering occurs. Filtrate passes through the perforated deck and is discharged through the open end of the drum and an outlet connection on the vat head. The liquid level inside the drum is lower than the level in the vat outside the drum, creating a static pressure differential that drives filtration. Pulp discharge consistency can be regulated by removing or adding stainless steel weirs to the overflow wall between the filter vat and the pulp discharge box. By regulating the same, Pulp is being made thicken for easy storage in chest.