A Pharmaceutical customer’s standard operating procedure required a process to use powdered carbon to de-colourise an active pharmaceutical derivative. This carbon was then removed from the process using a plate and frame filter fol-lowed by a cartridge type guard filter. Several batch failures had been experienced due to by-pass on the filter press and John Morfield Ltd was asked to review the filtration system and propose remedial action.
During a site audit it was established that it was possible to incorrectly fit the seals due to the nature of the construction of the press. Seal leak-age allowed bypass of carbon which then led to batch failure. The remedy was to either re-tighten the seals in position or as in most cases to re-dress the press which involved removing it to a wash bay area for cleaning and fitting of new filter cloths. The product would then be held in the reactor vessel during this re-dressing process which also gave some cause for concern due to possible product degradation.
John Morfield recommended that a new filter system using 3MCuno Zeta Plus filters be used to replace the filter press. Zeta plus is a family of depth filtration media composed of filter aids embedded in a cellulose matrix The media is in the form of Lenticular cartridges that are held in a dedicated filter housing. The number of lenticles and cartridges per housing may be optimised to accommodate the quantity of carbon to be retained.
Lab scale trials were carried out by 3mCuno SASS services to establish the grade of Zeta plus to be used .The chosen grade of filter in the form of a 47mm disc was then used to success-fully process the trial batch and it was calculated by scaling up to full production volume that two zeta plus 16”, 9 cell cartridges would be needed to remove the carbon from each process batch. Plant trials were conducted by engineering a retrofit package to fit two Zeta plus cartridges into the filter press and the trials successfully proved the ability of the two cartridges to re-move the carbon from the process batch. The decision was then made to replace the press with two dedicated Zeta plus filter housings
The benefits of the new filtration skid are: to guarantee the filter process as being leak free resulting in elimination of batch failures, allow quicker filter changes with less manpower being needed, contribute to a significantly cleaner process and shorter clean down times with a reduction in waste disposal costs. One further benefit was the potential to reduce operational transfer times thereby reducing the risk of product degradation.