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Sulfonated polysulfone (SPSF) flat ultrafiltration membranes were successfully prepared by immersion precipitation phase inversion method. N-Methyl pyrrolidone was used as a solvent, and polyvinylpyrrolidone (PVP) was used as a polymeric additive in the casting solution. The effects of casting solution formulation and preparation conditions on membrane structure and properties were investigated in present study, and the morphology of the membranes was analyzed by scanning electron microscopy. The results indicated that the performances of SPSF membranes made by chemical modification were better than polysulfone membrane. The SPSF concentration played a vital role in restricting the pure water flux (PWF), promoting the rejection coefficient, and improving the hydrophilicity. A maximum PWF and minimum egg albumin rejection coefficient were obtained when the PVP content was 10%. When the coagulation bath temperature was set to 25°C, the PWF reached 480 L x [m.sup.-2] x [h.sup.-1] and the ovalbumin rejection coefficient reached 92%. Longer evaporation times improved the PWF. Specifically, when the evaporation time was 70 s, the comprehensive performance was good., INTRODUCTION The immersion precipitation phase inversion method is one of the most important processes for preparing asymmetric polymeric membranes such as those used in nanofiltration, reverse osmosis, ultrafiltration, microfiltration, and [...]

A facile method to prepare microfiltration membrane was proposed in this study. The method involved the interfacial polymerization of 1,6-hexamethylene diamine and adipoyl chloride to form polyamide (nylon 6,6) on the polyacrylonitrile (PAN) electrospun nanofi-brous (ENF) membranes as the scaffold. The effects of process parameters, such as monomer concentrations, monomer coating sequence, reaction time and number of reaction cycles, on the amount of polyamide that formed were investigated. It was found that polyamide that formed by interfacial polymerization existed not only on the surface but also in the interior of the ENF membranes. A mechanism was proposed to explain the phenomenon. The pore sizes of the formed poly-amide/PAN ENF membranes, ranging from 0.13 to 4.88 pm, can be controlled by the number of reaction cycles. These polyamide/PAN ENF membranes also exhibited enhanced tensile strength. POLYM. ENG. SCI., 54:430-437, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION Filtration by polymeric membranes is an important separation and purification process in various industries. Depending on the sizes of filtered particles, these membranes can be used for reverse osmosis [...]

A new methodology for nanoscopic molecular filtering was developed using a substrate with a periodic array of metallic nanogates with various widths between 75 and 500 nm. A self-spreading lipid bilayer was employed as the molecular transport and filtering medium. Dye-labeled molecules doped in the self-spreading lipid bilayer were filtered after the spreading less than a few tens of micrometers on the nanogate array. Quantitative analysis of the spreading dynamics suggests that the filtering effect originates from the formation of the chemical potential barrier at the nanogate region, which is believed to be due to structural change such as compression imposed on the spreading lipid bilayer at the gate. A highly localized chemical potential barrier affects the ability of the doped dye-labeled molecules to penetrate the gate. The use of the self-spreading lipid bilayer allows molecular transportation without the use of any external field such as an electric field as is used in electrophoresis. The present system could be applied micro--and nanoscopic device technologies as it provides a completely nonbiased filtering methodology.

The filtration performance of a geotextile is controlled by its pore opening size distribution (PSD). Current methods for determining PSD are mostly indirect and contain inherent disadvantages. Recent technological advancements in image analysis offer great potential for a more accurate and direct way of determining the PSD of nonwoven geotextiles. A new and accurate method of image analysis for PSD determination of nonwoven geotextiles is presented in this paper. The image analysis method was developed using various mathematical morphology algorithms to provide a complete PSD curve for each geotextile. The two characteristic pore opening sizes, [O.sub.95] and [O.sub.50], were determined from image analysis and were compared to the results from laboratory tests, analytical equations, as well as manufacturer's reported apparent opening sizes (AOS). The image-based 095 pore opening size of various geotextiles was comparable to the manufacturer's reported AOS as well as to those determined from the laboratory dry sieving test. However, the measured [O.sub.50] pore opening size was lower than the one determined using the analytical equations developed by two previous researchers. Overall, the image analysis method presented provides a unique and accurate method that can measure fiber thickness and pore opening sizes in a cross-sectional image of a woven geotextile. DOI: 10.1061/(ASCE)0887-3801(2002) 16:4(280) CE Database keywords: Imaging techniques; Digital techniques; Geosynthetics; Pore size distribution; Filtration.

The benefits of high-throughput bioanalysis within the pharmaceutical industry are well established. One of the most significant bottlenecks in bioanalysis is transferring in vivo-generated study samples from their collection tubes during sample preparation and extraction. In most cases, the plasma samples must be stored frozen prior to analysis, and the freeze/thaw (F/T) process introduces thrombin clots that are capable of plugging pipets and automated liquid-transfer systems. A new approach to dealing with this problem involves the use of Ansys Captiva 96-well 20-[micro] m polypropylene filter plates to collect, store frozen, and filter plasma samples prior to bioanalysis. The samples are collected from the test subjects, and the corresponding plasma samples are placed directly into the wells of the filter plate. Two Duoseal (patent pending) covers are used to seal the top and bottom of the plate, and the plate is stored at down to -70 [degrees] C. Prior to sample analysis, the seals are removed and the plate is placed in a 96-well SPE manifold. As the plasma thaws, it passes (by gravity or mild vacuum) through the polypropylene filter into a 96-well collection plate. A multichannel pipet or automated liquid-transfer system is used to transfer sample aliquots without fear of plugging. A significant advantage of this approach is that, unlike other methods, issues related to incomplete pipetting are virtually eliminated. The entire process is rapid since thawing and filtering take place simultaneously, and if a second F/T cycle is required for reanalysis, it is not necessary to refilter the samples (additional clotting was not observed after three F/T cycles). This technique was tested using monkey, rat, and dog plasma and sodium heparin and EDTA anticoagulants. To assess the possibility of nonspecific binding to the polypropylene filter, a variety of drug candidates from diverse drug classes were studied. Validation data generated for two Lilly compounds from distinct classes, before and after filtering, are presented in this paper as practical examples of this technique. While LC/MS/MS is the primary method of bioanalysis in our laboratory, the technique presented in this paper is applicable to other forms of detection as well.

A novel water purification system that uses a continuous superconducting magnet in filtering phytoplankton has been designed and constructed. The system incorporates a twin-type superconducting magnet with a helium cooler, a reciprocating main magnetic filter and a rotating magnetic sub-filter. The reciprocating and rotating assemblies allow the magnetic filters to alternate between filtration and the backwashing cycle. The system was able to remove more than 93% of phytoplankton from lake water at flow rates of 400 cubic meter per day.

A pilot-scale compost biofiltration system was operated at a gasoline soil vapor extraction site in Hayward, Calif. for one year. The media was composed of equal volumes of compost and perlite, a bulking agent. Supplements added included nitrogen (as KN[O.sub.3]), a gasoline degrading microbial inoculum, buffer (crushed oyster shell), and water. The biofiltration system was composed of four identical units with outside dimensions of 1.2 x 1.2 x 1.2 m (4 x 4 x 4 ft) operated in an up-flow mode. The units were configured in parallel during the first eight months and then reconfigured to two parallel systems of two units in series. Air flux values ranged from 0.29 to 1.0 [m.sup.3]/[m.sup.2] per min. Inlet total petroleum hydrocarbon ([TPH.sub.gas]) concentrations ranged from 310 to 2,700 mg/[m.sup.3]. The average empty bed contact time was 2.2 min. Following start-up, performance of the individual biofilters varied considerably for a seven-month period. The principal factor affecting performance appeared to be bed moisture content. Overall [TPH.sub.gas] removals reached 90% for short periods in one unit, and BTEX removals were typically above 90%. Drying resulted in channeling and loss of bed activity. Management of bed moisture content improved over the study period, and recovery of system performance was achieved without replacement of bed media. Overall TP[H.sub.gas] removals exceeded 90% during the final 50 days of the study.

A membrane bioreactor system that overcomes many of the limitations of conventional compost biofilters is described. The system utilizes microporous hydrophobic hollow fiber membranes for mass transfer of volatile organic compounds (VOCs) from the gas phase to a microbially active liquid phase. The reactor design provides a high biomass concentration, a method for wasting biomass, and a method for addition of pH buffers, nutrients, cometabolites, and/or other amendments. A theoretical model is developed, describing mass transfer and biodegradation in the membrane bioreactor. Reactor performance was determined in a laboratory scale membrane bioreactor over a range of gas loading rates using toluene as a model VOC. Toluene removal efficiency was greater than 98% at an inlet concentration of 100 [ppm.sub.v] and a gas residence time of less than 2 s. Factors controlling bioreactor performance were determined through both experiments and theoretical modeling to include: compound Henry's law constant, membrane specific surface area, gas and VOC loading rates, liquid phase turbulence, and biomass substrate utilization rate.

The work describes the aerobic biodegradation of volatile organic compound (VOC) mixtures from effluent air streams in laboratory-scale compost based biofilters. A rapid start-up of the system (3-5 d) was observed and 82% of the carbon in the influent pollutant (methyl ethyl ketone) was recovered as carbon dioxide in the exhaust air after this period. Biofilter performance and carbon dioxide production were also investigated during and after 0.5-1-h step inputs of 2-10 g [m.sup.-3] of hexane, acetone, 1-propanol, and/or methyl isobutyl ketone (MIBK) during steady methyl ethyl ketone (MEK) treatment. Carbon dioxide patterns suggest that pulsed pollutants were first sorbed onto the packing material and subsequently degraded within 2-5 h. Hexane was not sorbed, and thus not degraded to a significant extent. Little effect was observed of the step inputs on the overall MEK removal process, mainly because the reactors were operated well below MEK breakthrough loading. However, the analysis of MEK profiles within the biofilter bed showed that significant inhibition did indeed occur. An even more important inhibition was observed between 1-propanol, MIBK, and acetone, when such a mixture was injected into the reactor. Practical design of biofilters should consider the possibility of reduced performances due to the presence of multiple VOCs in the waste air stream.

The determination of transfer rate constants (k) and concentration partition coefficients ([k.sub.h]) is required for biofilter mathematical models. A bench-scale technique was developed and used to evaluate k and [k.sub.h] values for four different packing materials: (1) compost; (2) a mixture of compost and diatomaceous earth (DE); (3) Calgon granular activated carbon (GAC); and (4) Westates GAC. Two vapor phase contaminants were used: ethanol and carbon dioxide. Experimental results showed that this technique produced estimated [k.sub.h] values that were similar to both 'batch' and 'spike test' results, indicating the accuracy of the procedure. Calculated [k.sub.h] values for carbon dioxide were two orders of magnitude less than those for ethanol. The water content of the packing material strongly affects [k.sub.h] values. High water content increased [k.sub.h] values for ethanol and decreased [k.sub.h] values for carbon dioxide.

This paper reports the result of studies using two biotrickling filters (BTFs) with wood and plastic packings, respectively, for treatment of methylethylketone (MEK) in an air stream. Effects of packing material, specific surface area of the packings, volumetric loading of MEK, nutrient addition, and the recirculation rate of liquid on the MEK elimination capacity were tested. Results show that the elimination capacity of MEK in the BTF system can be evaluated on the basis of unit surface area of packing materials. Surface properties may not be a major concern in choosing a packing. Nutrient addition is essential for obtaining an efficient elimination of the influent contaminants to BTFs. For treating water-soluble contaminants, the liquid recirculation rate is a minor operation factor in the case of minute residual contaminants in the liquid. A high liquid recirculation rate should be avoided at such high level of contaminant loadings, since some contaminants remain in the liquid.

Biofiltration is a biological air pollution control technology for volatile organic compounds (VOCs). This paper summarizes the fundamentals, design and operation, and application of the process. Biofiltration has been demonstrated to be an effective technology for VOCs from many industries. Large and full-scale systems are in use in Europe and the United States. With proper design and operation, VOC removal efficiencies of 95-99% have been achieved. Important parameters for design and performance are empty-bed contact time, gas surface loading, mass loading, elimination capacity, and removal efficiency. Key design and operation factors include chemical and media properties, moisture, pH, temperature, nutrient availability, gas pretreatment, and variations in loading.

A field study on the treatment of volatile petroleum hydrocarbons (PHC) by biofiltration was conducted by the Petroleum Environmental Research Forum (PERF) between 1992 and 1994. Its objective was to assess the technical, regulatory, and economic feasibility of biofiltration for off-gases from petroleum processing and soil remediation equipment. It involved three small-scale biofilters provided by U.S. vendors, treating off-gas from two soil vapor extraction sites and a source of refinery wastewater. Comprehensive monitoring of biofilter operating parameters and performance was conducted. The results suggest that biofilters remove major petroleum hydrocarbon classes to strongly varying degrees. Typically more than 95% of aromatic compounds such as benzene, and odorous reduced sulfur compounds can be removed at residence times of one minute or less, while removal of more than 70% of light aliphatics will require residence times of several minutes, and will thus require correspondingly large filter volumes and higher capital expenditure. This indicates that off-gas composition and regulatory control objective will largely determine whether biofiltration is economically feasible for a given off-gas stream. The high percentage removal of aromatic hazardous air pollutants (HAP) and odors can generally be accomplished at comparatively short residence times (one minute or less) while the need for high-percentage removal, particularly of light aliphatics (< [C.sub.5]) will generally render biofiltration noncompetitive. Results from the field tests also showed that biofilter performance and operational reliability depend on the selection of filter material, the reliability of the moisture control system, and the level of fluctuation in PHC concentrations. This agrees with the findings from other full-scale biofilter projects. Finally, a preliminary economic comparison of biofilters and established control technologies suggested that biofiltration may, for a representative design case involving off-gas from a refinery wastewater treatment operation, offer considerable savings in total cost of air pollution control for petroleum hydrocarbon streams if regulations require the control of aromatic HAP or odors.

The special issue on biofiltration discusses topics relevant to biofilter engineering ranging from fundamental processes to improving biofilter designs and operating conditions. Biofiltration was first used in controlling odors and the original biofilters merely consisted of perforated pipes laid over soil beds in outdoor trenches. There are currently over 500 biofilters in use in Europe for treating odors at coffee-roasting plants, meat-packing plants and in other manufacturing plants. Biofilters, biotrickling filters and biological scrubbers are the three most popular designs because they can be designed and operated inexpensively.

Bigneat Containment Technology offers enclosures that provide a sterile environment for robotics systems with laminar flow protection for operators. The cabinets are accessed by hinged or sliding doors. Two HEPA [...]