separator s can be operated at pressures between about 0 psig to about 200 psig the solid liquid separator in the solid liquid displacement zone 40 may be operated in continuous or batch mode although it will be appreciated that for commercial processes the continuous mode is preferred the impurities are displaced from the solid liquid displacement zone 40 into a mother liquor stream and withdrawn via line 60 in one embodiment of the invention additional solvent is fed to the solid liquid displacement zone 40 via line 50 to reslurry the carboxylic acid slurry 30 and form a slurry or cake carboxylic acid product 70 when a terephthalic acid slurry is utilized in the solid liquid separation zone 40 a slurry or cake terephthalic acid product is produced the slurry or cake terephthalic acid product typically comprises terephthalic acid and acetic acid the mother liquor 60 is withdrawn from solid liquid displacement zone 40 via line 60 and comprises a solvent typically acetic acid catalyst and bromine compounds the mother liquor in line 60 may either be sent to a process for separating impurities from oxidation solvent via lines not shown or recycled to the catalyst system via lines not shown one technique for impurity removal from the mother liquor 60 commonly used in the chemical processing industry is to draw out or u201c purge u201d some portion of the recycle stream typically the purge stream is simply disposed of or if economically justified subjected to various treatments to remove undesired impurities while recovering valuable components examples of impurity removal processes include u s pat no 4 939 297 and u s pat no 4 356 319 herein incorporated by reference step b comprises removing in a solvent.