scholarly journals Experimental Investigation of Biomass Attachment to Wastewater Reactors

2020 ◽  
Author(s):  
Renato Benintendi
Keyword(s):  
Mass Transfer ◽  
Enzymatic Catalysis ◽  
Wastewater Management ◽  
Attached Mass ◽  
Research Activity ◽  
Systematic Analysis ◽  
Steady State Operation ◽  
Start Up ◽  
Reaction Theory ◽  
Experimental Findings

Attached mass bioreactors have extensively been adopted in the last decades when specific needs have suggested this choice. Benefits and advantages of this multi-faceted technology in wastewater treatment processing are well known, along with the kinetic and mass transfer aspects regarding their operation, essentially belonging to the mass transfer with chemical reaction theory applied to enzymatic catalysis, referred to as Languimur-Hinshelwood kinetics, notably Monod/Michaelis Menten equations. On the other hand, a consolidated literature has dealt with many aspects of the development of strain colonies forming a biofilm. However, a few works have been devoted to the systematic analysis of its physiology, within the framework of the wastewater management of complex substrates and high-loads effluents. This article presents the experimental findings of a research activity covering the junction area between microbiology and bioreactor engineering, against a multifaceted set of operating parameters directly affecting health and stability of the attached biomass. In this respect, important results have been obtained, providing guidance on the attached mass reactor start-up, steady- state operation, impact of xenobiotic substrates, role of nutrients, filaments and foam formation, as well as qualitative aspects of the post-treatment effluent.

scholarly journals Open-cell foams as catalysts support: A systematic analysis of the mass transfer limitations

2020 ◽  
Vol 393 ◽  
pp. 124656 ◽  
Author(s):  
A. Aguirre ◽  
V. Chandra ◽  
E.A.J.F. Peters ◽  
J.A.M. Kuipers ◽  
M.F. Neira D'Angelo
Keyword(s):  
Mass Transfer ◽  
Systematic Analysis ◽  
Open Cell ◽  
Open Cell Foams

Water–mineral interaction in hygromechanics of clays exposed to environmental loads: a mixture-theory approach

1992 ◽  
Vol 29 (6) ◽  
pp. 1071-1086 ◽  
Author(s):  
Tomasz A. Hueckel
Keyword(s):  
Mass Transfer ◽  
Mixture Theory ◽  
Adsorbed Water ◽  
Theory Approach ◽  
Environmental Loads ◽  
Fluid Fraction ◽  
Effects Of Temperature ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Mineral Interaction

Water–mineral interaction in narrow interstices (<30 Å (1 Å = 0.1 nm)) in dense, saturated clays is discussed in view of recent experimental findings and molecular dynamics simulations. Consequences to the macroscopic behavior are considered. A mixture theory for two interacting constituents is developed. Effects of temperature and chemicals are discussed. A postulate of mass transfer of adsorbed water from solid to fluid fraction caused by thermal or chemical load is then discussed. Theory of plasticity of clays affected by heat or chemicals is developed to deal with the effects of thermal and chemical consolidation. Key words : hydraulic conductivity, effective stress, environmental loads, thermo-chemo-plasticity.

Solution of the Classic Thermal Regenerator Problem

1994 ◽  
Vol 208 (3) ◽  
pp. 187-197 ◽  
Author(s):  
A J Organ
Keyword(s):  
Thermal Capacity ◽  
Recovery Ratio ◽  
Cotton Wool ◽  
Gas Temperature ◽  
Stirling Cycle ◽  
Steady State Operation ◽  
Start Up ◽  
Temperature Swing ◽  
Temperature Recovery ◽  
Conventional Picture

An exact, general and algebraically simple solution is obtained to the classic model of the thermal regenerator—general in the sense of covering flushing ratios, A, of any magnitude, including the small values of interest in the context of Stirling cycle machines, and of depicting start-up and cyclic steady state operation. Specimen solutions turn the conventional picture of regenerator performance on its head: for a flushing ratio equal to or less than unity, for example, zero heat-transfer coefficient (NTU = 0) leads to a temperature recovery ratio of 100 per cent! At a thermal capacity ratio, NTCR, above a certain, minimal, value, the wall temperature distribution sits invariant between the extremes of gas temperature swing, and increased NTCR has no effect on temperature recovery ratio. The findings are sufficient to explain reports of unexpectedly good performance of Stirling machines with regenerators of cotton wool or glass fibre.

A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment

2016 ◽  
Vol 74 (5) ◽  
pp. 1088-1095 ◽  
Author(s):  
Yingwen Chen ◽  
Jinlong Zhao ◽  
Kai Li ◽  
Shitao Xie
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Fluidized Bed ◽  
Terephthalic Acid ◽  
Oxygen Demand ◽  
Biofilm Reactor ◽  
Stable Chemical ◽  
Start Up ◽  
Operation Stability ◽  
Purified Terephthalic Acid

In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5–10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m−3.d−1. The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability.

scholarly journals Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Paul Aigner ◽  
Christian Paulik ◽  
Apostolos Krallis ◽  
Vasileios Kanellopoulos
Keyword(s):  
Mass Transfer ◽  
Catalyst Activity ◽  
Plug Flow ◽  
Mass Transfer Process ◽  
Catalyst System ◽  
Transfer Model ◽  
Catalyst Activation ◽  
Before And After ◽  
Natta Catalyst ◽  
Experimental Findings

In industrial-scale catalytic olefin copolymerization processes, catalyst and cocatalyst precontacting before being introduced in the polymerization reactor is of profound significance in terms of catalyst kinetics and morphology control. The precontacting process takes place under either well-mixing (e.g., static mixers) or plug-flow (e.g., pipes) conditions. The scope of this work is to study the influence of mixing on catalyst/cocatalyst precontacting for a heterogeneous Ziegler-Natta catalyst system under different polymerization conditions. Slurry ethylene homopolymerization and ethylene copolymerization experiments with 1-butene are performed in a 0.5 L reactor. In addition, the effect of several key parameters (e.g., precontacting time, and ethylene/hydrogen concentration) on catalyst activity is analyzed. Moreover, a comprehensive mass transfer model is employed to provide insight on the mass transfer process and support the experimental findings. The model is capable of assessing the external and internal mass transfer limitations during catalyst/cocatalyst precontacting process. It is shown that catalyst/cocatalyst precontacting is very important for the catalyst activation as well as for the overall catalyst kinetic behavior. The study reveals that there is an optimum precontacting time before and after which the catalyst activity decreases, while this optimum time depends on the precontacting mixing conditions.

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