Evaluation of two different carriers in the biodegradation process of an azo dye

Abstract

Purpose The MBBR solution has been applied for the textile wastewater treatment. However, in order to develop cost-effective solutions, waste biomass can be used as carrier. Rice husks are agricultural waste which have been used as an adsorbent of dyes; besides, they can provide and sustain suitable microorganism communities for the degradation of dyes. This study aimed to evaluate the biodegradation of the azo dye Direct Red 75 in two treatment systems with different carriers. Methods Bioreactor A was composed by an anaerobic bioreactor filled with Kaldnes K1 carriers employed in the MBBR technology and the study was performed in 2 different temperatures, 30 ± 0.5°C and 21 ± 2°C. Biofilter B was composed by a sequenced anaerobic-aerobic system with rice husks as carriers and this study was performed at 21 ± 2°C. The rice husks was also employed as a source of microorganisms in both systems. Decolourization, surface area of the carriers and other parameters were analysed. Results Biofilter B showed high rates of decolorization, mainly over 90% in all HRT tested (24, 48 and 12 h), presenting itself as a stable system, whereas Bioreactors A showed better performances with 48 h of HRT, about 85% for A at 30 ± 0.5°C and 45% at 21 ± 2°C. With a similar amount of carriers, analyses showed that rice husks had a much larger surface for microorganisms to grow on than Kaldnes K1. Conclusion The Biofilter B is a worthwhile system to be investigated and applied for the decolourization of textile wastewater treatment; for instance, in developing countries.

Rice Husk—Cellulose-Based Agricultural Waste Enhances the Degradation of Synthetic Dyes Using Multiple Enzyme-Producing Extremophiles

“…However, few studies have investigated the potential of rice husks as a significant carbon source for bacterial growth and as an accelerator in the dye degradation process. In a previous study, the azo dye Direct Red 75 was decolorized by 90% using a biofilter-sequenced anaerobic–aerobic system, with rice husks employed as carriers as a source of microorganisms [ 45 ]. In the current study, we introduced a strongly active extremophilic bacterial strain that has multiple functions—illustrating its high efficiency in dye degradation and using rice husks as a valuable carbon source for the bacteria’s growth and metabolism during the degradation process ( Figure 6 ).…”

Removal of Dyes from Wastewaters in Moving Bed Biofilm Reactors: A Review of Biodegradation Pathways and Treatment Performance

“…According to Pearce et al [57], the optimum temperature for color removal is between 35 and 45 ºC. Santos-Pereira et al [65] reported an increase in the color removal of Direct Red 75 (DR75), in an anaerobic MBBR, from 45% at 21 ± 2 °C to 85% at 30 ± 0.5 °C (Table 1).…”

“…According to Table 1, anaerobic conditions were used in most of the studies, in which biological color removal was achieved [15,23,27,39,48,55,65,68,81]. Castro et al [14] and Park et al [55] evaluated the performance of aerobic MBBRs in dye degradation and reported that no significant color removal was observed in the presence of oxygen.…”

“…Nonetheless, other sources of microorganisms may also be used. Santos-Pereira et al [65] developed the microbiota of a lab-scale anaerobic MBBR by cultivating microbes from rice husks. Vaidhegi et al [76] inoculated an MBBR with sludge from sewage treatment plants and dairy animals excrement.…”

“…The moving bed biofilm reactor (MBBR) is an example of a biofilm technology in growing expansion over the world. Recent studies have shown that this biofilm technology may be efficient for the treatment of dye-containing effluents [65,71,87]. However, the number of studies addressing the application of the MBBR process for this purpose is limited.…”