scholarly journals Mathematical modeling of primary sludge anaerobic hydrolysis

2019 ◽  
Keyword(s):  
Kinetic Parameters ◽  
Model Calibration ◽  
Production Model ◽  
Model Parameters ◽  
Specific Rate ◽  
Primary Sludge ◽  
Production Processes ◽  
Aceticlastic Methanogenesis ◽  
Different Temperatures ◽  
Calibration And Verification

<p>The aim of this work was the application and evaluation of a mathematical model for the simulation of anaerobic hydrolysis and acid production processes. For the description of the processes involved, the Anaerobic Digestion Model ADM1 was employed. The ADM1 implementation in prefermenters is relatively easy, but the estimation of its components concentrations, kinetic parameters and stoichiometric coefficients, remains a problem to be solved. This study provides useful results for the ADM1 implementation in acid digesters design and operation. Model calibration and verification was performed using experimental data from two bench scale acid digesters operating at different temperatures (12, 20, 27 and 34 °C) and retention times (1,2, 4 and 6 days). Model sensitivity analysis illustrated that the values of pH, disintegration kinetic parameter and aceticlastic methanogenesis specific rate, as well as biomass and inert soluble COD concentrations in the primary sludge exert a significant influence on soluble COD production. Model parameters (disintegration and hydrolysis kinetic parameters and specific rate of methane production) as well as the temperature dependency of these parameters are given in this paper.</p>

Sewer flow quality modelling

1997 ◽  
Vol 36 (5) ◽  
pp. 177-184
Author(s):  
Lennart Heip ◽  
Johan Van Assel ◽  
Patrick Swartenbroekx
Keyword(s):  
Model Calibration ◽  
Model Building ◽  
Quality Model ◽  
Hydraulic Behaviour ◽  
Measuring Campaign ◽  
Flow Quality ◽  
Wet Weather ◽  
Calibration And Verification ◽  
Set Up ◽  
Dry Weather Flow

Within the framework of an EC-funded SPRINT-project, a sewer flow quality model of a typical rural Flemish catchment was set up. The applicability of such a model is demonstrated. Furthermore a methodology for model building, data collection and model calibration and verification is proposed. To this end an intensive 9 month measuring campaign was undertaken. The hydraulic behaviour of the sewer network was continuously monitored during those 9 months. During both dry weather flow (DWF) and wet weather flow (WWF) a number of sewage samples were taken and analysed for BOD, COD, TKN, TP and TSS. This resulted in 286 WWF and 269 DWF samples. The model was calibrated and verified with these data. Finally a software independent methodology for interpretation of the model results is proposed.

scholarly journals Exergy efficiency of thermochemical syngas-to-ethanol production plants

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Marcos Paulo Gabriel da Costa e Silva ◽  
Júlio Cesar de Carvalho Miranda
Keyword(s):  
Ethanol Production ◽  
Process Improvement ◽  
Second Generation ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Exothermic Reactions ◽  
Production Processes ◽  
Different Temperatures ◽  
Exergy Analyses ◽  
Second Generation Ethanol

Abstract This work presents exergy analyses applied in four different conceptual second-generation ethanol production processes through a thermochemical route using catalysts based on Molybdenum (P-1), Copper (P-2), and Rhodium (P-3 and P-4), aiming to assess their exergetic efficiencies. The results show that the conceptual processes have satisfactory exergy efficiencies in both cases, when compared among themselves and when compared with other processes reported in literature. The processes’ efficiency for P-1, P-2, P-3 and P-4 were, respectively, 52.4%, 41.4%, 43.7% and 48.9%. The reactors were the sections in which exergy destruction was more significant, due to the exothermic reactions and mixing points (where streams with different temperatures were mixed). Such results show the potential of thermochemical ethanol production, besides opening the possibilities of process improvement. Graphic abstract

scholarly journals Optimal Calibration of Evaporation Models against Penman–Monteith Equation

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1484
Author(s):  
Dagmar Dlouhá ◽  
Viktor Dubovský ◽  
Lukáš Pospíšil
Keyword(s):  
Model Calibration ◽  
Heat Storage ◽  
Free Water ◽  
Complex Model ◽  
Model Parameters ◽  
Net Radiation ◽  
Statistical Measures ◽  
Pit Lakes ◽  
Evaporation Models ◽  
Monteith Equation

We present an approach for the calibration of simplified evaporation model parameters based on the optimization of parameters against the most complex model for evaporation estimation, i.e., the Penman–Monteith equation. This model computes the evaporation from several input quantities, such as air temperature, wind speed, heat storage, net radiation etc. However, sometimes all these values are not available, therefore we must use simplified models. Our interest in free water surface evaporation is given by the need for ongoing hydric reclamation of the former Ležáky–Most quarry, i.e., the ongoing restoration of the land that has been mined to a natural and economically usable state. For emerging pit lakes, the prediction of evaporation and the level of water plays a crucial role. We examine the methodology on several popular models and standard statistical measures. The presented approach can be applied in a general model calibration process subject to any theoretical or measured evaporation.

Parameters Identification of Johnson-Cook Constitutive Equation for Aluminum Brass

2014 ◽  
Vol 887-888 ◽  
pp. 1032-1035 ◽  
Author(s):  
Chang Chun Di ◽  
Kai Bo Cui ◽  
Jun Qi Qin ◽  
Da Lin Wu
Keyword(s):  
Testing Machine ◽  
Strain Curve ◽  
High Strength ◽  
Dynamic Mechanical Properties ◽  
Model Parameters ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Method Of Least Squares ◽  
Different Temperatures ◽  
Split Hopkinson

Aluminum brass HAL66-6-3-2 is abrasion-resistant alloy with high strength, hardness and wear resistance, corrosion resistance is also well, commonly used in the field of marine and ordnance industry. The quasi static and dynamic mechanical properties were tested through the use of electronic universal testing machine and Split Hopkinson Tension Bar (SHTB). Meanwhile, the material stress-strain curve at different temperatures and different strain rates is also obtained. Based on Johnson-Cook constitutive model, using the method of least squares fitting the experimental data to determine the model parameters, fitting and experimental results agree well.

STORAGE TEMPERATURE AS A FACTOR OF FAT MIGRATION IN GLAZED SUGARY CONFECTIONERY PRODUCTS

1970 ◽  
pp. 78-80
Author(s):  
N. B. Kondratyev ◽  
Е. V. Kazantsev ◽  
O. S. Rudenko ◽  
N. А. Petrova ◽  
I. А. Belova
Keyword(s):  
Fatty Acids ◽  
Migration Rate ◽  
Unsaturated Fatty Acids ◽  
Storage Temperature ◽  
Polymorphic Form ◽  
Specific Rate ◽  
Confectionery Products ◽  
Different Temperatures ◽  
Physical And Chemical Quality ◽  
Physical And Chemical

The fat migration processes by changing the fatty acid composition of individual parts of glazed sweets with praline-type bodies (based on peanuts) during storage at different temperatures was studied. The main mechanism of mass transfer is considered to be the fat migration through the volume of products through the capillaries. The maximum migration rate of the liquid fat phase is at a storage temperature of 23-25 ° C in samples without transisomers of unsaturated fatty acids. Its reduction is possible with the introduction of 20-30% lauric acid into the fat fraction of products. The crystalline structure of the confectionery fats included in the candy fillings has a significant effect on the migration rate of the liquid fat phase into the glaze. The smallest one corresponded to fats in the β-polymorphic form with an admixture of no more than 3% crystals in the β'-polymorphic form. The specific rate of fat migration has been calculated taking into account the size of a glazed sweets model samples. When in storage temperature increases from 18 to 27 ˚С, it increased 1.7 times. The results of studies of changes in the composition of fatty acids of model samples individual parts of glazed sweets during storage at temperatures of 18 and 27 °C are presented. The proposed approach makes it possible to predict the fat migration processes rate. The comprehensive assessment methodology, which includes the determination of physical and chemical quality indicators during storage, the regularities of fat migration and microbiological changes, will justify the requirements for the technology parameters and the recipe composition of glazed sugary confectionery products with a given expiration date.

Model Calibration for the High-Purity Oxygen Activated Sludge Process – Algorithm Development and Evaluation

1993 ◽  
Vol 28 (11-12) ◽  
pp. 163-171 ◽  
Author(s):  
Weibo (Weber) Yuan ◽  
David Okrent ◽  
Michael K. Stenstrom
Keyword(s):  
Activated Sludge ◽  
High Purity ◽  
Model Calibration ◽  
Process Model ◽  
Model Parameters ◽  
Complex Method ◽  
Activated Sludge Process ◽  
Activated Sludge Model ◽  
Kinetic Coefficients ◽  
Calibration Algorithm

A model calibration algorithm is developed for the high-purity oxygen activated sludge process (HPO-ASP). The algorithm is evaluated under different conditions to determine the effect of the following factors on the performance of the algorithm: data quality, number of observations, and number of parameters to be estimated. The process model used in this investigation is the first HPO-ASP model based upon the IAWQ (formerly IAWPRC) Activated Sludge Model No. 1. The objective function is formulated as a relative least-squares function and the non-linear, constrained minimization problem is solved by the Complex method. The stoichiometric and kinetic coefficients of the IAWQ activated sludge model are the parameters focused on in this investigation. Observations used are generated numerically but are made close to the observations from a full-scale high-purity oxygen treatment plant. The calibration algorithm is capable of correctly estimating model parameters even if the observations are severely noise-corrupted. The accuracy of estimation deteriorates gradually with the increase of observation errors. The accuracy of calibration improves when the number of observations (n) increases, but the improvement becomes insignificant when n&gt;96. It is also found that there exists an optimal number of parameters that can be rigorously estimated from a given set of information/data. A sensitivity analysis is conducted to determine what parameters to estimate and to evaluate the potential benefits resulted from collecting additional measurements.

scholarly journals SOLVATION OF THE [Cr(NCS)4(IMIDAZOLE)2] ION IN ETHANOL-WATER MIXTURES

2002 ◽  
Vol 10 (11) ◽  
pp. 63-72
Author(s):  
lon Ganescu ◽  
George Bratulescu ◽  
Ion Papa ◽  
Anca Ganescu ◽  
Alin Barbu ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Order Reaction ◽  
Water Molecules ◽  
Hydrogen Ions ◽  
Second Order Reaction ◽  
Acidic Solutions ◽  
The Third ◽  
Competitive Reactions ◽  
Different Temperatures ◽  
Kinetics Of

Salvation kinetics of [Cr(NCS)4(imidazole)2]- has been studied in ethanol-water mixtures at different temperatures. The first stage of the solvation consists of two competitive reactions: two NCS- ions are exchanged, presumably, by water molecules and simultaneously an imidazole molecule by ethanol, the latter in a second-order reaction, accelerated by hydrogen ions. The exchange of the amine is followed by the substitution of the first two NCS- ions. The third and fourth NCS- ions are substituted only in neutral and slightly acidic solutions. Kinetic parameters have been determined for reactions (1), (2), and (4). The influence of the solvent composition and acidity is discussed

scholarly journals Population changes in rattail species on the Chatham Rise

2021 ◽  
Author(s):  
◽  
Kathleen Large
Keyword(s):  
Maximum Likelihood ◽  
Stock Assessment ◽  
Production Model ◽  
Likelihood Method ◽  
Model Parameters ◽  
Important Species ◽  
Surplus Production ◽  
Surplus Production Model ◽  
Abundance Indices ◽  
The Impact

<p>The aim of this project was to conduct a stock assessment to determine the population dynamic characteristics of rattail species taken as bycatch in the hoki, hake and ling fishery on the Chatham Rise. No quantitative assessment of the current size of rattail populations , and how these may have changed over time, has been carried out before. There is interest in the need to quantify the impact of commercial fishing on the rattail populations, as rattails (Macrouridae family) are considered to be an ecologically important species complex in the deep ocean, and there may be the potential for the development of a commercial fishery based on their value as processed fishmeal. The minimum data required for a stock assessment are an abundance index and a catch history. Abundance indices are available for over 20 species of rattail produced from scientific surveys conducted annually on the Chatham Rise since 1992. Catch histories for individual rattail species in the same area are not available. A method was developed to reconstruct commercial catches of rattails from commercial effort data and survey catch and effort data. A surplus production model was fitted to the reconstructed catch data and survey abundance indices, using maximum likelihood and Bayesian methods to estimate model parameters and uncertainty. A surplus production model has two components: an observation model for abundance indices and a process model for population dynamics. Maximum likelihood estimation was applied to a model that specified errors for the observations only, and this produced estimates that had wide confidence intervals. A Bayesian approach was then taken to fit a statespace version of the model that incorporates errors associated with the observation and process models. While the Bayesian method produced more plausible parameter estimates (in comparison to the maximum likelihood method) and parameter uncertainty was reduced, our analysis indicated the posterior estimates were highly sensitive to the specification of different priors. There may be several reasons for these results, including: the small number of observations, lack of contrast in the data and mis-specification of the model. Meaningful estimates of the absolute size of rattail populations are not possible with these results, where estimates can vary by orders of magnitude depending on prior specification. This implies that more work needs to be done to develop more effective methods that can be used to help inform decisions regarding the management of these fish populations. Improving data collection, investigating informative priors and extending/respecifying the model are considered worthwhile avenues of future work to improve stock assessments of rattails.</p>

scholarly journals An Assessment Of Microalgal Biodiesel With Acetone, Butanol and Ethanol Using LIfe Cycle Assessment (LCA) Methodology

2021 ◽  
Author(s):  
Cherilyn Dignan
Keyword(s):  
Fossil Fuels ◽  
Ghg Emissions ◽  
Primary Energy ◽  
Biofuel Production ◽  
Production Model ◽  
Lca Methodology ◽  
Fuel Production ◽  
Renewable Fuel ◽  
Production Processes ◽  
Microalgal Biodiesel

Canada, as one of the largest producers and consumers of fossil fuels per capita on the planet, is attempting to reduce greenhouse gas (GHG) emissions. In order to accomplish this, fuel alternatives, such as biofuel, are required. Accordingly, this study uses LCA methodology to quantify the GHG impact of a unique biofuel production model. This unique model produces biodiesel (BD), acetone, butanol and ethanol (ABE) from microalgae and assesses the process GHG impact against other microalgal BD production processes. This study’s microalgal BD and ABE production process produces 76 kgCO2e per functional unit, whereas other comparable microalgal BD production processes produce between 3.7 and 85 kgCO2e. Overall, this study clarifies that without the development of versatile infrastructure to accommodate biofuel production, LCA studies will continue to find renewable fuel production processes net GHG positive for the simple reason that fossil resources are still the primary energy source.

scholarly journals Photosynthesis-irradiance parameters of marine phytoplankton: synthesis of a global data set

2017 ◽  
Author(s):  
Heather A. Bouman ◽  
Trevor Platt ◽  
Martina Doblin ◽  
Francisco G. Figueiras ◽  
Kristinn Gudmudsson ◽  
...  
Keyword(s):  
Primary Production ◽  
Broad Band ◽  
Marine Phytoplankton ◽  
Production Model ◽  
Initial Slope ◽  
Model Parameters ◽  
Data Set ◽  
Spatial Coverage ◽  
Basin Scale ◽  
Marine Primary Production

Abstract. The photosynthetic performance of marine phytoplankton varies in response to a variety of factors, environmental and taxonomic. One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis-irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data. The MAPPS P-E Database, which consists of over 5000 P-E experiments, provides information on the spatio-temporal variability in the two P-E parameters (the assimilation number, PmB, and the initial slope, αB, where the superscripts B indicate normalisation to concentration of chlorophyll) that are fundamental inputs for models (satellite-based and otherwise) of marine primary production that use chlorophyll as the state variable. Quality-control measures consisted of removing samples with abnormally-high parameter values and flags were added to denote whether the spectral quality of the incubator lamp was used to calculate a broad-band value of αB. The MAPPS database provides a photophysiological dataset that is unprecedented in number of observations and in spatial coverage. The database would be useful to a variety of research communities, including marine ecologists, biogeochemical modellers, remote-sensing scientists and algal physiologists. The compiled data are available at https://doi.org/10.1594/PANGAEA.874087 (Bouman et al., 2017).

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