Statistical Design for Optimization of Process Parameters for Biodecolorization of Reactive Orange 4 Azo Dye by Bacillus cereus Isolate

Abstract

In the present study, different approaches are being compared for the decolorization of reactive orange 4 monoazo dye by Bacillus cereus isolate under varied cultural and nutritional conditions. By employing conventional one-factor-at-a-time approach, the bacterial strain exhibited decolorization activity over a wide range of pH (7.0-9.0), temperature (30-38°C), dye concentration (50-200 mg LG 1 MSM) and inoculum size (1.0-6.0%, v/v), with peak activity (68.2% color removal) at pH 8.0, 35°C, 50 mg dye LG 1 MSM and 4.0% (v/v) inoculum in the presence of 1.0% (w/v) glucose as carbon/energy source and 0.2% (w/v) ammonium nitrate within 72 h incubation. Under response surface methodology (RSM using Box-Behnken design) approach, the dye decolorization enhanced to 100% at optimized 40 mg reactive orange LG 1 MSM, glucose 1.0% (w/v) and ammonium nitrate 0.2% (w/v) during 72 h of incubation. The dye decolorization time was advanced by 12 h in bioreactor trial and 100% color removal was achieved within only 60 h incubation. In future experimentation, we envisage to test the potential of our isolate for the decolorization of other variety of azo dyes, mixture of dyes as well as the real textile effluent.

Evaluation of molasses concentration and anoxic-aerobic react period in biodecolorization and mineralization of tartrazine (acid yellow 23)

“…As illustrated in Fig. 6, the end of anoxic react COD removal efficiency achieved in Set 2 were fluctuated between 85.63% and 92.94% (23 Jan -1 Feb), and for Set 3 between 78.74% and 89.32% (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). In term of equivalent COD reduction rate in anoxic react phase, the COD was removed at the rate ranged from 66.27 to 71.93 mg COD/L.hr in Set 2 and at the rate ranged from 82.87 to 94.00 mg COD/L.hr in Set 3.…”

“…For anoxic/aerobic react period of 12.5/8.5 hr (Fig. 7, Set 3), tartrazine removal efficiency reduced gradually from 69.33% to 37.00 % at the early stage (11)(12)(13) and maintained within the range of 27.29% to 30.59% after that, where the steady state condition had achieved (18)(19)(20)(21). Extended aerobic react duration did not show any progress with respect to tartrazine decolorization, except more consistent tartrazine removal efficiency was observed in Set 3.…”

“…Under anaerobic condition, bacterial growth is slow, so it is important to provide cosubstrate such as carbon and nitrogen source to stimulate the reduction process and to maintain the vitality of the microorganisms. Garg et al [13] explained that biodegradation of dyes is deemed to be difficult without the exogenous supplementation of carbon source. Ong et al [7] found that addition of co-substrate apparently stimulates the reduction cleavage of azo bond.…”

Optimization, kinetics, and thermodynamics aspects in the biodegradation of reactive black 5 (RB5) dye from textile wastewater using isolated bacterial strain, Bacillus albus DD1

“…Both acid and alkali environment can denature the activity of enzymes (Liu et al 2015). Also, higher pH may change the shape or charge properties of the dye molecules which may lead to complete loss of activity for most enzymes due to which the metabolic activity of the bacterial cell decreases through which they cannot able to bind the active site of the dyed surface (Garg et al 2015).…”