NOVELTY - Method for preparing filtrates suitable for downstream purification with minimal discharge of effluent using microbial high cell density fermentation (HDMF) broth and recombinant broth filiations involves, preparing pre-coat solution in pre-coat tank, feeding microbial HDMF and recombinant or otherwise broth containing biomass and liquid products, displacing filter vessel holdup/heel as well as entrapped liquid in the biomass wet cake, deactivating biomass in filter vessel after dewatering, rotating filter stack, and squeezing wet cake for disposal.    USE - The method is useful for preparing filtrates suitable for downstream purification with minimal discharge of effluent using microbial HDMF broth and recombinant broth filiations and for isolating and purifying biological products e.g. recombinant products.    ADVANTAGE - The method is simple, reliable and cost-effective, eliminate the requirement for centrifuging huge amount of high purity water for dilution, and reduces electricity consumption.    DETAILED DESCRIPTION - Method for preparing filtrates suitable for downstream purification with minimal discharge of effluent using microbial high cell density fermentation (HDMF) broth and recombinant broth filiations involves, (a) preparing a pre-coat solution in a pre-coat tank by mixing an inert pre-coat powder in a carrier liquid/water with the aid of an inert gas followed by circulating pre-coat solution by pumping over rotary leaf filter to achieve pre-coated filter-stack with desired thickness, (b) feeding the microbial HDMF and recombinant or otherwise broth containing biomass and liquid products, to the filter vessel through inlet nozzle under pressure through the pre-coat layer, simultaneous deposition of the moist biomass on the pre-coated filter screen to get filtered and passing out through filtrate outlet nozzle, (c) displacing the filter vessel holdup/heel as well as the entrapped liquid in the biomass wet cake by slow introduction of clean dry compressed air/nitrogen and transferring back the same to feed tank or filtered through the guard filter, (d) deactivating the biomass in the filter vessel after dewatering, (e) rotating the filter stack after deactivation to dislodge the wet cake followed by cleaning the filters using spray header and rotating filter stack for next batch and (f) squeezing Wet cake for disposal. An INDEPENDENT CLAIM is included for microbial HDMF and recombinant filtration system, which comprises (a) rotary leaf filter with filter plate stack for filtering broth after pre-coating, mounted on central shaft together with geared motor, for dislodging spent wet-biomass slurry after dewatering under air pressure and deactivation, mounted on trolley with cleaning-in-place (CIP) and sterilization-in-place (SIP) facility, (b) control panel with variable frequency drive to facilitate rotation, (c) pre-coat tank with compressed air connection for proper mixing of pre-coat in water, (d) centrifugal pump to circulate the chemically inert pre-coat slurry over the metallic filter plates until all pre-coat powder is held on filter plates and clear water, free of pre-coat powder is seen during circulation, (e) diaphragm pump to feed HDMF broth or otherwise having dissolved liquid products to rotary leaf filter through inlet nozzle to get filtered liquid through outlet nozzle, (f) guard filter to prevent accidental leakage of unfiltered turbid liquid into filtrate tank, (g) filtrate outlet of rotary leaf filter connected to inlet on guard filter to receive clear filtrate, the clear filtrate travels to filtrate storage tank, and (h) interconnecting piping, valves, instruments, CIP/SIP provision, and control panel provided for the entire system with tri-clover fittings for quick assembly and dismantling, and (i) optionally a wet cake squeezer to squeeze slurried biomass for disposal can be provided particularly for large biomass quantities.