Filter Compartment Research Articles

АНАЛИЗ ПРОБЛЕМ, ВОЗНИКАЮЩИЕ ПРИ ЭКСПЛУАТАЦИИ ПЕСЧАНЫХ СКВАЖИН

The article considers the causes of the formation of mechanical impurities in deep pump wells and the consequences that it entails for the listed reasons. The impact of solid floating particles in the liquid on the well equipment and the importance of improving the filtration technology of sand- containing liquid to prevent it has been noted. As a method used in the fight against mechanical impurities, the advantages and disadvantages of the filter design, which washes the filter element without lifting the pumping equipment, and the V-shaped wire slotted grilles made of durable stainless steel located in the filter compartment are considered. In practical methods of combating mechanical impurities, the main directions of technology for equipping the bottom areas of wells with filters and the main criteria for combating the negative effects of mechanical impurities are indicated. Based on the special importance of the problem of reducing solid floating particles in the production of a gas-liquid mixture, several methods of insulating sand from impurities used in oil production are considered to protect deep pumping equipment. It is established that solving the problem of increasing the reliability of pumping equipment in the presence of solid float particles in the reservoir fluid requires an integrated approach to the selection of technical means. Analysis of the operability of existing filters in the intake of deep pumps showed that they have low efficiency in the fight against solid floating particles, including the need to periodically raise the pumping equipment for cleaning due to the adhesion of solid floating particles to the surface

Evaluation of an aerobic granular sludge reactor with biological filtration (AGS-BF reactor) in municipal wastewater treatment: A new configuration

Aerobic Granular Sludge (AGS) technology is considered promising, but many aspects are being studied and developed to increase system reliability. In this regard, the research assessed the performance of a conventional AGS (R1) sequencing batch reactor (SBR) system compared to a new AGS design through the inclusion of a biological filter (BF) compartment in the upper zone (R2), treating municipal wastewater. BF insertion in R2 improved total nitrogen removal (> 85 %) and effluent clarification. Effluent total suspended solids (TSS) average values of 44.1 and 17.1 mg/L were found for R1 and R2, respectively. Sludge production was evaluated, and the yield coefficient (Y) and sludge concentration were different in the two reactors. The new system (R2) can be an interesting alternative to improve some aspects of conventional AGS reactors, such as denitrification and nitrite accumulation, effluent TSS concentration, and system reliability increase during periods of instability and granules breakage.

Coronavirus disease 2019 (COVID-19): challenges and management of aerosol-generating procedures in dentistry.

Data sources Experimental investigation.Study design A retrospective review to evaluate the use of a negative-pressure otolaryngology viral isolation drape (NOVID) system to reduce cross-infection through aerosol. The apparatus consists of a plastic drape suspended over the surgical field in the head and neck region with a smoke evacuator suction placed inside the chamber with an ultra-low penetrating air (ULPA) efficiency rating and a fluid suction high-efficiency particulate air (HEPA) filter compartment. Spread of patient secretions and droplet formation was evaluated using 1% fluorescein dye in 10 ml of normal saline and ultraviolet light. The dye was applied topically in the nasal cavity and nasopharynx preoperatively and intraoperatively prior to the use of instruments such as micro-debrider, electrocautery and high-speed drilling. Following completion of the surgical procedure, an ultraviolet Wood's lamp was used to evaluate the presence of droplets on the surgical drapes and surgical gowns of the operating team.Results The study sample consisted of four patients who underwent endonasal endoscopic surgical procedures; two of these patients required concurrent endoscopic sinus surgery. A micro-debrider was used in three cases; electrocautery in three cases, while a high-speed drilling was employed in two cases. Presence of fluorescein was identified around the patients' nares; on the chest wipe and instrument tray in all four patients. Dye contamination was noted on the gauze placed over the smoke evacuator (two cases of skull base surgery); no fluid droplets were identified beyond the nares or the smoke evacuator (two cases of sinus surgery). However, fluid contamination was identified underneath barrier several centimetres away from the nares (one case of trans-sphenoidal surgery). Droplets were also identified on the surgeon's gown in the abdominal region in all cases and on the arm region in one case. In one case, droplets were also identified on the abdominal region of the nurse, but this was attributed to cross contamination from surgical gauze and instruments. Conclusions This retrospective study provides preliminary data on aerosol and droplet contamination during endonasal and transoral surgery performed under a negative pressure isolation drape system. Although the authors did not screen patients for SARS-CoV-2, they propose smoke evacuator ULPA filter attachment is appropriate to capture particles down to 0.1 microns including SARS-CoV-2 which is 0.125 microns. It would be helpful to see direct evidence to support this claim in future studies. The authors have not provided details regarding set-up time and training requirements for effective application of the isolation drape apparatus or the associated costs etc. It would have also been helpful if the authors could comment on any potential difficulties in undertaking the surgical procedure with the isolation system in place. The sample size is limited to four patients and variations in the magnitude and extent of aerosol contamination needs to be investigated further before drawing any conclusions. Although unlikely, this study design did not capture the presence of aerosol/droplets in the air within the operating room which may follow removal of the isolation drape system or from exposed surgical instruments. Notwithstanding the limitations of the design, negative-pressure aspiration of air under a chamber barrier is likely to minimise the contamination from aerosol and droplet during endonasal and transoral surgery.

Design of Small Lawn Garbage Sweeper

In view of the fact that the leaves and white garbage in the lawns are difficult to clean, this paper designed a small lawn garbage sweeper. The motor drives the cleaning roller and the traveling mechanism to realize the automatic cleaning and recycling of garbage. The author designed a filter compartment and a compacting mechanism in the recycling bin to complete the preliminary screening of the garbage. Finally, the static analysis of the rear axle was carried out by ANSYS software, showing that the axle can meet its stiffness requirements.

The Enhancement of Pre-Storage Filtration Efficiency for the Rainwater Harvesting System in Malaysia

A conventional design of rainwater harvesting system collects and directs the rainwater through water piping from roof of building to the water storage. The filtration system which locates before the water tank storage and first flush bypass system is the main focus of the research. A filtration system consists of a control volume of filter compartment, filter screen (stainless steel mesh) and water piping that direct the water flow. The filtration efficiency of an existing filter “3P Volume Filter VF1” by industrial company is enhanced. A full scale filter design prototype with filter screen of 1000 μm stainless steel metal mesh is tested to compare with the original filter system design. Three types of water inlet setups are tested. Among the proposed water inlet setups, the 90° inlet setup with extension provides the best filtration rate per unit time, following by the 45° inlet setup. The 45° and 90° inlet setup has similar filtration efficiency at low to medium flow rate while 45° inlet setup has better efficiency at high flow rate. The filtration efficiency with the 90° inlet setup with extension is observed to maintain at highest value at medium to high flow rate. The overall filtration performance achieved by the 90° inlet setup with extension at low to high flow rate is between 34.1 to 35.7%.

An integrated ecosystem incorporating renewable energy leading to pollution reduction for sustainable development of craft villages in rural area: a case study at sedge mats village in Mekong Delta, Vietnam

The sedge mats (dyeing, weaving processes, and small-scale livestock farm at the same place) craft villages in the Mekong Delta (Vietnam) are the most popular craft villages in Vietnam, especially in the Mekong Delta area. These craft villages generate typical emissions such as exhaust gas from burning fuel, wastewater from the sedge mats dyeing and weaving process, wastewater from livestock farm, and solid waste. In this study, an ecological system, so-called VICRAIZES (Vietnam Craft villages Agro-based Industrial Zero Emission System), has been developed with the purpose to decrease pollution and enhance resource efficiency at those craft villages. The proposed ecosystem focused on measures such as (1) biogas tank (using residue pieces of solid sedge mats from weaving processing) supplied gas for burning the dyeing tank, (2) wastewater treatment system combining three components: innovative septic tank having upward flow thin baffles, anaerobic filter compartment, and bio-pond, and (3) composting area. The system was applied for a number of household craft villages in Dong Thap Province, Vietnam. The results of system demonstration show significant emission decreases: 93 % greenhouse gas (CO2 and CH4), 97 % BOD5 in wastewater, around 30 kg/day biodegradable garbage are composted and used as organic fertilizers at the household needs (which increase family income of around 115 million VND/year), low initial investment and operating cost, simple operating procedure, etc., which are favorable and applicable at the low income sedge mats dyeing and weaving craft villages in the Mekong Delta area, Vietnam, and probably at other developing countries. The VICRAIZES system implementation shows remarkable benefits/advantages on environmental, economic, and technical aspects giving real chances for more comprehensive application at similar craft villages in Vietnam and possibly in other developing countries.

Suspension trapping (STrap) sample preparation method for bottom‐up proteomics analysis

Despite recent developments in bottom-up proteomics, the need still exists in a fast, uncomplicated, and robust method for comprehensive sample processing especially when applied to low protein amounts. The suspension trapping method combines the advantage of efficient SDS-based protein extraction with rapid detergent removal, reactor-type protein digestion, and peptide cleanup. Proteins are solubilized in SDS. The sample is acidified and introduced into the suspension trapping tip incorporating the depth filter and hydrophobic compartments, filled with the neutral pH methanolic solution. The instantly formed fine protein suspension is trapped in the depth filter stack-this crucial step is aimed at separating the particulate matter in space. SDS and other contaminants are removed in the flow-through, and a protease is introduced. Following the digestion, the peptides are cleaned up using the tip's hydrophobic part. The methodology allows processing of protein loads down to the low microgram/submicrogram levels. The detergent removal takes about 5 min, whereas the tryptic proteolysis of a cellular lysate is complete in as little as 30 min. We have successfully utilized the method for analysis of cellular lysates, enriched membrane preparations, and immunoprecipitates. We expect that due to its robustness and simplicity, the method will become an essential proteomics tool.

Bacterial community structure of a full-scale biofilter treating pig house exhaust air

Biological air filters represent a promising tool for treating emissions of ammonia and odor from pig facilities. Quantitative fluorescence in situ hybridization (FISH) and 16S rRNA gene sequencing were used to investigate the bacterial community structure and diversity in a full-scale biofilter consisting of two consecutive compartments (front and back filter). The analysis revealed a highly specialized bacterial community of limited diversity, dominated by a few groups of Betaproteobacteria (especially Comamonas) and diverse Bacteroidetes. Actinobacteria, Gammaproteobacteria, and betaproteobacterial ammonia oxidizers ( Nitrosomonas eutropha/ Nitrosococcus mobilis-lineage) were also quantitatively important. Only a few quantitative differences existed between the two filter compartments at the group level, with a lower relative abundance of Actinobacteria and a higher relative abundance of the Cytophaga– Flavobacteria group in the back filter compared to the front filter. These results confirmed the N. eutropha/ Nc. mobilis-lineage as the main ammonia oxidizers in pig house air filters and allowed first hypotheses for the key organisms involved in odor removal.

Rearing of Procypris rabaudi during early life-history stages

The early life-history of Chinese rock carp Procypris rabaudi was investigated during a 56-day rearing period: 318 artificially propagated P. rabaudi larvae were reared throughout metamorphosis in a small-scale recirculation system (345 L water volume, 10 x 18 L rearing tanks, 150 L storage and filter compartment with bioballs, 20-30 larvae L-1) at the Institute of Hydrobiology, Wuhan, Hubei Province, China. The newly hatched larvae had an initial total length of 8.93 +/- 0.35 mm SD (n = 10) at 3 days post-hatch and reached an average total length of 33.29 mm (+/- 1.88 mm SD, n = 10) 56 days after hatching. Length increment averaged 0.45 mm day(-1), resulting in a mean growth of 24.4 mm within the 56-day period. High mortality rates of up to 92% derived from an introduced fungus infection and subsequent treatment stress with malachite green. Our results indicate that Chinese rock carp can be raised successfully from artificially fertilized eggs. We therefore assume this species to be a candidate for commercial aquaculture.

Anion Channels, Including ClC-3, Are Required for Normal Neutrophil Oxidative Function, Phagocytosis, and Transendothelial Migration

NADPH oxidase activity, phagocytosis, and cell migration are essential functions of polymorphonuclear leukocytes (PMNs) in host defense. The cytoskeletal reorganization necessary to perform these functions has been extensively studied, but the role of cell volume regulation, which is likely dependent upon anion channels, has not been defined. Mice lacking the anion channel ClC-3 (Clcn3(-/-)) died from presumed sepsis following intravascular catheter placement, whereas Clcn3(+/+) littermates survived. We hypothesized that ClC-3 has a critical role in host defense and reasoned that PMN function would be compromised in these mice. Clcn3(-/-) PMNs displayed markedly reduced NADPH oxidase activity in response to opsonized zymosan and modestly reduced activity after phorbol 12-myristate 13-acetate. Human PMNs treated with the anion channel inhibitors niflumic acid or 5-nitro-2-(3-phenylpropylamino)benzoic acid had a very similar defect. ClC-3 protein was detected in the secretory vesicles and secondary granules of resting PMNs and was up-regulated to the phagosomal membrane. Clcn3(-/-) PMNs and human PMNs lacking normal anion channel function both exhibited reduced uptake of opsonized zymosan at 1, 5, and 10 min in a synchronized phagocytosis assay. Niflumic acid-treated PMNs also had impaired transendothelial migration in vitro, whereas migration in vivo was not altered in Clcn3(-/-) PMNs. Selective inhibition of the swelling-activated chloride channel with tamoxifen profoundly reduced PMN migration but had no effect on NADPH oxidase activity. In summary, PMNs lacking normal anion channel function exhibited reduced NADPH oxidase activity, diminished phagocytosis, and impaired migration. ClC-3 was specifically involved in the respiratory burst and phagocytosis.

Anaerobic ammonium-oxidizing (anammox) bacteria and associated activity in fixed-film biofilters of a marine recirculating aquaculture system.

Microbial communities in the biological filter and waste sludge compartments of a marine recirculating aquaculture system were examined to determine the presence and activity of anaerobic ammonium-oxidizing (anammox) bacteria. Community DNA was extracted from aerobic and anaerobic fixed-film biofilters and the anaerobic sludge waste collection tank and was analyzed by amplifying 16S rRNA genes by PCR using anammox-selective and universal GC-clamped primers. Separation of amplified PCR products by denaturing gradient gel electrophoresis and sequencing of the different phylotypes revealed a diverse biofilter microbial community. While Planctomycetales were found in all three communities, the anaerobic denitrifying biofilters contained one clone that exhibited high levels of sequence similarity to known anammox bacteria. Fluorescence in situ hybridization studies using an anammox-specific probe confirmed the presence of anammox Planctomycetales in the microbial biofilm from the denitrifying biofilters, and anammox activity was observed in these biofilters, as detected by the ability to simultaneously consume ammonia and nitrite. To our knowledge, this is the first identification of anammox-related sequences in a marine recirculating aquaculture filtration system, and our findings provide a foundation for incorporating this important pathway for complete nitrogen removal in such systems.

DO INDUCED SECONDARY FLOWS AUGMENT THE CLEARANCE OF PROTEIN-BOUND SUBSTANCES DURING ALBUMIN HEMODIAFIL-TRATION?

Objective: Removal of protein-bound toxins such as bilirubin by albumin hemodiafiltration (HDF) has been applied in patients with hepatic failure. As toxins must he transferred from perfusate to dialysate albumin binding sites, the efficiency of HDF may be limited by the laminar flow in the filter compartments where only a thin layer of fluid contacts the fiber surface. We hypothesized that disruption of laminar flow through filter agitation would enhance bilirubin transfer during HDF. Methods: An in vitro continuous HDF circuit was used with fixed volume perfusate and dialysate compartments. Unconjugated bilirubin was added to sheep plasma (10 mg/dl) and perfused through an albumin-impregnated polyalkyl sulfone hemofilter against a recirculating albumin-rich dialysate (10 g/dl) with matched flow rates. One group of filters (n = 3) was vigorously agitated during HDF along its long axis at approximately 8 Hz. A second group (n = 3) remained stationary. Plasma bilirubin levels were maintained between 8 and 12 mg/dl by continuous infusion of bilirubin. Dialysate bilirubin concentrations were measured over 3 hours. Bilirubin transfer rates were compared using repeated-measures ANOVA. Results: At 3 hours, 19% more bilirubin was transferred by the agitated filter than by the stationary filter (22.5±3.8 vs. 18.9±2.3 mg, p = NS). The transfer rate was highest for both groups in the first 30 minutes, but was 70% greater in the agitated filter (0.233±0.064 vs. 0.137±0.024 mg/min, p=0.068). However, this rate difference was not maintained beyond 90 minutes. Conclusions: Bilirubin transfer may be enhanced by the introduction of secondary flows, especially in the first 90 minutes of HDF. Mixing at the fluid-fiber interface may be an important determinant of hemofilter performance. Further studies to elucidate the factors responsible may influence future hemofilter design and ultimately the efficiency of extra-corporeal hepatic support.

The C.E.B.A.S.-Minimodule: behaviour of an artificial aquatic ecological system during spaceflight.

The C.E.B.A.S.-Minimodule, a closed aquatic ecosystem integrated into a middeck locker and consisting of a Zoological (animal tanks), a Botanical (plant bioreactor), a Microbial (bacteria filter) and an Electronic Component (data acquisition/control system) was flown on the STS-89 spaceshuttle mission in January 1998 for 9 days. Preflight the plant bioreactor was loaded with 53 g of Ceratophyllum demersum (coontail) and the animal tanks with 4 adult pregnant females of the fish, Xiphophorus helleri (sword-tails), 200 juveniles of the same species less than 1 week of age, 38 large and 30 juvenile Biomphalaria glabrata water snails. The filter compartment was filled with 200 g of lava grain inoculated with laboratory strains of ammonia-oxidizing bacteria. A ground reference was undertaken with the same biological setup with a delay of 4 d. After an adaptation period of 5 d the system was closed and integrated into the spaceshuttle one day before launch. Video recordings of the animals were automatically taken for 10 minutes in 2-hour periods; the tapes were changed daily by the astronauts. The chemical and physical data for the aquatic system were within the expected range and were closely comparable in comparison to the ground reference. After 9 d under space conditions, the plant biomass increased to 117 g. The plants were all found in very good condition. All 4 adult female fish were retrieved in a good physiological condition. The juvenile fishes had a survival rate of about 33%. Almost 97% of the snails had survived and produced more than 250 neonates and 40 spawning packs. All samples were distributed according to a defined schedule and satisfied all scientific needs of the involved 12 principal investigators. This was the first successful spaceflight of an artificial aquatic ecosystem containing vertebrates, invertebrates, higher plants and microorganisms self-sustained by its inhabitants only. C.E.B.A.S. in a modified form and biological setup is a promising candidate for the early space station utilization as a first midterm experiment.

Porcine Choroid plexus epithelial cells in culture: regulation of barrier properties and transport processes.

The epithelial cells of the choroid plexus are the structural basis of the blood-cerebrospinal fluid (CSF)-barrier. Here we summarise our recent efforts to culture those cells mainly on permeable supports in vitro. Isolated from porcine brains, we report a simple protocol for the primary culture using cytosine arabinoside as an additive that is cytotoxic for other cells except the plexus epithelial cells. Enhanced barrier properties are obtained by withdrawal of serum from the culture medium after confluency is reached. Cells improve their polarity, permeability for hydrophilic substrates is lowered, electrical resistance is increased tenfold, and a pH-gradient is built up across the cell monolayer. Polarised secretion of proteins and most importantly fluid secretion into the apical filter compartment was attained and proven to be dependent on the Na(+),K(+)-ATPase activity. Active transport processes (penicillin G, riboflavin, myo-inositol, ascorbic acid) were studied and clearly showed the involvement of the organic anion transporter. The permeability of the barrier was found to be regulated by cyclic adenosine monophosphate (cAMP). Moreover, we report that cell proliferation and differentiation is controlled by components of the extracellular matrix. The present culture model could now be used as an in vitro system to quantify drug transport across the blood-CSF-barrier.

Elimination of viruses, phages, bacteria and Cryptosporidium by a new generation Aquaguard point-of-use water treatment unit

The elimination of human viruses, phages, bacteria and Cryptosporidium oocysts by a new generation commercial Aquaguard purifier for the domestic treatment of drinking water, has been evaluated. The unit basically consists of a candle prefilter, activated carbon filter and ultraviolet irradiation compartment. Drinking water seeded with selected laboratory test strains of resistant micro-organisms was passed through the unit. Similar tests were carried out with sewage-contaminated river water and secondary treated waste water containing naturally occurring organisms. Test procedures were based on internationally accepted principles for the evaluation of point-of-use water treatment units, including a standard test protocol of the United States Environmental Protection Agency. Reduction in numbers of seeded test organisms at several log levels higher than those expected in water for which the unit is intended, was determined by the cultivation of viable organisms. In the case of seeded viruses and Cryptosporidium parvum oocysts the qualitative absence of nucleic acid was determined by the reverse transcriptase polymerase chain reaction (RT-PCR). At the design flow rate of one litre per minute, numbers of polio, hepatitis A, adeno types 2 and 41, rota SA11, human rota and astro viruses, as well as somatic and MS2 coliphages, and Escherichia coli. Streptococcus faecalis, Clostridium perfringens, total coliform bacteria, enterococci, heterotrophic bacteria and C. parvum oocysts, were reduced by more than 99.999 % in all waters tested. This efficiency conforms to specifications for such units. The quality of the treated water was well within microbiological limits of international specifications for drinking water.

The polarity of choroid plexus epithelial cells in vitro is improved in serum-free medium.

The influence of culture conditions on the development of normal characteristics of the choroid plexus epithelium has been investigated in vitro with respect to polarity, barrier properties, transport, and secretory activity. Withdrawal of serum supplement in the culture medium of cells grown on filters caused morphologically visible changes by an increased trimming of microvilli at the apical membrane side, which is accompanied by an increased expression of the Na+,K+-ATPase. Moreover cells under serum-free conditions exhibit structural changes in tight junctional zonula occludens protein-1 (ZO-1) organization, a reduced permeability, and a drastically increased electrical resistance from 150 ohms x cm2 in the presence of serum to 1,500 ohms x cm2 after serum withdrawal. Under these conditions, cell monolayers are able to build up a transcellular proton gradient and to secrete fluid into the upper (apical) filter compartment, which is accompanied by a polarized secretion of proteins like transthyretin. Active transport of the dyes fluorescein and phenol red by the organic anion transporter is found to be driven by the Na+,K+-ATPase. We come to the conclusion that removal of serum favors the differentiation process of the plexus epithelium in vitro, which brings the cell culture model closer to the physiological situation in vivo. We present preliminary evidence that epidermal growth factor may be one component in serum preventing the proper in vitro differentiation.

Growth and macronutrient removal of water hyacinth in a small secondary sewage treatment plant

Studies have been made of the growth characteristics of water hyacinth, Eichhornia crassipes (Mart.) Solms, and its ability to remove N, P and K, in a secondary settling pond of a small secondary sewage treatment plant serving both the academic and residential blocks of the Swire Marine Laboratory, University of Hong Kong. The treatment plant consists of, in series, a primary settling tank, a trickling filter compartment and a secondary settling pond from which part of the treated wastewater is recycled to the primary settling tank while the remaining effluent (1 to 2 m 3 daily) mixes with and hence is diluted by the outflowing seawater from the aquarium system of the Swire Marine Laboratory before discharge to the sea. Samples of wastewater have been taken regularly from the primary sedimentation pond, the outflow of the trickling filter, the secondary settling pond and the effluent of the treatment plant (before mixing with aquarium outflow) since January, 1992. Physical, chemical and biological characteristics of the samples have been determined and are typical of secondary effluents, with a mean pH of about 7.5, total solids 1200 mg L −1, suspended solids 45 mg L −1, conductivity 2000 μS cm −1, salinity 1 ppt, dissolved oxygen 2 mg L −1, BOD 5 45 mg L −1, Kjeldahl-N 30 mg L −1, NH 4,-N 25 mg L −1, NO 3-N 4 mg L −1, total P 10 mg L −1, K 35 mg L −1 and total coliforms of less than 10 5 colonies 100 ml −1. Water hyacinth plants have been stocked in the secondary settling pond as an integral part of the treatment plant so as to improve the quality of, as well as to retrieving and recycling nutrient elements from, the wastewater. The plants are periodically harvested to maintain an active growing crop. The growth rate, standing crop biomass, tissue nutrient composition, nutrient storage and accumulation rate of two growth cycles, one from February 25 to March 18 (mean temperature 17.6°C) and the other from 22 April to 12 May (24.8°C) are reported. The water hyacinth assumed a relatively high standing crop biomass of 10 kg m −2 (5 to 6 t DM ha −1), and growth rates of 48 and 225 g m −2 day −1, respectively, for the first and second growth period. Nutrient storage capacities were relatively high, at about 20, 7.5 and 16.5 g m −2 for N, P and K, respectively. The nutrient composition was very high, reaching 5.42% for N, 1.97 for P, and 4.57 for K. Both the stem and lamina accumulated high levels of N, while the petiole had the highest level of P and K. Apart from nutrient removal, the water hyacinth also helped to decrease the suspended solids, BOD 5 value and total coliforms of the wastewater. It is concluded that water hyacinth improves the quality of wastewater in such small-scale sewage treatment plants and it is recommended that frequent harvests of water hyacinth would increase the treatment efficiency, especially during the active growing season with high temperatures coupled with intense solar radiation.

Functional characteristics of pediatric veno-venous hemofiltration

To evaluate the functional characteristics of continuous veno-venous hemofiltration in a pediatric size animal model. Prospective trial. Animal laboratory at a large university-affiliated medical center. Four-week old lambs (weight 12.2 +/- 1.3 kg). Veno-venous hemofiltration was performed in anesthetized lambs (n = 5, 12.2 +/- 1.3 kg) using a standard pediatric hemofilter and pumped blood and ultrafiltrate. We compared postdilution, predilution, and hemofiltration with counterflow dialysis. At net ultrafiltrate flows of 200, 400, and 600 mL/hr, we measured system pressures and urea clearance. Stable blood flow could reproducibly be achieved up to 140 mL/min (10 mL/kg/min); at higher flow demand, tubing collapse occurred. At blood flow rates of 5 to 10 mL/kg/min, ultrafiltrate flow of 1 mL/kg/min would create negative filter compartment pressure but consistently less negative than -500 mm Hg. During postdilution, predilution, and counterflow dialysis, urea clearance was virtually equal to ultrafiltrate flow. There was no increase in urea clearance when adding predilution or dialysis to basic postdilution. Veno-venous hemofiltration, using small filters and circuits in a pediatric size animal, can achieve stable blood flow up to 10 mL/kg/min. At this flow, ultrafiltrate flow of 1 mL/kg/min can produce a urea clearance of 1 mL/kg/min while keeping filter compartment pressure above maximal recommended negative pressures. Addition of dialysis in this nonuremic model did not increase urea clearance.

Some measurements of dust charge in an electrostatically enhanced fabric filter

A study of precharger characteristics and the role of current as well as the charge-to-mass ratio imparted to dust carried by a gas stream through a negative corona discharge has been undertaken on the CSIRO pilot-scale precharger/fabric filter located at the Mount Isa Mine lead smelter in North West Queensland, Australia. During the course of the experiment, charge-to-mass ratios of up to 50 μC/g were recorded at the outlet of a flat plate, transverse discharge electrode precharger. These levels of dust charge are seen to be in basic agreement with a theoretical calculation for diffusion-charged submicron particles. This work has also shown that less than 25% of the current imparted to the dust stream is actually intercepted by the fabric filter. Moreover, a consideration of the loss of dust charge during transport has led to the conclusion that an electrostatically driven prefiltering mechanism operates in the hopper of the precharged filter compartment and is responsible for approximately one half of the observed level of volume flow rate enhancement. Finally, a 90% reduction in the exposed area of the collector electrode was found to have no influence on precharger performance.