Asha Lata Singh

Removal of arsenic(III) from waste water using Lactobacillus acidophilus.

ABSTRACT Lactobacillus acidophilus was used for the removal of As(III) from 50–2000 ppb As(III)-containing water solution. Biosorption of As(III) by L. acidophilus was dependent on concentration (50 to 2000 ppb) and time (0 to 3 h).L. acidophilus(1 mg dry wt/ml) was able to remove 30, 60, 300, 420, 600 ppb As(III) from 50, 100, 500, 1000, and 2000 ppb of As(III)-containing water solution, respectively, within 3 h at pH 7. Moreover, by increasing the biomass of L. acidophilus(2 mg dry wt/ml) removal of As(III) was enhanced 1.66, 1.33, 1.16, 1.42, and 1.33 times, respectively. Fourier transform infrared (FTIR) and electron spectroscopy for chemical analysis (ESCA) spectrum of As(III)-loaded biomass was also investigated. An FTIR sample spectrum of L. acidophilus fresh biomass and As(III)-loaded biomass showed band stretching of fresh and As(III)-loaded biomass for O-H, 3423.43 to 3385.04 cm−1, and for C-O, 1742.82 to 1731.14 cm−1, and signified that –OH and –CO groups were also involved in the removal of As(III) from As(III)-containing water solution.

Experimental study on demineralization of coal with Pseudomonas mendocina strain B6-1 bacteria to obtain clean fuel

We present the results of the investigations carried out on the demineralization of coal of the Rajmahal Gondwana basin of India using Pseudomonas mendocina strain B6–1. Petrographically these coals are characterized by high concentration of inertinite macerals with subordinate amount of vitrinite and liptinite macerals. The mineral matter content occurs in high concentration which gives a high ash yield. This coal contains relatively high content of major, minor and trace elements when compared with the Clarke values in coal. After the bacterial treatment a considerable reduction in the elemental content of oxygen, hydrogen and sulphur was seen. Reduction in the ash content (>5%) was achieved and variable degrees of removal of the various major, minor and trace element concentration was also noticed. Nearly 59% removal of Mn, 53% of Na, 13% of Fe was achieved among the major/minor elements while nearly 54% of As, 41% of Cd, 39% of Cu, 34% of Ni, 32% of Zn, 13% of Cr, 43% of Co and 66% of Pb could be removed. Arsenic, Fe and Ca have a strong positive correlation with the ash removal percentage indicating that the samples having increased concentration of these elements are prone to demineralization with Pseudomonas mendocina strain B6–1. Whereas the elements like Ni, Zn, Cr and Cu maintain a strong negative correlation with the ash removal percentage indicating that their enrichment could have hampered the process of demineralization.

Demineralization of Rajmahal Gondwana coals by bacteria: Revelations from X-ray diffraction (XRD) and Fourier Transform Infra Red (FTIR) studies

The present paper entails the results of the demineralization of the Rajmahal Gondwana coals of India with Pseudomonas mendocina strain B6-1 and its signatures revealed in the X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectra. The XRD study reveals the reduction of pyrite phase in the coal samples after bacterial treatment due to bio-oxidation of pyrite and the appearance of few new phases of jarosite. Moreover, the intensity of jarosite peaks has been noticed to increase after the bacterial treatment. The FTIR spectra of the bacterial treated Rajmahal coal samples indicate shifting of the absorption peaks as compared to the control samples. The oxidation of pyrite due to the bacterial action and its conversion into jarosite is indicated by the stretching of OH bond at 630 cm−1 peak. While the bacterial action on clay minerals in all the samples is indicated by the stretching of bonds at 1114 cm−1 to 430 cm−1 peaks.

Biomethanization of Coal to Obtain Clean Coal Energy: A Review

This paper entails a review on the possibility of methanization of coal using microbial tool. Biomethanization process of coal begins with biodegradation of coal by specific bacteria and fungi. As a result of this, major polymers present in coal like proteins, polysaccharides, nucleic acids and lipids are hydrolyzed to monomers like aminoacids, sugars, purines, pyrimidines and long chain fatty acids. Their subsequent fermentation forms hydrogen, CO2 and a number of reduced compounds like alcohols, short chain fatty acids, organic acids and certain aromatics. The oxidation of these reduced compounds further leads to the formation of acetate, hydrogen and CO2, methylated compounds and several intermediate compounds. Syntrophic relationship exists between fermenting bacteria and methanogens. The resultant oxidized compounds of fermenting bacteria are gradually utilized by specific methanogens to form methane. Hydrogenotrophic methanogens utilize H2 and convert CO2 into methane. Whereas acetate is utilized by acetoclastic methanogens to generate methane. The methylated compounds are utilized for methane formation by methylotrophic methanogens.

Desulfurization of selected hard and brown coal samples from India and Indonesia with Ralstonia sp and Pseudoxanthomonas sp

The present paper entails the investigations on the removal of total sulfur (S t ) from the coal samples of four coal and lignite fields of India and Indonesia by Ralstonia sp and Pseudoxanthomonas sp. Minimum desulfurization (in relative%) was observed in Nagaland coals (India) which contain maximum quantity of S t (6.86%) among the samples of the studied area while higher removal (in relative%) was observed in coals containing relatively low quantity of S t . Nevertheless, a positive correlation exists between S t and removal percentage in samples of all coalfields indicating an increase in removal% with increasing concentration of S t . The removal percent (with respect to its initial S t ) by Pseudoxanthomonas sp in the investigated area is in order of: Vastan (mean 41.84%) > Indonesian (mean 34.16%) > Nagaland (mean 18.26) coals. In case of removal by Ralstonia sp the order of removal % can be put as: Vastan (mean 45.50%) > Rajpardi (mean 42.93%) > Indonesian (mean 20.22%) > Nagaland (mean 11.83%) coals.

Environmentally Sensitive Major and Trace Elements in Indonesian Coal and Their Geochemical Significance

Coal samples from Tarakan basin of East Kalimantan, Indonesia are analyzed for selected major and trace elements and significance of the relationships established among them. They contain high concentrations of Ca, Fe, Mn, Na, K, Cd, Cu, Cr, Ni, Pb, and Zn as compared to Clark’s values for upper continental crust and bituminous coals. The correlation matrix among them indicates a positive relation of Cr, Fe, Mn, Na, K, and total sulphur with inorganic matter. This indicates their derivation from a detrital source. However, Ni and Ca have shown a strong affinity with organic matter.

Petrographic considerations in demineralization of coal with bacteria: A new dimension in understanding the clean coal technology

The present study reveals that there is close relation between the petrographic composition of coal and removal of major, minor and trace elements/metals with bacteria. While increase in total huminite concentration has favoured the removal of Cr, Ni, Pb and Mg, there is good removal of Cd and Cu with increase in liptinite content. Inertinite is found to be favourable for the removal of Cd, Fe and K. It is therefore important to take into consideration the petrographic composition of coal when trying for the beneficiation of coal with bacteria. This will be helpful in designing suitable strategy for the removal of environmentally sensitive elements/metals with the help of bacteria and to obtain clean fuel from coal.

Petrological considerations for the demineralization of Rajmahal coals with Pseudomonas mendocina B6-1

The present study entails the results of the petrological coniderations for demineralization of Rajmahal Gondwana coals with Psudomonas mendocina B6-1. Inertinite group macerals are the dominant constituents of these coals, followed by vitrinite group, while liptinite occurs in low concentration. The amount of Mineral matter is moderately high. The concentration of major, minor and trace elements is high when compared with Clarke values. After the treatment of these coals with Pseudomonas mendocina strain B6-1, a significant reduction in the elemental content of oxygen, hydrogen and sulphur was observed. A gradual reduction of pyrite phase due to bioleaching was identified and its signatures were reflected in the XRD spectra and FTIR absorption bands. Over 5 % reduction in the ash content and decrease of major, minor and trace element to variable degrees were also noticed. Fe, As, and Ca positively correlate with the ash removal percentage indicating that the samples with high concentration of these elements were prone to demineralization with Pseudomonas mendocina strain B6-1 whereas Ni, Zn, Cr and Cu, negatively correlate with the ash removal percentage and shows that their enrichment impeded the process of demineralization. With increasing concentration of vitrinite the removal of major/minor/trace elements also increased which is attributed to the possible association of these elements with the mineral matter occurring as superficial mounting and superficial blanketing over the vitrinite macerals. This could facilitate the bacterial access to the elements to act upon and remove it to the variable extent. Some minerals occur intergrown with inertinites causing restricted bacterial action owing to the nonexposure of the mineral particles and less surface area available to the bacteria for bioleaching. Sulfur removal strongly relates with increase in inertinite content and decrease in liptinite content. This appears that sulfur associated with liptinites have shown difficult removal condition. The maximum removal of the trace elements like Cd, Cu, Co, Zn and Pb was observed from the ‘banded dull coal’ samples of the Rajmahal basin while maximum removal of major/minor elements like Fe, Ca and Mg was noticed from the ‘banded bright coal’ samples. However, maximum removal of Mn and As was also observed in the samples of ‘banded coal’.

Sequestration of Metals from Coal Using Bacteria: Environmental Implications on Clean Coal Energy

Burning of coal in power plants generates a huge amount of ash containing heavy metals posing environmental pollution. These metals, when they enter into water, air, and soil, ultimately affect human health through the food chain and food web processes. The physicochemical methods available for the removal of minerals and trace elements from coal are not only costly but also generate secondary sludge and create pollution problems. A bacterial technique is successfully used to remove hazardous metals from coal through oxidation, acidification, and adsorption, thereby improving the fuel quality.

Iron oxidizing bacteria: insights on diversity, mechanism of iron oxidation and role in management of metal pollution

In natural ecosystems, diverse iron oxidizing bacteria are of common occurrence. Basically, two different mechanisms have been proposed for catalysis of iron oxidation by bacterial metabolic systems which differ mainly at cytochrome and rusticyanin level. Biological iron oxidizers not only affect the cycling of iron but also efficiently minimize the concentrations of hazardous metals such as lead, nickel, copper, chromium, cadmium and cobalt. The ferric iron generated after biological oxidation forms complexes with metals/metalloids present in their vicinity. Ferric ions produced by biological actions also act as catalyst for oxidation of toxic metalloid such as arsenite (As III) converting it into less toxic form. Most importantly, bacterial iron oxidizers have commercially been employed in industrial bioleaching for the recovery of important elements and remediation of acid mine drainage water. Currently, heavy metal contamination has emerged as one of the prime concerns for the world and is posing serious threats to both environment and human health. Although varieties of physical and chemical techniques are currently being used to manage the metal contamination, treatment using biological iron oxidation approaches are convincing because of their ecofriendly nature and low sludge generation. In the present review we have tried to focus on the diversity of bacterial iron oxidizers, mechanisms of iron oxidation by bacterial species, and role of bacterial iron oxidizers in bioremediation of metal pollutants along with future research possibilities in this area.