Experimental Study On Treatment Of Acid Dye Wastewater By Forward Osmosis Anaerobic Membrane Bioreactor And Its Decolorization Mechanism

In recent years,forward osmosis(FO)obtains great concern in the field of environmental engineering as a new membrane separation technology.Meanwhile,a innovative process in which anaerobic bioreactor is intergrated with FO also become a research hotspot because of its efficient separation and simple process.This experiment was based on combining two technologies using anaerobic process for efficient degradation of the dye and decolorization and positive penetration for the efficient separation,and the treatment of acid dye wastewater are mainly studied.By studying the dye degradation and decolorization mechanism to characterize the membrane fouling,the performance and efficiency of the anaerobic membrane reactor were evaluated to prepare the exploration of the feasibility in industrial application.The experiment mainly contained two parts.Firstly,two kinds of acid dyes were Lanaset RED G.GR and Lanaset yellow 4GN with anaerobic bioreactor treatment to analyze the degradation mechanism by measuring COD,color,and degradation products.Secondly,the performance evaluation of Forward osmosis membrane in anaerobic bioreactor was analyzed,including membrane fouling,flux decay,salt reverse osmosis and infiltration process referred to characteristic pollutant.In the process of exploring the degradation mechanism of two kinds of acid dyes,it was found that the COD removal rate of the two dyes through anaerobic biodegradation within five days was increasing continuously.The COD removal rate of Lanaset RED G.GR increased from 54.76% to 89.53% and the removal rate of COD from Lanaset Yellow River increased from 62.62% to 81.62%.But the color removal rate of the two dyes constantly decreased.The color removal rate of RED G.GR decreased from 44.63% at one day to to 17.94% at five day,and the color removal rate of Yellow 4GN decreased from 59.31% in 1d to 12.72% at five day.Analysis of the degradation products of the two dyes using GC-MS revealed that the sorts of dye products also increased over time.During the 60-day process,no matter what was referred to the degradation of Lanaset RED G.GR or Lanaset Yellow 4GN,the conductivity in the reactor increased over time.In both reactors treating Lanaset RED G.GR and Lanaset Yellow 4CN,the effluent conductivity arised from 4673 ?s / cm to 9772 ?s / cm,and from 4902?s / cm to 7503?s / cm,respectively.Their COD degradation rate revealed the declined trend over time.The conductivity in the reactor increased over time,and in the reaction of Lanaset RED G.GR,the effluent conductivity increased from the beginning of 4673?s / cm to 9772?s / cm,and the blue 4GN reaction,the effluent conductivity from 4902?s / cm to 7503?s / cm.Their COD degradation rate within 60 days showed the decrease trend over time.The decolorization rate of Lanaset Lana free and easy yellow 4GN and Lanaset RED G.GR dropped to 5.01% and7.02%,respectively.In the FO-An MBR process onthe 60-day treatment of the two dyes,the decolorization effect was still relatively high.Two decolorization rates by the mean of FO about 98% and 99%,respectively.However,when time became changeable,there was a downward trend.For the FO-An MBR process on the two kinds of dyes in the anaerobic reactor,the retention effect of aniline compounds generated in the FO mode was not very high.The rejection rates of Lanaset RED G.GR and Lanaset Yellow 4GN were 40% and 50%,respectively.FO-An MBR long-term operation to see,membrane flux in the 60-day flux trends are gradually declining over time.However,the flux decay rate of FO-An MBR for RED G.GR dye wastewater is faster than that of Yellow 4GN.Both the fluxes at 60 days were 79.44% and 77.79%,respectively.Through the EPS and SMP and the surface morphology and SEM of the membrane analysis of membrane contamination,we can see that the two reactors due to the different water will also lead to different sludge bacteria species,and then affect membrane fouling.From the point of FO-An MBR long-term operation,membrane flux in the 60-day flux trends gradually declined over time.However,the flux decay rate of RED G.GR dye wastewater treated with FO-An MBR was faster than that of Yellow 4GN.The declined rate of the fluxes of two dyes at 60 days were 79.44% and 77.79%,respectively.Based on analysis of membrane fouling by EPS and SMP information,and surface morphology from SEM measurement,it was elucidated that the different influent in both reactorswould result in different sludge bacteria species,subsequently affecting the membrane fouling.