Destruction of microorganisms in gaseous, liq. or pasty medium

摘要

Microorganisms are destroyed in a gaseous, liq. and/or pasty medium by treating the medium with ultrasound. Pref. treatment is for not above 60 secs., at a frequency of not less than 18 kHz (not less than 20 kHz), a capacity of not less than 2000 watts, and a constant or variable temp. of 0-100 deg.C., opt. using an agitated medium. Treatment may be first at a raised temp. and then at a reduced temp., or vice versa, e.g. it may be raised from a starting temp. of not below 58 deg.C. or lowered from a starting temp. of not above 15 deg.C. and may be altered stepwise. Ultrasound treatment may be repeated, and before repitition the temp. of the medium is brought to the initial value. The viscosity of the medium may be reduced. The pH is not 7, pref. below 6.8 or above 7.1. Before, during or after the ultrasound treatment, the medium may be irradiated with micro-waves. The ultrasound intensity may be varied, and is pref. raised during treatment. The intensity is varied in pulses and/or is briefly interrupted, and is pref. accompanised by micro-wave treatment for not above 3 secs.. Several ultrasound sources may be used, in sequence and/or in parallel, with differing capacities, and vertical and/or transverse and/or sloping w.r.t. the medium. The intensity of treatment is controlled by the distance of the ultrasound source from the medium, by contact of the source with medium and/or by the depth of dipping of the source into the medium. In flowing gaseous media, the amt. of dry matter and/or moisture is varied. The temp., pH value, viscosity, dry matter content, moisture content, flow rate and/or degree of agitation of the medium may be varied during, before or after the ultrasound treatment. Coarse and/or fine dispersed substances may be fed into the ultrasound treatment space and/or form additionally in the substrate to be treated, thus accelerating the destruction of microoganisms present and/or the homogenisation. The density of the medium is at least 1.01 g/cc, and its acitivity or water activity is not above 0.995.