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A significant number of different types of damage to structural materials, as well as various scenarios of their accumulation, up to destruction, require not only the use of a significant set of experimental methods and the methods of theoretical materials science and molecular physics, but also for developing appropriate mathematical models. These models perform two functions. On the one hand, they make it possible to give a reasonable interpretation of complicated processes, and, on the other hand, they can forecast the evolution of the material under specific operating conditions. Some features characterizing the description of material degradation and destruction based on kinetic approaches are considered. [ABSTRACT FROM AUTHOR]

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The hydrogen-producing bacteria SP4 and SP6 were isolated from the compost and identified by 16S rRNA gene sequencing as Clostridium butyricum and Clostridium beijerinckii , respectively. A comparative study on the biohydrogen-producing activity of the isolated strains was carried out using mono-, di- and tri-saccharides belonging to both hexoses (maltose, glucose, mannose, fructose, lactose, galactose, sucrose, raffinose, cellobiose) and pentoses (xylose). To assess the biotechnological significance, real wastewater rich in sugars (cheese whey, confectionery wastewater, sugar beet processing wastewater) was also used as a substrate. C. butyricum SP4 fermented sugars with a yield of 0.93–1.52 mol H 2 /mol hexose (pentose); the maximum yield was obtained from fructose, the minimum – from raffinose and cellobiose. The most preferred substrate for C. beijerinckii SP6 was sucrose with a yield of 1.76 mol H 2 /mol hexose, while cellobiose yielded only 0.64 mol H 2 /mol hexose. Overall, the efficiency of converting wastewater to H 2 by C. butyricum SP4 was also slightly lower (66–93 ml H 2 /g chemical oxygen demand (COD)) than that of C. beijerinckii SP6 (76–103 ml H 2 /g COD). Even though the main soluble metabolite products (SMPs) for both isolates were acetate and butyrate, C. butyricum SP4 also produced a significant amount of ethanol (up to 21.5% of SMPs) and formate (up to 32.5% of SMPs), and C. beijerinckii SP6 – lactate (up to 25% of SMPs). A distinctive feature of C. beijerinckii SP6 was a significantly lower (almost 2 times) yield of SMPs, while C. butyricum SP4 had a higher rate of H 2 production according to the results obtained from the kinetic study using the modified Gompertz equation and the first order equation. Analysis of Spearman's rank correlation coefficients revealed a statistically significant relationship between the kinetic parameters of H 2 production and the concentration of butyrate and the final pH of the medium for C. butyricum SP4, and with the concentration of ethanol for C. beijerinckii SP6. These findings provide valuable information on the metabolic capabilities of the most studied hydrogen-producing representatives of the Clostridium genus for their use in optimizing the technology for biohydrogen production by dark fermentation of various organic wastes. [ABSTRACT FROM AUTHOR]

A scientific substantiation of solid-phase feedstock choice and preparation has been carried out, and the thermodynamic and kinetic aspects of solid-state hydride synthesis (SHS) of metal products have been analyzed using the nickel dichloride reduction as an example. The preliminary dehydration modes and methods for controlling the complete removal of crystalline water from chloride raw materials and Olenegorsk superconcentrate, which is natural oxide raw material, are described. Conditions, including initial solid chloride particle sizes, are established under which diffusion complications of reduction to metal in methyldichlorosilane vapor are minimized. Thermodynamic estimates of nickel chlorides and oxides reduction possibility, iron and copper with ammonia and methane at temperatures of 400-1000 K in equilibrium conditions have been carried out. It has been shown that the stoichiometric coefficients of the nickel dichloride in ammonia overall reduction reaction calculated by thermodynamic modeling are in agreement with experimental data. In contrast to the copper dichloride reduction, for nickel dichloride the formation of metal monochloride at the intermediate stage is uncharacteristic, which is associated with a higher thermal stability of nickel dichloride. The main kinetic regularities of the reduction of nickel, copper, and iron to metal under SHS conditions in ammonia, monosilane, and methane, as well as the nickel dichloride with methyldichlorosilane vapor and methane successive reduction, are considered. Approximation of experimental data by topochemical equations in a linear form showed that for reduction degrees a up to 0.7-0.8, these data are satisfactorily described by the Roginsky – Schultz equation. For a > 0,8 the “shrinking sphere” model works better, which confirms the localization of the solid-state reduction reaction at the interface, moves deep into the crystal with the formation of a of interlocked metal germs. The importance and prospects of the results obtained for the theory development of metallurgical processes, deep complex processing of natural iron oxide raw materials, metal products and new generation materials production, including superhydrophobic ones, are discussed. The relevance of the study from the point of view of applying the method of physical and chemical analysis to the study of complex heterogeneous metallurgical processes is noted.

Osmotic dehydration (OD) is one of the commonly used methods for preservation of red beetroot. However, it is a time-consuming process and microbial contamination may occur, resulting in flavor deterioration and market value reduction of products. The present study was aimed to verify whether pulsed pressure osmotic dehydration (PPOD), a newly developed non-thermal food process method can accelerate the impregnation efficiency, improve the quality of final products, and explore the mechanism involved. Results indicated that pulsed pressure of 250 kPa effectively improved the mass transfer of OD process and the following drying process. The Weibull model could describe the drying kinetics very well. The hardness of red beetroot decreased significantly (p < 0.05) during OD process and remained stable after drying process. In addition, the PPOD and constant pressure treatments could preserve the surface color. Preserved beetroots under the pulsed pressure of 250 kPa obtained the highest score on overall acceptability, indicating it was preferred for preserved red beetroot. In conclusion, PPOD was an efficient, economical, and sustainable impregnation method for red beetroot, and these results can serve as a theoretical underpinning for analyzing the involving mechanism and exploring the excellent control parameters of impregnation process in the PPOD food processing. [ABSTRACT FROM AUTHOR]

The main stage in the production of high-quality whiskey is the process of aging whiskey distillates in specially prepared oak containers, on which the bouquet of an alcoholic beverage is finally formed. During the aging process, water and distillate evaporate through the pores of the container, and recently it has been practiced to replace it with oxygen, reasonably believing that this approach leads to a reduction in the duration of the whiskey maturation procedure, without losing its quality characteristics, while this procedure in the technology of obtaining alcohol drink is by far the least studied and therefore of scientific interest to researchers. The objects of the study were young whiskey distillates (State standard 33281-2015) with an alcohol concentration of 50% with the addition of French oak chips "Sweet Vanilla" and "Sweet Coffee". Three samples of reagents were prepared for the analysis - the main experiment, control No. 1 and control No. 2. In the process of studying the kinetic regularities of the process of maturation of whiskey distillates when exposed to oxygen, a series of experiments was carried out, on the basis of which the results were obtained in the form of graphical and mathematical dependencies. Based on the analysis of the data obtained, the extraction mechanism was identified at various stages of the maturation of the object of study under permanent exposure to oxygen, and the influencing factors on the mass transfer process were determined, in particular, the activation energy, which, for example, is necessary to find the rational duration of this procedure. Analysis of the data obtained leads to the conclusion that they can be recommended for use in the engineering practice of whiskey production, while the indicated research results do not contradict known published data and are based on the provisions of the mass transfer theory. [ABSTRACT FROM AUTHOR]

The study evaluated the co-metabolism of nonylphenol polyethoxylate (NPEO) within a main substrate stream subjected to biodegradation in an activated sludge system. Peptone mixture simulating sewage was selected as the synthetic substrate. As a novel approach, the NPEO concentration was magnified to match the COD level of the peptone mixture, so that co-metabolism could be evaluated by respirometry and modeling. A sequencing batch reactor (SBR) set-up at high sludge age to also allow nitrification was operated for this purpose. A long acclimation phase was necessary to start NPEO biodegradation, which was completed with 15% residual by-products. Modeling of respirometric data could identify COD fractions of NPEO with corresponding process kinetics for the first time, where the biodegradation of by-products could be interpreted numerically as a hydrolysis mechanism. Nonylphenol diethoxylate (NP2EO) was observed as the major by-product affecting the biodegradation of NPEO, because NPEO and NP2EO accounted for 60 to 70% of the total soluble COD in the solution during the course of biological reactions. The co-metabolism characteristics basically defined NPEO as a substrate, with no appreciable inhibitory action on the microbial culture both in terms of heterotrophic and autotrophic activities. [ABSTRACT FROM AUTHOR]

The biomass valorisation of the invasive brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) is key to curbing the expansion of this invasive macroalga which is generating tonnes of biomass on southern Spain beaches. As a feasible alternative for the biomass management, anaerobic co-digestion is proposed in this study. Although the anaerobic digestion of macroalgae barely produced 177 mL of CH4 g−1 VS, the co-digestion with a C-rich substrate, such as the olive mill solid waste (OMSW, the main waste derived from the two-phase olive oil manufacturing process), improved the anaerobic digestion process. The mixture improved not only the methane yield, but also its biodegradability. The highest biodegradability was found in the mixture 1 R. okamurae—1 OMSW, which improved the biodegradability of the macroalgae by 12.9% and 38.1% for the OMSW. The highest methane yield was observed for the mixture 1 R. okamurae—3 OMSW, improving the methane production of macroalgae alone by 157% and the OMSW methane production by 8.6%. Two mathematical models were used to fit the experimental data of methane production time with the aim of assessing the processes and obtaining the kinetic constants of the anaerobic co-digestion of different combination of R. okamurae and OMSW and both substrates independently. First-order kinetic and the transference function models allowed for appropriately fitting the experimental results of methane production with digestion time. The specific rate constant, k (first-order model) for the mixture 1 R. okamurae- 1.5 OMSW, was 5.1 and 1.3 times higher than that obtained for the mono-digestion of single OMSW and the macroalga, respectively. In the same way, the transference function model revealed that the maximum methane production rate (Rmax) was also found for the mixture 1 R. okamurae—1.5 OMSW (30.4 mL CH4 g−1 VS day−1), which was 1.6 and 2.2 times higher than the corresponding to the mono-digestions of the single OMSW and sole R. okamurae (18.9 and 13.6 mL CH4 g−1 VS day−1), respectively. [ABSTRACT FROM AUTHOR]

Cerium Ce(III) is one of the major pollutants contained in wastewater generated during Ce(III) mining. However, the effect(s) of Ce(III) on the functional genera responsible for removing nitrogen biologically from wastewater has not been studied and reported. In this study, the effects of Ce(III) on aspects of partial-nitritation-(PN) process including ammonia oxidation rate (AOR), process kinetics, and microbial activities were investigated. It was found that the effect of dosing Ce(III) in the PN system correlated strongly with the AOR. Compared to the control, batch assays dosed with 5 mg/L Ce(III) showed elevated PN efficiency of about 121%, an indication that maximum biological response was feasible upon Ce(III) dose. It was also found that, PN performance was not adversely affected, given that Ce(III) dose was ≤20 mg/L. Process kinetics investigated also suggested that the maximum Ce(III) dose without any visible inhibition to the activities of ammonium oxidizing bacteria was 1.37 mg/L, but demonstrated otherwise when Ce(III) dose exceeded 5.63 mg/L. Compared to the control, microbes conducted efficient Ce(III) removal (averaged 98.66%) via biosorption using extracellular polymeric substances (EPS). Notably, significant deposits of Ce(III) was found within the EPS produced as revealed by SEM, EDX, CLSM and FTIR. 2-dimensional correlation infrared-(2DCOS-IR) revealed ester group (uronic acid) as a major organic functional group that promoted Ce(III) removal. Excitation-emission matrix-(EEM) spectrum and 2DCOS-IR suggested the dominance of Fulvic acid, hypothesized to have promoted the performance of the PN process under Ce(III) dosage.

The results of modelling the effect of cell sizes on the microorganism disintegration process are presented. Experiments were conducted in a horizontal bead mill for baker's yeast Saccharomyces cerevisiae. The kinetics of the cell disruption process was investigated by optical image analysis and the release of intracellular protein by Bradford method. A large variation in the size of yeast from one production cycle has been demonstrated. A significant increase in the constant rate of the process with an increase in the range of the cell size class was demonstrated. More beneficial values of the coefficient of determination were obtained for the spherical model of the cell. Worse results of the process description were obtained for the ellipsoidal model. They may result from large variations in cell volume in individual size classes. The greatest changes in the cell Elongation parameter within one size class ranged from 1.00 to 1.54. Unlabelled Image • The theory of random transformation of dispersed matter were used for modelling. • Baker's yeast Saccharomyces cerevisiae has very different cell sizes and shapes. • The rate constant of yeast disintegration depends on the size of cells. • Process description results are better for a spherical cell model then ellipsoidal. • The resultant of linear component processes is a linear total process. [ABSTRACT FROM AUTHOR]

The anaerobic digestion (AD) of food waste (FW) has been recognised as a low-cost and high-efficiency alternative that mitigates the impacts of the final disposal of FW, while facilitating the production of high value-added by-products, such as biogas and digestate. In this study, the simultaneous incidence of two significant variables in the AD of FW were evaluated: the temperature (20, 35 and 55 °C), which affects the kinetics of the process, and the head space (20, 35 and 50%), which can affect the pH and therefore the biochemical methane potential (BMP). A composite central design was used, and response surface methodology (RSM) and kinetic models (the first-order and Gompertz models) were used to analyse the process. At higher temperatures and smaller head spaces, inhibition phenomena were reduced by the consumption of bicarbonate alkalinity and decreasing the pH, resulting in a higher process performance. The optimal conditions were a temperature of 48.9°C and a head space of 20%. The Gompertz kinetic model fit the process dynamics better and with a lower error than the first-order model.

The anaerobic digestion (AD) of food waste (FW) has been recognised as a low-cost and high-efficiency alternative that mitigates the impacts of the final disposal of FW, while facilitating the production of high value-added by-products, such as biogas and digestate. In this study, the simultaneous incidence of two significant variables in the AD of FW were evaluated: the temperature (20, 35 and 55 °C), which affects the kinetics of the process, and the head space (20, 35 and 50%), which can affect the pH and therefore the biochemical methane potential (BMP). A composite central design was used, and response surface methodology (RSM) and kinetic models (the first-order and Gompertz models) were used to analyse the process. At higher temperatures and smaller head spaces, inhibition phenomena were reduced by the consumption of bicarbonate alkalinity and decreasing the pH, resulting in a higher process performance. The optimal conditions were a temperature of 48.9°C and a head space of 20%. The Gompertz kinetic model fit the process dynamics better and with a lower error than the first-order model. [ABSTRACT FROM AUTHOR]

To explore the process kinetics of hydrogen evolution reaction (HER) on carbon-based Ni/NiO nanocomposite in the microbial electrolysis cells (MECs), the performance was systematically studied by different time-course sampling of five parallel single-chamber MECs operated under identical operating conditions, which included the electrochemical performance of anodes and cathodes, and the mechanism and kinetics of HER. It was hypothesized that the decreased performance of the nickel cathodes was due to corrosion and Ni dissolution. These results provide valuable insights into the effects of long-term operation on MEC performance. Image 1 • The time-course investigation into HER in a MEC. • The process kinetics of HER in a MEC. • Long-term HER shows correlation with characterisation variation of Ni/NiO. [ABSTRACT FROM AUTHOR]

Kinetic analysis of isobutylene synthesis from ethanol in the presence of a ZnO/ZrO2 catalyst synthesized by incipient wetness impregnation of zirconium hydroxide with zinc nitrate has been conducted. Analysis data have been used to determine primary, secondary, stable, and unstable products. The selectivity for the reaction products and the order of their formation have been determined. A general scheme of the reaction routes for ethanol conversion to isobutylene has been proposed. [ABSTRACT FROM AUTHOR]

• Transitory stage of photocatalytic degradation of ethylene was observed. • Non-volatile species of ethylene oxidation were observed. • Non-volatile by-products were assigned to furan and furfural oligomers (N < 10). • Theoretical model was proposed explaining the reaction kinetics. A complex kinetics of the photocatalytic decomposition of gaseous ethylene on nanoparticulate Fe(III) doped anatase TiO 2 was analyzed in a continuous-flow fixed-bed reactor. The analysis evidenced the production of non-volatile intermediate reaction products, which cover the photocatalyst surface and delay the time of attaining the stationary reactor performance. As a result, the reaction yield slowly increases during the long-lasted (∼3 h) intermediate stage. Based on Raman, FTIR and thermal post-treatment analyses, we assigned the major non-volatile reaction product to polymeric oxidized hydrocarbons: furan and furfural oligomers. A theoretical model is proposed explaining the observed kinetics. [ABSTRACT FROM AUTHOR]

Fixed-bed adsorption is widely applied for the purification of liquid mixtures, including industrial waste water. The adsorption purification of waste water from petroleum products and heavy metals with the use of peat is modeled. A process model taking the longitudinal stirring of the liquid-phase flow, the outer- and inner-diffusion resistance of flow in sorbent grains, and the phenomena of adsorption on the peat surface into account is constructed. The results of experimental studies are presented. The effect of the abnormal diffusion of heavy metal ions in peat has been revealed and explained. Based on these studies, the isotherm of petroleum product adsorption from waste water and the change in the mass transfer coefficient depending on the adsorption value were plotted. The effect of chemical kinetics on the ion-exchange rate has been experimentally determined. The experimental curves of the adsorption of heavy metal ions are processed using the equations of diffusion and chemical kinetics. Based on these results some conclusions have been made. [ABSTRACT FROM AUTHOR]

Katalityczne spalanie domieszek organicznych powietrza należy do podstawowych technologii oczyszczania gazów. Opisano makrokinetykę spalania domieszek na katalizatorach porowatych. Ujęcie teoretyczne jest zgodne ze standardowym opisem makrokinetyki procesów katalitycznych. Opisano relacje pomiędzy podstawowymi wielkościami: obserwowaną szybkością procesu r*, szybkością reakcji w obszarze kinetycznym r i współczynnikiem wykorzystania powierzchni η, w formie r*=r ·η. Łączy je moduł Thielego ö. Podano równanie kinetyczne dla warunków izotermicznych i warunków nieizotermicznych. Wpływ transportu masy i transportu ciepła w ziarnie katalizatora na przebieg procesu opisano za pomocą współczynnika wykorzystania powierzchni η. Podano równanie opisujące ten współczynnik dla warunków izotermicznych i nieizotermicznych

The article deals with the kinetics of the pressure growth in the headspace of the bottle filled by carbonated beverage after the rapid opening and closing of the output valve placed on the bottle neck. The rate of pressure growth was measured by an electronic pressure recorder with quick response. Escape of CO2 was also initiated by electrolysis or by inserting a porous material into beer. The pressure growth in the bottle can be described by a simple kinetic equation with two parameters, the initial rate of pressure growth and the constant describing the suppression of bubbles detachment from the surface of the solid particles. Continuous removal of CO2 microbubbles bound to the surface of solid material e.g. by permanent shaking is limited by the solubility of carbon dioxide and temperature. The new technique also allows estimate the effect of various substrates and brewing process parameters to cause gushing. It may also be used to search for bottles with a scuffed surface after filling them with carbonated water.

Abstract Hydrogen (H 2) is considered as fuel for future and its biological production from renewable feedstocks is very promising. Dark fermentation of fruit-vegetable waste (FVW) and cottage cheese whey (CCW) for the production of H 2 constitutes a promising way for combining energy generation and lignocellulosic waste management. In this work, process kinetics of biohydrogen production via dark fermentation of FVW and CCW by pretreated anaerobic sludge inocula were investigated. To inhibit H 2 consuming methanogens, the effects of various inoculum pretreatment, viz., 2-bromoethanesulfonate, heat-shock, acid, alkali, UV, and ultrasonication on H 2 -production were investigated which revealed 2-bromoethanesulfonate, heat-shock and acid-treated inoculum resulted in maximum bioH 2 production and yield of 118.12 ± 1.05, 93.37 ± 1.3, 96.32 mMol/L and 1.66, 1.22 ± 0.01, 1.39 ± 0.02 mMol/gCOD initial , respectively. The effects of system initial pH, substrate to inoculum (S 0 /X 0) and carbon to nitrogen (C/N) ratio on H 2 -production were evaluated which revealed maximum H 2 production and yield could be achieved at pH 7, S 0 /X 0 of 10.6 g COD /g VS , and C/N 26.8. Modified Gompertz model and Modified Logistic model were used to define various kinetic parameters pertaining to cumulative H 2 -production which showed high R 2 values (≥0.98). The influence of pH on H 2 and ethanol/volatile fatty acids production kinetics were evaluated using Andrew's and Ratkowsky's model showing relatively good R 2 values (≥0.62). Remarkably high production of ethanol (2.43 ± 0.28 mg/L) was noticed alongside H 2 production at pH 7 suggesting that bioethanol can be recovered at the end of fermentative H 2 production. Terminal Restriction Fragment Length Polymorphism and 16s rDNA sequencing revealed dominance of 9 bacterial species such as Escherichia coli , Clostridium butyricum , Streptococcus henryi , and 6 others uncultured bacteroides. This research determined different kinetic parameters for an enhanced H 2 production strategy by co-fermentation of FVW and CCW providing an understanding of process behavior which will in turn help in the upscaling of the H 2 -production processes. Graphical abstract Unlabelled Image Highlights • Various inoculum pretreatments were evaluated to maximize H 2 production. • Characterization of H 2 production from co-fermentation of fruit-vegetable waste and cheese whey. • Kinetic analyses of H 2 production using various unstructured mathematical models. • Microbial population analysis of consortium was conducted using t-RFLP and 16s rDNA sequencing. [ABSTRACT FROM AUTHOR]

Self-assembly of nanoscale materials represents the prevailing bottom-up strategy toward constructions of nanoarchitectures with hierarchical structures and desirable functionalities. Differentiated from the synthesis-then-assembly approach which involves organization of preformed uniform nanoparticles (NPs), the synthesis-cum-assembly , where the formation and the assembly of the primary NPs occur simultaneously within the same experimental settings is endowed with inherent advantages in building functional architectures of well-defined morphologies, hierarchical structures, controllable dimensions, permanent stability and excellent processability. Current methodologies to operate synthesis-cum-assembly could be broadly divided into three major categories: (i) the process involving solid particles as both precursors and templates, such as SiO 2 beads, coordination polymer colloidal particles, inorganic–organic supermolecules, metal/metal oxides; (ii) the one assisted with inertial templates such as micelles, vesicles and emulsions of various amphiphiles including surfactants, polymers and biomolecules; and (iii) the template-free case which is relatively less reported. Salient features of these methods were analyzed and compared by selecting typical studies, in order to demonstrate the working principles in each approach. This review puts emphasis upon strategies to balance the process kinetics between the chemical reactions of generating primary NPs and the physical assembly process; the various postsynthetic modifications and applications of 1D–3D endproducts gained from various synthesis-cum-assembly studies toward heterogeneous catalysis, adsorptions, electrocatalysis, lithium-ion batteries etc ., are also covered, and future research directions are present as well. [ABSTRACT FROM AUTHOR]

Lightweight and energy saving autoclaved aerated concrete (AAC) acting as a new building material were prepared by using magnetite tailings from iron ore as main raw materials, and the purpose of comprehensive utilization of tailings resources was to improve their utilization efficiency. The effects of curing system on AAC product performance were discussed. The autoclave curing reaction kinetics was studied as well as the generated amount of hydration product trends over autoclave curing temperature and time were analyzed. The results indicated that the properties of AAC was in accordance with Chinese national standard the A3.5B06 class of GB/T11968-2006 by prepared from magnetite tailing as the main raw materials. Meanwhile, autoclave curing process was controlled by the diffusion velocity through the products' layers of reactants, and the apparent activation energy of autoclave curing process was 19. 269 kj/mol. Compressive strength of aerated concrete is improved by mutual cementation between the appropriate amount of calcium silicate hydrate and tobermorite crystal. [ABSTRACT FROM AUTHOR]

Reactions of manganese oxides of various compositions with sulfuric acid solutions have been studied by kinetic and electrochemical methods. The surface composition of the manganese oxides has been shown to vary during the dissolution process. We present mathematical dependences of the dissolution rate on kinetic parameters of the electrolyte solution for the oxides of various compositions and interpret the behavior of the manganese oxide with various compositions during dissolution in sulfuric acid solutions of various concentrations. [ABSTRACT FROM AUTHOR]

Copyright of Ecological Engineering / Inżynieria Ekologiczna is the property of Polish Society of Ecological Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the last decade, many Activated Sludge Model No. 3 (ASM3) extensions were proposed to adopt new concepts such as simultaneous storage and growth of heterotrophic organisms and two-step nitrification-denitrification processes. From these ASM3 model extensions, four are included in this study: ASM3 with two-step nitrification-denitrification, ASM3 for simultaneous autotrophic and heterotrophic storage-growth, ASM3 extension for two-step nitrification-denitrification, and ASM3 for simultaneous storage-growth and nitrification-denitrification. The four models are analyzed and compared to the original ASM3 model with respect to the modeling concepts adopted, the process kinetic rates modified, and the kinetic parameters and stoichiometric coefficients introduced. A new schematic representation of the modeling concepts concerning the organisms' activities is introduced. A database of all parameters and coefficients of the four considered model extensions is developed using a unified notation system to reduce effort and confusion of the future researchers using their values as initial calibration or guidance values. Finally, the four models and the original ASM3 model are implemented using the parameters' values from the developed database, then the simulation results are compared with actual field measurements. [ABSTRACT FROM AUTHOR]