Study Of Removal Mechanism Of Typical Dyes In Dyeing And Finishing Wastewater By Activated Sludge Proscess

Reactive brilliant red E-BA,reactive black KN-B,reactive blue TQ and disperse blue XF are common dyes in printing and dyeing wastewater.Batch experiments were conducted to investigate the adsorption and degradation of four different dyes in synthetic dyeing wastewater by aerobic,anoxic and anaerobic activated sludge.FFIR-Raman and Ultraviolet spectrophotometer were used to analysis the degradation products of reactive black KN-B by aerobic,anoxic and anaerobic activated sludge.Adsorption tests were first performed to measure the adsorption capacity of aerobic, anoxic and anaerobic inactivated sludges for four different dyes.The initial concentrations of four different dyes were 30mg/L.The experiments were conducted for four different dyes separately. Effects of temperature,pH and ion concentration were also investigated.The adsorption characteristics of aerobic,anoxic and anaerobic inactivated sludge for four different dyes were similar.There was a high-speed adsorption process in the beginning 30min,the adsorption equilibrium was established in 4h.The experimental data of equilibrium concentrations were well correlated by both Freundlich and linear adsorption isothermal models,reactive blue TQ and disperse blue XF also correlated Langmuir model.Distribution coefficients(K_da decreased with the increasing temperature,that is,K_d(15℃)＞K_d(25℃)＞K_d(35℃).The adsorption process also decreased with the increasing temperature.The adsorption process was exothermic and spontaneous.Adsorption rate decreased with the increasing of pH value,when pH=3,the adsorption rate all above 95%,when pH=11,the adsorption rate all reduced under 5%,the isoelectric points of aerobic,anoxic and anaerobic sludge were:aerobic(pH_ZHC=7.5), anoxic(pH_zHc=7.1),anaerobic(pH_ZHC=6.7),There were higher adsorption capacity between negatively charged dye anions and positively charged sludge surface when pH below pH_ZHCc.As the increasing of ion concentration,dyes concentration decresed in water,the adsorption of dyes by sludge increased.Batch experiments were conducted to investigate the removal of reactive brilliant red E-BA,reactive black KN-B,reactive blue TQ and disperse blue XF by aerobic,anoxic and anaerobic activated sludge.Effects of dextrose concentration,pH value and ion concentration on the removal of four different dyes were investigated.Results showed that when no dextrose as the external carbon addition,reactive brilliant red E-BA and reactive black KN-B couldn't degradation in aerobic sludge,reactive blue TQ and disperse blue XF needed 72h and 36h to completely degraded.Anoxic sludge couldn't degradation reactive black KN-B,reactive brilliant red E-BA degradated slowly,needed 3d to completely degraded.Anaerobic activated sludge could degradated all four kinds of dyes.The degradation ability of three activated sludge were: aerobic＞anoxic＞anaerobic,degradation rate of four kinds of dyes were:disperse blue XF＞reactive blue TQ＞reactive brilliant red E-BA＞reactive black KN-B.When dextrose was exist, different states activated sludge had a better degradation rate on all four kinds of dyes.The degradation rate increased as the increasing of dextrose concentration,but when dextrose concentration more than lg/L,the active of aerobic activated sludge was inhibited,degradation ability reduce.The pH value between 7.0～9.0 has little influence on reactive brilliant red E-BA degradation by aerobic activated sludge.Reactive blue TQ and disperse blue XF had significant effect when pH=9.In anoxic and anaerobic activated sludge,pH had significant effect on reactive brilliant red E-BA and reactive black KN-B.Dye degradation rate reduced as the increasing of ion concentration,the anaerobic activated sludge had the best salt-tolerance ability.The anoxic and anaerobic activated sludge could fracture the azo double bond of reactive black KN-B,generated aromatic amines.Aromatic amines couldn't degradation in anoxic and anaerobic activated sludge.Aerobic couldn't fracture the azo double bond,but could degradation aromatic amines.