A STUDY ON DENITRIFICATION IN A FLUIDIZED BED BIOREACTOR

The work involves experimental investigation on biological denitrification in a fluidized bed reactor under anaerobic conditions using the microorganism Pseudomonas Stutzeri and plastic beads as fluidizing medium. The influence of various parameters like pH, initial nitrate concentration, Carbon/Nitrogen ratio, hydraulic retention time on nitrate-nitrogen removal rate from synthetic effluent prepared at the laboratory were studied in detail. The optimum operating conditions of pH, initial nitrate concentration, Carbon/Nitrogen ratio and flow rate obtained are 7.0–7.5, 15 mg/l, 1.5–2.0 and 4.41 x 10-5 m3/s respectively

Ultrafine aluminium: Quench collection of agglomerates

Combustion of aluminized solid propellants exhibits phenomena associated with accumulation, agglomeration, ignition, and combustion of ultra-fine aluminium particles. In this study, agglomeration phenomenon of ultra-fine aluminium in solid propellant combustion is investigated using quench collection experimental technique over the pressure ranges from 2MPa to 8MPa. The ultra-fine aluminium powder synthesized by Radio Frequency Induction Plasma technique having harmonic mean size of 438nm is used for agglomeration study. The quenching distance is varied from 5mm to 71mm from the propellant burning surface to estimate the effect on agglomerate size. The morphology and chemical compositions of the collected products were then studied by using scanning electron microscopy coupled with energy dispersive (SEM-EDS) method. Under the explored experimental conditions, the results confirm that ultra-fine aluminium propellant show aggregation/agglomeration with the size ranging from 11 – 21 μm in combustion products. Smaller diameter condensed phase products will likely decrease two-phase flow loss and reduce slag accumulation

Application of artificial neural networks for the prediction of aluminium agglomeration processes

Aluminium is universal and vital constituent in composite propellants and typically used to improve performance. Aluminum agglomeration takes place on the burning surface of aluminized propellants, which leads to reduced combustion efficiency and 2P flow losses. To understand the processes and behaviour of aluminum agglomeration, particles size distribution of composite propellants were studied using a quench particle collection technique, at 2 to 8 MPa and varying quench distances from 5mm to 71mm. To predict the agglomerate diameter of metallized/ultra-fine aluminium of composite propellants, a new artificial neural network (ANN) model was derived. Five Layered Feed Forward Back Propagation Neural Network was developed with sigmoid as a transfer function by varying feed variables in input layer such as Quench distance (QD) and pressure (P). The ANN design was trained victimization stopping criterion as one thousand iterations. Five ANN models dealing with the combustion of AP/Al/HTPB and one ANN model of AP/UFAl/HTPB composite propellants were presented. The validated ANN models will be able to predict unexplored regimes wherein experimental data are not available. From the present work it was ascertained that, for agglomeration produced by quench collection technique, the ANN is one of a substitute method to predict the agglomerate diameter and results can be evaluated rather than experimented, with reduced time and cost. The resulting agglomerates sizes from ANN model, matches with the experimental results. The percentage error is less than 3.0% of the label propellants used in this work

Experimental studies and thin layer modeling of pearl millet using continuous multistage fluidized bed dryer staged externally

The fluidized bed dryers are one of the prominent moisture removal dryers in industries. Various studies have been conducted by previous researchers to improve the product quality and efficiency of dryers with various modified designs. In the present study, experiments were carried out using multistage fluidized bed dryer staged externally, changing operating conditions such as wall temperatures (313–328 K), velocity of air (1.01–1.3 m/s), downcomer height (50–70 mm) and solid flow rate (5–10 kg/h). Drying characteristics of solids in dryers at various stages was reported and comparison was made with single and multiple stage fluidized bed dryer. Experimental data were validated with various models and reported model parameters of multistage fluidized bed dryer at various conditions and stage-wise were reported at minimum RMSE error. Moisture diffusivity and activation energies were estimated at various conditions and reported. Keywords: Multistage fluidized bed dryer, Drying characteristics, Effective diffusivity, Activation energ

Residence time distribution of solids in a fluidised bed

100-106The present work involves an experimental investigation on residence time distribution of solids in a continuous fluidised bed for uniform size and for binary solid mixture at different dilutions. The column was tested for improvement in performance with increase in dilution. The effect of gas flow rate, solids flow rate and dilution on the first, second and third moments and on F-curves have been determined. Fractional tank extension model fits the experimental data. High values of N as dilution increases, indicates reduced solids mixing, thus reducing spread of residence times, giving rise to more uniform quality of product. The work finds importance in that similar improved performance of the column using internals inside the bed can be obtained by using a mixture of solids rather than uniform size.

Extraction of ligninolytic enzymes from novel Klebsiella pneumoniae strains and its application in wastewater treatment

Abstract The presence of lignin and its derivatives in pulp effluent increases the pollution load on the environment. With an aim of better degradation and decolourization of wastewater, this study proposes the utilization of different ligninolytic enzymes from novel bacterial strains. Four novel bacterial strains of Klebsiella pneumoniae (K. pneumoniae strains NITW715076, NITW715076_1, NITW715076_2 and NITW715076_3) were isolated and identified. The ligninolytic enzymes were characterized by plate assay method. For the optimization of various process parameters of effluent sample, different approaches were used like one factor at a time and statistical optimization through response surface methodology (RSM). Further to validate the above data, enzyme activity, total phenolic concentration, GC–MS analysis and seed germination test were also performed. The ligninolytic enzymes produced were characterized as laccase and Manganese peroxidase (MnP). In lignin degradation and decolourization studies, consortia 1 (K. pneumoniae NITW715076_2 + K. pneumoniae NITW715076_1) (82.31%) was found more effective when compared to axenic culture (K. pneumoniae NITW715076_2) (74.1%). In RSM studies, Laccase and MnP activities were increased by 20% and 18%, respectively, as compared to one factor at a time optimization method. In addition, the enzyme activity for laccase and MnP after prediction by RSM was found 53338 IU/L and 147900 IU/L, respectively. The R 2 values for both the enzymes were found to be significant. Further, GC–MS analysis also showed the degradation of different organic pollutants in effluent. Lastly, the seed germination test using consortia 1 corroborated the evidence of detoxification of industrial effluent. Effluent treated by consortia 1 showed better results in degradation and decolourization of lignin and their derivatives. Therefore, consortia 1 can be used for various industrial purposes like fruit juice clarification, diagnostic purposes and enhanced bioethanol production

Development of a model for drying of solids in a continuous fluidized bed dryer

477-482A mathematical model to describe the drying characteristics of solids in a continuous fluidized bed dryer has been developed. The RTD model proposed by Pydi Setty et al.1 is used to obtain the required drying model. Experimental data in a continuous fluidized bed dryer are satisfactorily matched with the model developed. Using the model, one can predict the average moisture content relative to the initial moisture content in a continuous fluidized bed dryer for the given operating conditions