Enhanced pre-coat engineering (EPCE) for micro- and ultrafiltration: the solution for fouling?

2001 ◽  
Vol 1 (5-6) ◽  
pp. 151-156
Author(s):  
G. Galjaard ◽  
J. van Paassen ◽  
P. Buijs ◽  
F. Schoonenberg
Keyword(s):  
Surface Water ◽  
Ferric Hydroxide ◽  
Feed Water ◽  
Exploratory Research ◽  
Direct Filtration ◽  
Filtration Cycle ◽  
Net Flux ◽  
Net Fluxes ◽  
Very High ◽  
Ultrafiltration Process

The feasibility of ultra- and microfiltration depends strongly on the achieved net flux. Direct treatment of surface water frequently results in low net fluxes and high cleaning frequencies. Experiments have been conducted at constant flux on surface water with an ultrafiltration pilot plant with direct filtration, in-line coagulation and pre-coating (EPCE) with ferric hydroxide flocs. The aim was to control and reduce the rate of fouling. With the use of a pre-coat at the beginning of the filtration cycle a stable ultrafiltration process was obtained. This is contrary to the use of in-line coagulation and direct filtration which resulted, due to a very high fouling potential of the feed water, in high fouling rates at low fluxes. The result of this exploratory research is an important step towards a higher feasibility of micro- and ultrafiltration.

Improving the performance of dead-end ultrafiltration systems: comparing air and water flushing

2001 ◽  
Vol 1 (5-6) ◽  
pp. 97-106
Author(s):  
M. Kennedy ◽  
S. Siriphannon ◽  
S. van Hoof ◽  
J. Schippers
Keyword(s):  
Hollow Fiber ◽  
Shear Force ◽  
Feed Water ◽  
Cake Filtration ◽  
Maximum Flux ◽  
Filtration Cycle ◽  
System A ◽  
Dead End ◽  
Cake Layer ◽  
Net Flux

A cleaning protocol that effectively removes fouling from hollow fiber UF systems without excessive use of chemicals, product water or (long) down time is needed. Cross flushing with UF feed water has been reported to increase the net flux of hollow fiber systems by reducing the frequency of backwashing, the consumption of permeate and the system down time. In this study, the flux restoration achieved in a vertical and horizontal UF system employing an intermittent water and water/air cross flush were compared. The flux restoration in the vertical UF system was not improved by the addition of air to the water flush and a maximum flux restoration of 82% was achieved, irrespective of the presence of air. Similarly, in a horizontal ultrafiltration system, a maximum flux restoration of 82% was also achieved with a water flush (v = 1.63 m/s). However, the addition of air to the water flush decreased the flux restoration to 40% at the highest water/air ratio (33% air). Low flux restoration in the horizontal system was attributed to residual air in the module after cross flushing. Flushing with water alone (v = 1.63 m/s) yielded a wall shear stress of 16 Pa compared with 130 Pa and 279 Pa in the liquid film surrounding the air slugs in the horizontal and vertical UF system, respectively, with a water/air ratio of 2:1. Despite the high shear force on the cake layer accumulated when air was added to the system, the maximum flux restoration was 82% both with and without air. This was attributed to the fact that it was the filtration mechanism and not the shear force on the cake layer that limited flux restoration during cross flushing. To improve the flux restoration that can be achieved by the cross flushing process, the filtration mechanism must be manipulated to minimize blocking filtration and induce cake filtration from the beginning of each filtration cycle.

scholarly journals Cation Regulation in the Smooth Muscle of Frog Stomach

1967 ◽  
Vol 50 (6) ◽  
pp. 1517-1546 ◽  
Author(s):  
Elizabeth W. Stephenson
Keyword(s):  
Smooth Muscle ◽  
High Rate ◽  
Stomach Muscle ◽  
Cation Composition ◽  
Wide Range ◽  
Frog Stomach ◽  
Net Flux ◽  
Net Fluxes ◽  
Very High

Cation composition of frog smooth muscle cells was investigated. Fresh stomach muscle rings resembled skeletal muscle, but marked Na gain and K loss followed immersion. Mean Na (49.8–79.7 mM/kg tissue) and K (61.8–80.1 mM/kg tissue) varied between batches, but were stable for long periods in vitro. Exchange of 6–30 mM Na/kg tissue with 22Na was extremely slow and distinct. Extracellular water was estimated from sucrose-14C uptake. Calculated exchangeable intracellular Na was 9 mM/kg cell water, and varied little. Thus steady-state transmembrane cation gradients appeared to be steep. K-free solution had only slight effects. Ouabain (10-4 M) caused marked Na gain and reciprocal K loss; at 30°C, Na and K varied linearly with time over a wide range of contents, indicating constant net fluxes. Net fluxes decreased with temperature decrease. 22Na exchange in ouabain-treated tissue at 20–30°C was rapid and difficult to analyze. The best minimum estimates of unidirectional Na fluxes at 30°C were 10–12 times the constant net flux; constant pump efflux may explain these findings. The rapidity of Na exchange may not reflect very high permeability, but it does require a high rate of transport work.

The habitable zone of Earth-mass planets around 47 UMa: results for land and water worlds

2003 ◽  
Vol 2 (1) ◽  
pp. 35-39 ◽  
Author(s):  
S. Franck ◽  
M. Cuntz ◽  
W. von Bloh ◽  
C. Bounama
Keyword(s):  
Surface Water ◽  
System Approach ◽  
Distinct Type ◽  
Integrated System ◽  
Habitable Zone ◽  
Stable Orbit ◽  
The Earth ◽  
Earth Like Planets ◽  
Very High

In a previous paper, we showed that Earth-type habitable planets around 47 UMa are in principle possible if a distinct set of conditions is warranted. These conditions include that the Earth-type planets have successfully formed and are orbitally stable and, in addition, that the 47 UMa star–planet system is relatively young ([lsim ]6 Gyr). We now extend this study by considering Earth-like planets with different land/ocean coverages. This study is again based on the so-called integrated system approach, which describes the photosynthetic biomass production taking into account a variety of climatological, biogeochemical and geodynamical processes. This approach implies a special characterization of the habitable zone defined for a distinct type of planet. We show that the likelihood of finding a habitable Earth-like planet on a stable orbit around 47 UMa critically depends on the percentage of the planetary land/ocean coverage. The likelihood is significantly increased for planets with a very high percentage of ocean surface (‘water worlds’).

Acid-Base and Ionic Exchanges at Gills and Kidney After Exhaustive Exercise in the Rainbow Trout

1988 ◽  
Vol 136 (1) ◽  
pp. 461-481 ◽  
Author(s):  
CHRIS M. WOOD
Keyword(s):  
Rainbow Trout ◽  
Exhaustive Exercise ◽  
Strong Ion Difference ◽  
Dynamic Modulation ◽  
Extracellular Acidosis ◽  
Titratable Acid ◽  
Na Efflux ◽  
Net Flux ◽  
Ionic Exchanges ◽  
Net Fluxes

Unidirectional Na+ and Cl− fluxes, net fluxes of Na+, Cl−, other ions, titratable acid (TA), ammonia and acidic equivalents (net H+) across the gills, together with the comparable renal fluxes, were monitored throughout a 24-h period after exhaustive exercise (simple chasing) in the rainbow trout. The gills were the major site of flux. The renal excretion of [TA-HCO3−], ammonia, lactate and most electrolytes increased after exercise, coincident with diuresis. Relative to the gills, the kidney accounted for only 8% of net H+ flux, 0–15% of net electrolyte losses and 50% of lactate loss, though the latter was negligibly small. Approximately 1000 μequiv kg−1 of net H+ were transported across the gills to the water during the first 4h, and then fully recovered over the subsequent 8h, coincident with periods of extracellular acidosis and alkalosis recorded in previous studies. Ammonia efflux increased during the first 4h; changes in titratable acid flux and extracellular PNHNH3 and NH4+ levels suggest that this elevation occurred partially as NH3 diffusion in the first hour, and thereafter mainly as NH4+ exchange. Small net Na+ losses (≊300 μequivkg−1), moderate net K+ losses (≊600 μequiv kg−1) and large net Cl− losses (≊1200 μequiv kg−1) correlated well with previously reported plasma changes; only the Na+ deficit was fully corrected by 24 h. Na+ influx was stimulated and Cl− influx inhibited during the 0–4 h period of net H+ excretion, whereas Na+ influx returned to control levels and Cl− influx increased during the 4–12 h period of net H+ uptake. These data indicate dynamic modulation of Na+/NH4+,H+ and C1−/HCO3−,OH− exchanges; however, an excess of Cl− over Na+ efflux also contributed to net H+ excretion. Acidic equivalent flux correlated well with [Na+-Cl−] net flux, in accord with strong ion difference theory.

Net Fluxes of Water in the Isolated Gills of Anguilla Dieffenbachii

1974 ◽  
Vol 60 (3) ◽  
pp. 769-781
Author(s):  
T. J. SHUTTLEWORTH ◽  
R. F. H. FREEMAN
Keyword(s):  
Sea Water ◽  
Water Flux ◽  
Freshwater Teleost ◽  
Osmotic Permeability ◽  
Direct Measurements ◽  
Net Flux ◽  
Anguilla Dieffenbachii ◽  
Net Fluxes ◽  
Freshwater Eels ◽  
Net Water Flux

1. Measurements of net flux of water have been made on isolated gills removed from freshwater-adapted and seawater-adapted eels and incubated in various media of differing osmotic pressure. 2. From these measurements it has been possible to determine the osmotic permeability coefficient of the gill directly from the net water flux. The values obtained (0.50±0.14x10-5 cm.sec-1 for freshwater eels and 0.43±0.07x10-5 cm.sec-1 for seawater-adapted eels) indicate that there was no significant change in this parameter on adaptation of the eels to sea water. 3. The direct measurements made of the net water flux across the isolated gills appear to be compatible with the osmoregulatory pattern of eels as deduced by other workers using different techniques. In particular they illustrate and further emphasize the significance of drinking in the freshwater fish. 4. Calculations indicate that, for a freshwater teleost, the osmotic and ionic problems caused by drinking in fresh water have an insignificant energetic effect and hence, energetically, it matters little to the fish whether it drinks or not.

Teenagers' Socio and Cultural Values

2015 ◽  
pp. 60-81
Author(s):  
Georg Dutschke ◽  
Julio Garcia del Junco ◽  
Francisco Espansandín-Bustelo ◽  
Mariana Dutschke ◽  
Beatriz Palacios Florencio
Keyword(s):  
Young Adults ◽  
Cultural Values ◽  
Youth Unemployment ◽  
Cultural Dimensions ◽  
Adolescents And Young Adults ◽  
Exploratory Research ◽  
Individual Level ◽  
The Poor ◽  
Poor Academic Performance ◽  
Very High

Investigations related to national culture and young are becoming more important (Brown et al., 2002; Larson, 2011). Gelhaar et al. (2007) state that “there is great concern about the poor academic performance and wiling to entrepreneurship of the adolescents and young adults in European countries, especially in the southern regions, where youth unemployment is very high”. For Iberia it's very important that adolescents and young adults have the want to become entrepreneurs, by developing new projects but, mainly, by having entrepreneurship as a purpose for their professional life. Entrepreneurship should be developed both at an individual level and within the organizations. It´s key to achive success, since originates innovation, both incremental and disruptive. This exploratory research aims to identify the relations between teenagers' socio and cultural values and their want to become entrepreneurs. In concrete, if socio and cultural dimensions identified by Hofstede and Minkov (2010) are related with the want to become entrepreneur.

Direct filtration with preozonation for small water treatment systems

2004 ◽  
Vol 48 (11-12) ◽  
pp. 473-479 ◽  
Author(s):  
E. Yüksel ◽  
Ö Akgiray ◽  
E. Soyer
Keyword(s):  
Treatment Method ◽  
Silica Sand ◽  
Particle Removal ◽  
Raw Water ◽  
Particle Count ◽  
Direct Filtration ◽  
Small Water ◽  
On Line ◽  
Very High ◽  
Different Water Sources

The possibility of applying preozonation followed by direct filtration without the use of a coagulant is investigated. Filtration experiments have been carried out using four different water sources within Istanbul. A 1 m deep bed of 0.8-1.2 mm silica sand was used as the filter medium. The filter was operated at a rate of 11.5 m/hr. Raw water turbidities ranged from 2.3 NTU to 10.0 NTU. Effluent turbidity and particle count values were monitored using an on-line turbidimeter and an on-line particle counter. With all the waters studied in this work, preozonation improved particle removal in direct filtration. With three of the mentioned waters, it was possible to achieve turbidity values below 1.0 NTU without a coagulant by applying ozone at a rate between 1.7-1.8 mg/L. It was not possible to reduce the turbidity of one of the waters to below 2.7 NTU even with very high ozone dosages. The need for pilot testing before deciding if this treatment method is applicable to a given water is underlined.

scholarly journals Elution Is a Critical Step for Recovering Human Adenovirus 40 from Tap Water and Surface Water by Cross-Flow Ultrafiltration

2016 ◽  
Vol 82 (16) ◽  
pp. 4982-4993 ◽  
Author(s):  
Hang Shi ◽  
Irene Xagoraraki ◽  
Kristin N. Parent ◽  
Merlin L. Bruening ◽  
Volodymyr V. Tarabara
Keyword(s):  
Surface Water ◽  
Hydrophobic Interactions ◽  
Tap Water ◽  
Calf Serum ◽  
Cross Flow ◽  
Human Adenovirus ◽  
Deionized Water ◽  
Feed Water ◽  
Eluent Composition ◽  
Cross Flow Filtration

ABSTRACTThis paper examines the recovery of the enteric adenovirus human adenovirus 40 (HAdV 40) by cross-flow ultrafiltration and interprets recovery values in terms of physicochemical interactions of virions during sample concentration. Prior to ultrafiltration, membranes were either blocked by exposure to calf serum (CS) or coated with a polyelectrolyte multilayer (PEM). HAdV 40 is a hydrophobic virus with a point of zero charge between pH 4.0 and pH 4.3. In accordance with predictions from the extended Derjaguin-Landau-Verwey-Overbeek theory, the preelution recovery of HAdV (rpre) from deionized water was higher with PEM-coated membranes (rprePEM= 74.8% ± 9.7%) than with CS-blocked membranes (rpreCS= 54.1% ± 6.2%). With either membrane type, the total virion recovery after elution (rpost) was high for both deionized water (rpostPEM= 99.5% ± 6.6% andrpostCS= 98.8% ± 7.7%) and tap water (rpostPEM= 89% ± 15% andrpostCS= 93.7% ± 6.9%). The nearly 100% recoveries suggest that the polyanion (sodium polyphosphate) and surfactant (Tween 80) in the eluent disrupt electrostatic and hydrophobic interactions between the virion and the membrane. Addition of EDTA to the eluent greatly improved the elution efficacy (rpostCS= 88.6% ± 4.3% andrpostPEM= 87.0% ± 6.9%) with surface water, even when the organic carbon concentration in the water was high (9.4 ± 0.1 mg/liter). EDTA likely disrupts cation bridging between virions and particles in the feed water matrix or the fouling layer on the membrane surface. For complex water matrices, the eluent composition is the most important factor for achieving high virion recovery.IMPORTANCEHerein we present the results of a comprehensive physicochemical characterization of HAdV 40, an important human pathogen. The data on HAdV 40 surface properties enabled rigorous modeling to gain an understanding of the energetics of virion-virion and virion-filter interactions. Cross-flow filtration for concentration and recovery of HAdV 40 was evaluated, with postelution recoveries from ultrapure water (99%), tap water (∼91%), and high-carbon-content surface water (∼84%) being demonstrated. These results are significant because of the very low adenovirus recoveries that have been reported, to date, for other methods. The recovery data were interpreted in terms of specific interactions, and the eluent composition was designed accordingly to maximize HAdV 40 recovery.

How to optimize lichen relative growth rates in growth cabinets

2016 ◽  
Vol 48 (4) ◽  
pp. 305-310 ◽  
Author(s):  
Yngvar GAUSLAA ◽  
Md Azharul ALAM ◽  
Knut Asbjørn SOLHAUG
Keyword(s):  
Surface Water ◽  
Growth Rates ◽  
Filter Paper ◽  
High Growth ◽  
Growth Chamber ◽  
Lobaria Pulmonaria ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Very High

AbstractIn order to improve growth chamber protocols for lichens, we tested the effect of 1) wet filter paper versus self-drained nets as a substratum for lichens, and 2) gradual versus abrupt transitions between dark and light periods. For Lobaria pulmonaria (L.) Hoffm. cultivated on nets, RGR increased by 60% compared to those on wet papers, whereas abrupt on/off transitions between day/night gave as high growth rates as gradual transitions mimicking sunrise/sunset. Because thalli on nets had less surface water than those on papers, the higher RGR on nets likely resulted from less suprasaturation depression of photosynthesis. By supporting very high growth and eliminating any visible damage, the revised growth chamber protocols facilitate new functional lichen studies.

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