Study On Decontamination Of Bleaching Effluent By White-bot Fungi

In recent years, some attention has been paid to the research on the biobleaching and biotreatment of effluent in which pulping chemistry and biotechnology are involved. White-rot fungi, which can decay wood to white, are among the most active lignolytic microorganism. Wood-degrading White-rot fungi which can secrete several extracellular enzymes, such as ligninase, manganese peroxidase, laccase and other phenol-oxidizing enzymes, are capable of completely degrading and metabolizing lignin, modified lignin and its derivatives. So white-rot fungi can decolorize and dechlor of bleach effluent, environmental pollution is reduced. This paper is the project of Tianjin Science Found Project (The Contract No.9736064 1 1): study on effluent contained high consistency of chlorinated organic compound treated by biochemical methods. The reseach contents include screening and purifing white-rot fungi; bleaching effluent treated by white-rot fungi; soda wheat pulp bleaching pretreated by white-rot fungus. 12 fungi which showed color-zone in the guaiacols medium were obtained from the nature by isolation and purification for several times. The ratio of the diameter of mycelium and that of colored zone was less than one. 12 fungi were inoculated in the medium which contained eucalyptu wood powder and minerals, and incubated at 39 慍 for 15 days. The Selection Factors were determined, Two strains( Fl, F7)had high capacity for deligification and SF values were 3.08 and 2.70 respectively. 12 fungi were inoculated in the bleaching effluent medium which was added with 2~.4-bichlorophenol, and incubated at 39擟 for 7 days. Two strains (P7, F9) had high capacity for bio-degradation of 2~ 4-bichlorophenol .The rates of degradation were 87.58% and 89.65% 3 respectively. 2 white-rot fungi(F7, F9) which have high ability to decolorize combined wheat straw soda pulp bleaching effluent (CE stage) have been screened. Treating?the same effluent with those fungi and Phanerochaete Chrysosporium after 4 days, decolorization of F7, F9 and Phanerochaete Chysosporium were 74.11%, 46.67%, 62.22% respectively. After cultivation for eight days, F7 showed no remarkable decolorization, but F9 resulted in 67.58% decolorization. In comparison, the fungus F7 showed higher activity in the decolorization of the effluent. Carbon & nitrogen sources, Mn2~ and p1-1 are important for bleaching effluent decolorization by fungus F7. The results showed that the optimum culture conditions contained the following: P (glucose) lOg/L, p (NI-14C1) O.13g/L, iJ (Mn2D 2Omg/L. As ~ (glucose), P (NH4CI) increased, there was a corresponding increase in the biomass. The high concentration of NH4CI would repress the decolorization of effluent by fungus F7. The suitable conditions for fungal growth was at pH4挆5 and that of fungal decolorization was at pH 3-6. The optimum culture conditions for decolorization was at pH 5. The toxicity could be eliminated after effluent treated with white-rot fungus. Most GC peaks of pollutant in bleach effluent decrease after treatment by fungus F7. The paper presented Volterra kinetics models for describing mycelial weight and decolorization for bleaching effluent treated by white-rot fungus F7, simulated results showed that Volterra kinetics models can well describe the process. The pathway of reaction betw...