Low energy/cost desalination: low dose and low mean ion resident time in concentrate stream of electro-dialysis reversal

2011 ◽  
Vol 63 (9) ◽  
pp. 1855-1863 ◽  
Author(s):  
M. T. Myint ◽  
A. Ghassem ◽  
N. Nirmalakhandan
Keyword(s):  
Low Dose ◽  
Saturation Index ◽  
Membrane Surface ◽  
Saturation Level ◽  
Water Recovery ◽  
Allowable Limit ◽  
Membrane Surface Area ◽  
Langelier Saturation Index ◽  
Resident Time ◽  
Polar Reversal

Species, dose, and mean ion resident time (MIRTc) in the concentrate of electro-dialysis reversal (EDR) desalination are analysed. In the classical EDR, dimensions, flow, and velocity of dilute and concentrate are equal; Langelier saturation index (LSI) and CaSO4 saturation are used to control the scaling and fouling processes in concentrate, as such LSI<+2.16 for preventing CaCO3 from fouling and CaSO4 saturation level<200 for averting CaSO4 from precipitation. If LSI is more than allowable limit, acid is added in concentrate to keep CaCO3 continuously dissolving; if CaSO4 saturation level in concentrate is more than the allowable limit, sodium hexametaphosphate (SHMP) is added in concentrate to maintain CaSO4 dissolving. EDR, however, was successfully modernised to operate with the higher water recovery rate (R) without any anti-scalant and without acid; this new EDR operated with LSI at 2.29 and CaSO4 saturation level 358.9% at lower dose and lower MIRTc. Dose and MIRTc are proposed to address the controlling process. Monographs for the acids and SHMP requirements, and for the desalting cost including desalting power, membrane surface area, and chemicals usage, are developed. By lowering R and polar reversal interval, EDR can be operated at MIRTc<130 min; at MIRTc<130 min, desalting cost/ energy can be minimised by eliminating chemicals requirement.

scholarly journals Long-Running Comparison of Feed-Water Scaling in Membrane Distillation

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 173
Author(s):  
Mohammad Rezaei ◽  
Albraa Alsaati ◽  
David M. Warsinger ◽  
Florian Hell ◽  
Wolfgang M. Samhaber
Keyword(s):  
Tap Water ◽  
Saturation Index ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Salt Crystallization ◽  
Feed Water ◽  
Water Recovery ◽  
Permeate Flux ◽  
Salt Scaling ◽  
Precipitous Decline

Membrane distillation (MD) has shown promise for concentrating a wide variety of brines, but the knowledge is limited on how different brines impact salt scaling, flux decline, and subsequent wetting. Furthermore, past studies have lacked critical details and analysis to enable a physical understanding, including the length of experiments, the inclusion of salt kinetics, impact of antiscalants, and variability between feed-water types. To address this gap, we examined the system performance, water recovery, scale formation, and saturation index of a lab-scale vacuum membrane distillation (VMD) in long-running test runs approaching 200 h. The tests provided a comparison of a variety of relevant feed solutions, including a synthetic seawater reverse osmosis brine with a salinity of 8.0 g/L, tap water, and NaCl, and included an antiscalant. Saturation modeling indicated that calcite and aragonite were the main foulants contributing to permeate flux reduction. The longer operation times than typical studies revealed several insights. First, scaling could reduce permeate flux dramatically, seen here as 49% for the synthetic brine, when reaching a high recovery ratio of 91%. Second, salt crystallization on the membrane surface could have a long-delayed but subsequently significant impact, as the permeate flux experienced a precipitous decline only after 72 h of continuous operation. Several scaling-resistant impacts were observed as well. Although use of an antiscalant did not reduce the decrease in flux, it extended membrane operational time before surface foulants caused membrane wetting. Additionally, numerous calcium, magnesium, and carbonate salts, as well as silica, reached very high saturation indices (>1). Despite this, scaling without wetting was often observed, and scaling was consistently reversible and easily washed. Under heavy scaling conditions, many areas lacked deposits, which enabled continued operation; existing MD performance models lack this effect by assuming uniform layers. This work implies that longer times are needed for MD fouling experiments, and provides further scaling-resistant evidence for MD.

The macrophage capacity for phagocytosis

1992 ◽  
Vol 101 (4) ◽  
pp. 907-913 ◽  
Author(s):  
G.J. Cannon ◽  
J.A. Swanson
Keyword(s):  
Surface Area ◽  
Membrane Surface ◽  
Fc Receptors ◽  
Phagocytic Capacity ◽  
Membrane Surface Area ◽  
Murine Bone Marrow ◽  
Latex Beads ◽  
Endocytic Compartments ◽  
Frustrated Phagocytosis

Murine bone marrow-derived macrophages, which measure 13.8 +/− 2.3 microns diameter in suspension, can ingest IgG-opsonized latex beads greater than 20 microns diameter. A precise assay has allowed the determination of the phagocytic capacity, and of physiological parameters that limit that capacity. Ingestion of beads larger than 15 microns diameter required IgG-opsonization, and took 30 minutes to reach completion. Despite the dependence on Fc-receptors for phagocytosis of larger beads, cells reached their limit before all cell surface Fc-receptors were occupied. The maximal membrane surface area after frustrated phagocytosis of opsonized coverslips was similar to the membrane surface area required to engulf particles at the limiting diameter, indicating that the capacity was independent of particle shape. Vacuolation of the lysosomal compartment with sucrose, which expanded endocytic compartments, lowered the phagocytic capacity. This decrease was reversed when sucrose vacuoles were collapsed by incubation of cells with invertase. These experiments indicate that the phagocytic capacity is limited by the amount of available membrane, rather than by the availability of Fc-receptors. The capacity was also reduced by depolymerization of cytoplasmic microtubules with nocodazole. Nocodazole did not affect the area of maximal cell spreading during frustrated phagocytosis, but did alter the shape of the spread cells. Thus, microtubules may coordinate cytoplasm for engulfment of the largest particles.

scholarly journals Brush border protocadherin CDHR2 promotes the elongation and maximized packing of microvilli in vivo

2019 ◽  
Vol 30 (1) ◽  
pp. 108-118 ◽  
Author(s):  
Julia A. Pinette ◽  
Suli Mao ◽  
Bryan A. Millis ◽  
Evan S. Krystofiak ◽  
James J. Faust ◽  
...  
Keyword(s):  
Functional Capacity ◽  
Brush Border ◽  
Intestinal Tract ◽  
Membrane Surface ◽  
Careful Examination ◽  
Tissue Cell ◽  
Apical Surface ◽  
Membrane Surface Area ◽  
Solute Uptake

Transporting epithelial cells optimize their morphology for solute uptake by building an apical specialization: a dense array of microvilli that serves to increase membrane surface area. In the intestinal tract, individual cells build thousands of microvilli, which pack tightly to form the brush border. Recent studies implicate adhesion molecule CDHR2 in the regulation of microvillar packing via the formation of adhesion complexes between the tips of adjacent protrusions. To gain insight on how CDHR2 contributes to brush border morphogenesis and enterocyte function under native in vivo conditions, we generated mice lacking CDHR2 expression in the intestinal tract. Although CDHR2 knockout (KO) mice are viable, body weight trends lower and careful examination of tissue, cell, and brush border morphology revealed several perturbations that likely contribute to reduced functional capacity of KO intestine. In the absence of CDHR2, microvilli are significantly shorter, and exhibit disordered packing and a 30% decrease in packing density. These structural perturbations are linked to decreased levels of key solute processing and transporting factors in the brush border. Thus, CDHR2 functions to elongate microvilli and maximize their numbers on the apical surface, which together serve to increase the functional capacity of enterocyte.

scholarly journals Effect Of Surface Area Of Dialyzer Membrane On The Adequacy Of Haemodialysis

2012 ◽  
Vol 7 (2) ◽  
pp. 9-11 ◽  
Author(s):  
NS Chowdhury ◽  
FMM Islam ◽  
F Zafreen ◽  
BA Begum ◽  
N Sultana ◽  
...  
Keyword(s):  
Renal Disease ◽  
Surface Area ◽  
End Stage Renal Disease ◽  
Membrane Surface ◽  
Reduction Ratio ◽  
Urea Clearance ◽  
Membrane Surface Area ◽  
Stage Renal Disease ◽  
End Stage ◽  
Urea Reduction Ratio

Introduction: Patients with end stage renal disease require 12 hours of haemodialysis per week in three equal sessions (4 hours/day for 3 days/week). But the duration and frequency of treatment can be reduced by increasing the surface area of the dialyzer membrane. Methods: In this prospective study 40 patients of end stage renal disease receiving haemodialysis for more than six months were included to observe the effects of increment in the surface area of the dialyzer membrane on the adequacy of haemodialysis. Result: It was observed that 20 patients receiving haemodialysis on a dialyzer with membrane surface area of 1.2 m² did not have satisfactory solute clearance index. Urea reduction ratio was 45.9 ± 3.03 and fractional urea clearance (Kt/V) was 0.76 ± 0.09. On the other hand patients (20 cases) receiving haemodialysis on a dialyzer with membrane surface area of 1.3 m² had a urea reduction ratio 50.76± 5.16 and fractional urea clearance (Kt/V) 0.91 ± 0.16. All the patients of both groups received dialysis for 8 hours/week in two equal sessions (4 hours/day for 2 days/week). Statistically the increment was significant (p<0.001). Conclusion: This study reveals, adequacy of dialysis can be increased by increasing the surface area of the dialyzer membrane. So, considering the poor socioeconomic condition of Bangladesh and patients' convenience, a short duration, low cost dialysis regime can be tried by increasing the surface area of dialyzer membrane. DOI: http://dx.doi.org/10.3329/jafmc.v7i2.10387 JAFMC 2011; 7(2): 9-11

The ultrastructure of the cardiac Purkinje strand in the dog: a morphometric analysis

1983 ◽  
Vol 217 (1207) ◽  
pp. 191-213 ◽  
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Connective Tissue ◽  
Surface Area ◽  
Series Resistance ◽  
Membrane Surface ◽  
Light And Electron Microscopy ◽  
Total Surface Area ◽  
Membrane Surface Area ◽  
Extracellular Ions

Purkinje strands from both ventricles of adult mongrel dogs were excised, and electrical properties were studied by the voltage-clamp technique. The strands were then examined with light and electron microscopy and structural properties were analysed by morphometric techniques. The canine Purkinje strand contains (by volume) about 28% myocyte and 55% dense outer connective tissue. The remainder of the volume is taken up by the inner shell of loosely packed connective tissue within 10 μm of a myocyte membrane. These volume fractions vary considerably from one strand to another. Clefts less than 10 μm wide occupy 18% of the myocyte volume and clefts less than 1 μm wide occupy 1%. The membrane surface area of the myocytes can be divided into three categories by reference to the size of the adjacent cleft. About 47.8% of the membrane surface area faces clefts wider than 1 μm, another 22.2% faces clefts between 0.1 and 1 μm wide, and the final 30% faces clefts less than 0.1 μm wide. The surface area facing the narrowest clefts (less than 0.1 μm wide) is divided between nexuses 3%, desmosomes 10%, and unspecialized membrane 17% (each figure is expressed as a percentage of the total surface area of myocyte membrane). The canine Purkinje strand has a more favourable anatomy than the sheep Purkinje strand for most physiological experiments. We expect that the complicating effects of series resistance and change in the concentration of extracellular ions will be much smaller than in sheep strands, but still not negligible.

The influence of aeration on the change in corrosiveness and aggressiveness of groundwater

2015 ◽  
Vol 16 (2) ◽  
pp. 445-452 ◽  
Author(s):  
Tadeusz Siwiec ◽  
Magdalena M. Michel ◽  
Lidia Reczek ◽  
Piotr Nowak
Keyword(s):  
Carbon Dioxide ◽  
Water Treatment ◽  
Saturation Index ◽  
Stability Index ◽  
Water Layer ◽  
Water Stability ◽  
Air Bubbles ◽  
High Concentration ◽  
Aeration Time ◽  
Langelier Saturation Index

A high concentration of aggressive carbon dioxide disturbs many technological processes in water treatment. It also causes the development of corrosion in steel and concrete. De-acidification of groundwater by means of air bubbles alters pH and the concentration of aggressive carbon dioxide. This was investigated for the variables of air flow (Q = 20–50 L h−1) and height of water layer (H = 25–75 cm) as well as aeration time (t = 0–20 min). The obtained three-parameter models showed good correlation with the experimental results, except in a few cases where r2 was bigger than 0.9. Furthermore, they allow for prediction of an increase of pH and a decrease in concentration of aggressive carbon dioxide in aerated water. The effectiveness of de-acidification of groundwater was evaluated using indices of water stability (Langelier Saturation Index, Precipitation Index, Ryznar Stability Index, Aggressiveness Index and Index of Aggressiveness). Although as a result of aeration an increase of pH over 7 was observed, the non-corrosive values of the indices were not reached. This was due to a very low alkalinity of water, which was 0.7 meq L−1.

Clinical oxygen transfer comparison of the Terumo Capiox SX18 and SX25 membrane oxygenators

Perfusion ◽  
1998 ◽  
Vol 13 (2) ◽  
pp. 119-127 ◽  
Author(s):  
David W Fried ◽  
Theodore L Zombolas ◽  
Joseph J Leo ◽  
Hasratt Mohamed ◽  
Gabriel J Mattioni
Keyword(s):  
Pressure Drop ◽  
Oxygen Transfer ◽  
Membrane Surface ◽  
Shunt Fraction ◽  
Flow Rates ◽  
Membrane Surface Area ◽  
Blood Flows ◽  
Side Pressure ◽  
Membrane Oxygenators ◽  
Better Than

The purpose of this current study was to compare the Terumo Capiox SX18 (1.8 m2) with the recently released Capiox SX25 (2.5 m2). Specifically, their oxygen transfer slopes, degree of blood shunting, extrapolated maximum oxygen transfer, blood side pressure drop and oxygen transfer consistency were compared. The lower intercept value (0.209 vs 0.236) coupled with the flatter slope (0.00171 vs 0.00225) of the oxygen transfer line for the SX25 is consistent with improved oxygen transfer performance. A lower FiO2 value would be predicted for the SX25, to achieve a specific PaO2 value, when the oxygen transfer requirement is equal for both devices. Extrapolated maximum oxygen transfer for the SX25 (462.6 ml O2/min) was 36.2% higher than that for the SX18 (339.6 ml O2/min). When indexed to membrane surface area, the SX18 (188.7 ml O2/m2/min performed 2.0% better than the SX25 (185.0 ml O2/m2/min). Both the slope (3.110 vs 3.744) and the intercept (4.595 vs 6.223) of the shunt fraction line were lower for the SX25, indicating that a lower shunt fraction would be predicted for all clinical blood flow rates. The slope (23.934 vs 22.443) and intercept values (-28.388 vs -22.650) of the pressure drop lines for the two devices indicate that the blood side pressure drop, over the range of clinical blood flows, were within 2% of each other. Oxygen transfer consistency, when expressed as the standard deviation of the oxygenator performance index and the percentage of predicted shunt, was not statistically different for the two devices.

Sign in / Sign up

Export Citation Format

Share Document