Study On Decolorization Of Azo Dye Wastewater By Immobilized Coriolus Versicolor And Alcaligenes Faecalis

Wastewater containing dyes is one of the main part of industrial wastewater with large discharge and deep color,and decolorization technology is one of the research focus in treatment of these wastewater.The biological method has become the main treatment method of dye-containing wastewater due to its high efficiency and no secondary pollution.However,the cultivation process of decolorizing bacteria and enzymes is laborious and tedious.Besides,the bacteria and enzymes are poor adaptability,poor reusability,and low operational stability.Immobilization of decolorizing bacteria and enzymes can effectively improve their application performance and realize to be re-used.In this study,the decolorization mechanism of acid scarlet 3R by Alcaligenes faecalis and amino Black 10B by Coriolus versicolor was respectively studied by decolorization products analysis.Afterward,a column bioreactor was constructed by C.versicolor pellets and A.faecalis immobilized on the plant carrier loofah,and the process conditions for the decolorization of double component dye wastewater which composed of acid scarlet 3R and amino black 10B were tested.In addition,the laccase from C.versicolor was firstly immobilized on the cells of A.faecalis via chemical cross-linking.The single-factor experiments and response surface methodology were used to optimize the immobilization conditions.Meanwhile,the decolorization effect of the immobilized laccase-A.faecalis on azo dye acid scarlet 3R was investigated.The main results are as follows:The main degrading pathways of acid scarlet 3R and amino black 10B were respectively elucidated by the results of UV-vis spectroscopy,FTIR,and GC-MS analysis,and that were:the degradation of acid scarlet 3R by A.faecalis was through azo bond cleavage,deamination,and desulfonation,which entered the tricarboxylic acid cycle to eventually generate non-toxic small molecules;C.versicolor degraded amino black 10B by symmetrical cleavage of the azo bond,deamination,desulfonation,and aromatic ring cleavage to form non-toxic fatty acid.The decolorization kinetic model of loofah immobilized A.faecalis on the azo dye acid scarlet 3R fitted the first-order kinetic model.Overall,the decolorization rate of acid scarlet 3R and amino black 10B in the column bioreactor which composed of Coriolus versicolor mycelial pellets and loofah immobilized A.faecalis was more than 70%.Under the conditions of both dyes concentration at 150 mg/L,the hydraulic retention time(HRT)of 12-30 h,the temperature of C.versicolor mycelial pellets packed column at 30-35℃ and Loofah immobilized A.faecalis packed column at 32-42℃,the decolorization effect of the reactor on both dyes showed well.Under the conditions of HRT of 12 h and temperature of both columns at 30℃,the decolorization rate of the reactor on both dyes could reach more than 90%when their concentration was lower than 150 mg/L.The optimum conditions for chemical immobilization of laccase on the cell of A.were:glutaraldehyde concentration 1.4%;immobilization pH 3.7;immobilization time 21 h;initial laccase concentration 16 g/L.Compared with free A.faecalis,the laccase-linked bacteria cell could reach similar decolorization rate on azo dye acid scarlet 3R,but the decolorization time was delayed.