Mohammad Al-Shannag

Degradation of dissolved diazinon pesticide in water using the high frequency of ultrasound wave.

This article aims to apply the ultrasound technique in the field of clean technology to protect environment. The principle of sonochemistry is conducted here to degrade pesticides in simulated industrial wastewater resulted from a factory manufacturing pesticides namely diazinon. Diazinon pesticide selected in this study for degradation under high frequency ultrasound wave. Three different initial concentrations of diazinon (800, 1200, and 1800 ppm), at different solution volumes were investigated in to degrade dissolved diazinon in water. Ultrasound device with 1.7 MHz, and 0.044 cm diameter, was used to study the degradation process. It is found that as the concentration of diazinon increased, the degradation is also increasing, and when the solution volume increases, the ability to degraded pesticides decreases. The experimental results showed an optimum condition achieved for degradation of diazinon at 1200 ppm as initial concentration and 50 ml solution volume. Kinetic modeling applied for the obtained results showed that the degradation of diazinon by high ultrasound frequency wave followed a pseudo-first-order model with apparent rate constant of around of 0.01 s(-1).

Enhancement of COD-Nutrients Removals and Filterability of Secondary Clarifier Municipal Wastewater Influent Using Electrocoagulation Technique

The present work studied experimentally the variations of some characteristics of the mixed liquor solution in wastewater treatment plants (WWTPs) under the effect of electrocoagulation (EC) technique. Unlike conventional methods, electrocoagulation was performed using cylindrical perforated iron electrodes to achieve a good distribution of the applied DC field onto the municipal wastewater. Effects of electrocoagulation time, applied voltage gradient, and aeration on the mixed liquor characteristics were considered. The study figured out the dependency of the local pH and oxidation potential reduction (OPR) values, near anode and cathode on these operational conditions. It was found that electrocoagulation process reached steady state conditions in no more than 60 minutes. At high voltage gradient (6 V/cm), the steady removal efficiencies of COD and nutrients exceeded 89%. While aeration showed moderate influence on removal efficiencies and wastewater sludge filterability, it significantly affected the pH and ORP near the electrodes especially at the low voltage gradient. Results also indicated that the sludge filterability was improved notably by increasing the voltage gradient to have minimal levels of specific-resistance to filtration (SRF).

Reduction of COD and TSS from Paper Industries Wastewater using Electro-Coagulation and Chemical Coagulation

The objective of the present study was to investigate experimentally the removal of total suspended solid (TSS) and chemical oxygen demand (COD) of wastewater from paper industries by electro-coagulation techniques solely, or with the aid of chemical flocculants. Electro-coagulation experiments were carried out using iron electrodes and either iron sulphate or calcium carbonate as chemical coagulants. A parametric study including the effect of the type of coagulant, initial pH, current density (CD), circulating flow rate, and electro-coagulation time, on the percent removals of TSS, and COD was considered to explore their role in improving the treatment performance. Without the aid of flocculants, electro-coagulation treatment was able to reduce TSS and COD concentrations up to 80%. In particular, electro-coagulation with the aid of iron sulphate or calcium carbonate as flocculants was found to have the highest removal levels that reach values in the range of 90–97%.

Effect of Radial Clearance on the Flow Between Corotating Disks in Fixed Cylindrical Enclosures

Numerical results are obtained for the isothermal laminar flow of air between a pair of disks attached to and rotating with a hub in a fixed cylindrical enclosure. The presence of radial clearances or gaps between the rims of the disks and the curved enclosure wall, and the finite thickness of the disks, are considered in the calculations. The gaps allow time- and circumferentially-dependent axially-directed air flow exchanges between the contiguous inter-disk spaces. As a consequence, axisymmetric calculations of the flow, whether using boundary conditions in the gaps or extended to include the entire flow domain, fail to faithfully reproduce the experimentally measured radial variations of the mean and rms circumferential velocity components in the inter-disk space. Likewise, three-dimensional calculations using the symmetry-plane boundary condition in the gaps also fail to reproduce these variations. In contrast, computationally intensive three-dimensional calculations of the entire flow domain, including the gaps, yield results in very good agreement with the measured mean and rms velocities

Application of Stefan–Maxwell approach to azeotropic separation by membrane distillation

Abstract A multicomponent mass transfer model based on the Stefan–Maxwell formalism is developed to predict membrane distillation performance in separating azeotropic mixtures. The developed model accounts for all coupling interactions between the diffusing species as well as for temperature and concentration polarization effects. The model is validated with previously published experimental data of propionic acid/water azeotropic mixture. The model predicts the effect of the process relevant parameters very well.

Bioconversion of paper mill sludge to bioethanol in the presence of accelerants or hydrogen peroxide pretreatment.

In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation.

Heavy metal ions removal from wastewater using electrocoagulation processes: A comprehensive review

ABSTRACT A vast number of publications have investigated the application of electrocoagulation (EC) process in heavy metal ions removal from wastewaters. Most of these studies were simple lab-scale using synthetic wastewater with the absence of holistic and systematic approach to consider the process complexity. This comprehensive review considers the fundamental aspects of EC processes such as mechanisms, kinetic models, and isotherm models used by different researchers. Furthermore, the impact of the main design and process operational parameters on the removal efficiency is discussed and analyzed. Many concluding remarks and perspectives are stated to give insights for possible future investigations.

Separation of yeast cells from aqueous solutions using magnetically stabilized fluidized beds

Aims:  To separate Saccharomyces cerevisiae cells from aqueous solutions using magnetically stabilized fluidized beds (MSFB) that utilize a horizontal magnetic field, and to study the effect of some parameters, such as bed porosity and height, liquid flow rate and inlet concentration on cell removal efficiency and breakthrough curves.

Application of Magnetically Stabilized Fluidized Beds for Cell Suspension Filtration from Aqueous Solutions

Abstract A magnetically stabilized fluidized bed (MSFBs) utilizing a transverse magnetic field was used to retain cells from cell suspension. The magnetic field permits bed expansion without mixing of the magnetic particles. The bed porosity increased by 75% when the magnetic field intensity increases to 110 mT. The effect of the magnetic field, suspension flow rate, bed height, initial concentration, and pH on the breakthrough curves was studied. According to the experimental results, increasing the initial concentration, flow rate, and pH leads to early breakthrough and inefficient deposition. Additionally, increasing the field intensity and bed height delays the breakthrough point.

Shear-Driven Flow in a Toroid of Square Cross Section

The two-dimensional wall-driven flow in a plane rectangular enclosure and the three-dimensional wall-driven flow in a parallelepiped of infinite length are limiting cases of the more general shear-driven flow that can be realized experimentally and modeled numerically in a toroid of rectangular cross section. Present visualization observations and numerical calculations of the shear-driven flow in a toroid of square cross section of characteristic side length D and radius of curvature R c reveal many of the features displayed by sheared fluids in plane enclosures and in parallelepipeds of infinite as well as finite length