Sterilization of Air by Heat

Elsworth, R.; Telling, R. C.; Ford, J. W. S.

doi:10.1017/s0022172400000954

Cited by 13 publications

(3 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, even if no contaminants are found in a sample of 1000 colonies examined, there is still a 5 yo chance that the degree of contamination is really as high as 0.3y0. The same considerations apply in any form of sterility testing and are discussed in more detail by Elsworth, Telling & Ford (1955).…”

Section: Maintenance Of P U R I T Y Of Culturementioning

confidence: 99%

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

Herbert¹,

Elsworth²,

Telling³

1956

Journal of General Microbiology

Self Cite

978

416

View full text Add to dashboard Cite

SUMMARY: A theoretical treatment of continuous culture is given, which allows quantitative prediction of the steady-state concentrations of bacteria and substrate in the culture, and how these may be expected to vary with change of medium, concentration and flow-rate. The layout and operation of a small pilot plant for the continuous culture of bacteria are described. This plant has been operated continuously for periods of up to 4 months without breakdown or contamination of the culture. No alterations in the properties of the organisms studied have occurred during such periods of continuous culture. Results are given of a series of experiments on the continuous culture of Aerobacter cloacae in a chemically defined medium, designed to allow quantitative comparison with the results predicted by the theory. The relative advantages of batch and continuous culture as production processes are discussed, and it is concluded that continuous culture may usually be expected to show a five to tenfold increase in output as compared with a batch process.The continuous culture of micro-organisms is a technique of increasing importance in microbiology. The essential feature of this technique is that microbial growth in a continuous culture takes place under steady-state conditions; that is, growth occurs a t a constant rate and in a constant environment. Such factors as pH value, concentrations of nutrients, metabolic products and oxygen, which inevitably change during the ' growth cycle ' of a batch culture, are all maintained constant in a continuous culture; moreover, they may be independently controlled by the experimenter. These features of the continuous culture technique make it a valuable research tool, while it offers many advantages, in the form of more economical production techniques, to the industrial microbiologist. Nevertheless, the technique has so far been comparatively little used. (The review of Novick (1955) lists nearly all the work on the subject that has yet appeared.) The reasons for this relative neglect are, we believe, twofold.The first reason is the lack of a generally accepted theoretical background. Continuous culture presents theoretical problems of an essentially kinetic nature which must be solved before the technique can be intelligently applied.

show abstract

Section: Maintenance Of P U R I T Y Of Culturementioning

confidence: 99%

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

Herbert¹,

Elsworth²,

Telling³

1956

Journal of General Microbiology

Self Cite

978

416

View full text Add to dashboard Cite

show abstract

“…Continuous thermal sterilization of air is a simple concept that was first introduced in 1950–1960, when the needs for supplying sterile air to biological reactors appeared (Humphrey 1960 ). Elsworth et al ( 1955 ) reported that an air sterilizer operated at 300 °C and a minimum residence time of 1.6 s could reduce the penetration of spores suspended in air to 1 in 470 million. The basic idea of thermal sterilization is to heat the air stream to a sufficiently high temperature (sterilization temperature), and to keep it at that temperature for some time (sterilization time) in order to effectively inactivate the microorganism.…”

Section: Introductionmentioning

confidence: 99%

Simulation of thermal sanitization of air with heat recovery as applied to airborne pathogen deactivation

Busto

Tarifa

Cristaldi

et al. 2022

Int. J. Environ. Sci. Technol.

View full text Add to dashboard Cite

The technique of air sterilization by thermal effect was revisited in this work. The impact of incorporating a high efficiency heat recovery exchanger to a sterilizing cell was especially assessed. A mathematical model was developed to study the dynamics and the steady state of the sterilizer. Computer simulation and reported data of thermal inactivation of pathogens permitted obtaining results for a proof-of-concept. The simulation results confirmed that the incorporation of a heat recovery exchanger permits saving more than 90% of the energy needed to heat the air to the temperature necessary for sterilization, i.e., sterilization without heat recovery consumes 10–20 times the energy of the same sterilization device with heat recovery. Sanitization temperature is the main process variable for sanitization, a fact related to the activated nature of the thermal inactivation of viruses and bacteria. Heat recovery efficiency was a strong function of the heat transfer parameters but also rather insensitive to the cell temperature. The heat transfer area determined the maximum capacity of the sterilizer (maximum air flowrate) given the restrictions of minimum sanitization efficiency and maximum power consumption. The proposed thermal sterilization device has important advantages of robustness and simplicity over other commercial sterilization devices, needing practically no maintenance and eliminating a big variety of microorganisms to any desired degree. For most pathogens, the inactivation can be total. This result is not affected by the uncertainties in thermal inactivation data, due to the Arrhenius-like dependence of inactivation. Temperature can be adjusted to achieve any removal degree.

show abstract

“…Thermal sterilization is a simple concept that was first introduced in 1950-1960 to satisfy the supply of sterile air to biological reactors. Elsworth et al [16] early reported that heating air at 300˚C for a minimum residence time of 1.6 s could reduce the penetration of spores in the air to 1 in 470 million. Thermal treatment is a robust and proven technique for the destruction of microorganisms in the air, both pathogenic and non-pathogenic.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Virus Sanitization Alternatives and Optimization of a Thermal Air Purifier for SARS-CoV-2

Tarifa¹,

Dosso²,

Vera³

2022

OJAppS

View full text Add to dashboard Cite

Air sanitization acquired renewed interest during the COVID-19 outbreak, especially in hospital rooms and intensive care units. In this work, mathematical analysis was done of the convenience of sanitizing the air of whole rooms or personalized isolation tents. Centralized air sanitization was found to have low effectiveness due to three reasons: 1) the constant virus emission from patients; 2) the practical upper limits of air recycle flowrates; 3) the low value of the minimum infective dose of SARS-CoV-2. Personalized air sanitization was the best option. Virus inactivation by thermal effect was then revisited, and a steady-state model was formulated for an efficient and personalized thermal sterilizer. An analytical solution was obtained for temperature and virus concentration in different parts of the sterilizer. Cell temperature was found to be the main variable for sterilization due to the Arrhenius-like form of the kinetic constant of virus deactivation. An objective cost function was written and subjected to conditions of minimum patient ventilation rate and minimum virus removal effectiveness. Numerical optimization gave an optimal design with the intrinsic advantages of thermal sanitization, i.e., simplicity, robustness, minimum maintenance and high sanitization rate.

show abstract

Sterilization of Air by Heat

Abstract: SummaryEquipment for the sterilization of air by heat with capacities of 140 l./min., and 1700 l./min. respectively is described. An improved method for testing sterility is given.

Cited by 13 publications

References 5 publications

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

The Continuous Culture of Bacteria; a Theoretical and Experimental Study

Simulation of thermal sanitization of air with heat recovery as applied to airborne pathogen deactivation

Analysis of Virus Sanitization Alternatives and Optimization of a Thermal Air Purifier for SARS-CoV-2

Contact Info

Product

Resources

About