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Item type:Publication, Access status: without files , Mathematical modeling of arsenic(V) adsorption onto iron oxyhydroxides in an adsorption-submerged membrane hybrid systemThe adsorption of arsenic (V), As(V), on two porous iron oxyhydroxide-based adsorbents, namely, micro-sized tetravalent manganese feroxyhyte (μTMF) and granular ferric hydroxide (μGFH), applied in a submerged microfiltration membrane hybrid system has been investigated and modeled. Batch adsorption tests were carried out to determine adsorption equilibrium and kinetics parameters of As(V) in a bench-scale slurry reactor setup. A mathematical model has been developed to describe the kinetic data as well as to predict the As(V) breakthrough curves in the hybrid system based on the homogeneous surface diffusion model (HSDM) and the corresponding solute mass balance equation. The kinetic parameters describing the mass transfer resistance due to intraparticle surface diffusion (Ds) involved in the HSDM was determined. The fitted Ds values for the smaller (1–63 μm) and larger (1–250 μm) diameter particles of μGFH and μTMF were estimated to be 1.09 × 10−18 m2/s and 1.53 × 10-16 m2/s, and 2.26 × 10−18 m2/s and 1.01 × 10-16 m2/s, respectively. The estimated values of mass transfer coefficient/ kinetic parameters are then applied in the developed model to predict the As(V) concentration profiles in the effluent of the hybrid membrane system. The predicted results were compared with experimental data for As(V) removal and showed an excellent agreement. After validation at varying adsorbent doses and membrane fluxes, the developed mathematical model was used to predict the influence of different operation conditions on As(V) effluent concentration profile. The model simulations also exhibit that the hybrid system benefits from increasing the amount of adsorbent initially dosed and from decreasing the membrane flux (increasing the contact time).Publicationtype: Journal Article114 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Investigation of input and output energy for wheat production : a comprehensive study for Tehsil Mailsi (Pakistan)(Multidisciplinary Digital Publishing Institute (MDPI), 2020-08-24); ; ; ; The global increasing food demand can be met by efficient energy utilization in mechanized agricultural productions. In this study, input–output energy flow along with CO2 emissions for different wheat production cases (C-I to C-V) were investigated to identify the one that is most energy-efficient and environment-friendly case. Data and information about input and output sources were collected from farmers through questionnaires and face-to-face interviews. Input and output sources were converted into energy units by energy equivalents while CO2 emissions were calculated by emission equivalents. Data envelopment analysis (DEA) was conducted to compare technical efficiencies of the developed cases for optimization of inputs in inefficient cases. Results revealed that case C-Ⅴ (higher inputs, larger fields, the tendency of higher fertilizer application and tillage operations) has the highest energy inputs and outputs than the rest of the cases. Moreover, it possesses the lowest energy use efficiency and energy productivity. The highest CO2 emissions (1548 kg-CO2/ha) referred to C-Ⅴ while lowest emissions per ton of grain yield were determined in C-Ⅳ (higher electricity water pumping, moderate energy input). The grain yield increases directly with input energy in most of the cases, but it does not guarantee the highest values for energy indices. C-Ⅲ (moderate irrigations, educated farmers, various fertilizer applications) was found as an optimum case because of higher energy indices like energy use efficiency of 4.4 and energy productivity of 153.94 kg/GJ. Optimum input and better management practices may enhance energy proficiency and limit the traditionally uncontrolled CO2 emissions from wheat production. Therefore, the agricultural practices performed in C-Ⅲ are recommended for efficient cultivation of wheat in the studied area.Publicationtype: Journal ArticleScopus© Citations 16 166 223 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimization of soil aquifer treatment by chemical oxidation with hydrogen peroxide additionTrace organic compounds (TrOCs), mostly found in secondary effluents have a potential impact on the environment including surface water, groundwater and especially aquatic ecosystems. This study focuses on the oxidation of five selected TrOCs in column experiments simulating soil aquifer treatment (SAT) integrated with Fenton-like reaction using granular ferric hydroxide (GFH) as a catalyst. In order to determine the effectiveness of removing TrOCs by water through this approach, experiments were carried out with ultrapure water containing different target compounds at pH 6 using different dosages of hydrogen peroxide and catalyst. In this study, the optimal concentration of hydrogen peroxide for the removal of TrOCs was found to be 200 mg/L. However, the observed overall removal was low for each target compound. Moreover, little increase in the chemical oxidation of micropollutants was observed by increasing the dosage of the catalyst. For an optimum concentration of hydrogen peroxide the removal of 33, 34, 28, 29 and 35% were observed for benzotriazole, carbamazepine, phenytoin, primidone and meprobamate, respectively in 5h with a hydraulic retention time of 3h, respectively. Therefore, this treatment scheme might not be a promising option for the oxidation of secondary effluents. Thus, other treatment options, such as decrease of pH, recirculation of effluent through columns to increase the hydraulic retention times, other types of catalyst and higher dosage of hydrogen peroxide need to be considered for more efficient removal of TrOCs within SAT integrated with Fenton-like reaction.Publicationtype: Journal Article145 155