scholarly journals On the asymptotic stability of advection-diffusion equations of mass transport in a bubble column bioreactor

2021 ◽  
Vol 2090 (1) ◽  
pp. 012035
Author(s):  
Paola Lecca ◽  
Angela Re
Keyword(s):  
Acetic Acid ◽  
Control System ◽  
Asymptotic Stability ◽  
Bubble Column ◽  
Bubble Column Reactor ◽  
Dissolved Gas ◽  
Advection Diffusion Equation ◽  
Bubble Column Bioreactor ◽  
Advection Diffusion ◽  
By Products

Abstract This study presents an asymptotic stability analysis of a model of a bioreactor converting carbon monoxide (CO) gas into ethanol through a C. autoethanogenum biocatalyst. The configuration is a bubble column reactor with co-current gas-liquid flows where gas feed is introduced by a gas distributor placed at the bottom of the column. A pure culture of C. autoethanogenum is subsequently injected at the bottom of the column; therein, cells are dispersed in the liquid and consume the dissolved gas and release by-products such as ethanol and acetic acid. Cellular growth and byproduct secretion are affected by spatially varying dissolved gas concentrations due to advection-diffusion mass transports which are induced by the effect of the injection pressure and gravitational force. The model accounts for four species representing the biomass, the CO substrate in the liquid phase, and two by-products - ethanol and acetic acid. Substrate dynamics is described by an advection-diffusion equation. We investigate the asymptotic stability of the biomass dynamics that is a requirement for the system’s controllability, i.e. for the possibility to steer a dynamical system from an arbitrary initial state to an arbitrary final state using a set of controls. The concept of stability of the controls is extremely relevant to controllability since almost every workable control system is designed to be stable. If a control system is not stable, it is usually of no use in practice in industrial processes. In the case of a bioreactor, the control is the biomass and controllability is the possibility of modulating through this control the ethanol production. We present a test for asymptotic stability, based on the analysis of the properties of the dynamic function defining its role as storage function.

scholarly journals Vinegar production from Theobroma grandiflorum SCHUM (cupuassu)

2021 ◽  
Vol 8 (4) ◽  
pp. 257-266
Author(s):  
Ana Paula Guedes Pinheiro ◽  
◽  
Augusto Bücker ◽  
Ana Cláudia Cortez ◽  
João Vicente Braga de Souza ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Bubble Column ◽  
High Surface ◽  
Univariate Analysis ◽  
Bubble Column Reactor ◽  
Close Relative ◽  
Tropical Fruit ◽  
Theobroma Grandiflorum ◽  
Acid Acid ◽  
The Rich

<abstract> <p>The tropical fruit cupuassu comes from <italic>Theobroma grandiflorum</italic> (SCHUM), a close relative of cocoa. Cupuassu has a rich yet delicate flavour profile with notes of chocolate, pineapple, passion fruit and other fruits. Here, we produced a cupuassu-fruit wine using a Saccharomyces cerevisiae inoculum (and univariate analysis to determine conditions for optimum ethanol production) and then fermented this wine to produce a delicate and unique cupuassu vinegar using acid-acid bacteria. The cupuassu wine was produced by fermentation of juice chaptalized with sucrose, with a final ethanol concentration of 10% (v/v). Acetic-acid fermentations were carried out in both a bubble-column reactor and a mechanically non-aerated reactor (high-surface reactor), producing final concentrations of 4.5 and 3.3% (w/v) acetic acid, respectively. The ethanol- and acetic-acid yields obtained were comparable to those of other fruit wines and fruit vinegars. The cupuassu vinegar retained the rich flavor profile of the cupuassu. We believe that the production of flavorsome products from local plants can have benefits for conservation by promoting ecologically sustainable agriculture and may contribute to cultural identity of Amazon people.</p> </abstract>

scholarly journals Degradación del 2,5-DCP en agua destilada y en agua residual por los procesos de oxidación avanzada con ozono y ozono-UV combinados con un tratamiento biológico

2016 ◽  
Author(s):  
◽  
Jacqueline Catherine Alexander
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Bubble Column ◽  
Bubble Column Reactor ◽  
High Concentration ◽  
Ozone Dose ◽  
Pore Glass ◽  
Pharmaceutical Industries ◽  
Uv Lamp ◽  
By Products

In recent years, there have been increases in contamination of water supplies, due to the continuous discharge of wastewater from chemical and pharmaceutical industries, without them being properly treated to remove the refractory organic compound they may contain. These contaminants endanger the quality of surface and groundwater, the ecosystems, and the health of the world´s population. In view of these problems, the present work examined the effectiveness of combining ozone and ozone-UV processes with a biological treatment to increase biodegradability and reduce toxicity levels of the chlorophenolic compound, 2,5-dichlorophenol (2,5-DCP) and its oxidative intermediates. A comparative study was carried out in a glass bubble column reactor equipped with a fine-pore glass diffuser with a volumetric mass transfer kLa of 1.58 min-1. Each experiment was done using a 1.5 L volume of 2,5-DCP (3.07 mM) aqueous solution of distilled water and municipal wastewater, at pH 7 with an applied ozone dose of 22 mg min-1 and an oxygen-ozone flow rate of 0.7 L min-1. Additionally, a low mercury UV lamp with wavelength of 254 nm was used during ozone-UV treatments. The results obtained, showed that 2,5-DCP was completed degraded with an ozone dose of approximately 1.2 g h-1 in both solutions, treated with ozone and ozone-UV processes. The best results were obtained with the ozone-UV processes after 60 min of oxidation, showing that the addition of photolysis treatment (UV lamp intensity = 4 mW cm-2) to ozone, accelerated COD removal (75%), mineralization (53%) and biodegradability (BOD5/COD) of 2,5-DCP from 0.2 to 0.85 in the wastewater. The toxicity of 2,5-DCP and its oxidation by-products were monitored at different time intervals using activated sludge respiration inhibition tests. The test analyses showed that ozone and ozone-UV treatments were effective in reducing the toxicity of 2,5-DCP and its by-products, which were less toxic to the microorganisms in activated sludge (IC25 = 135 mg/L), than the untreated 2,5-DCP solutions (EC50= 50 mg/L). The results achieved in this work, showed that the presence of organic and inorganic matters in the wastewater, had a positive effect on the oxidation of 2,5-DCP, which support the potential use of ozone and ozone-UV processes for the treatment of effluent with high concentration of chlorophenols.

scholarly journals Brine Recycling from Industrial Textile Wastewater Treated by Ozone. By-Products Accumulation. Part 2: Scaling-Up

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 233 ◽  
Author(s):  
Lucyna Bilińska ◽  
Kazimierz Blus ◽  
Marta Gmurek ◽  
Renata Żyłła ◽  
Stanisław Ledakowicz
Keyword(s):  
Textile Industry ◽  
Bubble Column ◽  
Reaction Medium ◽  
Textile Wastewater ◽  
Scaling Up ◽  
Bubble Column Reactor ◽  
Purification Method ◽  
Alkaline Reaction ◽  
Standard Values ◽  
By Products

Extremely high volumes of salty wastewater are produced by textile manufacturers daily. Therefore, brine recycling from the wastewater should be regarded as a crucial issue within the textile industry. Ozonation was used in this two-part study as a purification method for industrial textile wastewater polluted by low-molecular-weight salts (LMWS). Part 1 revealed the accumulation of ozonation by-products in a multi-recycling system. The objective of Part 2 was the scaling-up of the process and the investigation of the occurrence of by-products. It was found that ozonation works well in an alkaline reaction medium, which was characteristic of the wastewater from a dye house; an almost complete color removal was achieved within 30 min of treatment. The brine that was produced from the wastewater treated by ozonation in a 20 L bubble column reactor was recycled successfully. Dyeing of cotton with five types of reactive dyes in various shades resulted in very good values of DECMC, which is the normative color matching parameter, and were between 0.15 and 1.2. The color fastness obtained for upcycled fabrics were satisfactory, and not worse than standard values. Although accumulation of the side products was detected in Part 1, the fabric discharges produced in the scaled-up process were free from carcinogenic amines and heavy metals. The study indicated that ozonation can be applied in the industry as a method for textile wastewater recycling.

scholarly journals Concentrating Model Solutions and Fruit Juices Using CO2 Hydrate Technology and Its Quantitative Effect on Phenols, Carotenoids, Vitamin C and Betanin

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 626
Author(s):  
Alexander Rudolph ◽  
Amna El-Mohamad ◽  
Christopher McHardy ◽  
Cornelia Rauh
Keyword(s):  
Vitamin C ◽  
Food Production ◽  
Bubble Column ◽  
Hydrate Formation ◽  
Fruit Juices ◽  
Bubble Column Reactor ◽  
High Concentration ◽  
Model Solutions ◽  
Concentration Potential ◽  
Concentration Methods

Fruits have an important economic impact in the context of plant-based food production. The consumption of fruit juices, mostly produced from concentrates, is particularly noteworthy. Conventional concentration methods do not always enable a sustainable and gentle concentration. The innovative gas hydrate technology addresses this point with its energy-saving, gentle character, and high concentration potential. In this study, the concentration of fruit juices and model solutions using CO2 hydrate technology was investigated. To find a suitable operating point for hydrate formation in the used bubble column, the hydrate formation in a water–sucrose model solution was evaluated at different pressure and temperature combinations (1, 3, 5 °C and 32.5, 37.5, 40 bar). The degrees of concentration indicate that the bubble column reactor operates best at 37.5 bar and 3 °C. To investigate the gentle processing character of the hydrate technology, its quantitative effects on vitamin C, betanin, polyphenols, and carotenoids were analyzed in the produced concentrates and hydrates via HPLC and UV/VIS spectrophotometry. The results for fruit juices and model solutions imply that all examined substances are accumulated in the concentrate, while only small amounts remain in the hydrate. These amounts can be related to an inefficient separation process.

scholarly journals Global heat balance and heat uptake in potential temperature coordinates

2021 ◽  
Author(s):  
Antoine Hochet ◽  
Rémi Tailleux ◽  
Till Kuhlbrodt ◽  
David Ferreira
Keyword(s):  
Global Warming ◽  
Water Mass ◽  
Potential Temperature ◽  
Effective Diffusion ◽  
Mitigation Strategies ◽  
Ocean Heat Uptake ◽  
Cold Temperatures ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Heat Uptake

AbstractThe representation of ocean heat uptake in Simple Climate Models used for policy advice on climate change mitigation strategies is often based on variants of the one-dimensional Vertical Advection/Diffusion equation (VAD) for some averaged form of potential temperature. In such models, the effective advection and turbulent diffusion are usually tuned to emulate the behaviour of a given target climate model. However, because the statistical nature of such a “behavioural” calibration usually obscures the exact dependence of the effective diffusion and advection on the actual physical processes responsible for ocean heat uptake, it is difficult to understand its limitations and how to go about improving VADs. This paper proposes a physical calibration of the VAD that aims to provide explicit traceability of effective diffusion and advection to the processes responsible for ocean heat uptake. This construction relies on the coarse-graining of the full three-dimensional advection diffusion for potential temperature using potential temperature coordinates. The main advantage of this formulation is that the temporal evolution of the reference temperature profile is entirely due to the competition between effective diffusivity that is always positive definite, and the water mass transformation taking place at the surface, as in classical water mass analyses literature. These quantities are evaluated in numerical simulations of present day climate and global warming experiments. In this framework, the heat uptake in the global warming experiment is attributed to the increase of surface heat flux at low latitudes, its decrease at high latitudes and to the redistribution of heat toward cold temperatures made by diffusive flux.

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