Patent ID: 9045595
Filing Date: 2015-06-02
Classification: C08G,C12P

Abstract:
1. A process for recovering polyhydroxyalkanoates (PHAs) from a concentrated cellular biomass slurry of bacteria in an aqueous suspension obtained by a flocculation and concentration method comprising: providing a cellular biomass in suspension in a fermented culture medium, diluting the cellular biomass in water to form a fermented material to water ratio of up to about 1-3.0:1, acidifying the diluted cellular biomass to between pH 1.5 to about 5.5, adding an alkalizing agent to bring the pH of the biomass to between pH 7 and pH 12.0, and adding a flocculating agent to the alkalized solution to obtain flocculated biomass, the process comprising the steps of: (i) injecting PHA solvent into the concentrated cellular biomass slurry while vigorously agitating the slurry; (ii) heating the slurry in the interior of a reactor to dissolve the PHA contained in the cellular biomass and form a suspension; (iii) separating the solvent, enriched with the dissolved PHA, from the suspension; (iv) rapidly cooling the PHA solvent solution enriched with PHA to a temperature which is sufficient to substantially precipitate all the dissolved PHA; (v) cold micro filtering the solvent solution at a temperature sufficient to precipitate the dissolved PHA; (vi) separating a concentrated paste of precipitated PHA from the micro-filtered solution; (vii) washing the paste concentrated with PHA with water, while heating and agitating the paste, to promote sufficient evaporation of solvent to form a suspension containing brittle PHA granules of high porosity; (viii) agitating the washed and heated PHA granules, while injecting water vapor into the suspension containing the remaining solvent and water, wherein the recovery rate of PHA particles is 90% or greater; and (ix) separating the purified PHA particles from the suspension wherein the cellular biomass is a biomass derived from any microorganism or plant, which can produce PHA naturally or by genetic modification.