Removal of Cr (VI) from Tannery Effluent and Aqueous Solution by Sequential Treatment with Microfungi and Basidiomycete-Degraded Sawdust

Bernard O Ejechi,Olubunmi O Akpomie

doi:10.4236/jep.2016.76069

Abstract

Removal of Cr (VI) from aqueous solution and tannery effluent in sequence with Cr (VI) resistant microfungi (Aspergillus niger, Penicillium chrysogenum) and sawdust degraded by basidiomycete (Gloeophyllum sepiarium) was investigated in the laboratory. Initial or primary treatment with microfungi reduced 200 mg/l Cr (VI) in aqueous solution by 64.6% - 78.2% while a markedly lower 0.52 mg/l Cr (VI) in tannery effluent was reduced by 72.4% - 84.6%. However, the residual Cr (VI) in both aqueous solution and tannery effluent was reduced to a non-detectable level after secondary treatment by passage through basidiomycete-degraded sawdust column. The recovery of 65.4% - 87.7% of the Cr (VI) removed by treatment microfungi by elution indicated adsorption as the major mechanism for Cr (VI) removal. The microfungi reduced BOD in tannery effluent by 85.3 ± 5.6 - 92.7 ± 6.8 and concomitantly removed Cr (VI), hence it is hypothesized that non-Cr (VI) constituents of tannery effluent may have interfered with biosorption of Cr (VI) by treatment microfungi. It is concluded that the two-stage sequential treatment process may be of potential cost-saving stratagem for removal of chromium from industrial wastes.

Highlights

The tanning industry generates wastes which include compounds such as chromium, phenol, chloride sulphideHow to cite this paper: Ejechi, B.O. and Akpomie, O.O. (2016) Removal of Cr (VI) from Tannery Effluent and Aqueous Solution by Sequential Treatment with Microfungi and Basidiomycete-Degraded Sawdust
The Cr (VI) removed from tannery effluent and aqueous solution by the microfungi peaked at the 36th hour of incubation (Figure 1)
The results of the primary treatment tests showed that the live microfungi removed over 70% of the chromium in the tannery effluent and aqueous solution and concomitantly reduced BOD by over 80% in the same effluent (Table 1)

Summary

Introduction

The tanning industry generates wastes which include compounds such as chromium, phenol, chloride sulphideHow to cite this paper: Ejechi, B.O. and Akpomie, O.O. (2016) Removal of Cr (VI) from Tannery Effluent and Aqueous Solution by Sequential Treatment with Microfungi and Basidiomycete-Degraded Sawdust. How to cite this paper: Ejechi, B.O. and Akpomie, O.O. Microorganisms have been investigated for their ability to remove chromium and other metals from aqueous solutions or industrial wastes in several studies [3]-[7]. These reports show that microorganisms can mobilize or immobilize metals by biosorption, sequestration, production of chelating agents, chemoorganotrophic and autotrophic leaching, methylation and redox transformations. These mechanisms stem from prior exposure of microorganisms to metals which enable them to develop the resistance and tolerance useful for biological treatment [8]. It has been shown that cells of plants, algae, fungi and bacteria, otherwise referred to as biomass, possess functional groups such as carboxyl, hydroxyl, sulphate, phosphate and amino that can bind metals [9]

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Conclusion