Nature Environment and Pollution Technology

Kshama A. Shroff ¹, Varsha K. Vaidya ¹

Affiliations
1 Department of Microbiology, Institute of Science, 15, Madam Cama Road, Mumbai-400 032, Maharashtra, IN

Abstract

The kinetics and equilibrium of biosorption of hexavalent chromium from aqueous solution was carried out using the dead physico-chemically treated biomass of Rhizopus arrhizus in a batch system. The biosorption characteristics of Cr(VI) ions were studied with respect to well-established parameters including pH, temperature, rotational speed, biosorbent dosage, initial metal ion concentration and contact time. The uptake of Cr(VI) decreased with an increase in pH and biomass concentration whereas it increased with an increase in the Cr(VI) concentration, temperature and rotational speed. Biosorption equilibrium was established in about 180 min. The adsorption data were analysed using the first and the second-order kinetic models as well as intra-particular rate expressions. The first-order equation was the most appropriate equation to predict the biosorption capacities of the fungal biosorbent. The sorption data obtained at pH 2.0 conformed well to both the Langmuir and Freundlich isotherm models. The reusability of the biosorbent was tested in five consecutive adsorption-desorption cycles and the regeneration efficiency was above 95%. From the practical viewpoint, the abundant and inexpensive dead fungal biomass of Rhizopus arrhizus could be used as an effective, low cost and environmental friendly biosorbent for the detoxification of Cr(VI).

Keywords

Biosorption, Hexavalent Chromium, Rhizopus arrhizus, Dead Gungal Biomass, Isotherm Models.

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Varsha K. Vaidya ¹, Sharmila Kadam ¹

Affiliations
1 Department of Microbiology, Institute of Science, 15 Madame Cama Road, Mumbai 400 032, Maharashtra, IN

Abstract

Degradation of naphthalene by Burkholderia glathei, Alcaligenes denitrificans and Pseudomonas putida was optimized with respect to various environmental factors such as pH, temperature, salinity and addition of nutrients such as nitrogen and phosphorus. Maximum growth and biodegradation occurred at 1.0% of naphthalene at 30°C, pH 8.0 and 1.5% salinity. Addition of various nitrogen sources such as urea, ammonium nitrate and ammonium chloride as well as phosphorus sources such as KH₂PO₄ and Na₂HPO₄ resulted in an increased rate of biodegradation. A carbon to nitrogen to phosphorus ratio of 93:10:0.09 yielded maximum degradation of naphthalene. The application of the naphthalene degraders in abatement of pollution caused by naphthalene was studied in soil microcosm. The usefulness of immobilization technique for bioremediation showed encouraging results.

Keywords

Polyaromatic Hydrocarbons, Naphthalene, Biodegradation, Soil Microcosm, Immobilization.

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Kshama A. Shroff ¹, Varsha K. Vaidya ¹

Affiliations
1 Department of Microbiology, Institute of Science, 15, Madam Cama Road, Mumbai-400 032, Maharashtra, IN

Abstract

The biosorption of Cr (VI) and Ni (II) ions, both singly and in a binary system, by dried biomasses of Rhizopus arrhizus and Mucor hiemalis was investigated in a batch system as a function of initial pH. The working initial pH values for Cr (VI) and Ni (II) in a single biosorption system were determined as 2.0 and 8.0 respectively. In a binary system, the optimum pH for sorption of Cr (VI) remained the same (2.0) while for Ni (II) it changed to 5.0. Although both the biomasses had a higher adsorption capacity for Cr (VI) and Ni (II) at singlecomponent situation due to the initial pH of the solution, the equilibrium uptakes of Cr (VI) and Ni (II) in the binary mixture were found to be decreasing because of the antagonistic interaction between the components. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as pH level increased for Cr (VI) and decreased for Ni (II). Adsorption isotherms were developed for the dual-metal ion system at these two pH values and expressed by the mono-component Langmuir and Freundlich adsorption models. The model parameters were estimated by the non-linear regression.

Keywords

Cromium (VI), Nickel (II), Biosorption, Binary System, Adsorption Models, Isotherms.

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Varsha K. Vaidya ¹, Ati S. Anand ¹

Affiliations
1 Department of Microbiology, Institute of Science, 15 Madame Cama Road, Mumbai-400 032, IN

Abstract

Azo dyes represent the largest class of organic colourants listed in the Colour Index (60-70%) and makeup vast majority of the dyes discharged by textile industry. Due to high cost, low efficiency and inapplicability of several physico-chemical decolourisation techniques, biological processes such as the use of white-rot fungi provide an alternative to this problem. In the present work, ability of Trametes versicolor to decolourise an azo dye viz., Reactive Black 5 was evaluated under shaker conditions by statically grown culture using different sources of carbon and nitrogen. At the end of the 8 hours, Reactive Black 5 was decolourised to an extent of 25.12% in the medium containing glucose. The nitrogen source that supported the highest decolourisation (62.93%) of the dye at the end of 24 hours was yeast extract. Further optimization was carried out by the Orthogonal Array design for the optimization of the medium and to determine the effect of glucose, yeast extract and copper sulphate on the dye decolourisation. The data were analysed using Minitab software 15.

Keywords

Dye Decolourisation, Reactive Black 5 Dye, Trametes versicolor, White Rot Fungi, Orthogonal Array Design.

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Varsha K. Vaidya ¹, Minu Ali Manzoor ¹

Affiliations
1 Department of Microbiology, Institute of Science, 15 Madame Cama Road, Mumbai-400 032, IN

Abstract

The discovery of horizontal dissemination of antibiotic resistance in the environment has focused the attention on bacteria carrying infectious drug resistance plasmids (R factors). In the present study, 10 water samples from different coastal marine environments of Mumbai were analysed. Twenty seven organisms including E. coli, K. pneumoniae, P. aeruginosa and Salmonella paratyphi B were isolated. Evaluation of the isolates for their antibiotic resistance by the disc diffusion method revealed varying patterns of resistance to the antibiotics. Plasmid encoded resistance was seen in 74% of the isolates as shown by the loss of plasmids by acridine orange curing. Organisms were further assessed for their ability to transfer the antibiotic resistance by employing sediment associated transformation and transformation in beaker microcosms using the selected representative isolates. Intergeneric transfer of resistance in the natural environment was observed among the isolates by coincubation.

Keywords

Antibiotic Resistance, Pathogenic Bacteria, Marine Environment, Drug Resistance Plasmids, R Factors.

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Rashmi B. Kurlekar ¹, Ranjana G. Khade ¹, Varsha K. Vaidya ¹

Affiliations
1 Department of Microbiology, Institute of Science, Madam Cama Road, Mumbai 400 032, IN

Abstract

The anionic surfactants, especially linear alkyl benzene sulphonate (LAS) has been the most important industrially produced surfactant detected in urban sewage. Because of its poor biodegradability, LAS accumulates in the environment. In the present investigation, Pseudomonas aeruginosa, able to grow luxuriantly at LAS concentration of 150 μg/mL, was isolated from the urban sewage by enrichment culture technique. Its ability to degrade LAS was studied over a period of six days along with changes in biomass and pH. The estimation of the residual LAS by methylene blue method showed 98% degradation of LAS. The biologically treated waste water showed its potential to be used as irrigation water.

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