Study On The Influence Of Bio-electrochemical Enhancement On Anaerobic Biological Treatment Of Printing And Dyeing Wastewater

Printing and dyeing wastewater contains many kinds of persistent organic pollutants and has the characteristics of high chemical oxygen demand(COD) and high colority. Printing and dyeing wastewater flows into the water body and it becomes one of the key factors threatening the safety of water environment in our country. Treating dyeing wastewater by biological methods is one of the most effective technologies. Expanded Granular Sludge Bed(EGSB) is a kind of anaerobic biological reactors with high speed and has development prospects at present. Nano zero-valent iron can be used not to transform pollutants, but to be as anaerobic microbial electron donor through corrosion and producing hydrogen.Start-up of the EGSB reactor was the first step. The nutrient solution made up by glucose,urea and KH2PO4 with the mass ratio of 100:5:1 was used to acclimate the anaerobic sludge in the EGSB reactor.After a 90-day operating period, COD degradation rate of the EGSB reactor remained above 90%.Then two kinds of researches of anaerobic biological treatment strengthened by bioelectrochemistry were launched:Firstly,A system combined nano zero-valent iron(nZVI) and anaerobic microorganisms was used to study the influence of the nZVI concentration,initial pH,initial X-3B concentration and temperature on the combination.Individual nZVI treatment and individual anerobic microoganism treatment were also studied. The result shows that the combination of nano zero-valent iron and a EGSB reactor works well in treating printing and dyeing wastewater.The decolorization rate of the combination could achieve 98.93% in 48 hours under the condition of 100mg/L X-3B initial concentration,0.5g/L nZVI concentraion,pH of6.0 and the temperature of 30℃.The X-3B decolorization rate of combination system is higher than individual nZVI fixed bed and individual EGSB reactor.Secondly,The system of nZVI activating potassiumsupersulphate(PS) treated the printing and dying wastewater associated with the EGSB reactor and the nZVI-PS system applied as reference.The X-3B solution was used as simulation wastewater and the influence of nZVI concentration was studied.The decolorization rate of nZVI-PS system and the combination ofnZVI,PS and EGSB was 96.68% and 99.38% respectively in 60 minutes with the nZVI concentration of 0.2g/L.The result shows that the disposal effect of combination system of nZVI,PS and EGSB is better than the nZVI-PS system.At last,a preliminary study of the reaction machanism on EGSB reactor was discussed.The acclimated sludge in the EGSB reactor was used as the target to screen three kinds of superior strains with the streak plate method.The molecular biological identification,growth curve drawing,the ability of degradate X-3B and the decolorization effect of nZVI-strain were studied prospectively.