Biodecolourization of dye-contaminated textile effluents using &lt;i&gt;Bacillus cereus&lt;/i&gt; N27

W C John,B B Adamu,S B Oyeleke,Z Umar,O A Oyewole,T.T Ayisa

doi:10.4314/njb.v34i1.17

Abstract

This study examined the potentials of Bacillus cereus N27 to decolourize textile effluents. The determined physicochemical parameters of the effluents were temperature, pH, total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), biological oxygen demand (BOD) and chemical oxygen demand (COD) using standard techniques. The Bacillus cereus N27 was isolated from textile effluent contaminated soil samples in Challawa, Kano state, Nigeria and were characterized and identified based on cultural, biochemical and molecular techniques. The Bacillus cereus N27 was used for the biodecolourization study. The 3 ml broth culture of Bacillus cereus N27 was inoculated into medium comprising 2 g of yeast extract, 2 g of glucose, 2.8 g of lactose broth in 50 ml of different concentrations of the effluent (0%, 5%, 10%, 30%, 50%, 70%, 90% and 100 %) and were incubated for 30 days at 37 o C. The growth of the Bacillus cereus N27 was compared with corresponding McFarland standards. The rate of biodecolourization was determined using spectrophotometer at 600 nm. The effects of temperature (30 o C, 35 o C, 40 o C, 45 o C) and pH (4, 6, 8, and 10) on the decolourisation potential of the isolates was also determined. The results obtained for the physicochemical study were temperature (33.5 o C), pH (6.10), BOD (0.13 mg/L), COD (123.5 mg/L). DO (0.162 mg/L), TSS (310 mg/L), TDS (465.5 mg/L). The optimum biodecolourization temperature was 35 o C with 72.2% rate of biodecolourization after 30 days while pH 6 was optimum for the biodecolourization. The results obtained in the study suggest that Bacillus cereus can be used to develop an effective biological treatment system for the wastewaters contaminated with textile effluent. Key words : Textile effluent, dye, biodecolourization, Bacillus cereus .

Highlights

Environmental problems such as appearance of colour in discharges from various textile industries, coupled with the increasing volume of water consumed by these textile industries, have made the treatment of effluent and its reuse increasingly attractive to the industry (Vilaseca et al, 2010)
The role played by some bacterial species in the biodecolourization and decolourization of textile effluents has been reported by Sriram and Reetha (2015), Walter et al (2013), Karthikeyan and Anbusaravanan, (2013), Kalyanee et al (2010) and Ola et al (2011)
The Results revealed that isolates of Bacillus cereus N27 achieved 67.5% a decolourization of textile effluent respectively

Summary

Introduction

Environmental problems such as appearance of colour in discharges from various textile industries, coupled with the increasing volume of water consumed by these textile industries, have made the treatment of effluent and its reuse increasingly attractive to the industry (Vilaseca et al, 2010). Industrial effluents which contain azo dyes must be treated adequately before discharging into the environment to remove the toxicity of the dye from textile effluent (Karthikeyan, and Anbusaravanan, 2013). Microorganisms belonging to different taxonomic groups of Algae, Bacteria, Fungi, and Actinomycetes have been reported for their ability to decompose azo dyes (Olukami et al, 2006). The enforcement of permitted level of physico chemical parameters and that of heavy metals levels in discharge textile effluent has not been followed strictly. According to Tambarlini et al, 2012 some heavy metals found in these textile effluents have been found to be carcinogenic while some of the chemicals are poisonous to man and aquatic life depending on the duration of exposure and dose (World Health Organisation, WHO, 2012)

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