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CONTENTS
Volume 3, Number 2, May 2012
 

Abstract


Key Words


Address


Abstract
A two-dimensional (2D) steady state numerical model of concentration polarisation (CP) phenomena in a membrane channel has been developed using the commercially available computational fluid dynamics (CFD) package CFX (Ansys, Inc., USA). The model incorporates the transmembrane pressure (TMP), axially variable permeate flux, variable diffusivity and viscosity, and osmotic pressure effects. The model has been verified against several benchmark analytical and empirical solutions from the membrane literature. Additionally, the model is able to predict the rejection of an arbitrary solute by the membrane using a pore model, given some basic knowledge of the geometry of the solute molecule or particle, and the membrane pore geometry. This allows for predictive design of membrane systems without experimental determination of the membrane rejection for the specified operating conditions. A demonstration of the model is presented against experimental results for two uncharged test compounds (sucrose and PEG1000) from the literature. The model will be extended to incorporate charge effects, transient simulations, three-dimensional (3D) geometry and turbulent effects in future work.

Key Words
CFD; concentration polarisation; membrane filtration; pore model; predicted rejection

Address
School of Engineering, Deakin University, Geelong, Australia

Abstract
The performance of ultrafiltration (UF) membranes with molecular weight cut off (MWCO) of 1000 and 3500 Da in clarifying sugar cane juice was investigated, as well as the performance of a nanofiltration (NF) membrane with MWCO of 200 Da and a reverse osmosis (RO) membrane in concentrating sugar cane juice. For both cases the sugar cane juice had been limed and partially clarified. The UF membranes were found to be effective at clarifying the sugar cane juice in terms of purity rise and reduction in turbidity, colour, starch and protein. A purity rise of approximately 6 was achieved by both UF membranes at trans-membrane pressures (TMP) from 15 to 25 bar. However, Brix reduction in the permeate was between 14.5 and 41.85% and 12.11 and 26.52% for 1000 Da and 3500 Da membranes respectively. For the 200 Da and RO membranes the Brix in the concentrate was increased from 7.65 to 12.3 after 3 hours of operation for the 200 Da membrane at a TMP of 10 bar, whilst the Brix in the concentrate was increased from 15.65 to 27.6 after 3 hours of operation for the RO membrane at a TMP of 35 bar. Overall, UF membranes were found to be unsuitable for clarification of sugar cane juice since significant amount of Brix is reduced in the permeate, whilst RO membranes were found to be effective for concentration of sugar cane juice.

Key Words
concentration; clarification; sugar cane juice; ultrafiltration; nanofiltration; reverse osmosis

Address
Veeriah Jegatheesan, Li Shu, Dimuth Navaratna : School of Engineering, Deakin University, Waurn Ponds Campus, Geelong, VIC 3217, Australia
Diep Dinh Phong and Adam Neilly : School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4811, Australia

Abstract
Up-flow multi-layer bioreactor (UMBR) is a hybrid system using dual sludge that consists of an up-flow multi-layer bioreactor as anaerobic/anoxic suspended growth microorganisms followed by an aeration tank. The UMBR acts as a primary settling tank, anaerobic/anoxic reactor, thickener which requires low energy due to mixing by up-flow stream. This study focused on using a pilot UMBR plant with capacity of 20-30 m3/day for domestic wastewater in HCMC. HRTs of UMBR and aeration tank were 4.8 h and 7.2 h, respectively. The average MLSS of UMBR ranged from 10,000-13,600 mg/l SS. Internal recycle rate and sludge return were 200-300% and 150-200%, respectively. The results obtained from this study at flow rate of 20 m3/day showed that removal of COD, SS, TKN, N-NH4, T-N, and color were 91%, 87%, 86%, 80%, 91% and 91%, respectively.

Key Words
UMBR; up-flow multi-layer bioreactor; nutrient removal; domestic wastewater

Address
Cao Duc Hung, Nguyen Ngoc Han, Nguyen Phuoc Dan*, Bui Xuan : Faculty of Environment, Ho Chi Minh City University of Technology, Vietnam
Thanh,Kwon J.C. and Lee E.T.: R&D Center, Ecodigm Co., Ltd., 306 DTV Post BI, Daejeon 305-501, Korea
Shin H.S. : Department of Civil and Environmental Engineering, KAIST, Daejon 305-701, Korea

Abstract
This study investigated the extraction and stripping performance of PIMs consisting of PVC and Aliquat 336. Extraction and stripping of three representative heavy metals - namely Cd2+, Cu2+, and Zn2+ - by the synthesized membranes were evaluated as a function of sodium chloride concentration and under different stripping solutions (0.01 M HNO3, Milli-Q water, 0.01 M HCl and 0.01 M NaOH), respectively. Results reported here indicate that the formation of negatively charged metal chloride complex species was responsible for the extraction of the target metal to PIMs. Experimental results and thermodynamic modeling of the speciation of chloro metal complexes further confirm that the extraction selectivity between Cd2+, Cu2+ and Zn2+ can be controlled by regulating the chloride concentration of the feed solution. An acidic solution without any chloride was the most effective stripping solution, followed by Milli-Q water, and a diluted hydrochloric acid solution. On the other hand, the stripping of metals from PIMs did not occur when a basic stripping solution was used.

Key Words
polymer inclusion membranes (PIMs); metal extraction; base polymer; PVC; Aliquat 336

Address
Sandra Adelung, Burkhard Lohrengel : Department of Process Engineering and Environmental Technology, Faculty of Engineering 2, Heilbronn University, Heilbonn, Germany
Long Duc Nghiem : Environmental Engineering, University of Wollongong, NSW 2522, Australia

Abstract
The overall performance of BNR-MBR, so-called Anoxic-Anaerobic-Aerobic Membrane Bioreactor (A3-MBR), developed for nutrient removal was studied to determine the efficiencies and mechanisms under different solid retention time (SRT). The reactor was fed by synthetic high-rise building wastewater with a COD:N:P ratio of 100:10:2.5. The results showed that TKN, TN and phosphorus removal by the system was higher than 95%, 93% and 80%, respectively. Nitrogen removal in the system was related to the simultaneous nitrification-denitrification (SND) reaction which removed all nitrogen forms in aerobic condition. SND reaction in the system occurred because of the large floc size formation. Phosphorus removal in the system related to the high phosphorus content in bacterial cells and the little effects of nitrate nitrogen on phosphorus release in the anaerobic condition. Therefore, high quality of treated effluent could be achieved with the A3-MBR system for various water reuse purposes.

Key Words
anoxic-anaerobic-aerobic membrane bioreactor (A3-MBR); biological nutrient removal (BNR); simultaneous nitrification-denitrification (SND); enhanced biological phosphorus removal (EBPR), high-rise buiding wastewater recycling

Address
C. Ratanatamskul and N. Glingeysorn : Department of Environmental Engineering, Chulalongkorn University, Bangkok, Thailand
K. Yamamoto : Department of Urban Engineering, University of Tokyo, Tokyo, Japan


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