Experimental Study On Ligniase Activity Of White Rot Fungi For Dye Decolorization Under Exterior Regulations

Since 1980's, white rot fungi especially Phanerochaete chrysosporium has been applied in treatment of degradating refractory industrial wastewater such as pesticide wastewater, oil wastewater, ammunition wastewater, paper-making wastewater. Lignin peroxidase (LiP), manganese peroxidase (MnP) and Laccase (Lac) are the key enzymes in the system. Environmental conditions and exterior regulations have great effect on synthesis and activity of the key enzymes of white rot fungi, and they affect degradating efficiency of pollutants.In this thesis, Phanerochaete chrysosporium is applied to treat with the dye wastewater under exterior regulations in the types and concentrations of nutritions, inducements and dyes. These influence the change of MnP activity and the effect of wastewater treatment in aeration reactor. The following aspects were studied in this thesis:1. Optimization of some producing conditions for MnP by Phanerochaete chrysosporium . The cultivation was performed in 500-mL shake flasks (120 r/min) containing 250mL medium (pH 4.5) at 37℃, and the inoculum concentration was 1.3 X 10~6 spores/mL. The highest MnP activity was 147.3U/L in this cultivation.2. Study in regulation of nutritions and MnP activity in aeration reactor with carrier. Reactive black KNB was the basal dye and the results were as follows. 1) 10g/L glucose and 0.2g/L ammonium tartar were the optimal conditions to MnP activity and decolorizating volecity of reactive black KNB. 2) In aeration reactor the addition of dye spurred Phanerochaete chrysosporium to excrete MnP to resist bad environment. With the accumulation of dye toxicity in cells, the activity of MnP was restrained and went down. 3) Degradation of dye by Phanerochaete chrysosporium was completed in 72 hours. Absorption was the main function before degradating for 24 hours, but after degradating for 48 hours, degradation by Phanerochaete chrysosporium was the main fuction and had new colored intermediates.3. Study in regulation of inducements and MnP activity in aeration reactor without carrier. Reactive black KNB was the basal dye and the results were as follows.1) Methyl alcohol had inducing function to the synthesis of MnP and the optimal concentration was about 5mmol/L. The highest MnP activity was 138.4U/L. 2)The existance of Mn2+ had great effect on MnP activity. Low concentration of Mn2+ could induce higher activity of MnP and the optimal concentration was 0.2mmol/L. The highest MnP activity was 151U/L. 3)It had obvious efficiency on nutritions usage and decolorizating effect by Phanerochaete chrysosporium in regulation of inducements.4. Study in regulation of dyes and MnP activity in aeration reactor without carrier. Four kinds of active dye were selected. They were active black KNB, active yellow M-3RE, active red M-3BE and active colorful red M2B, and they all are sympletic azote dyes. Three kinds of concentration were selected and they were 50mg/L, 100mg/L and 200mg/L respectively. The results were as follows. 1) In the concentration of 200mg/L four kinds of dye had obvious effect, and higher concentration of dyes had toxicity to Phanerochaete chrysosporium . 2)Different types of dye had different decolorizating effect. In decolorizating volecity, it was active black KNB better than active yellow M-3RE, better than active red M-3BE and better than active colorful red M2B.