|FORMALDEHYDE AND GLUTARALDEHYDE
Formaldehyde has been used for many years for disinfection and fumigation. Many recommendations have been published for routine disinfection and fumigation with formaldehyde, but due to misunderstanding, miscalculation, poor equipment and anxiety of operators caused annoying aroused by irritial effect and reports of it's toxicity, results have been inconsistent.
In Holland, Miltenburg reported in 1981 that infectious stunting was controlled in broiler crops by implementing cleansing programmes in which formaldehyde was used for both surface disinfection and fumigation.
In Belgium, Muelmans and Halen reported that formaldehyde, glutaraldehyde and formula based upon mixtures of two chemicals, were more effective than other formula utilising iodine, chlorine and phenols, against the I.B.D. virus and Avian Reovirus, when exposure occured at low temperatures in the presence of poultry faeces.
Research work in Sweden has shown that formaldehyde and glutaraldehyde kill organisms contaminating surfaces when applied as gas/aerosol mixtures (fog) in confined spaces.
In Germany, the approval scheme for disinfectants for use in livestock situations, conducted by the German Veterinary Association, list many such formula as effective against all of the significant groups of disease organisms.
Thermal Fog Generators
This process utilises the high velocity, hot gas/air jet stream generated by a pulse jet engine. The equipment is designed so that a variety of chemical products can be injected at measured and controlled rates into the jet streams, under pressure, through a venturi system.
Initially, the shearing action of the jet stream breaks up the chemical into an aerosol, which in turn is vapourised by the jet stream temperature. However, the dwelltime of the chemical in the vapour phase is brief, since it travels only 5 - 7 cm before being discharged into the atmosphere, as a dense cloud of fog at a high velocity. This chemical fog quickly fills the enclosed space, enveloping all surfaces and equipment and penetrating the structure, ventilation ducts, voids etc.
The IGEBA TF 75 and TF 95 machines have a capacity to treat enclosed spaces at a rate of up to 150 - 200 m3 / 500 - 7000 m3 per minute, utilising approximately 2-2,5l/100 m of chemical solution, for the purpose of disinfection or disinfestation by fumigation.
In practise it is often possible to locate the fog generator out of doors, with the chemical fog jet stream directed into the building, the operator remaining out of doors safe from any risk of hazard.
The use of IGEBA Fog Generators for the Fumigation of Livestock Houses
The equipment can be used for the application of suitable chemicals for fumigation to achieve disinfection and / or disinfestation of livestock houses, following cleaning to prevent rapid air changes.
The application of chemicals is extremely rapid and results in a uniform dissemination of the chemical fog. In an enclosure of 20.000 m 2 / 2.000 m2, application of chemical is completed within 45 / 50 minutes. E.g.a. 20.000 m2 (2.000 m2) poultry houses enclosing approximately 150.000 m3 (4.500 m3) would require 45 litres of 40 % formaldehyde solution to achieve a level of 4 mgm formaldehyde per litre of enclosed air space. This volume can be applied using the IGEBA TF 95 HD fitted with the No. 3 chemical solution jet in 45 / 50 minutes, i.e. 1 litre per minute.
Works carried out under veterinary supervision in Turkey breeding houses in which a mixture of formaldehyde and glutaraldehyde was applied - the volume of the special chemical formula used totalling 30 litres, requiring an application time of approximately 30 minutes. The process resulted in control of a costly P.M. virus infection which had persisted in breeding flocks for 2 years.
The large volume of chemicals applied as a thermal fog ensures a high humidity which aids surface disinfection and while the germicidal properties of formaldehyde and glutaraldehyde, like any other disinfectant chemical vary with temperature (thermal coefficient Q10 = 2), satisfactory performance has been achieved with an external ambient temperature below 0° C.
This technique for fumigation / disinfection offers major advantages in application, minimizing working hours and labour costs. It is highly efficient in that the chemical application can be supervised and completed in the largest of houses in less than one hour, ensuring exposure of house surfaces and retained equipment to the intended effective level of chemical, without risk of continuous dilution by natural air changes while the fumigation process is being carried out.
The control and reduction of operator hazard makes a significant contribution to the achievment of effective disease control in intensive livestock production.