Membrane filter techniques

2022 ◽  
pp. 39-42
Author(s):  
Osman Erkmen
Keyword(s):  
Membrane Filter

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

Bacterial die-away rates in red sea waters

1995 ◽  
Vol 32 (2) ◽  
pp. 45-52 ◽  
Author(s):  
H. Z. Sarikaya ◽  
A. M. Saatçi
Keyword(s):  
Solar Radiation ◽  
Decay Rate ◽  
Sea Water ◽  
Membrane Filter ◽  
Linear Regression Analysis ◽  
Total Coliform ◽  
Coliform Bacteria ◽  
Decay Rate Constant ◽  
Solar Intensity ◽  
Log Normal

Total coliform bacteria have been chosen as the indicator organism. Coliform die-away experiments have been carried out in unpolluted sea water samples collected at about 100 m off the coastline and under controlled environmental conditions. The samples were transformed into one litre clean glass beakers which were kept at constant temperature and were exposed to the solar radiation. The membrane filter technique was used for the coliform analysis. The temperature ranged from 20 to 40° C and the dilution ratios ranged from 1/50 to 1/200. Coliform decay rate in the light has been expressed as the summation of the coliform decay rate in the dark and the decay rate due to solar radiation. The solar radiation required for 90 percent coliform removal has been found to range from 17 cal/cm2 to 40 cal/cm2 within the temperature range of 25 to 30° C. Applying the linear regression analysis two different equations have been given for the high (I>10 cal/cm2.hour) and low solar intensity ranges in order to determine the coliform decay rate constant as a function of the solar intensity. T-90 values in the light have been found to follow log-normal distribution with a median T-90 value of 32 minutes. The corresponding T-90 values in the dark were found to be 70-80 times longer. Coliform decay rate in the dark has been correlated with the temperature.

Activated carbon as a better habitat for water and wastewater treatment microorganisms

2000 ◽  
Vol 42 (12) ◽  
pp. 149-154 ◽  
Author(s):  
M. Okada ◽  
H. Morinaga ◽  
W. Nishijima
Keyword(s):  
Batch Culture ◽  
Bacterial Growth ◽  
Membrane Filter ◽  
Synthetic Medium ◽  
Dialysis Tubing ◽  
Water And Wastewater Treatment ◽  
Batch Cultures ◽  
K 12 ◽  
Bacterial Yield ◽  
Adsorption Desorption

Effects of PAC on bacterial activity were evaluated by sequencing batch cultures (20 hours each) of E.coli K-12 on synthetic medium containing glucose as a sole carbon source. Four suspended sequencing batch culture systems were operated; CP: cultures supplemented with PAC, CR: cultures with removal of metabolites by PAC at the end of each batch culture, CD: cultures supplemented with PAC in dialysis tubing to separate from E.coli, and CC: cultures without PAC (control). The supernatant of each batch culture was filtered through a membrane filter (0.2 μm) and was mixed with the same volume of fresh medium to be used as the medium for the next batch culture. The sequencing batch cultures were repeated three times for all the systems. The bacterial growth in CC was inhibited with the increase in the number of batch cultures. Although a significant amount of metabolites was accumulated in the 3rd batch culture of CC, little accumulation was noted in the 3rd batch culture of CP. No growth inhibition was noted in CP for all the batch cultures. The little differences in the bacterial yield and metabolite accumulation between CR and CD suggested that adsorption/desorption of metabolites with PAC did not play a major role in bacterial growth. PAC addition may partly stimulate the growth by the removal of growth inhibiting metabolites. However, the fact that CP showed higher yield than CR and CD indicated that the contact between bacteria and PAC plays a significant role in the growth of bacteria.

Class I–unrestricted noncytotoxic anti–HTLV-I activity of CD8+ T cells

Blood ◽  
2000 ◽  
Vol 96 (5) ◽  
pp. 1994-1995 ◽  
Author(s):  
Masako Moriuchi ◽  
Hiroyuki Moriuchi
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Membrane Filter ◽  
Cd8 T Cell ◽  
Class I ◽  
Type I ◽  
Peripheral Blood Mononuclear ◽  
Permeable Membrane

Abstract Although it is widely believed that viral clearance is mediated principally by the destruction of infected cells by cytotoxic T cells, noncytolytic antiviral activity of CD8+ T cells may play a role in preventing the progression to disease in infections with immunodeficiency viruses and hepatitis B virus. We demonstrate here that (1) replication of human T-lymphotropic virus type I (HTLV-I) is more readily detected from CD8+ T-cell–depleted (CD8−) peripheral blood mononuclear cells (PBMCs) of healthy HTLV-I carriers than from unfractionated PBMCs, (2) cocultures of CD8− PBMCs with autologous or allogeneic CD8+ T cells suppressed HTLV-I replication, and (3) CD8+ T-cell anti-HTLV-I activity is not abrogated intrans-well cultures in which CD8+ cells are separated from CD8− PBMCs by a permeable membrane filter. These results suggest that class I-unrestricted noncytolytic anti–HTLV-I activity is mediated, at least in part by a soluble factor(s), and may play a role in the pathogenesis of HTLV-I infection.

scholarly journals Validation of chemotherapy drug vapor containment of an air cleaning closed-system drug transfer device

2021 ◽  
pp. 107815522110306
Author(s):  
Galit Levin ◽  
Paul JM Sessink
Keyword(s):  
Activated Carbon ◽  
Closed System ◽  
Membrane Filter ◽  
Drug Transfer ◽  
Glass Vessel ◽  
Air Cleaning ◽  
No Release ◽  
Activated Carbon Filter ◽  
Carbon Filter ◽  
Transfer Device

Purpose The purpose of this study was to test the efficacy of ChemfortTM, an air filtration closed-system drug transfer device to prevent release of chemotherapy drug vapors and aerosols under extreme conditions. The air cleaning system is based on the adsorption of drug vapors by an activated carbon filter in the Vial Adaptor before the air is released out of the drug vial. The functionality of the carbon filter was also tested at the end of device’s shelf life, and after a contact period with drug vapors for 7 days. Cyclophosphamide and 5-fluorouracil were the chemotherapy drugs tested. Methods The Vial Adaptor was attached to a drug vial and both were placed in a glass vessel. A needle was punctured through the vessel stopper and the Vial Adaptor septum to allow nitrogen gas to flow into the vial and to exit the vial via the air filter into the glass vessel which was connected to a cold trap. Potential contaminated surfaces in the trap system were wiped or rinsed to collect the escaped drug. Samples were analyzed using liquid chromatography tandem mass spectrometry. Results Cyclophosphamide and 5-fluorouracil were detected on most surfaces inside the trap system for all Vial Adaptors without an activated carbon filter. Contamination did not differ between the Vial Adaptors with and without membrane filter indicating no effect of the membrane filter. The results show no release of either drug for the Vial Adaptors with an activated carbon filter even after 3 years of simulated aging and 7 days of exposure to drug vapors. Conclusions Validation of air cleaning CSTDs is important to secure vapor and aerosol containment of chemotherapy and other hazardous drugs. The presented test method has proven to be appropriate for the validation of ChemfortTM Vial Adaptors. No release of cyclophosphamide and 5- fluorouracil was found even for Vial Adaptors after 3 years of simulated aging and 7 days of exposure to drug vapors.

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