Effective Anaerobic Decolorization of Azo Dye Acid Orange 7 in Continuous Upflow Packed-Bed Reactor Using Biological Activated Carbon System

Abstract

The anaerobic reduction of azo dye Acid Orange 7 (AO7) was investigated in a continuous upflow packed-bed reactor (UPBR) containing biological activated carbon (BAC). Preliminary batch experiments using graphite proved the catalytic effect of using a solid electron mediator in the reactor. Before the start of continuous experiments, AO7 adsorption studies were done to control adsorption effects on initial decolorization rates. In a continuous UPBR-BAC system, high azo dye conversion rates were achieved during very short space times (τ) up to 99% in 2.0 min. In order to know which are the crucial and most influencing properties of BAC in AO7 reduction, other materialsgraphite and aluminawith different properties were also tested in UPBRs. The results show that both electron-mediating capability and specific surface area of activated carbon contribute to higher reduction rates. Compared to other continuous and biological processes treating azo dyes, UPBR-BAC seems to be a very effective and promising system for anaerobic azo dye degradation.

Decolorization and Degradation of Azo Dyes by Redox Mediator System with Bacteria

“…However, the accelerating effects of AC gradually decrease, which is attributed to its continuous wash-out from the reactor. Similar to the above study, Mezohegyi et al achieved high decolorization rate of AO7 with an upflow packedbed reactor (UPBR) containing biological AC [39].…”

Destruction of azo dyes by anaerobic–aerobic sequential biological treatment: a review

“…Electrons obtained from oxidation of primary substrate are transferred to electronaccepting pollutants such as azo dyes directly or indirectly through redox mediators resulting in decolourization (Pandey et al 2007;Saratale et al 2011). The electrondonating primary substrates used in the reactor studies vary from simple substrates such as acetate, ethanol, yeast extract, and glucose, to more complex ones including relevant constituents of textile processing wastewaters such as starch, polyvinyl alcohol (PVA), and carboxymethylcellulose (CMC) (Carvalho et al 2008;Koupaie et al 2012;Laowansiri et al 2008;Sen and Demierer 2003;Mezohegyi et al 2007;Johnstrup et al 2011;Manu and Chaudhari 2002;O' Neill et al 2000). A given initial concentration of primary substrate to achieve decolourization of a given type of azo dye may not result in the similar extent of decolourization of a different type of azo dye at similar initial concentration (Rajaguru et al 2000).…”

Biodegradation of acid orange 7 in an anaerobic–aerobic sequential treatment system

“…where m c (g) is the mass of catalyst in the reactor, F v (mL min À1 ) is the volumetric flow rate of azo dye solution, and r (g mL À1 ) is the density of the solution [14].…”