Abstract: An apparatus for selectively aerating or anaerobically mixing a liquid in a container includes a hollow, star-shaped, multi-vaned rotor (6) arranged in the bottom region of the container (1) for rotation about a vertical axis. The hollow interior of the rotor at one of the two opposite faces thereof is in communication with a gas feed line (15), and each of the vanes (10) at its trailing flank (11), as viewed in the direction of rotation of the rotor, is provided with a respective gas exit opening (12). The inter-vane spaces of the rotor are open at one of its two opposite faces for admitting liquid from the container into those spaces. The rotor is surrounded by a stator (7) providing a plurality of circumferentially spaced flow channels (9) for receiving and guiding away either liquid with admixed gas when gas flows through the gas feed line or liquid without admixed gas when no gas flows through the gas feed line.

Abstract: An apparatus for aerating liquids includes a gas- and liquid-feeding rotor (6) and a surrounding stator (7) arranged in the bottom region of a container (2). The rotor (6) is mounted for rotation about a vertical axis, and the stator (7) comprises two vertically spaced, horizontally parallel, annular plates (8, 8a) defining a central rotor-accommodating cavity (7b) and includes a plurality of circumferentially spaced guide channels (9) located between the plates and arranged non-radially in the direction of rotation of the rotor (6) for conducting the gas-liquid mixture from the stator cavity (7b) to the outer perimeter of the stator (7).

Abstract: A process and system for enhancing the oxygen uptake by a liquid being aerated in a basin or tank with the aid of an aerator which can only aerate the liquid over a cross-sectional zone smaller than the total floor surface of the basin or tank. To achieve the enhancement, there is provided vertically above the aerator but at the surface of the body of liquid an enclosure which is open at its top and bottom and has a cross-sectional size sufficient to surround approximately the entire region where the rising directly aerated quantity of liquid reaches the surface of the body liquid.

Abstract: In an ultrafiltration of a liquid having a starting solids concentration, in which the liquid is pumped through a filtration circuit including at least one membrane filter, and the loss of liquid resulting from the continuous extraction of filtrate from the filtration circuit is compensated for by feeding unfiltered liquid into the filtration circuit from a separate concentrate container which is connected with the filtration circuit by a feedline and a return line for flow of liquid to and from the filtration circuit, the liquid in the filtration circuit is periodically and repeatedly supplemented by additions of fresh unfiltered liquid taken from a reservoir having the starting solids concentration so as to repeatedly bring the solids concentration in the filtration circuit closer to the starting concentration.

Abstract: A process for the production of vinegar with an acetic acid concentration of more than 12 grams per 100 milliliters of vinegar, by means of a single-stage submerged fermentation of alcohol-containing mashes in a series of successive fermentation periods. In each such period, a quantity of finished vinegar constituting between about 20% and less than 40% of the contents of the fermentation tank and having the requisite acetic acid concentration is extracted from the fermentation tank and replaced by a like quantity of fresh mash having an acetic acid concentration of up to 2 g/100 ml and an alcohol concentration of more than 10 volume percent, in such a manner that the starting concentrations in the tank for each of the successive fermentation periods are more than 9 g/100 ml but less than 13 g/100 ml acetic acid and correspondingly less than 4 vol. % but more than 2.5 vol. % alcohol. In a refinement of the process, a maximum hourly increase in acidity of between about 0.17 g/100 ml and about 0.

Abstract: The present invention relates to a process and an apparatus for dispersing a gas in a liquid flowing within a vertical cycle through two reaction zones arranged in parallel within a reactor, the liquid/gas mixture flowing upwards in the first reaction zone due to the air-lift pump effect and being degassified at the transition from the first reaction zone to the second reaction zone and the completely or partly degassified liquid flowing down and the liquid being remixed with gas (preferably air) at the transition from the second to the first reaction zone below the two reaction zones.

Abstract: In the ultrafiltration of liquids such as vinegar, wine, etc., the liquid to be filtered is fed from and back to a circulating tank through at least one filtration circuit including at least two serially connected, vertically spaced, non-horizontal filter modules through each of which the liquid flows from top to bottom. Each filter module consists of a pipe enclosing a bundle of capillary tubes of semi-permeable membrane material and having a lateral outlet for filtered liquid. Each two successive filter modules are separated from one another by a fall interval zone through which unfiltered liquid can flow with a negligibly low pressure drop from the outlet of the upper filter module to the inlet of the lower one, and each fall interval zone is so arranged that the pressure drop occurring in the upper one of each two successive filter modules is equalized, to the extent of about 0.5 to 1.

Abstract: A novel two-stage submerged fermentation process for producing vinegar with an acetic acid concentration of more than 15% is disclosed. In the first fermentation stage, the total concentration (i.e. the sum of the alcohol and acetic acid concentrations) increases from a starting level between 12 and 15% to a level above 15%, generally between 15 and 17%, but the acetic acid concentration is not permitted to exceed 15% while the alcohol concentration is maintained between about 1 to 5%, whereby both bacteria multiplication and acidification take place in the fermenting liquid. In the second fermentation stage, the total concentration is maintained constant but the acetic acid concentration is permitted to rise above 15% while the alcohol concentration drops almost to zero, whereby mainly acidification will occur while bacteria multiplication decreases and stops. The second stage is terminated when the desired acetic acid concentration above 15% is reached.

Abstract: Liquids containing microorganisms, macromolecules or finely-divided solid matter in a liquid are filtration-concentrated by movement of the liquid containing such particles through an elongated tubular channel having membrane filters, as walls thereof, with flat surfaces and pore diameters between 10.sup..sup.-2 mm and 10.sup..sup.-4 mm, preferably 2.times.10.sup..sup.-4 to 3.times.10.sup..sup.-4 mm. Laminar flow is maintained at the filter surface and forced transverse movement of contained particles into the filter is provided through a moderate static pressure head. The particle movement is in some embodiments supplemented by heavier particles used to transfer momentum to particles to be filtered thereby. Clogging of the filters is thereby reduced with resultant longer service life and longer intervals between filter maintenance or replacement.