Study On Cyclic Treatment Technology Of Dyes Using White Rot Fungus-rice Straw System

Using triphenylmethane dyes as research object, the adsorptive characteristics and affecting factors of these dyes by dead white rot fungus and rice straw were investigated in open system. Furthermore, the affecting factors and degradation characteristics of dyes by white rot fungus culturing with rice straw, the biological attribute of white rot fungus and the affecting factors and regeneration characteristics of rice straw using white rot fungus were also studied in this paper. Base on these works, the treatment technology of dyes by white rot fungus-rice straw system, using the characteristics of adsorptive removal and co-degradation of the system, was established. For industrial treatment of dye effluent, the technology has some theoretical and practical significance.The adsorptive characteristics and affecting factors of dyes by dead white rot fungus and rice straw were studied. The results showed that higher adsorption capacity of white rot fungi to anthraquinone and triphenylmethane dyes could be obtained, however, lower adsorption capacity appeared in other types of dyes. The bio-sorption of dead white rot fungus could be significantly influenced by biomass, concentration of dye and particle size, except rotation rate. When the dyes was adsorbed by rice straw, the bio-sorption of malachite green and crystal violet by rice straw could reach up to 31.89mg/g and 69.13mg/g respectively after 1h under the optimal conditions with grain diameter over 20 meshes, amount of 0.1g, and incubation at 25℃, 150r/min, pH 7. These results suggested that white rot fungus-rice straw system could transfer dyes from liquid phase system to solid phase system effectively.After malachite green and crystal violet at the concentration of 150mg/L were adsorbed by r ice straw for 1h in open system, using the degradation characteristics of the white rot fungus which could degrade rice straw and dyes, the self-generation process of white rot fungus-rice straw system was investigated. The adsorbed dyes could be degraded effectively by the white rot fungus, the degradation rate of malachite green and crystal violet could achieve 93.67% and 80% respectively after 6 days in the open system. In addition, a comparative research on the adsorption capacity of white rot fungus-rice straw system and rice straw untreated by white rot fungus was carried out, the results showed that different factors, such as time, biomass, dye concentration and pH value, didn't cause much difference, namely the regenerated white rot fungus-rice straw system could adsorbed the dyes again. Furthermore, cycling regenerated white rot fungus-rice straw system could also adsorbed dyes effectively. If the system was regenerated per 2 days, the sorption amount of the system and the decolorization rate of the dyes could still reach up to 13mg/g and 95% respectively after 5 cycles. These results suggested that the adsorption capacity of the system could be regenerated by utilizing co-degradation function of white rot fungus.The treatment of simulative dye wastewater with the technology of"adsorption-self-regeneration-adsorption"was investigated in the reactor. Similar results could be obtained in the reactor as shake-flask. Rice straw was used to adsorb malachite green and crystal violet in the reactor for 1h, the decolorization rate of the two dyes could reach up to 97% and 80% respectively. The treatment methods of rice straw had great influence on the decoloration rate. Compared to the one time adsorption, secondary adsorption had higher efficiency. For example, rice straw (1.2 g ) was used to adsorb simulative dye wastewater (600mL) with 100mg/L for 1h, the decolorization rate was 77.74% by on time adsorption, however, the decoloration rate could reach up to 85.40% by secondary adsorption. If secondary adsorption treatment method was used, the shorter time interval was, the higher of decolorization rate was in equal times. Additionally, the dye bio-sorption of cycling regenerated white rot fungus-rice straw system was further studied, the results showed that the dye bio-sorption amount of white rot fungus-rice straw system could reach up to 37mg/g after the system was regenerated for 5 times. In summary, compared to one time adsorption, secondary adsorption showed better potential in treating dye wastewater using rice straw or white rot fungus-rice straw system. The model using white rot fungus-rice straw system to treat dye wastewater was proved to be feasible.