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High permeability of tire shreds/chips makes them suitable for many landfill applications but few concerns were raised by landfill designers/operators mainly related with excessive compressibility ...

Relative drainage performance of gravel and tire chips used alone and in different combinations were evaluated through the results of drainage plate settlement and leachate conductivity testing under incremental overburden pressure levels. Experiments were performed to assess the appropriate tire chips size (in particular aspect ratio) for their large-scale uses as leachate drainage layer material. Potential of clogging for the optimized size tire chips and their mixes with gravel of transmitting relatively “high-strength” leachate were also examined. Results showed that “small” size tire chips of aspect ratio 1 (average length 22–25 mm) are suitable for relatively lower drainage plate settlement and higher leachate conductivity values. Additionally, combinations with ds/dg = 0·25 and 0·50 (by thickness) when scrap tire chips and gravel were used as separate layers gave “lesser clogging and free drainage” up to higher vertical overburden pressure levels. Alternatively, 25% of tire chips (by weight) mixed ...

Studies on axial dispersion are vital in assessing the performance of a reactor. The various factors that affect the axial dispersion in a packed bed reactor include fluid flow rate, physical properties of the fluids and bed configurations. In the present study, the effect of surface tension and viscosity of the fluid on axial dispersion in the packed bed reactor has been studied. Tap water, sodium lauryl sulphate in tap water and polyethylene glycol in tap water were used as liquid phases to give variations in surface tension and viscosity of the fluids. Axial dispersion has been measured by residence time distribution–response curves using pulse tracer technique. The one-dimensional axial dispersion model was used to analyse the axial dispersion in terms of Bodenstein number. The Bo L number was observed to increase with decrease in surface tension of the fluid, whereas it increased with the increase in viscosity of the fluid. Based on the experimental data of low surface tension and viscous fl...

The present study has been carried out to assess the nutrient removal potential of two different algal species in immobilized alginate beads for nutrient removal from wastewater. Chlorella minutissima and wild algae isolated from a local dairy waste treatment plant were used in the study. The percentage removal of nutrients (ammonia-N, phosphate and nitrate-N) by algal alginate beads at different time intervals in an aerated photobioreactor has been investigated. Percentage removal of ammonia-N (94% in 48 h) was higher for C. minutissima while dairy waste isolated algae species showed significant removal efficiency for phosphate (100% in 48 h) and nitrate-N (62.5% in 48 h). The study showed that immobilized Chlorella minutissima and isolated wild algae beads were significantly efficient in removing ammonia-N and phosphate from local sewage wastewater.

Pressure drop is an important parameter in the process design and performance of trickle bed reactors as it affects the energy requirements and hence the operating cost and sizing of the reactor. Various hydrodynamic factors that influence the two-phase pressure drop of a trickle bed reactor when Newtonian liquid phases are involved include gas flow rate, liquid flow rate, surface tension of the liquid phase, viscosity of the liquid phase, and bed characteristics such as porosity and sphericity of the packing material. For viscoinelastic fluid flow consistency index K and flow behavior index n are observed to affect the pressure drop significantly, whereas, for viscoelastic fluids, fluid elasticity leads to higher pressure drop. In the present study the effects of various parameters (involving bed characteristics and liquid-phase properties ranging from simple water-like Newtonian fluids to complex viscoelastic non-Newtonian fluids) on two-phase pressure drop are investigated. A wide range of correlations...

Axial dispersion has been measured in a laboratory-scale model trickle bed reactor at different liquid and gas flow rates under co-current down-flow condition. Air was used as gas phase and water or aqueous polyethylene glycol solution was used as liquid phase, covering the Reynolds number range of 0–164 for gas phase and 4–86 for liquid phase. Liquid phase residence time distribution was measured using a 1 M KCl pulse tracer. The axial dispersion model was used to simulate the observed RTD, and liquid phase PeL and BoL were estimated as model parameters. Based on the results, it was observed that under low interaction flow regime (trickle flow), liquid phase Bodenstein number, BoL, increased gradually with liquid phase Reynolds number, ReL, and was found to be nearly independent of gas phase Reynolds number, ReG. Near the flow transition point, BoL or PeL decreased, and in the high interaction regime it showed an oscillatory response. In the trickle flow regime .

Hydrodynamic behavior of a trickle bed reactor is dependent on the flow regime that arises when gas and liquid flow concurrently downward in the reactor. Empirical or semi-analytical models available in the literature do not predict to satisfaction the transition between the trickle and pulse flow regimes in cocurrent down flow in a TBR. In the present study, flow transition between trickle flow (low-interaction) and pulse flow (high-interaction) regimes was experimentally observed for different non-foaming Newtonian and non-Newtonian liquid phases under concurrent down flow conditions with air in a packed bed using different bed configurations. The effect of bed geometry along with fluid phase properties has been considered to modify the flow map coordinates, so as to collapse the data corresponding to different bed configurations and Newtonian liquid-phase properties onto a single curve (within±20%). An empirical correlation for the prediction of Newtonian liquid-phase mass velocity at the tran...