Reactive Blue 4 Decolorization under Mesophilic and Thermophilic Anaerobic Treatments

Abstract

Anaerobic decolorization of anthraquinone dye represented by Reactive Blue 4 (RB4) was studied to evaluate the factors involved in dye-reducing behaviors such as dye concentration, co-substrate, treatment temperature, salt content, and dye-reducing microbial consortia. The experiment was conducted using digested sludge treated under mesophilic (35 degrees C) and thermophilic (55 degrees C) conditions. The results indicated that the thermophilic treatment gave higher potential for this dye decolorization compared with the mesophilic one. A reduced form of RB4 did not show an auto-oxidizing reaction but treated RB4 dye was shown in light yellow color, the intensity of which was related to the initial concentration of the dye used in the treatments. Starch, which showed similar decolorizing efficiency under thermophilic conditions, could be used as a co-substrate instead of glucose for the purpose of operating cost reduction. Due to the high content of salt contained in dye wastewater, the effect of salt (NaCl) was investigated. Results showed that decolorization could be accelerated with a concentration of NaCl lower than 200 mM, but the decolorization was inhibited by high concentrations of salt. The presence of RB4 inhibited methane productivity, while total organic carbon (TOC) reduction was similar to control, without dye addition. Increasing the temperature accelerated the decolorizing potential and TOC reduction. The evaluation of dye-reducing microbial consortia was done with acidogen and methanogen inhibitors which acidogenesis microorganism was dominant in RB4 decolorization.

Decolorization of dye Reactive Black 5 by newly isolated thermophilic microorganisms from geothermal sites in Galicia (Spain)

“…Willets et al [20] was the first to report on this issue, and since then, few papers have been found in the literature. Recently, Boonyakamol et al [21] have reported the benefits of using thermophiles instead of mesophiles to decolorize a model anthraquinone dye, and dos Santos et al have widely reported the necessity of introducing redox mediators to achieve high decolorization efficiencies of several azo dyes by using anaerobic thermophiles [22][23][24][25][26][27]. However, as the anaerobic degradation of azo dyes usually produces aromatic amines, which are carcinogenic and mutagenic, the aerobic treatment is the only safe method for the biodegradation of textile azo dyes, and thermophilic aerobic treatments is yet to be studied [28].…”

Electrochemical Treatment of Wastewater containing Reactive Blue 4 (RB4) Dye: RSM and ANN Optimization, Technoeconomic Analysis and Sludge Characterization

“…Maximum experimental RB 4 colour removal and COD removal efficiencies are found to be 89.31% and 84.32%, respectively at optimum process variables (pH = 7, current density = 13.42 mAcm -2 , initial RB4 concentration = 1297.6 mgL -1 , electrode gap = 1.0 cm and contact time = 70 min), which are comparable with RSM predicted values [colour removal (88.62%) and COD removal (83.40%)]. Experimental runs of decolourization of RB 4 obtained by the CCD are used for 84% (Lee et al, 2006) 50% (Fontenot et al, 2002) 87% (Chang et al, 2009) 90% (Boonyakamol et al, 2009) 82% (Nakamura et al, 2019) 60% (Carneiro et al, 2004) 89.31% Present study…”

Effect of Various Carbon and Nitrogen Sources on Decolorization of Textile Dyes by Pseudomonas taiwanensis Strain TNZ3

“…Recent studies indicated that starch decolorization was delayed compared to glucose due to low glycoside hydrolase enzyme activity, but the combination of starch and glucose achieved good color removal yield [35]. According to Khehra et al [13], glucose acts as a co-substrate to accelerate the decolorization of RV5R when the dye concentration is increased by up to 2.5 g/l.…”