Biological sulphate reduction and redox mediator effects on azo dye decolourisation in anaerobic–aerobic sequencing batch reactors

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

“…Vanderzee et al (2003) observed that the presence of sulphate at concentration as high as 60 mM did not interfere with transfer of electrons to Reactive Red 2. Similarly, Albuquerque et al (2005) did not notice any improvement in decolourization capacity for Acid Orange 7 in an anaerobic-aerobic SBR even though the presence of sulphate-reducing microbes was confirmed. These results indicate that sulphate may not compete as an electron acceptor with the azo dye (thus, no production of reduced sulphur species) or even if sulphate acts as an alternative electron acceptor, the biogenic sulphide does not contribute to the reduction of dye.…”

“…The effect of redox mediator has been observed to be dependent on (1) the type of co-substrate, (2) temperature, (3) ratio of redox mediator/azo dye, and (4) the presence of trophic groups and selective inhibitors (Vanderzee and Cervantes 2009). Albuquerque et al (2005) studied effect of the presence of various RMs on anaerobic decolourization of Acid Orange 7 (AO7). Only 5 % decolourization could be achieved after 10 h of incubation in the absence of any RM.…”

“…Extent of anaerobic biological colour removal has been reported to be higher than 80 % and in some cases even 100 % for a variety of azo dyes (Karatas et al 2010;Yasar et al 2012;Da Silva et al 2012). The extent and rate of anaerobic decolourization of azo dyes are influenced by various parameters such as dye structure, dye concentration, supplementation with different carbon and nitrogen sources, electron donor, and redox mediator (Vanderzee and Villaverde 2005;Da Silva et al 2012;Johnstrup et al 2011;Koupaie et al 2011;Mohanty et al 2006;Albuquerque et al 2005). The influence of each parameter is discussed as below.…”

Optimization of Fenton-biological treatment scheme for the treatment of aqueous dye solutions

“…However, some researchers have reported that partial mineralization of few dyes can be achieved by anaerobic followed by aerobic treatment [11][12][13][14][15] but the problem associated with anaerobic treatment of azo dyes is mainly it requires long hydraulic retention time (HRT) [16,17], long sludge retention time (SRT) [16,18]. The requirement of long HRTs and SRTs increases the volume of the reactors required and thus increases the cost of installation and also the requirements of additional carbon source [19], redox mediators [20] and skilled labour increases the operating cost of treatment. The researchers have also reported that some azo dyes are toxic to anaerobic biomass [20].…”

“…However the end products formed are of concern [36]. Further these end products (aromatic amines) can be possibly degraded biologically (after acclimatization) under aerobic condition [12,13,15,[18][19][20], which is also considered to be an economical treatment. Thus a sequential Fenton's oxidationaerobic treatment chain seems to be an economical alternative for the treatment for the wastewaters containing azo dyes.…”