Abstract: Chemical waste liquid contains organic matter but features high?alkali?metal content. Direct incineration suffers from low burnout efficiency and difficult control of pollutant emissions. Oxygen?carrier?aided oxy?fuel combustion of dried waste?liquid residues blended with biomass represents one promising new route for clean and efficient treatment of such waste liquid. The present work uses a natural low?cost hematite ore as oxygen carrier. Dried waste?liquid residues and rice husk served as blended fuels. Single?factor experiments were carried out in a fixed?bed reactor to systematically investigate the effects of reaction temperature (650–950?°C), oxygen concentration (0%–40%), and oxygen?carrier?to?fuel mass ratio (0:1, 1:1, 2:1, 3:1) on carbon conversion efficiency, carbon conversion rate, and gas?product distribution during co?combustion of dried waste?liquid residues and rice husk. XRD and SEM?EDS characterizations were performed on fresh and spent oxygen carriers to explore the evolution of phase composition, morphology and elemental distribution under different operating conditions, to reveal the mechanism for combustion enhancement. The results demonstrate that with the assistance of natural?hematite oxygen carrier, carbon conversion increases with increasing temperature, oxygen volume fraction and oxygen?carrier fraction. At an oxygen?carrier?to?fuel ratio of 1:1 and oxygen concentration of 21%, carbon conversion increases from 74.03% to 80.28% with the increasing temperature from 650?°C to 950?°C. At 950?°C, carbon conversion increases from 62.28% to 84.65% with the increasing oxygen concentration from 0% to 40%, and the most prominent improvement observed is within 0%–21% O?. The oxygen carrier greatly promotes the conversion of CO, CH? and H? and substantially improves CO? selectivity. The carbon conversion increases from 76.91% to 90.31%, and the peak carbon?conversion rate increases from 5.68×10???mol/s to 1.01×10???mol/s. Orthogonal tests indicate that the influencing order of the three factors on carbon conversion is oxygen volume fraction > oxygen?carrier?to?fuel ratio > temperature. The optimal operating condition is 950?°C, 40% O? and oxygen?carrier?to?fuel mass ratio of 3:1, yielding a carbon conversion of 90.31%. Characterizations of spent oxygen carriers reveal that Fe?O? releases lattice oxygen to oxidize CO, H?, CH? and residual carbon. Nevertheless, sodium as an alkali?metal element in dried waste?liquid residues triggers the formation of alkali aluminosilicate phases, causing particle agglomeration and deactivation of the oxygen carrier, which can be mitigated by elevating oxygen concentration. Appropriate adjustment of reaction conditions can effectively improve the co?combustion performance of waste?liquid residues and biomass, providing theoretical support for energy?oriented treatment of chemical waste liquid.