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CONTENTS
Volume 11, Number 4, July 2020
 

Abstract
The effects of the mixed two solvents, Dimethylacetamide (DMAc) and Dimethylformamide (DMF), and Polyethylene glycol (PEG) and Polyvinylpyrrolidone (PVP) as additives on performance of Polyvinylidene fluoride (PVDF) membranes were studied. Initially, PEG200 was used as a primary additive at fixed percentage of 5% wt. PVP was then blended with PEG200 in different concentrations. PVDF and DMAc were used as polymer and solvent in the casting solutions, respectively. To control the diffusion rate of PVP in the presence of PEG200 and PVP blend, mixtures of DMAc and DMF were used as the mixed solvent in the casting solutions. Asymmetric PVDF membranes were prepared via phase inversion process in a water bath and the effects of two additives and two solvents on the membrane morphology, pure water flux (PWF), hydrophilicity and rejection (R) were investigated. Attenuated Total Reflection Fourier Transform Infrared Spectra (ATR-FTIR) analysis was used to show the residual PVP on the surface of the membranes. Atomic Force Microscopy (AFM) was utilized to determine roughness of membrane surface. The use of mixed solvents in the casting solution resulted in reduction of PVP diffusion rate and increment of PEG diffusion rate. Eventually, PWF and R values reduced, while porosity and hydrophilicity increased.

Key Words
PVDF membranes; blending; PEG/PVP; mixed solvents; DMAc/DMF

Address
Shima Rajabi, Foroogh Khodadadi, Toraj Mohammadi: Chemical Engineering Department, Iran University of Science and Technology, Narmak, Tehran, Iran
Maryam Tavakolmoghadam and Fatemeh Rekabdar: Research Institute of Petroleum Industry, Tehran, Iran

Abstract
Sand filter is a key unit process for particle removal in water purification treatments. Its long-standing use is due to on-site customized retrofit. Proper selection of filter media is one of the retrofit approaches to improve filter performance. This study described a series of controlled laboratory column tests and examined the effects of media property on filtration and backwash. When sand media of 0.51 mm in effective size was replaced by sand of 0.60 mm, the filter run increased up to 5 times in the given bed depth. The change of media property required an increase of backwash rate by 0.05 m/min to satisfy the requirement of bed expansion, more than 20%. When the anthracite was changed with lower effective size and uniformity coefficient, correlation with sand in the filter bed could be satisfied within the permissible error between media and bulk characteristics. Besides, this selection resulted in a well-stratified configuration of media layers after bed expansion. The column study showed that the correlation of property between the dual media had a significant effect on the filter productivity and backwash interval.

Key Words
backwash; bed expansion; filter media; mixed layer; retrofit; ieve analysis

Address
Tae-hoon Kim and ChulHwi Park: Department of Environmental Engineering, University of Seoul, 163 Seoul siripdaero, Dongdaemun-gu, Seoul, Republic of Korea
Heekyong Oh, Jungyeol Eom: Plant Research Team, Daewoo E&C, 20 Suil-ro 123beon-gil, Jangan-gu, Suwon-si, Gyeonggi-do, Republic of Korea

Abstract
There are many previous review articles are available to summarize either the characterization methods of effluent organic matter (EfOM) or the individual control treatment options. However, there has been no attempt made to compare in parallel the physicochemical treatment options that target the removal of EfOM from biological treatments. This review deals with the recent progress on the characterization of EfOM and the novel technologies developed for EfOM treatment. Based on the publications after 2010, the advantages and the limitations of several popularly used analytical tools are discussed for EfOM characterization, which include UV-visible and fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC), and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). It is a recent trend to combine an SEC system with various types of detectors, because it can successfully track the chemical/functional composition of EfOM, which varies across a continuum of different molecular sizes. FT-ICR-MS is the most powerful tool to detect EfOM at molecular levels. However, it is noted that this method has rarely been utilized to understand the changes of EfOM in pre-treatment or post-treatment systems. Although membrane filtration is still the preferred method to treat EfOM before its discharge due to its high separation selectivity, the minimum requirements for additional chemicals, the ease of scaling up, and the continuous operation, recent advances in ion exchange and advanced oxidation processes are greatly noteworthy. Recent progress in the non-membrane technologies, which are based on novel materials, are expected to enhance the removal efficiency of EfOM and even make it feasible to selectively remove undesirable fractions/compounds from bulk EfOM.

Key Words
organic matter; wastewater; oxidation; membrane; removal

Address
Schindra Kumar Ray, Hai Bang Truong, Zeshan Arshad and Jin Hur: Department of Environment and Energy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Korea
Hyun Sang Shin: Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Korea

Abstract
Hranfa's marl, a local natural mineral, is selected for the decontamination by adsorption of aqueous effluents in textile industry. Its physicochemical characterization is first performed. It is composed mainly of Calcite, Quartz, Ankerite and Muscovite. Its specific surface area is 40 m2g-1. Its adsorption performance is then tested in batch conditions using an industrial organic dye, Bemacid Red E-TL, as a model pollutant. The measured adsorption capacity of Hranfa's marl is 16 mg g-1 which is comparable to that of other types of natural adsorbents. A hybrid process is tested coupling adsorption of the dye on marl in suspension and microfiltration. An adsorption reactor is inserted into the circulation loop of a microfiltration pilot using ceramic membranes. This makes possible a continuous extraction of the treated water provided that a periodic replacement of the saturated adsorbent is done. The breakthrough curve obtained by analyzing the dye concentration in the permeate is close to the ideal one considering that no dye will cross the membrane as long as the adsorbent load is not saturated. These first experimental data provide proof of concept for such a hybrid process.

Key Words
hybrid process, microfiltration by ceramic membrane, natural adsorbents, wastewater treatment

Address
Bakhta Maimoun, Abderrahmane Djafer, Lahcéne Djafer: Laboratoire Eau et Environnement, Hassiba Benbouali University, Chlef, Algeria
Rose-Marie Marin-Ayral: Institut Charles Gerhardt Montpellier, Univ Montpellier, Montpellier, France
André Ayral: Institut Européen des Membranes, Univ Montpellier, Montpellier, France


Abstract
This work aims at studying the feasibility of continuous removal of mixed heavy metal ions from simulated zinc plating wastewaters by coupling a microbial fuel cell and a microbial electrolysis cell in batch and continuous modes. The discharging voltage of MFC increased initially from 0.4621 ± 0.0005 V to 0.4864 ± 0.0006 V as the initial concentration of Cr6+ increased from 10 ppm to 60 ppm. Almost complete removal of Cr6+ and low removal of Cu2+ occurred in MFC of the MFC-MEC-coupled system after 8 hours under the batch mode; removal efficiencies (REs) of Cr6+ and Cu2+ were 99.76% and 30.49%. After the same reaction time, REs of nickel and zinc ions were 55.15% and 76.21% in its MEC. Cu2+, Ni2+, and Zn2+ removal efficiencies of 54.98%, 30.63%, 55.04%, and 75.35% were achieved in the effluent within optimum HRT of 2 hours under the continuous mode. The incomplete removal of Cu2+, Ni2+ and Zn2+ ions in the effluent was due to the fact that the Cr6+ was almost completely consumed at the end of MFC reaction. After HRT of 12 hours, at the different sampling locations, Cr6+ and Cu2+ removal efficiencies in the cathodic chamber of MFC were 89.95% and 34.69%, respectively. 94.58%, 33.95%, 56.57%, and 75.76% were achieved for Cr6+, Cu2+, Ni2+ and Zn2+ in the cathodic chamber of MEC. It can be concluded that those metal ions can be removed completely by repeatedly passing high concentration of Cr6+ through the cathode chamber of MFC of the MFC-MEC-coupled system.

Key Words
microbial fuel cell; microbial electrolytic cell; removal of mixed heavy metal ions; removal efficiency; hydraulic retention time; wastewater treatment

Address
Guo R. Xie, Chan S. Choi: Department of Applied Chemistry, Daejeon University, 62 Daehak-ro, Dong-gu, Daejeon, 34520, Republic of Korea
Bong S. Lim and Shao X. Chu: Department of Environmental Engineering, Daejeon University, 62 Daehak-ro, Dong-gu, Daejeon, 34520, Republic of Korea

Abstract
In this paper, theoretical approach with applications of the periodic wave solutions in an elastic material is applied by study the effect of initial stress, and rotation, on the radial displacement and the corresponding stresses in non-homogeneous orthotropic material. An Analytical solution for the elastodynamic equation has obtained concerning the component of displacement. The variations of stresses and displacements have shown graphically. Comparisons with previously published results in the absence of initial stress, rotation and non-homogeneity have made. Finally, numerical results have given and illustrated graphically for each case considered.

Key Words
periodic wave; initial stress; rotation; non-homogeneous; elastic body

Address
Ahmed Ramady, S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University. Jeddah 21589, Saudi Arabia
Ahmed Ramady: Department of Mathematics, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
H.A. Atia: Mathematics Department, Arts - Rabigh& College of Sciences, King Abdulaziz University, Rabigh 25732, Saudi Arabia
H.A. Atia: Department of Mathematics, Faculty of Science, Zagazig, University,Zagazig, Egypt

Abstract
This study aims to investigate at a laboratory scale fluorides removal from an industrial wastewater having excessive F- concentration through a hybrid process combining neutralization and membrane separation. For the membrane separation operation, both Reverse Osmosis (RO) and Nanofiltration (NF) were investigated and confronted. The optimized neutralization step with hydrated lime allowed reaching fluoride removal rates of 99.1 ± 0.4 %. To simulate continuous process, consecutive batch treatments with full recirculation of membrane process brines were conducted. Despite the relatively high super saturations with respect to CaF2, no membrane cloaking was observed. The RO polishing treatment allowed decreasing the permeate fluoride concentration to 0.9 ± 0.3 mg/L with a fluoride rejection rate of 93± 2% at the optimal transmembrane pressure of around 100 psi. When NF membrane was used to treat neutralization filtrate, the permeate fluoride concentration dropped to 1.1± 0.4 mg/L with a fluoride rejection rate of 88± 5% at the optimal pressure of around 80 psi. Thus, with respect to RO, NF allowed roughly 20% decrease of the driving pressure at the expense of only 5% drop of rejection rate. Both NF and RO permeates at optimal operating transmembrane pressures respect environmental regulations for reject streams discharge into the environment.

Key Words
industrial wastewater; fluoride removal; hybrid treatment process; neutralization; reverse osmosis; nanofiltration; optimization

Address
Nouha Meftah, Abdessalem Ezzeddine and Ahmed Hannachi: University of Gabes, National Engineering School of Gabes, Chemical Process Engineering Department,
Process Engineering and Industrial System Research Laboratory, Omar Ibn El khattab Street, 6029 Zrig, Gabes, Tunisia
Nouha Meftah, Ahmed Bedoui: University of Gabes, Faculty of Sciences of Gabes, Department of Chemistry, Erriadh City, 6072 Zrig, Gabes Tunisia



Abstract
ACF preparation from different materials and its application in constructed wetlands for wastewater treatment has been focused in environmental field. Different materials have been used to prepare ACF around the world. This study aims to prepare, characterize and use of ACF from loofah for removal of Tetracycline from water through composite vertical flow constructed wetlands. ACF was prepared and it was tested for characterization, later it was used for removal of Tetracycline from water through composite vertical flow constructed wetlands. In composite vertical flow constructed wetlands, three HRTs were set according to the experiment, 1D, 2D, and 3D is individually. Samples were transported immediately from collection point to laboratory for analyzing. Samples were measured for Tetracycline (TC), Total Phosphorus (TP), and Total nitrogen and COD. Tetracycline absorbance with respective 356nm was obtained good and HRT is important factor. Results show that composite vertical flow constructed wetlands with ACF from luffa is best option and it is recommended to study further deep analysis.

Key Words
loofah; characterization of ACF; antibiotic removal; tetracycline; CVFCW; wetland plants

Address
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, China


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