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CONTENTS
Volume 8, Number 6, November 2017
 

Abstract
This study evaluates the performance of membrane bioreactor (MBR) coupled with a modified walnut shell granular activated carbon (WSGAC) for tannery wastewater treatment. For this purpose, a pilot with overall volume of 80L and 12 hours hydraulic retention time (HRT) is operated in three scenarios. Here, the chemical oxidation demand (COD) of wastewater is reduced more than 98% in both C:N ratios of 13 (S1) and 6.5 (S2). This performance also remains intact when alkalinity depletes and pH reduces below 6 (S3). The ammonium removal ranges between 99% (S2) and 70% (S3). The reliability of system in different operating conditions is due to high solids retention time and larger flocs formation in MBR. The average breakthrough periods of WSGAC are determined between 15 minutes (S2) and 25 minutes (S1). In this period, the overall nitrate removal of MBR-WSGAC exceeds 95%. It is also realized that adding no chemicals for alkalinity stabilization and consequently pH reduction of MBR effluent (S3) can slightly lengthen the breakthrough from 15 to 20 minutes. Consequently, MBR can successfully remove the organic content of tannery wastewater even in adverse operational conditions and provide proper influent for WSGAC.

Key Words
membrane bioreactor (MBR); granular activated carbon (GAC); Walnut shell; tannery wastewater treatment; nitrification

Address
Abolghasem Alighardashi and Mahyar Pakan : Department of Civil, Water and Environmental Engineering, Shahid Beheshti University,
Shahid Abbasspour Blvd., Tehranpars, P.O. Box: 167651719, Tehran, Iran
Shervin Jamshidi : Water and Wastewater Research Center, Water Research Institute (WRI), Shahid Abbasspour Blvd., Tehranpars, P.O. Box: 16765313, Tehran, Iran
Farshid Pajoum Shariati : Science and Research Branch, Islamic Azad University, Simon Bulivar Blvd.,
P.O. Box: 14515775, Tehran, Iran

Abstract
A multi-effect air gap membrane distillation (ME-AGMD) module for pesticide wastewater treatment is studied with internal heat recovery, sensible heat of brine recovery, number of stages and the use of fresh feed as cooling water in a single module is implemented in this study. A flat sheet polytetrafluroethylene (PTFE) membrane was used in the 4-stage ME-AGMD module. The maximum value of permeate flux could reach 38.62 L/m2h at feed -coolant water temperature difference about 52\'C. The performance parameter of the module like, specific energy consumption and gain output ratio (GOR) was investigated for the module with and without heat recovery. Also, the module performance was characterized with respect to the separation efficiency of several important water quality parameters. The removal efficiency of the module was found to be >98.8% irrespective water quality parameters. During the experiment the membrane fouling was caused due to the deposition of the salt/crystal on the membrane surface. The membrane fouling was controlled by membrane module washing cycle 9 h and also by acidification of the feed water (pH=4) using 0.1M HCl solution.

Key Words
membrane distillation; multi-effect air gap membrane distillation; wastewater treatment; pesticide wastewater

Address
Bhausaheb L. Pangarkar : Chemical Engineering Department, Sir Visvesvaraya Institute of Technology, Chincholi, Nashik,
(Affiliated to SavitribaiPhule Pune University, Pune), 422 102, India/
Chemical Engineering Department, College of Engineering and Technology, Akola
(Affiliated to the SantGadge Baba Amravati University, Amravati), 444 104, India
Samir K. Deshmukh : Chemical Engineering Department, Priyadarshini Institute of Engineering and Technology, Nagpur, 440 019,India
Prashant V. Thorat : Chemical Engineering Department, College of Engineering and Technology, Akola
(Affiliated to the SantGadge Baba Amravati University, Amravati), 444 104, India

Abstract
Membrane fouling in membrane bioreactor (MBR) remains a primary challenge for its wider application. The focus of this study to investigate the influence of iron distribution in activated sludge on gel layer fouling in MBR. Significant reduction in the transmembrane pressure (TMP) rise rates was observed in the presence of iron as result of retarding the gel layer formation time. The spatial distribution of iron had a significant impact on the stratification structure of extracellular polymeric substances (EPS) fractions, such as proteins (PN) and polysaccharides (PS). A mitigation of PN or PS from the supernatant to the EPS inner layers was observed in the presence of iron. Compared with the control reactor, the reduction in PN and PS of the supernatant and lower PN/PS rates of the LB-EPS were beneficial to decrease the membrane fouling potential during the gel layer formation. Consequently, the iron addition managed to control gel layer fouling could be a useful strategy in MBR.

Key Words
membrane bioreactor (MBR); gel layer fouling; extracellular polymeric substances (EPS); stratification structure; transmembrane pressure (TMP)

Address
Haifeng Zhang, Xin Lu and Haihuan Yu : School of Chemistry Engineering, Northeast Dianli University, Jilin 132012, Jilin, P.R. China
Lianfa Song : Department of Civil, Environmental and Construction Engineering, Texas Tech University,
Boston, Lubbock, TX 79409-1023, USA

Abstract
In the present study, the water desalination across the penta-graphene has been explored by using molecular dynamics simulation. The penta-graphene, a new carbon allotrope, introduced theoretically in 2015. It was shown that this carbon nanostructure is slightly stiffer against buckling in comparison with the graphene nanoribbons. The effect of radius of curvature (ROC) of the membrane, pore size, and applied pressure, on water flow rate, and salt rejection is investigated. It is shown that salt rejection, and the shape of the oxygen density distribution inside the pore can be influenced by the ROC of membrane. Finally, it is shown that the ROC, and pore size of 2D membranes, play an important role in the salt rejection.

Key Words
water desalination; penta-graphene membrane; radius of curvature; molecular dynamics simulation

Address
Sadollah Ebrahimi : Department of Physics, Faculty of Science, University of Kurdistan, Sanandaj, Iran
Research Center for Nanotechnology, University of Kurdistan, Sanandaj, Iran


Abstract
Antibacterial effective, high performanced, novel ZnO embedded composite membranes were obtained by blendig ZnO nanoparticles with polysulfone. IR, TG/DTG, XRD and SEM analysis were performed to characterize structure and morphology of ZnO nanoparticles and composite membranes. Contact angle, EWC, porosity and pore structure properties of composite membranes were investigated. Cross-flow filtration studies were performed to investigation of performances of prepared membranes. It was found from the cross section SEM images that ZnO nanoparticles dispersed homogenously up to additive amount of 2% and the membrane skin layer thicknesses increased in the presence of ZnO. Contact angle of pure PSf membranes were reduced from 70\' to 55\' after addition of 4% ZnO. Porositiy of composite membrane contains 1% ZnO was higher about 22% than pure PSf membrane. BSA rejection ratio and PWF of 0.5% ZnO embedded composite membrane became 2.2 and 2.3 times higher than pure PSf membrane. It was determined from flux recovery ratios that ZnO additive increased the fouling resistance of composite membranes. Also, the bacterial killing ability of ZnO is well known and there are many researches related to this in the literature. Therefore, it is expected that prepared composite membranes will show antibacterial effect.

Key Words
membrane; ultrafiltration; water treament; flux; antifouling

Address
Adem Sarihan : Higher Vocational School, Bilecik Seyh Edebali University, 11210, Bilecik, Turkey
Erdal Eren : Department of Chemistry, Faculty of Science and Arts, Bilecik Seyh Edebali University, 11210, Bilecik, Turkey

Abstract
PolyHIPEs membrane prepared with styrene (St), divinylbenzene (DVB), and ethylhexyl acrylate (EHA) can yield a unique pore structure provided by large voids highly interconnected by many small window throats. With the advantageous pore structure, PolyHIPE presents a potential as a support for carrier facilitated transport membrane. Tricaprylmethylammonium chloride (Aliquat 336) can be efficiently incorporated into the PolyHIPE membrane by a two-step solvent-nonsolvent method to obtain an Aliquat 336-immobilized PolyHIPE membrane with good stability. The study of Cr (VI) transport through Aliquat 336-immobilized PolyHIPE membrane indicates that the membrane has high initial flux and maxima stripping flux (Jfo=15.01 (umol/m2s), Jsmax=6.15 (umol/m2s)). The reusability study shows that the Aliquat 336-immobilized PolyHIPE membrane can maintain high Cr(VI) recovery efficiency even after 15 cycles of operations. The developed membrane was also used in the separation of Cr (VI) from other anions (i.e., (SO4)2-and (NO3)-) and other cations (i.e., Ni (ll), Mg (ll) and Cu (ll)) with good selectivity.

Key Words
polyHIPE membrane; Cr(VI) separation; solvent-nonsolvent method

Address
Jyh-Herng Chen : Department of Materials and Mineral Resources Engineering, National Taipei University of Technology,
1, Section 3, Chung-Hsiao East Road, Taipei, 10608, Taiwan, R.O.C.
Le Thi Tuyet Mai and Kai-Chung Hsu : College of Engineering, National Taipei University of Technology, 1, Section 3, Chung-Hsiao East Road, Taipei, 10608, Taiwan, R.O.C.

Abstract
Increase in the hydrophilicity (HPCT) of polysulfone (PS) membrane and subsequently decrease in fouling can be achieved by surface modification of PS based membranes. Therefore, in this work, ultrafiltration membranes with increased HPCT were prepared using the enantiomeric tartaric acid (D-TA) and racemic tartaric acid (DL-TA). Phase inversion technique was used for the preparation of polyethylene glycol and TA blended PS membrane. Morphological analysis of the fabricated membranes was done by scanning electron microscope and atomic force microscopy. Bovine serum albumin (BSA) solution was taken for finding the permeation and rejection behavior of prepared membranes. Maximum BSA rejection was increased by 70.5% for the modified membrane.

Key Words
polysulfone; tartaric acid; hydrophilicity; chirality; polyethylene glycol

Address
N. Sharma and M.K. Purkait : Department of Chemical Engineering, Indian Institute of Technology Guwahati,
Guwahati - 781039, Assam, India

Abstract
We report the novel thin film composite RO membrane modified by graphene oxide. The thin film composite RO membrane was exposed to 2000 mg/l sodium hypochloride; thereafter it was subjected to different graphene oxide concentration ranging from 50 mg/l to 1000 mg/l in water. The resultant membrane was crosslinked with 5000 mg/l N-hydroxysuccinimide. The performance of different membranes were analysed by solute rejection and water-flux measurement. It was found that 100 mg/l graphene oxide exposure followed by 5000 mg/l N-hydroxysuccinimide treatment resulted in the membrane with the highest solute rejection of 97.78% and water-flux of 4.64 Liter per sqm per hour per bar g. The membranes were characterized by contact angle for hydrophilicity, scanning electron micrographs for surface morphology, energy dispersive X-Ray for chemical composition of the surface, Atomic force microscope for surface roughness, ATR-FTIR for chemical structure identification. It was found that the graphene oxide modified membrane increases the salt rejection performance after exposure to high-fouling water containing albumin. Highly hydrophilic, antifouling surface formation with the nanomaterial led to the improved membrane performance. Moreover, the protocol of incorporating nanomaterial by this post-treatment is simple and can be applied to any RO membrane after it is manufactured.

Key Words
thin film composite RO; graphene oxide; N-hydroxysuccinimide; antifouling; hydrophilic

Address
Hiren D. Raval and Ravi Kiran Das : CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Council of Scientific & Industrial Research (CSIR), Gijubhai Badheka Marg, Bhavnagar- 364 002, Gujarat India


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