Volume Concentration Factor Research Articles

Stormwater treatment for removal of synthetic surfactants and petroleum products by reverse osmosis including subsequent concentrate utilization

The results of research are presented on new runoff and waste water treatment technologies based on the use of reverse osmosis (RO) systems equipped with specially designed open-channel membrane devices for treating water with a high suspended matter content. A characteristic feature of the technology is the utilization of the RO concentrate, which is discharged from the system together with the wet sludge and all contaminants rejected from water. The dependences of the concentration of pollutants in the filtrate and the membrane performance on the salinity of feed water and its volume concentration factor in the RO unit have been shown. The parameters of units operating with these types of wastewater have been determined. The effect of feed water salinity on the petrochemicals and detergents rejection efficiencies has been studied. A settleability prediction procedure, based on determination of the rate of membrane fouling with suspended solids as a function of their particle size, has been proposed to calculate the settling efficiency of flush water after hydraulic washing of membrane devices.

Purifying condensed water with ceramic ultrafiltration membranes

AbstractBackgroundHigh‐temperature condensed water has high recoverable value but it contains iron ions and oil, which need to be removed before use. Ceramic membranes with pore size between 4 and 50 nm were selected to purify the high‐temperature condensed water. The effects of operating parameters and membrane structure on the separation performance were investigated. Continuous concentration experiments were conducted to evaluate the influence of volume concentration factor (VCF) on membrane permeability.ResultsThe membrane exhibited high rejection of iron ions and oil. With increase of iron ions concentration, the permeate flux gradually decreased but the oil rejection increased. Oil concentration had no significant effect on the rejections of iron ions and oil. However, the permeate flux decreased with oil concentration owing to the formation of a thick fouling layer on the membrane surface. In the continuous concentration process, removal efficiencies of iron ion and oil were more than 99%, and the turbidity and oil concentration in permeate were less than 0.5 NTU and 0.5 mg L−1, respectively. The iron ion concentration in permeate was less than 0.3 mg L−1. These results meet the standards for boiler feedwater. Finally, the ceramic membrane was washed with 1 vol% HNO3 and then with 1 wt% NaOH. Pure water flux was recovered at >95%.ConclusionThis study showed the feasibility of purifying high‐temperature condensed water using a ceramic ultrafiltration membrane. © 2014 Society of Chemical Industry

Application of Positively Charged Composite Hollow-Fiber Nanofiltration Membranes for Dye Purification

A positively charged, composite, hollow-fiber nanofiltration (NF) membrane was fabricated by interfacial polymerization using polyethylenimine and trimesoyl chloride as reactive monomers. Rejection rates of different salts and dyes were measured by the NF membranes at various pH values. The effects of dye and salt concentrations on the membrane performance for dye purification were investigated. The dye and salt rejection rates would gradually decrease with an increase in the dye and salt concentrations. Then the influence of the volume concentration factor on dye purification during constant volume batch diafiltration process was studied. The results indicated that the higher of the concentration factor was, the better the concentration effect would be, and the less time would be needed.

A Compatible Membrane Process for Separation and Concentration of Pediocin PA-1 from Fermentation Broth

This work describes an effective combined ultrafiltration (UF)-nanofiltration (NF) membrane process for the separation and concentration of pediocin PA-1 from fermentation broth. Three polysulfone (PS) membranes with MWCOs of 5, 10, and 30 kDa were tested for ultrafiltration effectiveness. The 10 kDa membrane was selected because it displayed high permeability, good pediocin PA-1 recovery and reduced fouling. When the volume concentration factor (VCF) of UF reached 2.5, continuous diafiltration (DF) was carried out. The optimal diafiltration factor (DFF) was 1. The permeate obtained from UF was then concentrated by NF. When the VCF of NF reached 4.5, pediocin PA-1 recovery loss was only 10.5%. This two-stage membrane process improved the loading solutions by 4.5-fold, allowing up to 71.6% recovery of pediocin PA-1. After the membrane process, the NF retentate could be concentrated and subjected to preparative chromatography to obtain purified pediocin PA-1, or it could be dried to obtain a rich pediocin PA-1 preservative.

Incorporation of inorganic mercury (Hg2+) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg2+) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg2+ by four plankton fractions (picoplankton: 0.2–2.7μm; pico+nanoplankton: 0.2–20μm; microplankton: 20–50μm; and mesoplankton: 50–200μm) obtained from four Andean Patagonian lakes, using the radioisotope 197Hg2+. Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg2+ in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico+nanoplankton play a central role leading the incorporation of Hg2+ in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg2+ by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg2+ observed in all the plankton fractions.

Antioxidant Activity and Thermal Stability of Oleuropein and Related Phenolic Compounds of Olive Leaf Extract after Separation and Concentration by Salting-Out-Assisted Cloud Point Extraction.

A fast, clean, energy-saving, non-toxic method for the stabilization of the antioxidant activity and the improvement of the thermal stability of oleuropein and related phenolic compounds separated from olive leaf extract via salting-out-assisted cloud point extraction (CPE) was developed using Tween 80. The process was based on the decrease of the solubility of polyphenols and the lowering of the cloud point temperature of Tween 80 due to the presence of elevated amounts of sulfates (salting-out) and the separation from the bulk solution with centrifugation. The optimum conditions were chosen based on polyphenols recovery (%), phase volume ratio (Vs/Vw) and concentration factor (Fc). The maximum recovery of polyphenols was in total 95.9%; Vs/Vw was 0.075 and Fc was 15 at the following conditions: pH 2.6, ambient temperature (25 °C), 4% Tween 80 (w/v), 35% Na2SO4 (w/v) and a settling time of 5 min. The total recovery of oleuropein, hydroxytyrosol, luteolin-7-O-glucoside, verbascoside and apigenin-7-O-glucoside, at optimum conditions, was 99.8%, 93.0%, 87.6%, 99.3% and 100.0%, respectively. Polyphenolic compounds entrapped in the surfactant-rich phase (Vs) showed higher thermal stability (activation energy (Ea) 23.8 kJ/mol) compared to non-entrapped ones (Ea 76.5 kJ/mol). The antioxidant activity of separated polyphenols remained unaffected as determined by the 1,1-diphenyl-2-picrylhydrazyl method.

Studies on the separation of proteins and lactose from casein whey by cross-flow ultrafiltration

A novel strategy has been developed for separation of individual whey protein fractions and lactose from casein whey by a cascade of different molecular weight cut-off (MWCO) cross-flow ultrafiltration (UF) membranes. Centrifugation (166.67 r.p.s., 277 K, 1800 s) followed by microfiltration (MWCO: 0.45 × 10−6 m) were employed for separation of fat molecules and suspended solids from casein whey. Immunoglobulins, such as IgG, IgA, and IgM were separated as retentate of 100 kg mol−1 UF membrane; bovin serum albumin, lactoperoxidase, and lactoferrin were separated as retentate of 50 kg mol−1 UF membrane; lactose were separated by 5 kg mol−1 UF membrane as permeate, and major proteins like β-lactoglobulin (molecular weight 18.3 kg mol−1) and α-lactalbumin (molecular weight 14.2 kg mol−1) were separated by proper control of pH. At pH 5.4 the most dominant whey protein, β-lactoglobulin (isoelectric point 5.2–5.4), formed dimer which was found to have immense effect on the separation characteristics. Hydrodynamic studies were conducted under different trans-membrane pressures (TMPs), 0.686–2.942 bar using four-stages of discontinuous diafiltration (DD) with constant volume concentration factor (VCF 2). In all cases highly purified proteins were obtained at the 3rd stage of DD process under an optimum TMP of 2.06 bar.

Concentration and Desalination of Protein Derived from Tuna Cooking Juice by Nanofiltration

Tuna cooking juice is a co-product of tuna canning industry. It riches in protein, currently used for production of feed meal as well as protein hydrolysate. The finish products are usually in the form of concentrate, produced by evaporation process. However, evaporation is energy consumable process and the salt content level of the concentrate is often over the standard, thus required additional process for lowering salt content e.g. crystallization. The use of membrane technology, therefore, is of interest, since it required less energy and footprint compared with evaporation and is also able to reduce salt content of the concentrate. The aim of this study were to employ and select the membrane filtration process, and optimize the operating condition for protein concentration and desalination of tuna cooking juice. The results indicated that nanofiltration (NF) was more suitable than the ultrafiltration (UF) process, regarding the ability in protein recovery and desalination. The NF performance was evaluated in terms of permeation flux and protein and salt retentions. The protein and salt rejections of NF were 96 % and 5 %, respectively. The permeate flux(J) increased as transmembrane pressure (TMP) or cross flow rate (CFR) increased and the highest flux was obtained at TMP of 10 bar and CFR of 800 L/h. Operating with batch mode, the permeate flux was found to decrease as protein concentration increased, and at volume concentration factor about 4, the protein concentration about 10% while salt removal was aproximately 70 % of the initial value. This work clearly showed that NF was successfully employed for concentration and desalination of protein derived from tuna cooking juice.

A comparative study of microfiltration and ultrafiltration for algae harvesting

The present work deals with the filtration and concentration of algae (Chlorella) from a diluted culture medium using six commercial microfiltration membranes (MFP2, MFP5 and MFP8 with different pore sizes) and ultrafiltration membranes (FS40PP, FS61PP and ETNA10PP with different Molecular Weight Cut-Off (MWCO)). The effects of the operating conditions, e.g. feed solution temperature, TMP (transmembrane pressure), VCF (volume concentration factor) and cross-flow velocity on the filtration performance were investigated. The results showed that permeate fluxes increased with the increase in feed solution temperature, and the fluxes were probably limited by released extracellular polymeric substances (EPS) at higher temperatures. The permeate fluxes increased slowly with increasing TMP up to a certain limit, and after that the fluxes were stable or even decreased. The higher cross-flow velocity can significantly decrease particles accumulating on the surface of membrane, and thus leading to higher permeate flux. Although ETNA10PP exhibited much less fouling than other membranes, the permeate flux of this membrane was not higher than other membranes most likely due to the fact that this membrane is the ‘tightest’ membrane with MWCO 10,000. The performance of UF and MF membranes was compared for this application. The interesting finding of our work is that microfiltration and ultrafiltration showed very similar performance in terms of permeate flux under the same operation conditions at low TMP.

Purification and Characterization of β-Galactosidase Synthesized from Bacillus safensis (JUCHE 1)

In the present investigation, the purification of β-galactosidase synthesized from Bacillus safensis (JUCHE 1), a new strain isolated from casein whey, has been considered. Broth harvested after 28 h (100.8 × 103 s) was first centrifuged, and the sedimented cell pellet was sonicated to isolate intracellular β-galactosidase. After sonication, the intracellular fluid was subjected to microfiltration (MF) (0.2 × 10–6 m) and ultrafiltration (UF) (300 kg mol–1) in series using a flat-sheet poly(ether sulfone) (PES) membrane in a novel rotating-disk membrane module. In the present investigation, four-stage discontinuous diafiltration (DD) at a constant volume concentration factor (VCF = 2) was carried out. Hydrodynamic studies were conducted to determine the appropriate stirrer speed, transmembrane pressure (TMP), and membrane rotation speed. Finally, β-galactosidase was purified based on the principle of salting-out upon addition of 40% (w/v) ammonium sulfate, followed by dialysis using a 1 kg mol–1 membrane. ...

Concentration of ammonium diuranate effluent by reverse osmosis and forward osmosis membrane processes

In this study, both reverse osmosis (RO) and forward osmosis (FO) experiments are conducted to concentrate simulated inactive ammonium diuranate (ADU) filtered effluent solution (by mixing uranyl nitrate and ammonium nitrate) using indigenously developed cellulose acetate blend (CAB) and thin-film composite polyamide (TFCP) membranes. Both the membranes are prepared and characterized in terms of pure water permeability and solute rejection for 2000 ppm NaCl feed, water contact angle and surface average roughness. Subsequently, testing of volume reduction and concentration of simulated ADU effluent solution are carried out using custom made RO and FO testing systems. It is found that in RO process, the performance in terms of volume reduction factor and concentration factor with respect to uranium for both CAB and TFCP membranes are comparable but the CAB membranes show better performance than the TFCP membranes in FO modes. The concentration of ammonium nitrate is less in RO concentrate than in the FO concentrates. Similar experiments with the feed solution having different concentration of uranium (1–20 ppm) with same concentration of ammonium nitrate show that in FO, almost no leaching of uranium is found to the draw solution side but in RO, some of the uranium starts passing to the permeate side, particularly at lower concentration of uranium in the feed.

Dynamic cross-flow filtration of oilfield produced water by rotating ceramic filter discs

The purpose of this research paper is to assess the effects of the process parameters—membrane rotational speed (1,200, 1,500 and 1,800 rpm), volume concentration factor (VCF) and feed characteristics—in terms of oil and total organic carbon (TOC) separation capability, permeability and permeate quality. For this, a series of membrane filtration experiments were carried out systematically using rotating ceramic filter discs in a fed-batch operating mode. The variation of membrane rotational speed was found to minimize the membrane fouling in a significant amount. High oil (>99%) and TOC rejection (>98%) was achieved with both microfiltration (MF) and ultrafiltration (UF) membranes, independent of the rotational speed and the feed concentration The experimental results are presented for the dynamic cross-flow MF (0.2-μm pores) and UF (7-nm pores) of oilfield produced water as well as oily model solutions (OMS).

Recovery of Tungsten (VI) from Aqueous Solutions by Complexation-ultrafiltration Process with the Help of Polyquaternium

Polyquaternium-6 (PQ6) as the water-soluble polymer was used for complexing the anion forms of tungsten (VI) before ultrafiltration. Tungsten (VI)-PQ6 complex was retained by polysulfone hollow fiber ultrafiltration membrane in the complexation-ultrafiltration process. Effects of various operating parameters such as polymer metal ratio(PMR), pH and chloride ion concentration on permeate flux (J) and tungsten rejection coefficient (R) were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of regenerated polymer was carried out. In the process of concentration, J declines slowly and R is about 1 at PMR of 3 and pH of 7. Tungsten concentration in the retentate increases linearly with volume concentration factor. Tungsten is concentrated efficiently with the membrane. The concentrated retentate was used further for the decomplexation. It takes about 6 min to reach the decomplexation equilibrium at chloride ion concentration of 50 mgL−1. The decomplexation percentage of tungsten (VI)-PQ6 complex reaches 56.1%. In the diafiltration process, tungsten (VI) can be extracted effectively by using 50 mgL−1 chloride ion solution, and the purification of the regenerated PQ6 is acceptably satisfactory. The regenerated PQ6 was used to bind tungsten (VI) at various pH values. The binding capacity of the regenerated PQ6 is close to that of fresh PQ6, and the recovery percentage of binding capacity is higher than 90%.

Dissolved organic matter reduces algal accumulation of methylmercury

Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 × 10(4) , and the average VCF (from 10 to 72 h) over all experiments was 12.6 × 10(4) . At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 µM L-cysteine resulted in the largest drop in VCFs, to 0.28 × 10(4) . Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

Harvesting of Chlorella sp. using hollow fiber ultrafiltration

The suitability of the application of ultrafiltration (UF) to harvest Chlorella sp. from the culture medium was examined. We investigated the effects of two improved UF system, forward air-water flushing and backwash with permeate, on the concentration process. Backwash with permeate was selected as an optimization of the improved UF system, which was more effective for permeate flux recovery. Moreover, the hollow fiber UF system by adding periodical backwash with permeate was examined for Chlorella sp. harvesting. It was found that Chlorella sp. could be concentrated with high recovery in a lab-scale experiment. An overall algal biomass recovery of above 90% was achieved when the volume concentration factor was 10. For an original biomass of 1.3 ± 0.05 g/L, 1 min backwash followed by 20 min forward concentrating was more effective, which resulted in a recovery of 94% and a high average flux of 30.3 L/m(2)/h. In addition, the algal recovery was highly correlated to the volume concentration factor and the initial biomass. A high concentration factor or a high initial biomass resulted in a low biomass recovery.

Comparison of dead-end ultrafiltration behaviour and filtrate quality of sugar beet juices obtained by conventional and “cold” PEF-assisted diffusion

This work is devoted to ultrafiltration of sugar beet juices obtained by conventional high temperature diffusion and novel pulsed electric field (PEF) assisted low temperature diffusion. Filtration experiments were carried out in the concentration mode (up to the final volume concentration factor 7.5) using a batch dead-end filtration cell and hydrophilic polyethersulfone membranes with nominal molecular weight cut-offs (MWCO) of 10, 30 and 100 kDa. Two types of filtration experiments were carried out: without stirring and under constant stirring of feed juice. The transmembrane pressure was within the range 0.5–3.7 bar. The influence of filtration conditions (transmembrane pressure, membrane MWCO and stirring) on filtration rate, filtration mechanism and filtrate quality (purity and coloration) were studied and the results for juices obtained by conventional diffusion and by PEF-assisted diffusion were compared.

Experimental studies on extraction of cobalt ions from dilute aqueous solutions by using complexation-ultrafiltration process

The extraction of cobalt ions from dilute aqueous solutions was investigated by ultrafiltration with the help of poly(acrylic acid) sodium salt (PAASS). Polysulfone and polyethersulfone hollow fiber ultrafiltration membranes were employed in this process. The kinetics of complexation reaction was studied for PAASS with Co2+. Results showed that, under a large excess of PAASS, it takes 65, 55 and 40 min at pH 5, 6 and 7, respectively, to get the equilibrium of complexation. The reaction kinetics can be described by a pseudo-first-order equation. Then, the effects of various parameters on the extraction of Co2+ were examined in detail. Results indicated that loading ratio, pH value and low-molecular competitive complexing agent affect significantly cobalt rejection coefficient R. Furthermore, a concentration experiment was carried out at pH 7. With increasing volume concentration factor, membrane flux declines slowly, and R value is always about 1. The concentrated retentate was used further for a decomplexation experiment. The decomplexation ratio of cobalt-PAASS complex reaches as high as 90.1%. After the decomplexation step, a diafiltration experiment was performed at pH 2.5. Cobalt ions can be extracted satisfactorily from the retentate, and a purified PAASS is obtained.

Scavenging and retention of bismuth by marine plankton and biogenic particles

We did radiotracer experiments using 207Bi to quantify the bioavailability, accumulation, and retention of bismuth in marine plankton and biogenic detritus. The accumulation of 207Bi by two species of phytoplankton (Dunaliella tertiolecta and Emiliana huxleyi) was very rapid, approaching steady state after ~1 d. Emiliana cells without coccoliths reached a volume concentration factor (VCF) roughly twice that attained by cells with coccoliths. VCFs were 5 × 105 for Dunaliella and (4–9) × 106 for Emiliana after exposure for approximately 5 d. The radioactivity associated with Dunaliella was released with a biological half‐time of 3–5 d. Copepods (Anomalocera patersoni and Acartia species) grazing radiolabeled Dunaliella assimilated ~4% of the ingested 207Bi. Unassimilated radioactivity, voided in fecal pellets, was lost from pellets relatively slowly (half‐times of 26 d for Anomalocera and 58 d for Acartia). These release rates were similar to copepod fecal pellets that had scavenged 207Bi directly from water. Scavenging of bismuth from water by fecal pellets was considerable and extremely rapid, and uptake rates were similar to those of various size fractions of marine snow collected in a sediment trap. Release of scavenged 207Bi from the fresh fecal pellets was relatively slow, and very little release of radionuclide from the different size fractions of marine snow was observed. The biogeochemical behavior of bismuth in the marine environment closely resembles that of other particle‐reactive uranium‐thorium (U–Th) series and transuranic elements.

Cross-Flow Microfiltration of Oily Water using a Ceramic Membrane: Flux Decline and Oil Adsorption

The microfiltration of oil-water emulsion solutions through a ceramic membrane was investigated in this study. A surfactant-free dispersed oil-water emulsion in the range of 0.2–2% kerosene was fed into a tubular ceramic membrane module as a turbulent flow. The optimal trans-membrane pressure was determined. For oily water containing less than 0.5% kerosene content, the steady-state permeate flux of 3.36 × 10−5 m3/m2 s bar (121 L/m2 h bar) could be achieved; the oil retention was as high as 99.5% at a volume concentration factor of 4. The solute diffusion coefficient was 9.765 × 10−10 m2/s and the mass transfer coefficient was 2.687 × 10−5 m/s in this system. The resistance-in-series model was applied to describe the flux decline and the individual resistance from the membrane, oil adsorption, gel formation, and concentration polarization were calculated. The results indicated that the oil (solute) adsorption on the membrane surface was the major source of resistance. The scanning electron micrograph indicated oil adsorption on the membrane surface. As the oil content in the feed increased, the gel formation and the concentration polarization also played a role, contributing to flow resistance and causing flux decline. Furthermore, increasing the operating temperature enhanced the flux and the activation energy was determined as 2.918 kJ/mol. A reversible model of dispersed oil adsorption into the gel state was used to explain the flux decline during the filtration process.

Ultrafiltration, chemical and biological oxidation as process combination for the treatment of municipal landfill leachate

A hybrid treatment process was evaluated to reduce the organic load of leachate generated in a former landfill. The leachate, regardless of the time the waste was deposited (“leachate A” has its source in young waste and “leachate B” has its source in old waste), presented high recalcitrance as evidenced by high pH values, salinity (chlorides), COD/BOD5 ratio and concentration of metals. The fractionation of leachate through filtration using micro- and ultrafiltration membranes revealed that leachate B presented a higher proportion of soluble organic compounds, and its aging led to the decomposition of macromolecules. The ultrafiltration of leachate B with a 20 kDa cut-off membrane to a volume concentration factor of 3.2 and transmembrane pressure close to 1.0 bar resulted in flows of 15 to 20 L.m-2.h-1 and removal efficiencies of 76% and 79% for COD and color, respectively. The concentrate, when treated with Fenton reagent at pH 4.0, 0.05 mol H2O2.L-1 and 200 mg Fe2+.L-1, presented its TOC content reduce...