Browsing by Author "Shetty K, K.V."

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Artificial neural networks model for the prediction of steady state phenol biodegradation in a pulsed plate bioreactor
(2008) Shetty K, K.V.; Nandennavar, S.; Srinikethan, G.
Background: A recent innovation in fixed film bioreactors is the pulsed plate bioreactor (PPBR) with immobilized cells. The successful development of a theoretical model for this reactor relies on the knowledge of several parameters, which may vary with the process conditions. It may also be a time-consuming and costly task because of their nonlinear nature. Artificial neural networks (ANN) offer the potential of a generic approach to the modeling of nonlinear systems. Results: A feedforward ANN based model for the prediction of steady state percentage degradation of phenol in a PPBR by immobilized cells of Nocardia hydrocarbonoxydans (NCIM 2386) during continuous biodegradation has been developed to correlate the steady state percentage degradation with the flow rate, influent phenol concentration and vibrational velocity (amplitude x frequency). The model used two hidden layers and 53 parameters (weights and biases). The network model was then compared with a Multiple Regression Analysis (MRA) model, derived from the same training data. Further these two models were used to predict the percentage degradation of phenol for blind test data. Conclusions: The performance of the ANN model was superior to that of the MRA model and was found to be an efficient data-driven tool to predict the performance of a PPBR for phenol biodegradation. © 2008 Society of Chemical Industry.
Biofibres from biofuel industrial byproduct—Pongamia pinnata seed hull
(Springer Science and Business Media Deutschland GmbH, 2017) Manjula, P.; Srinikethan, G.; Shetty K, K.V.
Background: Biodiesel production using Pongamia pinnata (P. pinnata) seeds results in large amount of unused seed hull. These seed hulls serve as a potential source for cellulose fibres which can be exploited as reinforcement in composites. Methods: These seed hulls were processed using chlorination and alkaline extraction process in order to isolate cellulose fibres. Scanning electron microscopy (SEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis demonstrated the morphological changes in the fibre structure. Results: Cellulose microfibres of diameter 6–8 µm, hydrodynamic diameter of 58.4 nm and length of 535 nm were isolated. Thermal stability was enhanced by 70 °C and crystallinity index (CI) by 19.8% ensuring isolation of crystalline cellulose fibres. Conclusion: The sequential chlorination and alkaline treatment stemmed to the isolation of cellulose fibres from P. pinnata seed hull. The isolated cellulose fibres possessed enhanced morphological, thermal, and crystalline properties in comparison with P. pinnata seed hull. These cellulose microfibres may potentially find application as biofillers in biodegradable composites by augmenting their properties. © 2017, The Author(s).
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.
Characteristics of a novel Acinetobacter sp. and its kinetics in hexavalent chromium bioreduction
(2012) Narayani, M.; Shetty K, K.V.
Cr-B2, a Gram-uegadve hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr-B2 exhibited a resistance for 1,100mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as Ni2+ (800 mg/l), Cu2+ (600 mg/l), Pb2+ (1,100 mg/l), Cd2+ (350 mg/l), Zn2+ (700 mg/l), and Fe3+ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The Km values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. Vmax values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp. © The Korean Society for Microbiology and Biotechnology.
Combined effect of plate pulsation parameters and phenol concentrations on the phenol removal efficiency of a pulsed plate bioreactor with immobilized cells
(2008) Shetty K, K.V.; Kedargol, M.R.; Srinikethan, G.
Continuous aerobic biodegradation of phenol in synthetic wastewater with phenol at different concentrations (200, 300, 500, 800 and 900 ppm) was carried out in a pulsed plate column, which is used as a bioreactor with immobilised cells of Nocardia hydrocarbonoxydans (NCIM 2386) at a dilution rate of 0.4094 h-1 and amplitude of 4.7 cm at various frequencies of pulsation (0, 0.25, 0.5, 0.75 and 1 s-1). The effect of frequency of pulsation on the steady state performance of the bioreactor for phenol biodegradation at different influent concentrations was studied. Percentage degradations were observed to be a combined effect of volumetric phenol loading, reactor residence time, mass transfer limitations and phenol inhibition effect. At 500 ppm influent phenol concentration the effect of frequencies of pulsation on the steady state percentage degradation at different amplitudes was studied. The percentage degradation increased with increase in frequency and almost 100% degradation was achieved at 0.75s-1, 0.5s-1 or 0.25s -1, with 3.3, 4.7 or 6.0 cm amplitudes respectively and hence the vibrational velocity (amplitude * frequency) was found to influence the steady state performance of the reactor. It was found that optimum vibrational velocities need to be fixed for maximum removal efficiency of the bioreactor depending on the influent phenol concentration. © IWA publishing 2008.
Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation by immobilized Pseudomonas desmolyticum cells in a pulsed plate bioreactor
(Higher Education Press, 2016) Rangappa, V.B.; Shetty K, K.V.; Bharthaiyengar, S.M.
Pulsed plate bioreactor (PPBR) is a biofilm reactor which has been proven to be very efficient in phenol biodegradation. The present paper reports the studies on the effect of dilution rate on the physical, chemical and morphological characteristics of biofilms formed by the cells of Pseudomonas desmolyticum on granular activated carbon (GAC) in PPBR during biodegradation of phenol. The percentage degradation of phenol decreased from 99% to 73% with an increase in dilution rate from 0.33 h–1 to 0.99 h–1 showing that residence time in the reactor governs the phenol removal efficiency rather than the external mass transfer limitations. Lower dilution rates favor higher production of biomass, extracellular polymeric substances (EPS) as well as the protein, carbohydrate and humic substances content of EPS. Increase in dilution rate leads to decrease in biofilm thickness, biofilm dry density, and attached dry biomass, transforming the biofilm from dense, smooth compact structure to a rough and patchy structure. Thus, the performance of PPBR in terms of dynamic and steady-state biofilm characteristics associated with phenol biodegradation is a strong function of dilution rate. Operation of PPBR at lower dilution rates is recommended for continuous biological treatment of wastewaters for phenol removal. [Figure not available: see fulltext.] © 2016, Higher Education Press and Springer-Verlag Berlin Heidelberg.
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.
Highly stable silver nanoparticles synthesized using Terminalia catappa leaves as antibacterial agent and colorimetric mercury sensor
(Elsevier B.V., 2017) Devadiga, A.; Shetty K, K.V.; Saidutta, M.B.
Silver nanoparticles (AgNPs) were synthesized using the aqueous extract of an agrowaste: Terminalia catappa leaves. The AgNPs were characterized using UV–VIS spectroscopy, Transmission electron microscopy, Scanning electron microscopy, Fourier Transmission Infrared spectroscopy and Dynamic light scattering analysis. AgNPs were monodispersed, crystalline, quasi-spherical with average size of ?11 nm and were encapsulated with capping agents present in the extract. The AgNPs were stable with the zeta potential value of ?36.7 mV. These AgNPs exhibited significant antibacterial activity against water borne pathogens and could be used as colorimetric sensors for the detection of trace levels of mercury, indicating their multifaceted application in antibacterial coating, water treatment and as colorimetric mercury sensors. The overall synthesis process emphasizes on the agrowaste utilization for the “green” synthesis of AgNPs. © 2017 Elsevier B.V.
Isotherm, kinetics, and process optimization for removal of Remazol Brilliant Blue dye from contaminated water using adsorption on acid-treated red mud
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ratnamala, G.M.; Shetty K, K.V.; Srinikethan, G.
Red mud, which is a waste product from alumina production, has been utilized after activation with concentrated sulphuric acid treatment for removal of Remazol Brilliant Blue (RBB) dye from dye-contaminated water to investigate its potential as a low-cost adsorbent. The activation has enhanced the surface area of red mud from 20.2 to 32.28 m2/g, thus enhancing its adsorption capacity. The effect of initial dye concentration, contact time, initial pH and adsorbent dosage on percentage removal of dye using concentrated sulphuric acid-treated red mud (CATRM) was investigated. The ranges of these variables for optimization were selected based on batch studies. Acidic pH favoured adsorption and 300 min contact time was found to be suitable for attainment of equilibrium under shaking conditions of 145 rpm. Langmuir isotherm model has been found to represent the equilibrium data for RBB-CATRM adsorption system better in comparison with Freundlich model. The adsorption capacity of CATRM was found to increase with the increase in temperature, and at 40°C, it was found to be 125 mg dye/g of CATRM. The adsorption kinetics was represented by second-order kinetic model, and the kinetic constant was estimated to be 0.0063 g/mg min. Factors affecting the adsorption process were optimized by response surface methodology based on experiments designed as per central composite design. The effects of individual variables and their interaction effects on dye removal were determined. The results of the study showed that dye removal efficiency of almost 100% can be obtained with optimal conditions of initial dye concentration at 105 mg/l, red mud dosage of 2.05 g/l, initial pH of 1 and temperature of 31.65°C. pH and temperature were found to have high interaction effect on adsorption. © 2015 Balaban Desalination Publications. All rights reserved.
Kinetics of bioreduction of hexavalent chromium by poly vinyl alcohol-alginate immobilized cells of Ochrobactrum sp. Cr-B4 and comparison with free cells
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Hora, A.; Shetty K, K.V.
The cells of Ochrobactrum sp. Cr-B4 immobilized in PVA-alginate blended matrix could be successfully used for bioreduction of Cr(VI) from contaminated water. The removal mechanism included adsorption on solid-liquid interface and enzyme catalyzed chromate reduction. At lower concentrations the initial rate of Cr(VI) reduction with immobilized cells was found to be slightly higher than that of free cells owing to adsorption on the immobilization matrix. But after a certain time the rate of Cr(VI) reduction by free and immobilized cells was similar. The estimation of effectiveness factor (?), indicated that there were no diffusional limitations offered by the immobilization of Cr-B4 as the value of ? was fond to be near “one” at different concentrations of Cr(VI). The kinetic analysis showed that both free and immobilized cells followed Michaelis–Menten kinetics with Kmand Vmaxof 456.1 mg/L and 14.67 mg/L/h for free cells respectively; 499.4 mg/L and 15.32 mg/L/h for immobilized cells respectively. The kinetic characteristics of Cr(VI) reduction were not altered by immobilization. This study reveals the potential applications of immobilized Cr-B4 in development of industrially feasible and economically viable bioremediation strategy for discharging Cr(VI) free effluent into the environment. © 2015 Balaban Desalination Publications. All rights reserved.
Microbial disinfection of water with endotoxin degradation by photocatalysis using Ag@TiO2 core shell nanoparticles
(Springer Verlag service@springer.de, 2016) Sreeja, S.; Shetty K, K.V.
The studies on photocatalytic disinfection of water contaminated with Escherichia coli using Ag core and TiO2 shell (Ag@TiO2) nanoparticles under UV irradiation showed that these nanoparticles are very efficient in water disinfection both in their free and immobilised form. Complete disinfection of 40 × 108 CFU/mL could be achieved in 60 min with 0.4 g/L catalyst loading and in 35 min with 1 g/L catalyst loading. Ag@TiO2 nanoparticles were found to be superior to TiO2 nanoparticles in photocatalytic disinfection of water. Kinetics of disinfection followed Chick’s law, and the pseudo-first-order rate constant was 0.0168 min?1 for a catalyst loading of 0.1 g/L. Disinfection of water and degradation of endotoxins (harmful disinfection residual) occurred simultaneously during photocatalysis thereby making the treated water safe for use. Endotoxin degradation showed a shifting order of kinetics. The rate of photocatalysis with nanoparticles immobilised in cellulose acetate film was marginally lower as compared to that of free nanoparticles. Negligible Ag ion leakage and re-growth of cells post-photo-catalytic treatment of water confirmed that complete disintegration of E. coli occurred during photocatalysis making the treated water safe for use. Therefore, Ag@TiO2 nanoparticles have a potential for large-scale application in drinking water treatment plants and household purification units. © 2016, Springer-Verlag Berlin Heidelberg.
Modeling and genetic algorithm-based multi-objective optimization of the MED-TVC desalination system
(2012) Janghorban Esfahani, I.; Ataei, A.; Shetty K, K.V.; Oh, T.; Park, J.H.; Yoo, C.
This study proposes a systematic approach of analysis and optimization of the multi-effect distillation-thermal vapor compression (MED-TVC) desalination system. The effect of input variables, such as temperature difference, motive steam mass flow rate, and preheated feed water temperature was investigated using response surface methodology (RSM) and partial least squares (PLS) technique. Mathematical and economical models with exergy analysis were used for total annual cost (TAC), gain output ratio (GOR) and fresh water flow rate (Q). Multi-objective optimization (MOO) to minimize TAC and maximize GOR and Q was performed using a genetic algorithm (GA) based on an artificial neural network (ANN) model. Best Pareto optimal solution selected from the Pareto sets showed that the MED-TVC system with 6 effects is the best system among the systems with 3, 4, 5 and 6 effects, which has a minimum value of unit product cost (UPC) and maximum values of GOR and Q. The system with 6 effects under the optimum operation conditions can save 14%, 12.5%, 2% in cost and reduces the amount of steam used for the production of 1m 3 of fresh water by 50%, 34% and 18% as compared to systems with 3, 4 and 5 effects, respectively. © 2012 Elsevier B.V..
Oxygen mass transfer coefficients in a three-phase pulsed plate bioreactor
(Berkeley Electronic Press, 2010) Shetty K, K.V.; Srinikethan, G.
Volumetric oxygen mass transfer coefficient is a decisive parameter for the selection of any contactor as an aerobic bioreactor. A pulsed plate column with fixed bed of solids in interplate spaces is a recent innovation in the field of immobilized cell bioreactors. Volumetric oxygen mass transfer coefficients are determined in a three-phase pulsed plate column involving air and water phases and with a fixed bed of glass particles, which can serve as a surface for cell immobilization packed in the interplate spaces. The volumetric mass transfer coefficients obtained in this column range from 0.067 to 0.1495 s-1la with these variables was developed. The volumetric oxygen mass transfer coefficient values in the three-phase pulsed plate column are found to be similar or higher than the literature reported values for conventional two-phase pulsed plate columns. The values of volumetric oxygen mass transfer coefficients in the three-phase pulsed plate column are of higher order of magnitude than the literature reported values of volumetric oxygen mass transfer coefficient for many other three-phase gas-liquid-solid reactors. The pulsed plate column with fixed bed of solids is proven to have all the potential to be used as an aerobic bioreactor with immobilized cells due to its better gas-liquid mass transfer characteristics. Copyright © 2010 The Berkeley Electronic Press. All rights reserved.
Pathway identification, enzyme activity and kinetic study for the biodegradation of phenol by Nocardia hydrocarbonoxydans NCIM 2386
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Shetty, G.R.; Shetty K, K.V.
Nocardia hydrocarbonoxydans NCIM 2386 (Nhy) can grow using phenol as a sole carbon source and has a strong ability to degrade phenol. The paper presents the main metabolism pathways and mechanism of phenol degradation by Nhy. Phenol was found to be degraded via meta cleavage of catechol by the action of enzyme catechol 2,3-dioxygenase. The enzyme was found to be both extracellular and cell bound. The cell bound and extracellular enzymes actively degraded phenol even in the absence of the organism. The rate of phenol degradation by extracellular enzymes as sole enzymatic process (in the absence of cells) was found to be almost similar to that with the whole cells, indicating the prominence of extracellular enzymes. Michaelis–Menten model was found to fit the degradation rate kinetics of total phenol for total phenol concentrations of less than 100 mg L?1and also the degradation rate kinetics of catechol at catechol concentrations of less than 80 mg L?1during the exponential growth phase of the organism. Michaelis– Menten model was found to fit the kinetics of catechol formation rate which is also equal to the actual rate of phenol degradation to catechol. Both phenol and catechol were found to be substrate inhibitory. © 2015 Balaban Desalination Publications. All rights reserved.
Performance of pulsed plate bioreactor for biodegradation of phenol
(2007) Shetty K, K.V.; Kalifathulla, I.; Srinikethan, G.
Biodegradation of phenol was carried out using Nocardia hydrocarbonoxydans immobilised on glass beads, in a pulsed plate bioreactor. The effect of operating parameters like frequency of pulsation and amplitude of pulsation on the performance of pulsed plate bioreactor for biodegradation of phenol in a synthetic wastewater containing 500 ppm phenol was studied. Axial concentration profile measurements revealed that the pulsed plate bioreactor shows continuous stirred tank behaviour. As the amplitude was increased, percentage degradation increased, reaching 100% at amplitude of 4.7 cm and higher. Introduction of pulsation is found to increase the percentage degradation. Percentage degradation has increased with increase in frequency and 100% degradation was achieved at 0.5 s-1 and above. Biofilms developed in a non-pulsed bioreactor were thicker than those in the pulsed plate bioreactor. But biofilm thickness remained almost constant with increasing frequency. Biofilm density was found to be influenced by pulsation. The time required to reach steady state was more for pulsed reactor than the non-pulsed reactor and this start-up time had increased with increase in frequency of pulsation. The performance studies reveal that the pulsed plate bioreactor with immobilized cells has the potential to be an efficient bioreactor for wastewater treatment. © 2006 Elsevier B.V. All rights reserved.
Photocatalytic degradation of phenol using Ag core-TiO2 shell (Ag@TiO2) nanoparticles under UV light irradiation
(Springer Verlag service@springer.de, 2016) Shet, A.; Shetty K, K.V.
Ag@TiO2 nanoparticles were synthesized by one pot synthesis method with postcalcination. These nanoparticles were tested for their photocatalytic efficacies in degradation of phenol both in free and immobilized forms under UV light irradiation through batch experiments. Ag@TiO2 nanoparticles were found to be the effective photocatalysts for degradation of phenol. The effects of factors such as pH, initial phenol concentration, and catalyst loading on phenol degradation were evaluated, and these factors were found to influence the process efficiency. The optimum values of these factors were determined to maximize the phenol degradation. The efficacy of the nanoparticles immobilized on cellulose acetate film was inferior to that of free nanoparticles in UV photocatalysis due to light penetration problem and diffusional limitations. The performance of fluidized bed photocatalytic reactor operated under batch with recycle mode was evaluated for UV photocatalysis with immobilized Ag@TiO2 nanoparticles. In the fluidized bed reactor, the percentage degradation of phenol was found to increase with the increase in catalyst loading. © 2015, Springer-Verlag Berlin Heidelberg.
Removal of remazol brilliant blue dye from dye-contaminated water by adsorption using red mud: Equilibrium, kinetic, and thermodynamic studies
(2012) Ratnamala, G.M.; Shetty K, K.V.; Srinikethan, G.
Utilization of industrial solid wastes for the treatment of wastewater from another industry could help environmental pollution abatement, in solving both solid waste disposal as well as liquid waste problems. Red mud (RM) is a waste product in the production of alumina and it poses serious pollution hazard. The present paper focuses on the possibility of utilization of RM as an adsorbent for removal of Remazol Brilliant Blue dye (RBB), a reactive dye from dye-contaminated water. Adsorption of RBB, from dye-contaminated water was studied by adsorption on powdered sulfuric acid-treated RM. The effect of initial dye concentration, contact time, initial pH, and adsorbent dosage were studied. Langmuir isotherm model has been found to represent the equilibrium data for RBB-RM adsorption system better than Freundlich model. The adsorption capacity of RM was found to be 27.8 mg dye/g of adsorbent at 40 °C. Thermodynamic analysis showed that adsorption of RBB on acid-treated RM is an endothermic reaction with ?H0 of 28.38 kJ/mol. The adsorption kinetics is represented by second-order kinetic model and the kinetic constant was estimated to be 0.0105 ± 0.005 g/mgmin. Validity of intra-particle diffusion kinetic model suggested that among the mass transfer processes during the dye adsorption process, pore diffusion is the controlling step and not the film diffusion. The process can serve dual purposes of utilization of an industrial solid waste and the treatment of liquid waste. © Springer Science+Business Media Dordrecht 2012.
Shear stress effects on production of exopolymeric substances and biofilm characteristics during phenol biodegradation by immobilized Pseudomonas desmolyticum (NCIM2112) cells in a pulsed plate bioreactor
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Veena, B.R.; Shetty K, K.V.; Saidutta, M.B.
This article reports studies on a continuous pulsed plate bioreactor (PPBR) with the cells of Pseudomonas desmolyticum (NCIM2112) immobilized on granular activated carbon (GAC) used as a biofilm reactor for biodegradation of phenol. Almost complete removal of 200 ppm phenol could be achieved in this bioreactor. Biofilm structure and characteristics are influenced by hydrodynamic and shear conditions in bioreactors. In this article, the effect of shear stress induced by frequency of pulsation on biofilm characteristics during the startup period in the PPBR is reported. The startup time decreased with the increase in frequency of pulsation. The formation of biofilm in PPBR was found to have three phases: accumulation, compaction, and plateau. The effect of frequency on production of exoploymeric substances (EPS) such as, protein, carbohydrate, and humic substance is reported. An increase in shear stress induced by the frequency of pulsation increased the production of exopolymeric substances in the biofilm during startup of the bioreactor. Increase in shear stress caused a decrease in biofilm thickness and an increase in dry density of the biofilm. Increase in shear stress resulted in a smoother and thinner biofilm surface with more compact and dense structure. © 2016, Copyright © Taylor & Francis Group, LLC.
Simultaneous adsorption of Remazol brilliant blue and Disperse orange dyes on red mud and isotherms for the mixed dye system
(Springer Verlag service@springer.de, 2017) Ratnamala, R.; Shetty K, K.V.; Srinikethan, G.
The paper presents the adsorption of Remazol brilliant blue (RBB) and Disperse orange 25 (DO25) dyes from aqueous solution of the mixture of dyes onto concentrated sulphuric acid-treated red mud (ATRM). First-order derivative spectrophotometric method was developed for the analysis of RBB and DO25 in mixed dye aqueous solution to overcome the limitations arising due to interference in the zero-order spectral method. The optimum conditions to maximize RBB adsorption favoured the adsorption of RBB, and those for DO25 favoured DO25 adsorption from the mixed dye aqueous solutions. Presence of a second dye always inhibited the adsorption of a target dye. The uptake and percentage adsorption of each of the dyes onto ATRM from the aqueous solution of the mixture of dyes decreased considerably with increasing concentrations of the other dye showing the antagonistic effect. Monocomponent Langmuir isotherm fitted the mixed dye adsorption equilibrium data better than the monocomponent Freundlich isotherm. However, monocomponent models are suitable for the fixed concentration of the other dye. Modified Langmuir isotherm model adequately predicted the multi-component adsorption equilibrium data for RBB-DO25-ATRM adsorption system with a good accuracy and is more generic from the application point of view. © 2017, Springer-Verlag Berlin Heidelberg.
Solar light mediated photocatalytic degradation of phenol using Ag core - TiO2 shell (Ag@TiO2) nanoparticles in batch and fluidized bed reactor
(Elsevier Ltd, 2016) Shet, A.; Shetty K, K.V.
Ag@TiO2 nanoparticles were synthesised using one pot method followed by calcination at 450 °C for 3 h and were tested for their photocatalytic efficacy in degradation of phenol both in free and immobilized form under solar light irradiation through batch experiments. Ag@TiO2 nanoparticles were found to be effective in solar photocatalytic degradation of phenol. The effect of factors such as pH, initial phenol concentration and catalyst loading on phenol degradation were evaluated and these factors were found to influence the process efficiency. The optimum values of these factors were determined to maximize the phenol degradation. The efficacy of nanoparticles immobilized on cellulose acetate film was inferior to that of free nanoparticles in solar photocatalysis due to light penetration problem and diffusional limitations. The performance of fluidized bed photocatalytic reactor operated under batch with recycle mode for solar photocatalysis of phenol with immobilized Ag@TiO2 nanoparticles was evaluated for large scale application. The performance was found to be dependent on catalyst loading and the optimum is governed by active catalyst sites and light penetration limitations. The photocatalytic degradation of phenol by Ag@TiO2 nanoparticles was only marginally influenced by the presence of small traces of chloride ions. Ag@TiO2 showed a better efficacy as solar photocatalyst than as UV photocatalyst in degradation of phenol. Solar light irradiation is recommended because solar energy, a readily available form of energy can be effectively harnessed for energy efficient, environment friendly and cost effective process. The kinetics of degradation of phenol was found to follow the nth order kinetics with order, n = 2.19 for solar photocatalysis. © 2016 Elsevier Ltd.