Department of Chemical Engineering

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Author: search.filters.author.Raghuvanshi, SmitaSubject: search.filters.subject.Chemical Engineering

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Now showing 1 - 10 of 27
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    Reforming CO2 bio-mitigation utilizing Bacillus cereus from hypersaline realms in pilot-scale bubble column bioreactor
    (Springer, 2024-03) Raghuvanshi, Smita; Gupta, Suresh
    The bubble column reactor of 10 and 20 L capacity was designed to bio-mitigate 10% CO2 (g) with 90% air utilizing thermophilic bacteria (Bacillus cereus SSLMC2). The maximum biomass yield during the growth phase was obtained as 9.14 and 10.78 g L−1 for 10 and 20 L capacity, respectively. The maximum removal efficiency for CO2 (g) was obtained as 56% and 85% for the 10 and 20 L reactors, respectively. The FT-IR and GC–MS examination of the extracellular and intracellular samples identified value-added products such as carboxylic acid, fatty alcohols, and hydrocarbons produced during the process. The total carbon balance for CO2 utilization in different forms confirmed that B. cereus SSLMC2 utilized 1646.54 g C in 10 L and 1587 g of C in 20 L reactor out of 1696.13 g of total carbon feed. The techno-economic assessment established that the capital investment required was $286.21 and $289.08 per reactor run of 11 days and $0.167 and $0.187 per gram of carbon treated for 10 and 20 L reactors, respectively. The possible mechanism pathways for bio-mitigating CO2 (g) by B. cereus SSLMC2 were also presented utilizing the energy reactions. Hence, the work presents the novelty of utilizing thermophilic bacteria and a bubble column bioreactor for CO2 (g) bio-mitigation.
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    A comprehensive review of flue gas bio-mitigation: chemolithotrophic interactions with flue gas in bio-reactors as a sustainable possibility for technological advancements
    (Springer, 2024-04) Raghuvanshi, Smita; Gupta, Suresh
    Flue gas mitigation technologies aim to reduce the environmental impact of flue gas emissions, particularly from industrial processes and power plants. One approach to mitigate flue gas emissions involves bio-mitigation, which utilizes microorganisms to convert harmful gases into less harmful or inert substances. The review thus explores the bio-mitigation efficiency of chemolithotrophic interactions with flue gas and their potential application in bio-reactors. Chemolithotrophs are microorganisms that can derive energy from inorganic compounds, such as carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2), present in the flue gas. These microorganisms utilize specialized enzymatic pathways to oxidize these compounds and produce energy. By harnessing the metabolic capabilities of chemolithotrophs, flue gas emissions can be transformed into value-added products. Bio-reactors provide controlled environments for the growth and activity of chemolithotrophic microorganisms. Depending on the specific application, these can be designed as suspended or immobilized reactor systems. The choice of bio-reactor configuration depends on process efficiency, scalability, and ease of operation. Factors influencing the bio-mitigation efficiency of chemolithotrophic interactions include the concentration and composition of the flue gas, operating conditions (such as temperature, pH, and nutrient availability), and reactor design. Chemolithotrophic interactions with flue gas in bio-reactors offer a potentially efficient approach to mitigating flue gas emissions. Continued research and development in this field are necessary to optimize reactor design, microbial consortia, and operating conditions. Advances in understanding the metabolism and physiology of chemolithotrophic microorganisms will contribute to developing robust and scalable bio-mitigation technologies for flue gas emissions.
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    Sustainable synergistic approach to chemolithotrophs—supported bioremediation of wastewater and flue gas
    (Springer Nature, 2024-07) Raghuvanshi, Smita; Gupta, Suresh
    Flue gas emissions are the waste gases produced during the combustion of fuel in industrial processes, which are released into the atmosphere. These identical processes also produce a significant amount of wastewater that is released into the environment. The current investigation aims to assess the viability of simultaneously mitigating flue gas emissions and remediating wastewater in a bubble column bioreactor utilizing bacterial consortia. A comparative study was done on different growth media prepared using wastewater. The highest biomass yield of 3.66 g L−1 was achieved with the highest removal efficiencies of 89.80, 77.30, and 80.77% for CO2, SO2, and NO, respectively. The study investigated pH, salinity, dissolved oxygen, and biochemical and chemical oxygen demand to assess their influence on the process. The nutrient balance validated the ability of bacteria to utilize compounds in flue gas and wastewater for biomass production. The Fourier Transform–Infrared Spectrometry (FT–IR) and Gas Chromatography–Mass Spectrometry (GC–MS) analyses detected commercial-use long-chain hydrocarbons, fatty alcohols, carboxylic acids, and esters in the biomass samples. The nuclear magnetic resonance (NMR) metabolomics detected the potential mechanism pathways followed by the bacteria for mitigation. The techno-economic assessment determined a feasible total capital investment of 245.74$ to operate the reactor for 288 h. The bioreactor’s practicability was determined by mass transfer and thermodynamics assessment. Therefore, this study introduces a novel approach that utilizes bacteria and a bioreactor to mitigate flue gas and remediate wastewater.
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    Assessing the bacterial consortium's potential to bio-mitigate CO2 and SO2 from simulated flue gas, wastewater bioremediation, and product characterization
    (Elsevier, 2024-12) Raghuvanshi, Smita; Gupta, Suresh
    The present study aims to fix carbon dioxide (CO2) and sulfur dioxide (SO2) simultaneously by conducting extensive semi-continuous experiments on the 3 L glass bioreactor to evaluate the potential of bacterial consortium for CO2 (C), SO2 (S), and CO2 + SO2 (CS) gaseous mixture. In this study, the bacterial consortium (Bacillus tropicus SSLMC1, Bacillus cereus SSLMC2) utilizes thiosulfate as an energy source and domestic wastewater (DWW) supplemented with additional minerals as a nutrient source. The maximum CO2 and SO2 mitigation efficiency was obtained as 93.8 % and 91.4 % for CS and S gaseous mixtures, respectively. The biomass concentration, biomass productivity, removal efficiency, and utilization efficiency for the CS gas mixture are comparable with the C and S gas mixture. Simultaneously, various nutrients and pollutants such as BOD, COD, PO43- and CO32- were removed. Fourier Transform Infrared Spectroscopy (FT-IR) and Gas Chromatography-Mass spectroscopy (GC-MS) analysis of cell lysate and cell-free supernatant have indicated the presence of fatty alcohols and long-chain hydrocarbons in all three gaseous mixtures. The present study showed that bacterial consortia can bio-mitigate CO2 and SO2 simultaneously and implement the bio-mitigation study of CO2 and SO2 in a real scenario
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    Biofiltration: Essentials, Research and Applications
    (Wiley, 2012-03) Raghuvanshi, Smita; Gupta, Suresh
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    Defluoridation studies using graphene oxidebased nanoadsorbents
    (Elsevier, 2021) Raghuvanshi, Smita; Gupta, Suresh
    The groundwater of many developed and developing countries including India has reported excessive fluoride concentrations. Various technologies are being used to remove fluoride from water but still the problem has remained unsolved. Among the available different technologies, adsorption is one of the best methods due to its easy handling, high efficiency, and lower cost. Adsorption technique with the application of nanoadsorbents has become more efficient, as the adsorption capacity is found to increase significantly due to the large surface area provided by the nanoparticles. Since the last few years, nanomaterial-related technologies have gained much attention in the field of water treatment. The previous studies have discussed the possible mechanism for fluoride ion adsorption on nanoparticles. This chapter discusses the possibility of magnesium oxide nanoparticles as adsorbents for the removal of fluoride from wastewater. This chapter demonstrated the use of modified Hummers' method for synthesizing nano-magnesium oxide (n-MgO) and nanocomposites (n-MgO-coated GOs). The developed adsorbents were characterized using various methods such as FTIR, XRD, SEM-EDX, TEM, etc. The effect of various influencing parameters such as initial pH, initial fluoride concentration, adsorbent dosage, and contact time on fluoride adsorption using developed adsorbents was studied. This chapter demonstrated the efficient removal of fluoride ions from aqueous solution using n-MgO and nanocomposites.
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    Waste water treatment plant life cycle assessment: treatment process to reuse of water
    (Elsiever, 2017) Sangwan, Kuldip Singh; Raghuvanshi, Smita
    This paper presents a life cycle assessment (LCA) of waste water treatment plant (WWTP) in a university campus in India. Various emissions coming from the WWTP along with their impact factors are analyzed using a LCA software Umberto NXT Universal utilizing Eco-invent database v3.0. It has been found that the recycled water from the plant provides positive impact on the assessed categories. Effect of treatment system is overriding the effect of recycled water in other categories like terrestrial eco-toxicity potential, global warming potential, particulate matter formation, fossil depletion potential, etc. However, the social effect of untreated sewer and environmental effect of compost produced by the system have not been studied.
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    Life Cycle Assessment of Filtration Systems of Reverse Osmosis Units: A Case Study of a University Campus
    (Elsiever, 2016) Sangwan, Kuldip Singh; Raghuvanshi, Smita
    Environmental concerns are gaining importance in ground water resource management. Reverse osmosis (RO) systems are commonly used for filtration of surface and ground water for domestic and commercial purposes. This study aims to analyze the environmental impacts of electricity, fresh water and material consumption in various types of RO systems. The evaluation tool used for this study is life cycle assessment (LCA) and for this purpose Umberto NXT Universal software with Eco-invent version 3.0 database has been utilized. The inventory analysis has been done for RO systems of four different capacities, viz 25, 50, 250, and 500 liters per hour (LPH). This research also provides comparison of quantitative impacts of different capacity RO systems. All inclusive, the study presents an insight into the environmental impacts of various RO systems used in India and also discuss the alternative technologies for filtration of surface and ground water.
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    Biodegradation kinetics of Cr (VI) by acclimated mixed culture
    (JCE, 2011-05) Raghuvanshi, Smita; Gupta, Suresh
    Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being investigated. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. It is highly toxic in nature and causes adverse effects on human beings. The present study deals with the removal of hexavalent chromium compound from industrial waste water using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation studies are conducted for an initial Cr(VI) concentration ranging from 10-50 mg/L. The enrichment of culture is carried out for a period of 7 days. In these experiments, 100 mL of minimum salt medium (MSM) is autoclaved and added with known amount of acclimated mixed culture obtained from the enrichment procedure. Known amount of Cr(VI) is added in autoclaved MSM to maintain the required concentration of Cr(VI). The flasks are kept in the rotary shaker which is maintained at 37 C and at 150 rpm throughout the biodegradation process. The samples are collected at different intervals. The obtained biomass growth is significant and indicate the considerable decrease in Cr(VI) concentration in the solution The biodegradation rate kinetic parameters are obtained for zero order and three and half order kinetic models.
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    Biofiltration for removal of methyl isobutyl ketone (MIBK): Experimental studies and kinetic modelling
    (Taylor & Francis, 2009-08-26) Raghuvanshi, Smita
    The present study deals with the biofiltration of methyl isobutyl ketone (MIBK), which is considered to be a highly toxic volatile organic compound. It is released from the paint and petrochemical industries and is one of the major contributors to air pollution. The biofiltration study was carried out on a lab scale for two months in the presence of acclimated mixed culture. The performance of the biofilter column was evaluated for different inlet loads of MIBK at air flow rates ranging from 0.18 to 0.3 m3 h−1. The maximum removal efficiency of 93% was obtained after 60 days of biofilter operation for an inlet MIBK concentration of 0.45 g m−3, and a microbial concentration of 2.36 × 108 CFU g−1 of packing material was obtained. This led to a study of shock loadings for 20 days, by varying the inlet MIBK load and air flow rate after every five days, to observe the behaviour of the biofilter column in removing sudden loads of MIBK. The biokinetic constants r max and K s were obtained using the Michaelis–Menten kinetics and were found to be 1.046 g m−3 and 0.115 g m−3 h−1, respectively, with a coefficient of determination (R 2) of 0.993. The obtained experimental results were validated with the Ottengraf and Van den Oever kinetic model. The critical inlet concentration, critical inlet load and biofilm thickness were also estimated using the results obtained from the model predictions.