Faculty Publications

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    On numerical modelling of waves, currents and sediment movement around Gurupur-Netravathi river mouth
    (2010) Radheshyam, B.; Rao, S.; Shirlal, K.G.
    This paper presents an overview of the investigations that were carried out to understand the coastal process along Bengre and Ullal at the Gurupur-Netravathi River mouth in the west coast of India. This river inlet was facing problems of migration and siltation since several decades and therefore two rubble mound breakwaters were constructed during the year 1994 as an intervention to maintain the inlet mouth. After the construction of these river training jetties, the inlet was stabilized, but severe erosion has been taking place along the Ullal spit on the south side of southern breakwater, since 1996 and heavy accretion on the North of Northern Breakwater along Bengre spit, which is now almost stabilized. This study has been undertaken to understand the hydrodynamics along the beaches adjoining the river mouth. For the present study, various field data was collected for the post monsoon season of 2006. The hydrodynamic (HD), Parabolic mild slope (PMS) and Sediment transport (ST) modules of MIKE-21 software were used to understand the hydrodynamics of the study area. Before the model was made use, it was first validated by using field data to understand the hydrodynamics of the area. Since the field data is of limited duration, data collected from the NMPT wave buoy for an entire year was used for the model simulation. From the studies it was confirmed that current direction and sediment movement follow a similar pattern in monsoon and pre-monsoon and a different pattern during post-monsoon. It is observed that the main cause of erosion is due to direct action of waves on the adjoining beaches of the coast and the beaches in the study area are generally in dynamic equilibrium with a small amount of erosion at Ullal. © 2010 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Development of prediction models for hydrodynamic performance of semicircular breakwater
    (2012) Aggarwal, A.; Gope, V.K.; Managiri, S.S.; Hegde, A.V.
    Breakwaters are structures built to protect harbors, shore areas, basins, and other areas from the fury of sea waves. They create calm waters and provide for the safe mooring and handling of ships, as well as protection to harbor facilities. The main function of a breakwater is the formation of an artificial harbor. Of late, certain new types of breakwaters have been constructed to cater to the tranquility requirements of managing marine traffic in ports. The semicircular breakwater (SBW) is one such new type of breakwater. The semicircular breakwater possesses a round top and, thus, offers more stability against the action of waves. It is expected that the SBW will be well suited as an offshore breakwater designed to protect beaches from coastal erosion. A number of experiments were conducted on scaled-down physical models of SBW for different values of parameters such as wave height H, wave period T, spacing of perforations on the seaside, etc. (radius of breakwater and diameter of perforations were kept constant), and data were collected. The paper presents the prediction models/equations for hydrodynamic performance characteristics such as reflection coefficient and relative wave runup, using the data obtained by a regression approach in MATLAB.
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    Characterization of heat transfer of large orbitally shaken cylindrical bioreactors
    (Elsevier, 2014) Raval, K.; Kato, Y.; Büchs, J.
    Disposable shaking bioreactors are a promising alternative to other disposable bioreactors owing to their ease of operation, flexibility, defined hydrodynamics and characterization. Shaken bioreactors of sizes 20. L and 50. L are characterized in terms of heat transfer characteristics in this research work. Water and an 80% glycerol-water system were used as fluid. Results indicated large heat generation due to shake mixing which was observed by temperature difference between the fluid inside the vessel and the surrounding air outside the vessel. Maximum temperature difference of ca. 30. K was encountered for a 50. L vessel, at 300. rpm and 20. L filling volume. Outside heat transfer rate was governing the overall heat transfer process. Lateral air flow did increase heat transfer rates to large extent. An empirical correlation of overall heat transfer coefficient was obtained in terms of filling volume, rotational speed and lateral air flow rate. However, as the vessel thickness increased, the overall heat transfer process was limited by vessel wall resistance. © 2014 Elsevier B.V.
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    Studies on the Site-specific PEGylation Induced Interferences Instigated in Uricase Quantification Using the Bradford Method
    (Springer Netherlands, 2016) Nanda, P.; JagadeeshBabu, P.E.
    Uricase from Bacillus fastidiosus was site-specifically PEGylated using methoxypolyethyleneglycol-maleimide (mPEG-mal) of different molecular weights (750 Da, 5 kDa, 10 kDa) via Thiol PEGylation strategy. The obtained monoPEGylated uricase conjugates were characterized using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and the molecular weight of single subunit of the conjugate was found to be 42.6, 48.1 and 56.3 kDa with respect to different molecular weights of m-PEG-mal. The influence of PEGylation on the quantification of uricase using protein quantification techniques like Bradford assay, RP-HPLC detection and Dumbroff method has been evaluated. A gradual decline in the absorbance value was observed with the advancement of the PEGylation reaction, indicating an interferences in the protein quantification due to PEGylation. The extent of interference highly dependence on mPEG-mal concentration and its chain length. The present study indicates that the quantification of PEGylation induced interferences caused in protein measured ought to be prudently measured at every discrete step of the PEGylation process. © 2016, Springer Science+Business Media New York.
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    Fabrication of a novel hollow fiber membrane decorated with functionalized Fe2O3 nanoparticles: Towards sustainable water treatment and biofouling control
    (Royal Society of Chemistry, 2017) Hebbar, R.S.; Isloor, A.M.; Kulal, K.; Abdullah, M.S.; A.F., A.F.
    The development of sustainable, surface-functionalized hollow fiber membranes with advanced nanomaterials has enabled the tailoring and targeted control of their physicochemical properties. This provides the material with improved features of hydrophilicity and permeability, excellent selectivity, and superior antifouling and antimicrobial activity. We explored a new strategy using well dispersed functionalized Fe2O3 nanoparticles to fabricate a polyetherimide nanocomposite hollow fiber membrane with enhanced surface and anti-biofouling properties. To confirm the membrane modification, a series of characterizations such as contact angle, surface energy, water uptake capacity, porosity, zeta potential, and morphological analysis were performed. The permeation experiment indicated superior hydrodynamic permeability and antifouling properties with more than 95% rejection of BSA protein molecules after inclusion of a 1.5 wt% additive dosage. Moreover, the nanocomposite membrane exhibited a relatively higher normalized flux and rejection up to 94% during the filtration of hazardous natural organic matter (NOM) with differing parameters such as the feed solution pH and ionic strength. The presence of modified Fe2O3 nanoparticles in the membrane significantly inhibits the growth of bacteria and other microorganisms on the membrane surface, resulting in an enhanced anti-biofouling property. In particular, the demonstrated method illustrates a fast, facile strategy for the functionalization of Fe2O3 nanoparticles to improve the membrane properties and anti-biofouling activity, giving them great potential for effective and sustainable water treatment applications. © 2017 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
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    The combined effects of carbon/nitrogen ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a laboratory-scale anaerobic–anoxic–oxic activated sludge biofilm reactor
    (IWA Publishing, 2018) Manu, D.S.; Thalla, A.K.
    The current trend in sustainable development deals mainly with environmental management. There is a need for economically affordable, advanced treatment methods for the proper treatment and management of domestic wastewater containing excess nutrients (such as nitrogen and phosphorus) which can cause eutrophication. The reduction of the excess nutrient content of wastewater by appropriate technology is of much concern to the environmentalist. In the current study, a novel integrated anaerobic–anoxic–oxic activated sludge biofilm (A2O-AS-biofilm) reactor was designed and operated to improve the biological nutrient removal by varying reactor operating conditions such as carbon to nitrogen (C/N) ratio, suspended biomass, hydraulic retention time (HRT) and dissolved oxygen (DO). Based on various trials, it was seen that the A2O-AS-biofilm reactor achieved good removal efficiencies with regard to chemical oxygen demand (95.5%), total phosphorus (93.1%), ammonia nitrogen concentration (NH4þ-N) (98%) and total nitrogen (80%) when the reactor was maintained at C/N ratio of 4, suspended biomass of 3 to 3.5 g/L, HRT of 10 h, and DO of 1.5 to 2.5 mg/L. Scanning electron microscopy (SEM) of suspended and attached biofilm showed a dense structure of coccus and bacillus bacteria with the diameter ranging from 0.3 to 1.2 ?m. The Fourier transform infrared (FTIR) spectroscopy results indicated phosphorylated macromolecules and carbohydrates mix or bind with extracellular proteins in exopolysaccharides. © IWA Publishing 2018.
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    Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2 nanocomposite: a comparative study with solar and UV photocatalysis
    (Springer Verlag service@springer.de, 2018) Kalikeri, S.; Kamath, N.; Gadgil, D.J.; Shetty K, V.
    Polyaniline-TiO2 (PANI-TiO2) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO2. The PANI-TiO2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Solar light-driven photocatalysis using mixed-phase bismuth ferrite (BiFeO3/Bi25FeO40) nanoparticles for remediation of dye-contaminated water: kinetics and comparison with artificial UV and visible light-mediated photocatalysis
    (Springer Verlag service@springer.de, 2018) Kalikeri, S.; Shetty K, V.
    Mixed-phase bismuth ferrite (BFO) nanoparticles were prepared by co-precipitation method using potassium hydroxide as the precipitant. X-ray diffractogram (XRD) of the particles showed the formation of mixed-phase BFO nanoparticles containing BiFeO3/Bi25FeO40 phases with the crystallite size of 70 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of quasi-spherical particles. The BFO nanoparticles were uniform sized with narrow size range and with the average hydrodynamic diameter of 76 nm. The band gap energy of 2.2 eV showed its ability to absorb light even in the visible range. Water contaminated with Acid Yellow (AY-17) and Reactive Blue (RB-19) dye was treated by photocatalysis under UV, visible, and solar light irradiation using the BFO nanoparticles. The BFO nanoparticles showed maximum photocatalytical activity under solar light as compared to UV and visible irradiations, and photocatalysis was favored under acidic pH. Complete degradation of AY-17 dyes and around 95% degradation of RB-19 could be achieved under solar light at pH 5. The kinetics of degradation followed the Langmuir–Hinshelhood kinetic model showing that the heterogeneous photocatalysis is adsorption controlled. The findings of this work prove the synthesized BFO nanoparticles as promising photocatalysts for the treatment of dye-contaminated industrial wastewater. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Computational investigation of air solid flow in a spray dryer for effluent treatment
    (Scientific Publishers, 2020) Singh, S.K.; Ali, B.
    In this work, the hydrodynamics and evaporation rate of the co-current spray dryer is numerically investigated through ANSYS Fluent (CFD). The performance of the spray dryer depends on the geometry, operating conditions, and underlying hydrodynamics in such systems. To predict the air-solid flow in a spray dryer, the Euler-Lagrangian CFD model is used to track the particles in the dryer. The continuous phase turbulence is predicted using RNG version of k-turbulence model. To quantify the flow pattern, a horizontal line is considered and spatial variation of velocity profiles are analyzed. The predicted air velocity variation was found to be maximum at the center of the core. Further, the airflow pattern is analyzed for various operating temperatures and feed properties. It was found that airflow pattern influences particle behavior with minimum deposition rates on each section of the wall when air temperature is 350 K. © 2020 Scientific Publishers. All rights reserved.
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    Computational investigation of hydrodynamics and drying of industrial sludge waste in a spouted bed column
    (Scientific Publishers, 2020) Santhosh Kumar, N.; Ali, B.
    The disposal of sludge from waste water treatment plants adversely affects the environment. Since sludge wastes are sticky, drying of such waste water sludge is challenging. Conventionally, these sludges are dried in open spaces where a large area of land is required which is a time-consuming process. To overcome this, spouted bed is used in the present investigation. The spouted bed is a gas-solid contactor for handling coarse particles of size greater than 1 mm with low operating pressure. In this work, hydrodynamics of waste water sludge in a conventional spouted bed is numerically investigated using Computational Fluid Dynamics (CFD). Euler-Eulerian CFD model is used to study the flow pattern in such system. The continuous phase turbulence (air) is modeled using standard - model. The spouting height and solid circulation rate are calculated to analyze spouting behavior. This is compared with a draft tube spouted bed system and found that the draft tube supports in enhancing the spouting characteristics of the bed. Further, an optimum draft tube configuration is found that promotes solid circulation rate. The drying characteristics are analyzed for various operating conditions and found that the temperature of air significantly improves the rate of drying. © 2020 Scientific Publishers. All rights reserved.