Anaerobic Decolorization Study Of Reactive Red KE-3B

With the development and application of dyes, the environmental issues were caused in dyingprocess. The chroma toxicity of dye wastewater is higher, and it’s difficult to treat, the dye wastewatertreatment approaches are mainly two kinds:(i) decolorization by physical or chemical methods of;(ii)decolorization by biological degradation, the biological method is now recognized as an environmentallyfriendly approach.Anaerobic treatment of dye wastewater, not only to make dye decolorization, but also can producebiogas, so as to achieve the purpose of reusing waste. The composition of dye wastewater is complex, toxic.How to improve the decolorization efficiency is a hot topic in current days. Dye production in the world isbeyond7×105tons every year, and azo dyes account is over half of total output, while the reactive redKE-3B is the more widely used in azo dyes. At present, the biochemical treatment of KE-3B dyewastewater has made some progress. Particular strain is isolated from activated sludge, these strains ofKE-3B decolorization can achiev decolorization purpose. Only Investigating the decolorization ofanaerobic bacteria on the KE-3B is single, some researchers used the external mediator to improve theKE-3B decolorization efficiency, such as adding composite materials and oxidation reduction media, et.al.in anaerobic decolorization process, to investigate the decolorizing effect of KE-3B. Adsorption method todeal with the KE-3B wastewater can be used for decolorization purpose, but the adsorption rate is not high,and the treatment effect is not ideal.Based on an anaerobic batch test system, the anaerobic biodegradability of reactive red KE-3B wasstudied in batch experiments under mesophilic（35℃） and thermophilic（55℃） conditions, the effectsof salt, volatile fatty acids (VFAs) and sludge adsorption et al on decolorization of reactive red KE-3B werestudied in details. The form and extent of anaerobic decolorization were detected by gas production amountand composition, and the degradation mechanism of reactive red KE-3B reduction was also discussed. Theresults, which came from study and experiment, were as follows:1）The reactive red KE-3B showed good decolorization effect in biodegradation process, and thedecolorization rate was quickly reached more than98%under thermophilic conditions at the concentrationless than80mg/L(calculated by C). With the increasing of the concentration of dyes, the reactive red KE-3B achieved high decolorization rate in long time. The thermophilic condition could improve thedecolorization rate of KE-3B. The decolorization rate achieved98%in112h under mesophilic condition,while it needed40h when under thermophilic condition.2）The results indicated that the decolorization rate was higher (more than98%) under thermophiliccondition than that under mesophilic condition when the salt concentration was less than600mM. Andunder thermophilic condition, The decolorization time extended with the salt concentration increasing.3）Some decolorized dye could recover from the former color, so we made the experiment toinvestigate the recover, the results showed that the decolorized KE-3B did not reback to red, and thedecolorized production was steady.4）The concentration of KE-3B influenced it’s adsorption, the higher concentration, induced the lowerdecolorization rate, and the effect was more obviously under thermophilic condition. In the meantime, theresults indicated that the contribution of decolorization of thermophilic adsorption was small. In theanaerobic process, the biological degradation and the absorb effect were coexisted, the main decolorizationform was adsorption under mesophilic conditon, while the main decolorization form was biochemicaldegradation under thermophilic conditon.5）Little reactive red KE-3B was mineralized under mesophilic condition, namely, little dyes wasbiodegraded. The decolorization form, which under thermophilic condition, was primary biodegradation,and the inhibition on endogenous biogas was increasing with the increase of concentration of reactive redKE-3B.The ratio of CH4in biogas was higher under mesophilic condition compared with that underthermophilic condition, and it was benefit to produce CH4under mesophilic condition. While the primarybiodegradation could occur, the evidence of mineralization was not discovered, and the ratio of CH4inendogenic biogas was lower, under thermophilic condition.