Boron Removal in New Generation Reverse Osmosis (RO) Membranes Using Two-Pass RO without pH Adjustment, Feb 1, 2013
Boron removal using new generation RO membranes from several leading manufacturers under a second... more Boron removal using new generation RO membranes from several leading manufacturers under a second-pass configuration and without pH adjustment was studied. The study was conducted using seawater from the Arabian Gulf (higher salinity and temperatures than average seawater). Membranes from several manufacturers were tested under similar operational conditions and the same feed water source. It was found that significant boron rejections, as high as 96%, were successfully achieved, using readily-available commercial RO membranes under a two-pass configuration and without any pH adjustment. Moreover, single-pass configurations exhibited high salt and boron rejection results reaching 99% and 91%, respectively. First pass permeates had boron levels below 1.4 ppm, which are adequate to comply with the new WHO guidelines (2.4 ppm) and those of other countries such as Australia, Canada, and UAE, whose boron guideline thresholds are above 1.4 ppm. The paper also assesses the influence of several operational parameters such as feed water salinity, flow velocity, temperature and feed pressure in second pass on boron removal in this process. It was found that higher boron removals were obtained with higher feed velocity, higher second-pass pressures, and lower feed temperatures.
An electrode kinetics modelling strategy is roposed based on fundamental electrochemical, physico... more An electrode kinetics modelling strategy is roposed based on fundamental electrochemical, physicochemical and biological principles to describe bioelectrochemical systems with multiple electrode reactions. The strategy aims at building models capable of accurately describing chemistry changes based on measured current as well as using data from electrochemical techniques such as cyclic voltametry (CV) for electrode kinetics model calibration. These characteristics will help in assessing the technical feasibility of existing and prospective BES of interest.
The importance of mathematical modelling and simulation in water and wastewater treatment systems... more The importance of mathematical modelling and simulation in water and wastewater treatment systems cannot be overemphasized. However the use of these tools have been limited to researchers with programming expertise and the existing simulation packages do not offer the needed flexibility for research applications. Moreover, the speeds of the simulations have been a critical bottleneck especially for control design applications. Earlier efforts have been made to provide a generalized architecture that is flexible and easy to use by researchers with limited programming knowledge, using an Excel/MATLAB SFunction based methodology (ExSF). This work provides the next generation of those efforts using an Excel/C-compatible-Simulink based generalised model implementation architecture (ExCC) that allows for very quick model implementation and modification while achieving very competitive C-like simulation speeds. Moreover, a generalisation feature based on the use of thermodynamic equilibriu...
Effective and sensitive monitoring of human pathogenic bacteria in municipal wastewater treatment... more Effective and sensitive monitoring of human pathogenic bacteria in municipal wastewater treatment is important not only for managing public health risk related to treated wastewater reuse, but also for ensuring proper functioning of the treatment plant. In this study, three different 16S rRNA gene molecular analysis methodologies were employed to screen bacterial pathogens in samples collected at three different stages of an activated sludge plant. Overall bacterial diversity was analyzed using next generation sequencing (NGS) on the Illumina MiSeq platform, as well as PCR-DGGE followed by band sequencing. In addition, a microdiversity analysis was conducted using PCR-DGGE, targeting Escherichia coli. Bioinformatics analysis was performed using QIIME protocol by clustering sequences against the Human Pathogenic Bacteria Database. NGS data were also clustered against the Greengenes database for a genera-level diversity analysis. NGS proved to be the most effective approach screening the sequences of 21 potential human bacterial pathogens, while the E. coli microdiversity analysis yielded one (O157:H7 str. EDL933) out of the two E. coli strains picked up by NGS. Overall diversity using PCR-DGGE did not yield any pathogenic sequence matches even though a number of sequences matched the NGS results. Overall, sequences of Gram-negative pathogens decreased in relative abundance along the treatment train while those of Gram-positive pathogens increased.
In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, et... more In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2nd order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water.
Boron Removal in New Generation Reverse Osmosis (RO) Membranes Using Two-Pass RO without pH Adjustment, Feb 1, 2013
Boron removal using new generation RO membranes from several leading manufacturers under a second... more Boron removal using new generation RO membranes from several leading manufacturers under a second-pass configuration and without pH adjustment was studied. The study was conducted using seawater from the Arabian Gulf (higher salinity and temperatures than average seawater). Membranes from several manufacturers were tested under similar operational conditions and the same feed water source. It was found that significant boron rejections, as high as 96%, were successfully achieved, using readily-available commercial RO membranes under a two-pass configuration and without any pH adjustment. Moreover, single-pass configurations exhibited high salt and boron rejection results reaching 99% and 91%, respectively. First pass permeates had boron levels below 1.4 ppm, which are adequate to comply with the new WHO guidelines (2.4 ppm) and those of other countries such as Australia, Canada, and UAE, whose boron guideline thresholds are above 1.4 ppm. The paper also assesses the influence of several operational parameters such as feed water salinity, flow velocity, temperature and feed pressure in second pass on boron removal in this process. It was found that higher boron removals were obtained with higher feed velocity, higher second-pass pressures, and lower feed temperatures.
An electrode kinetics modelling strategy is roposed based on fundamental electrochemical, physico... more An electrode kinetics modelling strategy is roposed based on fundamental electrochemical, physicochemical and biological principles to describe bioelectrochemical systems with multiple electrode reactions. The strategy aims at building models capable of accurately describing chemistry changes based on measured current as well as using data from electrochemical techniques such as cyclic voltametry (CV) for electrode kinetics model calibration. These characteristics will help in assessing the technical feasibility of existing and prospective BES of interest.
The importance of mathematical modelling and simulation in water and wastewater treatment systems... more The importance of mathematical modelling and simulation in water and wastewater treatment systems cannot be overemphasized. However the use of these tools have been limited to researchers with programming expertise and the existing simulation packages do not offer the needed flexibility for research applications. Moreover, the speeds of the simulations have been a critical bottleneck especially for control design applications. Earlier efforts have been made to provide a generalized architecture that is flexible and easy to use by researchers with limited programming knowledge, using an Excel/MATLAB SFunction based methodology (ExSF). This work provides the next generation of those efforts using an Excel/C-compatible-Simulink based generalised model implementation architecture (ExCC) that allows for very quick model implementation and modification while achieving very competitive C-like simulation speeds. Moreover, a generalisation feature based on the use of thermodynamic equilibriu...
Effective and sensitive monitoring of human pathogenic bacteria in municipal wastewater treatment... more Effective and sensitive monitoring of human pathogenic bacteria in municipal wastewater treatment is important not only for managing public health risk related to treated wastewater reuse, but also for ensuring proper functioning of the treatment plant. In this study, three different 16S rRNA gene molecular analysis methodologies were employed to screen bacterial pathogens in samples collected at three different stages of an activated sludge plant. Overall bacterial diversity was analyzed using next generation sequencing (NGS) on the Illumina MiSeq platform, as well as PCR-DGGE followed by band sequencing. In addition, a microdiversity analysis was conducted using PCR-DGGE, targeting Escherichia coli. Bioinformatics analysis was performed using QIIME protocol by clustering sequences against the Human Pathogenic Bacteria Database. NGS data were also clustered against the Greengenes database for a genera-level diversity analysis. NGS proved to be the most effective approach screening the sequences of 21 potential human bacterial pathogens, while the E. coli microdiversity analysis yielded one (O157:H7 str. EDL933) out of the two E. coli strains picked up by NGS. Overall diversity using PCR-DGGE did not yield any pathogenic sequence matches even though a number of sequences matched the NGS results. Overall, sequences of Gram-negative pathogens decreased in relative abundance along the treatment train while those of Gram-positive pathogens increased.
In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, et... more In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2nd order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water.
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