Removal of natural organic matter though membrane filtration and subsequent effect on disinfectant decay

This study aims to evaluate the effectiveness of membrane filtration in removing natural organic matters (NOMs) from four different source waters and the subsequent effect that it has on total chlorine (TC) demand of these waters. Source water samples were filtered sequentially through membranes with molecular weight cut-off of 3,500, 1,000 and 200 Da as well as RO membrane. The source waters and sequentially filtered samples were dosed with chlorine and the residual chlorine data were used to estimate the TC demand of these waters. A robust chlorine decay model constructed in AQUASIM software was used to do so. More than 80% of the chlorine demand in untreated surface water sources was found to be contributed mainly by NOMs that were larger than 3,500 Da. However, for water treated by granular filtration, the chlorine demand was found to be contributed by NOMs which were down to 200 Da. Sequential filtration through all four membranes reduced chlorine demand by more than 94% in surface waters and 84% in waters treated by granular filtration. Significant reduction in the formation of trihalomethane can be achieved if water is treated by appropriate membranes after granular media filtration. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

Storm water harvesting and reuse in Australia : enhanced sand filtration for the treatment of storm water

This study details the removal of common storm water pollutants along with heavy metals by enhanced sand filtration. Three filtration flow rates were trialled: 5, 10 and 20 m/h. The performance of each filter was rated on the ability to remove turbidity, suspended solids, dissolved solids, phosphorus, nitrogen, lead, copper and Zinc. Conventional sand filter was used as a performance benchmark, and compared with four sand filters that are enhanced with a nylon carpet fibre, polypropylene carpet fibre, Syrian carpet fibre-enhanced and alum sludge-enhanced sand filter. Carpet fibre-enhanced sand filtration was highly effective at filtering simulated storm water and in most cases performing well above the conventional sand filters. The carpet fibre-enhanced sand filters had no drop in flow rates over the 4 h filtration period with following removal rates: up to 90% total suspended solids, 70% zinc, 60% turbidity, 25% phosphorus, 15% nitrogen and 10% total dissolved solids. However, results showed that alum sludge-enhanced sand filter performed the highest, with removal rates up to 100% for total suspended solids, 80% zinc, 90% turbidity, up to 80% phosphorus, up to 40% nitrogen and 3% total dissolved solids. But the flow rates dropped approximately two-thirds of the original flow rates within the first hour. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

A review of computational fluid dynamics applications in pressure-driven membrane filtration

Ongoing advances in computational performance and numerics have led to computational fluid dynamics (CFD) becoming a ubiquitous modelling tool. However, CFD methods have only been adopted to simulate pressure-driven membrane filtration systems relatively recently. This paper reviews various approaches to describing the behaviour of these systems using CFD, beginning with the hydrodynamics of membrane channels, including discussion of laminar, turbulent, and transition flow regimes, with reference to the effects of osmotic pressure, concentration polarisation, and cake formation. The use of CFD in describing mass transfer through the membrane itself is then discussed, followed by some concluding comments on commercial membrane simulation packages and future research directions in membrane CFD. © 2013 Springer Science+Business Media Dordrecht.

Enhancement of the antifouling properties and filtration performance of poly(ethersulfone) ultrafiltration membranes by incorporation of nanoporous titania nanoparticles

Nanoporous titania nanoparticles (NTNs) were synthesized and used as an additive at a low concentration of 0.1-1 wt % in the fabrication of poly(ethersulfone) (PES) ultrafiltration membranes via non-solvent-induced phase separation. The structure and properties of nanoparticles were characterized using nitrogen sorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The NTNs have a size distribution with a particle size of mainly <100 nm and have a Brunauer, Emmett, and Teller surface area of ∼100 m2 g-1. The modified membranes were fabricated and investigated in terms of their pure water flux, solute rejection, and fouling resistance. The water permeability and molecular weight cutoffs (MWCOs) of membranes were determined under constant-pressure filtration in dead-end mode at 100 kPa. The membrane fouling resistance was characterized under constant flux operation using bovine serum albumin as a model foulant. The membranes were characterized in terms of morphology, porosity, pore size distribution, energy-dispersive X-ray spectroscopy, contact angle goniometry, surface free energy, and viscosity of the dope solution. Overall, the modified membrane showed increased wettability and reduced surface free energy and pore size. The modified UF membrane with 0.5 wt % NTN loading exhibited improved fouling resistance (fouling rate of 0.58 kPa/min compared to a rate of 0.70 kPa/min for the control membrane) with ∼80% water flux recovery. The same membrane showed an ∼20% increase in water flux, an improvement in MWCO, and a narrower pore size distribution.

The influence of processing techniques on the matrix distribution and filtration of clay in a fibre reinforced nanocomposite

A nano-modified matrix based on an epoxy resin and montmorillonite (MMT) layered silicates, was successfully infiltrated through 10 ply of carbon fibre preform. A combined fabrication process of a vacuum assisted resin infusion method (VARIM) followed by a rapid heating rate and mechanical vibration during cure, facilitated the infiltration of the nano-modified matrix through the preform. This was achieved by dispersing the MMT clay in the resin and ensuring that the viscosity of the nano-modified matrix remained low during fabrication. SEM-EDX (energy dispersive X-ray spectroscopy) spectra showed that chemical constituents within MMT clay including silicon, aluminium and magnesium elements had permeated through the fibre preform and were detected throughout the laminate. A homogeneous resin/particle distribution was achieved with the size of clay particles ranging from 100 nm to 1 μm.

Incorporating sustainability in textile effluent treatment facilities

Sustainable development encompasses environmental, social and
economic considerations. As such the stakeholders include industry, government, individuals and communities. When designing or operating an industrial plant, it is Insufficient to consider only the economic viability of the facility. This paper examines the background to current sustainability awareness and presents a case study that incorporates sustainability principles in the design of an efluent treatment plant for a textile plant. The likely design of the treatment system (electro flotation followed by filtration) will do more than just meet regulatory requirements, it will maximise possible reuse of water and so minimise environmental impact of the facility.

Toad atrial natriuretic peptide : cDNA cloning and functional analysis in isolated perfused kidneys

Complementary DNA (cDNA) encoding Bufo marinus (toad) preproatrial natriuretic peptide (preproANP) was isolated by reverse-transcription polymerase chain reaction. Sequence analysis of toad preproANP cDNA revealed an open reading frame of 150 amino acid residues, which shared 72% and 66% identity with Rana catesbeiana and Xenopus laevis preproANP, respectively. The deduced amino acid sequence of toad ANP that corresponded to ANP 1–24 of R. catesbeiana and Rana ridibunda was identical, but it differed by four residues from that of X. laevis. ANP mRNA transcripts were also shown to be expressed in the toad kidney. Subsequently, the effect of frog ANP (1–24) on renal function in toad was examined using a perfused kidney preparation. The arterial infusion of frog ANP caused a dose-dependent decrease in the arterial perfusion pressure that was associated with an increase in the glomerular filtration rate (GFR) and a renal natriuresis and diuresis. The renal natriuresis and diuresis resulted predominantly from an increased GFR rather than from direct tubular effects. This study demonstrates that ANP can regulate renal function, which suggests it may be involved in overall fluid volume regulation.

Photocatalytic degradation of dyes in wastewater using TiO2/UV in a flat-plate reactor

The photocatalyst TiO₂ with UV irradiation was used to degrade dyes in textile effluent in a flat-plate photoreactor. A test system was built with the reactor area of 1 x 0.3m2, UV light of six 36W-blacklight. TiO₂ powder P25 with BET surface area 50±15m2/g, average primary particle size 21 nm, purity> 99.5% and content of 83.9% anatase and 16.1 % rutile was used as the photocatalyst. A number of dyes commonly present in dyeing wastewater were tested in this study. The different operating parameters, such as dosage of photocatalyst, the structure of the reactor, flow rates through the flat-plate reactor, UV radiation intensity and tilted angle of the reactor, were investigated. The results showed that the photocatalytic process could efficiently remove most of the colour contained in the dyeing wastewater. It was experimentally observed that first-order kinetics was adequate for characterising the process. The flow rate and the tilted angle had some influence on the film thickness of the fluid in the reactor and the empirical correlation between the film thickness of the fluid and these two parameters was developed. The photoreaction rate was mainly determined by the film thickness of the fluid on the reactor surface and the dosage of the photocatalyst. Optimum operating parameters of the system were found to be at the film thickness of about 1.4mm and a TiO₂ dosage of 1 gIL. The higher the UV intensity, the faster the reaction rate was. The results of these experiments showed that this method has the great potential for colour removal from wastewater at commercial scale.

To overcome the common difficulty of separating the used TiO₂ suspension after treatment precipitation followed with filtration was used in this study to determine the separation efficiencies. On the other hand, TiO₂ in a small pillar shape was also studied for photocatalytic degradation of textile dye effluent. The pillar pellet was made in Oegussa Company, Germany ranging from 2.5 to 5.3mm long and with a diameter of 3.7mm. It was almost pure TiO₂ (83.2% anatase and 16.8% rutile), with a S-content of <20 ppm and a CI content of the order of 0.1 wt. %. No further elements are present in contents above 0.05 wt.%. The TiO₂ pillars were placed on the flat-plate reactor that was divided by the rectangular slots and irradiated under UV light when the treated solution went through the reactor. Four dyes and their mixtures were tested. The results showed that the photocatalytic process under this configuration efficiently remove the colour from textile dyeing effluent, and pillar shape TiO₂ photocatalyst was not dissolved in water and very easy to be separated from solution, enabling it to be reused many times. The first-order kinetics was adequate for characterising the photocatalytic degradation process and the photocatalytic performance was comparable to TiO₂ powder. It is believed that the TiO₂ pellet would be a preferable form of photocatalyst in applications for textile effluent treatment process, and other wastewater treatment processes.

Reverse osmosis membrane fouling and its control

Reverse osmosis (RO) membranes can be used to treat ground water, surface water and wastewater, but a major problem in RO membrane applications is fouling. Many studies have investigated the mechanisms of fouling in RO membranes and suggested various methods to control the membrane fouling. This paper reviews several aspects of RO membranes, such as the types of membrane fouling, their effects on RO membrane processes and fouling control technologies, focussed on the appropriate feed pretreatment technologies and cleaning methods, especially on the membrane filtration pretreatment processes, including microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF), which are the new trends in designing a pretreatment system in the application of RO.

Chemical characterisation of the oligosaccharides in hooded seal (Cystophora cristata) and Australian fur seal (Arctocephalus pusillus doriferus) milk

Carbohydrates were extracted from hooded seal milk, Crystophora cristata (family Phocidae). Free oligosaccharides were separated by gel filtration and then purified by ion exchange chromatography, gel filtration and preparative thin layer or paper chromatography and their structures determined by ¹H-NMR. The hooded seal milk was found to contain inositol and at least nine oligosaccharides, most of which had lacto-N-neotetraose or lacto-N-neohexaose as core units, similar to those in milk of other species of Carnivora such as bears (Ursidae). Their structures were as follows: Gal(β1-4)Glc (lactose); Fuc(α1-2)Gal(β1-4)Glc (2′-fucosyllactose); Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (lacto-N-neotetraose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (lacto-N-fucopentaose IV); Gal(β1-4)GlcNAc(β1-3)[Gal(β1-4)GlcNAc(β1-6)]Gal(1-4)Glc (lacto-N-neohexaose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)[Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monofucosyl lacto-N-neohexaose a); Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monofucosyl lacto-N-neohexaose b); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (difucosyl lacto-N-neohexaose); Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (para lacto-N-neohexaose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (monofucosyl para lacto-N-neohexaose). Milk of the Australian fur seal, Arctophalus pusillus doriferus (family Otariidae) contained inositol but no lactose or free oligosaccharides. These results, therefore, support the hypothesis that the milk of otariids, unlike that of phocids, contains no free reducing saccharides.

Purification and characterisation of endo-β-1,4-glucanase and laminarinase enzymes from the gecarcinid land crab Gecarcoidea natalis and the aquatic crayfish Cherax destructor

Laminarinase and endo-β-1,4-glucanase were purified and characterised from the midgut gland of the herbivorous land crab Gecarcoidea natalis and the crayfish Cherax destructor. The laminarinase isolated from G. natalis was estimated to have a molecular mass of 41 kDa by SDS-PAGE and 71 kDa by gel filtration chromatography. A similar discrepancy was noted for C. destructor. Possible reasons for this are discussed. Laminarinase (EC 3.2.1.6) from G. natalis had a V_max of 42.0 µmol reducing sugars produced min–¹ mg protein–¹, a K_m of 0.126% (w/v) and an optimum pH range of 5.5–7, and hydrolysed mainly β-1,3-glycosidic bonds. In addition to the hydrolysis of β-1,3-glycosidic bonds, laminarinase (EC 3.2.1.39) from C. destructor was capable of significant hydrolysis of β-1,4-glycosidic bonds. It had a V_max of 19.6 µmol reducing sugars produced min^–1 mg protein^–1, a K_m of 0.059% (w/v) and an optimum pH of 5.5. Laminarinase from both species produced glucose and other short oligomers from the hydrolysis of laminarin. Endo-β-1,4-glucanase (EC 3.2.1.4) from G. natalis had a molecular mass of 52 kDa and an optimum pH of 4–7. It mainly hydrolysed β-1,4-glycosidic bonds, but was also capable of significant hydrolysis of β-1,3-glycosidic bonds. Two endo-β-1,4-glucanases, termed 1 and 2, with respective molecular masses of 53±3 and 52 kDa, were purified from C. destructor. Endo-β-1,4-glucanase 1 was only capable of hydrolysing β-1,4-glycosidic bonds and had an optimum pH of 5.5. Endo-β-1,4-glucanases from both species produced some glucose, cellobiose and other short oligomers from the hydrolysis of carboxymethyl cellulose.

3-dimensional characterization of membrane with nanoporous structure using TEM tomography and image analysis

The nanoporous structure of membrane varies in 3-dimensional (3-D) space and has remarkable influences on the filtration or desalination achieved, fouling potentials and therefore, the quality of yielded water. Knowledge of the 3-D nanoporous structure is thus vital to understanding and predicting its performance. A novel method by incorporating transmission electronic microtomography, image processing and 3-D reconstruction is introduced to characterize membranes with nano structures. The reconstruction algorithm allows for the visualization of 3-D nanoporous structure in a non-destructive way from any directions. This novel technique Ieads to in-depth understanding and accurate prediction of filtration performance.

An improved purification procedure for cyclosporine synthetase

We have developed expedient and reliable methods to isolate cyclosporin synthetase for in vitro biosynthesis of cyclosporins. We have examined enzyme purification strategies suited to large-scale processing and present a chromatographic sequence that serves as a pilot model for industrial scale preparation of cyclosporin synthetase from cyclosporin producing fungi. A chromatographic sequence consisting of ammonium sulfate precipitation → gel filtration → hydrophobic interaction chromatography → anion exchange chromatography, yielded an electrophoretically homogeneous cyclosporin synthetase preparation (Coomassie G-250 brilliant blue staining). Furthermore, a native polyacrylamide gel electrophoresis system was developed for the isolation of active cyclosporin synthetase enzyme from crude extracts of cyclosporin producing fungi. The environmental factors affecting enzyme stability and the continuity of the in vitro cyclosporin biosynthetic reaction-temperature, pH, and substrate depletion were assessed and manageable conditions have been defined for sustainable cyclosporin biosynthesis with enzyme isolates. Cyclosporin synthetase exhibited an optimal temperature range of 24–29 °C and a pH optimum of 7.6. The native enzyme displayed a pI of 5.7, as determined by isoelectric focusing. The industrial implementation of an in vitro biosynthetic approach could potentially prove useful for the production of important therapeutic cyclosporins which occur as only minor fermentation by-products.

An improved method for the purification of rat liver-type fatty acid binding protein from Escherichia coli

We have developed expedient and reliable methods to isolate cyclosporin synthetase for in vitro biosynthesis of cyclosporins. We have examined enzyme purification strategies suited to large-scale processing and present a chromatographic sequence that serves as a pilot model for industrial scale preparation of cyclosporin synthetase from cyclosporin producing fungi. A chromatographic sequence consisting of ammonium sulfate precipitation → gel filtration → hydrophobic interaction chromatography → anion exchange chromatography, yielded an electrophoretically homogeneous cyclosporin synthetase preparation (Coomassie G-250 brilliant blue staining). Furthermore, a native polyacrylamide gel electrophoresis system was developed for the isolation of active cyclosporin synthetase enzyme from crude extracts of cyclosporin producing fungi. The environmental factors affecting enzyme stability and the continuity of the in vitro cyclosporin biosynthetic reaction-temperature, pH, and substrate depletion were assessed and manageable conditions have been defined for sustainable cyclosporin biosynthesis with enzyme isolates. Cyclosporin synthetase exhibited an optimal temperature range of 24–29 °C and a pH optimum of 7.6. The native enzyme displayed a pI of 5.7, as determined by isoelectric focusing. The industrial implementation of an in vitro biosynthetic approach could potentially prove useful for the production of important therapeutic cyclosporins which occur as only minor fermentation by-products.

Copper and zinc mediated oligomerisation of Aß peptides

The accumulation of senile plaques composed primarily of aggregated amyloid β-peptide (Aβ), is the major characteristic of Alzheimer’s disease. Many studies correlate plaque accumulation and the presence of metal ions, particularly copper and zinc. The metal binding sites of the amyloid Aβ peptide of Alzheimer’s disease are located in the N-terminal region of the full-length peptide. In this work, the interactions with metals of a model peptide comprising the first 16 amino acid residues of the amyloid Aβ peptide, Aβ(1–16), were studied. The effect of Cu²⁺ and Zn²⁺ binding to Aβ(1–16) on peptide structure and oligomerisation are reported. The results of ESI-MS, gel filtration chromatography and NMR spectroscopy demonstrated formation of oligomeric complexes of the peptide in the presence of the metal ions and revealed the stoichiometry of Cu²⁺ and Zn²⁺ binding to Aβ(1–16), with Cu²⁺ showing a higher affinity for binding the peptide than Zn²⁺.