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Volume 5, Number 3, July 2014

Organic compounds are adsorbed on RO/NF membranes, and the adsorption may influence the rejection of organic compounds by the membranes. Because almost RO/NF membranes are composite membranes, the results obtained by adsorption experiment with using membrane pieces are unable to avoid the influence by the support membrane. In this work, the interaction between membrane polymer and organic solutes was examined by an inverse HPLC methodology. Poly (m-phenylenetrimesoylate), the constituent of skin layer of RO/NF membranes, was coated on silica gel particles and used as a stationary phase for HPLC. When water was used as a mobile phase, almost hydrophilic aliphatic compounds were not effectively adsorbed on the stationary phase, although hydrophobic compounds were slightly adsorbed. The results indicated that the hydrophilic aliphatic compounds are useful probe solutes to examine the molecular sieving effect of a membrane. When water was used as a mobile phase, the aromatic compounds were strongly retained, and therefore CH3CN/H2O (30/70) was used as a mobile phase. It was revealed that the adsorption of aromatic compounds was controlled by stacking between solute and polymer and was hindered by non-planar structure and substituents.

Key Words
RO/NF membrane; polyamide; adsorption; organic solute; HPLC

(1) Yoshiaki Kiso, Katsuya Hosogi:
Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi 441-8586, Japan;
(2) Yuki Kamimoto:
EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603, Japan;
(3) Yong-Jun Jung:
Department of Environmental engineering, Catholic University of Pusan, Oryundae-ro, Geumjeong-gu, Busan, 609-757, Korea.

The efficiency of two metal ions (cadmium, zinc) removal from aqueous solutions by ultrafiltration (UF) and Polymer Enhanced Ultrafiltration (PEUF) processes were investigated in this work. The UF and PEUF studies were carried out using an ultrafiltration tangential cell system equipped with 5.000 MWCO regenerated cellulose. A water-soluble polymer: the polyacrylic acid (PAA) was used as complexant for PEUF experiments. The effects of transmembrane pressure, pH, metal ions and loading ratio on permeate fluxes and metal ions removals were evaluated. In UF process, permeate fluxes increase linearly with increasing pH for different transmembrane pressure, which may be the consequence of the formation of soluble metal hydroxyl complexes in the aqueous phase. In PEUF process, above pH 5.0, the Cd(II) retention reaches a plateau at 90% and Zn(II) at 80% for L = 5. Also, cadmium retention at different L is greater than zinc retention at pH varying from 5.0 to 9.0. In a mixture solution, cadmium retention is higher than zinc for different loading ratio, this is due to interactions between carboxylic groups of PAA and metal ions and more important with cadmium ions.

Key Words
cadmium; zinc; polymer enhanced ultrafiltration; removal efficiency; ultrafiltration

(1) Dorra Jellouli Ennigrou, Ferid Mokhtar:
Physical Chemistry Laboratory of Mineral Materials and Their Applications, National Center for Research in Materials Sciences, Technopark Borj Cedria, PO Box 73-8027 Soliman, Tunisia;
(2) Mourad Ben Sik Ali:
Desalination and water treatment Research unit, Faculty of Sciences of Tunis, El Manar II 2092, Tunisia;
(3) Mahmoud Dhahbi:
National Center for Research and Water Technology Technopark Borj Cedria, PO Box 273-8020 Soliman, Tunisia.

For the first time in Bangladesh, a bench scale membrane bioreactor (MBR) unit was tested in treating a textile wastewater in the industry premises of EOS Textile Mills LTD, Dhaka for three months. The performance of the unit was compared with that of the conventional activated sludge treatment plant, which is in operation in the same premises. The COD and BOD removal efficiency of the MBR unit reached to around 90% and 80% respectively in 20 days whereas the removal efficiency of the conventional treatment plant was as low as 40-50% and 38-40% respectively. The outlet COD and the BOD level for the MBR unit remained stable in spite of the fluctuation in the feed value, while the conventional effluent treatment plant (ETP) failed to keep any stabilized level. The performance of the MBR unit was much superior to that of the functional ETP and the water treated by the MBR system can meet disposal standard.

Key Words
COD; industrial wastewater; membrane bioreactor; MBR; textile industry

(1) Pradip Saha, Md. Zakir Hossain, Md. Salatul I. Mozumder, Md. Tamez Uddin, Md. Akhtarul Islam:
ShahJalal University of Science & Technology (SUST), Sylhet-3114, Bangladesh;
(2) Jan Hoinkis, Shamim A. Deowan:
University of Applied Sciences Karlsruhe, Moltkestr. 30, 76133 Karlsruhe, Germany;
(3) Enrico Drioli, Alberto Figoli:
Institute on Membrane Technology (ITM-CNR), 87030 Rende (CS), Italy.

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, 45°C for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

Key Words
cleaning agent; flux recovery; pressure; temperature; concentration; pH

(1) Muhammad Said:
Department of Chemistry, Faculty of Mathematics and Science, University of Sriwijaya, Palembang, Indonesia;
(2) Muhammad Said, Abdul Wahab Mohammad, Siti Rozaimah Sheikh Abdullah, Hassimi Abu Hasan:
Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, University Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
(3) Abdul Wahab Mohammad, Mohd Tusirin Mohd Nor:
Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia.

Simulations were conducted to predict supersaturation along Reverse Osmosis (RO) modules for seawater desalination. The modeling approach is based on the use of conservation principles and chemical equilibria equations along RO modules. Full Pitzer ion interactive forces model for concentrated solutions was implement to calculate activity coefficients. An average rejection rate for all ionic species was considered. Supersaturation has been used to assess scaling. Supersaturations with respect to all calcium carbonate forms and calcium sulfate were calculated up to 50% recovery rate in seawater RO desalination. The results for four different seawater qualities are shown. The predictions were in a good agreement with the experimental results.

Key Words
seawater; desalination; reverse osmosis modules; supersaturation; scaling assessment

(1) Houda Hchaichi, Saanoun Siwar, Ahmed Hannachi:
Laboratory of Process Engineering and Industrial Systems, National Engineering School of Gabes, University of Gabes, Ibnel khattab Street, 6029, Zrig Gabès, Tunisia;
(2) Hamza Elfil:
LabTEN-Water Research and Technologies Center, Soliman, Tunisia.

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