Centre De Recherches Metallurgiques-centrum Voor Research in De

Siderurgiemaritime-maritime Staalnijverheid

Christian Rubens Josis

Andre Hans

Theophile Martens

A method of purifying waste water, for example waste water from a coking plant, comprises supplying waste water to be purified to the upper part of a stripping column comprising a plurality of substantially horizontal plates disposed above one another, supplying vapor to the lower part of the column, and supplying a strong base to the column laterally at one or more levels, wherein the water to be stripped is passed downwardly from the top of the column across a number of successive plates sufficient to permit the pH of the water to decrease to a value below 7, and wherein the base is supplied at a level or levels lower than that at which the pH has decreased to the above value.

Method of purifying waste water

Waste water from coke ovens is purified by passing the waste water and a stripping fluid through a stripping column in counterflow. Non-volatile ammonium compounds are removed in one region of the column, phenolic compounds are removed in another region, and volatile ammonium compounds are removed in yet another region. The region in which phenolic compounds are removed is disposed at such a location that no ammoniacal vapor can traverse it. An acid and a strong base are fed laterally into the column at two different levels.

Waste water purification processes

Liquid and gaseous phases are contacted in a column having a plurality of perforated plates spaced one above another. Each plate undergoes rotational or translational movement while at least one of its faces is subjected to a cleaning operation.

Method of contacting liquid and gaseous phases

Volatile compounds are desorbed from an aqueous liquid containing ammonia, by means of a stripping column. The aqueous liquid is supplied to the upper part of the column and a gaseous mixture including free oxygen is blown into the lower part of the column. Sodium hydroxide and/or calcium hydroxide is supplied to an intermediate part of the column at a plurality of levels. A gaseous mixture including ammonia is withdrawn from the top of the column. The pH and the temperature of the aqueous liquid are measured at a plurality of levels in the column. The flow rate of the aqueous liquid and the flow rate and temperature of the gaseous mixture blown in and of the hydroxide are controlled so that the pH of the aqueous liquid, at least in a predetermined zone of the column, is at least 11.

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Gembloux, Belgium

Christian Rubens Josis