Decolorization Of Mixed Dyes Composed Of Azo And Anthraquinone Dyes By Co-immobilized Aspergillus Sp.XJ-2 And Aspergillus Sp.TS-A

Printing and dyeing wastewater has complex structure,high chromaticity,biodegradation-resistant.At present,activated sludge method is the mainly biological treatment technology applied in the treatment of dyestuff wastewater.But it exists some disadvantages,such as pollutant removal incompletion,decolorization effect poor,sludge bulking.In recent years,with the extensive study of dyes decolorizing fungus,fungi show great potential applications,but it also exists some shortage,such as single degradation ability,industrial application difficulty.Anthraquinone and azo dyes are the widely used synthetic dyes,so this article combined anthraquinone dyes decolorizing Aspergillus sp.XJ-2(CGMCC 12963)and azo dyes decolorizing Aspergillus sp.TS-A(CGMCC 12964)to treat mixed dyes,the results are as follows:(1)The study about degradation pathway of Disperse Blue 2BLN: the experiment of degradation broad-spectrum to dye demonstrated that TS-A had the ability to efficiently decolorize various azo dyes,XJ-2 had the ability to efficiently decolorize various anthraquinone dyes.Amongst,XJ-2 could decolorize and degrade anthraquinone dye Disperse Blue 2BLN(50 mg/L),and the decolorization rate of 93.3% was achieved at 120 h.The degradation intermediates of target dye Disperse Blue 2BLN were detected by UV-vis,FTIR and GC-MS,and the results revealed that Disperse Blue 2BLN happened obviously biodegradation and even underwent partial mineralization.In addition,the experiment of intracellular and extracellular ligninolytic enzymes showed that manganese peroxidase was the key enzyme during the decolorization process of Disperse Blue 2BLN.Meanwhile,two possible degraded pathways of target dye by XJ-2 were proposed firstly in this work.(2)The study of ligninolytic enzymes catalysis performance: the effects of temperature,pH,metal ions on extracellular ligninolytic enzymes of XJ-2 and TS-A were optimized respectively by single factor method,and the results as following,optimum temperature,laccase: 35?,40?;manganese peroxidase: 30?,35?;lignin peroxidase: 45?,50?;optimum pH,laccase: 5,6;manganese peroxidase: 4,5;lignin peroxidase: 6,7;metal ions,laccase: Cu2+,Ca2+--promotion,Fe3+--inhibition;manganese peroxidase: Mn2+--promotion,Cu2+,Al3+--inhibition lignin peroxidase: Co2+,Al3+--promotion,Sr2+--inhibition;kinetic parameters demonstrated that extracellular laccase,manganese peroxidase and lignin peroxidase of XJ-2 and TS-A showed respectively good affinity with the substrate.(3)The co-culture system construction and the interrelationship study of XJ-2 and TS-A: in order to amplify the scope of dye decolorization by fungi,the co-culture system of XJ-2 and TS-A was constructed by single factor optimization method,and the results as following: inoculation ratio was 4:4,inoculated order was simultaneous inoculation,nitrogen source was yeast extract,carbon source was sweet potato,temperature was 30?,and pH was 5,the decolorization rate of co-culture reached 98% at 72 h.Additionally,the interaction of XJ-2 with TS-A was studied by the cross marking method of tablet confrontation and determining the growth curve,decolorization rate,pH,the activities of ligninolytic enzymes both in mono-and co-culture.The results showed that XJ-2 and TS-A had a good protocooperation relationship and co-culture expanded the scope of fungal decolorization,and the decolorization rate of co-culture system to mixed dyes(50 mg/L)improved 33.1% than single strain system;(4)The decolorization study of co-immobilized XJ-2/TS-A: the XJ-2 and TS-A were co-immobilized by adsorption method to decolorize and degrade mixed dyes,in which macroporous polyurethane foam was chosed as immobilized carrier,the results as following: the decolorization rate of co-immobilized strains to mixed dyes(130 mg/L)improved about 30% than suspended co-culture strains at 48 h;co-immobilized strains showed strong tolerance to mixed dyes of different concentration,which could achieve the decolorization of 92.7% to mixed dyes of 210 mg/L at 96 h;consecutive batches experiments showed co-immobilized strains had good reusability that the decolorization rate of mixed dyes remained around 80% at the 15 th times;co-immobilized strains was used to treat smulating dyes effluent and practical dying wastewater under optimal air flow rate(0.3m3/h)optimized by single factor optimization method,results showed that the decolorization rate of mixed dyes effluent at 96 h reached 95.3% and the removal rate of COD arrived at 87%,the decolorization rate of practical dying wastewater reached 85.5% and the removal rate of COD arrived at 78.5%.