Biosurfactants are surface active substances which reduce interfacial tension and are produced or excreted at the microbial cell surface. We evaluated the biosurfactant production by Aspergillus fumigatus and Phialemonium sp. in solid state processes using fixed-bed column reactors. We evaluated two media, rice husks alone (simple support) and rice husks plus defatted rice bran (complex support...

Dear Sirs, In a recent series co-workers (see e.g. of papers by Morbidelli and Varma and Morbidelli and Varma 1986a; Morbidelli et al., 1986h Lee and Varma, 1987, 1988; Bauman and Varma 1990), the multiplicity behaviour of a fixed bed reactor is discussed. The basis for this analysis was given by Morbidelli and Varma (1986a) and Morbid& et al. (1986b), where the authors devote many columns to m...

Heat and mass transfer problem in a fixed-bed tubular reactor is one of the major concerns in the chemical engineering. The two dimensional axial plug flow model was used for a water gas shift reactor to compare heat conduction or mass diffusion with convective effect. In the case of fast fluid flow in highly permeable catalyst-bed, convective heat transfer was dominant compared to heat conduct...

application of granular activated carbon (gac) in adsorption process has been studied for the advanced treatment of municipal and industrial wastewater. because of entering poisonous compounds such as furfural, phenol and sulfides into the oily wastewater of tehran refinery, biological aeration basins of wastewater treatment unit may not have the desired performance of cod reduction. in this st...

Inefficient use of raw materials in most catalytic processes can be attributed mainly to the deactivation of the catalyst in chemical reactors. In order to achieve efficient use of raw materials, this paper addresses mitigation of deactivation through optimization of inlet temperature-time trajectories. The optimization of temperature profiles in reactors is one of the key problems in the synth...

A one-dimensional, unsteady mathematical model is presented of fixed-bed countercurrent wood gasifiers, which couples heat and mass transport with wood drying and devolatilization, char gasification, and combustion of both char and gas-phase species. The model is used to simulate the structure of the reaction fronts and the gasification behavior of a laboratory-scale plant as the reactor throug...

This work presents a general mathematical model of a fixed bed gasifier, where both the transport resistances and the chemical kinetics are important at the reactor and the particle scale. Pyrolysis and gasification of the solid fuel (coal, plastics, biomasses or wastes) is only the first step of the whole process. Successive gas phase reactions of the released species are described with a deta...

Natural Organic Matter (NOM) normally exists in raw surface water as a complex mixture of organic compounds, mainly humic acids and fulvic acids. In water treatment plants, free chlorine reacts with NOM and forms a wide range of substances known as Disinfection Byproducts (DBPs). Granular Activated Carbon (GAC) adsorption is one of the best available technologies employed for the removal of NOM...

A fixed bed reactor design program is developed by the use of Java JDK1.7 algorithm language with Eclipse program as the platform. The program selects five common fix bed reactor process flows to calculate the main structure parameters of the reactor. With the good interface, the program can output the corresponding results after inputting the kinetics and thermodynamics parameters of the react...

Miscanthus x giganteus was pyrolysed, in a fixed bed reactor in a constant flow of dinitrogen gas, at a rate of 13°C/min from ambient to 550°C, then held for 25 min at this temperature. The pressures employed ranged from atmospheric to 26 bar. The major compounds identified in the bio-oil were water, phenol, and phenol derivatives. The water contents impact on the usefulness of the bio-oil as a...