Procjena kinetičkih parametara i evaluacija modela za proces aerobne biokonverzije organske frakcije komunalnog krutog otpada

Aerobic bioconversion is very interesting process for the mathematical modelling and optimisation from the aspect of improving and accelerating the process, which is reflected in a higher organic matter decomposition rate. The aim of this research was to estimate the kinetic parameters in a dynamic model that described aerobic biodegradation of organic fraction of municipal solid waste (OFMSW) with various additions, from an engineering aspect. The presented mathematical model based on heat and mass transfer phenomena is a dynamic model for the gas-liquid-solid system. For the optimization and process simulation, three experiments were performed in three geometrically identical reactor systems at the same time, with different initial composition of composting mixtures. Data obtained experimentally from one reactor were used to optimize kinetic parameters of the model, and data from the other two reactors were used to verify and evaluate the dynamic model. Detailed statistical analysis showed narrow values of 95 % confidence interval for estimated parameters, indicating the appropriate accuracy of parameter estimation. Better data agreement was achieved in the reactor with a smaller ratio of OFMSW and additives, and the most accurately predicted dynamic state variable was the mass of organic matter. Parameter sensitivity analysis showed that the most sensitive parameters were reaction order n and activation energy E. Overall, the application of this model with optimised kinetic parameters of the aerobic biodegradation process represents a tool to predict the most important process variables (SD = 0.3378). This work is licensed under a Creative Commons Attribution 4.0 International License.Postupak aerobne biorazgradnje zanimljiv je za numerička istraživanja da bi se postigla bolja učinkovitost postupka, što se odražava u većoj brzini razgradnje organske tvari. Cilj ovog istraživanja bio je procijeniti kinetičke parametre u dinamičkom modelu koji opisuje proces aerobne biorazgradnje organske frakcije komunalnog krutog otpada s različitim dodatcima s inženjerskog aspekta. Predstavljeni matematički model zasnovan na pojavama prijenosa topline i mase dinamički je model sustava plin–tekućina–krutina. U svrhu optimizacije i simulacije postupka izveden je jedan pokus u tri reaktorska sustava sa smjesama različitog početnog sastava. Eksperimentalni podatci dobiveni iz jednog reaktora upotrijebljeni su za procjenu kinetičkih parametara modela, a podatci iz preostala dva reaktora upotrijebljeni su za provjeru i procjenu dinamičkog modela koji izvodi simulaciju. Detaljna statistička analiza pokazala je uske vrijednosti 95 %-tnog intervala pouzdanosti, što ukazuje na odgovarajuću točnost procjene parametara. Bolje slaganje podataka postignuto je u reaktoru s manjim udjelom dodataka, a najpreciznije predviđena varijabla je konverzija organske tvari. Analiza osjetljivosti parametara pokazala je da su najosjetljiviji red reakcije n i energija aktivacije E. Sveukupno, primjena ovog modela s procijenjenim kinetičkim parametrima u aerobnom procesu biorazgradnje pruža alat za predviđanje najvažnijih procesnih varijabli (SD = 0,3378). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Local and global sensitivity analysis of model parameters for composting process

In this paper, a local sensitivity analysis was performed using one at time technique (OAT) on the parameters of the mathematical model for the composting process. An integrated mathematical model for composting process was used, in which kinetic parameters and the reaction order was estimated. The values of the absolute and relative sensitivity of the specified parameters are calculated. The following dynamic variables were selected as the objectives functions for sensitivity analysis: the mass of organic matter at the end of the process, the minimum amount of oxygen, the maximum amount of carbon dioxide and the maximum substrate temperature. The sensitivity analysis showed that the variations of the parameters mostly affect the amount of carbon dioxide, and at least the substrate temperature, and that the most sensitive parameter is the reaction order. ANOVA analysis (one-way and two-way) showed a statistically significant difference between experimental data

Numerical simulation of soda ash drying process in pneumatic drying system with industrial scale

In this paper a mathematical model for the soda ash drying process in a pneumatic dryer was presented. The model presents a macroscopic aspect of the drying process, for a two-phase, gas-solid system. The model is based on mass and heat transfer between the gas phase and the particle, movement of air and particles through the system, and geometric characteristics of the drying system (fan, air heater, pneumatic dryer, and cyclone). The effects of the process parameters, such as airflow, inlet air temperature, and relative humidity, temperature at the inlet of the dryer, etc., have been studied by solving the model. Also, the model was tested for different values of the capacity of wet soda and different values of the operating parameters of the heating medium. The model was implemented in MATLAB and solved with a nonlinear equations solver. Data obtained by the model were compared with industrial pneumatic dryer data for drying wet soda ash particles with good agreement

Kinetic and equilibrium study of graphene and copper oxides modified nanocomposites for metal ions adsorption from binary metal aqueous solution

Presently, the main cause of pollution of natural water resources is heavy metal ions. The removal of metal ions such as nickel (Ni2+) and cadmium (Cd2+) has been given considerable attention due to their health and environmental risks. In this regard, for wastewater treatment containing heavy metal ions, graphene oxide (GO) nanocomposites with metal oxide nanoparticles (NPs) attained significant importance. In this study, graphene oxide stacked with copper oxide nanocomposites (GO/CuO-NCs) were synthesized and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscopy (AFM) analytical procedures. The prepared GO/CuO-NCs were applied for the removal of Ni2+ and Cd2+ ions from a binary metal ion system in batch and continuous experiments. The obtained results revealed that GO/CuO-NCs exhibited the highest removal efficiencies of Ni2+ (89.60% ± 2.12%) and Cd2+ (97.10% ± 1.91%) at the optimum values of pH: 8, dose: 0.25 g, contact time: 60 min, and at 50 ppm initial metal ion concentration in a batch study. However, 4 mL/min flow rate, 50 ppm initial concentration, and 2 cm bed height were proved to be the suitable conditions for metal ion adsorption in the column study. The kinetic adsorption data exhibited the best fitting with the pseudo-second-order model. The adsorption isotherm provided the best-fitting data in the Langmuir isotherm model. This study suggested that the GO/CuO nanocomposites have proved to be efficient adsorbents for Ni2+ and Cd2+ ions from a binary metal system

Separation of Fumaric and Maleic Acid Crystals from the Industrial Wastewater of Maleic Anhydride Production

In this research, a physicochemical analysis of the industrial wastewater from a factory that produces maleic anhydride was performed. Based on the conducted analysis (pH, electrical conductivity, density of the liquid phase, boiling point of the waste suspension, chemical as well as biological oxygen demand, and dry matter), it can be concluded that the waste stream obtained at the outlet pipe from the plant resulting from the production of maleic anhydride requires appropriate treatments. Some of the parameters measured, e.g. pH (0.97±0.06), boiling point (106.8±1.3°C) and acidity, indicate the presence of organic acids such as fumaric and maleic acids, which are formed during the production of maleic anhydride. The possibility of extracting crystals by adding urea and thiourea followed by forced cooling in a heat exchanger was investigated. The most effective method was the addition of thiourea when the most significant amount of crystals was obtained, namely 17.29 wt%. The addition of thiourea in combination with forced cooling greatly facilitates the process of separating the solid and liquid phases of the waste suspension, which could later be adequately treated by physical, chemical or biological methods