Abstract: In a method of cleaning filter elements a removal of filter cakes formed on the filter cloth of the filter elements is accomplished by the application pressure and vacuum in the alternating fashion to the filter elements after the filtration process has been completed. The cleaning effect is improved due to the pressure fluctuations because the filter cloth expands upon those fluctuations and filter cake formed thereon is peeled off that filter cloth.

Abstract: A filtering apparatus comprises a housing defining a generally closed chamber in which is provided a hollow rotatable shaft that carries a plurality of filter elements. Each of these elements is formed as an upwardly dished fluid-impervious metal plate formed with a central hole through which the hollow shaft passes and having a concave upper face formed with an array of spaced-apart bosses. A fluid-pervious filter cloth lies on the plate directly against the bosses so as to be spaced from the plate between the bosses. A ring secured to the smooth edge of each plate secures the respective filter cloth in place.

Abstract: From a vessel in which micro-organisms grow in a liquid medium containing gas bubbles, a sample is withdrawn into an exterior measuring chamber by means of suction. Gas bubbles are allowed to escape from the sample and thereafter the opacity or turbidity of the sample is measured by passing a light beam through it.