Bio: Dipa Biswas is an academic researcher from University of Calcutta. The author has contributed to research in topics: Diesel fuel & Bioremediation. The author has an hindex of 11, co-authored 24 publications receiving 427 citations.
TL;DR: The best oil-degrading isolate, a strain of Pseudomonas aeruginosa, (BBW1), was found to degrade and multiply more rapidly in crude oil than the rest, and was associated with a single 70-kb plasmid, pBN70.
Abstract: A survey of petroleum-degrading bacteria was carried out in the Indian part of deltaic Sunderbans to evaluate the distribution of the naturally occurring petroleum-degrading aerobic bacteria. Bacteriological analysis of surface water samples collected from five different locations in the Hooghly–Matla river mouth showed that, depending on the location, 0.08–2.0% of the heterotrophic bacteria culturable in marine agar medium could degrade crude petroleum hydrocarbons as the sole source of carbon. In the entire study area, the number of heterotrophic bacteria ranged from 1 × 103 to 3.8 × 105 c.f.u/ml, amongst which 2.7 × 101 to 6 × 103 c.f.u/ml were petroleum degraders. There was a maximum number of petroleum-degrading bacteria in the waters of Haldia Port and its surrounding areas, where the water is highly polluted by hydrocarbon discharges from a nearby oil refinery and from the ships docking at the port. Among the isolates, identified on the basis of their Gram reaction, morphological and biochemical tests including the use of API20E strips, Pseudomonas, Mycobacterium, Klebsiella, Acinetobacter, Micrococcus, and Nocardia were the most common petroleum degraders. Other heterotrophic bacteria included several species of Escherichia, Klebsiella, non-oil-degrading Pseudomonas, Vibrio, Streptococcus, Staphylococcus and Bacillus. Following preliminary selection, five strains, showing best growth in medium with oil fraction as sole carbon source, were chosen for estimation of the efficiency of crude oil biodegradation. The selected strains belonged to Pseudomonas (two strains), Mycobacterium (two strains), and Nocardia (one strain). These strains degraded 47–78% of Arab-Mix crude oil over a period of 20 days. The best oil-degrading isolate, a strain of Pseudomonas aeruginosa, (BBW1), was found to degrade and multiply more rapidly in crude oil than the rest. BBW1 showed profuse growth in Bushnell Haas medium containing crude oil (as sole source of carbon) at high concentrations ranging from 0.2 to 20% (v/v), with optimum at 10%. As much as 75% of the oil was degraded within 72 h of incubation with the bacteria. Physicochemical analysis showed considerable decrease in initial boiling point and carbon residue of the degraded oil. The ability to degrade crude oil was found to be associated with a single 70-kb plasmid, pBN70. Resistance to the metals Mn2+ (50 mM), Mg2+ (200 mM), Zn2+ (6 mM), Ni2+ (10 mM) and antibiotics like ampicillin (10 μg/ml), cephalexin (30 μg/ml), nitrofurantoin (300 μg/ml) and penicillin (10 U/ml) were plasmid-mediated.
TL;DR: In this paper, a two-step process of C. rugosa lipase-mediated hydrolysis of WCO to free fatty acids (FFA) followed by Amberlyst 15H esterification of FFA with octanol was developed.
Abstract: BACKGROUND Lubricants manufactured conventionally from non-renewable mineral oil resources are not biodegradable and are liable to cause adverse environmental impacts. Biodegradable vegetable oils present a promising lubricant feedstock alternative. Waste cooking oil (WCO), which otherwise finds no immediate potential utilization can be successfully used to synthesize bio-lubricant. A novel synthetic method was developed by using the two-step process of C. rugosa lipase-mediated hydrolysis of WCO to free fatty acids (FFA) followed by Amberlyst 15H esterification of FFA with octanol. The octyl esters produced was the desired biolubricant. RESULTS The effect of different physico-chemical parameters like temperature, catalyst loading, agitation speed, molar ratio of octanol:FFA and the presence of different desiccants on the esterification reaction was examined. The optimum conditions to get maximum yield of biolubricant in minimum time were, octanol:FFA molar ratio = 3:1, temperature = 80 °C, catalyst = 2 g and desiccant (preferably silica gel powder) = 50% weight of FFA. Fourier transform infrared spectroscopy confirmed that the product formed was ester. CONCLUSION Biolubricant (octyl esters) was prepared efficiently from WCO by the two-step process developed. This novel approach represents a viable means of producing lubricants from wastes which are renewable in nature and can be an alternative to non-renewable mineral oil feedstocks. Copyright © 2012 Society of Chemical Industry
TL;DR: In this article, a mathematical model has been developed to predict the conversion of sulfur during batch type bio-desulfurization of model compounds as well as diesel having known distribution of organo-sulfur compounds.
Abstract: The bacterial strain, namely, Rhodococcus sp. (JUBT1) isolated from petrol/diesel station, has been used for different model organo-sulfur compounds like, DBT, alkylated DBT, etc., which usually remain unchanged during the conventional hydro-desulfurization of the diesel fraction. The initial concentration of organo-sulfur compounds has been varied in the range of 100–1000 mg/dm 3 . Under the present experimental range the bacterial growth has been observed to follow Haldane type kinetics characterizing the presence of substrate inhibition. Although the growth of the bacterial strain is of substrate-inhibited type for all model organo-sulfur compounds, used as limiting substrates, the extent of inhibition is, however, different. For the same values of initial concentrations the inhibition is more pronounced for the organo-sulfur compounds containing larger number of alkyl substitutions. The values of intrinsic exponential growth phase kinetic parameters like μ max , maximum specific growth rate, K S , half saturation constant, K Si , inhibition constant, have been determined using each organo-sulfur compound of different number of alkylation as limiting substrates. Relative change in the value of kinetic parameters has been correlated to the number of substitution. A mathematical model has been developed to predict the conversion of sulfur during batch type bio-desulfurization of model compounds as well as diesel having known distribution of organo-sulfur compounds. The predictions of the model have been compared with the experimental results satisfactorily.
TL;DR: In this paper, a statistical experimental design method (Taguchi L 9 orthogonal array) was implemented to optimize the experimental conditions to maximize conversion of free fatty acids (FFA) to the corresponding octyl esters.
Abstract: The enzymatic esterification of free fatty acids (FFA) from waste cooking oil (WCO) and octanol in a solvent free medium has been investigated. A statistical experimental design method (Taguchi L 9 orthogonal array) was implemented to optimize the experimental conditions to maximize conversion of FFA to the corresponding octyl esters. The optimum conditions inferred from the Taguchi analyses were: temperature = 60 °C, Novozyme 435 = 5 wt% of FFA, molar ratio of octanol:FFA = 2.5:1 and reaction time = 3 h. The product octyl ester was characterized by Fourier transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance ( 1 H-NMR and 13 C-NMR). The physico-chemical properties of the waste cooking oil and the product ester (developed from WCO) were determined following standard methods. The results revealed that the developed octyl esters have improved viscosity index, pour point, flash point and oxidation stability when compared to that of the raw material (WCO). Moreover the product is biodegradable (>90% biodegradability). Thus the synthesized octyl esters have shown potential to be used as an environment-friendly biolubricant base-oil.
••03 Mar 2015
TL;DR: This is the first study showing that an Ochrobactrum sp.
Abstract: A potential degrader of paraffinic and aromatic hydrocarbons was isolated from oil-contaminated soil from steel plant effluent area in Burnpur, India. The strain was investigated for degradation of waste lubricants (waste engine oil and waste transformer oil) that often contain EPA (Environmental Protection Agency, USA) classified priority pollutants and was identified as Ochrobactrum sp. C1 by 16S rRNA gene sequencing. The strain C1 was found to tolerate unusually high waste lubricant concentration along with emulsification capability of the culture broth, and its degradation efficiency was 48.5 ± 0.5 % for waste engine oil and 30.47 ± 0.25 % for waste transformer oil during 7 days incubation period. In order to get optimal degradation efficiency, a three level Box–Behnken design was employed to optimize the physical parameters namely pH, temperature and waste oil concentration. The results indicate that at temperature 36.4 °C, pH 7.3 and with 4.6 % (v/v) oil concentration, the percentage degradation of waste engine oil will be 57 % within 7 days. At this optimized condition, the experimental values (56.7 ± 0.25 %) are in a good agreement with the predicted values with a calculated R2 to be 0.998 and significant correlation between biodegradation and emulsification activity (E24 = 69.42 ± 0.32 %) of the culture broth toward engine oil was found with a correlation coefficient of 0.972. This is the first study showing that an Ochrobactrum sp. strain is capable of degrading waste lubricants, which might contribute to the bioremediation of waste lubricating oil-contaminated soil.
TL;DR: The two major approaches to enhance bioremediation are biostimulation and bioaugmentation provided that environmental factors, which determine the success of biOREmediation, are maintained at optimal range.
Abstract: Environmental pollution has been on the rise in the past few decades owing to increased human activities on energy reservoirs, unsafe agricultural practices and rapid industrialization. Amongst the pollutants that are of environmental and public health concerns due to their toxicities are: heavy metals, nuclear wastes, pesticides, green house gases, and hydrocarbons. Remediation of polluted sites using microbial process (bioremediation) has proven effective and reliable due to its eco-friendly features. Bioremediation can either be carried out ex situ or in situ, depending on several factors, which include but not limited to cost, site characteristics, type and concentration of pollutants. Generally, ex situ techniques apparently are more expensive compared to in situ techniques as a result of additional cost attributable to excavation. However, cost of on-site installation of equipment, and inability to effectively visualize and control the subsurface of polluted sites are of major concerns when carrying out in situ bioremediation. Therefore, choosing appropriate bioremediation technique, which will effectively reduce pollutant concentrations to an innocuous state, is crucial for a successful bioremediation project. Furthermore, the two major approaches to enhance bioremediation are biostimulation and bioaugmentation provided that environmental factors, which determine the success of bioremediation, are maintained at optimal range. This review provides more insight into the two major bioremediation techniques, their principles, advantages, limitations and prospects.
TL;DR: An overview about bioremediation for petroleum hydrocarbon pollutants and explanation about hydrocarbon metabolism in microorganisms are provided with a special focus on new insights obtained during past couple of years.
Abstract: Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years.
TL;DR: It is evident that fermentative production of chemicals and biopolymers via refining of waste and by-product streams is a highly important research area with significant prospects for industrial applications.
Abstract: The transition from a fossil fuel-based economy to a bio-based economy necessitates the exploitation of synergies, scientific innovations and breakthroughs, and step changes in the infrastructure of chemical industry. Sustainable production of chemicals and biopolymers should be dependent entirely on renewable carbon. White biotechnology could provide the necessary tools for the evolution of microbial bioconversion into a key unit operation in future biorefineries. Waste and by-product streams from existing industrial sectors (e.g., food industry, pulp and paper industry, biodiesel and bioethanol production) could be used as renewable resources for both biorefinery development and production of nutrient-complete fermentation feedstocks. This review focuses on the potential of utilizing waste and by-product streams from current industrial activities for the production of chemicals and biopolymers via microbial bioconversion. The first part of this review presents the current status and prospects on fermentative production of important platform chemicals (i.e., selected C2-C6 metabolic products and single cell oil) and biopolymers (i.e., polyhydroxyalkanoates and bacterial cellulose). In the second part, the qualitative and quantitative characteristics of waste and by-product streams from existing industrial sectors are presented. In the third part, the techno-economic aspects of bioconversion processes are critically reviewed. Four case studies showing the potential of case-specific waste and by-product streams for the production of succinic acid and polyhydroxyalkanoates are presented. It is evident that fermentative production of chemicals and biopolymers via refining of waste and by-product streams is a highly important research area with significant prospects for industrial applications.
TL;DR: Low cost, renewable raw substrates, and fermentation technology in BS/BE production processes and their role in reducing the production cost are discussed.
Abstract: Diverse types of microbial surface-active amphiphilic molecules are produced by a range of microbial communities. The extraordinary properties of biosurfactant / bioemulsifier (BS/BE) as surface active products allows them to have key roles in various field of applications such as bioremediation, biodegradation, enhanced oil recovery, pharmaceutics, food processing among many others. This leads to a vast number of potential applications of these BS/BE in different industrial sectors. Despite the huge number of reports and patents describing BS and BE applications and advantages, commercialization of these compounds remain difficult, costly and to a large extent irregular. This is mainly due to the usage of chemically synthesized media for growing producing microorganism and in turn the production of preferred quality products. It is important to note that although a number of developments have taken place in the field of biosurfactant industries, large scale production remains economically challenging for many types of these products. This is mainly due to the huge monetary difference between the investment and achievable productivity from the commercial point of view. This review discusses low cost, renewable raw substrates and fermentation technology in BS/BE production processes and their role in reducing the production cost.
01 Jan 1988
TL;DR: The proposed Update is for Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW-846, Third Edition and six finalized methods are included for immediate inclusion into the Third Edition of SW- 846.
Abstract: The proposed Update is for Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW-846, Third Edition. Attached to the report is a list of methods included in the proposed update indicating whether the method is a new method, a partially revised method, or a totally revised method. Do not discard or replace any of the current pages in the SW-846 manual until the proposed update I package is promulgated. Until promulgation of the update package, the methods in the update package are not officially part of the SW-846 manual and thus do not carry the status of EPA-approved methods. In addition to the proposed Update, six finalized methods are included for immediate inclusion into the Third Edition of SW-846. Four methods, originally proposed October 1, 1984, will be finalized in a soon to be released rulemaking. They are, however, being submitted to subscribers for the first time in the update. These methods are 7211, 7381, 7461, and 7951. Two other methods were finalized in the 2nd Edition of SW-846. They were inadvertantly omitted from the 3rd Edition and are not being proposed as new. These methods are 7081 and 7761.