Abstract: Process for separation and purifying pigment suspensions and suspensions of pigment intermediates in a liquid by means of a membrane separation process, whereby the suspension to be treated is uniformly fed to and circulated through a microfiltration unit containing at least one semi-permeable membrane and the separated liquid flows off through the membrane as permeate which process comprises replacing the permeate gradually by a washing liquid that differs from the first liquid such that the total amount of washing liquid fed into the system is 1 to 15 times the total volume of the initial suspension, and separating the resultant suspension from the liquid by means of conventional filtration or drying apparatus. The process is particularly suitable for processing fine pigment suspensions often obtained in pigment synthesis.

Abstract: A process is described for converting sparingly soluble salts of anionic dyes and fluorescent brighteners into more soluble salts by means of cation exchange without intermediate isolation of the free dye acid, which comprises carrying out the cation exchange by using Donnan dialysis.The concentrated dye and brightener solutions obtained in this way are stable and can be directly used for dyeing or printing textile material.

Abstract: Process for the continuous separation of oil-in-water emulsions, which may contain surfactants, for example oil- and surfactant-containing effluents, by electrolysis, which comprises electrolysing such emulsions at a pH value of 5 to 10 and under a potential difference of at least 1.5 volts between the electrodes, optionally in the presence of a coagulating agent, with the formation of discrete oil particles, floating these oil particles with the aid of hydrogen gas formed simultaneously at the cathode, and then separating off the oily phase thus formed which is optionally condensed by the addition of flocculating agents.

Abstract: A process for purifying effluents which contain proteins, which process comprises treating said effluents with a basic polymer compound and separating the flocks that are formed from the effluent.

Abstract: A device for sampling fluid is provided which comprises a plurality of sample vessels uniformly spaced apart in a circle and means for the alternate feeding of fluid into the individual sample vessels. A buffer vessel whose volume is at least three to five times greater than that of each individual sample vessel is connected upstream in series to the sample vessels. The sample vessels are U-shaped and have two substantially upright tubular arms which are joined together at their bottom ends. One arm is smaller in diameter and ends below the opening of the other arm or has a mouth or opening below the opening of the other arm. The means for feeding the fluid enter the thicker and higher arm of the sample vessels and are so built as to be able to empty the entire contents of the buffer vessel in the course of at most one to two minutes into the sample vessel.