Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
38 results
Search Results
Item Advances in Computational Fluid Dynamics Modeling for Biomass Pyrolysis: A Review(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Kulkarni, A.; Mishra, G.; Palla, S.; Ramesh, P.; Surya, D.V.; Basak, T.Pyrolysis, a process for extracting valuable chemicals from waste materials, leverages computational fluid dynamics (CFD) to optimize reactor parameters, thereby enhancing product quality and process efficiency. This review aims to understand the application of CFD in pyrolysis. Initially, the need for pyrolysis and its role in biomass valorization are discussed, and this is followed by an elaboration of the fundamentals of CFD studies in terms of their application to the pyrolysis process. The various CFD simulations and models used to understand product formation are also explained. Pyrolysis is conducted using both conventional and microwave-assisted pyrolysis platforms. Hence, the reaction kinetics, governing model equations, and laws are discussed in the conventional pyrolysis section. In the microwave-assisted pyrolysis section, the importance of wavelength, penetration depth, and microwave conversion efficiencies on the CFD are discussed. This review provides valuable insights to academic researchers on the application of CFD in pyrolysis systems. The modeling of pyrolysis by computational fluid dynamics (CFD) is a complex process due to the implementation of multiple reaction kinetics and physics, high computational cost, and reactor design. These challenges in the modeling of the pyrolysis process are discussed in this paper. Significant solutions that have been used to overcome the challenges are also provided with potential areas of research and development in the future of CFD in pyrolysis. © 2023 by the authors.Item The fermentation reaction producing biosurfactant using Pseudomonas aeruginosa CFTR?6 was studied. The progress of the bioreaction was monitored in terms of biomass production, product formation and substrate consumption in shake flask experiments using different initial sugar concentrations. A logistic model for biomass growth was found to be satisfactory. Average estimates of the specific growth rate, biomass yield coefficient and maintenance coefficients were obtained. Copyright © 1991 Society of Chemical Industry(A mathematical model for the production of biosurfactants by Pseudomonas aeuginosa CFTR?6: Production of biomass) Ramana, K.V.; Charyulu, N.C.L.N.; Karanth, N.G.1991Item Biological phenol removal using immobilized cells in a pulsed plate bioreactor: Effect of dilution rate and influent phenol concentration(2007) Shetty K, K.V.; Ramanjaneyulu, R.; Srinikethan, G.The continuous aerobic biodegradation of phenol in synthetic wastewater was carried out using Nocardia hydrocarbonoxydans immobilized over glass beads packed between the plates in a pulsed plate bioreactor at a frequency of pulsation of 0.5 s-1 and amplitude of 4.7 cm. The influence of dilution rate and influent phenol concentration on start up and steady state performance of the bioreactor was studied. The time taken to reach steady state has increased with increase in dilution rate and influent phenol concentration. It was found that, as the dilution rate is increased, the percentage degradation has decreased. Steady state percentage degradation was also reduced with increased influent phenol concentration. Almost 100% degradation of 300 and 500 ppm influent phenol could be achieved at a dilution rate of 0.4094 h-1 and more than 99% degradation could be achieved with higher dilution rates. At a higher dilution rate of 1.0235 h-1 and at concentrations of 800 and 900 ppm the percentage degradation has reduced to around 94% and 93%, respectively. The attached biomass dry weight, biofilm thickness and biofilm density at steady state were influenced by influent phenol concentration and dilution rate. © 2007 Elsevier B.V. All rights reserved.Item Biological sulfide oxidation using autotrophic Thiobacillus sp.: Evaluation of different immobilization methods and bioreactors(2009) Ravichandra, P.; Gopal, M.; Jetty, A.Aims: Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied. Methods and Results: Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl2 concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations. Conclusions: The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage. Significance and Impact of the Study: Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation. © 2009 The Society for Applied Microbiology.Item Studies on exhaust emissions of mahua oil operated compression ignition engine(2009) Kapilan, N.; Reddy, R.P.The world is confronted with fossil fuel depletion and environmental degradation. The energy demand and pollution problems lead to research for an alternative renewable energy sources. Vegetable oils and biodiesel present a very promising alternative fuel to diesel. In this work, an experimental work was carried out to study the feasibility of using raw mahua oil (MO) as a substitute for diesel in dual fuel engine. A single cylinder diesel engine was modified to work in dual fuel mode and liquefied petroleum gas (LPG) was used as primary fuel and mahua oil was used as pilot fuel. The results show that the performance of the dual fuel engine at the injector opening pressure of 220 bar and the advanced injection timing of 30°bTDC results in performance close to diesel base line (DBL) operation and lower smoke and oxides of nitrogen emission.Item Screening and optimisation of bioconversion parameters for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one(2009) Brahmani Priyadarshini, S.R.; Mugeraya, G.; Sandhyavali, M.S.The reduction of ketones is one of the most important and practical reaction for producing non racemic alcohols, which are needed to synthesize industrially important chemicals such as pharmaceuticals, agrochemicals and natural products. Biocatalysis has turned out to be a highly competitive technology for asymmetric ketone reduction. In the present work, an attempt was made to identify a potential microorganism for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one. Some of the fungi screened were Saccharomyces cerevisiae, Aspergillus niger(2 strains), Pichia farinosa, Candida vishwanathii, Rhizopus stolonifer and Penicillin species. The experimental results showed that S. cerevisiae, Aspergillus niger and C. viswanathii strains were able to bring about the conversion of selected ketone to alcohol. As Saccharomyces cerevisiae was found to be more effective in bringing about reduction, it was selected for further experiment. In order to improve the yield certain bioconversion parameters like pH of reaction medium, time of incubation, incubation temperature and biomass to substrate ratio were studied. The results showed that the bioreduction of the above mentioned substrate was maximum in pH 7.6 at 30°C when incubated for 48 h. The conversion increased with increase in biomass, however it reached saturation at the ratio of 300:1.Item Experimental investigation and artificial neural network-based modeling of batch reduction of hexavalent chromium by immobilized cells of newly isolated strain of chromium-resistant bacteria(2012) Shetty K, K.V.; Namitha, L.; Rao, S.N.; Narayani, M.The batch bioreduction of Cr(VI) by the cells of newly isolated chromium-resistant Acinetobacter sp. bacteria, immobilized on glass beads and Ca-alginate beads, was investigated. The rate of reduction and percentage reduction of Cr(VI) decrease with the increase in initial Cr(VI) concentration, indicating the inhibitory effect of Cr(VI). Efficiency of bioreduction can be improved by increasing the bioparticle loading or the initial biomass loading. Glass bioparticles have shown better performance as compared to Ca-alginate bioparticles in terms of batch Cr(VI) reduction achieved and the rate of reduction. Glass beads may be considered as better cell carrier particles for immobilization as compared to Ca-alginate beads. Around 90% reduction of 80 ppm Cr(VI) could be achieved after 24 h with initial biomass loading of 14.6 mg on glass beads. Artificial neural networkbased models are developed for prediction of batch Cr(VI) bioreduction using the cells immobilized on glass and Ca-alginate beads. © Springer Science+Business Media B.V. 2011.Item Multistrain probiotic production by co-culture fermentation in a lab-scale bioreactor(Wiley-VCH Verlag info@wiley-vch.de, 2016) Jangra, M.; Belur, P.D.; Oriabinska, L.B.; Dugan, O.M.Most commercial probiotic products intended for pharmaceutical applications consist of combinations of probiotic strains and are available in various forms. The development of co-culture fermentation conditions to produce probiotics with the correct proportion of viable microorganisms would reduce multiple operations and the associated costs. The aim of this study was to develop a fermentation medium and process to achieve biomass comprising the desired proportion of two probiotic strains in co-culture. Initially, a quantification medium was developed, and the method was optimized to allow the quantification of each strain's biomass in a mixture. The specific growth rates of Lactobacillus delbrueckii spp. bulgaricus and Lactobacillus plantarum were determined in media with different carbon sources. The inoculum volume was optimized to achieve equal proportion of biomass in co-culture fermentation in test tubes. Next, fermentation was carried out in a 3-L bioreactor. A biomass concentration of 2.06 g/L, with L. delbrueckii spp. bulgaricus and L. plantarum in the ratio of 47%:53% (by weight), was achieved with concomitant production of 12.69 g/L of lactic acid in 14 h. The results show that with careful manipulation of process conditions, it is possible to achieve the desired proportion of individual strains in the final biomass produced by co-culture fermentation. This process may serve as a model to produce multistrain probiotic drugs at industrial scale. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Dissolution of kraft lignin using Protic Ionic Liquids and characterization(Elsevier B.V., 2016) Rashid, T.; Chong, C.F.; Iyyaswami, I.; Murugesan, T.In the present research three Protic Ionic Liquids (pyridinium formate, pyridinium acetate and pyridinium propionate) were synthesized and tested for the dissolution and subsequent regeneration of kraft lignin. Among the investigated solvents, pyridinium formate showed a higher dissolution capacity (70% w/w) i.e. (710 g/L) at 75 °C within 1 h. The results indicated that the introduced solvent is thermally stable, noncorrosive, possesses low viscosity and is easy to recycle. The dissolution process is purely physical and the physicochemical analysis of the regenerated lignin showed high thermal stability, with reduction in polydispersity and the average molecular weight was reduced from 4119 g/mol to 1249 g/mol. FTIR spectroscopy and 1H NMR results proved that the regenerated lignin is less degraded. Moreover the OH vibrations of regenerated lignin showed a weak inter and intramolecular interaction in regenerated lignin, which could positively help in reducing its chemical resistance towards processing for further commercial applications. Due to the higher solubility of lignin and its stability towards recyclability, the pyridinium formate proved that present selective dissolution and regeneration of lignin could significantly enhance the pretreatment techniques for lignocellulosic biomass. © 2016 Elsevier B.V.Item Scale-up of naringinase production process based on the constant oxygen transfer rate for a novel strain of Bacillus methylotrophicus(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2017) Raval, K.; Gehlot, K.; Belur, B.D.Naringinase bioprocess based on Bacillus methylotrophicus was successfully scaled up based on constant oxygen transfer rate (OTR) as the scale-up criterion from 5-L bioreactor to 20-L bioreactor. OTR was measured in 5 and 20-L bioreactor under various operating conditions using dynamic method. The operating conditions, where complete dispersion was observed were identified. The highest OTR of 0.035 and 0.04 mMol/L/s was observed in 5 and 20-L bioreactor, respectively. Critical dissolved oxygen concentration of novel isolated strain B. methylotrophicus was found to be 20% of oxygen saturation in optimized medium. The B. methylotrophicus cells grown on sucrose had maximum oxygen uptake rate of 0.14 mMol/L/s in optimized growth medium. The cells produced the maximum naringinase activity of 751 and 778 U/L at 34 hr in 5 and 20-L bioreactors, respectively. The maximum specific growth rate of about 0.178/hr was observed at both the scales of operations. The maximum naringinase yield of 160 and 164 U/g biomass was observed in 5 and 20-L bioreactors, respectively. The growth and production profiles at both scales were similar indicating successful scale-up strategy for B. methylotrophicus culture. © 2017 Taylor & Francis.