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In this study, coal flyash mixed with natural clay is used as a precursor for the fabrication of ceramic membranes by the uniaxial compaction method for the separation of kraft lignin (M.W. 10,000 g/mol). Different compositions of flyash (70–50%) and natural clay (25–45%) were used along with 5% of fixed inorganic materials for the synthesis of membranes. TGA results exhibited the high thermal stability of the membranes. FTIR analysis confirmed the presence of silica and alumina in the membrane. XRD peaks showed the crystalline nature and availability of metal oxide due to the flyash and clay material. SEM and AFM images depicted the porous nature and rough surface of the ceramic membranes. The average pore radius of the fabricated membrane increased from 12 to 30 nm with an increase in clay composition. The flux of the membrane increased from 3.54 to 4.07 × 10−6m3/m2s while increasing the clay composition. BET analysis also showed the increase of average pore radius and pore volume from 14.99 to 21.39 nm and 3.12 to 7.62 × 10−3cm3/g, respectively. The contact angle expanded from 11.8 to 21.56° which supports the impact of clay for better permeability. All the membrane compositions showed better corrosion resistance and negative zeta potential due to the major silica composition of flyash. The separation efficiency of lignin decreased from 76 to 70% with a decrease in flyash amount. The optimum composition of flyash and clay was 60:35 to achieve a better recovery (76.12%) of lignin and higher permeability (6.95 × 10−9m3/m2s kPa) of the membrane. Hence, the flyash-clay-based ultrafiltration membrane synthesized in this study can be used for the recovery of lignin biomass from biorefinery effluent.