Measurement of adhesion strengths and energy between calcium carbonate cake and filter cloth

Various devices in liquid-solid separation require mechanical cake discharge using different technologies. An incomplete cake discharge causes yield losses, cycle time increase, irregular cake formation, high mechanical constraints which decrease medium life time, excess consumption of cleaning liquors…. Currently, cake discharge is only assessed qualitatively by observations of filter cloth after discharge or quantitatively by weighing recovered solids. A prototype has been developed to carry out reliable and repeatable measurements by removing filter cloth from filter cake by shearing. This study presents results of experiments performed with calcium carbonate (which forms sticky cakes) and discusses the conditions of cake formation and cake detachment from filter cloth. It highlights the role of two main parameters: filter cloth characteristics and pressure.

Download Full-text

Zeit und gutes Leben

Zeitschrift für philosophische Forschung ◽

10.3196/004433020830955996 ◽

2020 ◽

Vol 74 (4) ◽

pp. 493-513

Author(s):

Holmer Steinfath

Keyword(s):

Internal Structure ◽

Good Life ◽

External Factor ◽

Life Time ◽

The Good Life ◽

Adequate Understanding ◽

Gutes Leben

Time is a neglected subject in recent, especially analytically minded reflections on the good life. The article highlights the fundamental role of time and temporality for an adequate understanding of the good life. Time functions both as an external factor with which we have to reckon in our practical deliberations and as an internal structure of living our lives. It is argued that striving for a good life also means striving for being in harmony with the time of one's life. The exploration of this idea allows to link analytical with phenomenological approaches to time and good life.

Download Full-text

Bentonite slurry infiltration into sand: filter cake formation under various conditions

Géotechnique ◽

10.1680/jgeot.18.p.094 ◽

2019 ◽

Vol 69 (12) ◽

pp. 1095-1106 ◽

Cited By ~ 5

Author(s):

Tao Xu ◽

Adam Bezuijen

Keyword(s):

Filter Cake ◽

Sand Filter ◽

Bentonite Slurry ◽

Cake Formation

Download Full-text

The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

Scientific Reports ◽

10.1038/s41598-021-85712-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Charalampos Konstantinou ◽

Yuze Wang ◽

Giovanna Biscontin ◽

Kenichi Soga

Keyword(s):

Calcium Carbonate ◽

Calcium Chloride ◽

Urease Activity ◽

Coarse Sand ◽

Carbonate Precipitation ◽

Population Densities ◽

Carbonate Cements ◽

Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

Download Full-text

Intracellular pH modulates the availability of vascular L-type Ca2+ channels.

The Journal of General Physiology ◽

10.1085/jgp.103.4.647 ◽

1994 ◽

Vol 103 (4) ◽

pp. 647-663 ◽

Cited By ~ 67

Author(s):

U Klöckner ◽

G Isenberg

Keyword(s):

Intracellular Ph ◽

Single Channel ◽

Surface Membrane ◽

Life Time ◽

Bicarbonate Buffer ◽

State Changes ◽

Channel Currents ◽

Inside Out ◽

Ca2 Channels

L-type Ca2+ channel currents were recorded from myocytes isolated from bovine pial and porcine coronary arteries to study the influence of changes in intracellular pH (pHi). Whole cell ICa fell when pHi was made more acidic by substituting HEPES/NaOH with CO2/bicarbonate buffer (pHo 7.4, 36 degrees C), and increased when pHi was made more alkaline by addition of 20 mM NH4Cl. Peak ICa was less pHi sensitive than late ICa (170 ms after depolarization to 0 mV). pHi-effects on single Ca2+ channel currents were studied with 110 mM BaCl2 as the charge carrier (22 degrees C, pHo 7.4). In cell-attached patches pHi was changed by extracellular NH4Cl or through the opened cell. In inside-out patches pHi was controlled through the bath. Independent of the method used the following results were obtained: (a) Single channel conductance (24 pS) and life time of the open state were not influenced by pHi (between pHi 6 and 8.4). (b) Alkaline pHi increased and acidic pHi reduced the channel availability (frequency of nonblank sweeps). (c) Alkaline pHi increased and acidic pHi reduced the frequency of late channel re-openings. The effects are discussed in terms of a deprotonation (protonation) of cytosolic binding sites that favor (prevent) the shift of the channels from a sleepy to an available state. Changes of bath pHo mimicked the pHi effects within 20 s, suggesting that protons can rapidly permeate through the surface membrane of vascular smooth muscle cells. The role of pHi in Ca2+ homeostases and vasotonus is discussed.

Download Full-text