Use of modified diatomaceous earth for removal and recovery of viruses in water

Farrah, Samuel R.; Preston, David R.; Toranzos, Gary A.; Girard, Michel; Erdos, Greg; Vasuhdivan, V

doi:10.1128/aem.57.9.2502-2506.1991

Cited by 42 publications

(12 citation statements)

References 21 publications

(33 reference statements)

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“…Common filter aids are siliceous materials such as diatomaceous earth (DE), fossilized diatoms that have naturally occurring pore structures, and perlite, a glassy volcanic rock. These filter aids have utility in water filtration applications (Farrah et al, 1991;Kalyani, Priya, & Rao, 2005). The final component of a depth filter is a polymeric binder, typically with some level of cationic charge resulting from primary to quaternary amine functional groups (3M, 2013).…”

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confidence: 99%

Contributions of depth filter components to protein adsorption in bioprocessing

Khanal

Singh

Traylor

et al. 2018

Biotech & Bioengineering

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Depth filtration is widely used in downstream bioprocessing to remove particulate contaminants via depth straining and is therefore applied to harvest clarification and other processing steps. However, depth filtration also removes proteins via adsorption, which can contribute variously to impurity clearance and to reduction in product yield. The adsorption may occur on the different components of the depth filter, that is, filter aid, binder, and cellulose filter. We measured adsorption of several model proteins and therapeutic proteins onto filter aids, cellulose, and commercial depth filters at pH 5-8 and ionic strengths <50 mM and correlated the adsorption data to bulk measured properties such as surface area, morphology, surface charge density, and composition. We also explored the role of each depth filter component in the adsorption of proteins with different net charges, using confocal microscopy. Our findings show that a complete depth filter's maximum adsorptive capacity for proteins can be estimated by its protein monolayer coverage values, which are of order mg/m , depending on the protein size. Furthermore, the extent of adsorption of different proteins appears to depend on the nature of the resin binder and its extent of coating over the depth filter surface, particularly in masking the cation-exchanger-like capacity of the siliceous filter aids. In addition to guiding improved depth filter selection, the findings can be leveraged in inspiring a more intentional selection of components and design of depth filter construction for particular impurity removal targets.

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Contributions of depth filter components to protein adsorption in bioprocessing

Khanal

Singh

Traylor

et al. 2018

Biotech & Bioengineering

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“…These findings are similar to those in the literature which suggest that diatomaceous earth and Fullers earth provide a matrix for virus adsorption. [5][6][7][8] These filtration aids have also been shown to be useful in removing other types of microbial contamination including endotoxin and yeasts. 5,10 Viruses have been shown to interact electrostatically with the filtration aids used in this study, 6,8,14 which can be controlled by maintaining pH, whereas hydrophobic interactions can be di#icult to control.…”

Section: Discussionmentioning

confidence: 99%

“…The filtration aids, Hyflo Super-Cel and Fulmont Super A, are used commonly in wine making to reduce turbidity, 1,2 in food technology applications 3,4 and in the water purification setting. [5][6][7][8][9] The capability of filtering aids to lower the levels of yeast and bacteria in wine preparations has been described, 10 as has their ability to remove viruses and endotoxins from water. [5][6][7][8][9] However, their utility as virus removal agents in a biopharmaceutical setting is not described in the literature.…”

Section: Introductionmentioning

confidence: 99%

The Removal of Viruses During the Purification of Equine Antisera using Filtration Aids Hyflo Super-Cel™ and Fulmont™ Super A

Cameron-Smith¹,

Miloradovic²,

Cheyne³

et al. 2000

Biologicals

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“…Cryptosporidium oocysts carry a negative surface electrical charge in the pH range of natural water sources, 7 – 9 as do natural filter media such as sand and diatomaceous earth 10 , 11 . Thus, removal of the oocyst particles by filtration (without chemical conditioning) is difficult because of electrostatic repulsion between the oocysts and the filter media surface.…”

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confidence: 99%

“…Thus, removal of the oocyst particles by filtration (without chemical conditioning) is difficult because of electrostatic repulsion between the oocysts and the filter media surface. Coatings of metallic hydroxides, oxides, and peroxides on filter media improved the removal of bacteria and viruses from, and reduced turbidity in, water and wastewater 11 – 15 . However, no studies have determined whether the application of electropositive coatings to granular filtration media improves removal of Cryptosporidium .…”

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confidence: 99%

Improving Filtration of Cryptosporidium

Shaw¹,

Walker²,

Koopman³

2000

Journal AWWA

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ryptosporidium in water supplies is a widespread problem in the United States and elsewhere. This protozoan causes severe gastroenteritis that is potentially fatal to infants and immunocompromised individuals and that does not respond well to available therapies. Cryptosporidium was detectable in 77% of rivers and 75% of lakes sampled in a US survey. 1 Moreover, Cryptosporidium oocysts were detectable in 83% of pristine water sources (no human activity in the watershed) and 28% of treated drinking water samples. In the United States, > 431,000 confirmed cases of cryptosporidiosis have been reported since the disease was identified in 1976. 1 Most (403,000) of these cases were diagnosed during the 1993 outbreak in Milwaukee, Wis. Some 250-500 million infections occur annually in Asia, Africa, and Latin America. 2 The infective stage of the disease is the oocyst, and the infective dosage (generally reported as 10-100 oocysts) may be as low as a single oocyst. 3 The oocysts resist disinfectants and most environmental conditions, thus making their physical removal necessary. Chemical conditioning and optimal operation of filtration systems can remove > 99 percent of oocysts from water. 4,5 Suboptimal flocculation can substantially decrease performance, however, and drop removal to 96% at a superficial velocity of 293 m/d (5.0 gpm/sq ft). 4 Fogel 6 obtained removals of only 2-43% at hydraulic loads of 24-475 m/d (0.4-8.2 gpm/sq ft) when chemical conditioning was not practiced.Cryptosporidium oocysts carry a negative surface electrical charge in the pH range of natural water sources, 7-9 as do natural filter media such as sand and diatoma-C Surface coating of hydrous iron aluminum oxide on Ottawa sand was investigated as a means of improving the removal of Cryptosporidium oocysts from water by filtration. Coating the sand increased the zeta potential from -40 to +45 mV at pH 7.0, increasing the potential for interaction with the negatively charged (-25 mV at pH 7.0) Cryptosporidium oocysts. Water seeded with Cryptosporidium oocysts was passed through parallel columns of uncoated and coated sand at superficial velocities of 200-800 m/d (3.5-14 gpm/sq ft) and column lengths of 100-400 mm (4-16 in.). In every trial, coated sand removed significantly more oocysts than uncoated sand. Filter coefficients of coated sand were 2.9 times as high as those of uncoated sand, indicating that coating can significantly improve the removal of Cryptosporidium by granular media filters.

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Use of modified diatomaceous earth for removal and recovery of viruses in water

Cited by 42 publications

References 21 publications

Contributions of depth filter components to protein adsorption in bioprocessing

Contributions of depth filter components to protein adsorption in bioprocessing

The Removal of Viruses During the Purification of Equine Antisera using Filtration Aids Hyflo Super-Cel™ and Fulmont™ Super A

Improving Filtration of Cryptosporidium

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