Coarse Filtration Research Articles

Comparative evaluation of different pre-treatment alternatives for granular media filters treating greywater and their ranking using analytical hierarchy process.

In this study, the performance of four different pre-treatment alternatives for granular media filtration, namely, settling, aeration, coarse media filtration and chemical coagulation were compared experimentally. Further, analytical hierarchy process (AHP) was used to compare their performance based on economic, environmental, technical and performance criteria. Performance of settling and aeration were evaluated up to 24 h duration. The coarse media filter was intermittently operated with 10 L of greywater in downflow mode while alum was used for chemical coagulation. Experimental results showed that settling up to 6 h did not show significant removal of different pollutants whereas 24 h settling resulted in moderate removal of turbidity and organic content but was not efficient in the removal of nutrients and faecal coliforms. Chemical coagulation reduced 93, 66, 48 and 97% of turbidity, COD, NH4-N and faecal coliforms, respectively from greywater but resulted in excessive sludge generation and is difficult to adopt on-site and requires skilled supervision. Coarse filtration of greywater resulted in 61, 41, 36 and 35% removal of turbidity, COD, PO4-P and faecal coliforms, respectively. Considering different criteria AHP gave coarse filtration as the best pre-treatment option to the granular media filters treating greywater.

Treatment of anaerobically digested pig manure by applying membrane processes for nutrient recovery and antibiotics removal.

A combination of membrane processes was applied to treat the digestate produced after the anaerobic treatment of pig manure in a biogas plant, aiming towards the recovery of nutrients and effective water treatment for potential reuse. Initially, coarse filtration (sieving and microfiltration) was used to remove particles larger than 1 µm, followed by ultrafiltration, to reduce the suspended solids concentrations below 1g/L. Subsequently, selective electrodialysis is employed to recover the main nutrient ions, primarily ammonium and potassium. The ion-depleted digestate is then fed to a reverse osmosis unit, where clean water was recovered, yielding a by-product (concentrate) stream enriched in phosphates and organics content. The presence of antibiotics and the concentrations of heavy metals were monitored during all treatment stages to assess their behavior/removal in the various membrane processes. The results indicate that almost 51% of the digestate could be recovered as water free from ions and antibiotics, suitable for reuse in the biogas plant for process needs and irrigation purposes. The selective electrodialysis process can recover 51% of initial NH4+ content (corresponding to 96% of the electrodialysis feed), while the remainder largely ended up in the ultrafiltration concentrate. A similar behavior was observed for the case of K+, while approximately 68% of the phosphates content was retained by the coarse filtration process, with another 24% remaining in the ultrafiltration concentrate and the remaining 8% in the reverse osmosis concentrate. Most of the antibiotics and heavy metals were retained by the coarse and ultrafiltration steps, with smaller amounts detected in the reverse osmosis concentrate.

Impact of technological operations on oxygen consumption during wine production

AbstractOxygen plays a crucial role in all stages of wine production. The aim of this study was to quantify dissolved oxygen in filtered wines trained on fine lees during different technological operations such as racking, coarse filtration, stabilisation of thermolabile proteins, and sterile filtration and bottling. The most significant oxygenation of wine occurs during filtration (1.9–3.57 mg L−1) and during bottling (2.99–4.12 mg L−1). At the same time, oxygen affects the phenolic composition, antioxidant activity and sulphur dioxide.Understanding and being able to use oxygen correctly during wine production can lead to a reduction in the doses of sulphur dioxide used. It has been shown that wines trained on fine lees are more able to withstand oxygen and, therefore, the sulphur dioxide doses can be reduced substantially. The experiment, in which two different winemaking technologies were observed, was carried out on the Welschriesling variety using both stainless steel tanks and oak barrels.

COMPARISON BETWEEN CENTRIFUGATION, COARSE FILTRATION AND MICROFILTRATION TECHNIQUES TO PREPARE AUTOLOGOUS BLOOD TRANSFUSION

In case of a bleeding patient, centrifugal cell salvage washing technique for autologous blood preparation is a preferred medical treatment in order to retain lost RBCs without contaminants. Although highly efficient in collection and washing shed blood, centrifugal cell salvage technology is costly and often unpractical or unavailable, especially in middle or low income countries, creating a need for more cost-effective and practical technologies. This study assessed two innovative filter devices as an alternative for the centrifugal cell salvage technology; a coarse collection filter device (Hemafuse) and a microfiltration device (HemoClear). Both devices were recently introduced in the Kenyan and European markets, respectively. Their accessible design could make these devices valuable additions to the current cell salvage technologies. We compared the effectiveness of these filtration technologies to remove plasma constituents and recover and concentrate the cellular components with a centrifugal device (autoLog®). Diluted whole blood was processed with each technology according to their manufacturer's instructions. The centrifugal technology confirmed its efficacy to remove potentially harmful solutes and capture red blood cells. The microfiltration technology (HemoClear) reached comparable levels of removal of solutes as the centrifugal technology, with a potential advantage over centrifugal technology in the ability to also recover platelets. The coarse filtration technology (Hemafuse) had no washing capacity but like the microfiltration technology, has the advantage of recovering platelets.

Comparison of Washing Efficiency and Recovery of Blood Cells Between Centrifugation, Coarse Filtration and Microfiltration Techniques to Prepare Autologous Blood for Transfusion.

PurposeCell salvage is the process by which blood lost in surgery is collected and washed or filtered to produce autologous blood for re-transfusion to the patient. Cell salvage aims to reduce the need for donor blood. Centrifugal cell salvage washing technique is a preferred medical treatment in order to retain lost red blood cells (RBCs) without contaminants. Although this technology very efficiently collects and washes shed blood, it is costly and often impractical or unavailable, especially in middle- or low-income countries. This study assessed two innovative filter devices as an alternative to centrifugal cell salvage technology: a coarse collection filter device (Hemafuse) and a microfiltration device (HemoClear). In contrast to centrifugal technology, both filter devices do not require electricity, nor costly equipment and extensive training. We compared the effectiveness of these filtration technologies to remove plasma constituents and recover and concentrate the cellular components with centrifugal technology (autoLog® device).MethodsWhole blood was processed with each technology according to the device manufacturer’s instructions. Before and after processing, the blood products were analyzed for supernatant solutes and cellular composition.ResultsThe centrifugal technology confirmed its efficacy to remove potentially harmful solutes and capture red blood cells. The microfiltration technology (HemoClear) reached comparable levels of removal of solutes, with a potential advantage over centrifugal technology in the ability to also recover platelets. The coarse filtration technology (Hemafuse) had no washing capacity but, like the microfiltration technology, has the advantage of recovering platelets.ConclusionInnovative filtration devices represent an alternative to centrifugal technology in the preparation of autologous blood for reinfusion. The HemoClear technology for the first time enables the recovery of washed platelets and red blood cells. Clinical trials will have to be performed to investigate the clinical value of this new autologous blood product.

Using texture analysis in the development of a potential radiomic signature for early identification of hepatic metastasis in colorectal cancer

BackgroundRadiomics allows information not readily available to the naked eye to be extracted from high resolution imaging modalities such as CT. Identifying that a cancer has already metastasised at the time of presentation through a radiomic signature will affect the treatment pathway. The ability to recognise the existence of metastases earlier will have a significant impact on the survival outcomes. AimTo create a novel radiomic signature using textural analysis in the evaluation of synchronous liver metastases in colorectal cancer. MethodsCT images at baseline and subsequent surveillance over a 5-year period of patients with colorectal cancer were processed using textural analysis software. Comparison was made between those patients who developed liver metastases and those that remained disease free to detect differences in the ‘texture’ of the liver. ResultsA total of 24 patients were divided into two matched groups for comparison. Significant differences between the two groups scores when using the textural analysis programme were found on coarse filtration (p = 0.044). Patients that went on to develop metastases an average of 18 months after presentation had higher levels of hepatic heterogeneity on CT. ConclusionThis initial study demonstrates the potential of using a textural analysis programme to build a radiomic signature to predict the development of hepatic metastases in rectal cancer patients otherwise thought to have clear staging CT scans at time of presentation.

Investigation of the quality of water in the process of its purification using ultrafiltration by the method of differential scanning calorimetry

The increased interest in ultrafiltration technology in the last decade is caused by the search for new purification methods that allow obtaining high-quality drinking water that meets modern regulatory requirements. Modern water purification schemes use an ultrafiltration unit before reverse osmosis in softening, desalination and demineralization of water for food production. The pore size of ultrafiltration membranes ranges from 5 nm to 0.05-0.1 microns. Using ultrafiltration instead of the traditional water treatment scheme, makes it possible to obtain water with a low content of suspended and colloidal substances, increase the productivity and serviceability of reverse osmosis membranes. The water treatment scheme may contain the following modules: coarse filter; ultrafiltration unit, buffer tank; mixer; water container; reverse osmosis installation; pumps. The method of differential scanning microscopy is used to assess the quality of water during its purification. Water samples were cooled with liquid nitrogen to -30 ? and then heated to 30 ?. Crystals melting peaks were recorded on the DSC curves, and the thermal effect was calculated. During the water purification process, the value of the thermal effect of frozen water samples melting declines (from 515.1 to 261.2 J / g), the value of the temperatures at the onset (from 0.7 to -0.13 ?) and at the peak of crystal melting (from 7.45 up to 4.27 ?). The difference between the heat effect data for water samples after coarse filtration and ultrafiltration is small, which indicates that the ultrafiltration unit allows cations and anions to pass through, which preserves the salt balance of water.

Chemical-Free Greywater Treatment Using Aeration, Sedimentation, Followed by Granular Activated Carbon Filter (GAC) -A Case Study of Baghdad city household

Greywater is a possible water source that can be improved for meeting the quality required for irrigation. Treatment of greywater can range from uncomplicated coarse filtration to advanced biological treatment. This article presents a simple design of a small scale greywater treatment plant, which is a series of physical and natural processes including screening, aeration, sedimentation, and filtration using granular activated carbon filter and differentiates its performance with sand filter. The performance of these units with the dual filter media of (activated carbon with sand) in treatment of greywater from Iraqi house in Baghdad city during 2019 and that collected from several points including washbasins, kitchen sink, bathrooms, and laundry, was recorded in terms of removal efficiency of particular pollutants like Turbidity 94%, chemical oxygen demand (COD) 93%, and oil 91%. Dual filter was the most effective filter for decreasing these pollutants, while sand indicates the lowest removal efficiency. In general, granular activated carbon media seemed to be the most proper medium to improve greywater quality for reaching the quality of irrigation within the terms of organic matter decrease. Accordingly, this technology may be reliable for greywater treatment in a residential area.

Process design of coal seam gas associated water treatment plants to facilitate beneficial reuse

This study used computer simulation to select appropriate process designs to make coal seam gas (CSG) associated water comply with beneficial reuse regulations. The hypothesis was that computational simulation may predict the unit operations required for treatment of CSG associated water over a wide range of salinities. AqMB software facilitated complete analysis of water treatment from initial storage pond to final pH and sodium adsorption ratio (SAR) adjustment. Three samples of CSG associated water ranging from 3650 to 22123 mg/L total dissolved solids content were evaluated. Common to each process design was a settling pond, coarse & fine filtration, softening, anti-scalant addition, and reverse osmosis. When the water hardness was very hard, then a lime softening system may be required. Both microfiltration and ultrafiltration were considered, and in both cases the level of suspended solids was reduced to close to zero. Sodium exchanged WAC resin removed the majority of alkaline earth ions and inhibited downstream scale formation. The presence of substantial alkalinity was addressed by use of acid exchanged WAC resin in combination with an air stripper. However, process economics indicated this option was not favourable. A two-stage Reverse Osmosis system not only recovered from ca. 74–79 % water with all CSG associated water types but also the water quality was compliant with beneficial reuse regulations. The computer predictions mirrored actual data from operating industry sites.

Water Recovery from Floor Cleaning Operations of Industrial or Public Areas: The Results of a Field Test

Water resources are increasingly under pressure because of human activities and economic development. Moreover, accelerated urbanization and the expansion of drinking water supply and sanitation systems contribute to this rising demand. The development of water reuse solutions is an urgent issue. This study presents a solution for the reuse of wastewaters generated from floor cleaning operations of industrial or public areas. A portable device containing a grid, for coarse filtration, and a 300-L reaction chamber to carry out the sequential processes of coagulation, flocculation and settling, was employed for a field test. In the field test the wastewater coming from the tank of a cleaning machine, used for floor cleaning in an industrial site, was treated and reused for the same purpose for a total of 110 times. The quality of the treated wastewater was monitored cycle after cycle and the results of the test demonstrated that the treated water was suitable to be reused for the same purpose, even after a large number of cycles, provided that a finishing treatment was eventually supplemented in order to reduce the residual concentration of organic substances. It was demonstrated that, under standard operating conditions, that is a wastewater with a total suspended solid (TSS) content of 800 mg/L, and on the grounds of the results found in the test, that is a TSS removal efficiency of 98% and a sludge total solid (TS) content of 6%, the whole volume of the cleaning machine tank was completely renewed with fresh water after 60 cycles. Eventually, the combination of treatment and reuse operations allowed to save approximately 18,000 L of fresh water over a series of 60 cleaning cycles. The proposed treatment allowed not only to save fresh water but even to reduce the cost of water usage by approximately 50%. In fact, thanks to this treatment, the cost of a single cubic meter of water decreased from approximately 6 €/m3, which included supply of fresh water and discharge to the public sewer, to approximately 3 €/m3.

Indoor air quality analysis of 8 mechanically ventilated residential buildings in northeast China based on long-term monitoring

In this study, 8 residential buildings with installed fresh air systems were selected to monitor indoor air quality. Data on temperature and concentrations of formaldehyde, VOC, CO2, and PM2.5 were collected. Phenol reagent spectrophotometry and GC–MS were used to test for the concentrations of formaldehyde and VOC on site. Indoor air quality sensors, window sensors, fresh air system sensors, and smart sockets were used for long-term monitoring online. The test results showed that the indoor air quality varied with seasonal characteristics. The concentrations of PM2.5, formaldehyde, and CO2 exceeded the national standard in winter, summer and transition seasons, respectively. The fresh air systems had obvious effect on reducing indoor concentrations of formaldehyde, VOC, and CO2. Fresh air systems reduced the concentration of formaldehyde by 52.4 % when in use. The TVOC concentration under closed condition was 0.641 mg/m3, and the annual average was 46.8 % of it.The CO2 concentration exceeded the national standard only during the early stage of heating, with an average concentration of 1133 ppm. However, only the medium and high-efficiency filtration fresh air systems significantly reduced PM2.5 concentration, and using air purifiers to assist in common coarse filtration was a worthwhile choice.

Electrostatically assisted air coarse filtration for energy efficient ambient particles removal: Long-term performance in real environment and influencing factors

Electrostatically assisted air (EAA) coarse filter can improve the particle filtration performance of low efficiency filters without increasing their pressure drop. In this study, we investigated the long-term single pass filtration efficiency for 0.3–10 μm ambient particles, pressure drop, PM2.5 collecting amount, and energy consumption of an EAA coarse filter during a 51-day operation period. We found that the efficiency of EAA coarse filter varied with average values of 87.6%–97.1% for 0.3–10 μm particles, respectively, while the pressure drop increased from 14.6 Pa to 63.1 Pa at face air velocity of 1 m/s. Using K-means clustering and principal components analysis methods, we discovered that before 33 days, the significant influencing factors of the efficiency for 0.3–0.5 μm particles included air temperature, air moisture content, 3–10 μm particle number concentration, and PM2.5 collecting amount. While after 33 days, only PM2.5 mass collecting amount has a significant negative correlation with the efficiency for 0.3–0.5 μm particles. The efficiency became relatively unsteady and the PM2.5 collecting amount reached 131 g/m2 after 33 days. The total energy consumption of EAA coarse filter rose more slowly as PM2.5 collecting amount increased when compared with that of a conventional electret filter (KAFPO78A4, Daikin Inc., Japan). We suggest the high efficiency EAA coarse filtration as an energy efficient method for ambient particle removal in the view of its long-term performance.

Improvement of 3D Power Line Extraction from Multiple Low-Cost UAV Imagery Using Wavelet Analysis.

Three-dimensional (3D) mapping of power lines is very important for power line inspection. Many remotely-sensed data products like light detection and ranging (LiDAR) have been already studied for power line surveys. More and more data are being obtained via photogrammetric measurements. This increases the need for the implementation of advanced processing techniques. In recent years, there have been several developments in visualisation techniques using UAV (unmanned aerial vehicle) platform photography. The most modern of such imaging systems have the ability to generate dense point clouds. However, image-based point cloud accuracy is very often various (unstable) and dependent on the radiometric quality of images and the efficiency of image processing algorithms. The main factor influencing the point cloud quality is noise. Such problems usually arise with data obtained via low-cost UAV platforms. Therefore, generated point clouds representing power lines are usually incomplete and noisy. To obtain a complete and accurate 3D model of power lines and towers, it is necessary to develop improved data processing algorithms. The experiment tested the algorithms on power lines with different voltages. This paper presents the wavelet-based method of processing data acquired with a low-cost UAV camera. The proposed, original method involves the application of algorithms for coarse filtration and precise filtering. In addition, a new way of calculating the recommended flight height was proposed. At the end, the accuracy assessment of this two-stage filtration process was examined. For this, point quality indices were proposed. The experimental results show that the proposed algorithm improves the quality of low-cost point clouds. The proposed methods improve the accuracy of determining the parameters of the lines by more than twice. About 10% of noise is reduced by using the wavelet-based approach.

Toward energy saving and high efficiency through an optimized use of a PET coarse filter: The development of a new electrostatically assisted air filter

Efficient particle removal technology with minimal pressure drop is urgently needed for both air purification and energy conservation. Compact electrostatically assisted air (cEAA) coarse filters can significantly enhance the filtration efficiency of low-efficiency filters without increasing the pressure drop, thus greatly reducing the energy consumption of ventilation fans. In this study, we developed a new structure for an electrostatically assisted air (EAA) filter, in which the corona charging and polarizing fields were separated and independently controlled. We experimentally evaluated the influencing factors on both single pass filtration efficiency and energy consumption of 6 EAA PET coarse fibrous filters: charging field intensity (Ec), polarizing field intensity (Ep), and PET filters’ characteristics. The EAA filter device increased the single pass filtration efficiency for 0.3–0.5 µm particles of a PET coarse filter from 0.4% (Ec = Ep = 0) to 57.0% (Ec = 5.9 kV/cm, Ep = 0) by particle charging, and then up to 99.0% (Ec = 5.9 kV/cm, Ep = 12.5 kV/cm) by filter polarizing. Increasing Ep enhanced filtration efficiency and reduced power dissipation of EAA filters at the same time. Although all filters are made of PET, several filter characteristics – including thickness, filling power, electrostatic half period, morphology and fiber diameter – strongly influence filtration efficiency. We compared the six EAA PET filters to traditional filters reported in the literature, and found that to have a more than 90% filtration efficiency for PM0.3–0.5, commercial filters (91.0%) need total power use per unit area (Pt) of at least 327 W/m2, while filters described in the literature (94.1%) need at least Pt = 76 W/m2, and EAA PET coarse filters (93.2%) need at least Pt = 39 W/m2. This study gives an understanding of the importance of media optimizing for EAA coarse filtration to achieve energy saving and high efficiency.

Fabrication of poly(ethylene glycol) particles with a micro-spherical morphology on polymeric fibers and its application in high flux water filtration

Abstract Polymeric coatings with micro-spherical morphology have a high surface area, which is advantageous for resins for heterogeneous chemical catalysis, for adsorption processes, nano-reactors, and anti-fouling coatings for water treatment membranes. The fabrication of stable, non-leachable micro-spherical polymers on solid surfaces is challenging. Here we introduce a straightforward method for fabricating polymeric particles with micro-spherical morphology on poly(ethylene terephthalate) fibers used as media for water filtration in microfiber technology. UV-initiated grafting with poly(ethylene glycol) methacrylate (PEGMA) monomers using benzophenone in aqueous solutions resulted in stable spherical particles coated on poly(ethylene terephthalate) threads, as revealed by FTIR, gravimetric degree of grafting, and SEM analyses. The micro-spherical morphology was unique to grafting with PEGMA monomers, whereas other types of methacrylate monomers resulted in smooth coatings. Grafting with PEGMA on high-flux water filtration cassette made of poly(ethylene terephthalate) fibers lead to enhanced performance and better dust removal capacity of the filter. The improved performance in coarse filtration is beneficial for treatment of water for agriculture, pretreatment facilities for freshwater supply, cooling water systems, and wastewater treatment. The protocol developed in this study is highly promising for both industrial and medical applications.

Evaluation of a portable in-house greywater treatment system for potential water-reuse in urban areas

ABSTRACTThis study aims at improving greywater reuse potential. An advanced physical filtration system named as GAC-MI-ME was developed to attain multi-grade effluents for versatile reuse of greywater. It consists of a matrix of treatment trains including coarse filtration, microfiltration, activated carbon, ultrafiltration, ultraviolet, and reverse osmosis. A preliminary set of experiments were conducted to characterize the greywater originating from shower, washbasin, and laundry. The samples were subsequently treated through GAC-MI-ME system. It was observed that the activated carbon along with microfiltration and coarse filtration played vital roles as pre-filtration for ultrafiltration and reverse osmosis. The contaminant load distributions of GAC-MI-ME system were observed with an average of 90.4% turbidity and 53.2% of biochemical oxidation demand (BOD5) as the pre-filtration, whereas the effluents at ultrafiltration and reverse osmosis showed unrestricted water reuse possibilities. The GAC-MI-ME system can be envisioned as advancement to the conventionally applied greywater treatments.

CT-texture analysis of subsolid nodules for differentiating invasive from in-situ and minimally invasive lung adenocarcinoma subtypes.

The purpose of this study was to evaluate the usefulness of computed tomography-texture analysis (CTTA) in differentiating between in-situ and minimally-invasive from invasive adenocarcinomas in subsolid lung nodules (SSLNs). Two radiologists retrospectively reviewed 49 SSLNs in 44 patients. There were 27 men and 17 women with a mean age of 63±7 (SD) years (range: 47-78years). For each SSLN, type (pure ground-glass or part-solid) was assessed by consensus and CTTA was conducted independently by each observer using a filtration-histogram technique. Different filters were used before histogram quantification: no filtration, fine, medium and coarse, followed by histogram quantification using mean intensity, standard deviation (SD), entropy, mean positive pixels (MPP), skewness and kurtosis. We analyzed 13 pure ground-glass and 36 part-solid nodules corresponding to 16 adenocarcinomas in-situ (AIS), 5 minimally invasive adenocarcinomas (MIA) and 28 invasive adenocarcinomas (IVA). At uni- and multivariate analysis CTTA allowed discriminating between IVAs and AIS/MIA (P<0.05 and P=0.025, respectively) with the following histogram parameters: skewness using fine textures and kurtosis using coarse filtration for pure ground-glass nodules, and SD without filtration for part-solid nodules. CTTA has the potential to differentiate AIS and MIA from IVA among SSLNs. However, our results require further validation on a larger cohort.

Combined use of an electrostatic precipitator and a high-efficiency particulate air filter in building ventilation systems: Effects on cardiorespiratory health indicators in healthy adults.

High-efficiency particulate air (HEPA) filtration in combination with an electrostatic precipitator (ESP) can be a cost-effective approach to reducing indoor particulate exposure, but ESPs produce ozone. The health effect of combined ESP-HEPA filtration has not been examined. We conducted an intervention study in 89 volunteers. At baseline, the air-handling units of offices and residences for all subjects were comprised of coarse, ESP, and HEPA filtration. During the 5-week long intervention, the subjects were split into 2 groups, 1 with just the ESP removed and the other with both the ESP and HEPA removed. Each subject was measured for cardiopulmonary risk indicators once at baseline, twice during the intervention, and once 2weeks after baseline conditions were restored. Measured indoor and outdoor PM2.5 and ozone concentrations, coupled with time-activity data, were used to calculate exposures. Removal of HEPA filters increased 24-hour mean PM2.5 exposure by 38 (95% CI: 31, 45) μg/m3 . Removal of ESPs decreased 24-hour mean ozone exposure by 2.2 (2.0, 2.5) ppb. No biomarkers were significantly associated with HEPA filter removal. In contrast, ESP removal was associated with a -16.1% (-21.5%, -10.4%) change in plasma-soluble P-selectin and a -3.0% (-5.1%, -0.8%) change in systolic blood pressure, suggesting reduced cardiovascular risks.

Radiocarbon Dating of Bones at the LARA Laboratory in Bern, Switzerland

AbstractThe Laboratory for the Analysis of Radiocarbon with AMS (LARA) was established at the University of Bern in 2013. Since then, the quality of sample preparation and radiocarbon measurement procedures have been validated for different materials such as plant remains, macrofossils, bulk sediment, charcoals, and wood. This article presents the optimization of sample pretreatment of bones based on protocols described in the literature. The extraction of collagen was performed with an acid-base-acid treatment, gelatinization, coarse filtration, lyophilization, and graphitization. Dating results were validated as satisfactory for the Holocene by investigation of 36 individual samples previously dated by other 14C laboratories including VIRI/SIRI materials and from well-known archaeological contexts. An additional blank contribution for bone treatment was determined by comparison with the preparation of other sample materials. The cases of two outliers from the Holocene were studied in detail.

Removal of metallic anions from dilute aqueous solutions by polymer–surfactant aggregates

A new application of polymer–surfactant aggregates has been developed to remove dilute metallic anions, such as CrO42− and Fe(CN)63−, from aqueous solutions. This process uses anionic polymers, such as poly(sodium 4-styrenesulfonate) (PSS) or poly(acrylic acid) (PAA), as a back-bone structure onto which cationic surfactants, such as myristyl trimethyl ammonium bromide (MTAB), form micelle-like aggregates. The resulting structures, called polymer–surfactant aggregates (PSAs), have the ability to remove anions from solutions, and to form larger flocculated aggregates through a process of intermolecular association. The flocculated aggregates can then be separated out from the solution through a settling or coarse filtration step. In the work presented here, the results show that 99% of 0.1mM Fe(CN)63− and 80% of 0.2mM CrO42− can be removed at optimum dosages. The change in conductivity with the change in surfactant concentration is plotted to reveal changes in the state of the system, and to detect the point of formation of the PSAs. The results indicate that the PSAs, which form at surfactant concentrations well below the critical micellar concentration, are responsible for removing the metallic anions. This process is effective for metallic anion removal over a pH range from 4.5 to 6 and a temperature range from 5 to 50°C. Furthermore, both salt and organic contaminants do not significantly interfere with the anion removal efficiency. Such a PSA process thus has potential applications for the efficient removal of dilute anions, and metallic anions in particular, during process effluent water treatment.