Browsing by Author "Murthy, D.V.R."

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Adsorption of phenol on granular activated carbon from nutrient medium: Equilibrium and kinetic Study
(2009) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.
This paper presents the adsorption of phenol on granular activated carbon (GAC) from nutrient medium suitable for microorganisms' growth and also the subsequent biodegradation. Two parameter Langmuir and Freundlich adsorption isotherm models were studied using large range of phenol concentration (50-1000 mg/L). In low range of phenol concentration (50-300 mg/L), correlation coefficient, normalized deviation "g% and separation factor were 0.9989,2.18% and 0.38-0.78 respectively, while for higher concentration range (400-1000 mg/L), the corresponding values were 0.9719, 1.9% and 0.45- 0.67. Freundlich isotherm gave correlation coefficient of 0.9984, 1/n. value of 0.7269 and normalized deviation of 4.55%. Comparison based on R2, adjusted R2, normalized deviation and root mean square deviation (RMSD) showed that the Redke-Prausnitz isotherm model gives better prediction compared to other models. Adsorption of phenol follows pseudo second order kinetics with correlation coefficient closer to one. Biodegradation study using immobilized cells of Nocardia hydrocarbonoxydans on GAC showed that, biodegradation begins well before GAC reaches the saturation period.
An analytical model for spiral wound Reverse Osmosis membrane modules: Part I - Model development and parameter estimation
(2011) Sundaramoorthy, S.; Srinivasan, G.; Murthy, D.V.R.
A mathematical model for spiral wound Reverse Osmosis membrane module is presented in this work. The model incorporates spatial variations of pressure, flow and solute concentration in the feed channel and uniform conditions of pressure in the permeate channel. Assuming solution-diffusion model to be valid, explicit analytical equations were derived for spatial variations of pressure, flow, solvent flux and solute concentration on the feed channel side of the module. Analytical procedures for estimation of model parameters were presented. Graphical linear fit methods were developed for estimation of parameters Aw (solvent transport coefficient), Bs (solute transport coefficient) and b (feed channel friction parameter). The mass transfer coefficient k was assumed to vary along the length of the feed channel with varying conditions of flow, solute concentration and pressure. Explicit analytical equations for estimation of mass transfer coefficient were presented. In this paper (Part I), theoretical studies on development of mathematical model and methods for estimation of model parameters are presented. In Part II of this paper series [1], Studies on validation of this model with experimental data are presented. The studies cover experimental work on a spiral wound RO module with an organic compound namely chlorophenol as a solute. © 2011 Elsevier B.V.
An analytical model for spiral wound reverse osmosis membrane modules: Part II - Experimental validation
(2011) Sundaramoorthy, S.; Srinivasan, G.; Murthy, D.V.R.
This paper presents the experimental studies carried out for validation of a new mathematical model [1] developed for predicting the performance of spiral wound RO modules. Experiments were conducted on a laboratory scale spiral wound RO module taking chlorophenol as a model solute. Experiments were carried out by varying feed flow rate, feed concentration and feed pressure and recording the readings of permeate concentration, retentate flow rate, retentate concentration and retentate pressure. A total of 73 experimental readings were recorded. The membrane transport parameters Aw (solvent transport coefficient) and Bs (solute transport coefficient) and the feed channel friction parameter b were estimated by a graphical technique developed in this work. The mass transfer coefficient k, estimated using the experimental data, was found to be strongly influenced by solvent flux and solute concentration apart from the fluid velocity. Taking the effects of solvent flux, solute concentration and fluid velocity, a new mass transfer correlation for Sherwood number is proposed in this work for the estimation of mass transfer coefficient. Comparison of model predictions with experimental observations demonstrated that the model was capable of predicting permeate concentration within 10% error, retentate rate flow within 4% error and rejection coefficient within 5% error. © 2011 Elsevier B.V.
Continuous phenol removal using Nocardia hydrocarbonoxydans in spouted bed contactor: Shock load study
(2009) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.
Shock load studies are essential to investigate the suitability of biocontactors in degradation of pollutants. In the present work, the degradation of phenol by immobilized Nocardia hydrocarbonoxydans in a spouted bed contactor was conducted. Granular activated carbon (GAC) and polymer beads were tested for the immobilization of cells of N. hydrocarbonoxydans-NCIM 2386. Initially, batch immobilization study was conducted to know the quantity of immobilized microorganisms per gram of solids and then the immobilized solids were used in the spouted bed contactor for phenol degradation. Also, the shock loading of phenol and hydraulic shock load test was performed to check the stability of operation. The immobilized Nocardia cells sustained the shock load and hydraulic load of phenol. Increase of influent phenol concentration and dilution rates increased the steady state effluent phenol concentration. Almost 95% degradation at maximum phenol loading of 0.73 gL-1h-1 was achieved. GAC has more attached biomass weight compared to polymer beads. © 2009 Academic Journals.
Drying of Agricultural Grains in a Multiple Porous Draft Tube Spouted Bed
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2017) Rajashekhara, S.; Murthy, D.V.R.
A multiple porous draft tube spouted bed (MPDTSB) was used to carry out drying of Ragi (Eleusine coracana), Barley, and Wheat grains. Batch experiments were conducted under varied conditions of initial moisture contents of grains, air inlet temperatures, and airflow rates. The draft tube parameters and fluid inlet sizes were also varied in the study. The results indicated that MPDTSB has the potential to be used for scale up to large-scale solids drying. In addition, two single porous draft tube spouted beds (SPDTSBs) were used for comparison with MPDTSB; the batch drying times in the MPDTSB were found to be lower when compared to those in SPDTSB under identical operating conditions. © 2017, Copyright © Taylor & Francis Group, LLC.
Enhanced degradation of azo dye using mixed cultures of white-rot fungi in a modified rotating packed disc bioreactor and reuse of treated water
(Elsevier Ltd, 2023) Kalnake, R.P.; Raval, R.; Murthy, D.V.R.; Vanzara, P.B.; Raval, K.
Reactive azo dyes are toxic and carcinogenic. In this study, mixed cultures of white-rot fungi (WRF) are used to treat synthetic reactive black 5 (RB-5) wastewater in a modified rotating packed disc bioreactor (RPDB). The continuous degradation studies were carried out for 25 days under the influence of the recycle stream in which 3665 L of synthetic effluent was treated. The dye wastewater was completely decolorized with more than 93 % chemical oxygen demand (COD) reduction using the mixed fungal culture. During the continuous operation, the COD of influent reduced more than 85 % for successive 25 days of continuous operation at hydraulic retention time of 10.8 h. The dry biomass loading was about 0.14 g/g GAC at the end of the continuous process. The rate of COD removal followed first order kinetics with a rate constant of 0.026 per hour. The treated water was reused to produce melanin from microbial culture. © 2023 Elsevier Ltd
Minimum superficial fluid velocity in a gas-solid swirled fluidized bed
(2010) Harish Kumar, S.; Murthy, D.V.R.
A swirl flow is achieved in a bed of solids by passing air through multiple fluid inlets, which are tangentially located at the base of a flat-based circular column. The minimum superficial velocities needed to achieve swirling of the bed are measured experimentally under varied conditions. An empirical correlation for the minimum swirl velocity has been proposed. The results indicate that a stable swirling regime operation of the bed is possible. There exists an upper limit of static bed depth beyond which stable swirling of entire bed is not possible. The minimum swirl velocities are found to be 1.2-1.3 times the minimum fluidization velocities predicted for conventional fluidized beds. © 2010 Elsevier B.V.
Modeling of phenol degradation in spouted bed contactor using artificial neural network (ANN)
(2008) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.
Presence of phenol and phenolic compounds in various wastewaters and its harmful effects has led to the use of different treatment methods. Work on biological methods shows the use of different microorganisms and different bioreactors so as to improve the removal efficiency economically. The present work deals with the use of N. hydrocarbonoxydans (NCIM 2386), an actinomycetes, for the degradation of phenol. N. hydrocarbonoxydans was immobilized on GAC and used in a spouted bed contactor for effective contact of microorganisms and the substrate. The contactor performance was studied by varying flow rates, influent concentrations and the solids loading in the contactor. The effect of these variables on phenol degradation was investigated and modeling study was carried out using the artificial neural network (ANN). A feed forward neural network with back propagation was used for the model development. The experiments were planned as per the face centered cube design (FCCD) and used for training of the model, whereas data from four other experimental runs were used for testing and validation of the model. The network was optimized for the number of neurons based on the mean square error. The ANN model with three layers with three input neurons, eight neurons in hidden layers and one output neuron was found to predict effectively the effluent concentration for the given operating conditions in the spouted bed contactor. The mean square error was found to be 9.318e-12 for this ANN model. Also the experimental data was used to develop second order nonlinear empirical model obtained using multiple regression (MR) and the results compared with ANN using correlation coefficient (R2), average absolute error (AAE) and root mean square error (RMSE). Results show that R2, AAE and RMSE values of MR model were 0.9363, 2.085 % and 2.338 % respectively, while in case of ANN model these values were 0.9995, 0.59 % and 1.263 % respectively. This shows that ANN model prediction is better than multiple regression model prediction. Copyright � 2008 The Berkeley Electronic Press. All rights reserved.
Modeling of phenol degradation in spouted bed contactor using artificial neural network (ANN)
(Walter de Gruyter GmbH, 2008) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.
Presence of phenol and phenolic compounds in various wastewaters and its harmful effects has led to the use of different treatment methods. Work on biological methods shows the use of different microorganisms and different bioreactors so as to improve the removal efficiency economically. The present work deals with the use of N. hydrocarbonoxydans (NCIM 2386), an actinomycetes, for the degradation of phenol. N. hydrocarbonoxydans was immobilized on GAC and used in a spouted bed contactor for effective contact of microorganisms and the substrate. The contactor performance was studied by varying flow rates, influent concentrations and the solids loading in the contactor. The effect of these variables on phenol degradation was investigated and modeling study was carried out using the artificial neural network (ANN). A feed forward neural network with back propagation was used for the model development. The experiments were planned as per the face centered cube design (FCCD) and used for training of the model, whereas data from four other experimental runs were used for testing and validation of the model. The network was optimized for the number of neurons based on the mean square error. The ANN model with three layers with three input neurons, eight neurons in hidden layers and one output neuron was found to predict effectively the effluent concentration for the given operating conditions in the spouted bed contactor. The mean square error was found to be 9.318e-12 for this ANN model. Also the experimental data was used to develop second order nonlinear empirical model obtained using multiple regression (MR) and the results compared with ANN using correlation coefficient (R2), average absolute error (AAE) and root mean square error (RMSE). Results show that R2, AAE and RMSE values of MR model were 0.9363, 2.085 % and 2.338 % respectively, while in case of ANN model these values were 0.9995, 0.59 % and 1.263 % respectively. This shows that ANN model prediction is better than multiple regression model prediction. Copyright Â© 2008 The Berkeley Electronic Press. All rights reserved.
Reprint of: “An analytical model for spiral wound reverse osmosis membrane modules: Part II — Experimental validation”
(Elsevier B.V., 2011) Sundaramoorthy, S.; Srinivasan, G.; Murthy, D.V.R.
This paper presents the experimental studies carried out for validation of a new mathematical model [1] developed for predicting the performance of spiral wound RO modules. Experiments were conducted on a laboratory scale spiral wound RO module taking chlorophenol as a model solute. Experiments were carried out by varying feed flow rate, feed concentration and feed pressure and recording the readings of permeate concentration, retentate flow rate, retentate concentration and retentate pressure. A total of 73 experimental readings were recorded. The membrane transport parameters Aw (solvent transport coefficient) and Bs (solute transport coefficient) and the feed channel friction parameter b were estimated by a graphical technique developed in this work. The mass transfer coefficient k, estimated using the experimental data, was found to be strongly influenced by solvent flux and solute concentration apart from the fluid velocity. Taking the effects of solvent flux, solute concentration and fluid velocity, a new mass transfer correlation for Sherwood number is proposed in this work for the estimation of mass transfer coefficient. Comparison of model predictions with experimental observations demonstrated that the model was capable of predicting permeate concentration within 10% error, retentate rate flow within 4% error and rejection coefficient within 5% error. © 2011 Elsevier B.V.
Residence Time Distribution Studies in a Modified Rotating Packed Disc Contactor: Mathematical Modeling and Validation
(De Gruyter Open Ltd, 2020) Kalnake, R.P.; Murthy, D.V.R.; Achar, A.; Raval, K.
A modified rotating packed disc contactor (RPDC) with the maximum working volume of 65 liter is designed for biological waste water treatment. A hollow disc with radial vanes mounted on the disc was a modified design of this contactor. Stimulus-response experiments were conducted in the contactor to understand liquid mixing behavior under different operating conditions. The recycle stream was also used in the operation of the contactor. Experiments were conducted for different number of discs, rotational speeds and recycle ratios. The disc design and recycle ratio had marked influence on the mixing behavior. An increase in disc rotation and recycle ratio produced a well-mixed flow behavior. Moreover, the surface area available in the RPDC was about 4 times more than the surface area available in a standard rotating biological contactor (RBC) operating at similar conditions. A mathematical model was developed for the flow behavior under recycle and a good agreement was found between the model and experimental results. © 2020 Walter de Gruyter GmbH, Berlin/Boston 2020.
Separation of dimethyl phenol using a spiral-wound RO membrane - Experimental and parameter estimation studies
(2009) Srinivasan, G.; Sundaramoorthy, S.; Murthy, D.V.R.
Reverse osmosis (RO) is increasingly used as a separation technique in chemical and environmental engineering for the removal of organics and organic pollutants present in waste water. Treatment of organics by RO is dependent on many factors and hence developing a viable RO system involves extensive pilot-plant studies. The removal of an organic compound, namely dimethyl phenol, using a polyamide membrane was investigated in this study. Experiments were conducted on a laboratory-scale spiral-wound RO module. The permeate concentrations and rejection coefficient values were measured for various transmembrane pressures and feed concentrations. A maximum rejection of 97% was observed. A mathematical model was developed for the RO module assuming a solution-diffusion mechanism for solute and solvent transport through the membrane and considering the concentration and pressure to be uniform on both permeate and retentate sides. The model has four parameters. A graphical method for estimating the model parameters was proposed. The model and the estimated parameter values were validated with the experimental data. The model was able to predict the permeate concentration within an error of 19% and rejection within 2% error. © 2009.
Slow release studies on commercial urea briquettes in loam and Silty clay soils of Karnataka, India
(2011) Bhat, M.; Murthy, D.V.R.; Saidutta, M.B.
In order to curtail losses of urea in wet agricultural soils, one of the cost effective method adopted is application of urea in large sized form such as briquettes. Commercially available pillow shaped uncoated urea briquettes and the briquettes modified by encapsulating them with kokum wax and paraffin wax coatings were subjected to release in two different soils of Karnataka viz. loam soil and silty clay soil. Results indicate that clay rich soil retarded dissolution of uncoated briquettes. Both kokum wax and paraffin wax coatings acted as good barriers for release of urea. These coatings were susceptible to rupture and release from the exposed areas. Kokum wax outperformed paraffin wax in all the soils. However, kokum wax coating was less stable in silty clay soil and the coating displayed higher shelf life in loam soil. Temperature accelerated the dissolution of both the uncoated as well as kokum coated briquettes in wet soil. © 2011 CAFET-INNOVA technical society. All right reserved.
Stimulus response experiments are conducted in four different rectangular columns having two and three spout cells. A pink-coloured polymer material is used as bed material with ambient air as the spouting fluid. A pulse input of dark blue colour polymer material is used as the stimulus, when the column is operating under steady flow conditions, and the response measured. A mathematical model 'plug flow-mixed flow in series' is used to fit the experimental data and the model parameters are evaluated.
(Can Soc for Chem Eng, Mixing behaviour of solids in multiple spouted beds) Saidutta, M.B.; Murthy, D.V.R.
2000
Studies have been carried out in multiple spouted beds having 2, 3 and 4 spout cells; different fluid inlet orifices and different solids have been used with air and water as spouting fluids. The minimum spouting velocities are measured for different bed depths. The experimental data for particle Reynolds number at minimum spouting have been correlated and the square root mean deviation between the calculated and experimental values is found to be 8.75 %. Copyright © 1994 Canadian Society for Chemical Engineering
(Minimum spouting velocity in multiple spouted beds) Murthy, D.V.R.; Singh, P.N.
1994
Validation of an analytical model for spiral wound reverse osmosis membrane module using experimental data on the removal of dimethylphenol
(2011) Srinivasan, G.; Sundaramoorthy, S.; Murthy, D.V.R.
A new analytical model for spiral wound RO module has been recently proposed by Sundaramoorthy et al. [1] and the same has been validated [2] with experimental data obtained on a laboratory scale RO unit used for the removal of chlorophenol. In this paper, the need to check the validity of this model with solutes other than chlorophenol is addressed by conducting suitable experiments with dimethylphenol as solute and validating this experimental data with the model. The four model parameters namely solvent transport coefficient Aw, solute transport coefficient Bs, feed channel friction parameter b and the mass transfer coefficient k were estimated. The results show that the mass transfer coefficient is influenced not only by fluid velocity but also by the solvent flux and solute concentration. A new correlation for mass transfer coefficient k, proposed by Sundaramoorthy et al. [2] for experimental data taken with chlorophenol as solute is also shown to be consistent with the experimental readings recorded in this study taking dimethylphenol as solute. Comparison of model predictions with the experimental observations demonstrated the capability of the model in predicting permeate concentration within 12% error, retentate flow within 5% error and rejection coefficient within 2% error. © 2011 Elsevier B.V.