Virus removal by soil passage at field scale and ground-water protection of sandy aquifers

2002 ◽  
Vol 46 (3) ◽  
pp. 123-129 ◽  
Author(s):  
J.F. Schijven ◽  
S.M. Hassanizadeh
Keyword(s):  
Rate Coefficient ◽  
Removal Rate ◽  
Virus Concentration ◽  
Current Guideline ◽  
Rate Parameter ◽  
Worst Case ◽  
Virus Removal ◽  
Virus Contamination ◽  
Time Required ◽  
Sandy Aquifers

Virus removal from groundwater by soil passage often appears to be much higher during the first few metres due to the presence of more favorable sites for attachment than thereafter. A model is presented which interprets virus removal as a function of collision efficiencies αbeta; and αλl, inactivation rate coefficient μll and rate parameter γ. Initial high removal is determined by αβ, which decreases exponentially at a rate γ to a constant base removal rate that is determined by αλ and μl. A hypothetical worst case was simulated to calculate the travel distance and time required for 9 log10 protection against virus contamination of groundwater wells in anoxic sandy aquifers. Unfavorable conditions for attachment were assumed. Virus was constantly leaking from a sewage pipe lying at the groundwater table. Mixing reduced virus concentration by 3.1 to 4.0 log10. For an additional 5.0 to 5.9 log10 protection against virus contamination by attachment and inactivation, residence times of about three to seven times longer than the current guideline of 60 days are needed, depending on abstraction rates, aquifer thickness and grain size of the sand.

Mitochondrial Ca2+ uptake is important over low [Ca2+]i range in arterial smooth muscle

2002 ◽  
Vol 283 (6) ◽  
pp. H2431-H2439 ◽  
Author(s):  
Tomoko Kamishima ◽  
John M. Quayle
Keyword(s):  
Smooth Muscle ◽  
Decay Time ◽  
Removal Rate ◽  
Arterial Smooth Muscle ◽  
Carbonyl Cyanide ◽  
Before And After ◽  
Intracellular Ca ◽  
Arterial Smooth Muscle Cells ◽  
Time Required ◽  
Loaded Voltage

Mitochondrial Ca2+ uptake is usually thought to occur only when intracellular Ca2+concentration ([Ca2+]i) is high. We investigated whether mitochondrial Ca2+ removal participates in shaping [Ca2+]i signals in arterial smooth muscle over a low [Ca2+]irange. [Ca2+]i was measured using fura 2-loaded, voltage-clamped cells from rat femoral arteries. Both diazoxide and carbonyl cyanide m-chlorophenylhydrazone (CCCP) depolarized the mitochondria. Diazoxide application increased resting [Ca2+]i, suggesting that Ca2+ is sequestered in mitochondria. Over a low [Ca2+]i range, diazoxide and CCCP slowed Ca2+ removal rate, determined after a brief depolarization. When [Ca2+]i was measured during sustained depolarization to −30 mV, CCCP application increased [Ca2+]i. When Ca2+ transients were repeatedly evoked by caffeine applications, CCCP application elevated resting [Ca2+]i. Caffeine-induced Ca2+ transients were compared before and after CCCP application using the half decay time, or time required to reduce increase in [Ca2+]i by 50% ( t ½). CCCP treatment significantly increased t ½. These results suggest that Ca2+ removal to mitochondria in arterial smooth muscle cells may be important at a low [Ca2+]i.

Dynamic Collision Detection Using Space Partitioning

1990 ◽  
Author(s):  
M. A. Ganter ◽  
B. P. Isarankura
Keyword(s):  
Collision Detection ◽  
Computation Time ◽  
Local Region ◽  
Detection Time ◽  
Space Partitioning ◽  
Worst Case ◽  
Simulated Environment ◽  
Time Required ◽  
Six Degree Of Freedom ◽  
Partitioning Technique

Abstract A technique termed space partitioning is employed which dramatically reduces the computation time required to detect dynamic collision during computer simulation. The simulated environment is composed of two nonconvex polyhedra traversing two general six degree of freedom trajectories. This space partitioning technique reduces collision detection time by subdividing the space containing a given object into a set of linear partitions. Using these partitions, all testing can be confined to the local region of overlap between the two objects. Further, all entities contained in the partitions inside the region of overlap are ordered based on their respective minimums and maximums to further reduce testing. Experimental results indicate a worst-case collision detection time for two one thousand faced objects is approximately three seconds per trajectory step.

Effect of Operating Conditions on the Chemical Phosphate Removal Using during Ferrous Iron Oxidation

2013 ◽  
Vol 807-809 ◽  
pp. 478-485 ◽  
Author(s):  
Ting Li ◽  
Wen Yi Dong ◽  
Hong Jie Wang ◽  
Jin Nan Lin ◽  
Feng Ouyang ◽  
...  
Keyword(s):  
Ferrous Iron ◽  
Removal Rate ◽  
Iron Oxidation ◽  
Operating Conditions ◽  
Phosphate Removal ◽  
Order Kinetic ◽  
Ferrous Iron Oxidation ◽  
Order Kinetic Model ◽  
Time Required ◽  
Kinetics Of

In this study, the effect of operating parameters and the co-existing ions on the phosphate removal during the ferrous iron oxidation was investigated. Results showed that with the increase of DO and [Fe (II)]0, the final phosphate removal rate both increased. But with increasing of pH, the final phosphate removal rate firstly increased and then decreased when the pH was higher than 8.0. The co-existing ions affected the final removal rate significantly, and the kinetics of phosphate removal followed the pseudo-first-order kinetic model. The corresponding kobs trends for the cation followed the order of Cu2+>Mn2+>Zn2+>NH4+-N. The presence of Cu2+ promoted the phosphate removal significantly. Compared with the control, , the time required to achieve 40 % phosphate removal rate, at the condition of 0.5 mg/L Cu2+, reduced from 60 min to 10 s. However, the selective anions inhibited the phosphate removal, due to the formation of Fe-anions complexes. The effect of selective anions on the phosphate removal rate constant decreased in the order of SO42->Cl-> NO3-.

Issues of operational integrity in membrane drinking water plants

2003 ◽  
Vol 3 (5-6) ◽  
pp. 73-80 ◽  
Author(s):  
W. Johnson ◽  
T. MacCormick
Keyword(s):  
Drinking Water ◽  
Laboratory Data ◽  
Full Scale ◽  
Human Pathogens ◽  
Membrane Systems ◽  
Case Scenario ◽  
Fiber Failure ◽  
Worst Case ◽  
Virus Removal ◽  
Water Plants

In the last five years over 100 microfiltration (MF) and ultrafiltration (UF) drinking water plants have been installed in Europe with a combined output of some 1,500 ML/day. The impetus behind this growth is concern over drinking water quality, regulatory pressure, the rapidly declining costs of membrane systems, and consumer pressures for non-chemical treatment. Although the principal justification for membrane plants is their capacity to remove human pathogens more effectively than conventional treatment, the ability of large plants to retain an integral barrier is not well understood. Currently available technology can monitor a full-scale membrane plant for integrity against passage of bacteria and parasites but not viruses. In essence the plant operator has to rely on the membrane manufacturer – on an assumption that if the membrane is not compromised at a level of 1 to 2 μm (the current practical level of measurement) it is also not compromised for virus removal. This paper quantifies the loss of integrity that can occur from membrane fiber failure. It explains the mathematical models used to describe bypass flow through compromised fibers and correlates the results with laboratory tests. Both are compared with artificially compromised fibers in a large full-scale operating plant. Under the worst case scenario where a fiber breaks close to the pot (collection end of the filtration module or element) the relative loss of integrity between alternative process designs from a single broken fiber can differ by as much as 2 log reduction values. The analysis demonstrates the need for monitoring methodology that that can track incremental changes in integrity to allow scheduled rather than emergency maintenance. It highlights the need for regulatory authorities to approve membrane systems based on actual operating performance in preference to laboratory data.

Virus removal by the domestic wastewater treatment system named Johkasou

1997 ◽  
Vol 35 (11-12) ◽  
pp. 187-191 ◽  
Author(s):  
M. Kaneko
Keyword(s):  
Removal Rate ◽  
Treatment Plant ◽  
Order Reduction ◽  
Domestic Wastewater ◽  
Coxsackievirus B3 ◽  
Virus Removal ◽  
E Coli ◽  
Domestic Wastewater Treatment ◽  
Small Model ◽  
Reducing Activity

Virus removal by a treatment plant for domestic wastewater (Johkasou), was investigated using a small model of the plant. Under standard BOD loading of 0.076 BOD kg/m3/day, 97% of E. coli phage T2, 98% of poliovirus 1 and 93% of coxsackievirus B3 were removed from inlet wastewater by the system. About 80% of the viruses in the influent were removed in the first and second anaerobic zones under the standard conditions. When the loading was increased to double the standard loading (0.152 kg BOD/m3/day) the removal rate decreased to 64%. Poliovirus 1 and coxsackievirus B3 were removed more easily than T2 phage. Assuming the stream in each zone was completely mixed, the virus reducing activity of microorganisms was estimated by the rate constant of the first order reduction equation. It was found that the higher the BOD loading rates, the lower the values of the constant.

Effects of flow velocity and depth on the rates of reaeration and bod removal in a shallow open channel

1997 ◽  
Vol 35 (8) ◽  
pp. 57-67
Author(s):  
Horng-Guang Leu ◽  
C. F. Ouyang ◽  
Tze-Yi Pai
Keyword(s):  
Analytical Solution ◽  
Flow Velocity ◽  
Open Channel ◽  
Rate Coefficient ◽  
Removal Rate ◽  
Sedimentation Coefficient ◽  
Inverse Correlation ◽  
Flow Conditions ◽  
Batch Tests ◽  
Bod Removal

This study developed an analytical solution of reaeration rate coefficient (K2) and modified the equation of BOD removal in a shallow artificial open channel. A series of well-controlled batch tests were carried out to measure the K2 and BOD removal rate in the channel at different flow conditions. The results of these tests indicated that measured K2 within the developing zone of the laminar boundary layer is better described by the analytical solution of this study than by the five semi-empirical formulae mentioned in this paper. On the other hand, a resuspension-sedimentation coefficient, Rs, was added to the BOD removal equation to describe the variation in BOD due to varied flow conditions. Based on the results of the experimental data the following conclusions in the BOD removal process were reached. It was found that a direct correlation exists between the flow velocity to depth ratio (U/h) and the deoxygenation rate coefficient (K1), but there is an inverse correlation between U/h and Rs as well. This modified BOD removal equation can predict BOD removal rate at different travel times or known downstream distances in an open channel under varied flow conditions.

scholarly journals Politeness and Stable Infiniteness: Stronger Together

2021 ◽  
pp. 148-165
Author(s):  
Ying Sheng ◽  
Yoni Zohar ◽  
Christophe Ringeissen ◽  
Andrew Reynolds ◽  
Clark Barrett ◽  
...  
Keyword(s):  
Preliminary Evidence ◽  
Satisfiability Modulo Theories ◽  
The Other ◽  
Combination Method ◽  
Improve Performance ◽  
Worst Case ◽  
Smart Contract ◽  
Shared Variables ◽  
Speed Up ◽  
Time Required

AbstractWe make two contributions to the study of polite combination in satisfiability modulo theories. The first is a separation between politeness and strong politeness, by presenting a polite theory that is not strongly polite. This result shows that proving strong politeness (which is often harder than proving politeness) is sometimes needed in order to use polite combination. The second contribution is an optimization to the polite combination method, obtained by borrowing from the Nelson-Oppen method. The Nelson-Oppen method is based on guessing arrangements over shared variables. In contrast, polite combination requires an arrangement over all variables of the shared sorts. We show that when using polite combination, if the other theory is stably infinite with respect to a shared sort, only the shared variables of that sort need be considered in arrangements, as in the Nelson-Oppen method. The time required to reason about arrangements is exponential in the worst case, so reducing the number of variables considered has the potential to improve performance significantly. We show preliminary evidence for this by demonstrating a speed-up on a smart contract verification benchmark.

Development of Techniques for Evaluating the Virus Removal Rate using Adenovirus

2015 ◽  
Vol 29 (6) ◽  
pp. 633-641
Author(s):  
Yoonjung Cho ◽  
◽  
Jaewon Lim ◽  
Dawoon Baek ◽  
Sang-Hoon Lee ◽  
...  
Keyword(s):  
Removal Rate ◽  
Virus Removal

scholarly journals Sediments from Arctic Tide-Water Glaciers Remove Coastal Marine Viruses and Delay Host Infection

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 123 ◽  
Author(s):  
Douwe Maat ◽  
Maarten Prins ◽  
Corina Brussaard
Keyword(s):  
Removal Rate ◽  
Interaction Strength ◽  
Host Population ◽  
Microbial Interactions ◽  
The Arctic ◽  
Virus Removal ◽  
Algal Virus ◽  
Fine Sediments ◽  
Coastal Marine ◽  
Marine Viruses

Over the past few decades, the Arctic region has been strongly affected by global warming, leading to increased sea surface temperatures and melting of land and sea ice. Marine terminating (tide-water) glaciers are expected to show higher melting and calving rates, with an increase in the input of fine sediment particles in the coastal marine environment. We experimentally investigated whether marine viruses, which drive microbial interactions and biogeochemical cycling are removed from the water column through adsorption to glacier-delivered fine sediments. Ecologically relevant concentrations of 30, 100 and 200 mg·L−1 sediments were added to filtered lysates of 3 cultured algal viruses and to a natural marine bacterial virus community. Total virus removal increased with sediment concentration whereby the removal rate depended on the virus used (up to 88% for an Arctic algal virus), suggesting a different interaction strength with the sediment. Moreover, we observed that the adsorption of viruses to sediment is a reversible process, and that desorbed viruses are still able to infect their respective hosts. Nonetheless, the addition of sediment to infection experiments with the Arctic prasinovirus MpoV-45T substantially delayed host lysis and the production of progeny viruses. We demonstrate that glacier-derived fine sediments have the potency to alter virus availability and consequently, host population dynamics.

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