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Batch Reactor (batch + reactor)
Kinds of Batch Reactor Selected AbstractsBiological Treatment of Sludge from a Recirculating Aquaculture System Using a Sequencing Batch ReactorJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2005Ramaraj Boopathy [source] Prediction of Chain Length Distribution of Polystyrene Made in Batch Reactors with Bifunctional Free-Radical Initiators Using Dynamic Monte Carlo SimulationMACROMOLECULAR REACTION ENGINEERING, Issue 3 2007Ibrahim M. Maafa Abstract The objective of this paper is to present a dynamic Monte Carlo model that is able to simulate the polymerization of styrene with bifunctional free-radical initiators in a batch reactor. The model can predict the dynamic evolution of the chain length distribution of polystyrene in the reactor. The model includes all relevant polymerization mechanistic steps, including chemical and thermal radical generation, and diffusion-controlled termination. The model was applied to styrene polymerization and the Monte Carlo estimates for chain length averages were compared to those obtained with the method of moments. Excellent agreement was obtained between the two methods. Although styrene polymerization was used as a case study, the proposed methodology can be easily extended to any other polymer type made by free-radical polymerization. [source] Ultrasonic treatment of waste activated sludgeENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2006Raf Dewil Abstract Activated sludge processes are key technologies to treat wastewater. These biological processes produce huge amounts of waste activated sludge (WAS), now commonly called biosolids. Mechanical, thermal, and/or chemical WAS conditioning techniques have been proposed to reduce the sludge burden. The ultrasonic treatment of WAS is quite novel. The present paper reports on extensive investigations using an ultrasonic treatment of WAS, to study its potential to meet one or all of four objectives: (1) reduce WAS quantities; (2) achieve a better dewaterability; (3) provoke a release of soluble chemical oxygen demand (COD) from the biosolids, preferably transformed into biodegradable organics; and (4) possibly destroy the filamentous microorganisms responsible for sludge bulking. Although meeting these objectives would help to solve the problems cited, the energy consumption could be a considerable drawback: the paper will thus assess whether all or some objectives are met, and at what operational cost. A literature survey defines the occurring phenomena (cavitation) and the important operation parameters [such as frequency, duration, specific energy input (SE)]. The experiments are carried out in a batch reactor of volume up to 2.3 L. The ultrasonic equipment consisted of a generator, a converter, and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different kinds of sludge were tested, with different concentrations of dry solids (DS) between approximately 3.5 and 14 g DS/L WAS. Ultrasonic energy was introduced in a continuous manner (against possible pulsed operation). The major operational parameters studied include duration of the ultrasonic treatment and specific energy input. The applied frequency was set at 20 kHz. The release of COD from the WAS phase into the filtrate phase is a function of the specific energy input with yields of nearly 30% achievable at SE values of 30,000 kJ/kg DS. A major fraction of the COD is transformed into biodegradable organics (BOD). The reduction in DS fraction of the sludge is proportional to the COD release rates. Although the DS content is reduced, the dewaterability of the sludge is not improved. This reflects itself in increased filtration times during vacuum filtration and in increased values of the capillary suction time (CST). This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area: more surface water is bound (CST increases) and the filterability decreases as a result of clogging of the cake. To reach the same dryness as for the untreated cake, the required dosage of polyelectrolyte is nearly doubled when the SE of the ultrasound treatment is increased from 7500 to 20,000 kJ/kg DS. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. The release of soluble COD and BOD certainly merit further research. © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source] Monitoring bacterial and archaeal community shifts in a mesophilic anaerobic batch reactor treating a high-strength organic wastewaterFEMS MICROBIOLOGY ECOLOGY, Issue 3 2008Changsoo Lee Abstract Shifts in bacterial and archaeal communities, associated with changes in chemical profiles, were investigated in an anaerobic batch reactor treating dairy-processing wastewater prepared with whey permeate powder. The dynamics of bacterial and archaeal populations were monitored by quantitative real-time PCR and showed good agreement with the process data. A rapid increase in bacterial populations and a high rate of substrate fermentation were observed during the initial period. Growth and regrowth of archaeal populations occurred with biphasic production of methane, corresponding to the diauxic consumption of acetate and propionate. Bacterial community structure was examined by denaturing gel gradient electrophoresis (DGGE) targeting 16S rRNA genes. An Aeromonas -like organism was suggested to be mainly responsible for the rapid fermentation of carbohydrate during the initial period. Several band sequences closely related to the Clostridium species, capable of carbohydrate fermentation, lactate or ethanol fermentation, and/or homoacetogenesis, were also detected. Statistical analyses of the DGGE profiles showed that the bacterial community structure, as well as the process performance, varied with the incubation time. Our results demonstrated that the bacterial community shifted, reflecting the performance changes and, particularly, that a significant community shift corresponded to a considerable process event. This suggested that the diagnosis of an anaerobic digestion process could be possible by monitoring bacterial community shifts. [source] Synthesis of Nanophased Metal Oxides in Supercritical Water: Catalysts for Biomass ConversionINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2006Caroline Levy Nanoparticles of zinc oxide-based materials (ZnO, ZnAl2O4) with various morphologies were synthesized in supercritical water (SCW) with a flow-type apparatus and in sub- and supercritical water with a batch reactor. In the flow-type apparatus, smaller particles were obtained. Depending on the precursors, the morphology of crystallites is rod, hexagonal, or rectangular shaped. ZnAl2O4 was synthesized with a high specific surface area (SBET) reaching 210 m2/g and nanocrystallite sizes ,10 nm. The KOH concentration played a major role in the formation of ZnO and ZnAl2O4 phases. Then, the synthesized materials were used as catalysts for the biomass conversion by the oxidation process to produce hydrogen. [source] Kinetic study of transesterification of methyl acetate with n -butanol catalyzed by NKC-9INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2009Baoyun Xu The transesterification of methyl acetate and n -butanol catalyzed by cation-exchange resin, NKC-9, was studied in this work to obtain the reaction kinetics. The experiments were carried out in a stirred batch reactor at different temperatures (328.15, 333.15, 338.15, 343.15, 345.15 K) under atmospheric pressure. The effects of temperature, molar ratio of reactants, and catalyst loading on the reaction rate were researched under the condition of eliminating the effect of diffusion. The experimental data were correlated with a kinetic model based on the pseudo-homogeneous catalysis. The kinetic equation describing the reaction catalyzed by NKC-9 was developed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 101,106, 2009 [source] Kinetics and mechanisms of transalkylation and disproportionation of meta -diethylbenzene by triflic acid catalystINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 11 2003S. M. Al-Zahrani The kinetics of transalkylation and isomerization of meta -diethylbenzene in the presence of benzene using triflic acid as a catalyst has been investigated. High catalytic activity of the triflic acid catalyst was observed in homogeneous liquid-phase reactions. On the basis of the product distribution obtained, transalkylation, disproportionation, and isomerization reactions have been considered and the main product of the reaction was ethylbenzene. These reactions are conducted in a closed liquid batch reactor with continuous stirring under dry nitrogen and atmospheric pressure over the temperature range of 288,308 K. The main transalkylation, disproportionation, and isomerization reactions occurred simultaneously and were considered as elementary reactions. The apparent activation energy of the transalkylation reaction was found to be 35.5 kJ/mol, while that of disproportionation reaction was 42.3 kJ/mol. The reproducibility of the experimental product distribution occurred with an average relative error of ±2%. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 555,563, 2003 [source] Linear PI control of batch exothermic reactors with temperature measurementINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3 2006Jose Alvarez-Ramirez Abstract A wide variety of speciality materials and fine chemicals such as plastics, pharmaceutical and microelectronics components are produced in batch reactors. The nonlinear, transient and finite-time features of the batch reactors give rise to complex process and control design problems. In particular, the safe operation of exothermic reactors depends on the adequate functioning of a temperature tracking controller, and to a good extent, the same is true for the attainment of a suitable compromise between productivity and product quality attributes. While the stabilization problem of continuous exothermic chemical reactors has been recently addressed with rigorous asymptotic-stability methods, the same kind of studies have not yet been performed for the finite-time batch reactor case. In this paper, the problem of designing a temperature tracking controller for an exothermic batch reactor, with n species and m reactions, is addressed under the following premises: (i) only the reactor temperature is measured, (ii) the (typically uncertain) reaction rate and heat exchange nonlinear functions are unknown, (iii) the controller must be linear and easy to tune, and (iv) the closed-loop reactor motion must be stable in a suitable sense. The combination of industrial-oriented inventory control concepts in conjunction with singular perturbation results yields a linear controller with a combined feedforward-PI feedback structure, antireset windup scheme, and conventional-like tuning rules. The controller: (i) tracks, arbitrarily fast and close, a prescribed temperature trajectory, with admissibly deviated concentration motions, and (ii) quickly recovers the behaviour of an exact model-based nonlinear I/O linearizing controller. The proposed design is put in perspective with the geometric and IMC nonlinear control approaches. Copyright © 2005 John Wiley & Sons, Ltd. [source] Combined Application of Galactose Oxidase and ,- N -Acetylhexosaminidase in the Synthesis of Complex Immunoactive N -Acetyl- D -galactosaminidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005Pavla Fialová Abstract A high-yield preparatory procedure for the synthesis of p -nitrophenyl 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranoside (2) using the galactose oxidase from Dactylium dendroides in a batch reactor was developed. Enzymatic recognition of this aldehyde and the respective uronic acid 3 obtained by NaClO2 oxidation was studied using a set of 36 fungal ,- N -acetylhexosaminidases from Acremonium, Aspergillus, Penicillium and Talaromyces genera. The aldehyde 2 was readily hydrolysed by all tested ,- N -acetylhexosaminidases but neither the uronic acid 3 nor its methyl ester 4 were accepted. Molecular modelling with docking into the active centre of the ,- N -acetylhexosaminidase from Aspergillus oryzae revealed that the aldehyde 2 is processed as a C-6 geminal diol by the enzyme. The aldehyde 2 was tested for transglycosylation reactions using GlcNAc as an acceptor. The ,- N -acetylhexosaminidase from Talaromyces flavus gave the best yields (37%) of the transglycosylation product 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranosyl-(1,4)-2-acetamido- 2-deoxy- D -glucopyranose, which was oxidised in situ to yield the final product 2-acetamido-2-deoxy-,- D -galactopyranosyluronic acid-(1,4)-2-acetamido-2-deoxy- D -glucopyranose (6). Compounds 3 and 6 were shown to be high-affinity ligands for two natural killer cell activation receptors, NKR-P1A and CD69. For the latter receptor they turned out to be among the best ligands described so far. This increase was obviously due to the presence of a carboxy moiety. [source] Relationship between inactivation kinetics of a Listeria monocytogenes suspension by chlorine and its chlorine demandJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2004R. Virto Abstract Aims:, Chlorine demand by Listeria monocytogenes cells and inactivation of L. monocytogenes by chlorine (0·6,1·0 mg l,1) at different temperatures (4, 20 and 30°C) have been investigated in a batch reactor. Methods and Results:, Chlorine demand depended on the microbial concentration and was independent on the initial chlorine concentration and temperature. Chlorine decay was modelled by the addition of two first-order decay equations. Inactivation of L. monocytogenes by chlorine depended on the initial microbial concentration, initial chlorine concentration and temperature. A mathematical model based on a biphasic inactivation properly described survival curves of L. monocytogenes and a tertiary model was developed that satisfactorily predicted the inactivation of L. monocytogenes by different concentrations of initial chlorine at different temperatures. Conclusions:, Both available chlorine decay and inactivation of L. monocytogenes by chlorine were biphasic and can be modelled by a two-term exponential model. Significance and Impact of the Study:, The biphasic nature of survival curves of L. monocytogenes did not reflect the effect of a change of available chlorine concentration during the treatment. The microbial inactivation was caused by successive reactions that occur after the consumption of the chlorine by the bacterial cell components. [source] Aerobic granules for low-strength wastewater treatment: formation, structure, and microbial communityJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2009Shu-Guang Wang Abstract BACKGROUND: To validate the possibility of aerobic granulation at a lower organic loading rate (OLR) than 2 kg COD m,3 day,1 (GS 1) in a sequencing batch reactor (SBR), the formation, structure, and microbial community of granular sludge (GS) were investigated. RESULTS: The overall experimental process involved the following stages: acclimation, granulation, maturation, and stabilization. The optical microscopic showed the structural changes from fluffy activated sludge (AS) to GS and scanning electron microscope (SEM) examination revealed that GS 1 was irregular filamentous aggregates composed mainly of various filamentous species, while the aerobic granules cultivated at OLR 1.68,4.20 kg COD m,3 day,1 (GS 2) was mycelial pellets consisting of fungi and filamentous microorganisms. A Biolog Ecoplate analysis indicated that significant differences existed between the microbial community structure and the substrate's utilization of AS and different GS samples. CONCLUSION: GS 1 was achieved and different from GS 2 in the formation, structure, and microbial community. Aerobic granulation with low strength wastewater is of importance for the full-scale application of this technology. Copyright © 2009 Society of Chemical Industry [source] Study of saline wastewater influence on activated sludge flocs through automated image analysisJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2009Daniela P Mesquita Abstract BACKGROUND: In activated sludge systems, sludge settling ability is considered a critical step in effluent quality and determinant of solid,liquid separation processes. However, few studies have reported the influence of saline wastewater on activated sludge. This work aims the evaluation of settling ability properties of microbial aggregates in a sequencing batch reactor treating saline wastewaters of up to 60 g L,1 NaCl, by image analysis procedures. RESULTS: It was found that the sludge volume index (SVI) decreased with salt content up to 20 g L,1, remaining somewhat stable above this value. Furthermore, it was found that between the first salt concentration (5 g L,1) and 20 g L,1 aggregates suffered a strong deflocculation phenomenon, leading to a heavy loss of aggregated biomass. Regarding SVI prediction ability, a good correlation coefficient of 0.991 between observed and predicted SVI values was attained. CONCLUSION: From this work the deflocculation of aggregated biomass with salt addition due to pinpoint floc formation, dispersed bacteria growth and protozoa absence could be established. With respect to SVI estimation, and despite the good correlation obtained, caution is advisable given the low number of SVI data points. Copyright © 2008 Society of Chemical Industry [source] Development of a mathematical model for Bacillus circulans growth and alkaline protease production kineticsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2009Chaganti Subba Rao Abstract BACKGROUND: An unstructured mathematical model was developed to understand information on the relationship between Bacillus circulans growth and metabolism-related protease production (using logistic and Luedeking,Piret equations respectively) in a batch reactor with respect to glucose consumption and fermentation time. The objective was to develop an indispensable tool for the optimisation, control, design and analysis of alkaline protease production. RESULTS: Biomass growth and enzyme production titres changed with a change in substrate concentration. Modelling analysis of biomass and enzyme production titres at different substrate concentrations revealed significant accuracy in terms of statistical consistency and robustness with respect to fermentation kinetic profiles. CONCLUSION: With the B. circulans strain used, an economic protease yield (2837 × 103 U g,1) with respect to biomass and glucose ratio was achieved at low substrate concentration (10 g L,1). The developed model could be effectively utilised for designing, controlling and up-scaling the protease production process in high-density fermentation in selected bioreactors with statistical consistency. Copyright © 2008 Society of Chemical Industry [source] Influence of COD:N:P ratio on dark greywater treatment using a sequencing batch reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2008Vijayaraghavan Krishnan Abstract The recycling of greywater is an integral part of a water management system owing to the scarcity of fresh water resources. This article explores the effectiveness of an aerobic sequencing batch reactor in treating nutrient-deficit and nutrient-spiked dark greywater for agricultural reuse. The dark greywater in the present investigation had a COD:N:P ratio of 100:1.82:0.76, while the preferred ratio for biological oxidation is 100:5:1 (COD, chemical oxygen demand). The aerobic oxidation of nutrient-deficit and nutrient-spiked dark greywater with a COD:N:P ratio of 100:2.5:0.5; 100:3.5:0.75 and 100:5:1 resulted in outlet COD values of 64; 35; 15 and 12 mg L,1, with a corresponding BOD5 value of 37; 22; 10 and 8 mg L,1 at 36 h hydraulic retention time (HRT). Hence treatment of nutrient-added dark greywater at a COD:N:P ratio 100:3.5:0.75 and 100:5:1 for 36 h HRT complied with the Malaysian discharge standards for agricultural activities. Treated greywater has the potential for consideration as a resource, since it can be used as a supplement or replacement for potable water in landscape irrigation and other agricultural activities in rural and urban areas. Moreover, the level of greywater treatment is dictated by the final water quality requirement. Copyright © 2008 Society of Chemical Industry [source] Storage of biodegradable polymers by an enriched microbial community in a sequencing batch reactor operated at high organic load rateJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2005Davide Dionisi Abstract The production of polyhydroxyalkanoates (PHAs) from organic acids by mixed bacterial cultures using a process based on aerobic enrichment of activated sludge, that selects for mixed microbial cultures able to store PHAs at high rates and yields, is described. Enrichment resulted from the selective pressure established by periodic feeding the carbon source in a sequencing batch reactor (SBR); a mixture of acetic, lactic and propionic acids was fed at high frequency (2 hourly), high dilution rate (1 d,1), and at high organic load rate (12.75 g chemical oxygen demand (COD) L,1 d,1). The performance of the SBR was assessed by microbial biomass and PHA production as well as the composition and polymer content of the biomass. A final batch stage was used to increase the polymer concentration of the excess sludge produced in the SBR and in which the behaviour of the biomass was investigated by determining PHA production rates and yields. The microbial biomass selected in the SBR produced PHAs at high rate [278 mg PHAs (as COD) g biomass (as COD),1 h,1, with a yield of 0.39 mg PHAs (as COD) mg removed substrates (as COD),1], reaching a polymer content higher than 50% (on a COD basis). The stored polymer was the copolymer poly(3-hydroxybutyrate/3-hydroxyvalerate) [P(HB/HV)], with an HV fraction of 18% mol mol,1. The microbial community selected in the SBR was analysed by DGGE (denaturing gradient gel electrophoresis). The operating conditions of the SBR were shown to select for a restricted microbial population which appeared quite different in terms of composition with respect to the initial microbial cenosis in the activated sludge used as inoculum. On the basis of the sequencing of the major bands in the DGGE profiles, four main genera were identified: a Methylobacteriaceae bacterium, Flavobacterium sp, Candidatus Meganema perideroedes, and Thauera sp. The effects of nitrogen depletion (ie absence of growth) and pH variation were also investigated in the batch stage and compared with the SBR operative mode. Absence of growth did not stimulate higher PHA production, so indicating that the periodic feed regime fully exploited the storage potential of the enriched culture. Polymer production rates remained high between pH 6.5 and 9.5, whereas the HV content in the stored polymer strongly increased as the pH value increased. This study shows that polymer composition in the final batch stage can readily be controlled independently from the feed composition in the SBR. Copyright © 2005 Society of Chemical Industry [source] Kinetics of esterification of palmitic acid with isopropanol using p -toluene sulfonic acid and zinc ethanoate supported over silica gel as catalystsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2004Roomana Aafaqi Abstract Kinetic data on the esterification of palmitic acid with isopropanol were obtained using homogeneous (para -toluene sulfonic acid, p -TSA) and heterogeneous (zinc ethanoate coated on silica gel, ZnA/SG) catalysts in a batch reactor. The ZnA/SG catalyst was prepared using a sol,gel technique. The esterification reaction was studied at different reaction temperatures (373,443 K), initial reactants molar ratio (1,5), catalyst loading (1,5 gcat dm,3) and water concentration in feed (0,15 vol%). A power law rate equation was used for homogeneous kinetics analysis. The Langmuir Hinshelwood Hougen Watson (LHHW) model was used for heterogeneous kinetics. The kinetic parameters of both models were obtained using Polymath software. The reaction parameters were used to obtain simulated values of conversion for both catalytic systems. The simulated values were compared with the experimental values and were in good agreement. Copyright © 2004 Society of Chemical Industry [source] Kinetics and mechanistic analysis of caustic magnesia hydrationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2004Sônia DF Rocha Abstract The kinetics of magnesia hydration to produce magnesium hydroxide is crucial for process design and control, and for the production of an Mg(OH)2 powder with desirable particle morphology. In this study, highly pure magnesia has been hydrated in a batch reactor. The effects of the following variables were evaluated experimentally: temperature (308,363 K), reaction time (0.5,5 h), initial slurry density (1,25%wt) and particle size in the ranges ,212 + 75 µm and ,45 + 38 µm. Experimental data indicate increasing magnesia hydration rates with increasing temperature, as expected. In addition, it has been observed that the hydration of magnesia increases significantly up to about 4,5%wt initial slurry density, stabilising afterwards. On the other hand, the reaction was almost unaffected when magnesia with different particle sizes were hydrated because of similar specific surface areas involved. A reaction mechanism to explain the oxide dissolution and the hydroxide precipitation has been proposed, assuming no significant change in the initial solids size and dissolution rate as the controlling step. The calculated activation energy value of 62.3 kJ mol,1 corroborates the mechanism proposed in this study and compares well with values previously reported in the literature. Copyright © 2004 Society of Chemical Industry [source] Modeling an electrochemical process to remove Cr(VI) from rinse-water in a stirred reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2003Miriam G Rodríguez Abstract Experimental studies were developed in a batch reactor (16,dm3), to obtain the kinetic model of Cr(VI) removal by means of an electrochemical process. An overall kinetic model was obtained and experimentally validated in a continuous stirred electrochemical reactor (16,dm3) with synthetic and industrial wastewater. To develop the mathematical model of the continuous reactor in relation to the Cr(VI) and Fe(II) concentration in the solution, a classical mass balance procedure was performed. The Cr(VI) concentration in the electrochemically-treated waters was less than 0.5,mg,dm,3. In the electrochemical process the Cr(VI) reduction is caused by the Fe(II) released from the anode due to the electric current applied, by the Fe(II) released for the dissolution (corrosion) of the electrodes due to the acidic media, and by reduction at the cathode. During the process, reduction from Fe(III) to Fe(II) occurs. All of these different reactions cause a diminution in the quantity of sludge generated. Finally, it was found that due to the slow rate of reduction of Cr(VI) during the first part of the process it is necessary to develop a method of control to apply the process in a continuous industrial system. © 2003 Society of Chemical Industry [source] Biodegradability of slaughterhouse wastewater with high blood content under anaerobic and aerobic conditionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2003Rodrigo del Pozo Abstract In this work, the biodegradability of wastewater from a slaughterhouse located in Ke,an, Turkey, was studied under aerobic and anaerobic conditions. A very high total COD content of 7230,mg,dm,3 was found, due to an inefficient blood recovery system. Low BOD5/COD ratio, high organic nitrogen and soluble COD contents, were in accordance with a high blood content. A respirometry test for COD fractionation showed a very low readily biodegradable fraction (SS) of 2%, a rapidly hydrolysable fraction (SH) of 51%, a slowly hydrolysable fraction (XS) of 33% and an inert fraction of 6%. Kinetic analysis revealed that hydrolysis rates were much slower than these of domestic sewage. The results underlined the need for an anaerobic stage prior to aerobic treatment. Tests with an anaerobic batch reactor indicated efficient COD degradation, up to around 80% removal. Further anaerobic degradation of the remaining COD was much slower and resulted in the build up of inert COD compounds generated as part of the metabolic activities in the anaerobic reactor. Accordingly, it is suggested that an appropriate combination of anaerobic and aerobic reactors would have to limit anaerobic degradation to around 80% of the tCOD and an effluent concentration above 1000,mg,dm,3, for the optimum operation of the following aerobic stage. © 2003 Society of Chemical Industry [source] Simultaneous organic carbon and nitrogen removal in an SBR controlled at low dissolved oxygen concentrationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001Peng Dangcong Abstract Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8,mg,dm,3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4,kg COD m,3 d,1 and 0.24,kg NH3 -N m3 d,1) and efficiencies (COD, NH3 -N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry [source] APPLICATION OF EXPERIMENTAL DESIGN METHOD TO THE OIL EXTRACTION FROM OLIVE CAKEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2009SMAIL MEZIANE ABSTRACT Olive cake is an important solid waste of the olive oil production. It still contains a certain quantity of oil that can be recovered by means of solvent extraction. In this study, two-level full factorial design was performed to evaluate the effects of four variables and their interactions on the oil extraction by the ethanol 96.0% in a batch reactor. The variables included size of particles, temperature, and time of contact and solvent-to-solids ratio. The statistical analysis of the experimental data showed that the extracted oil mass depends on all the examined variables. It also depends on the interactions between size of particles and solvent-to-solid ratio and size of particles and temperature. The experimental data were in good agreement with those predicted by the model. PRACTICAL APPLICATIONS Olive cake is solid waste of the olive oil industry that is available in large amounts in many Mediterranean countries and at very low cost. It can be treated or valorized, enabling at the same time the solution to environmental problems caused by the olive oil production process. The economic interest that it presents is especially because of the residual oil that it contains and that can be recovered by solvent extraction. However, this solid,liquid extraction depends on several parameters: the ones inherent to the products (structure and properties of the sample, nature of extraction solvent); and the others to the extraction process (time of contact, temperature of extraction, solvent-to-solid ratio, stirring velocity). The experimental design method enables to determine the most important variables and their interaction in the extraction process at the same time performing a low number of experiments. [source] Lipase-mediated Acidolysis of Fully Hydrogenated Soybean Oil with Conjugated Linoleic AcidJOURNAL OF FOOD SCIENCE, Issue 1 2004J. Ortega ABSTRACT: Interesterification (acidolysis) of fully hydrogenated soybean oil (melting point = 69.9 °C) with conjugated linoleic acid (CLA) was carried out in a batch reactor at 75 °C. Lipases from Candida antarctica, Rhizomucor miehei, Pseudomonas sp., and Thermomyces lanuginosus were used at 5% (wt/wt) of the total substrate load. The lipase from Rhizomucor miehei produced the fastest reaction rates, and the greatest extent of incorporation of CLA residues in acylglycerols was achieved in 12 h. Lipases from C. antarctica and T. lanuginosus produced slower initial rates, and maximum extents of incorporation of CLA residues were achieved in 24 h. The lipase from Pseudomonas sp. produced the slowest initial rate. The corresponding maximum extent of incorporation was reached in 48 h. Differential scanning calorimetry analysis of the triacylglycerol (TAG) fractions produced by C. antarctica, R. miehei, and T. lanuginosus lipases after purification by solid phase extraction showed little variation in melting point (60.4 °C, 62.8 °C, and 60.1 °C, respectively). By contrast, the corresponding TAG fraction produced by the Pseudomonas sp. lipase melted at 48.4 °C. The positional distribution of the TAGs produced by the lipase from Pseudomonas sp. differed appreciably from those produced by the other enzymes. [source] Inactivation Kinetics of Foodborne Spoilage and Pathogenic Bacteria by OzoneJOURNAL OF FOOD SCIENCE, Issue 3 2000J.-G. Kim ABSTRACT: Ozone was tested against Pseudomonas fluorescens, Escherichia coli O157:H7, Leuconostoc mesenteroides, and Listeria monocytogenes. When kinetic data from a batch reactor were fitted to a dose-response model, a 2-phased linear relationship was observed. A continuous ozone reactor was developed to ensure a uniform exposure of bacterial cells to ozone and a constant concentration of ozone during the treatment. Survivors plots in the continuous system were linear initially, followed by a concave downward pattern. Exposure of bacteria to ozone at 2.5 ppm for 40 s caused 5 to 6 log decrease in count. Resistance of tested bacteria to ozone followed this descending order: E. coli O157:H7, P. fluorescens, L. mesenteroides, and L. monocytogenes. [source] Nitration of nitrobenzene at high-concentrations of sulfuric acid: Mass transfer and kinetic aspectsAICHE JOURNAL, Issue 3 2010M. Rahaman Abstract This article reports studies on mass transfer and kinetics of nitration of nitrobenzene at high concentrations of sulfuric acid in a batch reactor at different temperatures. The effects of concentration of sulfuric acid, speed of stirring, and temperature on mass transfer coefficient were investigated. The kinetics of nitration under homogenized conditions was studied at different sulfuric acid concentrations at these temperatures. The reaction rate constants were determined. The variation of rate constant with sulfuric acid concentration was explained by the Mc function. The activation energies of the reactions were determined from the Arrhenius plots. The regimes of the reactions were determined using the values of the mass transfer coefficients and the reaction rate constants. A model was developed for simultaneous mass transfer and chemical reaction in the aqueous phase. The yields of the three isomers of dinitrobenzene were determined, and the variation of isomer distribution with sulfuric acid concentration and temperature was analyzed. This work demonstrates that more than 90% conversion of nitrobenzene is possible at high-sulfuric acid concentrations resulting in high yield of the product even at moderate temperatures and at low speeds of stirring. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Modeling and simulation of the formation and utilization of microbial products in aerobic granular sludgeAICHE JOURNAL, Issue 2 2010Bing-Jie Ni Abstract A mathematical model is established to simulate the formation of extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (XSTO) in aerobic granular sludge. The sensitivity of these microbial products concentrations toward the key model parameters is analyzed. Independent experiments are conducted to find required parameter values and to test its predictive ability. The model is evaluated by using one-cycle operating experimental results of a lab-scale aerobic granule-based sequencing batch reactor (SBR) and batch experimental results. Results show that the model is able to describe the microbial product dynamics in aerobic granules and provide further insights into a granule-based SBR. The effect of the initial substrate and biomass concentrations on the formation of microbial products in aerobic granular sludge can therefore be analyzed by model simulation. A higher substrate concentration results in a greater concentration of EPS, SMP, and XSTO. An accumulation of biomass in the bioreactor leads to an increased production rate of EPS, SMP, and XSTO. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] A thermodynamic analysis of the activated sludge process: Application to soybean wastewater treatment in a sequencing batch reactorAICHE JOURNAL, Issue 10 2009Bing-jie Ni Abstract A bioenergetic methodology was integrated with a modified activated sludge model No.1 (ASM1) to analyze the activated sludge process, with the treatment of soybean-processing wastewater as an example. With the bioenergetic methodology established by McCarty and coworkers, the microbial yield was predicted and the overall stoichiometrics for biological reactions involving the key chemical and biological species in activated sludge were established. These obtained parameters were related to the ASM1 model, which was modified after coupling the biological reactions in activated sludge with electron balances. This approach was able to approximately describe the treatment of soybean wastewater by activated sludge in a sequencing batch reactor in terms of substrate utilization, biomass growth, and the elector acceptor consumption. Such an attempt provides useful information for accurate modeling of the complex activated sludge process. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Modeling and simulation of the sequencing batch reactor at a full-scale municipal wastewater treatment plantAICHE JOURNAL, Issue 8 2009Bing-Jie Ni Abstract In this work, we attempted to modify the Activated Sludge Model No.3 and to simulate the performance of a full-scale sequencing batch reactor (SBR) plant for municipal wastewater treatment. The long-term dynamic data from the continuous operation of this SBR plant were simulated. The influent wastewater composition was characterized using batch measurements. After incorporating all the relevant processes, the sensitivity of the stoichiometric and kinetic coefficients for the model was thoroughly analyzed prior to the model calibration. The modified model was calibrated and validated with the data from both batch- and full-scale experiments. Model predictions were compared with routine data in terms of chemical oxygen demand, NH4+ -N and mixed liquid volatile suspended solids in the SBR, combined with batch experimental data under different conditions. The model predictions match the experimental results well, demonstrating that the model is appropriate to simulate the performance of a full-scale wastewater treatment plant even operated under perturbation conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Quantitative framework for reliable safety analysisAICHE JOURNAL, Issue 1 2002Haitao Huang The effectiveness of any methodology used to identify hazards in chemical processes affects both safety and economics. To achieve maximum safety at minimum cost, a conservative, but realistic, analysis must be carried out. An approach to hazard identification is proposed based on a detailed process model which includes nonlinear dynamics and uncertainty. A new modeling framework, the region-transition model (RTM), is developed, which enables the simulation of regions of the operating space through an extension of the hybrid state transition system formalism. The RTM is illustrated on a nonlinear batch reactor with parameter uncertainty. A safety-verification algorithm identifies regions of the input space (initial conditions and external inputs) which guarantee safe operation. The algorithm is successfully applied to three examples: a tank with overflow and underflow, a batch reactor with an exothermic reaction, and a CSTR with feed preheating. [source] Surfactant assisted polymerization of tetrafluoroethylene in supercritical carbon dioxide with a pilot scale batch reactorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2008Alberto Giaconia Abstract Chain-free radical polymerization of tetrafluoroethylene (TFE) was carried out in supercritical carbon dioxide (scCO2), at 50 °C and 121,133 bar, with tertiary -amyl-per-pivalate as a free radical initiator, using a 5-L pilot scale batch reactor. Experiments were carried out both in the absence and in the presence of perfluoropolyether (PFPE) carboxylate surfactants. Stabilizers were employed under the free acid form and as sodium and calcium salts. An expanded fibrillated poly(TFE) was obtained in all experiments. In the case of surfactant-free polymerizations, the product was mainly constituted by irregular shape macroparticles having size in the range 200,500 ,m. Quite interestingly, when the free acid surfactant was used, a clear acceleration of the polymerization rate was observed and smaller polymer particles with more regular quasi-spherical morphology were obtained. Melt fusion crystallinity of as-polymerized poly(TFE) seemed not substantially affected by the presence of the stabilizers and was rather high (80,86%) suggesting that polymerization mainly occurs at polymer particle surface. All these elements suggest that FLUOROLINK® 7004H PFPE carboxylic acid decreases coagulation of primary polymer particles leading to an increase in polymer surface area. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 257,266, 2008 [source] Kinetics of the batch cationic emulsion polymerization of styrene: A comparative study with the anionic caseJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2006Jose Ramos Abstract An in-depth study on the kinetics of the cationic emulsion polymerization of styrene in a batch reactor is presented. This study is focused on the effect of the amount of the cationic surfactant dodecyltrimethylammonium bromide (DTAB), using two different cationic initiators: 2,2,-azobisisobutyramidine dihydrochloride (AIBA), 2,2,-azobis (N,N,-dimethyleneisobutyramidine) dihydrochloride (ADIBA), on kinetics and colloidal features such as conversion, number of particles, number average of radicals per particle, mean particle diameter, and particle size distribution (PSD) of the polystyrene latices obtained by emulsion polymerization in a batch reactor. Furthermore, the results of the cationic emulsion polymerization were compared with its homologous anionic case. Using DTAB as cationic surfactant an expected increase in the total rate of polymerization was observed when the DTAB concentration increased. However, the total number of particles increased much more than in the anionic system. On the other hand, a dependence on the particle size of the rate of polymerization per particle together with the average number of radicals per particle was found. These differences between cationic and anionic emulsion polymerizations were explained taking into account the limited particle coagulation observed with cationic surfactants, and the high rate of radical formation of cationic initiators. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4461,4478, 2006 [source] | ||||||||||||||||||||||||||||||||||