combined arithmetic and geometric spacing for the extraction rollers is arithmetic progression 20 24 24 24 24 geometric progression 19 1 17 3 14 8 11 3 the formula for the geometric spacing is in the form in aligning upper frame 14 for support on lower frame 12 the pressure rollers 38 through 43 on the upper frame are not immediately above the extraction rollers 28 through 34 on the lower frame 12 but are positioned between extraction rollers 28 through 34 such that roller 38 is positioned between rollers 29 and 30 roller 40 is positioned between rollers 30 and 31 and so on until roller 43 is positioned between rollers 33 and 34 it can be seen that lower conveying rollers 35 36 and 37 carry sludge material to be extracted to the area of the offset rollers and their respective belts 44 and 58 it is further contemplated that by using the arithmetic progressive spacing the rollers and the fact that the upper and lower rollers are offset from one another that a continually increasing pressure and extractive pressure is exerted to the sludge material the endless pervious belt 44 is preferably made of a woven polyester nylon metal or a combination of the preceding materials with opening sizes varying from 10 to 2000 microns however the preferred material used in the construction of the pervious belt is a woven polyester the endless pervious belt 44 is drawn by drive extraction rollers 28 29 and 30.