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CONTENTS
Volume 6, Number 6, November 2015
 

Abstract
Carbolic Acid which is called phenol is one of the important starting and/or intermediate materials in various industrial processes. However, its excessive release into environment poses a threat to living organisms, as it is a highly carcinogens and hazardous pollutant even at the very low concentration. Thus removal of phenol from polluted environments is very crucial for sustainable remediation process. We developed a low cost adsorption method for separating phenol from a model aqueous solution. The phenol adsorption was studied using two adsorbents i.e., Amber lite XAD-16 and Amber lite XAD-7 HP with a constant amount of resin 0.1 g at varying aqueous phenol concentrations (50-200 mg L-1) at room temperature. We compared the efficacy of two phenol adsorbents for removing higher phenol concentrations from the media. We investigated equilibrium and kinetics studies of phenol adsorption employing Freundlich, Temkin and Langmuir isotherms. Amberlite XAD-16 performed better than Amberlite XAD-7 HP in terms of phenol removal efficiency that amounted to 95.52%. Pseudo second order model was highly fitted for both of the adsorption systems. The coefficient of determination (R2) with Langmuir isotherm was found to be 0.98 for Amberlite XAD-7 HP. However, Freundlich isotherm showed R2 value of 0.95 for Amberlite XAD-16, indicating that both isotherms could be described for the isotherms on XAD-7 HP and Amberlite XAD-16, respectively.

Key Words
carbolic acid; phenol; Amberlite XAD-16; Amberlite XAD-7 HP; freundlich; langmuir; Temkin

Address
(1) Hasan Uslu:
Beykent University, Engineering and Architecture Faculty, Chemical Engineering Department, Ayazağa, Ìstanbul, Turkey;
(2) Hasan Uslu, Hisham S. Bamufleh:
Department of Chemical & Materials Engineering, Faculty of Engineering, King Abdul-Aziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia.

Abstract
Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving the energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum-cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo steady state approach for equipment sizing and the dynamic optimization using overall system mathematical models. The s-SMDDS employing three MD configurations, including the air gap (AGMD), direct contact (DCMD) and vacuum (VMD) types, are optimized. The membrane area of each system is 11.5 m2. The AGMD system operated for 500 kg/day water production rate gives the lowest unit cost of $5.92/m3. The performance ratio and recovery ratio are 0.85 and 4.07%, respectively. For the commercial membrane employed in this study, the increase of membrane mass transfer coefficient up to two times is beneficial for cost reduction and the reduction of membrane heat transfer coefficient only affects the cost of the DCMD system.

Key Words
solar energy; desalination; membrane distillation; optimization; dynamic modeling

Address
Department of Chemical and Materials Engineering, Tamkang University, 151 Yingzhuan Rd., Tamsui Dist., New Taipei City, Taiwan (R.O.C.).

Abstract
This study demonstrates that low pressure membranes are the ideal choice for industrial and/or municipal wastewater treatment by showing some promising experimental results, understanding different membrane filtration models, studying the potential of membrane bioreactors (MBRs), considering ceramic membranes fabrication and illustrating the role of nanotechnology in membranes. Cost study calculations are included to determine the treatment cost as well as the initial cost of various membrane types. Results showed that integrated membranes are preferred over MBR in case of average capacities. However, higher capacity situations are the most economical choice for MBR. It is shown that the least treatment cost in MBR was about $0.13/m3. However, the $0.13/m3 is the theoretical cost which is very small compared to the actual average MBR treatment cost of $0.5/m3.

Key Words
MBR; treatment cost; membrane technology; RO; MF; UF; filtration model; nanoparticles; ceramic membrane fabrication; treatment experiments

Address
(1) Hisham A. Maddah:
Department of Chemical Engineering, King Abdulaziz University - Rabigh Branch (KAU), Rabigh, Postal Code: 21911, PO Box 344, Saudi Arabia;
(2) Hisham A. Maddah, Aman M. Chogle:
Department of Chemical Engineering, University of Southern California (USC), 925 Bloom Walk, HED 216, Los Angeles, CA 90089-121, United States.

Abstract
In this work, treatment of real hypersaline refinery wastewater by hollow fiber membrane bioreactor coupled with reverse osmosis unit was studied. The ability of HF-MBR and RO developed in this work, was evaluated through examination of the effluent properties under various operating conditions including hydraulic retention time and flux. Arak refinery wastewater was employed as influent of the bioreactor which consists of an immersed ultrafiltation membrane. The HF-MBR/RO was run for 6 months. Average elimination performance of chemical oxygen demand, biological oxygen demand, total suspended solids, volatile suspended solids , total dissolved soild and turbidity were obtained 82%, 89%, 98%, 99%, 99% and 98% respectively. Highly removal performance of oily contaminant, TDS and the complete retention of suspends solids implies good potential of the HF-MBR/RO system for wastewater refinement.

Key Words
Hollow Fiber Membrane Bioreactor (HF-MBR); refinery wastewater; wastewater treatment; BOD5; COD; RO

Address
Department of Chemical Engineering, Faculty of Engineering, Arak University, Arak 38156-8-8349, Iran.


Abstract
A laboratory-scale submerged membrane bioreactor (MBR) was continuously operated for 100 d at an infinite sludge retention time (SRT) with the aim of identifying possible relation between the filterability of mixed liquor and sludge properties, such as extracellular polymeric substances (EPS), soluble microbial products (SMP), viscosity of mixed liquor, zeta potential of flocs and particle size distributions (PSD). Research results confirmed that MBR can operate with a complete sludge retention ensuring good treatment performances for COD and NH3-N. However, the long term operation (about 40 d) of MBR with no sludge discharge had a negative influence on sludge filterability, and an increase in membrane fouling rates with the time was observed. There as a strong correlation between the sludge filterability and the fouling rate. Among the different sludge properties parameters, the concentration SMP and EPS had a more closely correlation with the sludge filterability. The concentrations of SMP, especially SMP with MW above 10 kDa, had a strong direct correlation to the filterability of mixed sludge. The protein fractions in EPS were biodegradable and available for microorganism metabolism after about 60 days, and the carbohydrates in EPS had a significantly negative effect on sludge filterability in MBR at an infinite SRT.

Key Words
membrane bioreactor (MBR); sludge retention time (SRT); activated sludge; soluble microbial products (SMP); extracellular polymeric substances (EPS)

Address
(1) Haifeng Zhang, Bing Wang, Haihuan Yu, Lanhe Zhang:
School of Chemistry Engineering, Northeast Dianli University, Jilin 132012, Jilin, P.R. China;
(2) Lianfa Song:
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Boston, Lubbock, TX 79409-1023, USA.

Abstract
In this study, the effects of the angles of spacer filaments and the different feed Reynolds number on the fluid flow behavior have been investigated. Three-dimensional computational fluid dynamics (CFD) study is carried out for fluid flow through rectangular channels within different angles (30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, respectively) between two filaments of spacer for membrane modules. The results show that the feed Reynolds number and the angles of spacer filaments have an important influence on pressure drop. While the feed Reynolds number is fixed, the optimal angle of spacer should be between 80° to 90°, because the pressure drop is not only relatively small, but also high flow rate region expanded significantly with the increase of the angles between 80° to 90°.The Contours of velocities and change of the average shear stress with the different angle of spacer filaments confirm the conclusion.

Key Words
computational fluid dynamics (CFD); membrane spacers; pressure drop

Address
(1) Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, China;
(2) College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, Shandong Province, Chin


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