Papers by Bidus Kanti Das
ABSTRACT The performance of passive sulfidogenic systems for the treatment of sulfate rich wastew... more ABSTRACT The performance of passive sulfidogenic systems for the treatment of sulfate rich wastewater decreases over time due to the exhaustion of organic carbon. Bioreactors filled with spent mushroom compost (SMC) exhibited 90% sulfate removal for approximately 11 weeks in continuous operation. Performance efficiency declined sharply when dissolved organic carbon (DOC) concentration in the reactors reached below . With an objective to reactivate sulfate removal in organic carbon exhausted SMC packed bioreactor, external pulse dosing of filtered sweatmeat waste (SMW) fraction was introduced. Various nitrogen compounds along with filtered SMW were tested as external dosing material. The effect of CaO and NaHCO3 as neutralizing agents was also evaluated on process performance during external dosing. The mass loading ratio of chemical oxygen demand (COD) to sulfate was maintained at 1:1. Bioreactors started to reactivate within a week after SMW dosing and achieved approximately 60% sulfate reduction. SMW fraction when combined with NH4HCO3 as nitrogen source provided superior sulfate reduction performance compared to NH4Cl and bacto-tryptone. Steady COD and DOC consumption to sulfate reduction mass ratios of approximately 1 and 0.5, respectively, were achieved with 70% electron flow towards sulfate reduction in this condition. Buffering with bicarbonate enhanced sulfate reduction as compared to lime. The results can be useful for reviving the performance of field treatment schemes where SMC and other similar substances are used as organic matrix.
The South Pacific Journal of Natural Science, 2008
The present study evaluated the antibacterial potentiality of hot aqueous and methanol solvent ex... more The present study evaluated the antibacterial potentiality of hot aqueous and methanol solvent extract of mature leaves of Polyalthia longifolia (Sonn.) Thwaites (Magnoliales: Annonaceae) against six reference bacteria viz. Staphylococcus aureus MTCC 2940, Bacillus subtilis MTCC 441, Escherichia coli MTCC 739, Klebsiella pneumoniae MTCC 530, Proteus vulgaris MTCC 426 and Enterobacter aerogenes MTCC 111. A sensitivity test performed with commercially available sensitivity test disks resulted in the appearance of multiple drug resistance phenotypes as all the tested bacteria are resistant to amoxycillin, cloxacillin, penicillin G and ampicillin. Most effective antibiotic against bacteria includes ofloxacin against S. aureus and K. pneumoniae; cephalexin against P. vulgaris; ciprofloxacin against E. coli and B. subtilis; kanamycin against E. aerogenes. When antibacterial potentiality of hot aqueous and methanol solvent extract of mature leaves of P. longifolia was evaluated against the bacteria, highest antibacterial activity was observed against K. pneumoniae in both the extracts followed by E. coli in hot aqueous extract and B. subtilis in methanol extract as evident from MIC values. Chromatographic analysis of the methanol extract of P. longifolia revealed the presence of steroids, alkaloids, biterpenoids, carbohydrates, amino acids, essential oil, phenolics and flavonoids as major phytochemicals.
Indian Journal of Microbiology, 2011
Rhizobium–legume symbiotic interaction is an efficient model system for soil remediation and recl... more Rhizobium–legume symbiotic interaction is an efficient model system for soil remediation and reclamation. We earlier isolated an arsenic (As) (2.8 mM arsenate) tolerant and symbiotically effective Rhizobium strain, VMA301 from Vigna mungo and in this study we further characterized its efficacy for arsenic removal from the soil and its nitrogen fixation capacity. Although nodule formation is delayed in plants with As-treated composite when the inoculum was prepared without arsenic in culture medium, whereas it attains the significant number of nodules compare to plant grown in As-free soil when the inoculum was prepared with arsenic supplemented medium. Arsenic accumulation was higher in roots than root nodules. Nitrogenase activity is reduced to almost 2 fold in plants with As-treated soil but not abolished. These results suggest that this strain, VMA301, has been able to establish an effective symbiotic interaction in V. mungo in As-contaminated soil and can perform dual role of arsenic bioremediation as well as soil nitrogen improvement.
Reviews in Environmental Science and Bio/technology, 2009
Passive remediation of Acid Mine Drainage (AMD) is a popular technology continuously under develo... more Passive remediation of Acid Mine Drainage (AMD) is a popular technology continuously under development for more than 50 years now. Roles of eukaryotes, the natural residents of AMD and its attenuator are not emphasized adequately. Studies suggest that macrophyte distinctively generate alkalinity through benthic sediments as part of root respiration. Other eukaryotic populations effectively enrich the carbon source for maintaining sulphate reducing bacterial (SRB) populations and act symbiotically. Algae produce anoxic zones for SRB action and help in biogenic alkalinity generation. While studies on algal populations and actions are relatively available those on fungal population are limited. Fungi show capacity to absorb significant amount of metals in their cell wall, or by extra cellular polysaccharide slime. This review examines the roles of these microorganisms and documents their activities in holistic form in the mine water environment. This work discusses the potential areas of likely future research that could enable AMD remediation using active eukaryotes to be made on sound understanding.
Journal of Herbs, Spices & Medicinal Plants, 2011
In in vitro screenings of antibiotics against the two most commonly found opportunistic bacteria ... more In in vitro screenings of antibiotics against the two most commonly found opportunistic bacteria related to epizootic ulcerative syndrome of fishes—Aeromonas hydrophila (MTCC 646) and Pseudomonas fluorescens (MTCC 103)—gentamycin, ofloxacin, kanamycin, and tobramycin were effective. The antibacterial screening of plant extracts revealed that both aqueous and methanolic extract of Terminalia chebula, Polyalthia longifolia, Terminalia bellerica, and Phyllanthus emblica were sensitive against the bacterial strains. Methanolic extracts of all the plant species demonstrated higher antibacterial property than the hot aqueous extracts.
Environmental Earth Sciences
Spent mushroom compost (SMC) is widely used as reactor matrix in passive bioreactor involving sul... more Spent mushroom compost (SMC) is widely used as reactor matrix in passive bioreactor involving sulfate reducing bacteria (SRB) for acid mine drainage (AMD) treatment. Follow-up our previous report, recent work has been established the extent of activity, sustained organic carbon availability, and the biochemical events of successive alkalinity producing system-based chemo-bioreactor for continuous performance using SMC. Removal of iron and sulfate from influent was over 77 and 90%, respectively, for first 13 weeks, while sulfate removal efficiency suddenly dropped down to 31% thereafter. Ahead of 13th week, process failure was beginning to be noticed when available dissolved organic carbon (DOC) value dropped down to 50 mg/L. SRB population was mostly affected with DOC drought at this stage. Sulfur was one of the major elements found with other tested metals in blackish green effluent precipitate. Sulfide compounds of the tested metals were formed on both exhausted chemo-bioreactor bed and precipitate. FTIR analysis indicated that SMC was responsible for metal binding and available nutrients supply. The present study revealed the feasibility of SMC as a host for treating AMD by this chemo-bioreactor that will assist in designing the continuous treatment practice.
Mine Water and The Environment, 2010
Static and continuous experiments were carried out in a down flow chemo-bioreactor, modeled on su... more Static and continuous experiments were carried out in a down flow chemo-bioreactor, modeled on successive alkalinity producing systems, for acid mine drainage treatment. Spent mushroom compost (SMC) was used as the immobilizing substrate and nutrient source for sulfate reducing bacteria (SRB). Operational success was assessed using effluent to influent ratios during continuous flow; these averaged: 0.0175, 0.12, and 0.071 for Fe, Cu, and Mn, respectively, and 0.11 for sulfate. In contrast, Mg was released by the SMC, increasing its concentration in the effluent. Acidity was consistently less than 1 mg/L. The pH of the effluent was higher than 7 for most of the experiment. SMC was shown to release sufficient organic carbon during the experiment to establish and maintain anaerobic conditions and sustain the SRB.
Journal of Natural Medicines, 2008
Antibacterial activity of hot aqueous and methanolic extracts prepared from six plants (Terminall... more Antibacterial activity of hot aqueous and methanolic extracts prepared from six plants (Terminallia chebula, Terminallia bellerica, Phyllanthus emblica, Punica granatum, Lawsonia alba and Mikania micrantha) used in traditional folk medicines of India were screened against five pathogenic bacteria (Staphylococcus aureus MTCC 2940, Bacillus subtilis MTCC 441, Escherichia coli MTCC 739, Proteus vulgaris MTCC 426 and Enterobacter aerogenes MTCC 111). The highest antibacterial potentiality was exhibited by the methanolic leaf extract of T. chebula, followed by the aqueous fruit extract of T. bellerica. The leaf extract of T. chebula can be considered to be as equally potent as the most effective antibiotics, such as ciprofloxacin, gentamycin, kanamycin, ofloxacin and cephalexin. A sensitivity test performed with commonly used sensitivity test disks resulted in the appearance of multiple drug resistance phenotypes of the bacteria tested. A comparision of data in the inhibition zones of pathogenic bacteria showed that gentamycin, ofloxacin, kanamycin and tobramycin were effective against all of the bacterial strains tested.
Mine Water and The Environment
Sulfate concentrations are determined in mine water by gravimetric, titrimetric, colorimetric, tu... more Sulfate concentrations are determined in mine water by gravimetric, titrimetric, colorimetric, turbidometric, ion chromatographic, inductively coupled plasma absorption spectrophotometric, and other methods. Accurate sulfate measurement of mine water can be difficult due to interfering groups, cations, and anions, mainly arsenate (AsO4 3−) and phosphate (PO4 3−). In this paper, a simple and effective spectrophotometric method is described for the determination of sulfate in mine water. When the SO4 2− reacts with barium chloranilate at pH 4.5 in aqueous ethyl alcohol solution, it releases acid-chloranilate, which shows maximum absorption at 350 nm and obeys Beer’s law over the concentration range of 10–1,000 mg/L. Results show that the proposed method was significantly more accurate than a conventional method. Absorbance was found to increase linearly with increasing concentration of sulfate, which is corroborated by the calculated correlation coefficient value of 0.999 (n = 7). The slope and intercept of the equation of the regression line were 0.00091 and 0.00778, respectively. The limit of detection and limit of quantification were found to be 0.03861 and 0.06774 mg/L, respectively. The validity of the described procedure was assessed. Statistical analysis of the result indicated high accuracy and good precision. The proposed method was successfully applied in mine water without interference from common groups like AsO4 3− and PO4 3−. The relative standard deviations of the proposed method ranged from 0.03 to 0.26%, with recoveries of 99.79–101.57%.
Water Research, 2009
Algae Fungi Bioremediation Natural alkalinity generation Carbon source a b s t r a c t Passive re... more Algae Fungi Bioremediation Natural alkalinity generation Carbon source a b s t r a c t Passive remediation of Acid Mine Drainage (AMD) is a popular technology under development in current research. Roles of algae and fungi, the natural residents of AMD and its attenuator are not emphasized adequately in the mine water research. Living symbiotically various species of algae and fungi effectively enrich the carbon sources that help to maintain the sulfate reducing bacterial (SRB) population in predominantly anaerobic environment. Algae produce anoxic zone for SRB action and help in biogenic alkalinity generation. While studies on algal population and actions are relatively available those on fungal population are limited. Fungi show capacity to absorb significant amount of metals in their cell wall, or by extracellular polysaccharide slime. This review tries to throw light on the roles of these two types of microorganisms and to document their activities in holistic form in the mine water environment. This work, inter alia, points out the potential and gap areas of likely future research before potential applications based on fungi and algae initiated AMD remediation can be made on sound understanding. (J. Bhattacharya). A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / w a t r e s 0043-1354/$ -see front matter ª
Characterization of commonly available sweetmeat waste (SMW) was carried out to encourage control... more Characterization of commonly available sweetmeat waste (SMW) was carried out to encourage controlled biological sulfate reduction. SMW was found to be mild acidic semisolid waste material that contains high sugar (520e580 mg g À1 ) and reasonable amount of utilizable organic acids for sulfate reducing bacteria (SRB). Various fractions of SMW at different concentrations were tested for usefulness to support SRB growth and sulfate reduction. Most fractions worked well in lower concentrations (COD: SO 4 2À around 1.2) with balanced bacto-tryptone supplement (C:N w11). Raw SMW was not as useful to SRB; however, filtered SMW fraction was found the most acceptable in terms of sulfate reduction (70%) e comparable to 90% reduction by pure lactate supplement. All SMW fractions supplemented media encouraged reasonable bacterial population (10 6 e10 7 cells ml À1 ). Dominance of SRB population in filtered SMW fraction (up to 93.5% of total population) among all fractions was observed by fluorescence in situ hybridization (FISH) study. Desulfovibrio desulfuricans was found to be the common SRB species in all fractioned media. Results showed that designed and regulated sweetmeat waste can be used as a proper substitute of commercially available organic carbon sources, in terms of biological sulfate reduction. Such findings point toward the prospects of commercial use of amply available SMW, hither to unreported in the literature.
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Papers by Bidus Kanti Das