Liquid waste treatment

“The treatment of liquid hazardous waste with chemical-physical means has the following goals:

  • Reduction of the risk potential
  • Chemical conversion … to be separate ingredients by physical means
  • Separation of material mixtures by means of physical methods,
  • Pre-treatment of waste for the material or thermal recycling,
  • Reduction of the mass of the waste to be landfilled,
  • Creating un-reactive and therefore harmless non-recyclable waste materials,
  • Attainment of combustible waste materials in calorific form,
  • Avoidance of pollutant transfer from waste to other media,
  • greatest possibleoperating and accidentalsafety
cited from: M. Wagner, H. Menapace, R. Frate: state of art at the chemcal,physikal treatment of liquid waste, IAE Leoben, 2010

Drying is basically achieved by the processes vaporizing, evaporation and freezing. Thereby contact convection and radiation drying procedures can be used.

In contact drying, the heat is supplied by fluid contact with the hot walls which are heated by a constant stream of various media, such as saturated steam or thermal oil. According to this principle kneading drier, thin film evaporators, washer dryer and steam fluidized bed dryer work.

At convection drying the heat is transferred to the media by hot gases. The water contained vaporizes and leaves with the hot gas stream that has a high water absorption capacity due to the high temperature.

Among the convection dryers count drum dryers, belt dryers and fluidized bed dryers. The exhaust vapors (water vapor) are condensed and subjected to a subsequent purification.

In the radiation drying, heat in the form of radiation is transferred to the medium.”

cited from: homepage of the research institute for water- and waste management at the RWTH Aachen (FiW) e.V., 2010

Stripping is a physical separation process where one or more components are removed from a liquid stream by a vapour stream. In industrial applications the liquid and vapour streams can have co-current or counter-current flows. Stripping is usually carried out in either a packed or trayed column. Stripping works on the basis of mass transfer. The idea is to make the conditions favourable for the component A in the liquid phase to transfer to the vapour phase. This involves a gas-liquid interface that A must cross.“

cited and translated from: Seite „Strippung“. In: Wikipedia, Die freie Enzyklopädie. Bearbeitungsstand: 11. April 2014, 06:45 UTC. URL: (Abgerufen: 11. September 2014, 16:47 UTC) 

EnviCare® Engineering GmbH has detailed engineering and application knowledge for those above mentioned methods for the purification of liquid wastes.

Realised projects gave us expertise

For example, projects to strip sulfide out of permeate of a reverse osmosis or ammonium from landfill leachate, to clean inorganic liquids through flocculation/ precipitation, to thicken organic sludge by means of thermal drying have been realized. In addition, many applications for the purification of aqueous waste with biological treatment methods have been implemented that have already been described elsewhere.

 => Stripper Erzberg

EnviCare® Engineering GmbH
engineering consultant for process technology

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