The removal of lead and zinc from a binary solution by fixed bed depths (40, 80 and 120 mm) of a natural zeolite was examined at a flow rate of 1 mL/min. The results obtained were fitted to the Bed Depth Service Time (BDST) model and the parameters of the model (q and k) were used to design a column system for flow rates of 2 and 3 mL/min at a bed depth of 80 mm. The experimental results were in excellent agreement with those predicted and experimental breakthrough curves for the binary systems were obtained. This approach facilitates the design of effective binary column processes without additional experimentation. Two major design parameters, the Empty Bed Contact Time (EBCT) and the zeolite usage rate, were calculated. The highest EBCT value of 13.56 min represents the optimal conditions for the binary (Pb+Zn) solution.

The goal of the combustion research is to achieve optimum combustion mode. Reaction Front velocity is one of the most important parameter that is studied in this field. Most biomass consumed at the present time is burned in fixed or moving beds. Fixed-bed combustion systems are characterized by the slow combustion of large particles subjected to an oxidizing ambient. In this paper a model for propagation of a reaction front of wood particles in a fixed Bed is presented. Once the bed is ignited, an apparent flame zone is formed at the bed's top surface and the flame front moves downwards into the bed of fuel at a speed depending on fuel type and operating parameters. Effect of different parameters such as air flow rate through the bed, primary air temperature, moisture content, particle size and number density of fuel particles on the reaction front velocity has been studied. In order to compare the results of this model with the associated experimental data three species of wood fuels are studied and the agreement is found to be satisfactory.