Textile industries result in the production of a large amount of wastewater with a robust and persistent color.In the textile industries,Azo dyes are primarily used,which have become harmful to the environment.Basic Red 46（BR 46）dye is an industrial dye used as a model compound for Azo dyes,which have been identified as one of the most problematic dyes in industrial effluents.This is a clear sign that Azo dye removal from wastewater,such as BR 46,is a pressing issue that must be addressed.Different methods,such as coagulation,membrane separation,adsorption and advanced oxidation,etc.,have been reported and used to treat dye wastewater,and the prospect of different procedures has been explored.Therefore,it is essential to seek a suitable process to control dye wastewater pollution.In this study,ozonation,biochar,and ultrafiltration（UF）membrane were used to treatment BR 46.The removal rates of BR 46 by ozone,biochar,UF membrane,or their combined processes were investigated,and membrane flux variation was evaluated.This study was conducted to investigate biochar samples derived from bamboo and rice straw for adsorbing Basic Red 46（BR 46）from aqueous solutions using batch experiments.Bamboo（B）and rice straw（R）were pyrolyzed at 500 and 700℃（B500,B700,R500,and R700）.Experimental data of BR 46 adsorption on B500,B700,R500,and R700 well-fitted pseudo-second-order kinetic model（R2>0.99）.After 24 hours,the dye and biochars had almost reached adsorption equilibrium,with R500 and R700 having higher adsorption efficiency than B500 and B700.The solution’s p H largely influenced the surface charge of biochars,which resulted in the variation of adsorption capacities of BR 46.With the increase of p H values,the adsorption capacities increase with a maximum occurring at a p H of 11.The adsorption isotherms indicated that the adsorption of BR 46 on B500,B700,R500,and R700 better fitted the Langmuir model than the Freundlich model.Additionally,adsorption capacity increased with an increase in temperature,which implies that adsorption is favoured at high temperatures.Furthermore,the thermodynamic analysis suggested spontaneous and feasible processes occurred for the adsorption of BR 46 on B500,B700,R500,and R700 samples.The values of the adsorption coefficient（Kd）were on the order of 102-103.Moreover,biochar-loaded Fe or Mn did not decrease the adsorption capacity of BR 46.Ozone,ozone-biochar,and ozone-biochar with catalyst used to treat dye solution indicated that the removal rates of BR 46 by ozone increased with the increasing contact time.The combined ozone and biochar process obtained higher removal rates of BR 46 than that by ozone.Especially for rice straw biochars,higher removal rates were obtained because of their high adsorption capacity.Dye removals can be increased even further when the ozonation process is enhanced with a biochar-based catalyst.The rice straw biochar pyrolyzed at 700°C with manganese（II）nitrate obtained the best dye color removal efficiency.Overall,biochar or biochar with catalyst and ozonation together had a significant impact on dye color removal.The dye solution filtrated by a single UF membrane revealed that the UF membrane removed the dye relatively poorly,resulting in a slight decrease in membrane flux.When ozone and UF membrane were used to treat BR 46,removal rates were enhanced,and the highest removal rates were obtained by ozone-PAN membrane during three membrane processes.The membrane flux decreased slightly for three UF membranes.When ozone,biochar with catalyst,and a UF membrane were used to remove the dye,the ozone-biochar-UF process yielded a higher removal rate than the ozone-biochar process.Because of the relatively large adsorption capacity of rice straw biochars,it removed the dye better than that by bamboo biochars.Significantly,the R700 with Mn had the best dye color removal efficiency.Overall,the use of biochar,ozonation,and UF membrane together significantly impacted dye color removal.For ozone-biochar with catalyst and UF processes,membrane flux was higher than that of the ozonebiochar-UF process.Overall,membrane flux for the rice straw process was higher than that of the bamboo process during ozone,biochar with catalyst,and UF membrane processes.The membrane flux results by high-temperature pyrolysis biochar were better than that by lowtemperature pyrolysis biochar,and biochar with Mn improved membrane flux better than biochar with Fe.