Optimization of Sand-Bentonite Mixture for the Stable Engineered Barriers using Desirability Optimization Methodology: A Macro-Micro-Evaluation

Khalid Farooq,Zia ur Rehman,Muqadas Shahzadi,Hassan Mujtaba,Usama Khalid 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

In this paper, Desirability Optimization Methodology (DOM) is employed to achieve optimum sand bentonite mixture (SBM) based on multiple antagonist macro-geotechnical responses of the compacted SBM prepared using poorly graded sand with the mean grain size around 0.2 mm and bentonite with plasticity index around 157% for the stable engineered barriers (EBs). For this purpose, varying mix designs of SBM compacted at compaction energy of 2,700 kN-m/m3 are initially tested to determine their mechanical properties, volumetric-change behavior, and hydraulic conductivity. The unconfined compressive strength, cohesion, angle of internal fiction, swell pressure, compression index, and hydraulic conductivity are taken as the geotechnical design parameters for the SBM. Mathematical models are developed and statistically validated for these design parameters using sand content (SC) and bentonite content (BC) as the predictors. In addition, models are also developed to predict compression curves for compacted SBMs. Moreover, microstructural evaluation is conducted through scanning electron microscope (SEM) analysis to determine the SBM having a desirable microstructure for stable EB. It is observed that a major shift in the microstructure from medium pores to micro-pores occurs for the BC between 20% and 30%. Afterward, optimization of SBM is carried out by integrating developed models for the geotechnical design parameters in a desirability function (D) algorithm, which is subsequently simulated by setting maximization of strength and minimization of swell pressure, compressibility and hydraulic conductivity of compacted SBM as the goals. A reasonably high D-value is achieved for the SBMs having SC:BC in a range of 74:26 to 78:22 with the highest at 75.63:24.37 against the set goals. This study manifests an effective and pragmatic strategy for designing the SBM for a stable EB considering its antagonist hydraulic, volumetric change, and mechanical responses.

Study of an improved and novel venturi scrubber configuration for removal of radioactive gases from NPP containment air during severe accident

Farooq Mujahid,Ahmed Ammar,Qureshi Kamran,Shah Ajmal,Waheed Khalid,Siddique Waseem,Irfan Naseem,Ahmad Masroor,Farooq Amjad 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.9

Owing to the rising concerns about the safety of nuclear power plants (NPP), it is essential to study the venturi scrubber in detail, which is a key component of the filtered containment venting system (FCVS). FCVS alleviates the pressurein containment byfiltering and venting out the contaminated air. Themain objective of this research was to perform a CFD investigation of different configurations of a circular, non-submerged, selfpriming venturi scrubber to estimate and improve the performance in the removal of elemental iodine from the air. For benchmarking, a mass transfer model which is based on two-film theory was selected and validated by experimental data where an alkaline solution was considered as the scrubbing solution. This mass transfer model was modified and implemented on a unique formation of two self-priming venturi scrubbers in series. Euler-Euler method was used for two-phase modeling and the realizable K ε model was used for capturing the turbulence. The obtained results showed a remarkable improvement in the removal of radioactive iodine from the air using a series combination of venturi scrubbers. The removal efficiency was improved at every single data point.

Experimental investigation of aerosols removal efficiency through self-priming venturi scrubber

Suhail Ali,Khalid Waheed,Kamran Qureshi,Naseem Irfan,Masroor Ahmed,Waseem Siddique,Amjad Farooq 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10

Self-priming venturi scrubber is one of the most effective devices used to collect aerosols and soluble gas pollutants from gaseous stream during severe accident in a nuclear power plant. The present study focuses on investigation of dust particle removal efficiency of the venturi scrubber both experimentally and theoretically. Venturi scrubber captures the dust particles in tiny water droplets flowing into it. Inertial impaction is the main mechanism of particles collection in venturi scrubber. The water injected into venturi throat is in the form of jets through multiple holes present at venturi throat. In this study, aerosols removal efficiency of self-priming venturi scrubber was experimentally measured for different operating conditions. Alumina (Al2O3) particles with 0.4-μm diameter and 3950 kg/m3 density were treated as aerosols. Removal efficiency was calculated for different gas flow rates i.e. 3-6 m3/h and liquid flow rates i.e. 0.009–0.025 m3/h. Experimental results depict that aerosols removal efficiency increases with the increase in throat velocity and liquid head. While at lower air flow rate of 3 m3/h, removal efficiency decreases with the increase in liquid head. A theoretical model of venturi scrubber was also employed and experimental results were compared with mathematical model. Experimental results are found to be in good agreement with theoretical results.

Evaluation of Relative Density and Friction Angle Based on SPT-N Values

Hassan Mujtaba,Khalid Farooq,Nagaratnam Sivakugan,Braja M. Das 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.2

This study is an attempt to evaluate relative density and friction angle of sands on the basis of SPT-N values. In order to develop the relationships among relative density (Dr), friction angle (φ ) and SPT-N value, field and laboratory test results from sixty boreholes executed in sandy deposit were used. The field tests include the SPTs conducted in the boreholes and the determination of in-situ density at various depths in the boreholes using the pitcher sampler whereas the laboratory tests include routine classification, direct shear box, maximum and minimum density and specific gravity tests. The SPT-N values were observed to vary between 4 and 100 and the in-situ bulk density of undisturbed samples as recovered through pitcher sampler are in the range of 13.24 ~ 18.44 kN/m3. The soil samples are classified as poorly graded sand (SP), poorly graded sand with silt (SP-SM) and silty sand (SM) on the basis of Unified Soil Classification System. The values of minimum dry unit weight fall in the range of 12.22~14.95 kN/m3 and maximum dry unit weight varies in the range of 14.64~19.17 kN/m3 as obtained through vibratory table. Based on the test results, correlation analysis was performed to identify the parameters that affect relative density. The parameters include SPT-N value corrected for field procedures (N60), relative density (Dr), void ratio range ( ), effective overburden stresses and in-situ dry density (γdf). Based on the results of correlation analyses, it was observed that SPT-N values alone cannot be related to Dr. Therefore, multiple regression analysis was carried out using Statistical Package for the Social Sciences (SPSS) software and relation between relative density, corrected SPT-N value and effective overburden stress is being proposed. The variation between experimental and predicted values falls within ± 10% at 95% confidence interval. Validation of the proposed correlation was also performed by using an independent data set which indicated that the prediction by using the proposed correlation also falls within ± 10%. Further, comparison of the proposed correlation with other similar relationships already available in the literature was also performed. In addition to the above, correlation between φ and SPT-N60 has also been proposed. It has been observed that the experimental and predicted values of friction angle fall within ± 10% with 95% confidence interval. The proposed correlations may be very useful in the field of geotechnical engineering during feasibility/preliminary design stage for rapid estimation of relative density or friction angle based on the field SPT-N60 values.

Residual effects of monoammonium phosphate, gypsum and elemental sulfur on cadmium phytoavailability and translocation from soil to wheat in an effluent irrigated field

Qayyum, Muhammad Farooq,Rehman, Muhammad Zia ur,Ali, Shafaqat,Rizwan, Muhammad,Naeem, Asif,Maqsood, Muhammad Aamer,Khalid, Hinnan,Rinklebe, Jö,rg,Ok, Yong Sik Elsevier 2017 CHEMOSPHERE - Vol.174 No.-

<P><B>Abstract</B></P> <P>Cadmium (Cd) accumulation in agricultural soils is one of the major threats to food security. The application of inorganic amendments such as mono-ammonium phosphate (MAP), gypsum and elemental sulfur (S) could alleviate the negative effects of Cd in crops. However, their long-term residual effects on decreasing Cd uptake in latter crops remain unclear. A field that had previously been applied with treatments including control and 0.2, 0.4 and 0.8% by weight of each MAP, gypsum and S, and grown with wheat and rice and thereafter wheat in the rotation was selected for this study. Wheat (<I>Triticum aestivum</I> L.) was grown in the same field as the third crop without further application of amendments to evaluate the residual effects of the amendments on Cd uptake by wheat. Plants were harvested at maturity and grain, and straw yield along with Cd concentration in soil, straw, and grains was determined. The addition of MAP and gypsum significantly increased wheat growth and yield and decreased Cd accumulation in straw and grains compared to control while the reverse was found in S application. Both MAP and gypsum decreased AB-DTPA extractable Cd in soil while S increased the bioavailable Cd in soil. Both MAP and gypsum increased the Cd immobilization in the soil and S decreased Cd immobilization in a dose-additive manner. We conclude that MAP and gypsum had a significant residual effect on decreasing Cd uptake in wheat. The cost-benefit ratio revealed that gypsum is an effective amendment for decreasing Cd concentration in plants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Residual monoammonium phosphate (MAP) and gypsum reduced the Cd uptake in wheat. </LI> <LI> Amendment of residual elemental sulfur (S) increased Cd uptake in plants. </LI> <LI> Gypsum had the highest cost-benefit ratio compared with MAP and elemental S. </LI> <LI> Gypsum may be used to enhance crop production in Cd-contaminated soils. </LI> </UL> </P>

Study of hydrodynamics and iodine removal by self-priming venturi scrubber

Ahad Jawaria,Rizwan Talha,Farooq Amjad,Waheed Khalid,Ahmad Masroor,Qureshi Kamran Rasheed,Siddique Waseem,Irfan Naseem 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1

Filtered containment system is a passive safety system that controls the over-pressurization of containment in case of a design-based accidents by venting high pressure gaseous mixture, consisting of air, steam and radioactive particulate and gases like iodine, via a scrubbing system. An indigenous lab scale facility was developed for research on iodine removal by venturi scrubber by simulating the accidental scenario. A mixture of 0.2 % sodium thiosulphate and 0.5 % sodium hydroxide, was used in scrubbing column. A modified mathematical model was presented for iodine removal in venturi scrubber. Improvement in model was made by addition of important parameters like jet penetration length, bubble rise velocity and gas holdup which were not considered previously. Experiments were performed by varying hydrodynamic parameters like liquid level height and gas flow rates to see their effect on removal efficiency of iodine. Gas holdup was also measured for various liquid level heights and gas flowrates. Removal efficiency increased with increase in liquid level height and gas flowrate up to an optimum point beyond that efficiency was decreased. Experimental results of removal efficiency were compared with the predicted results, and they were found to be in good agreement. Maximum removal efficiency of 99.8% was obtained.

Sustainable Utilization of Powdered Glass to Improve the Mechanical Behavior of Fat Clay

Hassan Mujtaba,Usama Khalid,Khalid Farooq,Mehboob Elahi,Ziaur Rehman,Hussain Mustafa Shahzad 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12

Civil engineering infrastructure like roads, bridges, railway tracks, and building structures constructed on fat clay becomes suspicious due to adverse change in the behavior of such soil on interaction with water. To solve such problems especially in underdeveloped countries, application of industrial waste like glass is associated with technical, financial, and environmentalbenefits. Emphasis of current study is to determine the consequences of powdered glass (GC) on mechanical behavior of fat clay. A fat clayey sample was collected from location of Nandipur, and glass was taken from local glass market in powdered form. Samples were remolded at optimum moisture content and maximum dry unit weight by mixing GC up to 14%. Soil classification tests, modified compaction tests, unconfined compression tests, one-dimensional consolidation tests, California bearing ratio (CBR) tests, and scanning electron microscope were performed. With increasing GC, the consistency limits, compression characteristics, swell characteristics, and optimum moisture content decreased while maximum dry unit weight, yield stress, CBR, and unconfined compression strength increased. Influence of GC is also observed on microstructure of treated clay. After 12% GC, aforementioned geotechnical characteristics behave inversely for selected clay. The optimum GC-value for the tested clay is about 12%, however, this value may vary from clay to clay.

New Mg0.5CoxZn0.5xFe2O4 nano-ferrites: Structural elucidation and electromagnetic behavior evaluation

Maria Yousaf Lodhi,Khalid Mahmood,Azhar Mahmood,Huma Malik,Muhammad Farooq Warsi,Imran Shakir,M. Asghar,Muhammad Azhar Khan 한국물리학회 2014 Current Applied Physics Vol.14 No.5

In this work cobalt substituted magnesium zinc nanocrystalline spinel ferrites having general formula Mg0.5CoxZn0.5xFe2O4 where x ¼ 0.1, 0.2, 0.3, 0.4, 0.5 were synthesized using micro-emulsion technique. The Co substituted samples annealed at 700 C and characterized by various characterization techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dielectric measurements and vibrating sample magnetometer (VSM). XRD analysis confirmed single phase spinel structure and the crystalline size calculated by Scherrer’s formula found to be in 21.38e45.5 nm range. The lattice constant decreases as substitution of Co is increased. The decrease in lattice constant is attributed to the smaller ionic radius of cobalt as compared to zinc ion. The FTIR spectra reveled two prominent frequency bands in the wave number range 400e600 cm1 which confirm the cubic spinel structure and completion of chemical reaction. The dielectric parameters were observed to decrease with the increased Co contents. The peaking behavior was observed beyond 1.8 GHz. The frequency dependent dielectric properties of all these nanomaterials have been explained qualitatively in accordance with Koop’s phenomenological theory. Magnetic studies revealed that the coercivity (Hc) attains maximum value of 818 Oe at w21 nm. The increasing trend of magnetic parameters (coercivity and retentivity) is consistent with crystallinity. The crystallite size is small enough to attain considerable signal to noise ratio in high density recording media. The optimized magnetic parameters suggest that the material with composition Mg0.5Co0.5Fe2O4 may have potential applications in high density recording media.

Process interoperability in healthcare systems with dynamic semantic web services

Khan, Wajahat Ali,Hussain, Maqbool,Latif, Khalid,Afzal, Muhammad,Ahmad, Farooq,Lee, Sungyoung Springer-Verlag 2013 Computing Vol.95 No.9

Investigation of dust particle removal effi ciency of self-priming venturi scrubber using computational fl uid dynamics

Sarim Ahmed,Hassan Mohsin,Kamran Qureshi,Ajmal Shah,Waseem Siddique,Khalid Waheed,Naseem Irfan,Masroor Ahmad,Amjad Farooq 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.5

A venturi scrubber is an important element of Filtered Containment Venting System (FCVS) for theremoval of aerosols in contaminated air. The present work involves computational fluid dynamics(CFD) study of dust particle removal efficiency of a venturi scrubber operating in self-priming mode usingANSYS CFX. Titanium oxide (TiO2) particles having sizes of 1 micron have been taken as dust particles. CFD methodology to simulate the venturi scrubber has been first developed. The cascade atomizationand breakup (CAB) model has been used to predict deformation of water droplets, whereas the EulerianeLagrangian approach has been used to handle multiphase flow involving air, dust, and water. Thedeveloped methodology has been applied to simulate venturi scrubber geometry taken from the literature. Dust particle removal efficiency has been calculated for forced feed operation of venturi scrubberand found to be in good agreement with the results available in the literature. In the second part, venturiscrubber along with a tank has been modeled in CFX, and transient simulations have been performed tostudy self-priming phenomenon. Self-priming has been observed by plotting the velocity vector fields ofwater. Suction of water in the venturi scrubber occurred due to the difference between static pressure inthe venturi scrubber and the hydrostatic pressure of water inside the tank. Dust particle removal efficiencyhas been calculated for inlet air velocities of 1 m/s and 3 m/s. It has been observed that removalefficiency is higher in case of higher inlet air velocity.