Process parameters for decolorization and biodegradation of orange II (Acid Orange 7) in dye-simulated minimal salt medium and subsequent textile effluent treatment by Bacillus cereus (MTCC 9777) RMLAU1

Environ Monit Assess (2013) 185:89098923 DOI 10.1007/s10661-013-3223-2

Process parameters for decolorization and biodegradationof orange II (Acid Orange 7) in dye-simulated minimal salt medium and subsequent textile effluent treatment by Bacillus cereus (MTCC 9777) RMLAU1

Satyendra Kumar Garg & Manikant Tripathi

Received: 20 December 2012 /Accepted: 15 April 2013 /Published online: 1 May 2013 # Springer Science+Business Media Dordrecht 2013

Abstract In this study, Bacillus cereus isolate from tannery effluent was employed for orange II dye decolorization in simulated minimal salt broth and textile effluent. Most of the physicochemical parameters of textile effluent were above the permissible limits. The strain was highly tolerant to dye up to 500 mg l1. Increasing dye concentration exerted inhibitory effect on the bacterial growth and decolorization. The maximum decolorization of initial 100 mg dye l1 was achieved at optimum pH 8.0 and 33 C under static culture conditions during 96-h incubation. Supplementation with optimized glucose(0.4 %, w/v) and ammonium sulfate (0.1 %, w/v) with3.0 % B. cereus inoculum further enhanced dye decolorization to highest 68.5 % within 96-h incubation. A direct correlation was evident between bacterial growth and dye decolorization. Under above optimized conditions,24.3 % decolorization of unsterilized real textile effluent by native microflora was achieved. The effluent decolorization enhanced substantially to37.1 % with B. cereus augmentation and to40.5 % when supplemented with glucose and ammonium sulfate without augmentation. The maximum decolorization of 52.5 % occurred when textile effluent was supplemented with optimized exogenous carbon and nitrogen sources along with

B. cereus augmentation. Gas chromatographymass spectrometry identified sulfanilic acid as orange II degradation product. Fourier transform infra red spectroscopy of metabolic products indicated the presence of amino and hydroxyl functional groups. This strain may be suitably employed for in situ decolorization of textile industrial effluent under broad environmental conditions.

Keywords Biodegradation . Decolorization . FT-IR . GC-MS . Orange II . Textile effluent

Introduction

Synthetic dyes are extensively used in printing, paper, food, pharmaceutical, cosmetic, and textile industries. Among dyes, azo is the largest class of colorants used in the textile industries. However, such dyes are electron-deficient xenobiotic compounds due to sulfonic (SO3) and colored azo (N=N) electron withdrawing groups, which generate electron deficiency in the molecule. This makes the azo dyes recalcitrant to oxidative microbial catabolism. The world annual...