| A one-piece electric coupling bioreactor (BER) was constructed for studying degradation characteristic of reactive brilliant red X-3B, which was took as a typical refractory organics. Structure factor on the BER degradation effect of X-3B was studied; as well as the influence of operating parameters on BER degradating X-3B and intermediate conversion features of X-3B during decolorizing was studied.The results are as follows:In the research of BER electrode configurations and materials.Eight reactors were built with different configuration.Four BER with different cathode configurations were studied on their X-3B processing characteristics,The results show that decoloration efficiency of X-3B is closely relative to the cathode current density by unit area,the BER with the configuration which has the maximum current density and minimal apparent impedance, had the biggest X-3B decolorizing efficiency of 66.79%.The influence of filling Granular activated carbon (GAC)on BER deals with X-3B was studied. The results show that GAC can shorten the time domestication hanging membrane reactor and CODcr of effluent was not interfered by GAC,However decoloration efficiency of X-3B of GAC-BER was 17.75% lower than BER.Studied the influence of different anode materials on BER dealing with X-3B, results showed that X-3B decolorizing efficiency of a BER with Ti/IrO2-Ta2O5 coated DSA electrode was better than BER with graphite as anode. DSA electrode had a smaller breakdown voltage and internal resistance.Scanning Electron Microscope(SEM) results showed that stability and catalytic activity of DSA electrode is superior to the graphite electrode.Effects of operation parameters on X-3B degradation in BER was studied.Results showed that applied electric field promoted the microbial decolorization of X-3B,decomposition voltage of diffrient configuration BER was about 1V,current small under 0.8V,so,neither electrochemistry nor electric-biological coupling effect was obvious on X-3B decolorizing.Temperature affects X-3B decolorization rate by influencing the microbial activity and current density in BER.32℃ was the best temperature for decoloring.As the temperatures raised, current density as well as decoloring rate decreased.Appropriate amount of inorganic salt could increase the conductivity of the reaction system,thus was advantageous to the electron transfer.Compared with without NaCl,decolorization rate increased by 22.85%,when NaCl concentration was 0.33g/L.And osmotic pressure increased,when NaCl concentration was 3.30g/L,caused irreversible and toxic to microbial physiological,led to the decrease of the X-3B decolorization.BER decolorization of X-3B and intermediate transformation characteristics were studied by UV/Vis,FT IR and GC-MS scanning atlas.Results show that further degradation of organic matter such as benzene, naphthalene ring by nicrobes were not obvious,wen 0.8V.While 1V voltage could promote these organic matters to turn into hydrocarbons, aldehydes and ketones,small molecule organic matter and carboxyl and its derivatives.There was no obvious different degradation mechanisms among BER with different reactor configurations, under 1 v voltage.The degradation path of X-3B in BER was preliminary analyzed.Conjugated double bond of X-3B was prone to fracture symmetry and asymmetry,under the action of hydrogen peroxide enzyme,during which aromatic amine compounds were generated.Then aniline turned into phenol by hydrolysis,and the other aromatic amine compounds generated a variety of compounds containing naphthalene ring,benzene ring through reduction,hydrolysis and oxidation.Part of the intermediate degradated into hydrocarbon, phenols,alcohols, and lipid compounds. |
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