TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In method (M1): the step of filtering the biomass-derived pyrolysis oil includes forming the low-solids biomass-derived pyrolysis oil having a solids content of less than or equal to 1500 ppm, preferably less than or equal to 100 ppm; and the step of filtering the biomass-derived pyrolysis oil includes producing a pressure drop across the high flux rate filter arrangement of no more than 175 kPa, and the step of filtering the low-solids biomass-derived pyrolysis oil includes producing a pressure drop across the fine filter arrangement of no more than 175 kPa. The method (M1) further comprises heating the biomass-derived pyrolysis oil to a temperature of 30-60 degrees C prior to the step of filtering the biomass-derived pyrolysis oil. In method (M2), the step of regenerating includes: removing residual oil from the spent ion-exchange resin by washing the spent ion-exchange resin with an oxygenated ion-exchange regenerant; washing the spent ion-exchange resin with the oxygenated ion-exchange regenerant comprising ethanol, methanol, acetone and/or 2-butanone; rinsing the spent ion-exchange resin with water after the step of removing the residual oil; contacting the spent ion-exchange resin with the solution comprising aqueous sodium chloride; recharging the spent sodium-ion-containing exchange resin with an acidic ion-exchange regenerant to form the regenerated ion-exchange resin; contacting the spent sodium-ion-containing exchange resin with the acidic ion-exchange regenerant comprising aqueous sulfuric acid; and rinsing the regenerated ion-exchange resin with water prior to the step of contacting the second portion of the ultra-low-solids biomass-derived pyrolysis oil. The step of filtering includes filtering the biomass-derived pyrolysis oil with a high flux rate filter arrangement to form a low-solids biomass-derived pyrolysis oil, and filtering the low-solids biomass-derived pyrolysis oil with a fine filter arrangement to form the ultra-low-solids biomass-derived pyrolysis oil. Preferred Components: The high flux rate filter arrangement has the flux rate of 100-500 (preferably 200-500) l/m2/hour. The fine filter arrangement has the pore diameter of 5-50 mu m. EXAMPLE - No suitable example given.