is positioned within container 130 adjacent to floor 132 and is constructed out of a sturdy perforated material preferably each drain cavity 166 is positioned at the lowest section of container 130 a drain 150 extends through floor 132 at each drain cavity 166 each drain 150 may be connected to manifold line 151 manifold drain line 151 is typically connected at drains 150 and includes a valve 153 for controlled release of sludge liquids for transmittal for disposal or further processing drains 150 may be alternatively located in sidewalls 131 or rear wall 136 as desired a plurality of drains 150 may be provided for each drain cavity 166 a plurality of manifold drain lines 151 may be provided in the embodiment of fig5 filter media 24 and net 26 are depicted arranged along sidewalls 131 and rear wall 136 sludge liquids not shown migrate horizontally and vertically intermediate filter media 24 and sidewalls 131 and rear wall 136 as previously described herein a drain cavity may be provided along rear wall 136 however a drain cavity is not required if the sludge filter 10 positioned on rear wall 136 is in fluid communication with drain cavities 166 alternatively the sludge filter 10 may be disposed only along sidewalls 131 as in the embodiment of fig1 2 and 3 sludge filter 10 is removably attached to container 130 by a two part fastener system 28 extending around the perimeter of the sludge filter 10 with first fastener portion 27.