scholarly journals Performance evaluation and substrate removal kinetics in a thermophilic anaerobic moving bed biofilm reactor for starch degradation

2021 ◽  
Author(s):  
H. M. A. Shahzad ◽  
S. J. Khan ◽  
Z. Habib
Keyword(s):  
Second Order ◽  
Biofilm Reactor ◽  
Starch Degradation ◽  
Yield Coefficient ◽  
Moving Bed Biofilm Reactor ◽  
Order Model ◽  
Moving Bed ◽  
First Order ◽  
Substrate Removal ◽  
Second Order Model

Abstract A laboratory-scale anaerobic moving bed biofilm reactor (AnMBBR) was installed and operated at various hydraulic retention times (HRTs) of 20 to 1.5 d with surface area loading rate (SALR) of 0.86 to 11.43 gCOD/m2/d. Synthetic starch containing desizing wastewater with chemical oxygen demand (COD) of 12.75 g/L was prepared and fed into the reactor. Monod, modified Stover-Kincannon, Grau second-order and First-order substrate removal models were used to evaluate the results of AnMBBR. COD removal efficiency of bioreactor was dwindled by increasing the SALR or reducing the HRT. Decay coefficient (Kd) and yield coefficient (Y) for Monod model were 0.027 1/d and 1.01 mgVSS/mgCOD, respectively. Maximum substrate utilization rate (Umax) and kinetic constant (Kb) for Modified Stover-Kincannon model were estimated as 12.57 and 15.22 g/L/d, respectively. The constants (a and b) for Grau second-order model were found to be 1.09 and 1.31 whilst kinetic coefficient for Second-order model and First-order substrate removal model were 1.62 and 1.55 1/d, respectively. Modified Stover-Kincannon model and Grau second-order model were found to be the best fit for experimental data with R2 value of 0.99. The findings suggest that these models can be applied to predict the behaviour of AnMBBR on various scales.

Second-Order Correlation of Klinkenberg-Corrected Permeability and its Experimental Verification on Heterogeneously-Stressed Gas Shale

2020 ◽  
Author(s):  
Yufei Chen ◽  
Changbao Jiang ◽  
Juliana Y. Leung ◽  
Andrew K. Wojtanowicz ◽  
Dongming Zhang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Second Order ◽  
Gas Shale ◽  
Order Model ◽  
First Order ◽  
Gas Slippage ◽  
Steady State Method ◽  
Slippage Effect ◽  
Stress Heterogeneity ◽  
Second Order Model

Abstract Shale is an extremely tight and fine-grained sedimentary rock with nanometer-scale pore sizes. The nanopore structure within a shale system contributes not only to the low to ultra-low permeability coefficients (10−18 to 10−22 m2), but also to the significant gas slippage effect. The Klinkenberg equation, a first-order correlation, offers a satisfying solution to describe this particular phenomenon for decades. However, in recent years, several scholars and engineers have found that the linear relation from the Klinkenberg equation is invalid for most gas shale reservoirs, and a need for a second-order model is, therefore, proceeding apace. In this regard, the purpose of this study was to develop a second-order approach with experimental verifications. The study involved a derivation of a second-order correlation of the Klinkenberg-corrected permeability, followed by experimental verifications on a cubic shale sample sourced from the Sichuan Basin in southwestern China. We utilized a newly developed multi-functional true triaxial geophysical (TTG) apparatus to carry out permeability measurements with the steady-state method in the presence of heterogeneous stresses. Also discussed were the effects of two gas slippage factors, Klinkenberg-corrected permeability, and heterogeneous stress. Finally, based on the second-order slip theory, we analyzed the deviation of permeability from Darcy flux. The results showed that the apparent permeability increased more rapidly as the pore pressure declined when the pore pressures are relatively low, which is a strong evidence of the gas slippage effect. The second-order model could reasonably match the experimental data, resulting in a lower Klinkenberg-corrected permeability compared with that from the linear Klinkenberg equation. That is, the second-order approach improves the intrinsic permeability estimation of gas shales with the result being closer to the liquid permeability compared with the Klinkenberg approach. Analysis of the experimental data reported that both the first-order slippage factor A and the second-order slippage factor B increased with increasing stress heterogeneity, and that A was likely to be more sensitive to stress heterogeneity compared with B. Interestingly, both A and B first slightly increased and then significantly as the permeability declined. It is recommended that when the shale permeability is below 10−18 m2, the second-order approach should be taken into account. Darcy’s law starts to deviate when Kn > 0.01 and is invalid at high Knudsen numbers. The second-order approach seems to alleviate the problem of overestimation compared with the Klinkenberg approach and is more accurate in permeability evolution.

Effectiveness of parallel second order model over second and first order models

2011 ◽  
Vol 32 (1-3) ◽  
pp. 107-114 ◽  
Author(s):  
Ahmad Jabari Kohpaei ◽  
Arumugam Sathasivan ◽  
Hanieh Aboutalebi
Keyword(s):  
Second Order ◽  
Order Model ◽  
First Order ◽  
Second Order Model

scholarly journals Analytical Deriving of Second Order Model of Payne from First Order Lighthil-Whitham-Richards Model

2013 ◽  
Vol 13 (4) ◽  
pp. 54-62
Author(s):  
Vasilka Stoilova ◽  
Emil Nikolov ◽  
Nina Nikolova
Keyword(s):  
Second Order ◽  
Order Model ◽  
First Order ◽  
Richards Model ◽  
Payne Model ◽  
Second Order Model

Abstract Analytical deriving has been realized to obtain the second order Payne model from the first order Lighthil-Witham-Richards model.

Kinetics and Equilibrium Study for Acetazolamide in Soils

2013 ◽  
Vol 781-784 ◽  
pp. 2296-2300
Author(s):  
Jian Qiu Chen ◽  
Zhi Liang Wang ◽  
Guo Ping Li ◽  
Rui Xin Guo ◽  
Yu Zhu Hu
Keyword(s):  
Clay Content ◽  
Second Order ◽  
Sorption Behavior ◽  
Order Model ◽  
Sorption Data ◽  
First Order ◽  
Kd Values ◽  
Pseudo Second Order ◽  
Pseudo First Order ◽  
Second Order Model

Sorption of Acetazolamide was found to be impacted by clay content and soil solution pH, with higher Kd values for soils with higher clay content and higher Kd values as the pH increased. Sorption data on soils were well fitted with Freundlich model (R2> 0.98). The kinetics of adsorption of Acetazolamide has been discussed using four kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, the Elovich equation, the intraparticle diffusion model. The pseudo-first-order model and the pseudo-second-order model were both used to describe the kinetics data, and the pseudo-second-order model could describe the sorption behavior of Acetazolamide well.

scholarly journals Kinetics of Organic Biodegradation and Biogas Production in the Pilot-Scale Moving Bed Biofilm Reactor (MBBR) for Piggery Wastewater Treatment

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Thi Ha Nguyen ◽  
Manh Khai Nguyen ◽  
Thi Hoang Oanh Le ◽  
Thanh Tu Bui ◽  
Trong Hieu Nguyen ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Biogas Production ◽  
Pilot Scale ◽  
Second Order ◽  
Biofilm Reactor ◽  
Monod Model ◽  
Moving Bed Biofilm Reactor ◽  
Piggery Wastewater ◽  
Moving Bed ◽  
Kinetics Of

In this research, the kinetics of COD biodegradation and biogas production in a moving bed biofilm reactor (MBBR) at pilot scale (10 m3) for piggery wastewater treatment were investigated. Polyethylene (PE) was used as a carrying material, with organic loading rates (OLRs) of 10, 15, and 18 kgCOD/m3 day in accordance to hydraulic retention times (HRTs) of 0.56, 0.37, and 0.3 day. The results showed that a high COD removal efficiency was obtained in the range of 68–78% with the influent COD of 5.2–5.8 g/L at all 3 HRTs. About COD degradation kinetics, in comparison to the first- and second-order kinetics and the Monod model, Stover–Kincannon model showed the best fit with R2 0.98 and a saturation value constant (KB) and a maximum utilization rate (Umax) of 52.40 g/L day and 82.65 g/L day, respectively. The first- and second-order kinetics with all 3 HRTs and Monod model with the HRT of 0.56 day also obtained high R2 values. Therefore, these kinetics and models can be further considered to be used for predicting the kinetic characteristics of the MBBR system in piggery wastewater treatment process. The result of a 6-month operation of the MBBR was that biogas production was mostly in the operating period of days 17 to 80, around 0.2 to 0.3 and 0.15–0.20 L/gCODconverted, respectively, and then reduction at an OLR of 18 kgCOD/m3. After the start-up stage, day 35 biogas cumulative volume fluctuated from 20 to 30 m3/day and reached approximately 3500 m3 for 178 days during the whole digestive process. Methane is accounted for about 65–70% of biogas with concentration around 400 mg/L.

scholarly journals Overshoot of D-dot sensor in measurement of electric field

2021 ◽  
Vol 2083 (2) ◽  
pp. 022033
Author(s):  
Jinghai Guo ◽  
Liang Ma ◽  
Yinhui Cheng ◽  
Xutong Wang ◽  
Yifei Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Equivalent Circuit ◽  
Field Measurement ◽  
Equivalent Circuit Model ◽  
Second Order ◽  
Order Model ◽  
Scanning Method ◽  
First Order ◽  
The Given ◽  
Second Order Model

Abstract This paper analyzes the cause of the overshot of the signal measured by D-dot sensor, and points out that the second-order RLC equivalent circuit model can explain the overshot Taking the asymptotic conical antenna as an example, the inductance L of the second-order model is obtained by using CST simulation and Pspice parameter scanning method. The first-order model and the second-order model are used to calculate the electric field waveform. Under the given conditions, the first-order model is used to obtain the electric field waveform, the waveform overshot is serious, the maximum overshoot reaches 27%, while the second-order model is used to improve the ringing phenomenon, And the maximum overshoot is reduced to 5%.The results show that the second-order model is more accurate than the first-order model and can improve the precision of electric field measurement using D-dot sensor.

Isothermal Microtube Heat Transfer With Second-Order Slip Flow and Temperature Jump Boundary Conditions

2006 ◽  
Author(s):  
Nian Xiao ◽  
John Elsnab ◽  
Susan Thomas ◽  
Tim Ameel
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Nusselt Number ◽  
Boundary Conditions ◽  
Temperature Jump ◽  
Slip Flow ◽  
Second Order ◽  
Order Model ◽  
First Order ◽  
Second Order Model

Two analytical models are presented in which the continuum momentum and energy equations, coupled with second-order slip flow and temperature jump boundary conditions, are solved. An isothermal boundary condition is applied to a microchannel with a circular cross section. The flow is assumed to be hydrodynamically fully developed and thermal field is either fully developed or thermally developing from the tube entrance. A traditional first-order slip boundary condition is found to over predict the slip velocity compared to the second-order model. Heat transfer increases at the upper limit of the slip regime for the second-order model. The maximum second-order correction to the first-order Nusselt number is on the order of 18% for air. The second-order effect is also more significant in the entrance region of the tube. The Nusselt number decreases relative to the no-slip value when slip and temperature jump effects are of the same order or when temperature jump effects dominate. When temperature jump effects are small, the Nusselt number increases relative to the no-slip value. Comparisons to a previously reported model for an isoflux boundary condition indicate that the Nusselt number for the isoflux boundary condition exceeds that for the isothermal case at all axial locations.

Adsorption of Phthalate Esters (PAEs) from Aqueous Solution onto Activated Carbons from Softstem Bulrush

2010 ◽  
Vol 152-153 ◽  
pp. 791-796
Author(s):  
Hui Jun Xie ◽  
Qiang Ma ◽  
Wei Tan ◽  
Jian Zhang
Keyword(s):  
Aqueous Solution ◽  
Activated Carbons ◽  
Phthalate Esters ◽  
Freundlich Isotherm ◽  
Second Order ◽  
Order Model ◽  
First Order ◽  
Effects Of Ph ◽  
Pseudo Second Order ◽  
Second Order Model

Removal of Phthalate Easters (PAEs) by softstem bulrush carbon (SBC) in aqueous solution was studied. In this work, the effects of pH, adsorbent dosage (0.8-2.8g), and initial DMP concentration (20-100 mg/L) on the adsorption system were investigated. It turned out that the effective pH was 7.0 and the optimum adsorbent dose was 2.0 g/L. Equilibrium experimental data at 283, 293 and 308 K were better represented by Freundlich isotherm than Langmuir isotherm. In addition, adsorption kinetics was determined using pseudo-first-order model, pseudo-second-order model. The results indicated that the adsorption of DMP onto SBC followed pseudo-second-order model.

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